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lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> When there are not enough monitors, MPAM is able to emulate ABMC by making a smaller number of monitors assignable. These monitors still need to be allocated from the driver, and mapped to whichever control/monitor group resctrl wants to use them with. Add a second array to hold the monitor values indexed by resctrl's cntr_id. When CDP is in use, two monitors are needed so the available number of counters halves. Platforms with one monitor will have zero monitors when CDP is in use. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since rfc: Move __free kmalloc -> kcalloc Changes since v2: kcalloc -> kmalloc_array sizeof(rmid_array) Return error from resctrl_arch_mbm_cntr_assign_set() --- drivers/resctrl/mpam_internal.h \| 7 +++ drivers/resctrl/mpam_resctrl.c \| 97 +++++++++++++++++++++++++++++++++ 2 files changed, 104 insertions(+) diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index 89f9d374ded0..58076abd5de3 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -367,6 +367,13 @@ struct mpam_resctrl_mon { un-assigned (closid, rmid) are -1. / int mbwu_idx_to_mon; + + /* + * Array of assigned MBWU monitors, indexed by idx argument. + * When ABMC is not in use, this array can be NULL. Otherwise + * it maps idx to the allocated monitor. + / + int assigned_counters; }; static inline int mpam_alloc_csu_mon(struct mpam_class class) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index 3af12ad77fba..2a9efc6c6fae 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -68,6 +68,12 @@ static bool cdp_enabled; static bool cacheinfo_ready; static DECLARE_WAIT_QUEUE_HEAD(wait_cacheinfo_ready); +/ + * L3 local/total may come from different classes - what is the number of MBWU + * 'on L3'? + / +static unsigned int l3_num_allocated_mbwu = ~0; + / Whether this num_mbw_mon could result in a free_running system / static int __mpam_monitors_free_running(u16 num_mbwu_mon) { @@ -76,6 +82,15 @@ static int __mpam_monitors_free_running(u16 num_mbwu_mon) return 0; } +/ + * If l3_num_allocated_mbwu is forced below PARTID * PMG, then the counters + * are not free running, and ABMC's user-interface must be used to assign them. + / +static bool mpam_resctrl_abmc_enabled(void) +{ + return l3_num_allocated_mbwu < resctrl_arch_system_num_rmid_idx(); +} + bool resctrl_arch_alloc_capable(void) { return exposed_alloc_capable; @@ -120,9 +135,26 @@ static void resctrl_reset_task_closids(void) read_unlock(&tasklist_lock); } +static void mpam_resctrl_monitor_sync_abmc_vals(struct rdt_resource l3) +{ + l3->mon.num_mbm_cntrs = l3_num_allocated_mbwu; + if (cdp_enabled) + l3->mon.num_mbm_cntrs /= 2; + + if (l3->mon.num_mbm_cntrs) { + l3->mon.mbm_cntr_assignable = mpam_resctrl_abmc_enabled(); + l3->mon.mbm_assign_on_mkdir = mpam_resctrl_abmc_enabled(); + } else { + l3->mon.mbm_cntr_assignable = false; + l3->mon.mbm_assign_on_mkdir = false; + } +} + int resctrl_arch_set_cdp_enabled(enum resctrl_res_level ignored, bool enable) { u32 partid_i = RESCTRL_RESERVED_CLOSID, partid_d = RESCTRL_RESERVED_CLOSID; + struct mpam_resctrl_res res = &mpam_resctrl_controls[RDT_RESOURCE_L3]; + struct rdt_resource l3 = &res->resctrl_res; cdp_enabled = enable; @@ -138,6 +170,7 @@ int resctrl_arch_set_cdp_enabled(enum resctrl_res_level ignored, bool enable) WRITE_ONCE(arm64_mpam_global_default, mpam_get_regval(current)); resctrl_reset_task_closids(); + mpam_resctrl_monitor_sync_abmc_vals(l3); return 0; } @@ -321,6 +354,11 @@ static bool class_has_usable_mbwu(struct mpam_class class) return true; } + if (cprops->num_mbwu_mon) { + pr_debug("monitors usable via ABMC assignment\n"); + return true; + } + return false; } @@ -597,6 +635,8 @@ static int __alloc_mbwu_mon(struct mpam_class class, int array, array[i] = mbwu_mon; } + l3_num_allocated_mbwu = min(l3_num_allocated_mbwu, num_mbwu_mon); + return 0; } @@ -736,6 +776,19 @@ static void mpam_resctrl_pick_counters(void) mpam_resctrl_counters[QOS_L3_MBM_TOTAL_EVENT_ID].class); } +bool resctrl_arch_mbm_cntr_assign_enabled(struct rdt_resource r) +{ + if (r != &mpam_resctrl_controls[RDT_RESOURCE_L3].resctrl_res) + return false; + + return mpam_resctrl_abmc_enabled(); +} + +int resctrl_arch_mbm_cntr_assign_set(struct rdt_resource r, bool enable) +{ + return -EINVAL; +} + static int mpam_resctrl_control_init(struct mpam_resctrl_res res) { struct mpam_class class = res->class; @@ -811,6 +864,42 @@ static int mpam_resctrl_pick_domain_id(int cpu, struct mpam_component comp) return comp->comp_id; } +/* + * This must run after all event counters have been picked so that any free + * running counters have already been allocated. + / +static int mpam_resctrl_monitor_init_abmc(struct mpam_resctrl_mon mon) +{ + struct mpam_resctrl_res res = &mpam_resctrl_controls[RDT_RESOURCE_L3]; + struct rdt_resource l3 = &res->resctrl_res; + struct mpam_class class = mon->class; + u16 num_mbwu_mon; + + if (mon->mbwu_idx_to_mon) { + pr_debug("monitors free running\n"); + return 0; + } + + int rmid_array __free(kfree) = + kmalloc_array(resctrl_arch_system_num_rmid_idx(), sizeof(rmid_array), GFP_KERNEL); + + if (!rmid_array) { + pr_debug("Failed to allocate RMID array\n"); + return -ENOMEM; + } + memset(rmid_array, -1, resctrl_arch_system_num_rmid_idx() sizeof(int)); + + num_mbwu_mon = class->props.num_mbwu_mon; + mon->assigned_counters = __alloc_mbwu_array(mon->class, num_mbwu_mon); + if (IS_ERR(mon->assigned_counters)) + return PTR_ERR(mon->assigned_counters); + mon->mbwu_idx_to_mon = no_free_ptr(rmid_array); + + mpam_resctrl_monitor_sync_abmc_vals(l3); + + return 0; +} + static int mpam_resctrl_monitor_init(struct mpam_resctrl_mon mon, enum resctrl_event_id type) { @@ -857,6 +946,14 @@ static int mpam_resctrl_monitor_init(struct mpam_resctrl_mon mon, * group can be allocated freely: */ l3->mon.num_rmid = mpam_pmg_max + 1; + + switch (type) { + case QOS_L3_MBM_LOCAL_EVENT_ID: + case QOS_L3_MBM_TOTAL_EVENT_ID: + return mpam_resctrl_monitor_init_abmc(mon); + default: + return 0; + } } return 0; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:58:58 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> ABMC exposes a fun corner case where a platform with one monitor can use ABMC for assignable counters - but not when CDP is enabled. Add some tests. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- drivers/resctrl/test_mpam_resctrl.c \| 62 +++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) diff --git a/drivers/resctrl/test_mpam_resctrl.c b/drivers/resctrl/test_mpam_resctrl.c index a20da161d965..fd63f7bbb147 100644 --- a/drivers/resctrl/test_mpam_resctrl.c +++ b/drivers/resctrl/test_mpam_resctrl.c @@ -344,6 +344,67 @@ static void test_rmid_idx_encoding(struct kunit test) mpam_pmg_max = orig_mpam_pmg_max; } +static void test_num_assignable_counters(struct kunit test) +{ + unsigned int orig_l3_num_allocated_mbwu = l3_num_allocated_mbwu; + u32 orig_mpam_partid_max = mpam_partid_max; + u32 orig_mpam_pmg_max = mpam_pmg_max; + bool orig_cdp_enabled = cdp_enabled; + struct rdt_resource fake_l3; + + /* Force there to be some PARTID/PMG / + mpam_partid_max = 3; + mpam_pmg_max = 1; + + cdp_enabled = false; + + / ABMC off, CDP off / + l3_num_allocated_mbwu = resctrl_arch_system_num_rmid_idx(); + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, resctrl_arch_system_num_rmid_idx()); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_assign_on_mkdir); + + / ABMC on, CDP off / + l3_num_allocated_mbwu = 4; + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, 4); + KUNIT_EXPECT_TRUE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_TRUE(test, fake_l3.mon.mbm_assign_on_mkdir); + + cdp_enabled = true; + + / ABMC off, CDP on / + l3_num_allocated_mbwu = resctrl_arch_system_num_rmid_idx(); + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + + / (value not consumed by resctrl) / + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, resctrl_arch_system_num_rmid_idx() / 2); + + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_assign_on_mkdir); + + / ABMC on, CDP on / + l3_num_allocated_mbwu = 4; + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, 2); + KUNIT_EXPECT_TRUE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_TRUE(test, fake_l3.mon.mbm_assign_on_mkdir); + + / ABMC 'on', CDP on - but not enough counters / + l3_num_allocated_mbwu = 1; + mpam_resctrl_monitor_sync_abmc_vals(&fake_l3); + KUNIT_EXPECT_EQ(test, fake_l3.mon.num_mbm_cntrs, 0); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_cntr_assignable); + KUNIT_EXPECT_FALSE(test, fake_l3.mon.mbm_assign_on_mkdir); + + / Restore global variables that were messed with */ + l3_num_allocated_mbwu = orig_l3_num_allocated_mbwu; + mpam_partid_max = orig_mpam_partid_max; + mpam_pmg_max = orig_mpam_pmg_max; + cdp_enabled = orig_cdp_enabled; +} + static struct kunit_case mpam_resctrl_test_cases[] = { KUNIT_CASE(test_get_mba_granularity), KUNIT_CASE_PARAM(test_mbw_max_to_percent, test_percent_value_gen_params), @@ -353,6 +414,7 @@ static struct kunit_case mpam_resctrl_test_cases[] = { KUNIT_CASE_PARAM(test_percent_max_roundtrip_stability, test_all_bwa_wd_gen_params), KUNIT_CASE_PARAM(test_rmid_idx_encoding, test_rmid_idx_gen_params), + KUNIT_CASE(test_num_assignable_counters), {} }; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:58:59 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> ABMC has a helper resctrl_arch_config_cntr() for changing the mapping between 'cntr_id' and a CLOSID/RMID pair. Add the helper. For MPAM this is done by updating the mon->mbwu_idx_to_mon[] array, and as usual CDP means it needs doing in three different ways. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- drivers/resctrl/mpam_resctrl.c \| 37 ++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index 2a9efc6c6fae..9198af3221d5 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -776,6 +776,43 @@ static void mpam_resctrl_pick_counters(void) mpam_resctrl_counters[QOS_L3_MBM_TOTAL_EVENT_ID].class); } +static void __config_cntr(struct mpam_resctrl_mon mon, u32 cntr_id, + enum resctrl_conf_type cdp_type, u32 closid, u32 rmid, + bool assign) +{ + u32 mbwu_idx, mon_idx = resctrl_get_config_index(cntr_id, cdp_type); + + closid = resctrl_get_config_index(closid, cdp_type); + mbwu_idx = resctrl_arch_rmid_idx_encode(closid, rmid); + WARN_ON_ONCE(mon_idx > l3_num_allocated_mbwu); + + if (assign) + mon->mbwu_idx_to_mon[mbwu_idx] = mon->assigned_counters[mon_idx]; + else + mon->mbwu_idx_to_mon[mbwu_idx] = -1; +} + +void resctrl_arch_config_cntr(struct rdt_resource r, struct rdt_mon_domain d, + enum resctrl_event_id evtid, u32 rmid, u32 closid, + u32 cntr_id, bool assign) +{ + struct mpam_resctrl_mon mon = &mpam_resctrl_counters[evtid]; + + if (!mon->mbwu_idx_to_mon \|\| !mon->assigned_counters) { + pr_debug("monitor arrays not allocated\n"); + return; + } + + if (cdp_enabled) { + __config_cntr(mon, cntr_id, CDP_CODE, closid, rmid, assign); + __config_cntr(mon, cntr_id, CDP_DATA, closid, rmid, assign); + } else { + __config_cntr(mon, cntr_id, CDP_NONE, closid, rmid, assign); + } + + resctrl_arch_reset_rmid(r, d, closid, rmid, evtid); +} + bool resctrl_arch_mbm_cntr_assign_enabled(struct rdt_resource *r) { if (r != &mpam_resctrl_controls[RDT_RESOURCE_L3].resctrl_res) -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:00 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> When resctrl wants to read a domain's 'QOS_L3_OCCUP', it needs to allocate a monitor on the corresponding resource. Monitors are allocated by class instead of component. MBM monitors are much more complicated, if there are enough monitors, they will be pre-allocated and free-running. If ABMC is in use instead then 'some' are pre-allocated in a different way, and need assigning. Add helpers to allocate a CSU monitor. These helper return an out of range value for MBM counters. Allocating a montitor context is expected to block until hardware resources become available. This only makes sense for QOS_L3_OCCUP as unallocated MBM counters are losing data. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since rfc: USE_RMID_IDX -> USE_PRE_ALLOCATED in comment Remove unnecessary arch_mon_ctx = NULL Changes since v2: Add include of resctrl_types.h as dropped from earlier patch --- drivers/resctrl/mpam_internal.h \| 14 ++++++- drivers/resctrl/mpam_resctrl.c \| 67 +++++++++++++++++++++++++++++++++ include/linux/arm_mpam.h \| 5 +++ 3 files changed, 85 insertions(+), 1 deletion(-) diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index 58076abd5de3..8f73528414af 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -29,6 +29,14 @@ struct platform_device; #define PACKED_FOR_KUNIT #endif +/* + * This 'mon' values must not alias an actual monitor, so must be larger than + * U16_MAX, but not be confused with an errno value, so smaller than + * (u32)-SZ_4K. + * USE_PRE_ALLOCATED is used to avoid confusion with an actual monitor. + / +#define USE_PRE_ALLOCATED (U16_MAX + 1) + static inline bool mpam_is_enabled(void) { return static_branch_likely(&mpam_enabled); @@ -216,7 +224,11 @@ enum mon_filter_options { }; struct mon_cfg { - u16 mon; + / + * mon must be large enough to hold out of range values like + * USE_PRE_ALLOCATED + / + u32 mon; u8 pmg; bool match_pmg; bool csu_exclude_clean; diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index 9198af3221d5..c01419c1a381 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -22,6 +22,8 @@ #include "mpam_internal.h" +DECLARE_WAIT_QUEUE_HEAD(resctrl_mon_ctx_waiters); + / * The classes we've picked to map to resctrl resources, wrapped * in with their resctrl structure. @@ -293,6 +295,71 @@ struct rdt_resource resctrl_arch_get_resource(enum resctrl_res_level l) return &mpam_resctrl_controls[l].resctrl_res; } +static int resctrl_arch_mon_ctx_alloc_no_wait(enum resctrl_event_id evtid) +{ + struct mpam_resctrl_mon mon = &mpam_resctrl_counters[evtid]; + + if (!mon->class) + return -EINVAL; + + switch (evtid) { + case QOS_L3_OCCUP_EVENT_ID: + /* With CDP, one monitor gets used for both code/data reads / + return mpam_alloc_csu_mon(mon->class); + case QOS_L3_MBM_LOCAL_EVENT_ID: + case QOS_L3_MBM_TOTAL_EVENT_ID: + return USE_PRE_ALLOCATED; + default: + return -EOPNOTSUPP; + } +} + +void resctrl_arch_mon_ctx_alloc(struct rdt_resource r, + enum resctrl_event_id evtid) +{ + DEFINE_WAIT(wait); + int ret; + + ret = kmalloc(sizeof(ret), GFP_KERNEL); + if (!ret) + return ERR_PTR(-ENOMEM); + + do { + prepare_to_wait(&resctrl_mon_ctx_waiters, &wait, + TASK_INTERRUPTIBLE); + ret = resctrl_arch_mon_ctx_alloc_no_wait(evtid); + if (ret == -ENOSPC) + schedule(); + } while (ret == -ENOSPC && !signal_pending(current)); + finish_wait(&resctrl_mon_ctx_waiters, &wait); + + return ret; +} + +static void resctrl_arch_mon_ctx_free_no_wait(enum resctrl_event_id evtid, + u32 mon_idx) +{ + struct mpam_resctrl_mon mon = &mpam_resctrl_counters[evtid]; + + if (!mon->class) + return; + + if (evtid == QOS_L3_OCCUP_EVENT_ID) + mpam_free_csu_mon(mon->class, mon_idx); + + wake_up(&resctrl_mon_ctx_waiters); +} + +void resctrl_arch_mon_ctx_free(struct rdt_resource r, + enum resctrl_event_id evtid, void arch_mon_ctx) +{ + u32 mon_idx = (u32 )arch_mon_ctx; + + kfree(arch_mon_ctx); + + resctrl_arch_mon_ctx_free_no_wait(evtid, mon_idx); +} + static bool cache_has_usable_cpor(struct mpam_class class) { struct mpam_props cprops = &class->props; diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h index 7d23c90f077d..e1461e32af75 100644 --- a/include/linux/arm_mpam.h +++ b/include/linux/arm_mpam.h @@ -5,6 +5,7 @@ #define __LINUX_ARM_MPAM_H #include <linux/acpi.h> +#include <linux/resctrl_types.h> #include <linux/types.h> struct mpam_msc; @@ -62,6 +63,10 @@ u32 resctrl_arch_rmid_idx_encode(u32 closid, u32 rmid); void resctrl_arch_rmid_idx_decode(u32 idx, u32 closid, u32 rmid); u32 resctrl_arch_system_num_rmid_idx(void); +struct rdt_resource; +void resctrl_arch_mon_ctx_alloc(struct rdt_resource r, enum resctrl_event_id evtid); +void resctrl_arch_mon_ctx_free(struct rdt_resource r, enum resctrl_event_id evtid, void ctx); + /* * mpam_register_requestor() - Register a requestor with the MPAM driver * @partid_max: The maximum PARTID value the requestor can generate. -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:01 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> resctrl uses resctrl_arch_rmid_read() to read counters. CDP emulation means the counter may need reading in three different ways. The same goes for reset. The helpers behind the resctrl_arch_ functions will be re-used for the ABMC equivalent functions. Add the rounding helper for checking monitor values while we're here. