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large_stringclasses 2
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large_stringclasses 112
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large_stringclasses 112
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large_stringlengths 61
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lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
From: David Laight <david.laight.linux@gmail.com>
Compile-time tests being added to BIT() make it an 'integer constant
expression' rather than a pre-processor expression for W=1 builds.
This means BIT() can't be used in pre-processor conditional that
checks 'PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD'.
Change to use a normal 'if' statement, the compiler will optimise
away the unwanted code.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index d5ce20f47def..65dd5834d0cf 100644
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -4166,9 +4166,6 @@ static int ixgbevf_xmit_frame_ring(struct sk_buff *skb,
u32 tx_flags = 0;
u16 count = TXD_USE_COUNT(skb_headlen(skb));
struct ixgbevf_ipsec_tx_data ipsec_tx = { 0 };
-#if PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
- unsigned short f;
-#endif
u8 hdr_len = 0;
u8 *dst_mac = skb_header_pointer(skb, 0, 0, NULL);
@@ -4183,15 +4180,15 @@ static int ixgbevf_xmit_frame_ring(struct sk_buff *skb,
* + 1 desc for context descriptor,
* otherwise try next time
*/
-#if PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
- for (f = 0; f < skb_shinfo(skb)->nr_frags; f++) {
- skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
+ if (PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD) {
+ for (unsigned int f = 0; f < skb_shinfo(skb)->nr_frags; f++) {
+ skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
- count += TXD_USE_COUNT(skb_frag_size(frag));
+ count += TXD_USE_COUNT(skb_frag_size(frag));
+ }
+ } else {
+ count += skb_shinfo(skb)->nr_frags;
}
-#else
- count += skb_shinfo(skb)->nr_frags;
-#endif
if (ixgbevf_maybe_stop_tx(tx_ring, count + 3)) {
tx_ring->tx_stats.tx_busy++;
return NETDEV_TX_BUSY;
--
2.39.5
|
{
"author": "david.laight.linux@gmail.com",
"date": "Wed, 21 Jan 2026 14:57:22 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
From: David Laight <david.laight.linux@gmail.com>
The current checks in GENMASK/BIT (eg reversed high/low) only work
for 'integer constant expressions' not 'compile-time constants'.
This is true for const_true() and -Wshift-count-overflow/negative.
While compile-time constants may be unusual, they can happen through
function inlining.
This isn't too bad with gcc, but if clang detects a negative/over-large
shift it treats it as 'undefined behaviour' and silently discards all
code that would use the result, so:
int f(u32 x) {int n = 32; return x >> n; }
generates a function that just contains a 'return' instruction.
If 'n' was a variable that happened to be 32, most modern cpu mask
the count - so would return 'x', some might return 0.
Add extra checks for arguments that pass __builtin_constant_p()
but are not 'integer constant expressions.
__builtin_choose_expr() isn't strong enough to allow
_Static_assert() or ({ ... }) in the other branch so non-standard
schemes are used to report the errors.
To reduce pre-processor bloat the checks are only enabled for W=c
(implied by W=1) builds (where they are errors).
Update the unit tests to match.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
include/linux/bits.h | 45 +++++++++++++++++++++++++++++++++----------
lib/tests/test_bits.c | 34 +++++++++++++++++++-------------
2 files changed, 56 insertions(+), 23 deletions(-)
diff --git a/include/linux/bits.h b/include/linux/bits.h
index 43631a334314..0f559038981d 100644
--- a/include/linux/bits.h
+++ b/include/linux/bits.h
@@ -23,20 +23,35 @@
#include <linux/compiler.h>
#include <linux/overflow.h>
-#define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h)))
+#ifndef KBUILD_EXTRA_WARNc
+#define GENMASK_INPUT_CHECK(h, l, width) 0
+#else
+int GENMASK_INPUT_CHECK_FAIL(void) __compiletime_error("Invalid bit numbers");
+#define GENMASK_INPUT_CHECK(h, l, width) \
+ (__builtin_choose_expr(__is_constexpr((l) > (h)), \
+ sizeof(struct { char low_bit_greater_than_high[-((l) > (h))];}), \
+ __builtin_constant_p((l) | (h)) && \
+ ((l) < 0 || (l) > (h) || (h) >= width) && \
+ GENMASK_INPUT_CHECK_FAIL()))
+#endif
/*
- * Generate a mask for the specified type @t. Additional checks are made to
- * guarantee the value returned fits in that type, relying on
- * -Wshift-count-overflow compiler check to detect incompatible arguments.
+ * Generate a mask for the specified type @t.
+ * Checks are made to guarantee the value returned fits in that type.
+ * The compiler's -Wshift-count-overflow/negative check detects invalid values
+ * from 'constant integer expressions' but not other compile time constants.
+ * Clang treats out of value constants as 'undefined behaviour' and stops
+ * generating code - so explicit checks are needed.
+ * Neither BUILD_BUG() nor BUILD_BUG_ON_ZERO() can be used.
+ *
* For example, all these create build errors or warnings:
*
* - GENMASK(15, 20): wrong argument order
* - GENMASK(72, 15): doesn't fit unsigned long
* - GENMASK_U32(33, 15): doesn't fit in a u32
*/
-#define GENMASK_TYPE(t, h, l) \
- ((unsigned int)GENMASK_INPUT_CHECK(h, l) + \
+#define GENMASK_TYPE(t, h, l) \
+ ((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
((t)-1 << (l) & (t)-1 >> (BITS_PER_TYPE(t) - 1 - (h))))
#endif
@@ -52,16 +67,26 @@
#if !defined(__ASSEMBLY__)
/*
* Fixed-type variants of BIT(), with additional checks like GENMASK_TYPE().
- * The following examples generate compiler warnings from BIT_INPUT_CHECK().
+ * The following examples generate compiler errors from BIT_INPUT_CHECK().
*
* - BIT_U8(8)
* - BIT_U32(-1)
* - BIT_U32(40)
*/
-#define BIT_INPUT_CHECK(type, nr) \
- BUILD_BUG_ON_ZERO(const_true((nr) >= BITS_PER_TYPE(type)))
-#define BIT_TYPE(type, nr) ((unsigned int)BIT_INPUT_CHECK(type, nr) + ((type)1 << (nr)))
+#ifndef KBUILD_EXTRA_WARNc
+#define BIT_INPUT_CHECK(nr, width) 0
+#else
+int BIT_INPUT_CHECK_FAIL(void) __compiletime_error("Bit number out of range");
+#define BIT_INPUT_CHECK(nr, width) \
+ (__builtin_choose_expr(__is_constexpr(nr), \
+ sizeof(struct { char bit_number_too_big[-((nr) >= (width))];}), \
+ __builtin_constant_p(nr) && ((nr) < 0 || (nr) >= width) && \
+ BIT_INPUT_CHECK_FAIL()))
+#endif
+
+#define BIT_TYPE(type, nr) \
+ ((unsigned int)BIT_INPUT_CHECK(+(nr), BITS_PER_TYPE(type)) + ((type)1 << (nr)))
#endif /* defined(__ASSEMBLY__) */
#define BIT_U8(nr) BIT_TYPE(u8, nr)
diff --git a/lib/tests/test_bits.c b/lib/tests/test_bits.c
index 55be8230f9e7..36eb4661e78b 100644
--- a/lib/tests/test_bits.c
+++ b/lib/tests/test_bits.c
@@ -3,6 +3,8 @@
* Test cases for functions and macros in bits.h
*/
+#define KBUILD_EXTRA_WARNc 1
+
#include <kunit/test.h>
#include <linux/bits.h>
#include <linux/types.h>
@@ -118,24 +120,30 @@ static void genmask_u128_test(struct kunit *test)
static void genmask_input_check_test(struct kunit *test)
{
- unsigned int x, y;
- int z, w;
+ unsigned int x = 1, y = 2;
+ int z = 1, w = 2;
+
+ OPTIMIZER_HIDE_VAR(x);
+ OPTIMIZER_HIDE_VAR(y);
+ OPTIMIZER_HIDE_VAR(z);
+ OPTIMIZER_HIDE_VAR(w);
/* Unknown input */
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(x, 0));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(0, x));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(x, y));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(x, 0, 32));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(0, x, 32));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(x, y, 32));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(z, 0));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(0, z));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(z, w));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(z, 0, 32));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(0, z, 32));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(z, w, 32));
/* Valid input */
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(1, 1));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(39, 21));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(100, 80));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(110, 65));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(127, 0));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(1, 1, 32));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(39, 21, 64));
+
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(100, 80, 128));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(110, 65, 128));
+ KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(127, 0, 128));
}
--
2.39.5
|
{
"author": "david.laight.linux@gmail.com",
"date": "Wed, 21 Jan 2026 14:57:28 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
From: David Laight <david.laight.linux@gmail.com>
Since all the GENMASK() values are compile-time constants they can
be tested with BUILD_BUG_ON() rather than KUNIT_EXPECT_EQ().
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
lib/tests/test_bits.c | 90 +++++++++++++++++++++----------------------
1 file changed, 45 insertions(+), 45 deletions(-)
diff --git a/lib/tests/test_bits.c b/lib/tests/test_bits.c
index 36eb4661e78b..4d3a895f490c 100644
--- a/lib/tests/test_bits.c
+++ b/lib/tests/test_bits.c
@@ -32,30 +32,30 @@ static_assert(assert_type(u64, GENMASK_U64(63, 0)) == U64_MAX);
static void __genmask_test(struct kunit *test)
{
- KUNIT_EXPECT_EQ(test, 1ul, __GENMASK(0, 0));
- KUNIT_EXPECT_EQ(test, 3ul, __GENMASK(1, 0));
- KUNIT_EXPECT_EQ(test, 6ul, __GENMASK(2, 1));
- KUNIT_EXPECT_EQ(test, 0xFFFFFFFFul, __GENMASK(31, 0));
+ BUILD_BUG_ON(__GENMASK(0, 0) != 1ul);
+ BUILD_BUG_ON(__GENMASK(1, 0) != 3ul);
+ BUILD_BUG_ON(__GENMASK(2, 1) != 6ul);
+ BUILD_BUG_ON(__GENMASK(31, 0) != 0xFFFFFFFFul);
}
static void __genmask_ull_test(struct kunit *test)
{
- KUNIT_EXPECT_EQ(test, 1ull, __GENMASK_ULL(0, 0));
- KUNIT_EXPECT_EQ(test, 3ull, __GENMASK_ULL(1, 0));
- KUNIT_EXPECT_EQ(test, 0x000000ffffe00000ull, __GENMASK_ULL(39, 21));
- KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, __GENMASK_ULL(63, 0));
+ BUILD_BUG_ON(__GENMASK_ULL(0, 0) != 1ull);
+ BUILD_BUG_ON(__GENMASK_ULL(1, 0) != 3ull);
+ BUILD_BUG_ON(__GENMASK_ULL(39, 21) != 0x000000ffffe00000ull);
+ BUILD_BUG_ON(__GENMASK_ULL(63, 0) != 0xffffffffffffffffull);
}
static void genmask_test(struct kunit *test)
{
- KUNIT_EXPECT_EQ(test, 1ul, GENMASK(0, 0));
- KUNIT_EXPECT_EQ(test, 3ul, GENMASK(1, 0));
- KUNIT_EXPECT_EQ(test, 6ul, GENMASK(2, 1));
- KUNIT_EXPECT_EQ(test, 0xFFFFFFFFul, GENMASK(31, 0));
+ BUILD_BUG_ON(GENMASK(0, 0) != 1ul);
+ BUILD_BUG_ON(GENMASK(1, 0) != 3ul);
+ BUILD_BUG_ON(GENMASK(2, 1) != 6ul);
+ BUILD_BUG_ON(GENMASK(31, 0) != 0xFFFFFFFFul);
- KUNIT_EXPECT_EQ(test, 1u, GENMASK_U8(0, 0));
- KUNIT_EXPECT_EQ(test, 3u, GENMASK_U16(1, 0));
- KUNIT_EXPECT_EQ(test, 0x10000, GENMASK_U32(16, 16));
+ BUILD_BUG_ON(GENMASK_U8(0, 0) != 1u);
+ BUILD_BUG_ON(GENMASK_U16(1, 0) != 3u);
+ BUILD_BUG_ON(GENMASK_U32(16, 16) != 0x10000);
#ifdef TEST_GENMASK_FAILURES
/* these should fail compilation */
@@ -75,10 +75,10 @@ static void genmask_test(struct kunit *test)
static void genmask_ull_test(struct kunit *test)
{
- KUNIT_EXPECT_EQ(test, 1ull, GENMASK_ULL(0, 0));
- KUNIT_EXPECT_EQ(test, 3ull, GENMASK_ULL(1, 0));
- KUNIT_EXPECT_EQ(test, 0x000000ffffe00000ull, GENMASK_ULL(39, 21));
- KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, GENMASK_ULL(63, 0));
+ BUILD_BUG_ON(GENMASK_ULL(0, 0) != 1ull);
+ BUILD_BUG_ON(GENMASK_ULL(1, 0) != 3ull);
+ BUILD_BUG_ON(GENMASK_ULL(39, 21) != 0x000000ffffe00000ull);
+ BUILD_BUG_ON(GENMASK_ULL(63, 0) != 0xffffffffffffffffull);
#ifdef TEST_GENMASK_FAILURES
/* these should fail compilation */
@@ -92,23 +92,23 @@ static void genmask_u128_test(struct kunit *test)
{
#ifdef CONFIG_ARCH_SUPPORTS_INT128
/* Below 64 bit masks */
- KUNIT_EXPECT_EQ(test, 0x0000000000000001ull, GENMASK_U128(0, 0));
- KUNIT_EXPECT_EQ(test, 0x0000000000000003ull, GENMASK_U128(1, 0));
- KUNIT_EXPECT_EQ(test, 0x0000000000000006ull, GENMASK_U128(2, 1));
- KUNIT_EXPECT_EQ(test, 0x00000000ffffffffull, GENMASK_U128(31, 0));
- KUNIT_EXPECT_EQ(test, 0x000000ffffe00000ull, GENMASK_U128(39, 21));
- KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, GENMASK_U128(63, 0));
+ BUILD_BUG_ON(GENMASK_U128(0, 0) != 0x0000000000000001ull);
+ BUILD_BUG_ON(GENMASK_U128(1, 0) != 0x0000000000000003ull);
+ BUILD_BUG_ON(GENMASK_U128(2, 1) != 0x0000000000000006ull);
+ BUILD_BUG_ON(GENMASK_U128(31, 0) != 0x00000000ffffffffull);
+ BUILD_BUG_ON(GENMASK_U128(39, 21) != 0x000000ffffe00000ull);
+ BUILD_BUG_ON(GENMASK_U128(63, 0) != 0xffffffffffffffffull);
/* Above 64 bit masks - only 64 bit portion can be validated once */
- KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, GENMASK_U128(64, 0) >> 1);
- KUNIT_EXPECT_EQ(test, 0x00000000ffffffffull, GENMASK_U128(81, 50) >> 50);
- KUNIT_EXPECT_EQ(test, 0x0000000000ffffffull, GENMASK_U128(87, 64) >> 64);
- KUNIT_EXPECT_EQ(test, 0x0000000000ff0000ull, GENMASK_U128(87, 80) >> 64);
-
- KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, GENMASK_U128(127, 0) >> 64);
- KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, (u64)GENMASK_U128(127, 0));
- KUNIT_EXPECT_EQ(test, 0x0000000000000003ull, GENMASK_U128(127, 126) >> 126);
- KUNIT_EXPECT_EQ(test, 0x0000000000000001ull, GENMASK_U128(127, 127) >> 127);
+ BUILD_BUG_ON(GENMASK_U128(64, 0) >> 1 != 0xffffffffffffffffull);
+ BUILD_BUG_ON(GENMASK_U128(81, 50) >> 50 != 0x00000000ffffffffull);
+ BUILD_BUG_ON(GENMASK_U128(87, 64) >> 64 != 0x0000000000ffffffull);
+ BUILD_BUG_ON(GENMASK_U128(87, 80) >> 64 != 0x0000000000ff0000ull);
+
+ BUILD_BUG_ON(GENMASK_U128(127, 0) >> 64 != 0xffffffffffffffffull);
+ BUILD_BUG_ON((u64)GENMASK_U128(127, 0) != 0xffffffffffffffffull);
+ BUILD_BUG_ON(GENMASK_U128(127, 126) >> 126 != 0x0000000000000003ull);
+ BUILD_BUG_ON(GENMASK_U128(127, 127) >> 127 != 0x0000000000000001ull);
#ifdef TEST_GENMASK_FAILURES
/* these should fail compilation */
GENMASK_U128(0, 1);
@@ -129,21 +129,21 @@ static void genmask_input_check_test(struct kunit *test)
OPTIMIZER_HIDE_VAR(w);
/* Unknown input */
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(x, 0, 32));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(0, x, 32));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(x, y, 32));
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(x, 0, 32) != 0);
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(0, x, 32) != 0);
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(x, y, 32) != 0);
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(z, 0, 32));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(0, z, 32));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(z, w, 32));
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(z, 0, 32) != 0);
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(0, z, 32) != 0);
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(z, w, 32) != 0);
/* Valid input */
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(1, 1, 32));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(39, 21, 64));
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(1, 1, 32) != 0);
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(39, 21, 64) != 0);
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(100, 80, 128));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(110, 65, 128));
- KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(127, 0, 128));
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(100, 80, 128) != 0);
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(110, 65, 128) != 0);
+ BUILD_BUG_ON(GENMASK_INPUT_CHECK(127, 0, 128) != 0);
}
--
2.39.5
|
{
"author": "david.laight.linux@gmail.com",
"date": "Wed, 21 Jan 2026 14:57:30 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
From: David Laight <david.laight.linux@gmail.com>
The definition of BIT() was moved from linux/bits.h to vdso/bits.h to
isolate the vdso from 'normal' kernel headers.
BIT_ULL() was then moved to be defined in the same place for consistency.
Since then linux/bits.h had gained BIT_Unn() and it really makes sense
for BIT() and BIT_ULL() to be defined in the same place.
Move BIT_ULL() and make code that include both headers use the definition
of BIT() from linux/bits.h
Add BIT_U128() for completness.
This lets BIT() pick up the extra compile time checks for W=[1c] builds
that detect errors like:
long foo(void) { int x = 64; return BIT(x); }
For which clang (silently) just generates a 'return' instruction.
Note that nothing the the x86-64 build relies on the definition in
vdso/bits.h, linux/bits.h is always included.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
include/linux/bits.h | 7 ++++++-
include/vdso/bits.h | 2 +-
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/include/linux/bits.h b/include/linux/bits.h
index 0f559038981d..3dd32b9eef35 100644
--- a/include/linux/bits.h
+++ b/include/linux/bits.h
@@ -2,7 +2,6 @@
#ifndef __LINUX_BITS_H
#define __LINUX_BITS_H
-#include <vdso/bits.h>
#include <uapi/linux/bits.h>
#define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG))
@@ -89,10 +88,16 @@ int BIT_INPUT_CHECK_FAIL(void) __compiletime_error("Bit number out of range");
((unsigned int)BIT_INPUT_CHECK(+(nr), BITS_PER_TYPE(type)) + ((type)1 << (nr)))
#endif /* defined(__ASSEMBLY__) */
+/* Prefer this definition of BIT() to the one in vdso/bits.h */
+#undef BIT
+#define __VDSO_BITS_H
+#define BIT(nr) BIT_TYPE(unsigned long, nr)
+#define BIT_ULL(nr) BIT_TYPE(unsigned long long, nr)
#define BIT_U8(nr) BIT_TYPE(u8, nr)
#define BIT_U16(nr) BIT_TYPE(u16, nr)
#define BIT_U32(nr) BIT_TYPE(u32, nr)
#define BIT_U64(nr) BIT_TYPE(u64, nr)
+#define BIT_U128(nr) BIT_TYPE(u128, nr)
#if defined(__ASSEMBLY__)
diff --git a/include/vdso/bits.h b/include/vdso/bits.h
index 388b212088ea..a6ac1e6b637c 100644
--- a/include/vdso/bits.h
+++ b/include/vdso/bits.h
@@ -4,7 +4,7 @@
#include <vdso/const.h>
+/* Most code picks up BIT() from linux/bits.h */
#define BIT(nr) (UL(1) << (nr))
-#define BIT_ULL(nr) (ULL(1) << (nr))
#endif /* __VDSO_BITS_H */
--
2.39.5
|
{
"author": "david.laight.linux@gmail.com",
"date": "Wed, 21 Jan 2026 14:57:29 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Wed, Jan 21, 2026 at 02:57:29PM +0000, david.laight.linux@gmail.com wrote:
This is ugly.
Why can't the vDSO code make use of those checks, too?
Or use _BITUL() from the UAPI in the vDSO and remove vdso/bits.h.
|
{
"author": "Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <thomas.weissschuh@linutronix.de>",
"date": "Wed, 21 Jan 2026 16:17:18 +0100",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On 21/01/2026 at 15:57, david.laight.linux@gmail.com wrote:
Did those new checks actually found any real problem in the code? This
adds a lot of complexity so I am not sure whether this is a winning
trade-off.
But then, you only solve that shift problem for GENMASK() and
BIT(). Any other usage of the left/right shifts are not diagnosed
unless your check get copy pasted all over the place.
I think that such a check belongs to a static analyzer. Speaking of
which:
$ cat test.c
typedef unsigned int u32;
static int f(u32 x) {int n = 32; return x >> n; }
$ sparse test.c
test.c:2:46: warning: shift too big (32) for type unsigned int$ cat test.c
So here, I would rather keep relying on sparse rather that introducing
the W=c logic and all that macro complexity.
Yours sincerely,
Vincent Mailhol
|
{
"author": "Vincent Mailhol <mailhol@kernel.org>",
"date": "Wed, 21 Jan 2026 19:43:07 +0100",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Wed, 21 Jan 2026 19:43:07 +0100
Vincent Mailhol <mailhol@kernel.org> wrote:
Not in an x86-64 allmodconfig build.
They might in a 32bit one where there have definitely been issues.
I suspect the compiler test will find more than sparse.
I liked getting that to work, but maybe it is OTT.
But the W=c is more generally useful.
As well as removing all the compile-time tests from GENMASK() and
(in another patch FIELD_PREP()) which really do bloat the .i file,
I'd like to add some new tests to min/max/clamp to try to get rid
of the more dodgy (and likely buggy) cases without breaking
everyone's build - just failing the W=1 builds is better.
Using a separate flag means you can use W=ce to stop the build,
doing a W=1e build is hopeless.
David
|
{
"author": "David Laight <david.laight.linux@gmail.com>",
"date": "Wed, 21 Jan 2026 19:14:48 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Wed, 21 Jan 2026 16:17:18 +0100
Thomas Weißschuh <thomas.weissschuh@linutronix.de> wrote:
It works :-)
I could have put an #ifndef BIT in vdso/bits.h instead.
I didn't actually find anything that just needed vdso/bits.h
linux/bits.h would get included - eg (IIRC) because of warn_on_once().
I'm not that sure why it got separated, it isn't as though it defines
anything that is code version specific.
David
|
{
"author": "David Laight <david.laight.linux@gmail.com>",
"date": "Wed, 21 Jan 2026 19:24:51 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Wed, Jan 21, 2026 at 02:57:18PM +0000, david.laight.linux@gmail.com wrote:
Sure!
Reviewed-by: Kees Cook <kees@kernel.org>
--
Kees Cook
|
{
"author": "Kees Cook <kees@kernel.org>",
"date": "Wed, 21 Jan 2026 12:59:36 -0800",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on next-20260120]
url: https://github.com/intel-lab-lkp/linux/commits/david-laight-linux-gmail-com/overflow-Reduce-expansion-of-__type_max/20260122-013456
base: next-20260120
patch link: https://lore.kernel.org/r/20260121145731.3623-13-david.laight.linux%40gmail.com
patch subject: [PATCH next 12/14] bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
config: arm-allnoconfig (https://download.01.org/0day-ci/archive/20260122/202601220832.NJbHlnXC-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260122/202601220832.NJbHlnXC-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601220832.NJbHlnXC-lkp@intel.com/
All errors (new ones prefixed by >>):
163 | _SIG_SET_BINOP(sigandnsets, _sig_andn)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:139:8: note: expanded from macro '_SIG_SET_BINOP'
139 | b3 = b->sig[3]; b2 = b->sig[2]; \
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:14:
In file included from include/linux/mm.h:36:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:163:1: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
163 | _SIG_SET_BINOP(sigandnsets, _sig_andn)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:139:24: note: expanded from macro '_SIG_SET_BINOP'
139 | b3 = b->sig[3]; b2 = b->sig[2]; \
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:14:
In file included from include/linux/mm.h:36:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:163:1: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
163 | _SIG_SET_BINOP(sigandnsets, _sig_andn)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:140:3: note: expanded from macro '_SIG_SET_BINOP'
140 | r->sig[3] = op(a3, b3); \
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:14:
In file included from include/linux/mm.h:36:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:163:1: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
163 | _SIG_SET_BINOP(sigandnsets, _sig_andn)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:141:3: note: expanded from macro '_SIG_SET_BINOP'
141 | r->sig[2] = op(a2, b2); \
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:14:
In file included from include/linux/mm.h:36:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:187:1: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
187 | _SIG_SET_OP(signotset, _sig_not)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:174:27: note: expanded from macro '_SIG_SET_OP'
174 | case 4: set->sig[3] = op(set->sig[3]); \
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:14:
In file included from include/linux/mm.h:36:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:187:1: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
187 | _SIG_SET_OP(signotset, _sig_not)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:174:10: note: expanded from macro '_SIG_SET_OP'
174 | case 4: set->sig[3] = op(set->sig[3]); \
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:14:
In file included from include/linux/mm.h:36:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:187:1: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
187 | _SIG_SET_OP(signotset, _sig_not)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:175:20: note: expanded from macro '_SIG_SET_OP'
175 | set->sig[2] = op(set->sig[2]); \
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:14:
In file included from include/linux/mm.h:36:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:187:1: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
187 | _SIG_SET_OP(signotset, _sig_not)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:175:3: note: expanded from macro '_SIG_SET_OP'
175 | set->sig[2] = op(set->sig[2]); \
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:14:
994 | const vm_flags_t mask = BIT((__force int)bit);
| ^
include/linux/bits.h:94:18: note: expanded from macro 'BIT'
94 | #define BIT(nr) BIT_TYPE(unsigned long, nr)
| ^
include/linux/bits.h:88:17: note: expanded from macro 'BIT_TYPE'
88 | ((unsigned int)BIT_INPUT_CHECK(+(nr), BITS_PER_TYPE(type)) + ((type)1 << (nr)))
| ^
include/linux/bits.h:82:24: note: expanded from macro 'BIT_INPUT_CHECK'
82 | sizeof(struct { char bit_number_too_big[-((nr) >= (width))];}), \
| ^
28 warnings and 16 errors generated.