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since rfc: cfg intialisation style code flow at end of read_mon_cdp_safe() Changes since v2: Whitespace changes --- drivers/resctrl/mpam_resctrl.c \| 158 +++++++++++++++++++++++++++++++++ include/linux/arm_mpam.h \| 5 ++ 2 files changed, 163 insertions(+) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index c01419c1a381..921be9b53c00 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -360,6 +360,164 @@ void resctrl_arch_mon_ctx_free(struct rdt_resource r, resctrl_arch_mon_ctx_free_no_wait(evtid, mon_idx); } +static int __read_mon(struct mpam_resctrl_mon mon, struct mpam_component mon_comp, + enum mpam_device_features mon_type, + int mon_idx, + enum resctrl_conf_type cdp_type, u32 closid, u32 rmid, u64 val) +{ + struct mon_cfg cfg; + + if (!mpam_is_enabled()) + return -EINVAL; + + /* Shift closid to account for CDP / + closid = resctrl_get_config_index(closid, cdp_type); + + if (mon_idx == USE_PRE_ALLOCATED) { + int mbwu_idx = resctrl_arch_rmid_idx_encode(closid, rmid); + + mon_idx = mon->mbwu_idx_to_mon[mbwu_idx]; + if (mon_idx == -1) { + if (mpam_resctrl_abmc_enabled()) { + / Report Unassigned / + return -ENOENT; + } + / Report Unavailable / + return -EINVAL; + } + } + + if (irqs_disabled()) { + / Check if we can access this domain without an IPI / + return -EIO; + } + + cfg = (struct mon_cfg) { + .mon = mon_idx, + .match_pmg = true, + .partid = closid, + .pmg = rmid, + }; + + return mpam_msmon_read(mon_comp, &cfg, mon_type, val); +} + +static int read_mon_cdp_safe(struct mpam_resctrl_mon mon, struct mpam_component mon_comp, + enum mpam_device_features mon_type, + int mon_idx, u32 closid, u32 rmid, u64 val) +{ + if (cdp_enabled) { + u64 code_val = 0, data_val = 0; + int err; + + err = __read_mon(mon, mon_comp, mon_type, mon_idx, + CDP_CODE, closid, rmid, &code_val); + if (err) + return err; + + err = __read_mon(mon, mon_comp, mon_type, mon_idx, + CDP_DATA, closid, rmid, &data_val); + if (err) + return err; + + val += code_val + data_val; + return 0; + } + + return __read_mon(mon, mon_comp, mon_type, mon_idx, + CDP_NONE, closid, rmid, val); +} + +/ MBWU when not in ABMC mode, and CSU counters. / +int resctrl_arch_rmid_read(struct rdt_resource r, struct rdt_mon_domain d, + u32 closid, u32 rmid, enum resctrl_event_id eventid, + u64 val, void arch_mon_ctx) +{ + struct mpam_resctrl_dom l3_dom; + struct mpam_component mon_comp; + u32 mon_idx = (u32 )arch_mon_ctx; + enum mpam_device_features mon_type; + struct mpam_resctrl_mon mon = &mpam_resctrl_counters[eventid]; + + resctrl_arch_rmid_read_context_check(); + + if (eventid >= QOS_NUM_EVENTS \|\| !mon->class) + return -EINVAL; + + l3_dom = container_of(d, struct mpam_resctrl_dom, resctrl_mon_dom); + mon_comp = l3_dom->mon_comp[eventid]; + + switch (eventid) { + case QOS_L3_OCCUP_EVENT_ID: + mon_type = mpam_feat_msmon_csu; + break; + case QOS_L3_MBM_LOCAL_EVENT_ID: + case QOS_L3_MBM_TOTAL_EVENT_ID: + mon_type = mpam_feat_msmon_mbwu; + break; + default: + return -EINVAL; + } + + return read_mon_cdp_safe(mon, mon_comp, mon_type, mon_idx, + closid, rmid, val); +} + +static void __reset_mon(struct mpam_resctrl_mon mon, struct mpam_component mon_comp, + int mon_idx, + enum resctrl_conf_type cdp_type, u32 closid, u32 rmid) +{ + struct mon_cfg cfg = { }; + + if (!mpam_is_enabled()) + return; + + /* Shift closid to account for CDP / + closid = resctrl_get_config_index(closid, cdp_type); + + if (mon_idx == USE_PRE_ALLOCATED) { + int mbwu_idx = resctrl_arch_rmid_idx_encode(closid, rmid); + mon_idx = mon->mbwu_idx_to_mon[mbwu_idx]; + } + + if (mon_idx == -1) + return; + cfg.mon = mon_idx; + mpam_msmon_reset_mbwu(mon_comp, &cfg); +} + +static void reset_mon_cdp_safe(struct mpam_resctrl_mon mon, struct mpam_component mon_comp, + int mon_idx, u32 closid, u32 rmid) +{ + if (cdp_enabled) { + __reset_mon(mon, mon_comp, mon_idx, CDP_CODE, closid, rmid); + __reset_mon(mon, mon_comp, mon_idx, CDP_DATA, closid, rmid); + } else { + __reset_mon(mon, mon_comp, mon_idx, CDP_NONE, closid, rmid); + } +} + +/ Called via IPI. Call with read_cpus_lock() held. / +void resctrl_arch_reset_rmid(struct rdt_resource r, struct rdt_mon_domain d, + u32 closid, u32 rmid, enum resctrl_event_id eventid) +{ + struct mpam_resctrl_dom l3_dom; + struct mpam_component mon_comp; + struct mpam_resctrl_mon mon = &mpam_resctrl_counters[eventid]; + + if (!mpam_is_enabled()) + return; + + /* Only MBWU counters are relevant, and for supported event types. / + if (eventid == QOS_L3_OCCUP_EVENT_ID \|\| !mon->class) + return; + + l3_dom = container_of(d, struct mpam_resctrl_dom, resctrl_mon_dom); + mon_comp = l3_dom->mon_comp[eventid]; + + reset_mon_cdp_safe(mon, mon_comp, USE_PRE_ALLOCATED, closid, rmid); +} + static bool cache_has_usable_cpor(struct mpam_class class) { struct mpam_props cprops = &class->props; diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h index e1461e32af75..86d5e326d2bd 100644 --- a/include/linux/arm_mpam.h +++ b/include/linux/arm_mpam.h @@ -67,6 +67,11 @@ struct rdt_resource; void resctrl_arch_mon_ctx_alloc(struct rdt_resource r, enum resctrl_event_id evtid); void resctrl_arch_mon_ctx_free(struct rdt_resource r, enum resctrl_event_id evtid, void ctx); +static inline unsigned int resctrl_arch_round_mon_val(unsigned int val) +{ + return val; +} + /* * mpam_register_requestor() - Register a requestor with the MPAM driver * @partid_max: The maximum PARTID value the requestor can generate. -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:02 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> When used in ABMC mode, resctrl uses a different set of helpers to read and reset the counters. Add these. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- drivers/resctrl/mpam_resctrl.c \| 43 ++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index 921be9b53c00..5adc78f9c96f 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -463,6 +463,28 @@ int resctrl_arch_rmid_read(struct rdt_resource r, struct rdt_mon_domain d, closid, rmid, val); } +/* MBWU counters when in ABMC mode / +int resctrl_arch_cntr_read(struct rdt_resource r, struct rdt_mon_domain d, + u32 closid, u32 rmid, int mon_idx, + enum resctrl_event_id eventid, u64 val) +{ + struct mpam_resctrl_mon mon = &mpam_resctrl_counters[eventid]; + struct mpam_resctrl_dom l3_dom; + struct mpam_component mon_comp; + + if (!mpam_is_enabled()) + return -EINVAL; + + if (eventid == QOS_L3_OCCUP_EVENT_ID \|\| !mon->class) + return -EINVAL; + + l3_dom = container_of(d, struct mpam_resctrl_dom, resctrl_mon_dom); + mon_comp = l3_dom->mon_comp[eventid]; + + return read_mon_cdp_safe(mon, mon_comp, mpam_feat_msmon_mbwu, mon_idx, + closid, rmid, val); +} + static void __reset_mon(struct mpam_resctrl_mon mon, struct mpam_component mon_comp, int mon_idx, enum resctrl_conf_type cdp_type, u32 closid, u32 rmid) @@ -518,6 +540,27 @@ void resctrl_arch_reset_rmid(struct rdt_resource r, struct rdt_mon_domain d, reset_mon_cdp_safe(mon, mon_comp, USE_PRE_ALLOCATED, closid, rmid); } +/ Reset an assigned counter / +void resctrl_arch_reset_cntr(struct rdt_resource r, struct rdt_mon_domain d, + u32 closid, u32 rmid, int cntr_id, + enum resctrl_event_id eventid) +{ + struct mpam_resctrl_mon mon = &mpam_resctrl_counters[eventid]; + struct mpam_resctrl_dom l3_dom; + struct mpam_component mon_comp; + + if (!mpam_is_enabled()) + return; + + if (eventid == QOS_L3_OCCUP_EVENT_ID \|\| !mon->class) + return; + + l3_dom = container_of(d, struct mpam_resctrl_dom, resctrl_mon_dom); + mon_comp = l3_dom->mon_comp[eventid]; + + reset_mon_cdp_safe(mon, mon_comp, USE_PRE_ALLOCATED, closid, rmid); +} + static bool cache_has_usable_cpor(struct mpam_class class) { struct mpam_props cprops = &class->props; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:03 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> resctrl's limbo code needs to be told when the data left in a cache is small enough for the partid+pmg value to be re-allocated. x86 uses the cache size divided by the number of rmid users the cache may have. Do the same, but for the smallest cache, and with the number of partid-and-pmg users. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since v2: Move waiting for cache info into it's own patch --- drivers/resctrl/mpam_resctrl.c \| 35 ++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index 5adc78f9c96f..a6be3ce84241 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -561,6 +561,38 @@ void resctrl_arch_reset_cntr(struct rdt_resource r, struct rdt_mon_domain d, reset_mon_cdp_safe(mon, mon_comp, USE_PRE_ALLOCATED, closid, rmid); } +/* + * The rmid realloc threshold should be for the smallest cache exposed to + * resctrl. + / +static int update_rmid_limits(struct mpam_class class) +{ + u32 num_unique_pmg = resctrl_arch_system_num_rmid_idx(); + struct mpam_props cprops = &class->props; + struct cacheinfo ci; + + lockdep_assert_cpus_held(); + + /* Assume cache levels are the same size for all CPUs... / + ci = get_cpu_cacheinfo_level(smp_processor_id(), class->level); + if (!ci \|\| ci->size == 0) { + pr_debug("Could not read cache size for class %u\n", + class->level); + return -EINVAL; + } + + if (!mpam_has_feature(mpam_feat_msmon_csu, cprops)) + return 0; + + if (!resctrl_rmid_realloc_limit \|\| + ci->size < resctrl_rmid_realloc_limit) { + resctrl_rmid_realloc_limit = ci->size; + resctrl_rmid_realloc_threshold = ci->size / num_unique_pmg; + } + + return 0; +} + static bool cache_has_usable_cpor(struct mpam_class class) { struct mpam_props cprops = &class->props; @@ -1006,6 +1038,9 @@ static void mpam_resctrl_pick_counters(void) / CSU counters only make sense on a cache. */ switch (class->type) { case MPAM_CLASS_CACHE: + if (update_rmid_limits(class)) + continue; + counter_update_class(QOS_L3_OCCUP_EVENT_ID, class); break; default: -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:04 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> A few resctrl features and hooks need to be provided, but aren't needed or supported on MPAM platforms. resctrl has individual hooks to separately enable and disable the closid/partid and rmid/pmg context switching code. For MPAM this is all the same thing, as the value in struct task_struct is used to cache the value that should be written to hardware. arm64's context switching code is enabled once MPAM is usable, but doesn't touch the hardware unless the value has changed. For now event configuration is not supported, and can be turned off by returning 'false' from resctrl_arch_is_evt_configurable(). The new io_alloc feature is not supported either, always return false from the enable helper to indicate and fail the enable. Add this, and empty definitions for the other hooks. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- drivers/resctrl/mpam_resctrl.c \| 27 +++++++++++++++++++++++++++ include/linux/arm_mpam.h \| 9 +++++++++ 2 files changed, 36 insertions(+) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index a6be3ce84241..8e2fea2e51d3 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -103,6 +103,23 @@ bool resctrl_arch_mon_capable(void) return exposed_mon_capable; } +bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt) +{ + return false; +} + +void resctrl_arch_mon_event_config_read(void info) +{ +} + +void resctrl_arch_mon_event_config_write(void info) +{ +} + +void resctrl_arch_reset_rmid_all(struct rdt_resource r, struct rdt_mon_domain d) +{ +} + bool resctrl_arch_get_cdp_enabled(enum resctrl_res_level rid) { switch (rid) { @@ -1129,6 +1146,16 @@ int resctrl_arch_mbm_cntr_assign_set(struct rdt_resource r, bool enable) return -EINVAL; } +int resctrl_arch_io_alloc_enable(struct rdt_resource r, bool enable) +{ + return -EOPNOTSUPP; +} + +bool resctrl_arch_get_io_alloc_enabled(struct rdt_resource r) +{ + return false; +} + static int mpam_resctrl_control_init(struct mpam_resctrl_res res) { struct mpam_class class = res->class; diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h index 86d5e326d2bd..f92a36187a52 100644 --- a/include/linux/arm_mpam.h +++ b/include/linux/arm_mpam.h @@ -67,6 +67,15 @@ struct rdt_resource; void resctrl_arch_mon_ctx_alloc(struct rdt_resource r, enum resctrl_event_id evtid); void resctrl_arch_mon_ctx_free(struct rdt_resource r, enum resctrl_event_id evtid, void ctx); +/ + * The CPU configuration for MPAM is cheap to write, and is only written if it + * has changed. No need for fine grained enables. + */ +static inline void resctrl_arch_enable_mon(void) { } +static inline void resctrl_arch_disable_mon(void) { } +static inline void resctrl_arch_enable_alloc(void) { } +static inline void resctrl_arch_disable_alloc(void) { } + static inline unsigned int resctrl_arch_round_mon_val(unsigned int val) { return val; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:05 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> Enough MPAM support is present to enable ARCH_HAS_CPU_RESCTRL. Let it rip^Wlink! ARCH_HAS_CPU_RESCTRL indicates resctrl can be enabled. It is enabled by the arch code simply because it has 'arch' in its name. This removes ARM_CPU_RESCTRL as a mimic of X86_CPU_RESCTRL. While here, move the ACPI dependency to the driver's Kconfig file. In anticipation of MPAM being useful remove the CONFIG_EXPERT restriction. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- arch/arm64/Kconfig \| 4 ++-- arch/arm64/include/asm/resctrl.h \| 2 ++ drivers/resctrl/Kconfig \| 9 ++++++++- drivers/resctrl/Makefile \| 2 +- 4 files changed, 13 insertions(+), 4 deletions(-) create mode 100644 arch/arm64/include/asm/resctrl.h diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index cdcc5b76a110..baeecb88771d 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -2026,8 +2026,8 @@ config ARM64_TLB_RANGE config ARM64_MPAM bool "Enable support for MPAM" - select ARM64_MPAM_DRIVER if EXPERT # does nothing yet - select ACPI_MPAM if ACPI + select ARM64_MPAM_DRIVER + select ARCH_HAS_CPU_RESCTRL help Memory System Resource Partitioning and Monitoring (MPAM) is an optional extension to the Arm architecture that allows each diff --git a/arch/arm64/include/asm/resctrl.h b/arch/arm64/include/asm/resctrl.h new file mode 100644 index 000000000000..b506e95cf6e3 --- /dev/null +++ b/arch/arm64/include/asm/resctrl.h @@ -0,0 +1,2 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <linux/arm_mpam.h> diff --git a/drivers/resctrl/Kconfig b/drivers/resctrl/Kconfig index c808e0470394..672abea3b03c 100644 --- a/drivers/resctrl/Kconfig +++ b/drivers/resctrl/Kconfig @@ -1,6 +1,7 @@ menuconfig ARM64_MPAM_DRIVER bool "MPAM driver" - depends on ARM64 && ARM64_MPAM && EXPERT + depends on ARM64 && ARM64_MPAM + select ACPI_MPAM if ACPI help Memory System Resource Partitioning and Monitoring (MPAM) driver for System IP, e.g. caches and memory controllers. @@ -22,3 +23,9 @@ config MPAM_KUNIT_TEST If unsure, say N. endif + +config ARM64_MPAM_RESCTRL_FS + bool + default y if ARM64_MPAM_DRIVER && RESCTRL_FS + select RESCTRL_RMID_DEPENDS_ON_CLOSID + select RESCTRL_ASSIGN_FIXED diff --git a/drivers/resctrl/Makefile b/drivers/resctrl/Makefile index 40beaf999582..4f6d0e81f9b8 100644 --- a/drivers/resctrl/Makefile +++ b/drivers/resctrl/Makefile @@ -1,5 +1,5 @@ obj-$(CONFIG_ARM64_MPAM_DRIVER) += mpam.o mpam-y += mpam_devices.o -mpam-$(CONFIG_ARM_CPU_RESCTRL) += mpam_resctrl.o +mpam-$(CONFIG_ARM64_MPAM_RESCTRL_FS) += mpam_resctrl.o ccflags-$(CONFIG_ARM64_MPAM_DRIVER_DEBUG) += -DDEBUG -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:06 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> Now that MPAM links against resctrl, call resctrl_init() to register the filesystem and setup resctrl's structures. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since v2: Use for_each_mpam... error path tidying --- drivers/resctrl/mpam_devices.c \| 32 +++++++++++-- drivers/resctrl/mpam_internal.h \| 4 ++ drivers/resctrl/mpam_resctrl.c \| 82 ++++++++++++++++++++++++++++++++- 3 files changed, 113 insertions(+), 5 deletions(-) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index c2127570cf37..9fbe4fe3b13a 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -73,6 +73,14 @@ static DECLARE_WORK(mpam_broken_work, &mpam_disable); /* When mpam is disabled, the printed reason to aid debugging / static char mpam_disable_reason; +/* + * Whether resctrl has been setup. Used by cpuhp in preference to + * mpam_is_enabled(). The disable call after an error interrupt makes + * mpam_is_enabled() false before the cpuhp callbacks are made. + * Reads/writes should hold mpam_cpuhp_state_lock, (or be cpuhp callbacks). + / +static bool mpam_resctrl_enabled; + / * An MSC is a physical container for controls and monitors, each identified by * their RIS index. These share a base-address, interrupts and some MMIO @@ -1635,7 +1643,7 @@ static int mpam_cpu_online(unsigned int cpu) mpam_reprogram_msc(msc); } - if (mpam_is_enabled()) + if (mpam_resctrl_enabled) return mpam_resctrl_online_cpu(cpu); return 0; @@ -1681,7 +1689,7 @@ static int mpam_cpu_offline(unsigned int cpu) { struct mpam_msc msc; - if (mpam_is_enabled()) + if (mpam_resctrl_enabled) mpam_resctrl_offline_cpu(cpu); guard(srcu)(&mpam_srcu); @@ -2543,6 +2551,7 @@ static void mpam_enable_once(void) } static_branch_enable(&mpam_enabled); + mpam_resctrl_enabled = true; mpam_register_cpuhp_callbacks(mpam_cpu_online, mpam_cpu_offline, "mpam:online"); @@ -2602,24 +2611,39 @@ static void mpam_reset_class(struct mpam_class class) void mpam_disable(struct work_struct ignored) { int idx; + bool do_resctrl_exit; struct mpam_class class; struct mpam_msc msc, tmp; + if (mpam_is_enabled()) + static_branch_disable(&mpam_enabled); + mutex_lock(&mpam_cpuhp_state_lock); if (mpam_cpuhp_state) { cpuhp_remove_state(mpam_cpuhp_state); mpam_cpuhp_state = 0; } + + /* + * Removing the cpuhp state called mpam_cpu_offline() and told resctrl + * all the CPUs are offline. + / + do_resctrl_exit = mpam_resctrl_enabled; + mpam_resctrl_enabled = false; mutex_unlock(&mpam_cpuhp_state_lock); - static_branch_disable(&mpam_enabled); + if (do_resctrl_exit) + mpam_resctrl_exit(); mpam_unregister_irqs(); idx = srcu_read_lock(&mpam_srcu); list_for_each_entry_srcu(class, &mpam_classes, classes_list, - srcu_read_lock_held(&mpam_srcu)) + srcu_read_lock_held(&mpam_srcu)) { mpam_reset_class(class); + if (do_resctrl_exit) + mpam_resctrl_teardown_class(class); + } srcu_read_unlock(&mpam_srcu, idx); mutex_lock(&mpam_list_lock); diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index 8f73528414af..d9f52023d730 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -450,12 +450,16 @@ int mpam_get_cpumask_from_cache_id(unsigned long cache_id, u32 cache_level, #ifdef CONFIG_RESCTRL_FS int mpam_resctrl_setup(void); +void mpam_resctrl_exit(void); int mpam_resctrl_online_cpu(unsigned int cpu); void mpam_resctrl_offline_cpu(unsigned int cpu); +void mpam_resctrl_teardown_class(struct mpam_class class); #else static inline int mpam_resctrl_setup(void) { return 0; } +static inline void mpam_resctrl_exit(void) { } static inline int mpam_resctrl_online_cpu(unsigned int cpu) { return 0; } static inline void mpam_resctrl_offline_cpu(unsigned int cpu) { } +static inline void mpam_resctrl_teardown_class(struct mpam_class class) { } #endif / CONFIG_RESCTRL_FS / / diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index 8e2fea2e51d3..e7b839c478fd 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -70,6 +70,12 @@ static bool cdp_enabled; static bool cacheinfo_ready; static DECLARE_WAIT_QUEUE_HEAD(wait_cacheinfo_ready); +/* + * If resctrl_init() succeeded, resctrl_exit() can be used to remove support + * for the filesystem in the event of an error. + / +static bool resctrl_enabled; + / * L3 local/total may come from different classes - what is the number of MBWU * 'on L3'? @@ -316,6 +322,9 @@ static int resctrl_arch_mon_ctx_alloc_no_wait(enum resctrl_event_id evtid) { struct mpam_resctrl_mon mon = &mpam_resctrl_counters[evtid]; + if (!mpam_is_enabled()) + return -EINVAL; + if (!mon->class) return -EINVAL; @@ -358,6 +367,9 @@ static void resctrl_arch_mon_ctx_free_no_wait(enum resctrl_event_id evtid, { struct mpam_resctrl_mon mon = &mpam_resctrl_counters[evtid]; + if (!mpam_is_enabled()) + return; + if (!mon->class) return; @@ -458,6 +470,9 @@ int resctrl_arch_rmid_read(struct rdt_resource r, struct rdt_mon_domain d, resctrl_arch_rmid_read_context_check(); + if (!mpam_is_enabled()) + return -EINVAL; + if (eventid >= QOS_NUM_EVENTS \|\| !mon->class) return -EINVAL; @@ -1398,6 +1413,9 @@ int resctrl_arch_update_one(struct rdt_resource r, struct rdt_ctrl_domain d, lockdep_assert_cpus_held(); lockdep_assert_irqs_enabled(); + if (!mpam_is_enabled()) + return -EINVAL; + /* * No need to check the CPU as mpam_apply_config() doesn't care, and * resctrl_arch_update_domains() relies on this. @@ -1460,6 +1478,9 @@ int resctrl_arch_update_domains(struct rdt_resource r, u32 closid) lockdep_assert_cpus_held(); lockdep_assert_irqs_enabled(); + if (!mpam_is_enabled()) + return -EINVAL; + list_for_each_entry_rcu(d, &r->ctrl_domains, hdr.list) { for (enum resctrl_conf_type t = 0; t < CDP_NUM_TYPES; t++) { struct resctrl_staged_config cfg = &d->staged_config[t]; @@ -1824,7 +1845,11 @@ int mpam_resctrl_setup(void) return -EOPNOTSUPP; } - /* TODO: call resctrl_init() / + err = resctrl_init(); + if (err) + return err; + + WRITE_ONCE(resctrl_enabled, true); return 0; @@ -1834,6 +1859,61 @@ int mpam_resctrl_setup(void) return err; } +void mpam_resctrl_exit(void) +{ + if (!READ_ONCE(resctrl_enabled)) + return; + + WRITE_ONCE(resctrl_enabled, false); + resctrl_exit(); +} + +static void mpam_resctrl_teardown_mon(struct mpam_resctrl_mon mon, struct mpam_class class) +{ + u32 num_mbwu_mon = l3_num_allocated_mbwu; + + if (!mon->mbwu_idx_to_mon) + return; + + if (mon->assigned_counters) { + __free_mbwu_mon(class, mon->assigned_counters, num_mbwu_mon); + mon->assigned_counters = NULL; + kfree(mon->mbwu_idx_to_mon); + } else { + __free_mbwu_mon(class, mon->mbwu_idx_to_mon, num_mbwu_mon); + } + mon->mbwu_idx_to_mon = NULL; +} + +/ + * The driver is detaching an MSC from this class, if resctrl was using it, + * pull on resctrl_exit(). + / +void mpam_resctrl_teardown_class(struct mpam_class class) +{ + struct mpam_resctrl_res res; + enum resctrl_res_level rid; + struct mpam_resctrl_mon mon; + enum resctrl_event_id eventid; + + might_sleep(); + + for_each_mpam_resctrl_control(res, rid) { + if (res->class == class) { + res->class = NULL; + break; + } + } + for_each_mpam_resctrl_mon(mon, eventid) { + if (mon->class == class) { + mon->class = NULL; + + mpam_resctrl_teardown_mon(mon, class); + break; + } + } +} + static int __init __cacheinfo_ready(void) { cacheinfo_ready = true; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:07 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> MPAM supports a minimum and maximum control for memory bandwidth. The purpose of the minimum control is to give priority to tasks that are below their minimum value. Resctrl only provides one value for the bandwidth configuration, which is used for the maximum. The minimum control is always programmed to zero on hardware that supports it. Generate a minimum bandwidth value that is 5% lower than the value provided by resctrl. This means tasks that are not receiving their target bandwidth can be prioritised by the hardware. For component reset reuse the same calculation so that the default is a value resctrl can set. CC: Zeng Heng <zengheng4@huawei.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since rfc: Add reset_mbw_min Clear min cfg when setting max use mpam_extend_config on component reset Changes since v2: bwa_wd limit to 16 moved to earlier patch restrict scope of min and delta variables move code out of loop so smaller change for quirking min move testing into its own commit --- drivers/resctrl/mpam_devices.c \| 69 ++++++++++++++++++++++++++++++--- drivers/resctrl/mpam_internal.h \| 3 ++ drivers/resctrl/mpam_resctrl.c \| 2 + 3 files changed, 69 insertions(+), 5 deletions(-) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index 9fbe4fe3b13a..37bd8efc6ecf 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -1394,8 +1394,12 @@ static void mpam_reprogram_ris_partid(struct mpam_msc_ris ris, u16 partid, } if (mpam_has_feature(mpam_feat_mbw_min, rprops) && - mpam_has_feature(mpam_feat_mbw_min, cfg)) - mpam_write_partsel_reg(msc, MBW_MIN, 0); + mpam_has_feature(mpam_feat_mbw_min, cfg)) { + if (cfg->reset_mbw_min) + mpam_write_partsel_reg(msc, MBW_MIN, 0); + else + mpam_write_partsel_reg(msc, MBW_MIN, cfg->mbw_min); + } if (mpam_has_feature(mpam_feat_mbw_max, rprops) && mpam_has_feature(mpam_feat_mbw_max, cfg)) { @@ -1510,6 +1514,7 @@ static void mpam_init_reset_cfg(struct mpam_config reset_cfg) .reset_cpbm = true, .reset_mbw_pbm = true, .reset_mbw_max = true, + .reset_mbw_min = true, }; bitmap_fill(reset_cfg->features, MPAM_FEATURE_LAST); } @@ -2408,6 +2413,45 @@ static void __destroy_component_cfg(struct mpam_component comp) } } +static void mpam_extend_config(struct mpam_class class, struct mpam_config cfg) +{ + struct mpam_props cprops = &class->props; + u16 min_hw_granule, max_hw_value, res0_bits; + + /* + * Calculate the values the 'min' control can hold. + * e.g. on a platform with bwa_wd = 8, min_hw_granule is 0x00ff because + * those bits are RES0. Configurations of this value are effectively + * zero. But configurations need to saturate at min_hw_granule on + * systems with mismatched bwa_wd, where the 'less than 0' values are + * implemented on some MSC, but not others. + / + res0_bits = 16 - cprops->bwa_wd; + max_hw_value = ((1 << cprops->bwa_wd) - 1) << res0_bits; + min_hw_granule = ~max_hw_value; + + / + * MAX and MIN should be set together. If only one is provided, + * generate a configuration for the other. If only one control + * type is supported, the other value will be ignored. + * + * Resctrl can only configure the MAX. + / + if (mpam_has_feature(mpam_feat_mbw_max, cfg) && + !mpam_has_feature(mpam_feat_mbw_min, cfg)) { + u16 min, delta; + + delta = ((5 MPAMCFG_MBW_MAX_MAX) / 100) - 1; + if (cfg->mbw_max > delta) + min = cfg->mbw_max - delta; + else + min = 0; + + cfg->mbw_min = max(min, min_hw_granule); + mpam_set_feature(mpam_feat_mbw_min, cfg); + } +} + static void mpam_reset_component_cfg(struct mpam_component comp) { int i; @@ -2426,6 +2470,8 @@ static void mpam_reset_component_cfg(struct mpam_component comp) comp->cfg[i].mbw_pbm = GENMASK(cprops->mbw_pbm_bits - 1, 0); if (cprops->bwa_wd) comp->cfg[i].mbw_max = GENMASK(15, 16 - cprops->bwa_wd); + + mpam_extend_config(comp->class, &comp->cfg[i]); } } @@ -2701,24 +2747,37 @@ static bool mpam_update_config(struct mpam_config cfg, maybe_update_config(cfg, mpam_feat_cpor_part, newcfg, cpbm, has_changes); maybe_update_config(cfg, mpam_feat_mbw_part, newcfg, mbw_pbm, has_changes); maybe_update_config(cfg, mpam_feat_mbw_max, newcfg, mbw_max, has_changes); + maybe_update_config(cfg, mpam_feat_mbw_min, newcfg, mbw_min, has_changes); return has_changes; } int mpam_apply_config(struct mpam_component comp, u16 partid, - struct mpam_config cfg) + struct mpam_config user_cfg) { struct mpam_write_config_arg arg; struct mpam_msc_ris ris; + struct mpam_config cfg; struct mpam_vmsc vmsc; struct mpam_msc msc; lockdep_assert_cpus_held(); / Don't pass in the current config! / - WARN_ON_ONCE(&comp->cfg[partid] == cfg); + WARN_ON_ONCE(&comp->cfg[partid] == user_cfg); + + / + * Copy the config to avoid writing back the 'extended' version to + * the caller. + * This avoids mpam_devices.c setting a mbm_min that mpam_resctrl.c + * is unaware of ... when it then changes mbm_max to be lower than + * mbm_min. + / + cfg = user_cfg; + + mpam_extend_config(comp->class, &cfg); - if (!mpam_update_config(&comp->cfg[partid], cfg)) + if (!mpam_update_config(&comp->cfg[partid], &cfg)) return 0; arg.comp = comp; diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index d9f52023d730..69cb75616561 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -278,10 +278,12 @@ struct mpam_config { u32 cpbm; u32 mbw_pbm; u16 mbw_max; + u16 mbw_min; bool reset_cpbm; bool reset_mbw_pbm; bool reset_mbw_max; + bool reset_mbw_min; struct mpam_garbage garbage; }; @@ -618,6 +620,7 @@ static inline void mpam_resctrl_teardown_class(struct mpam_class class) { } MPAMCFG_MBW_MAX - MPAM memory maximum bandwidth partitioning configuration * register / +#define MPAMCFG_MBW_MAX_MAX_NR_BITS 16 #define MPAMCFG_MBW_MAX_MAX GENMASK(15, 0) #define MPAMCFG_MBW_MAX_HARDLIM BIT(31) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index e7b839c478fd..019f7a1d74fd 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -1446,6 +1446,8 @@ int resctrl_arch_update_one(struct rdt_resource r, struct rdt_ctrl_domain d, if (mpam_has_feature(mpam_feat_mbw_max, cprops)) { cfg.mbw_max = percent_to_mbw_max(cfg_val, cprops); mpam_set_feature(mpam_feat_mbw_max, &cfg); + / Allow the min to be calculated from the max */ + mpam_clear_feature(mpam_feat_mbw_min, &cfg); break; } fallthrough; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:08 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	By default we generate a minimum bandwidth value that is 5% lower than the maximum bandwidth value given by resctrl. Add a test for this. Signed-off-by: James Morse <james.morse@arm.com> [horgan: Split test into separate patch] Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- drivers/resctrl/test_mpam_devices.c \| 66 +++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) diff --git a/drivers/resctrl/test_mpam_devices.c b/drivers/resctrl/test_mpam_devices.c index 3e8d564a0c64..2f802fd9f249 100644 --- a/drivers/resctrl/test_mpam_devices.c +++ b/drivers/resctrl/test_mpam_devices.c @@ -322,6 +322,71 @@ static void test_mpam_enable_merge_features(struct kunit test) mutex_unlock(&mpam_list_lock); } +static void test_mpam_extend_config(struct kunit test) +{ + struct mpam_config fake_cfg = { }; + struct mpam_class fake_class = { }; + + /* Configurations with both are not modified / + fake_class.props.bwa_wd = 16; + fake_cfg.mbw_max = 0xfeef; + fake_cfg.mbw_min = 0xfeef; + bitmap_zero(fake_cfg.features, MPAM_FEATURE_LAST); + mpam_set_feature(mpam_feat_mbw_max, &fake_cfg); + mpam_set_feature(mpam_feat_mbw_min, &fake_cfg); + mpam_extend_config(&fake_class, &fake_cfg); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_max, &fake_cfg)); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_min, &fake_cfg)); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_max, 0xfeef); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_min, 0xfeef); + + / When a min is missing, it is generated / + fake_class.props.bwa_wd = 16; + fake_cfg.mbw_max = 0xfeef; + fake_cfg.mbw_min = 0; + bitmap_zero(fake_cfg.features, MPAM_FEATURE_LAST); + mpam_set_feature(mpam_feat_mbw_max, &fake_cfg); + mpam_extend_config(&fake_class, &fake_cfg); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_max, &fake_cfg)); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_min, &fake_cfg)); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_max, 0xfeef); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_min, 0xf224); + + fake_class.props.bwa_wd = 8; + fake_cfg.mbw_max = 0xfeef; + fake_cfg.mbw_min = 0; + bitmap_zero(fake_cfg.features, MPAM_FEATURE_LAST); + mpam_set_feature(mpam_feat_mbw_max, &fake_cfg); + mpam_extend_config(&fake_class, &fake_cfg); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_max, &fake_cfg)); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_min, &fake_cfg)); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_max, 0xfeef); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_min, 0xf224); + + / 5% below the minimum granule, is still the minimum granule / + fake_class.props.bwa_wd = 12; + fake_cfg.mbw_max = 0xf; + fake_cfg.mbw_min = 0; + bitmap_zero(fake_cfg.features, MPAM_FEATURE_LAST); + mpam_set_feature(mpam_feat_mbw_max, &fake_cfg); + mpam_extend_config(&fake_class, &fake_cfg); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_max, &fake_cfg)); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_min, &fake_cfg)); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_max, 0xf); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_min, 0xf); + + fake_class.props.bwa_wd = 16; + fake_cfg.mbw_max = 0x4; + fake_cfg.mbw_min = 0; + bitmap_zero(fake_cfg.features, MPAM_FEATURE_LAST); + mpam_set_feature(mpam_feat_mbw_max, &fake_cfg); + mpam_extend_config(&fake_class, &fake_cfg); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_max, &fake_cfg)); + KUNIT_EXPECT_TRUE(test, mpam_has_feature(mpam_feat_mbw_min, &fake_cfg)); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_max, 0x4); + KUNIT_EXPECT_EQ(test, fake_cfg.mbw_min, 0x0); +} + static void test_mpam_reset_msc_bitmap(struct kunit test) { char __iomem *buf = kunit_kzalloc(test, SZ_16K, GFP_KERNEL); @@ -378,6 +443,7 @@ static struct kunit_case mpam_devices_test_cases[] = { KUNIT_CASE(test_mpam_reset_msc_bitmap), KUNIT_CASE(test_mpam_enable_merge_features), KUNIT_CASE(test__props_mismatch), + KUNIT_CASE(test_mpam_extend_config), {} }; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:09 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: Shanker Donthineni <sdonthineni@nvidia.com> The MPAM specification includes the MPAMF_IIDR, which serves to uniquely identify the MSC implementation through a combination of implementer details, product ID, variant, and revision. Certain hardware issues/errata can be resolved using software workarounds. Introduce a quirk framework to allow workarounds to be enabled based on the MPAMF_IIDR value. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Co-developed-by: Shanker Donthineni <sdonthineni@nvidia.com> Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com> Co-developed-by: James Morse <james.morse@arm.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes by James: Stash the IIDR so this doesn't need an IPI, enable quirks only once, move the description to the callback so it can be pr_once()d, add an enum of workarounds for popular errata. Add macros for making lists of product/revision/vendor half readable Changes since rfc: remove trailing commas in last element of enums Make mpam_enable_quirks() in charge of mpam_set_quirk() even if there is an enable. --- drivers/resctrl/mpam_devices.c \| 32 ++++++++++++++++++++++++++++++++ drivers/resctrl/mpam_internal.h \| 25 +++++++++++++++++++++++++ 2 files changed, 57 insertions(+) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index 37bd8efc6ecf..5f741df9abcc 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -630,6 +630,30 @@ static struct mpam_msc_ris mpam_get_or_create_ris(struct mpam_msc msc, return ERR_PTR(-ENOENT); } +static const struct mpam_quirk mpam_quirks[] = { + { NULL } /* Sentinel / +}; + +static void mpam_enable_quirks(struct mpam_msc msc) +{ + const struct mpam_quirk quirk; + + for (quirk = &mpam_quirks[0]; quirk->iidr_mask; quirk++) { + int err = 0; + + if (quirk->iidr != (msc->iidr & quirk->iidr_mask)) + continue; + + if (quirk->init) + err = quirk->init(msc, quirk); + + if (err) + continue; + + mpam_set_quirk(quirk->workaround, msc); + } +} + / * IHI009A.a has this nugget: "If a monitor does not support automatic behaviour * of NRDY, software can use this bit for any purpose" - so hardware might not @@ -864,8 +888,11 @@ static int mpam_msc_hw_probe(struct mpam_msc msc) / Grab an IDR value to find out how many RIS there are / mutex_lock(&msc->part_sel_lock); idr = mpam_msc_read_idr(msc); + msc->iidr = mpam_read_partsel_reg(msc, IIDR); mutex_unlock(&msc->part_sel_lock); + mpam_enable_quirks(msc); + msc->ris_max = FIELD_GET(MPAMF_IDR_RIS_MAX, idr); / Use these values so partid/pmg always starts with a valid value / @@ -1993,6 +2020,7 @@ static bool mpam_has_cmax_wd_feature(struct mpam_props props) * resulting safe value must be compatible with both. When merging values in * the tree, all the aliasing resources must be handled first. * On mismatch, parent is modified. + * Quirks on an MSC will apply to all MSC in that class. / static void __props_mismatch(struct mpam_props parent, struct mpam_props child, bool alias) @@ -2112,6 +2140,7 @@ static void __props_mismatch(struct mpam_props parent, * nobble the class feature, as we can't configure all the resources. * e.g. The L3 cache is composed of two resources with 13 and 17 portion * bitmaps respectively. + * Quirks on an MSC will apply to all MSC in that class. / static void __class_props_mismatch(struct mpam_class class, struct mpam_vmsc vmsc) @@ -2125,6 +2154,9 @@ __class_props_mismatch(struct mpam_class class, struct mpam_vmsc vmsc) dev_dbg(dev, "Merging features for class:0x%lx &= vmsc:0x%lx\n", (long)cprops->features, (long)vprops->features); + / Merge quirks / + class->quirks \|= vmsc->msc->quirks; + / Take the safe value for any common features / __props_mismatch(cprops, vprops, false); } diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index 69cb75616561..d60a3caf6f6e 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -85,6 +85,8 @@ struct mpam_msc { u8 pmg_max; unsigned long ris_idxs; u32 ris_max; + u32 iidr; + u16 quirks; / * error_irq_lock is taken when registering/unregistering the error @@ -216,6 +218,28 @@ struct mpam_props { #define mpam_set_feature(_feat, x) __set_bit(_feat, (x)->features) #define mpam_clear_feature(_feat, x) __clear_bit(_feat, (x)->features) +/* Workaround bits for msc->quirks / +enum mpam_device_quirks { + MPAM_QUIRK_LAST +}; + +#define mpam_has_quirk(_quirk, x) ((1 << (_quirk) & (x)->quirks)) +#define mpam_set_quirk(_quirk, x) ((x)->quirks \|= (1 << (_quirk))) + +struct mpam_quirk { + int (init)(struct mpam_msc msc, const struct mpam_quirk quirk); + + u32 iidr; + u32 iidr_mask; + + enum mpam_device_quirks workaround; +}; + +#define MPAM_IIDR_MATCH_ONE FIELD_PREP_CONST(MPAMF_IIDR_PRODUCTID, 0xfff) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_VARIANT, 0xf) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0xf) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0xfff) + /* The values for MSMON_CFG_MBWU_FLT.RWBW */ enum mon_filter_options { COUNT_BOTH = 0, @@ -259,6 +283,7 @@ struct mpam_class { struct mpam_props props; u32 nrdy_usec; + u16 quirks; u8 level; enum mpam_class_types type; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:10 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: Shanker Donthineni <sdonthineni@nvidia.com> The MPAM bandwidth partitioning controls will not be correctly configured, and hardware will retain default configuration register values, meaning generally that bandwidth will remain unprovisioned. To address the issue, follow the below steps after updating the MBW_MIN and/or MBW_MAX registers. - Perform 64b reads from all 12 bridge MPAM shadow registers at offsets (0x360048 + slice0x10000 + partid8). These registers are read-only. - Continue iterating until all 12 shadow register values match in a loop. pr_warn_once if the values fail to match within the loop count 1000. - Perform 64b writes with the value 0x0 to the two spare registers at offsets 0x1b0000 and 0x1c0000. In the hardware, writes to the MPAMCFG_MBW_MAX MPAMCFG_MBW_MIN registers are transformed into broadcast writes to the 12 shadow registers. The final two writes to the spare registers cause a final rank of downstream micro-architectural MPAM registers to be updated from the shadow copies. The intervening loop to read the 12 shadow registers helps avoid a race condition where writes to the spare registers occur before all shadow registers have been updated. [ morse: Merged the min/max update into a single mpam_quirk_post_config_change() helper. Stashed the t241_id in the msc instead of carrying the physical address around. Test the msc quirk bit instead of a static key. ] Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since rfc: MPAM_IIDR_NVIDIA_T421 -> MPAM_IIDR_NVIDIA_T241 return err from init Be specific about the errata in the init name, mpam_enable_quirk_nvidia_t241 -> mpam_enable_quirk_nvidia_t241_1 --- Documentation/arch/arm64/silicon-errata.rst \| 2 + drivers/resctrl/mpam_devices.c \| 88 +++++++++++++++++++++ drivers/resctrl/mpam_internal.h \| 9 +++ 3 files changed, 99 insertions(+) diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst index a7ec57060f64..4e86b85fe3d6 100644 --- a/Documentation/arch/arm64/silicon-errata.rst +++ b/Documentation/arch/arm64/silicon-errata.rst @@ -246,6 +246,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ \| NVIDIA \| T241 GICv3/4.x \| T241-FABRIC-4 \| N/A \| +----------------+-----------------+-----------------+-----------------------------+ +\| NVIDIA \| T241 MPAM \| T241-MPAM-1 \| N/A \| ++----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ \| Freescale/NXP \| LS2080A/LS1043A \| A-008585 \| FSL_ERRATUM_A008585 \| +----------------+-----------------+-----------------+-----------------------------+ diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index 5f741df9abcc..bdf13a22d98f 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -29,6 +29,16 @@ #include "mpam_internal.h" +/* Values for the T241 errata workaround / +#define T241_CHIPS_MAX 4 +#define T241_CHIP_NSLICES 12 +#define T241_SPARE_REG0_OFF 0x1b0000 +#define T241_SPARE_REG1_OFF 0x1c0000 +#define T241_CHIP_ID(phys) FIELD_GET(GENMASK_ULL(44, 43), phys) +#define T241_SHADOW_REG_OFF(sidx, pid) (0x360048 + (sidx) 0x10000 + (pid) * 8) +#define SMCCC_SOC_ID_T241 0x036b0241 +static void __iomem t241_scratch_regs[T241_CHIPS_MAX]; + / * mpam_list_lock protects the SRCU lists when writing. Once the * mpam_enabled key is enabled these lists are read-only, @@ -630,7 +640,45 @@ static struct mpam_msc_ris mpam_get_or_create_ris(struct mpam_msc msc, return ERR_PTR(-ENOENT); } +static int mpam_enable_quirk_nvidia_t241_1(struct mpam_msc msc, + const struct mpam_quirk quirk) +{ + s32 soc_id = arm_smccc_get_soc_id_version(); + struct resource r; + phys_addr_t phys; + + / + * A mapping to a device other than the MSC is needed, check + * SOC_ID is NVIDIA T241 chip (036b:0241) + / + if (soc_id < 0 \|\| soc_id != SMCCC_SOC_ID_T241) + return -EINVAL; + + r = platform_get_resource(msc->pdev, IORESOURCE_MEM, 0); + if (!r) + return -EINVAL; + + / Find the internal registers base addr from the CHIP ID / + msc->t241_id = T241_CHIP_ID(r->start); + phys = FIELD_PREP(GENMASK_ULL(45, 44), msc->t241_id) \| 0x19000000ULL; + + t241_scratch_regs[msc->t241_id] = ioremap(phys, SZ_8M); + if (WARN_ON_ONCE(!t241_scratch_regs[msc->t241_id])) + return -EINVAL; + + pr_info_once("Enabled workaround for NVIDIA T241 erratum T241-MPAM-1\n"); + + return 0; +} + static const struct mpam_quirk mpam_quirks[] = { + { + / NVIDIA t241 erratum T241-MPAM-1 / + .init = mpam_enable_quirk_nvidia_t241_1, + .iidr = MPAM_IIDR_NVIDIA_T241, + .iidr_mask = MPAM_IIDR_MATCH_ONE, + .workaround = T241_SCRUB_SHADOW_REGS, + }, { NULL } / Sentinel / }; @@ -1378,6 +1426,44 @@ static void mpam_reset_msc_bitmap(struct mpam_msc msc, u16 reg, u16 wd) __mpam_write_reg(msc, reg, bm); } +static void mpam_apply_t241_erratum(struct mpam_msc_ris ris, u16 partid) +{ + int sidx, i, lcount = 1000; + void __iomem regs; + u64 val0, val; + + regs = t241_scratch_regs[ris->vmsc->msc->t241_id]; + + for (i = 0; i < lcount; i++) { + /* Read the shadow register at index 0 / + val0 = readq_relaxed(regs + T241_SHADOW_REG_OFF(0, partid)); + + / Check if all the shadow registers have the same value / + for (sidx = 1; sidx < T241_CHIP_NSLICES; sidx++) { + val = readq_relaxed(regs + + T241_SHADOW_REG_OFF(sidx, partid)); + if (val != val0) + break; + } + if (sidx == T241_CHIP_NSLICES) + break; + } + + if (i == lcount) + pr_warn_once("t241: inconsistent values in shadow regs"); + + / Write a value zero to spare registers to take effect of MBW conf / + writeq_relaxed(0, regs + T241_SPARE_REG0_OFF); + writeq_relaxed(0, regs + T241_SPARE_REG1_OFF); +} + +static void mpam_quirk_post_config_change(struct mpam_msc_ris ris, u16 partid, + struct mpam_config cfg) +{ + if (mpam_has_quirk(T241_SCRUB_SHADOW_REGS, ris->vmsc->msc)) + mpam_apply_t241_erratum(ris, partid); +} + / Called via IPI. Call while holding an SRCU reference / static void mpam_reprogram_ris_partid(struct mpam_msc_ris ris, u16 partid, struct mpam_config cfg) @@ -1465,6 +1551,8 @@ static void mpam_reprogram_ris_partid(struct mpam_msc_ris ris, u16 partid, mpam_write_partsel_reg(msc, PRI, pri_val); } + mpam_quirk_post_config_change(ris, partid, cfg); + mutex_unlock(&msc->part_sel_lock); } diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index d60a3caf6f6e..9d15d37d4b5a 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -130,6 +130,9 @@ struct mpam_msc { void __iomem mapped_hwpage; size_t mapped_hwpage_sz; + / Values only used on some platforms for quirks / + u32 t241_id; + struct mpam_garbage garbage; }; @@ -220,6 +223,7 @@ struct mpam_props { / Workaround bits for msc->quirks / enum mpam_device_quirks { + T241_SCRUB_SHADOW_REGS, MPAM_QUIRK_LAST }; @@ -240,6 +244,11 @@ struct mpam_quirk { FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0xf) \| \ FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0xfff) +#define MPAM_IIDR_NVIDIA_T241 FIELD_PREP_CONST(MPAMF_IIDR_PRODUCTID, 0x241) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_VARIANT, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0x36b) + / The values for MSMON_CFG_MBWU_FLT.RWBW */ enum mon_filter_options { COUNT_BOTH = 0, -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:11 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: Shanker Donthineni <sdonthineni@nvidia.com> In the T241 implementation of memory-bandwidth partitioning, in the absence of contention for bandwidth, the minimum bandwidth setting can affect the amount of achieved