make[3]: *** [scripts/Makefile.build:182: arch/arm/kernel/asm-offsets.s] Error 1
make[3]: Target 'prepare' not remade because of errors.
make[2]: *** [Makefile:1330: prepare0] Error 2
make[2]: Target 'prepare' not remade because of errors.
make[1]: *** [Makefile:248: __sub-make] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:248: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
vim +994 include/linux/mm.h
bc292ab00f6c7a6 Suren Baghdasaryan 2023-01-26 990
568822502383acd Lorenzo Stoakes 2025-11-18 991 static inline bool __vma_flag_atomic_valid(struct vm_area_struct *vma,
2b6a3f061f11372 Lorenzo Stoakes 2025-11-25 992 vma_flag_t bit)
568822502383acd Lorenzo Stoakes 2025-11-18 993 {
2b6a3f061f11372 Lorenzo Stoakes 2025-11-25 @994 const vm_flags_t mask = BIT((__force int)bit);
568822502383acd Lorenzo Stoakes 2025-11-18 995
568822502383acd Lorenzo Stoakes 2025-11-18 996 /* Only specific flags are permitted */
568822502383acd Lorenzo Stoakes 2025-11-18 997 if (WARN_ON_ONCE(!(mask & VM_ATOMIC_SET_ALLOWED)))
568822502383acd Lorenzo Stoakes 2025-11-18 998 return false;
568822502383acd Lorenzo Stoakes 2025-11-18 999
568822502383acd Lorenzo Stoakes 2025-11-18 1000 return true;
568822502383acd Lorenzo Stoakes 2025-11-18 1001 }
568822502383acd Lorenzo Stoakes 2025-11-18 1002
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
|
{
"author": "kernel test robot <lkp@intel.com>",
"date": "Thu, 22 Jan 2026 08:50:22 +0800",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on next-20260120]
url: https://github.com/intel-lab-lkp/linux/commits/david-laight-linux-gmail-com/overflow-Reduce-expansion-of-__type_max/20260122-013456
base: next-20260120
patch link: https://lore.kernel.org/r/20260121145731.3623-12-david.laight.linux%40gmail.com
patch subject: [PATCH next 11/14] bit: Strengthen compile-time tests in GENMASK() and BIT()
config: s390-randconfig-001-20260122 (https://download.01.org/0day-ci/archive/20260122/202601220829.MgTMeqqN-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260122/202601220829.MgTMeqqN-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601220829.MgTMeqqN-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from arch/s390/include/asm/bug.h:60,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from arch/s390/include/asm/cmpxchg.h:11,
from arch/s390/include/asm/atomic.h:16,
from include/linux/atomic.h:7,
from include/asm-generic/bitops/atomic.h:5,
from arch/s390/include/asm/bitops.h:75,
from include/linux/bitops.h:67,
from include/linux/kernel.h:23,
from net/core/page_pool.c:10:
In function 'netmem_clear_pp_magic',
inlined from 'page_pool_clear_pp_info' at net/core/page_pool.c:721:2:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/asm-generic/bug.h:120:25: note: in definition of macro 'WARN_ON_ONCE'
int __ret_warn_on = !!(condition); \
^~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
net/core/netmem_priv.h:18:52: note: in expansion of macro 'PP_DMA_INDEX_MASK'
WARN_ON_ONCE(netmem_to_nmdesc(netmem)->pp_magic & PP_DMA_INDEX_MASK);
^~~~~~~~~~~~~~~~~
--
In file included from include/linux/bitops.h:6,
from arch/s390/include/asm/machine.h:25,
from arch/s390/include/asm/lowcore.h:13,
from arch/s390/include/asm/current.h:13,
from arch/s390/include/asm/preempt.h:5,
from include/linux/preempt.h:79,
from arch/s390/include/asm/timex.h:13,
from include/linux/timex.h:67,
from include/linux/time32.h:13,
from include/linux/time.h:60,
from include/linux/stat.h:19,
from include/linux/module.h:13,
from net/core/skbuff.c:37:
In function 'netmem_get_pp_magic',
inlined from 'netmem_is_pp' at net/core/netmem_priv.h:25:10,
inlined from 'napi_pp_put_page' at net/core/skbuff.c:1027:6:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
net/core/netmem_priv.h:8:47: note: in expansion of macro 'PP_DMA_INDEX_MASK'
return netmem_to_nmdesc(netmem)->pp_magic & ~PP_DMA_INDEX_MASK;
^~~~~~~~~~~~~~~~~
In function 'netmem_is_pp',
inlined from 'napi_pp_put_page' at net/core/skbuff.c:1027:6:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
include/linux/mm.h:4650:25: note: in expansion of macro 'PP_DMA_INDEX_MASK'
#define PP_MAGIC_MASK ~(PP_DMA_INDEX_MASK | 0x3UL)
^~~~~~~~~~~~~~~~~
net/core/netmem_priv.h:25:40: note: in expansion of macro 'PP_MAGIC_MASK'
return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE;
^~~~~~~~~~~~~
In function 'netmem_get_pp_magic',
inlined from 'netmem_is_pp' at net/core/netmem_priv.h:25:10,
inlined from 'napi_pp_put_page' at net/core/skbuff.c:1027:6:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
net/core/netmem_priv.h:8:47: note: in expansion of macro 'PP_DMA_INDEX_MASK'
return netmem_to_nmdesc(netmem)->pp_magic & ~PP_DMA_INDEX_MASK;
^~~~~~~~~~~~~~~~~
In function 'netmem_is_pp',
inlined from 'napi_pp_put_page' at net/core/skbuff.c:1027:6:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
include/linux/mm.h:4650:25: note: in expansion of macro 'PP_DMA_INDEX_MASK'
#define PP_MAGIC_MASK ~(PP_DMA_INDEX_MASK | 0x3UL)
^~~~~~~~~~~~~~~~~
net/core/netmem_priv.h:25:40: note: in expansion of macro 'PP_MAGIC_MASK'
return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE;
^~~~~~~~~~~~~
In function 'netmem_get_pp_magic',
inlined from 'netmem_is_pp' at net/core/netmem_priv.h:25:10,
inlined from 'skb_pp_frag_ref' at net/core/skbuff.c:1067:7,
inlined from 'skb_try_coalesce' at net/core/skbuff.c:6203:6:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
net/core/netmem_priv.h:8:47: note: in expansion of macro 'PP_DMA_INDEX_MASK'
return netmem_to_nmdesc(netmem)->pp_magic & ~PP_DMA_INDEX_MASK;
^~~~~~~~~~~~~~~~~
In function 'netmem_is_pp',
inlined from 'skb_pp_frag_ref' at net/core/skbuff.c:1067:7,
inlined from 'skb_try_coalesce' at net/core/skbuff.c:6203:6:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
include/linux/mm.h:4650:25: note: in expansion of macro 'PP_DMA_INDEX_MASK'
#define PP_MAGIC_MASK ~(PP_DMA_INDEX_MASK | 0x3UL)
^~~~~~~~~~~~~~~~~
net/core/netmem_priv.h:25:40: note: in expansion of macro 'PP_MAGIC_MASK'
return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE;
^~~~~~~~~~~~~
In function 'netmem_get_pp_magic',
inlined from 'netmem_is_pp' at net/core/netmem_priv.h:25:10,
inlined from 'skb_pp_frag_ref' at net/core/skbuff.c:1067:7,
inlined from 'skb_try_coalesce' at net/core/skbuff.c:6203:6:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
net/core/netmem_priv.h:8:47: note: in expansion of macro 'PP_DMA_INDEX_MASK'
return netmem_to_nmdesc(netmem)->pp_magic & ~PP_DMA_INDEX_MASK;
^~~~~~~~~~~~~~~~~
In function 'netmem_is_pp',
inlined from 'skb_pp_frag_ref' at net/core/skbuff.c:1067:7,
inlined from 'skb_try_coalesce' at net/core/skbuff.c:6203:6:
GENMASK_INPUT_CHECK_FAIL()))
^~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:54:17: note: in expansion of macro 'GENMASK_INPUT_CHECK'
((unsigned int)GENMASK_INPUT_CHECK(h, l, BITS_PER_TYPE(t)) + \
^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:58:24: note: in expansion of macro 'GENMASK_TYPE'
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
^~~~~~~~~~~~
include/linux/mm.h:4641:27: note: in expansion of macro 'GENMASK'
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
^~~~~~~
include/linux/mm.h:4650:25: note: in expansion of macro 'PP_DMA_INDEX_MASK'
#define PP_MAGIC_MASK ~(PP_DMA_INDEX_MASK | 0x3UL)
^~~~~~~~~~~~~~~~~
net/core/netmem_priv.h:25:40: note: in expansion of macro 'PP_MAGIC_MASK'
return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE;
^~~~~~~~~~~~~
vim +/GENMASK_INPUT_CHECK_FAIL +35 include/linux/bits.h
25
26 #ifndef KBUILD_EXTRA_WARNc
27 #define GENMASK_INPUT_CHECK(h, l, width) 0
28 #else
29 int GENMASK_INPUT_CHECK_FAIL(void) __compiletime_error("Invalid bit numbers");
30 #define GENMASK_INPUT_CHECK(h, l, width) \
31 (__builtin_choose_expr(__is_constexpr((l) > (h)), \
32 sizeof(struct { char low_bit_greater_than_high[-((l) > (h))];}), \
33 __builtin_constant_p((l) | (h)) && \
34 ((l) < 0 || (l) > (h) || (h) >= width) && \
> 35 GENMASK_INPUT_CHECK_FAIL()))
36 #endif
37
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
|
{
"author": "kernel test robot <lkp@intel.com>",
"date": "Thu, 22 Jan 2026 09:11:53 +0800",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on next-20260120]
url: https://github.com/intel-lab-lkp/linux/commits/david-laight-linux-gmail-com/overflow-Reduce-expansion-of-__type_max/20260122-013456
base: next-20260120
patch link: https://lore.kernel.org/r/20260121145731.3623-13-david.laight.linux%40gmail.com
patch subject: [PATCH next 12/14] bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
config: arm64-allmodconfig (https://download.01.org/0day-ci/archive/20260122/202601220951.7C4YG7hB-lkp@intel.com/config)
compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project cd708029e0b2869e80abe31ddb175f7c35361f90)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260122/202601220951.7C4YG7hB-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601220951.7C4YG7hB-lkp@intel.com/
All error/warnings (new ones prefixed by >>):
In file included from kernel/bounds.c:14:
In file included from include/linux/log2.h:12:
In file included from include/linux/bitops.h:28:
In file included from include/asm-generic/bitops/generic-non-atomic.h:7:
In file included from arch/arm64/include/asm/barrier.h:14:
18 | #if ARM64_NCAPS >= ARM64_CB_BIT
| ^
arch/arm64/include/asm/alternative-macros.h:16:22: note: expanded from macro 'ARM64_CB_BIT'
16 | #define ARM64_CB_BIT BIT(ARM64_CB_SHIFT)
| ^
include/linux/bits.h:94:18: note: expanded from macro 'BIT'
94 | #define BIT(nr) BIT_TYPE(unsigned long, nr)
| ^
include/linux/bits.h:88:4: note: expanded from macro 'BIT_TYPE'
88 | ((unsigned int)BIT_INPUT_CHECK(+(nr), BITS_PER_TYPE(type)) + ((type)1 << (nr)))
| ^
In file included from kernel/bounds.c:14:
In file included from include/linux/log2.h:12:
In file included from include/linux/bitops.h:28:
In file included from include/asm-generic/bitops/generic-non-atomic.h:7:
In file included from arch/arm64/include/asm/barrier.h:14:
18 | #if ARM64_NCAPS >= ARM64_CB_BIT
| ^~~~~~~~~~~~
arch/arm64/include/asm/alternative-macros.h:16:22: note: expanded from macro 'ARM64_CB_BIT'
16 | #define ARM64_CB_BIT BIT(ARM64_CB_SHIFT)
| ^~~~~~~~~~~~~~~~~~~
include/linux/bits.h:94:18: note: expanded from macro 'BIT'
94 | #define BIT(nr) BIT_TYPE(unsigned long, nr)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/bits.h:88:13: note: expanded from macro 'BIT_TYPE'
88 | ((unsigned int)BIT_INPUT_CHECK(+(nr), BITS_PER_TYPE(type)) + ((type)1 << (nr)))
| ~~~~~~~~ ^
1 warning and 1 error generated.
make[3]: *** [scripts/Makefile.build:182: kernel/bounds.s] Error 1
make[3]: Target 'prepare' not remade because of errors.
make[2]: *** [Makefile:1330: prepare0] Error 2
make[2]: Target 'prepare' not remade because of errors.
make[1]: *** [Makefile:248: __sub-make] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:248: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
vim +18 arch/arm64/include/asm/alternative-macros.h
4c0bd995d73ed8 Mark Rutland 2022-09-12 17
4c0bd995d73ed8 Mark Rutland 2022-09-12 @18 #if ARM64_NCAPS >= ARM64_CB_BIT
4c0bd995d73ed8 Mark Rutland 2022-09-12 19 #error "cpucaps have overflown ARM64_CB_BIT"
4c0bd995d73ed8 Mark Rutland 2022-09-12 20 #endif
7cda23da52ad79 Will Deacon 2020-06-30 21
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
|
{
"author": "kernel test robot <lkp@intel.com>",
"date": "Thu, 22 Jan 2026 09:23:16 +0800",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
Hi,
kernel test robot noticed the following build warnings:
[auto build test WARNING on next-20260120]
url: https://github.com/intel-lab-lkp/linux/commits/david-laight-linux-gmail-com/overflow-Reduce-expansion-of-__type_max/20260122-013456
base: next-20260120
patch link: https://lore.kernel.org/r/20260121145731.3623-12-david.laight.linux%40gmail.com
patch subject: [PATCH next 11/14] bit: Strengthen compile-time tests in GENMASK() and BIT()
config: mips-randconfig-r132-20260122 (https://download.01.org/0day-ci/archive/20260122/202601221237.soiAkwkN-lkp@intel.com/config)
compiler: mips64-linux-gcc (GCC) 10.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260122/202601221237.soiAkwkN-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601221237.soiAkwkN-lkp@intel.com/
sparse warnings: (new ones prefixed by >>)
kernel/kthread.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
--
kernel/reboot.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
--
lib/idr.c: note: in included file (through include/linux/bitmap.h):
include/linux/find.h:188:32: sparse: sparse: Variable length array is used.
include/linux/find.h:388:46: sparse: sparse: Variable length array is used.
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
lib/xarray.c: note: in included file (through include/linux/bitmap.h):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
lib/xarray.c: note: in included file:
lib/xarray.c: note: in included file (through include/linux/bitmap.h):
--
lib/find_bit.c: note: in included file (through include/linux/bitmap.h):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
include/linux/find.h:238:46: sparse: sparse: Variable length array is used.
--
lib/bitmap-str.c: note: in included file:
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
lib/bitmap-str.c: note: in included file (through include/linux/bitmap.h):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
lib/genalloc.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
mm/oom_kill.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
--
mm/vmscan.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
--
mm/shmem.c: note: in included file (through include/linux/cpumask.h, include/linux/smp.h, arch/mips/include/asm/cpu-type.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
--
mm/percpu.c: note: in included file (through include/linux/bitmap.h):
include/linux/find.h:409:45: sparse: sparse: Variable length array is used.
include/linux/find.h:188:32: sparse: sparse: Variable length array is used.
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
mm/percpu.c: note: in included file:
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
--
mm/vmalloc.c: note: in included file (through arch/mips/include/asm/page.h, include/linux/shm.h, include/linux/sched.h, ...):
include/asm-generic/memory_model.h:30:23: sparse: sparse: unsigned value that used to be signed checked against zero?
mm/vmalloc.c:554:21: sparse: signed value source
mm/vmalloc.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
mm/vmalloc.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
mm/vmalloc.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:188:32: sparse: sparse: Variable length array is used.
--
mm/slub.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
--
mm/hugetlb.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
mm/huge_memory.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
--
arch/mips/kernel/cmpxchg.c:61:16: sparse: sparse: Variable length array is used.
--
arch/mips/kernel/cpu-probe.c:712:45: sparse: sparse: Variable length array is used.
arch/mips/kernel/cpu-probe.c:214:9: sparse: sparse: cast truncates bits from constant value (3fffffffffffe000 becomes ffffe000)
arch/mips/kernel/cpu-probe.c:214:9: sparse: sparse: cast truncates bits from constant value (3fffffffffffe000 becomes ffffe000)
--
--
net/ethtool/ioctl.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, include/linux/smp.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
net/ethtool/bitset.c: note: in included file (through include/linux/ethtool.h, include/uapi/linux/ethtool_netlink.h, include/linux/ethtool_netlink.h):
--
net/ethtool/linkmodes.c: note: in included file (through include/linux/bitmap.h, include/linux/ethtool.h, include/uapi/linux/ethtool_netlink.h, ...):
--
net/ethtool/fec.c: note: in included file (through include/linux/bitmap.h, include/linux/ethtool.h, include/uapi/linux/ethtool_netlink.h, ...):
--
drivers/clk/clk-multiplier.c:141:17: sparse: sparse: Variable length array is used.
--
drivers/clk/clk-fractional-divider.c:90:17: sparse: sparse: Variable length array is used.
drivers/clk/clk-fractional-divider.c:146:25: sparse: sparse: Variable length array is used.
drivers/clk/clk-fractional-divider.c:147:25: sparse: sparse: Variable length array is used.
drivers/clk/clk-fractional-divider.c:195:25: sparse: sparse: Variable length array is used.
drivers/clk/clk-fractional-divider.c:196:25: sparse: sparse: Variable length array is used.
drivers/clk/clk-fractional-divider.c:205:17: sparse: sparse: Variable length array is used.
drivers/clk/clk-fractional-divider.c:206:17: sparse: sparse: Variable length array is used.
--
--
--
drivers/clocksource/ingenic-timer.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:188:32: sparse: sparse: Variable length array is used.
--
--
drivers/base/regmap/regcache-rbtree.c: note: in included file (through include/linux/cpumask.h, include/linux/smp.h, arch/mips/include/asm/cpu-type.h, ...):
--
drivers/base/regmap/regcache-flat.c: note: in included file:
--
drivers/crypto/marvell/octeontx/otx_cptpf_ucode.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
drivers/crypto/marvell/octeontx/otx_cptpf_ucode.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
drivers/crypto/marvell/octeontx/otx_cptpf_ucode.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
drivers/crypto/marvell/octeontx/otx_cptpf_ucode.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
--
--
--
drivers/gpio/gpiolib.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
drivers/gpio/gpiolib.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
include/linux/find.h:388:46: sparse: sparse: Variable length array is used.
include/linux/find.h:188:32: sparse: sparse: Variable length array is used.
drivers/gpio/gpiolib.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
--
drivers/gpio/gpio-nomadik.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
kernel/sched/build_utility.c: note: in included file:
kernel/sched/debug.c:624:17: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *[assigned] sd @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/debug.c:624:17: sparse: expected struct sched_domain *[assigned] sd
kernel/sched/debug.c:624:17: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/debug.c:952:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *tsk @@ got struct task_struct [noderef] __rcu *curr @@
kernel/sched/debug.c:952:9: sparse: expected struct task_struct *tsk
kernel/sched/debug.c:952:9: sparse: got struct task_struct [noderef] __rcu *curr
kernel/sched/debug.c:952:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *tsk @@ got struct task_struct [noderef] __rcu *curr @@
kernel/sched/debug.c:952:9: sparse: expected struct task_struct *tsk
kernel/sched/debug.c:952:9: sparse: got struct task_struct [noderef] __rcu *curr
kernel/sched/build_utility.c: note: in included file:
kernel/sched/topology.c:115:56: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:115:56: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:115:56: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:134:60: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:134:60: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:134:60: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:157:20: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:157:20: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:157:20: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:468:19: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct perf_domain *pd @@ got struct perf_domain [noderef] __rcu *pd @@
kernel/sched/topology.c:468:19: sparse: expected struct perf_domain *pd
kernel/sched/topology.c:468:19: sparse: got struct perf_domain [noderef] __rcu *pd
kernel/sched/topology.c:638:49: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sched_domain *parent @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:638:49: sparse: expected struct sched_domain *parent
kernel/sched/topology.c:638:49: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:723:50: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sched_domain *parent @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:723:50: sparse: expected struct sched_domain *parent
kernel/sched/topology.c:723:50: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:731:55: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain [noderef] __rcu *[noderef] __rcu child @@ got struct sched_domain *[assigned] tmp @@
kernel/sched/topology.c:731:55: sparse: expected struct sched_domain [noderef] __rcu *[noderef] __rcu child
kernel/sched/topology.c:731:55: sparse: got struct sched_domain *[assigned] tmp
kernel/sched/topology.c:744:29: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *[assigned] tmp @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:744:29: sparse: expected struct sched_domain *[assigned] tmp
kernel/sched/topology.c:744:29: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:749:20: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:749:20: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:749:20: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:770:13: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *[assigned] tmp @@ got struct sched_domain [noderef] __rcu *sd @@
kernel/sched/topology.c:770:13: sparse: expected struct sched_domain *[assigned] tmp
kernel/sched/topology.c:770:13: sparse: got struct sched_domain [noderef] __rcu *sd
kernel/sched/topology.c:932:70: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:932:70: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:932:70: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:961:59: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:961:59: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:961:59: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:1007:57: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:1007:57: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:1007:57: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:1009:25: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *sibling @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:1009:25: sparse: expected struct sched_domain *sibling
kernel/sched/topology.c:1009:25: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:1017:55: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:1017:55: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:1017:55: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:1019:25: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *sibling @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:1019:25: sparse: expected struct sched_domain *sibling
kernel/sched/topology.c:1019:25: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:1089:62: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sched_domain *sd @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:1089:62: sparse: expected struct sched_domain *sd
kernel/sched/topology.c:1089:62: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:1193:40: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sched_domain *child @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:1193:40: sparse: expected struct sched_domain *child
kernel/sched/topology.c:1193:40: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:1331:9: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *[assigned] sd @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:1331:9: sparse: expected struct sched_domain *[assigned] sd
kernel/sched/topology.c:1331:9: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:1680:43: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sched_domain [noderef] __rcu *child @@ got struct sched_domain *child @@
kernel/sched/topology.c:1680:43: sparse: expected struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:1680:43: sparse: got struct sched_domain *child
kernel/sched/topology.c:2470:31: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain [noderef] __rcu *parent @@ got struct sched_domain *sd @@
kernel/sched/topology.c:2470:31: sparse: expected struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:2470:31: sparse: got struct sched_domain *sd
kernel/sched/topology.c:2591:57: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *[assigned] sd @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:2591:57: sparse: expected struct sched_domain *[assigned] sd
kernel/sched/topology.c:2591:57: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:2612:56: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sched_domain *child @@ got struct sched_domain [noderef] __rcu *child @@
kernel/sched/topology.c:2612:56: sparse: expected struct sched_domain *child
kernel/sched/topology.c:2612:56: sparse: got struct sched_domain [noderef] __rcu *child
kernel/sched/topology.c:2611:57: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *[assigned] sd @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:2611:57: sparse: expected struct sched_domain *[assigned] sd
kernel/sched/topology.c:2611:57: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/topology.c:2666:57: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct sched_domain *[assigned] sd @@ got struct sched_domain [noderef] __rcu *parent @@
kernel/sched/topology.c:2666:57: sparse: expected struct sched_domain *[assigned] sd
kernel/sched/topology.c:2666:57: sparse: got struct sched_domain [noderef] __rcu *parent
kernel/sched/build_utility.c: note: in included file:
kernel/sched/build_utility.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, include/linux/smp.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
kernel/sched/build_utility.c: note: in included file:
kernel/sched/sched.h:2360:25: sparse: sparse: incompatible types in comparison expression (different address spaces):
kernel/sched/sched.h:2360:25: sparse: struct task_struct [noderef] __rcu *
kernel/sched/sched.h:2360:25: sparse: struct task_struct *
--
drivers/clk/ingenic/cgu.c:97:42: sparse: sparse: Variable length array is used.
drivers/clk/ingenic/cgu.c:102:27: sparse: sparse: Variable length array is used.
drivers/clk/ingenic/cgu.c:224:18: sparse: sparse: Variable length array is used.
drivers/clk/ingenic/cgu.c:227:18: sparse: sparse: Variable length array is used.
drivers/clk/ingenic/cgu.c:231:26: sparse: sparse: Variable length array is used.
drivers/clk/ingenic/cgu.c:345:26: sparse: sparse: Variable length array is used.
drivers/clk/ingenic/cgu.c:389:24: sparse: sparse: Variable length array is used.
drivers/clk/ingenic/cgu.c:423:31: sparse: sparse: Variable length array is used.
drivers/clk/ingenic/cgu.c:553:24: sparse: sparse: Variable length array is used.