bandwidth. Specifically, the achieved bandwidth in the absence of contention can settle to any value between the values of MPAMCFG_MBW_MIN and MPAMCFG_MBW_MAX. Also, if MPAMCFG_MBW_MIN is set zero (below 0.78125%), once a core enters a throttled state, it will never leave that state. The first issue is not a concern if the MPAM software allows to program MPAMCFG_MBW_MIN through the sysfs interface. This patch ensures program MBW_MIN=1 (0.78125%) whenever MPAMCFG_MBW_MIN=0 is programmed. In the scenario where the resctrl doesn't support the MBW_MIN interface via sysfs, to achieve bandwidth closer to MBW_MAX in the absence of contention, software should configure a relatively narrow gap between MBW_MIN and MBW_MAX. The recommendation is to use a 5% gap to mitigate the problem. [ morse: Added as second quirk, adapted to use the new intermediate values in mpam_extend_config() ] Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since rfc: MPAM_IIDR_NVIDIA_T421 -> MPAM_IIDR_NVIDIA_T241 Handling when reset_mbw_min is set --- Documentation/arch/arm64/silicon-errata.rst \| 2 ++ drivers/resctrl/mpam_devices.c \| 34 +++++++++++++++++++-- drivers/resctrl/mpam_internal.h \| 1 + 3 files changed, 34 insertions(+), 3 deletions(-) diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst index 4e86b85fe3d6..b18bc704d4a1 100644 --- a/Documentation/arch/arm64/silicon-errata.rst +++ b/Documentation/arch/arm64/silicon-errata.rst @@ -248,6 +248,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ \| NVIDIA \| T241 MPAM \| T241-MPAM-1 \| N/A \| +----------------+-----------------+-----------------+-----------------------------+ +\| NVIDIA \| T241 MPAM \| T241-MPAM-4 \| N/A \| ++----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ \| Freescale/NXP \| LS2080A/LS1043A \| A-008585 \| FSL_ERRATUM_A008585 \| +----------------+-----------------+-----------------+-----------------------------+ diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index bdf13a22d98f..884ca6a6d8f3 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -679,6 +679,12 @@ static const struct mpam_quirk mpam_quirks[] = { .iidr_mask = MPAM_IIDR_MATCH_ONE, .workaround = T241_SCRUB_SHADOW_REGS, }, + { + /* NVIDIA t241 erratum T241-MPAM-4 / + .iidr = MPAM_IIDR_NVIDIA_T241, + .iidr_mask = MPAM_IIDR_MATCH_ONE, + .workaround = T241_FORCE_MBW_MIN_TO_ONE, + }, { NULL } / Sentinel / }; @@ -1464,6 +1470,17 @@ static void mpam_quirk_post_config_change(struct mpam_msc_ris ris, u16 partid, mpam_apply_t241_erratum(ris, partid); } +static u16 mpam_wa_t241_force_mbw_min_to_one(struct mpam_props props) +{ + u16 max_hw_value, min_hw_granule, res0_bits; + + res0_bits = 16 - props->bwa_wd; + max_hw_value = ((1 << props->bwa_wd) - 1) << res0_bits; + min_hw_granule = ~max_hw_value; + + return min_hw_granule + 1; +} + / Called via IPI. Call while holding an SRCU reference / static void mpam_reprogram_ris_partid(struct mpam_msc_ris ris, u16 partid, struct mpam_config cfg) @@ -1508,10 +1525,15 @@ static void mpam_reprogram_ris_partid(struct mpam_msc_ris ris, u16 partid, if (mpam_has_feature(mpam_feat_mbw_min, rprops) && mpam_has_feature(mpam_feat_mbw_min, cfg)) { - if (cfg->reset_mbw_min) - mpam_write_partsel_reg(msc, MBW_MIN, 0); - else + if (cfg->reset_mbw_min) { + u16 reset = 0; + + if (mpam_has_quirk(T241_FORCE_MBW_MIN_TO_ONE, msc)) + reset = mpam_wa_t241_force_mbw_min_to_one(rprops); + mpam_write_partsel_reg(msc, MBW_MIN, reset); + } else { mpam_write_partsel_reg(msc, MBW_MIN, cfg->mbw_min); + } } if (mpam_has_feature(mpam_feat_mbw_max, rprops) && @@ -2570,6 +2592,12 @@ static void mpam_extend_config(struct mpam_class class, struct mpam_config cfg cfg->mbw_min = max(min, min_hw_granule); mpam_set_feature(mpam_feat_mbw_min, cfg); } + + if (mpam_has_quirk(T241_FORCE_MBW_MIN_TO_ONE, class) && + cfg->mbw_min <= min_hw_granule) { + cfg->mbw_min = min_hw_granule + 1; + mpam_set_feature(mpam_feat_mbw_min, cfg); + } } static void mpam_reset_component_cfg(struct mpam_component comp) diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index 9d15d37d4b5a..7b4566814945 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -224,6 +224,7 @@ struct mpam_props { / Workaround bits for msc->quirks */ enum mpam_device_quirks { T241_SCRUB_SHADOW_REGS, + T241_FORCE_MBW_MIN_TO_ONE, MPAM_QUIRK_LAST }; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:12 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: Shanker Donthineni <sdonthineni@nvidia.com> The registers MSMON_MBWU_L and MSMON_MBWU return the number of requests rather than the number of bytes transferred. Bandwidth resource monitoring is performed at the last level cache, where each request arrive in 64Byte granularity. The current implementation returns the number of transactions received at the last level cache but does not provide the value in bytes. Scaling by 64 gives an accurate byte count to match the MPAM specification for the MSMON_MBWU and MSMON_MBWU_L registers. This patch fixes the issue by reporting the actual number of bytes instead of the number of transactions from __ris_msmon_read(). Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since rfc: MPAM_IIDR_NVIDIA_T421 -> MPAM_IIDR_NVIDIA_T241 Don't apply workaround to MSMON_MBWU_LWD --- Documentation/arch/arm64/silicon-errata.rst \| 2 ++ drivers/resctrl/mpam_devices.c \| 26 +++++++++++++++++++-- drivers/resctrl/mpam_internal.h \| 1 + 3 files changed, 27 insertions(+), 2 deletions(-) diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst index b18bc704d4a1..e810b2a8f40e 100644 --- a/Documentation/arch/arm64/silicon-errata.rst +++ b/Documentation/arch/arm64/silicon-errata.rst @@ -250,6 +250,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ \| NVIDIA \| T241 MPAM \| T241-MPAM-4 \| N/A \| +----------------+-----------------+-----------------+-----------------------------+ +\| NVIDIA \| T241 MPAM \| T241-MPAM-6 \| N/A \| ++----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ \| Freescale/NXP \| LS2080A/LS1043A \| A-008585 \| FSL_ERRATUM_A008585 \| +----------------+-----------------+-----------------+-----------------------------+ diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index 884ca6a6d8f3..7409cb7edab4 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -685,6 +685,12 @@ static const struct mpam_quirk mpam_quirks[] = { .iidr_mask = MPAM_IIDR_MATCH_ONE, .workaround = T241_FORCE_MBW_MIN_TO_ONE, }, + { + /* NVIDIA t241 erratum T241-MPAM-6 / + .iidr = MPAM_IIDR_NVIDIA_T241, + .iidr_mask = MPAM_IIDR_MATCH_ONE, + .workaround = T241_MBW_COUNTER_SCALE_64, + }, { NULL } / Sentinel / }; @@ -1146,7 +1152,7 @@ static void write_msmon_ctl_flt_vals(struct mon_read m, u32 ctl_val, } } -static u64 mpam_msmon_overflow_val(enum mpam_device_features type) +static u64 __mpam_msmon_overflow_val(enum mpam_device_features type) { /* TODO: implement scaling counters / switch (type) { @@ -1161,6 +1167,18 @@ static u64 mpam_msmon_overflow_val(enum mpam_device_features type) } } +static u64 mpam_msmon_overflow_val(enum mpam_device_features type, + struct mpam_msc msc) +{ + u64 overflow_val = __mpam_msmon_overflow_val(type); + + if (mpam_has_quirk(T241_MBW_COUNTER_SCALE_64, msc) && + type != mpam_feat_msmon_mbwu_63counter) + overflow_val = 64; + + return overflow_val; +} + static void __ris_msmon_read(void arg) { u64 now; @@ -1251,13 +1269,17 @@ static void __ris_msmon_read(void arg) now = FIELD_GET(MSMON___VALUE, now); } + if (mpam_has_quirk(T241_MBW_COUNTER_SCALE_64, msc) && + m->type != mpam_feat_msmon_mbwu_63counter) + now = 64; + if (nrdy) break; mbwu_state = &ris->mbwu_state[ctx->mon]; if (overflow) - mbwu_state->correction += mpam_msmon_overflow_val(m->type); + mbwu_state->correction += mpam_msmon_overflow_val(m->type, msc); /* * Include bandwidth consumed before the last hardware reset and diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index 7b4566814945..1680d1036472 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -225,6 +225,7 @@ struct mpam_props { enum mpam_device_quirks { T241_SCRUB_SHADOW_REGS, T241_FORCE_MBW_MIN_TO_ONE, + T241_MBW_COUNTER_SCALE_64, MPAM_QUIRK_LAST }; -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:13 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	From: James Morse <james.morse@arm.com> CMN-650 is afflicted with an erratum where the CSU NRDY bit never clears. This tells us the monitor never finishes scanning the cache. The erratum document says to wait the maximum time, then ignore the field. Add a flag to indicate whether this is the final attempt to read the counter, and when this quirk is applied, ignore the NRDY field. This means accesses to this counter will always retry, even if the counter was previously programmed to the same values. The counter value is not expected to be stable, it drifts up and down with each allocation and eviction. The CSU register provides the value for a point in time. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Documentation/arch/arm64/silicon-errata.rst \| 3 +++ drivers/resctrl/mpam_devices.c \| 12 ++++++++++++ drivers/resctrl/mpam_internal.h \| 6 ++++++ 3 files changed, 21 insertions(+) diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst index e810b2a8f40e..3667650036fb 100644 --- a/Documentation/arch/arm64/silicon-errata.rst +++ b/Documentation/arch/arm64/silicon-errata.rst @@ -213,6 +213,9 @@ stable kernels. \| ARM \| GIC-700 \| #2941627 \| ARM64_ERRATUM_2941627 \| +----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ +\| ARM \| CMN-650 \| #3642720 \| N/A \| ++----------------+-----------------+-----------------+-----------------------------+ ++----------------+-----------------+-----------------+-----------------------------+ \| Broadcom \| Brahma-B53 \| N/A \| ARM64_ERRATUM_845719 \| +----------------+-----------------+-----------------+-----------------------------+ \| Broadcom \| Brahma-B53 \| N/A \| ARM64_ERRATUM_843419 \| diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index 7409cb7edab4..e6c9ddaa60e2 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -691,6 +691,12 @@ static const struct mpam_quirk mpam_quirks[] = { .iidr_mask = MPAM_IIDR_MATCH_ONE, .workaround = T241_MBW_COUNTER_SCALE_64, }, + { + /* ARM CMN-650 CSU erratum 3642720 / + .iidr = MPAM_IIDR_ARM_CMN_650, + .iidr_mask = MPAM_IIDR_MATCH_ONE, + .workaround = IGNORE_CSU_NRDY, + }, { NULL } / Sentinel / }; @@ -1003,6 +1009,7 @@ struct mon_read { enum mpam_device_features type; u64 val; int err; + bool waited_timeout; }; static bool mpam_ris_has_mbwu_long_counter(struct mpam_msc_ris ris) @@ -1249,6 +1256,10 @@ static void __ris_msmon_read(void arg) if (mpam_has_feature(mpam_feat_msmon_csu_hw_nrdy, rprops)) nrdy = now & MSMON___NRDY; now = FIELD_GET(MSMON___VALUE, now); + + if (mpam_has_quirk(IGNORE_CSU_NRDY, msc) && m->waited_timeout) + nrdy = false; + break; case mpam_feat_msmon_mbwu_31counter: case mpam_feat_msmon_mbwu_44counter: @@ -1386,6 +1397,7 @@ int mpam_msmon_read(struct mpam_component comp, struct mon_cfg ctx, .ctx = ctx, .type = type, .val = val, + .waited_timeout = true, }; val = 0; diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index 1680d1036472..0bd323728b53 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -226,6 +226,7 @@ enum mpam_device_quirks { T241_SCRUB_SHADOW_REGS, T241_FORCE_MBW_MIN_TO_ONE, T241_MBW_COUNTER_SCALE_64, + IGNORE_CSU_NRDY, MPAM_QUIRK_LAST }; @@ -251,6 +252,11 @@ struct mpam_quirk { FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0) \| \ FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0x36b) +#define MPAM_IIDR_ARM_CMN_650 FIELD_PREP_CONST(MPAMF_IIDR_PRODUCTID, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_VARIANT, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0x43b) + / The values for MSMON_CFG_MBWU_FLT.RWBW */ enum mon_filter_options { COUNT_BOTH = 0, -- 2.43.0	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 12 Jan 2026 16:59:14 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/12/26 08:58, Ben Horgan wrote: Reviewed-by: Fenghua Yu <fenghuay@nvidia.com> Thanks. -Fenghua	{ "author": "Fenghua Yu <fenghuay@nvidia.com>", "date": "Mon, 12 Jan 2026 09:13:24 -0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:39 +0000 Ben Horgan <ben.horgan@arm.com> wrote: Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 14:19:16 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:40 +0000 Ben Horgan <ben.horgan@arm.com> wrote: Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> nvhe	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 14:21:04 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Jonathan, On 1/13/26 14:21, Jonathan Cameron wrote: In this case, I do mean arm64_sw.hvhe which is the configuration when kvm-arm.mode=protected. The aliasing of the registers when E2H is set meant that the read_sysreg_s(SYS_MPAM1_EL1) was actually accessing SYS_MPAM2_EL2 and so the read and write were for the same value. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Tue, 13 Jan 2026 14:35:16 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:44 +0000 Ben Horgan <ben.horgan@arm.com> wrote: There was a question from Zhengheng on v2 that doesn't seem to be addressed and I'm not seeing a reply on list. Maybe an email snafu? https://lore.kernel.org/all/20260109034506.1176234-1-zengheng4@huawei.com/ Please +CC zhengheng on future versions if we need them! Thanks, Jonathan	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 14:46:35 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:51 +0000 Ben Horgan <ben.horgan@arm.com> wrote: Much easier to read. Thanks! Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 14:55:40 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Jonathan, Zeng, On 1/13/26 14:46, Jonathan Cameron wrote: Yes, sorry! For some reason I don't get his emails. :( It happened on the base mpam driver series too. I'll keep a better look at lore and reply to his v2 query. Will do. Should be CC'd on this version too. I don't if there is an email issue with that too. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Tue, 13 Jan 2026 14:58:41 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:52 +0000 Ben Horgan <ben.horgan@arm.com> wrote: I'm not sure this particular test brings a massive amount of value, but I'm not one to object to more tests! Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 14:59:55 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:53 +0000 Ben Horgan <ben.horgan@arm.com> wrote: I don't mind the patch but I'm not entirely following this comment. Is the point that previously there was a sneaky user before this was added in the series? Anyhow, that's not in the patch itself so Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 15:01:59 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:54 +0000 Ben Horgan <ben.horgan@arm.com> wrote: Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 15:06:18 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:57 +0000 Ben Horgan <ben.horgan@arm.com> wrote: Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 15:10:25 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Jonathan, On 1/13/26 15:01, Jonathan Cameron wrote: Yes, arm_mpam: resctrl: Add support for 'MB' resource, accesses cacheinfo so wanted to order this patch before that. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Tue, 13 Jan 2026 15:15:43 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:59 +0000 Ben Horgan <ben.horgan@arm.com> wrote: Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 15:26:38 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:59:08 +0000 Ben Horgan <ben.horgan@arm.com> wrote: I'm interested to see how this plays out as a default choice vs what people elect to run. Seems harmless to start with this. Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 15:39:38 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:59:09 +0000 Ben Horgan <ben.horgan@arm.com> wrote: Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Tue, 13 Jan 2026 15:43:36 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, (Please note I am unfamiliar with this code so missing some context.) On 1/12/26 8:58 AM, Ben Horgan wrote: It should not be necessary to offline the control domain if attempt to online it failed but removing it from the ctrl_domains list is necessary. What happens to memory dom points to? This error path is unexpected to me. From what I can tell, if there is a problem initializing the monitor domain this flow will undo both monitor and control domain, even if initialization of control domain was successful. In this case: - Flow jumps to error path from within the if (exposed_mon_capable) block and proceeds to do control domain cleanup without considering whether control domain was initialized or not. That is, does not take exposed_alloc_capable into account - Control domain cleanup seems to be partial, for example, should it remove domain from ctrl_domains list? - On failure there is dom = ERR_PTR(err) but I cannot see where this memory is freed in both the monitor and control domain error paths. On success, should cpu be added to the respective headers' cpumask? Reinette	{ "author": "Reinette Chatre <reinette.chatre@intel.com>", "date": "Tue, 13 Jan 2026 08:49:29 -0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/12/26 8:58 AM, Ben Horgan wrote: fyi ... [1] enabled total memory bandwidth to also be used as input to software controller and additionally enabled user space to set per resource group which memory bandwidth event is used as input to the software controller. Reinette [1] https://lore.kernel.org/all/20241206163148.83828-1-tony.luck@intel.com/	{ "author": "Reinette Chatre <reinette.chatre@intel.com>", "date": "Tue, 13 Jan 2026 14:18:48 -0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/12/26 8:58 AM, Ben Horgan wrote: Reading the above loop and how it is used to call mpam_resctrl_monitor_init() for every event it looks like there is an implicit assumption that MPAM supports all events known to resctrl. Please consider the most recent resctrl feature "telemetry monitoring" currently queued for inclusion: https://lore.kernel.org/lkml/20251217172121.12030-1-tony.luck@intel.com/ (You can find latest resctrl code queued for inclusion on the x86/cache branch of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git) New telemetry monitoring introduces several new events known to resctrl. Specifically, here is how enum resctrl_event_id looks at the moment: /* Event IDs / enum resctrl_event_id { / Must match value of first event below / QOS_FIRST_EVENT = 0x01, / * These values match those used to program IA32_QM_EVTSEL before * reading IA32_QM_CTR on RDT systems. / QOS_L3_OCCUP_EVENT_ID = 0x01, QOS_L3_MBM_TOTAL_EVENT_ID = 0x02, QOS_L3_MBM_LOCAL_EVENT_ID = 0x03, / Intel Telemetry Events / PMT_EVENT_ENERGY, PMT_EVENT_ACTIVITY, PMT_EVENT_STALLS_LLC_HIT, PMT_EVENT_C1_RES, PMT_EVENT_UNHALTED_CORE_CYCLES, PMT_EVENT_STALLS_LLC_MISS, PMT_EVENT_AUTO_C6_RES, PMT_EVENT_UNHALTED_REF_CYCLES, PMT_EVENT_UOPS_RETIRED, / Must be the last / QOS_NUM_EVENTS, }; ... btw, the telemetry work also changed this function prototype to be: bool resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu, unsigned int binary_bits, void arch_priv); If I understand correctly resctrl_enable_mon_event() will be called for every event in enum resctrl_event_id which now contains events that may not actually be supported. I think it may be safer to be specific in which events MPAM wants to enable. The idea of adding a per MON group "num_mon_groups" file has been floated a couple of times now. I have not heard any objections against doing something like this. https://lore.kernel.org/all/cbe665c2-fe83-e446-1696-7115c0f9fd76@arm.com/ https://lore.kernel.org/lkml/46767ca7-1f1b-48e8-8ce6-be4b00d129f9@intel.com/ Reinette	{ "author": "Reinette Chatre <reinette.chatre@intel.com>", "date": "Tue, 13 Jan 2026 15:14:29 -0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Another advantage is that, given the small size of the L2 cache, frequent switching of MPAM configurations between kernel and user modes can cause cache-capacity jitter, making it difficult to isolate interference from noisy neighborhood. However, in addition to the issues mentioned above, updating the MPAM1_EL1 configuration also exposes interrupt handling to the MPAM settings of the current task. I still agree with the current modification of setting MPAM1_EL1 to the same value as MPAM0_EL1. However, the ARM MPAM hardware supports more flexible configuration schemes than x86 RDT and another approach is also worth considering: Software can let a control group choose whether kernel mode follows the user mode MPAM settings, or whether the kernel mode configuration is delegated to the default control group, though this may change the existing user interface. At the LPC resctrl micro-conference, Babu also mentioned the PLZA proposal as an attempt to address the issues raised above. Seems like no clear interface was presented yet. Wait to see what new interface that solution will introduce. One last thing, please add me to the CC list for future MPAM patch series. I'll provide timely testing on my local aarch64 environment and review feedback. Thanks. Best Regards, Zeng Heng	{ "author": "Zeng Heng <zengheng4@huawei.com>", "date": "Wed, 14 Jan 2026 14:51:49 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:39 +0000, Ben Horgan <ben.horgan@arm.com> wrote: What's the rationale for doing this independently of rest of the MPAM stuff in __activate_traps_mpam()? M. -- Without deviation from the norm, progress is not possible.	{ "author": "Marc Zyngier <maz@kernel.org>", "date": "Wed, 14 Jan 2026 12:06:28 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:40 +0000, Ben Horgan <ben.horgan@arm.com> wrote: Is it really OK to not preserve the rest of MPAM2_EL2? This explicitly clears MPAM2_EL2.MPAMEN, which feels counter-productive. M. -- Without deviation from the norm, progress is not possible.	{ "author": "Marc Zyngier <maz@kernel.org>", "date": "Wed, 14 Jan 2026 12:09:14 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Marc, On 1/14/26 12:09, Marc Zyngier wrote: There are 3 things to consider: 1. traps - these are only relevant when we leave EL2 and are dealt with in __activate_traps_mpam(). (This also covers EnMPAMSM which is a not-trap bit.) 2. MPAM2_EL2.MPAMEN - this is read only as long as we have an EL3 and if we don't have EL3 will be 0 anyway from el2_setup.h and MPAM won't be considered supported in the kernel. 3. The alternate partid space fields which are kept as zero and relate to FEAT_RME. So, safe. Ok with you or would you rather I make it more obviously safe? Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Wed, 14 Jan 2026 14:39:58 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Marc, On 1/14/26 12:06, Marc Zyngier wrote: The __activate_traps_mpam() is relevant even for nvhe but __mpam_guest_load() is only need in vhe as otherwise we can rely on MPAM1_EL1 and MPAM0_EL0 having the same partid/pmg configuration (although this MPAM policy will likely become configurable sometime down the line). Besides that it just makes the naming less exact. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Wed, 14 Jan 2026 14:50:22 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Marc, On 1/14/26 14:39, Ben Horgan wrote: As discussed offline, to avoid having to reason about MPAM2_EL2.MPAMEN I'll set this bit to 1 in this write as we are already assuming mpam is enabled and we want to keep it enabled. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Wed, 14 Jan 2026 16:50:50 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Wed, 14 Jan 2026 16:50:50 +0000, Ben Horgan <ben.horgan@arm.com> wrote: Sounds good, thanks. M. -- Without deviation from the norm, progress is not possible.	{ "author": "Marc Zyngier <maz@kernel.org>", "date": "Wed, 14 Jan 2026 17:50:26 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:58 AM, Ben Horgan wrote: Reviewed-by: Gavin Shan <gshan@redhat.com>	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Thu, 15 Jan 2026 10:12:57 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:58 AM, Ben Horgan wrote: Reviewed-by: Gavin Shan <gshan@redhat.com>	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Thu, 15 Jan 2026 10:14:48 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:58 AM, Ben Horgan wrote: Reviewed-by: Gavin Shan <gshan@redhat.com>	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Thu, 15 Jan 2026 10:16:08 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:58 AM, Ben Horgan wrote: Reviewed-by: Gavin Shan <gshan@redhat.com>	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Thu, 15 Jan 2026 10:33:33 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:58 AM, Ben Horgan wrote: Reviewed-by: Gavin Shan <gshan@redhat.com>	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Thu, 15 Jan 2026 10:34:32 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/13/26 12:58 AM, Ben Horgan wrote: With the following nitpick addressed: Reviewed-by: Gavin Shan <gshan@redhat.com> Nitpick: Needn't include those two header files since they have been included to <asm/mpam.h> Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Thu, 15 Jan 2026 14:47:28 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:58 AM, Ben Horgan wrote: Reviewed-by: Gavin Shan <gshan@redhat.com>	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Thu, 15 Jan 2026 14:50:08 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Wed, 14 Jan 2026 14:50:22 +0000, Ben Horgan <ben.horgan@arm.com> wrote: It is completely unclear to me what enforces this. Please point me to the code that does that. Or not. the VM only exists as an extension of userspace, and I don't see on what grounds it should get its own MPAM configuration. I don't care about the naming. I care about how the configuration flow is organised. And so far, this seems extremely messy. Can you please document what gets configured when and in which mode? Thanks, M. -- Without deviation from the norm, progress is not possible.	{ "author": "Marc Zyngier <maz@kernel.org>", "date": "Thu, 15 Jan 2026 09:05:28 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hello Ben, Shouldn't it be return -EOPNOTSUPP;? However, before the function update_rmid_limits() is called, there is a check: if (cache_has_usable_csu(class) && topology_matches_l3(class)). cache_has_usable_csu(class) already contains an identical check. Therefore, I think it's safe to remove this redundant one. Best regards, Shaopeng TAN	{ "author": "\"Shaopeng Tan (Fujitsu)\" <tan.shaopeng@fujitsu.com>", "date": "Thu, 15 Jan 2026 10:05:49 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On Mon, Jan 12, 2026 at 5:59 PM Ben Horgan <ben.horgan@arm.com> wrote: Like before, I applied the patches and successfully booted a kernel on a baremetal Google Cloud C4A instance. I was able to confirm that the resources we expect were present and I was able to successfully run the monitor assignment test cases I used to validate ABMC on AMD systems. (Though I had to hack the driver to pretend there were less MBWU monitors so that the counter assignment interfaces would become available.) My use cases only cover resctrl in the host, so I didn't try any of the KVM integration, but I can at least say there wasn't any evidence that it interfered with resctrl. Tested-by: Peter Newman <peternewman@google.com> Thanks, -Peter	{ "author": "Peter Newman <peternewman@google.com>", "date": "Thu, 15 Jan 2026 12:14:19 +0100", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Marc, On 1/15/26 09:05, Marc Zyngier wrote: The new MPAM arch code always configures kernel space MPAM configuration in tandem, same value to MPAM0_EL1 and MPAM1_EL1 (will access MPAM2_EL2 in vhe). For the cpu part see PATCH v3 07 arm64: mpam: Re-initialise MPAM regs when CPU comes online and for context switching part see PATCH v3 06 arm64: mpam: Context switch the MPAM registers There are no plans to give the VM it's own MPAM configuration. The intent of this patch is to give all the code running in the VM, whether or not it is at EL0 or EL1, uses the MPAM partid/pmg configuration of the userspace VMM that is running it. What I was alluding to here is that if a future host MPAM policy allows the partid/pmg to differ for the kernel and userspace then we won't be able rely on the EL1 configuration matching EL0 in the nvhe case and so would have to copy the host EL0 configuration to EL1 (and add a restore). The goal is that all times the VM runs with the same MPAM partid/pmg configuration as the userspace vmm running it. In VHE: Host kernel configuration is in MPAM2_EL2 Host userspace configuration is in MPAM0_EL1 Guest kernel configuration needs to be in MPAM1_EL1 and so we copy it there from MPAM0_EL1 when switching to the guest. On switching back to the host we can just leave it there as the host doesn't use it. Guest userspace configuration is in MPAM0_EL1, just keep that unchanged. In nVHE: Host kernel configuration is in MPAM1_EL1 Host userspace configuration is in MPAM0_EL1 Once again, guest userspace configuration is in MPAM0_EL1, just keep that unchanged. As host policy ensures MPAM0_EL1 == MPAM1_EL1 for pmg/partid we rely on this to skip changing MPAM1_EL1 on guest entry and to skip the restore on guest exit. I hope this makes the intent clearer. Would you prefer to decouple the kvm handling of the MPAM configuration from the host policy? If so, I expect the MPAM handling can be done together in __activate_traps_mpam(). Thoughts? Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Thu, 15 Jan 2026 11:14:36 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Peter, On 1/15/26 11:14, Peter Newman wrote: [...] Thanks for the testing! Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Thu, 15 Jan 2026 11:36:47 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Thu, 15 Jan 2026 14:47:28 +0800 Gavin Shan <gshan@redhat.com> wrote: I commented on the nitpick. That is a non obvious include chain that we should not rely on. Please keep the headers and continue to follow include what you use style (with exceptions when a given header is clearly documented as always including another like some of the bit map stuff.) It is more obviously correct and causes less grief if headers get refactored in future.	{ "author": "Jonathan Cameron <jonathan.cameron@huawei.com>", "date": "Thu, 15 Jan 2026 12:09:23 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Zeng, +CC Babu (Comments on PLZA) On 1/14/26 06:51, Zeng Heng wrote: Makes sense, thanks for these two observations. I wonder if this would be possible in AMD PLZA as well. Babu? Yes, I watched a recording of that. :) Will do. Apologies for not doing this earlier and thank you for the promise of testing and reviews :) There is a v3 which you have hopefully seen. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Thu, 15 Jan 2026 14:37:31 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Reinette, On 1/13/26 23:14, Reinette Chatre wrote: I'll test against this. [...] Thanks for bringing this to my attention. mpam_resctrl_monitor_init() won't be called for all events known to resctrl as mpam_resctrl_pick_counters() will only set a class for the 3 that MPAM knows about. Still, it is probably best to restrict the iterator to the relevant ones. I will update to use the new signature. As noted above, this only happens for the ones chosen mpam_resctrl_pick_counters(). Hmm, I see now that 'num_rmid' is documented as an upper bound and so neither 1 or mpam_pmg_max + 1 agree with the documentation. " "num_rmids": The number of RMIDs available. This is the upper bound for how many "CTRL_MON" + "MON" groups can be created. " So, if I understand correctly you're proposing setting num_rmids = num_pmg * num_partids on arm platforms and that in the interim this can then be used to calculate the num_pmg by calculating num_closid/num_rmid but that a per CTRL_MON num_mon_groups should be added to make this consistent across architectures? I appreciate that you have shared this resctrl knowledge with me. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Thu, 15 Jan 2026 15:43:54 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On Mon, Jan 12, 2026 at 6:02 PM Ben Horgan <ben.horgan@arm.com> wrote: Are remote memory accesses not cached? How do we know an MBWU monitor residing on a cache won't count remote traffic? Thanks, -Peter	{ "author": "Peter Newman <peternewman@google.com>", "date": "Thu, 15 Jan 2026 16:49:20 +0100", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Shaopeng, On 1/15/26 10:05, Shaopeng Tan (Fujitsu) wrote: The intent of returning 0 here is that if csu is not supported on this class then there is nothing to do and hence no error. Yes, the check is redundant and can be removed. (If it were to stay it should be moved to be before call get_cpu_cacheinfo_level() call so that wouldn't give spurious errors for non-cache cpus.) Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Thu, 15 Jan 2026 16:02:47 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:58:33PM +0000, Ben Horgan wrote: Since we have an isb() already, does it make any difference if we write MPAM0 before the barrier? Similar question for other places where we write these two registers. At some point, we should go through __switch_to() and coalesce the isbs into fewer as we keep accumulating them (e.g. all those switch function setting some sync variable if needed). Is it too expensive to read the MPAM sysregs and avoid carrying around another per-CPU state? You use it for pm restoring but we could just save it in cpu_do_suspend() like other sysregs. Not a big issue, it just feels like this function got unnecessarily complicated (it took me a bit to figure out what it all does). A related question - is resctrl_arch_set_cdp_enabled() always called in non-preemptible contexts? We potentially have a race between setting current->mpam_partid_msg and arm64_mpam_global_default, so the check in mpam_thread_switch() can get confused. And I couldn't figure out where the MPAMx_EL1 registers are written. If any global/per-cpu/per-task value is changed, does the kernel wait until the next thread switch to write the sysreg? The only places I can found touching these sysregs are the thread switch, pm notifiers and KVM. -- Catalin	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Thu, 15 Jan 2026 17:58:15 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:58:30PM +0000, Ben Horgan wrote: Acked-by: Catalin Marinas <catalin.marinas@arm.com>	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Thu, 15 Jan 2026 17:59:05 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:58:34PM +0000, Ben Horgan wrote: Is this comment about priority inversion no longer valid? I see thread switching sets the same value for both MPAM0 and MPAM1 registers but I couldn't find an explanation why this is now better when it wasn't before. MPAM1 will also be inherited by IRQ handlers AFAICT. I mentioned before, is it worth waiting until ERET? Related to this, do LDTR/STTR use MPAM0 or MPAM1? I couldn't figure out from the Arm ARM. If they use MPAM0, then we need the ISB early for the uaccess routines, at least in the thread switching path (an earlier patch). -- Catalin	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Thu, 15 Jan 2026 18:14:09 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:58:35PM +0000, Ben Horgan wrote: Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Thu, 15 Jan 2026 18:16:49 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:58:36PM +0000, Ben Horgan wrote: This looks fine unless we decide to save/restore them in the low-level suspend/resume functions. -- Catalin	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Thu, 15 Jan 2026 18:20:02 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/15/26 7:43 AM, Ben Horgan wrote: ... Please note that this documentation has been refactored (without changing its meaning). The above quoted text is specific to L3 monitoring and with the addition of telemetry monitoring the relevant text now reads: The upper bound for how many "CTRL_MON" + "MON" can be created is the smaller of the L3_MON and PERF_PKG_MON "num_rmids" values. Yes for num_rmids = num_pmg * num_partids. The motivation for this is that to me this looks like the value that best matches the num_rmids documentation. I understand the RMID vs PMG is difficult so my proposal is certainly not set in stone and I would like to hear motivation for different interpretations. "calculating num_pmg" is not obvious though. I interpret "num_pmg" here as number of monitor groups per control group and on an Arm system this is indeed num_closid/num_rmids (if num_rmids = num_pmg * num_partids) but on x86 it is just num_rmids. Having user space depend on such computation to determine how many monitor groups per control group would thus require that user space knows whether the underlying system is Arm or x86 and would go against goal of having resctrl as a generic interface. The way forward may be to deprecate (somehow) num_rmids and transition to something like "num_mon_groups" but it is currently vague how "num_mon_groups" may look like. That thread (https://lore.kernel.org/lkml/46767ca7-1f1b-48e8-8ce6-be4b00d129f9@intel.com/) fizzled out after raising a few options how it may look. Another proposal was to add a "mon_id_includes_control_id" to use as another "guide" to determine how many monitoring groups can be created but at the time it seemed an intermediary step for user to determine the number of monitor groups that resctrl can also provide. https://lore.kernel.org/lkml/CALPaoChad6=xqz+BQQd=dB915xhj1gusmcrS9ya+T2GyhTQc5Q@mail.gmail.com/ Making this consistent across architectures is the goal since resctrl aims to be a generic interface. Users should not need to do things like infer which system they are running on by looking at output of resctrl files as mentioned. fwiw ... there seems to be a usage by Google to compare num_rmids to num_closids to determine how to interact with resctrl: https://lore.kernel.org/lkml/CALPaoCgSO7HzK9BjyM8yL50oPyq9kBj64Nkgyo1WEJrWy5uHUg@mail.gmail.com/ Reinette	{ "author": "Reinette Chatre <reinette.chatre@intel.com>", "date": "Thu, 15 Jan 2026 10:54:45 -0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:58:37PM +0000, Ben Horgan wrote: Do we know for sure that system_supports_sme() returns true at this point (if SME supported)? Digging into the code, system_supports_sme() uses alternative_has_cap_unlikely() which relies on instruction patching. setup_system_capabilities(), IIUC, patches the alternatives after enable_cpu_capabilities(). I think you better use cpus_have_cap(). -- Catalin	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Thu, 15 Jan 2026 19:08:47 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:58:38PM +0000, Ben Horgan wrote: Isn't this function, together with mpam_thread_switch(), in an enclosing #ifdef already? -- Catalin	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Thu, 15 Jan 2026 19:13:45 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:59:06PM +0000, Ben Horgan wrote: Acked-by: Catalin Marinas <catalin.marinas@arm.com>	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Thu, 15 Jan 2026 19:16:48 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi, Shanker and Ben, On 1/12/26 08:59, Ben Horgan wrote: When MBW_MIN=1, min mem bw can be very low when contention. This may drop mem access performance. Is it possible to set MBW_MIN bigger so that ensure the floor of mem access is high? Thanks. -Fenghua	{ "author": "Fenghua Yu <fenghuay@nvidia.com>", "date": "Thu, 15 Jan 2026 15:20:55 -0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Reinette, Peter, On 1/15/26 18:54, Reinette Chatre wrote: Ok, I don't really see another option. The motivation for this is that to me Just thinking about it now but the "mon_id_includes_control_id" option seems the best to me as it is a single bit option that along with "num_rmids" let's you know which monitor groups you can create and if it's sensible to move monitor groups between CTRL MON groups. The "num_mon_groups" per CTRL MON group would also need to be interpreted together with "num_rmid" to know if it is a global or per CTRL MON upper bound. This option also uses multiple files to give the same bit of information. Unfortunately, it looks like we're about to break this heuristic :( At least, until a way to get this information generically in resctrl is decided upon. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Fri, 16 Jan 2026 10:29:01 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hello Ben, $ echo "default" \| sudo tee /sys/fs/resctrl/info/L3_MON/mbm_assign_mode default tee: /sys/fs/resctrl/info/L3_MON/mbm_assign_mode:Invalid argument "return -EOPNOTSUPP;" might be better. Best regards, Shaopeng TAN	{ "author": "\"Shaopeng Tan (Fujitsu)\" <tan.shaopeng@fujitsu.com>", "date": "Fri, 16 Jan 2026 10:34:27 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hello Ben, I ran the MPAM driver on NVIDIA's Grace machine, and it seems to be working fine. Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>	{ "author": "\"Shaopeng Tan (Fujitsu)\" <tan.shaopeng@fujitsu.com>", "date": "Fri, 16 Jan 2026 10:47:40 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Shaopeng, On 1/16/26 10:34, Shaopeng Tan (Fujitsu) wrote: [...] I'll keep this as -EINVAL in the case when 'enable' matches the current mode and change it to return 0 when there is nothing to change. This will match the behaviour once this is handled in resctrl. See the outcome of the discussion on this resctrl patch [1] Note, that I haven't yet updated the patch to match the discussion. Any objection? [1] https://lore.kernel.org/lkml/bf8bb682-6a4d-4f39-916c-952719fcf48d@arm.com/ Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Fri, 16 Jan 2026 11:04:24 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Shaopeng, On 1/16/26 10:47, Shaopeng Tan (Fujitsu) wrote: Thanks for the testing! Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Fri, 16 Jan 2026 11:05:57 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, Jan 12, 2026 at 04:58:29PM +0000, Ben Horgan wrote: After discussing privately, I can see how test__props_mismatch() can end up with unaligned atomics on the mmap_props::features array. Happy to pick it up for 6.19 (probably the first patch as well, though that's harmless). Is there a Fixes tag here for future reference? -- Catalin	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Fri, 16 Jan 2026 11:57:25 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Catalin, On 1/16/26 11:57, Catalin Marinas wrote: Yes please. Yes, the mpam_set/clear macros were introduced in Fixes: 8c90dc68a5de ("arm_mpam: Probe the hardware features resctrl supports") Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Fri, 16 Jan 2026 12:02:06 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/16/26 12:02, Ben Horgan wrote: The mpam_set_clear() actually comes after in: c10ca83a7783 arm_mpam: Merge supported features during mpam_enable() into mpam_class but I think the fixes below is still the correct one as it is where we could first start seeing the problem. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Fri, 16 Jan 2026 12:12:53 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Mon, 12 Jan 2026 16:58:27 +0000, Ben Horgan wrote: Applied to arm64 (for-next/fixes), thanks! [01/47] arm_mpam: Remove duplicate linux/srcu.h header https://git.kernel.org/arm64/c/b5a69c486921 [02/47] arm_mpam: Use non-atomic bitops when modifying feature bitmap https://git.kernel.org/arm64/c/b9f5c38e4af1 -- Catalin	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Fri, 16 Jan 2026 15:47:15 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On Fri, Jan 16, 2026 at 12:12:53PM +0000, Ben Horgan wrote: Yes, I left the original as that's the one first introducing the atomic bitops on this structure. -- Catalin	{ "author": "Catalin Marinas <catalin.marinas@arm.com>", "date": "Fri, 16 Jan 2026 15:51:02 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:58 AM, Ben Horgan wrote: The L3 cache partitioning and MBW (soft) limiting works fine on NVidia's grace-hopper machine. Tested-by: Gavin Shan <gshan@redhat.com> Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 09:30:32 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/13/26 12:58 AM, Ben Horgan wrote: mpam_register_requestor() is exposed until CONFIG_ARM64_MPAM_DRIVER is set. CONFIG_ARM64_MPAM_DRIVER and CONFIG_ARM64_MPAM can be different until PATCH[39/47] is applied. So we need PATCH[39/47] to be applied prior to this patch so that mpam_register_requestor() is always existing and exposed. Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 14:37:46 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:58 AM, Ben Horgan wrote: Reviewed-by: Gavin Shan <gshan@redhat.com>	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 14:40:59 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/13/26 12:58 AM, Ben Horgan wrote: One question below... Need we ensure MPAM capability exists in the hardware before the notifier is registerred? Otherwise, mpam_pm_notifier() can accesses SYS_MPAM0_EL1 and SYS_MPAM1_EL1 system registers which may not supported by the hardware. Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 14:50:16 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/13/26 12:58 AM, Ben Horgan wrote: One nitpick below... Reviewed-by: Gavin Shan <gshan@redhat.com> { } is missed here. Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 14:51:40 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/16/26 3:13 AM, Catalin Marinas wrote: I think Catalin is correct that this ifdef inside mpam_set_task_partid_pmg() can be dropped. Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 14:56:46 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/13/26 12:58 AM, Ben Horgan wrote: Nitpick: Alignment issues in the lines for 2nd/3rd/4th FIELD_PREP(). return FIELD_PREP(...) \| FIELD_PREP(...) \| FIELD_PREP(...) \| FIELD_PREP(...); per_cpu(arm64_mpam_default) won't be reachable until CONFIG_ARM64_MPAM is set. So I think both mpam_set_cpu_defaults() and __mpam_regval() need to be protected by '#ifdef CONFIG_ARM64_MPAM ... #endif'. Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 15:01:41 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/13/26 12:58 AM, Ben Horgan wrote: A warning reported by checkpatch.pl like below. WARNING: Missing a blank line after declarations #117: FILE: drivers/resctrl/mpam_resctrl.c:375: + struct mpam_component *victim_iter; + cpumask_var_t __free(free_cpumask_var) tmp_cpumask; Besides, it'd better to initialize @tmp_cpumask: cpumask_var_t __free(free_cpumask_var) tmp_cpumask = CPUMASK_VAR_NULL; Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 19:53:25 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Ben, On 1/13/26 12:58 AM, Ben Horgan wrote: A warning reported by checkpatch.pl as below. WARNING: Missing a blank line after declarations #84: FILE: drivers/resctrl/mpam_resctrl.c:607: + size_t array_size = num_mbwu_mon * sizeof(int); + int *array __free(kfree) = kmalloc(array_size, GFP_KERNEL); Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 19:57:38 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Peter, On 15/01/2026 15:49, Peter Newman wrote: It will, yes you get double counting. Is forbidding both mbm_total and mbm_local preferable? I think this comes from 'total' in mbm_total not really having the obvious meaning of the word: If I have CPUs in NUMA-A and no memory controllers, then NUMA-B has no CPUs, and all the memory-controllers. With MPAM: we've only got one bandwidth counter, it doesn't know where the traffic goes after the MSC. mbm-local on the L3 would reflect all the bandwidth, and mbm-total on the memory-controllers would have the same number. I think on x86 mbm_local on the CPUs would read zero as zero traffic went to the 'local' memory controller, and mbm_total would reflect all the memory bandwidth. (so 'total' really means 'other') I think what MPAM is doing here is still useful as a system normally has both CPUs and memory controllers in the NUMA nodes, and you can use this to spot a control/monitor group on a NUMA-node that is hammering all the memory (outlier mbm_local), or the same where a NUMA-node's memory controller is getting hammered by all the NUMA nodes (outlier mbm_total) I've not heard of a platform with both memory bandwidth monitors at L3 and the memory controller, so this may be a theoretical issue. Shall we only expose one of mbm-local/total to prevent this being seen by user-space? Thanks, James	{ "author": "James Morse <james.morse@arm.com>", "date": "Mon, 19 Jan 2026 12:04:10 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:59 AM, Ben Horgan wrote: An error reported by checkpatch.pl as below. ERROR: Macros with complex values should be enclosed in parentheses #135: FILE: drivers/resctrl/mpam_internal.h:238: +#define MPAM_IIDR_MATCH_ONE FIELD_PREP_CONST(MPAMF_IIDR_PRODUCTID, 0xfff) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_VARIANT, 0xf) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0xf) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0xfff) Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 20:14:44 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:59 AM, Ben Horgan wrote: An error reported by checkpatch.pl as below. ERROR: Macros with complex values should be enclosed in parentheses #205: FILE: drivers/resctrl/mpam_internal.h:247: +#define MPAM_IIDR_NVIDIA_T241 FIELD_PREP_CONST(MPAMF_IIDR_PRODUCTID, 0x241) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_VARIANT, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0x36b) Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 20:16:30 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	On 1/13/26 12:59 AM, Ben Horgan wrote: An error reported by checkpatch.pl as below. ERROR: Macros with complex values should be enclosed in parentheses #105: FILE: drivers/resctrl/mpam_internal.h:255: +#define MPAM_IIDR_ARM_CMN_650 FIELD_PREP_CONST(MPAMF_IIDR_PRODUCTID, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_VARIANT, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_REVISION, 0) \| \ + FIELD_PREP_CONST(MPAMF_IIDR_IMPLEMENTER, 0x43b) Thanks, Gavin	{ "author": "Gavin Shan <gshan@redhat.com>", "date": "Mon, 19 Jan 2026 20:18:50 +0800", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Catalin, On 1/15/26 17:58, Catalin Marinas wrote: The reason for the isb() placement is to document that it's not required for the MPAM0_EL1. All instructions running at EL1take their MPAM configuration from MPAM1_EL1. This includes LDTR and STTR as you asked about in a different thread. It's done this way as it matches what's done in x86. I expect it would be cheap enough to read the register to check whether a write is required. The resctrl filesystem can only ever get mounted once and resctrl_arch_set_cdp_enabled() is always called in mount. In rdt_get_tree(), rdt_enable_ctx() calls resctrl_arch_set_cdp_enabled(). This is done while holding the rdtgroup_mutex and the user can't change the mpam configuration from the default until the mutex is released and it can claim it. If the task configuration is changed then the MPAM sysreg will only be updated the next time it goes into the kernel. So, just eventually consistent. For cpu configuration, update_closid_rmid() gets called which ipis the cpus and ends up calling mpam_thread_switch() from resctrl_arch_sched_in(). Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 19 Jan 2026 12:23:13 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi James, On Mon, Jan 19, 2026 at 1:04 PM James Morse <james.morse@arm.com> wrote: Our software is going off the definition from the Intel SDM: "This event monitors the L3 external bandwidth satisfied by the local memory. In most platforms that support this event, L3 requests are likely serviced by a memory system with non-uniform memory architecture. This allows bandwidth to off-package memory resources to be tracked by subtracting local from total bandwidth (for instance, bandwidth over QPI to a memory controller on another physical processor could be tracked by subtraction). On NUMA-capable hardware that can support this event where all memory is local, mbm_local == mbm_total, but in practice you can't read them at the same time from userspace, so if you read mbm_total first, you'll probably get a small negative result for remote bandwidth. I believe in the current software design, MPAM is only able to support mbm_total, as an individual MSC (or class of MSCs with the same configuration) can't separate traffic by destination, so it must be the combined value. On a hardware design where MSCs were placed such that one only counts local traffic and another only counts remote, the resctrl MPAM driver would have to understand the hardware configuration well enough to be able to produce counts following Intel's definition of mbm_local and mbm_total. Thanks, -Peter	{ "author": "Peter Newman <peternewman@google.com>", "date": "Mon, 19 Jan 2026 13:47:52 +0100", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Catalin, On 1/15/26 18:14, Catalin Marinas wrote: Yes, will drop it. I see thread I touch on it in the cover letter. It is the way it is done for x86 and so sensible to make it the default. All partids are usable from user-space and user-space can't bypass MPAM controls by doing the work in the kernel. There is a proposal from Babu at AMD, PLZA, which he presented at LPC which would give a new interface to have different configuration, closid, for userspace and kernel space. We should be able to use this with MPAM too. Yes, this is a disadvantage of having MPAM1 and MPAM0 change together. Just for documentation. I can change it if you prefer. They use LDTR/STTR. MPAM doesn't care about which instruction is running. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 19 Jan 2026 13:38:11 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Catalin, On 1/15/26 19:08, Catalin Marinas wrote: I'll switch to cpus_have_cap(). Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 19 Jan 2026 13:40:18 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Gavin, On 1/19/26 11:53, Gavin Shan wrote: [...] I expect this is because __free() declarations don't need to be at the top of a scope and so checkpatch doesn't treat them as normal declarations. I don't think anything needs changing here. Yep, I'll update. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 19 Jan 2026 13:53:23 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Gavin, Jonathan, On 1/15/26 12:09, Jonathan Cameron wrote: Keeping the includes here makes sense to me too. Gavin, are you ok with keeping this as is? Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 19 Jan 2026 14:00:07 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Catalin, On 1/19/26 13:38, Ben Horgan wrote: Ah, that's done in the patch already. Also, we can't treat 0 as special without taking it away from userspace and then we're down a partid and there might be that many. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 19 Jan 2026 14:22:13 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }
lkml	[PATCH v3 00/47] arm_mpam: Add KVM/arm64 and resctrl glue code	This new version of the mpam missing pieces has no major rework from the previous version. It's mainly small corrections and code tidying based on review and things I spotted along the way. To be able to merge this we need review from more people and people to start testing on their platforms and giving some Tested-by tags. Change list in patches. As mentioned in the cover letter for v2, one major departure from the previous snapshot branches referenced in the base driver series is that the same MPAM setting are used for kernel-space and user-space. There are pros and cons of choosing this policy but I think it is the best thing to start with as there are AMD plans for adding a resctrl feature to allow a different closid/rmid configuration for user-space from kernel space. The AMD feature is called PLZA and is mentioned in this lpc slide deck[1]. This gives us a path forward to add support for having the EL1 and EL0 MPAM partid/pmg configuration differ from each other. >From James' cover letter: This is the missing piece to make MPAM usable resctrl in user-space. This has shed its debugfs code and the read/write 'event configuration' for the monitors to make the series smaller. This adds the arch code and KVM support first. I anticipate the whole thing going via arm64, but if goes via tip instead, the an immutable branch with those patches should be easy to do. Generally the resctrl glue code works by picking what MPAM features it can expose from the MPAM drive, then configuring the structs that back the resctrl helpers. If your platform is sufficiently Xeon shaped, you should be able to get L2/L3 CPOR bitmaps exposed via resctrl. CSU counters work if they are on/after the L3. MBWU counters are considerably more hairy, and depend on hueristics around the topology, and a bunch of stuff trying to emulate ABMC. If it didn't pick what you wanted it to, please share the debug messages produced when enabling dynamic debug and booting with: \| dyndbg="file mpam_resctrl.c +pl" I've not found a platform that can test all the behaviours around the monitors, so this is where I'd expect the most bugs. The MPAM spec that describes all the system and MMIO registers can be found here: https://developer.arm.com/documentation/ddi0598/db/?lang=en (Ignored the 'RETIRED' warning - that is just arm moving the documentation around. This document has the best overview) Based on v6.19-rc5 This series can be retrieved from: https://gitlab.arm.com/linux-arm/linux-bh.git mpam_resctrl_glue_v3 v2 can be found at: https://lore.kernel.org/linux-arm-kernel/20251219181147.3404071-1-ben.horgan@arm.com/ rfc can be found at: https://lore.kernel.org/linux-arm-kernel/20251205215901.17772-1-james.morse@arm.com/ [1] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf Ben Horgan (10): arm_mpam: Use non-atomic bitops when modifying feature bitmap arm64/sysreg: Add MPAMSM_EL1 register KVM: arm64: Preserve host MPAM configuration when changing traps KVM: arm64: Make MPAMSM_EL1 accesses UNDEF arm64: mpam: Initialise and context switch the MPAMSM_EL1 register KVM: arm64: Use kernel-space partid configuration for hypercalls arm_mpam: resctrl: Add rmid index helpers arm_mpam: resctrl: Add kunit test for rmid idx conversions arm_mpam: resctrl: Wait for cacheinfo to be ready arm_mpam: resctrl: Add kunit test for mbw min control generation Dave Martin (2): arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats arm_mpam: resctrl: Add kunit test for control format conversions James Morse (30): arm64: mpam: Context switch the MPAM registers arm64: mpam: Re-initialise MPAM regs when CPU comes online arm64: mpam: Advertise the CPUs MPAM limits to the driver arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values KVM: arm64: Force guest EL1 to use user-space's partid configuration arm_mpam: resctrl: Add boilerplate cpuhp and domain allocation arm_mpam: resctrl: Sort the order of the domain lists arm_mpam: resctrl: Pick the caches we will use as resctrl resources arm_mpam: resctrl: Implement resctrl_arch_reset_all_ctrls() arm_mpam: resctrl: Add resctrl_arch_get_config() arm_mpam: resctrl: Implement helpers to update configuration arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks arm_mpam: resctrl: Add CDP emulation arm_mpam: resctrl: Add support for 'MB' resource arm_mpam: resctrl: Add support for csu counters arm_mpam: resctrl: Pick classes for use as mbm counters arm_mpam: resctrl: Pre-allocate free running monitors arm_mpam: resctrl: Pre-allocate assignable monitors arm_mpam: resctrl: Add kunit test for ABMC/CDP interactions arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use arm_mpam: resctrl: Allow resctrl to allocate monitors arm_mpam: resctrl: Add resctrl_arch_rmid_read() and resctrl_arch_reset_rmid() arm_mpam: resctrl: Add resctrl_arch_cntr_read() & resctrl_arch_reset_cntr() arm_mpam: resctrl: Update the rmid reallocation limit arm_mpam: resctrl: Add empty definitions for assorted resctrl functions arm64: mpam: Select ARCH_HAS_CPU_RESCTRL arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl arm_mpam: Generate a configuration for min controls arm_mpam: Quirk CMN-650's CSU NRDY behaviour Jiapeng Chong (1): arm_mpam: Remove duplicate linux/srcu.h header Shanker Donthineni (4): arm_mpam: Add quirk framework arm_mpam: Add workaround for T241-MPAM-1 arm_mpam: Add workaround for T241-MPAM-4 arm_mpam: Add workaround for T241-MPAM-6 Documentation/arch/arm64/silicon-errata.rst \| 9 + arch/arm64/Kconfig \| 6 +- arch/arm64/include/asm/el2_setup.h \| 3 +- arch/arm64/include/asm/mpam.h \| 98 + arch/arm64/include/asm/resctrl.h \| 2 + arch/arm64/include/asm/thread_info.h \| 3 + arch/arm64/kernel/Makefile \| 1 + arch/arm64/kernel/cpufeature.c \| 21 +- arch/arm64/kernel/mpam.c \| 58 + arch/arm64/kernel/process.c \| 7 + arch/arm64/kvm/hyp/include/hyp/switch.h \| 12 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c \| 8 + arch/arm64/kvm/hyp/vhe/sysreg-sr.c \| 13 + arch/arm64/kvm/sys_regs.c \| 2 + arch/arm64/tools/sysreg \| 8 + drivers/resctrl/Kconfig \| 9 +- drivers/resctrl/Makefile \| 1 + drivers/resctrl/mpam_devices.c \| 306 ++- drivers/resctrl/mpam_internal.h \| 131 +- drivers/resctrl/mpam_resctrl.c \| 1930 +++++++++++++++++++ drivers/resctrl/test_mpam_devices.c \| 66 + drivers/resctrl/test_mpam_resctrl.c \| 426 ++++ include/linux/arm_mpam.h \| 32 + 23 files changed, 3119 insertions(+), 33 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/include/asm/resctrl.h create mode 100644 arch/arm64/kernel/mpam.c create mode 100644 drivers/resctrl/mpam_resctrl.c create mode 100644 drivers/resctrl/test_mpam_resctrl.c -- 2.43.0	Hi Gavin, On 1/19/26 06:37, Gavin Shan wrote: I've split out the part of PATCH[39/47] that removes the CONFIG_EXPERT restriction and put it before this patch. With that CONFIG_ARM64_MPAM will unconditionally select CONFIG_ARM64_MPAM_DRIVER. Thanks, Ben	{ "author": "Ben Horgan <ben.horgan@arm.com>", "date": "Mon, 19 Jan 2026 14:49:38 +0000", "thread_id": "20260112165914.4086692-1-ben.horgan@arm.com.mbox.gz" }

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