--
kernel/irq/chip.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
--
kernel/irq/irq_sim.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
drivers/input/rmi4/rmi_driver.c: note: in included file (through include/linux/bitmap.h):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
drivers/input/rmi4/rmi_driver.c: note: in included file:
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
drivers/input/rmi4/rmi_driver.c: note: in included file (through include/linux/bitmap.h):
--
--
drivers/mfd/atmel-smc.c:57:32: sparse: sparse: Variable length array is used.
drivers/mfd/atmel-smc.c:120:27: sparse: sparse: Variable length array is used.
drivers/mfd/atmel-smc.c:159:25: sparse: sparse: Variable length array is used.
drivers/mfd/atmel-smc.c:198:25: sparse: sparse: Variable length array is used.
drivers/mfd/atmel-smc.c:236:25: sparse: sparse: Variable length array is used.
--
--
drivers/mtd/nand/bbt.c:111:38: sparse: sparse: Variable length array is used.
drivers/mtd/nand/bbt.c:116:20: sparse: sparse: Variable length array is used.
drivers/mtd/nand/bbt.c:122:28: sparse: sparse: Variable length array is used.
--
drivers/opp/cpu.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
drivers/pci/pci.c:1157:36: sparse: sparse: incorrect type in assignment (different base types) @@ expected restricted pci_power_t [usertype] current_state @@ got int @@
drivers/pci/pci.c:1157:36: sparse: expected restricted pci_power_t [usertype] current_state
drivers/pci/pci.c:1157:36: sparse: got int
drivers/pci/pci.c:1336:15: sparse: sparse: incorrect type in assignment (different base types) @@ expected restricted pci_power_t [assigned] [usertype] state @@ got int @@
drivers/pci/pci.c:1336:15: sparse: expected restricted pci_power_t [assigned] [usertype] state
drivers/pci/pci.c:1336:15: sparse: got int
drivers/pci/pci.c:1338:50: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1338:69: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1391:28: sparse: sparse: incorrect type in assignment (different base types) @@ expected restricted pci_power_t [usertype] current_state @@ got int @@
drivers/pci/pci.c:1391:28: sparse: expected restricted pci_power_t [usertype] current_state
drivers/pci/pci.c:1391:28: sparse: got int
drivers/pci/pci.c:1481:16: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1481:35: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1481:52: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1481:70: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1506:15: sparse: sparse: invalid assignment: |=
drivers/pci/pci.c:1506:15: sparse: left side has type unsigned short
drivers/pci/pci.c:1506:15: sparse: right side has type restricted pci_power_t
drivers/pci/pci.c:1518:28: sparse: sparse: incorrect type in assignment (different base types) @@ expected restricted pci_power_t [usertype] current_state @@ got int @@
drivers/pci/pci.c:1518:28: sparse: expected restricted pci_power_t [usertype] current_state
drivers/pci/pci.c:1518:28: sparse: got int
drivers/pci/pci.c:1535:13: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1535:21: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1537:18: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1537:26: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1560:13: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1560:22: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:1865:38: sparse: sparse: array of flexible structures
drivers/pci/pci.c:2343:44: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:2662:60: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:2663:30: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:2834:20: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:2834:38: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:2857:49: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:2857:67: sparse: sparse: restricted pci_power_t degrades to integer
drivers/pci/pci.c:4486:13: sparse: sparse: invalid assignment: |=
drivers/pci/pci.c:4486:13: sparse: left side has type unsigned short
drivers/pci/pci.c:4486:13: sparse: right side has type restricted pci_power_t
drivers/pci/pci.c:4491:13: sparse: sparse: invalid assignment: |=
drivers/pci/pci.c:4491:13: sparse: left side has type unsigned short
drivers/pci/pci.c:4491:13: sparse: right side has type restricted pci_power_t
drivers/pci/pci.c:1112:24: sparse: sparse: incorrect type in return expression (different base types) @@ expected int @@ got restricted pci_power_t [usertype] @@
drivers/pci/pci.c:1112:24: sparse: expected int
drivers/pci/pci.c:1112:24: sparse: got restricted pci_power_t [usertype]
drivers/pci/pci.c:1112:24: sparse: sparse: incorrect type in return expression (different base types) @@ expected int @@ got restricted pci_power_t [usertype] @@
drivers/pci/pci.c:1112:24: sparse: expected int
drivers/pci/pci.c:1112:24: sparse: got restricted pci_power_t [usertype]
drivers/pci/pci.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
--
drivers/perf/xgene_pmu.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:388:46: sparse: sparse: Variable length array is used.
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
--
--
--
drivers/mtd/nand/raw/nand_macronix.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
--
drivers/clk/spacemit/ccu_mix.c:193:16: sparse: sparse: Variable length array is used.
--
--
--
drivers/clk/sprd/pll.c:116:13: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:120:34: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:121:31: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:124:14: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:125:32: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:127:24: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:128:21: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:129:32: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:131:24: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:164:16: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:170:16: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:181:16: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:186:16: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:192:16: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:198:16: sparse: sparse: Variable length array is used.
drivers/clk/sprd/pll.c:210:16: sparse: sparse: Variable length array is used.
--
--
drivers/pinctrl/renesas/core.c:942:34: sparse: sparse: Variable length array is used.
drivers/pinctrl/renesas/core.c:1241:34: sparse: sparse: Variable length array is used.
--
drivers/pinctrl/renesas/pinctrl.c:527:17: sparse: sparse: Variable length array is used.
--
drivers/pci/controller/pcie-xilinx-dma-pl.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
drivers/pci/controller/pcie-xilinx-dma-pl.c: note: in included file (through include/linux/cpumask.h, arch/mips/include/asm/processor.h, arch/mips/include/asm/thread_info.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
--
drivers/pci/controller/dwc/pcie-designware-host.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, include/linux/smp.h, ...):
include/linux/find.h:69:31: sparse: sparse: Variable length array is used.
drivers/pci/controller/dwc/pcie-designware-host.c: note: in included file (through include/linux/cpumask.h, include/linux/smp.h, arch/mips/include/asm/cpu-type.h, ...):
include/linux/bitmap.h:488:25: sparse: sparse: Variable length array is used.
vim +209 include/linux/find.h
c56f97c5c71f17 include/linux/find.h Yury Norov [NVIDIA] 2025-06-19 48
19de85ef574c3a include/asm-generic/bitops/find.h Akinobu Mita 2011-05-26 49 #ifndef find_next_bit
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 50 /**
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 51 * find_next_bit - find the next set bit in a memory region
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 52 * @addr: The address to base the search on
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 53 * @size: The bitmap size in bits
6d7131bd52b3e0 include/linux/find.h Anna-Maria Behnsen 2022-04-11 54 * @offset: The bitnumber to start searching at
ec778edf97dcaa include/asm-generic/bitops/find.h Cody P Schafer 2013-11-12 55 *
ec778edf97dcaa include/asm-generic/bitops/find.h Cody P Schafer 2013-11-12 56 * Returns the bit number for the next set bit
ec778edf97dcaa include/asm-generic/bitops/find.h Cody P Schafer 2013-11-12 57 * If no bits are set, returns @size.
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 58 */
fda1dd3c54ef3c include/linux/find.h Yury Norov 2024-07-18 59 static __always_inline
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 60 unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 61 unsigned long offset)
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 62 {
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 63 if (small_const_nbits(size)) {
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 64 unsigned long val;
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 65
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 66 if (unlikely(offset >= size))
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 67 return size;
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 68
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 @69 val = *addr & GENMASK(size - 1, offset);
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 70 return val ? __ffs(val) : size;
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 71 }
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 72
e79864f3164c57 include/linux/find.h Yury Norov 2022-09-14 73 return _find_next_bit(addr, size, offset);
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 74 }
19de85ef574c3a include/asm-generic/bitops/find.h Akinobu Mita 2011-05-26 75 #endif
c7f612cdf091de include/asm-generic/bitops/find.h Akinobu Mita 2006-03-26 76
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 77 #ifndef find_next_and_bit
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 78 /**
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 79 * find_next_and_bit - find the next set bit in both memory regions
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 80 * @addr1: The first address to base the search on
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 81 * @addr2: The second address to base the search on
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 82 * @size: The bitmap size in bits
6d7131bd52b3e0 include/linux/find.h Anna-Maria Behnsen 2022-04-11 83 * @offset: The bitnumber to start searching at
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 84 *
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 85 * Returns the bit number for the next set bit
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 86 * If no bits are set, returns @size.
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 87 */
fda1dd3c54ef3c include/linux/find.h Yury Norov 2024-07-18 88 static __always_inline
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 89 unsigned long find_next_and_bit(const unsigned long *addr1,
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 90 const unsigned long *addr2, unsigned long size,
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 91 unsigned long offset)
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 92 {
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 93 if (small_const_nbits(size)) {
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 94 unsigned long val;
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 95
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 96 if (unlikely(offset >= size))
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 97 return size;
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 98
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 99 val = *addr1 & *addr2 & GENMASK(size - 1, offset);
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 100 return val ? __ffs(val) : size;
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 101 }
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 102
e79864f3164c57 include/linux/find.h Yury Norov 2022-09-14 103 return _find_next_and_bit(addr1, addr2, size, offset);
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 104 }
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 105 #endif
0ade34c37012ea include/asm-generic/bitops/find.h Clement Courbet 2018-02-06 106
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 107 #ifndef find_next_andnot_bit
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 108 /**
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 109 * find_next_andnot_bit - find the next set bit in *addr1 excluding all the bits
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 110 * in *addr2
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 111 * @addr1: The first address to base the search on
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 112 * @addr2: The second address to base the search on
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 113 * @size: The bitmap size in bits
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 114 * @offset: The bitnumber to start searching at
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 115 *
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 116 * Returns the bit number for the next set bit
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 117 * If no bits are set, returns @size.
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 118 */
fda1dd3c54ef3c include/linux/find.h Yury Norov 2024-07-18 119 static __always_inline
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 120 unsigned long find_next_andnot_bit(const unsigned long *addr1,
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 121 const unsigned long *addr2, unsigned long size,
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 122 unsigned long offset)
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 123 {
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 124 if (small_const_nbits(size)) {
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 125 unsigned long val;
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 126
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 127 if (unlikely(offset >= size))
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 128 return size;
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 129
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 130 val = *addr1 & ~*addr2 & GENMASK(size - 1, offset);
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 131 return val ? __ffs(val) : size;
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 132 }
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 133
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 134 return _find_next_andnot_bit(addr1, addr2, size, offset);
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 135 }
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 136 #endif
90d482908eedd5 include/linux/find.h Valentin Schneider 2022-10-03 137
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 138 #ifndef find_next_or_bit
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 139 /**
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 140 * find_next_or_bit - find the next set bit in either memory regions
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 141 * @addr1: The first address to base the search on
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 142 * @addr2: The second address to base the search on
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 143 * @size: The bitmap size in bits
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 144 * @offset: The bitnumber to start searching at
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 145 *
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 146 * Returns the bit number for the next set bit
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 147 * If no bits are set, returns @size.
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 148 */
fda1dd3c54ef3c include/linux/find.h Yury Norov 2024-07-18 149 static __always_inline
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 150 unsigned long find_next_or_bit(const unsigned long *addr1,
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 151 const unsigned long *addr2, unsigned long size,
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 152 unsigned long offset)
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 153 {
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 154 if (small_const_nbits(size)) {
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 155 unsigned long val;
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 156
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 157 if (unlikely(offset >= size))
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 158 return size;
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 159
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 160 val = (*addr1 | *addr2) & GENMASK(size - 1, offset);
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 161 return val ? __ffs(val) : size;
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 162 }
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 163
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 164 return _find_next_or_bit(addr1, addr2, size, offset);
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 165 }
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 166 #endif
1470afefc3c42d include/linux/find.h Dave Chinner 2023-03-15 167
19de85ef574c3a include/asm-generic/bitops/find.h Akinobu Mita 2011-05-26 168 #ifndef find_next_zero_bit
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 169 /**
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 170 * find_next_zero_bit - find the next cleared bit in a memory region
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 171 * @addr: The address to base the search on
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 172 * @size: The bitmap size in bits
6d7131bd52b3e0 include/linux/find.h Anna-Maria Behnsen 2022-04-11 173 * @offset: The bitnumber to start searching at
ec778edf97dcaa include/asm-generic/bitops/find.h Cody P Schafer 2013-11-12 174 *
ec778edf97dcaa include/asm-generic/bitops/find.h Cody P Schafer 2013-11-12 175 * Returns the bit number of the next zero bit
ec778edf97dcaa include/asm-generic/bitops/find.h Cody P Schafer 2013-11-12 176 * If no bits are zero, returns @size.
d852a6afd91fc9 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 177 */
fda1dd3c54ef3c include/linux/find.h Yury Norov 2024-07-18 178 static __always_inline
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 179 unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 180 unsigned long offset)
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 181 {
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 182 if (small_const_nbits(size)) {
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 183 unsigned long val;
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 184
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 185 if (unlikely(offset >= size))
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 186 return size;
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 187
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 188 val = *addr | ~GENMASK(size - 1, offset);
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 189 return val == ~0UL ? size : ffz(val);
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 190 }
277a20a498d307 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 191
e79864f3164c57 include/linux/find.h Yury Norov 2022-09-14 192 return _find_next_zero_bit(addr, size, offset);
5c88af59f9abc2 include/asm-generic/bitops/find.h Yury Norov 2021-05-06 193 }
19de85ef574c3a include/asm-generic/bitops/find.h Akinobu Mita 2011-05-26 194 #endif
c7f612cdf091de include/asm-generic/bitops/find.h Akinobu Mita 2006-03-26 195
b7ec62d7ee0f0b include/asm-generic/bitops/find.h Yury Norov 2021-08-14 196 #ifndef find_first_bit
708ff2a0097b02 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 197 /**
708ff2a0097b02 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 198 * find_first_bit - find the first set bit in a memory region
708ff2a0097b02 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 199 * @addr: The address to start the search at
ec778edf97dcaa include/asm-generic/bitops/find.h Cody P Schafer 2013-11-12 200 * @size: The maximum number of bits to search
708ff2a0097b02 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 201 *
708ff2a0097b02 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 202 * Returns the bit number of the first set bit.
ec778edf97dcaa include/asm-generic/bitops/find.h Cody P Schafer 2013-11-12 203 * If no bits are set, returns @size.
708ff2a0097b02 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 204 */
fda1dd3c54ef3c include/linux/find.h Yury Norov 2024-07-18 205 static __always_inline
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 206 unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 207 {
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 208 if (small_const_nbits(size)) {
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 @209 unsigned long val = *addr & GENMASK(size - 1, 0);
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 210
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 211 return val ? __ffs(val) : size;
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 212 }
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 213
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 214 return _find_first_bit(addr, size);
2cc7b6a44ac21d include/asm-generic/bitops/find.h Yury Norov 2021-05-06 215 }
b7ec62d7ee0f0b include/asm-generic/bitops/find.h Yury Norov 2021-08-14 216 #endif
708ff2a0097b02 include/asm-generic/bitops/find.h Akinobu Mita 2010-09-29 217
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
|
{
"author": "kernel test robot <lkp@intel.com>",
"date": "Thu, 22 Jan 2026 12:41:22 +0800",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Wed, Jan 21, 2026 at 07:24:51PM +0000, David Laight wrote:
The #ifndef in vdso/bits.h is not much better IMO.
Given that there a multiple nicer options why not use on of those?
That is a bug. The vdso code should only include the vdso/ namespace.
Right now the inclusions are all over the place. I'd like to clean that
up at some point.
I don't understand "code version specific".
There are various issues with including normal kernel headers from the vDSO.
Symbols defined in terms of kconfig options, like BITS_PER_LONG using
CONFIG_64BIT are wrong in a compat vDSO.
|
{
"author": "Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <thomas.weissschuh@linutronix.de>",
"date": "Thu, 22 Jan 2026 08:39:42 +0100",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Thu, 22 Jan 2026 09:11:53 +0800
kernel test robot <lkp@intel.com> wrote:
...
This might be a real bug.
The bit of mm.h is:
#define PP_DMA_INDEX_SHIFT (1 + __fls(PP_SIGNATURE - POISON_POINTER_DELTA))
#if POISON_POINTER_DELTA > 0
/* PP_SIGNATURE includes POISON_POINTER_DELTA, so limit the size of the DMA
* index to not overlap with that if set
*/
#define PP_DMA_INDEX_BITS MIN(32, __ffs(POISON_POINTER_DELTA) - PP_DMA_INDEX_SHIFT)
#else
/* Use the lowest bit of PAGE_OFFSET if there's at least 8 bits available; see above */
#define PP_DMA_INDEX_MIN_OFFSET (1 << (PP_DMA_INDEX_SHIFT + 8))
#define PP_DMA_INDEX_BITS ((__builtin_constant_p(PAGE_OFFSET) && \
PAGE_OFFSET >= PP_DMA_INDEX_MIN_OFFSET && \
!(PAGE_OFFSET & (PP_DMA_INDEX_MIN_OFFSET - 1))) ? \
MIN(32, __ffs(PAGE_OFFSET) - PP_DMA_INDEX_SHIFT) : 0)
#endif
#define PP_DMA_INDEX_MASK GENMASK(PP_DMA_INDEX_BITS + PP_DMA_INDEX_SHIFT - 1, \
PP_DMA_INDEX_SHIFT)
I've no idea what the values are, but the 'hi' bit number must exceed that
of 'long'.
The __ffs() probably stop it being an 'integer constant expression'
making it just a 'compile time constant' - which I added a test for.
David
|
{
"author": "David Laight <david.laight.linux@gmail.com>",
"date": "Thu, 22 Jan 2026 10:25:54 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Thu, 22 Jan 2026 09:23:16 +0800
kernel test robot <lkp@intel.com> wrote:
...
Unless I change BIT() back I'll change that to a static_assert().
David
|
{
"author": "David Laight <david.laight.linux@gmail.com>",
"date": "Thu, 22 Jan 2026 10:30:29 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Thu, 22 Jan 2026 12:41:22 +0800
kernel test robot <lkp@intel.com> wrote:
Can we stop sparse complaining about sizeof(VLA) ?
David
|
{
"author": "David Laight <david.laight.linux@gmail.com>",
"date": "Thu, 22 Jan 2026 10:33:37 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Thu, Jan 22, 2026 at 10:33:37AM +0000, David Laight wrote:
First of all, the LKP should install the fork of sparse by Al Viro. That will
fix tons of warnings that are related to modules and speed up the process
itself.
--
With Best Regards,
Andy Shevchenko
|
{
"author": "Andy Shevchenko <andriy.shevchenko@linux.intel.com>",
"date": "Thu, 22 Jan 2026 16:26:44 +0200",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Thu, 22 Jan 2026 16:26:44 +0200
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
The problem I have is I want to generate a compile time error inside:
__builtin_choose_expr(__is_constexpr(x), x && error_a(),
statically_true(y) && error_b());
Neither static_assert() nor a negative bitfield can be used in error_a()
because they are errors when x isn't isn't a 'constexpr',
There is less of a problem for error_b() it can contain a function call,
but can't contain {( ...)}.
One of the compiler complained about sizeof (char [-!!(expr)]) as well.
I'm not sure of anything else that can be use to get an error.
I could use 0 >> -1 but that is only a warning, at least the error message
is related to the bug.
Any other ideas?
David
|
{
"author": "David Laight <david.laight.linux@gmail.com>",
"date": "Thu, 22 Jan 2026 14:55:56 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Thu, 22 Jan 2026 10:25:54 +0000
David Laight <david.laight.linux@gmail.com> wrote:
I've managed to do an s390 cross build.
It is all quite obvious really.
For s390 PAGE_OFFSET is usually zero (I think kernel and user mappings are separate?).
This make PP_DMA_INDEX_BITS 0.
PP_SIGNATURE is 64 - so PP_DMA_INDEX_SHIFT is 7.
So it is doing GENMASK(6, 7) and, I think, expecting to get zero.
But that is taken a mistyped GENMASK(7, 6) and treated as an error.
If I rewrite __fls() and __ffs() to return 'integer constant expressions'
when the input is one I think it would always have failed.
A comment a few lines higher suggests that the code expects the mask to
be zero in this case - and handles it properly.
David
|
{
"author": "David Laight <david.laight.linux@gmail.com>",
"date": "Thu, 22 Jan 2026 20:10:20 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Thu, Jan 22, 2026 at 10:33:37AM +0000, David Laight wrote:
Got it, we will avoid the direct report this 'sparse: Variable length array is used' warning.
|
{
"author": "Philip Li <philip.li@intel.com>",
"date": "Fri, 23 Jan 2026 09:24:50 +0800",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Thu, Jan 22, 2026 at 04:26:44PM +0200, Andy Shevchenko wrote:
Thanks Andy, i will switch to the repo from Al Viro for sparse.
|
{
"author": "Philip Li <philip.li@intel.com>",
"date": "Fri, 23 Jan 2026 09:25:36 +0800",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
Adding the relevant parties to the discussion:
+To: Al Viro
+To: Chris Li
On 23/01/2026 at 02:25, Philip Li wrote:
Al Viro's fork just adds 8 commit on top of the upstream sparse repo.
Wouldn't it be possible to just merge those?
That would be much less confusing.
Yours sincerely,
Vincent Mailhol
|
{
"author": "Vincent Mailhol <mailhol@kernel.org>",
"date": "Fri, 23 Jan 2026 09:01:04 +0100",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Fri, Jan 23, 2026 at 09:01:04AM +0100, Vincent Mailhol wrote:
Ideally yes, but you also should kick the distro's asses to update it, and
the sparse should bump its version...
Seems Al become a sparse maintainer de facto :-)
--
With Best Regards,
Andy Shevchenko
|
{
"author": "Andy Shevchenko <andriy.shevchenko@linux.intel.com>",
"date": "Fri, 23 Jan 2026 10:11:19 +0200",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Fri, Jan 23, 2026 at 10:11:19AM +0200, Andy Shevchenko wrote:
Huh? What happened to Chris? FWIW, I do have some followups to that series
sitting locally; need to get that finished (mostly for proper __VA_OPT__
handling; that got stalled on the lovely corner cases where the interplay
with side effects of macro expansion is really nasty - gcc and clang do
not agree and gcc is arguably buggy) and posted.
I've done quite a bit of sparse work over the years, but I would rather
prefer somebody else as overall maintainer, TYVM...
|
{
"author": "Al Viro <viro@zeniv.linux.org.uk>",
"date": "Fri, 23 Jan 2026 08:20:27 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Fri, Jan 23, 2026 at 08:20:27AM +0000, Al Viro wrote:
I don't know, but upstream sparse haven't applied any solution for
MODULE*("FOO") stuff, nor reaction on my ping in that discussion
(I did it like week or so ago).
Thanks for doing all this!
--
With Best Regards,
Andy Shevchenko
|
{
"author": "Andy Shevchenko <andriy.shevchenko@linux.intel.com>",
"date": "Fri, 23 Jan 2026 10:24:01 +0200",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On 23/01/2026 at 09:24, Andy Shevchenko wrote:
After the project hiatus, I can imagine that there is some confusion :)
But Chris is back in his role of maintainer since September 2025. See:
- https://lore.kernel.org/linux-sparse/CACePvbXDO1ZybDu3RaFhED9D-9gC6LTMpWrxoh5xD+ZO5SLdzA@mail.gmail.com/
- https://git.kernel.org/pub/scm/devel/sparse/sparse.git/commit/?id=67f0a03cee4637e495151c48a02be642a158cbbb
I am out of context here, but were the correct people CCed?
Yours sincerely,
Vincent Mailhol
|
{
"author": "Vincent Mailhol <mailhol@kernel.org>",
"date": "Fri, 23 Jan 2026 09:32:39 +0100",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Fri, Jan 23, 2026 at 09:32:39AM +0100, Vincent Mailhol wrote:
...
My ping: https://lore.kernel.org/all/aV9vo7_turBr84bs@black.igk.intel.com/
But now I realised that there was another version of the series, and Chris
seems active there.
https://lore.kernel.org/all/CACePvbU5Pqo=bw_j8arOq16o1JBOSwPtuMZBVozy4FV7YsSLGw@mail.gmail.com/
I dunno.
--
With Best Regards,
Andy Shevchenko
|
{
"author": "Andy Shevchenko <andriy.shevchenko@linux.intel.com>",
"date": "Fri, 23 Jan 2026 10:46:37 +0200",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Wed, Jan 21, 2026 at 02:57:22PM +0000, david.laight.linux@gmail.com wrote:
Thanks David,
Other than the motivation above, I appreciate that this removes two
#ifdefs, improving readability (subjective) and compile coverage
(objective) of this code.
As an aside: I'm Not sure what your merge plan is for this patchset, and
only it and the cover letter hit my inbox, so I'm missing context. But
from a Networking PoV it seems that it could be sent as a stand-alone patch
to the iwl tree.
Regardless, feel free to add:
Reviewed-by: Simon Horman <horms@kernel.org>
...
|
{
"author": "Simon Horman <horms@kernel.org>",
"date": "Fri, 23 Jan 2026 15:44:25 +0000",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH next 00/14] bits: De-bloat expansion of GENMASK()
|
From: David Laight <david.laight.linux@gmail.com>
The expansion of GENMASK() is a few hundred bytes, this is often multiplied
when the value is passed to other #defines (eg FIELD_PREP).
Part of the size is due to the compile-type check (for reversed arguments),
the rest from the way the value is defined.
Nothing in these patches changes the code the compiler sees - just the
way the constants get defined.
Changing GENMASK(hi, lo) to (2 << hi) - (1 << lo) is left for further study.
I looked at getting the compiler to check for reversed arguments using
(0 >> (hi - lo)) instead of const_true(lo > hi). While checking that it
was always optimised away I discovered that you don't get an error message
if the values are only 'compile time constants', worse clang starts
throwing code away, generation an empty function for:
int f(u32 x) {int n = 32; return x >> n; }
(Shifts by more than width are 'undefined behaviour', so what clang
does is technically valid - but not friendly or expected.)
So I added extra checks to both GENMASK() and BITxxx() to detect this
at compile time. But this bloats the output - the opposite of what I
was trying to achieve.
However these are all compile-time checks that are actually unlikely
to detect anything, they don't need to be done on every build.
I've mitigated this by adding W=c (cf W=[123e]) to the main Makefile
(adding -DKBUILD_EXTRA_WARNc) and defaulting to W=c for W=1 builds.
Adding checks to BIT() makes it no longer a pre-processor constant
so can no longer be used in #if statements (when W=c) is set.
This required minor changes to 3 files.
At some point the definition of BIT() was moved to vdso/bits.h
(followed by that for BIT_ULL()), but then the fixed size BIT_Unn()
were added to bits.h.
I've moved BIT_ULL() back to linux/bits.h and made the version of
BIT() in linux/bits.h be preferred if both files get included.
Note that the x86-64 allmodconfig build suceeds if vdso/bits.h
is empty - everything includes linux/bits.h first.
I found two non-vdso files that included vdso/bits.h and changed
them to use linux/bits.h.
GENMASK_U8() and BIT_U8() cast their result to (u8), this isn't
a good idea. While the 'type of the expression' is 'u8', integer
promotion makes the 'type of the value' 'signed int'.
This means that in code like:
u64 v = BIT_U8(7) << 24;
the value is sign extended and all the high bits are set.
Instead change the type of the xxx_U8/U16 macros to 'unsigned int'
so that the sign extension cannot happen.
The compile-time check on the bit number is still present.
For assembler files where GENMASK() can be used for constants
the expansions from uapi/linux/bits.h were used.
However these contain BITS_PER_LONG and BITS_PER_LONG_LONG which
make no sense since the assembler doesn't have sized arithmetic.
Replace with GENMASK(hi, lo) (2 << (hi)) - (1 << (lo)) which has
the correct value without knowing the size of the integers.
The kunit tests all check compile-time values.
I've changed them to use BUILD_BUG_ON().
David Laight (14):
overflow: Reduce expansion of __type_max()
kbuild: Add W=c for additional compile time checks
media: videobuf2-core: Use static_assert() for sanity check
media: atomisp: Use static_assert() for sanity check
ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD
asm-generic: include linux/bits.h not vdso/bits.h
x86/tlb: include linux/bits.h not vdso/bits.h
bits: simplify GENMASK_TYPE()
bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values
bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx()
bit: Strengthen compile-time tests in GENMASK() and BIT()
bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h
test_bits: Change all the tests to be compile-time tests
test_bits: include some invalid input tests for GENMASK_INPUT_CHECK()
arch/x86/include/asm/tlb.h | 2 +-
.../media/common/videobuf2/videobuf2-core.c | 6 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 17 +--
.../fixedbds_1.0/ia_css_fixedbds_param.h | 5 +-
include/asm-generic/thread_info_tif.h | 2 +-
include/linux/bits.h | 88 ++++++++----
include/linux/overflow.h | 2 +-
include/vdso/bits.h | 2 +-
lib/tests/test_bits.c | 130 +++++++++++-------
scripts/Makefile.warn | 12 +-
10 files changed, 162 insertions(+), 104 deletions(-)
--
2.39.5
|
On Wed, Jan 21, 2026 at 02:57:18PM +0000, david.laight.linux@gmail.com wrote:
Thanks!
Reviewed-by: Yury Norov <ynorov@nvidia.com>
|
{
"author": "Yury Norov <ynorov@nvidia.com>",
"date": "Mon, 2 Feb 2026 11:45:28 -0500",
"thread_id": "20260121145731.3623-1-david.laight.linux@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
properly saved. This affects both rustdoc and doctests builds.
However, `fixed-x18` is an ARM64-specific ABI modifier related to the
x18 register reservation (used for Shadow Call Stack). Currently, this
workaround is applied unconditionally on all architectures, which is
incorrect and may cause issues on non-ARM64 builds.
Restrict the workaround to only apply when building for arm64
(SRCARCH=arm64).
Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83..2bd547611 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
+rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
HeeSu Kim <mlksvender@gmail.com> writes:
Are we sure this is in the correct commit hash? It is not present on
mainline.
Maybe it should be this one?
Fixes: abbf9a449441 ("rust: workaround `rustdoc` target modifiers bug")
Cheers,
C. Mitrodimas
|
{
"author": "Charalampos Mitrodimas <charmitro@posteo.net>",
"date": "Mon, 02 Feb 2026 13:59:54 +0000",
"thread_id": "20260203014613.2708234-1-mlksvender@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
properly saved. This affects both rustdoc and doctests builds.
However, `fixed-x18` is an ARM64-specific ABI modifier related to the
x18 register reservation (used for Shadow Call Stack). Currently, this
workaround is applied unconditionally on all architectures, which is
incorrect and may cause issues on non-ARM64 builds.
Restrict the workaround to only apply when building for arm64
(SRCARCH=arm64).
Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83..2bd547611 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
+rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
On Tue, Feb 03, 2026, C. Mitrodimas wrote:
You're right. I mistakenly used a commit hash from my local branch.
I'll send a v2 with the correct Fixes tag.
|
{
"author": "HeeSu Kim <mlksvender@gmail.com>",
"date": "Tue, 3 Feb 2026 08:17:05 +0900",
"thread_id": "20260203014613.2708234-1-mlksvender@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
properly saved. This affects both rustdoc and doctests builds.
However, `fixed-x18` is an ARM64-specific ABI modifier related to the
x18 register reservation (used for Shadow Call Stack). Currently, this
workaround is applied unconditionally on all architectures, which is
incorrect and may cause issues on non-ARM64 builds.
Restrict the workaround to only apply when building for arm64
(SRCARCH=arm64).
Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83..2bd547611 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
+rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
On Mon, Feb 2, 2026 at 2:21 PM HeeSu Kim <mlksvender@gmail.com> wrote:
Could you please elaborate on the issues you are seeing, e.g. how to
reproduce them?
The flag is only used to silence errors from checks that were added to
`rustc` and it is ignored otherwise (that is why the workaround was
written like that).
Thank you!
Cheers,
Miguel
|
{
"author": "Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>",
"date": "Mon, 2 Feb 2026 15:20:01 +0100",
"thread_id": "20260203014613.2708234-1-mlksvender@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
properly saved. This affects both rustdoc and doctests builds.
However, `fixed-x18` is an ARM64-specific ABI modifier related to the
x18 register reservation (used for Shadow Call Stack). Currently, this
workaround is applied unconditionally on all architectures, which is
incorrect and may cause issues on non-ARM64 builds.
Restrict the workaround to only apply when building for arm64
(SRCARCH=arm64).
Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83..2bd547611 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
+rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
On Mon Feb 2, 2026 at 10:21 PM GMT, HeeSu Kim wrote:
It looks like this bug has been fixed upstream already. While you're at it,
would you mind also add code so that we stop applying the workaround for
versions with bug fixed already?
Thanks,
Gary
|
{
"author": "\"Gary Guo\" <gary@garyguo.net>",
"date": "Mon, 02 Feb 2026 14:24:31 +0000",
"thread_id": "20260203014613.2708234-1-mlksvender@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
properly saved. This affects both rustdoc and doctests builds.
However, `fixed-x18` is an ARM64-specific ABI modifier related to the
x18 register reservation (used for Shadow Call Stack). Currently, this
workaround is applied unconditionally on all architectures, which is
incorrect and may cause issues on non-ARM64 builds.
Restrict the workaround to only apply when building for arm64
(SRCARCH=arm64).
Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83..2bd547611 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
+rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
On Tue, Feb 03, 2026, Gary Guo wrote:
Sure, I'll check which Rust version includes the fix and send a patch
with the requested changes.
Best regards,
HeeSu Kim
|
{
"author": "HeeSu Kim <mlksvender@gmail.com>",
"date": "Tue, 3 Feb 2026 08:45:35 +0900",
"thread_id": "20260203014613.2708234-1-mlksvender@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
properly saved. This affects both rustdoc and doctests builds.
However, `fixed-x18` is an ARM64-specific ABI modifier related to the
x18 register reservation (used for Shadow Call Stack). Currently, this
workaround is applied unconditionally on all architectures, which is
incorrect and may cause issues on non-ARM64 builds.
Restrict the workaround to only apply when building for arm64
(SRCARCH=arm64).
Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83..2bd547611 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
+rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` workaround was added to
handle a rustdoc bug (rust-lang/rust#144521) where target modifiers
were not properly saved.
This bug was fixed in Rust 1.90.0 (rust-lang/rust#144523). Restrict
the workaround to only apply for Rust 1.88.x and 1.89.x versions that
are affected by the bug, avoiding unnecessary flags on newer compiler
versions.
Suggested-by: Gary Guo <gary@garyguo.net>
Fixes: abbf9a449441 ("rust: workaround `rustdoc` target modifiers bug")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83454..55e2dc865207 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The bug was fixed in Rust 1.90.0, so only apply for 1.88.x and 1.89.x.
+rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),$(if $(call test-lt,$(CONFIG_RUSTC_VERSION),109000),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
{
"author": "HeeSu Kim <mlksvender@gmail.com>",
"date": "Tue, 3 Feb 2026 09:21:16 +0900",
"thread_id": "20260203014613.2708234-1-mlksvender@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
properly saved. This affects both rustdoc and doctests builds.
However, `fixed-x18` is an ARM64-specific ABI modifier related to the
x18 register reservation (used for Shadow Call Stack). Currently, this
workaround is applied unconditionally on all architectures, which is
incorrect and may cause issues on non-ARM64 builds.
Restrict the workaround to only apply when building for arm64
(SRCARCH=arm64).
Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83..2bd547611 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
+rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
On Mon, Feb 2, 2026 at 4:21 PM HeeSu Kim <mlksvender@gmail.com> wrote:
Normally these references should be full links (i.e. a tag), since we
do not have "autolinking" like GitHub e.g.
Link: https://........ [1]
Then you can use [1] above instead of the parenthesis.
To clarify a bit: avoiding the flags is good, but I think avoiding the
skipping of the checks that the flag does is what is more important
(i.e. if it were just the former advantage, I would say it is not
worth the complexity of the added tests).
This is very minor and it is fine without a change, but for
completeness: for Suggested-by we generally add a Link: after that
tag, i.e. to lore.kernel.org to the message where Gary suggested it in
this case.
I think this is not really a fix anymore, i.e. nothing is broken, and
instead it is more of a feature, as far as I understand: avoiding to
skip the silencing of the checks.
If you added the tag to suggest that the patch should be backported to
stable kernels, then in these cases an explicit Cc: stable@ may be
added, mentioning the versions where this should go, e.g. in this
case:
Cc: stable@vger.kernel.org # Useful in 6.18.y and later.
(I used "Useful" instead of my usual "Needed" since it is not critical
to backport -- but please correct me if I am wrong).
By the way, I wonder if we would want at least a `rustc-max-version`
function or instead a range-based one for this sort of test. It is not
a blocker for this patch, but we may want to limit other workarounds
too (e.g. the one below this one).
Cc'ing Kbuild since I don't recall we have that for C compilers, so
there may be a reason for that.
Thanks for the patch!
Cheers,
Miguel
|
{
"author": "Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>",
"date": "Mon, 2 Feb 2026 17:00:59 +0100",
"thread_id": "20260203014613.2708234-1-mlksvender@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64
|
The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
properly saved. This affects both rustdoc and doctests builds.
However, `fixed-x18` is an ARM64-specific ABI modifier related to the
x18 register reservation (used for Shadow Call Stack). Currently, this
workaround is applied unconditionally on all architectures, which is
incorrect and may cause issues on non-ARM64 builds.
Restrict the workaround to only apply when building for arm64
(SRCARCH=arm64).
Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")
Signed-off-by: HeeSu Kim <mlksvender@gmail.com>
---
rust/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile
index 5c0155b83..2bd547611 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -136,7 +136,8 @@ pin_init-flags := \
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
-rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
+# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
+rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
--
2.52.0
|
On Mon, 3 Feb 2026, Miguel Ojeda wrote:
Thanks for the detailed feedback.
For v3, I will:
- Use full Link: tags for GitHub references instead of shorthand
- Add Link: tag after Suggested-by pointing to Gary's lore message
- Remove the Fixes: tag
- Add Cc: stable@vger.kernel.org # Useful in 6.18.y and later.
Regarding rustc-max-version, it would be useful for reading the code.
I'll wait for Kbuild maintainers' reply.
Best regards,
HeeSu Kim
|
{
"author": "HeeSu Kim <mlksvender@gmail.com>",
"date": "Tue, 3 Feb 2026 10:46:13 +0900",
"thread_id": "20260203014613.2708234-1-mlksvender@gmail.com.mbox.gz"
}
|
lkml
|
[PATCH v2] PCI: s32g: Fix ports parsing
|
No error return is missing after the loop resulting in removing the
ports from the list.
Fixes: 5cbc7d3e316e ("PCI: s32g: Add NXP S32G PCIe controller driver (RC)")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
Change since v1:
- handle correctly the case when there is no child port
drivers/pci/controller/dwc/pcie-nxp-s32g.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-nxp-s32g.c b/drivers/pci/controller/dwc/pcie-nxp-s32g.c
index 47745749f75c..b3ec38099fa3 100644
--- a/drivers/pci/controller/dwc/pcie-nxp-s32g.c
+++ b/drivers/pci/controller/dwc/pcie-nxp-s32g.c
@@ -282,12 +282,12 @@ static int s32g_pcie_parse_ports(struct device *dev, struct s32g_pcie *s32g_pp)
ret = s32g_pcie_parse_port(s32g_pp, of_port);
if (ret)
- goto err_port;
+ break;
}
-err_port:
- list_for_each_entry_safe(port, tmp, &s32g_pp->ports, list)
- list_del(&port->list);
+ if (ret)
+ list_for_each_entry_safe(port, tmp, &s32g_pp->ports, list)
+ list_del(&port->list);
return ret;
}
--
2.43.0
|
On Mon, Feb 02, 2026 at 04:10:50PM +0100, Vincent Guittot wrote:
break and goto is logical equal here. So only need below if (ret).
Frank
|
{
"author": "Frank Li <Frank.li@nxp.com>",
"date": "Mon, 2 Feb 2026 12:42:46 -0500",
"thread_id": "aYDiFpGT5hEDDFhV@lizhi-Precision-Tower-5810.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
This file actually implements irq remapping, so rename to more appropriate
hyperv-irq.c. A new file named hyperv-iommu.c will be introduced later.
Also, move CONFIG_IRQ_REMAP out of the file and add to Makefile.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
MAINTAINERS | 2 +-
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/{hyperv-iommu.c => hyperv-irq.c} | 4 ----
4 files changed, 3 insertions(+), 6 deletions(-)
rename drivers/iommu/{hyperv-iommu.c => hyperv-irq.c} (99%)
diff --git a/MAINTAINERS b/MAINTAINERS
index 5b11839cba9d..381a0e086382 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11741,7 +11741,7 @@ F: drivers/hid/hid-hyperv.c
F: drivers/hv/
F: drivers/infiniband/hw/mana/
F: drivers/input/serio/hyperv-keyboard.c
-F: drivers/iommu/hyperv-iommu.c
+F: drivers/iommu/hyperv-irq.c
F: drivers/net/ethernet/microsoft/
F: drivers/net/hyperv/
F: drivers/pci/controller/pci-hyperv-intf.c
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 99095645134f..b4cc2b42b338 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -355,6 +355,7 @@ config HYPERV_IOMMU
bool "Hyper-V IRQ Handling"
depends on HYPERV && X86
select IOMMU_API
+ select IRQ_REMAP
default HYPERV
help
Stub IOMMU driver to handle IRQs to support Hyper-V Linux
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 8e8843316c4b..598c39558e7d 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -30,7 +30,7 @@ obj-$(CONFIG_TEGRA_IOMMU_SMMU) += tegra-smmu.o
obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
-obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
+obj-$(CONFIG_HYPERV_IOMMU) += hyperv-irq.o
obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o
obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o
diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-irq.c
similarity index 99%
rename from drivers/iommu/hyperv-iommu.c
rename to drivers/iommu/hyperv-irq.c
index 0961ac805944..1944440a5004 100644
--- a/drivers/iommu/hyperv-iommu.c
+++ b/drivers/iommu/hyperv-irq.c
@@ -24,8 +24,6 @@
#include "irq_remapping.h"
-#ifdef CONFIG_IRQ_REMAP
-
/*
* According 82093AA IO-APIC spec , IO APIC has a 24-entry Interrupt
* Redirection Table. Hyper-V exposes one single IO-APIC and so define
@@ -330,5 +328,3 @@ static const struct irq_domain_ops hyperv_root_ir_domain_ops = {
.alloc = hyperv_root_irq_remapping_alloc,
.free = hyperv_root_irq_remapping_free,
};
-
-#endif
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:16 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Many PCI passthru related hypercalls require partition id of the target
guest. Guests are actually managed by MSHV driver and the partition id
is only maintained there. Add a field in the partition struct in MSHV
driver to save the tgid of the VMM process creating the partition,
and add a function there to retrieve partition id if valid VMM tgid.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
drivers/hv/mshv_root.h | 1 +
drivers/hv/mshv_root_main.c | 35 +++++++++++++++++++++++++++-------
include/asm-generic/mshyperv.h | 1 +
3 files changed, 30 insertions(+), 7 deletions(-)
diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index 3c1d88b36741..c3753b009fd8 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -134,6 +134,7 @@ struct mshv_partition {
struct mshv_girq_routing_table __rcu *pt_girq_tbl;
u64 isolation_type;
+ pid_t pt_vmm_tgid;
bool import_completed;
bool pt_initialized;
};
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 1134a82c7881..83c7bad269a0 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1823,6 +1823,20 @@ mshv_partition_release(struct inode *inode, struct file *filp)
return 0;
}
+/* Given a process tgid, return partition id if it is a VMM process */
+u64 mshv_pid_to_partid(pid_t tgid)
+{
+ struct mshv_partition *pt;
+ int i;
+
+ hash_for_each_rcu(mshv_root.pt_htable, i, pt, pt_hnode)
+ if (pt->pt_vmm_tgid == tgid)
+ return pt->pt_id;
+
+ return HV_PARTITION_ID_INVALID;
+}
+EXPORT_SYMBOL_GPL(mshv_pid_to_partid);
+
static int
add_partition(struct mshv_partition *partition)
{
@@ -1987,13 +2001,20 @@ mshv_ioctl_create_partition(void __user *user_arg, struct device *module_dev)
goto delete_partition;
ret = mshv_init_async_handler(partition);
- if (!ret) {
- ret = FD_ADD(O_CLOEXEC, anon_inode_getfile("mshv_partition",
- &mshv_partition_fops,
- partition, O_RDWR));
- if (ret >= 0)
- return ret;
- }
+ if (ret)
+ goto rem_partition;
+
+ ret = FD_ADD(O_CLOEXEC, anon_inode_getfile("mshv_partition",
+ &mshv_partition_fops,
+ partition, O_RDWR));
+ if (ret < 0)
+ goto rem_partition;
+
+ partition->pt_vmm_tgid = current->tgid;
+
+ return ret;
+
+rem_partition:
remove_partition(partition);
delete_partition:
hv_call_delete_partition(partition->pt_id);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index ecedab554c80..e46a38916e76 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -211,6 +211,7 @@ void __init ms_hyperv_late_init(void);
int hv_common_cpu_init(unsigned int cpu);
int hv_common_cpu_die(unsigned int cpu);
void hv_identify_partition_type(void);
+u64 mshv_pid_to_partid(pid_t tgid);
/**
* hv_cpu_number_to_vp_number() - Map CPU to VP.
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:19 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Passthru exposes insufficient memory hypercall failure in the current map
device interrupt hypercall. In case of such a failure, we must deposit
more memory and redo the hypercall. Add support for that. Deposit memory
needs partition id, make that a parameter to the map interrupt function.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
arch/x86/hyperv/irqdomain.c | 38 +++++++++++++++++++++++++++++++------
1 file changed, 32 insertions(+), 6 deletions(-)
diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index f6b61483b3b8..ccbe5848a28f 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -13,8 +13,9 @@
#include <linux/irqchip/irq-msi-lib.h>
#include <asm/mshyperv.h>
-static int hv_map_interrupt(union hv_device_id hv_devid, bool level,
- int cpu, int vector, struct hv_interrupt_entry *ret_entry)
+static u64 hv_map_interrupt_hcall(u64 ptid, union hv_device_id hv_devid,
+ bool level, int cpu, int vector,
+ struct hv_interrupt_entry *ret_entry)
{
struct hv_input_map_device_interrupt *input;
struct hv_output_map_device_interrupt *output;
@@ -30,8 +31,10 @@ static int hv_map_interrupt(union hv_device_id hv_devid, bool level,
intr_desc = &input->interrupt_descriptor;
memset(input, 0, sizeof(*input));
- input->partition_id = hv_current_partition_id;
+
+ input->partition_id = ptid;
input->device_id = hv_devid.as_uint64;
+
intr_desc->interrupt_type = HV_X64_INTERRUPT_TYPE_FIXED;
intr_desc->vector_count = 1;
intr_desc->target.vector = vector;
@@ -64,6 +67,28 @@ static int hv_map_interrupt(union hv_device_id hv_devid, bool level,
local_irq_restore(flags);
+ return status;
+}
+
+static int hv_map_interrupt(u64 ptid, union hv_device_id device_id, bool level,
+ int cpu, int vector,
+ struct hv_interrupt_entry *ret_entry)
+{
+ u64 status;
+ int rc, deposit_pgs = 16; /* don't loop forever */
+
+ while (deposit_pgs--) {
+ status = hv_map_interrupt_hcall(ptid, device_id, level, cpu,
+ vector, ret_entry);
+
+ if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY)
+ break;
+
+ rc = hv_call_deposit_pages(NUMA_NO_NODE, ptid, 1);
+ if (rc)
+ break;
+ };
+
if (!hv_result_success(status))
hv_status_err(status, "\n");
@@ -199,8 +224,8 @@ int hv_map_msi_interrupt(struct irq_data *data,
hv_devid = hv_build_devid_type_pci(pdev);
cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
- return hv_map_interrupt(hv_devid, false, cpu, cfg->vector,
- out_entry ? out_entry : &dummy);
+ return hv_map_interrupt(hv_current_partition_id, hv_devid, false, cpu,
+ cfg->vector, out_entry ? out_entry : &dummy);
}
EXPORT_SYMBOL_GPL(hv_map_msi_interrupt);
@@ -422,6 +447,7 @@ int hv_map_ioapic_interrupt(int ioapic_id, bool level, int cpu, int vector,
hv_devid.device_type = HV_DEVICE_TYPE_IOAPIC;
hv_devid.ioapic.ioapic_id = (u8)ioapic_id;
- return hv_map_interrupt(hv_devid, level, cpu, vector, entry);
+ return hv_map_interrupt(hv_current_partition_id, hv_devid, level, cpu,
+ vector, entry);
}
EXPORT_SYMBOL_GPL(hv_map_ioapic_interrupt);
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:18 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Main change here is to rename hv_compose_msi_msg to
hv_vmbus_compose_msi_msg as we introduce hv_compose_msi_msg in upcoming
patches that builds MSI messages for both VMBus and non-VMBus cases. VMBus
is not used on baremetal root partition for example. While at it, replace
spaces with tabs and fix some formatting involving excessive line wraps.
There is no functional change.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
drivers/pci/controller/pci-hyperv.c | 95 +++++++++++++++--------------
1 file changed, 48 insertions(+), 47 deletions(-)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 1e237d3538f9..8bc6a38c9b5a 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -30,7 +30,7 @@
* function's configuration space is zero.
*
* The rest of this driver mostly maps PCI concepts onto underlying Hyper-V
- * facilities. For instance, the configuration space of a function exposed
+ * facilities. For instance, the configuration space of a function exposed
* by Hyper-V is mapped into a single page of memory space, and the
* read and write handlers for config space must be aware of this mechanism.
* Similarly, device setup and teardown involves messages sent to and from
@@ -109,33 +109,33 @@ enum pci_message_type {
/*
* Version 1.1
*/
- PCI_MESSAGE_BASE = 0x42490000,
- PCI_BUS_RELATIONS = PCI_MESSAGE_BASE + 0,
- PCI_QUERY_BUS_RELATIONS = PCI_MESSAGE_BASE + 1,
- PCI_POWER_STATE_CHANGE = PCI_MESSAGE_BASE + 4,
+ PCI_MESSAGE_BASE = 0x42490000,
+ PCI_BUS_RELATIONS = PCI_MESSAGE_BASE + 0,
+ PCI_QUERY_BUS_RELATIONS = PCI_MESSAGE_BASE + 1,
+ PCI_POWER_STATE_CHANGE = PCI_MESSAGE_BASE + 4,
PCI_QUERY_RESOURCE_REQUIREMENTS = PCI_MESSAGE_BASE + 5,
- PCI_QUERY_RESOURCE_RESOURCES = PCI_MESSAGE_BASE + 6,
- PCI_BUS_D0ENTRY = PCI_MESSAGE_BASE + 7,
- PCI_BUS_D0EXIT = PCI_MESSAGE_BASE + 8,
- PCI_READ_BLOCK = PCI_MESSAGE_BASE + 9,
- PCI_WRITE_BLOCK = PCI_MESSAGE_BASE + 0xA,
- PCI_EJECT = PCI_MESSAGE_BASE + 0xB,
- PCI_QUERY_STOP = PCI_MESSAGE_BASE + 0xC,
- PCI_REENABLE = PCI_MESSAGE_BASE + 0xD,
- PCI_QUERY_STOP_FAILED = PCI_MESSAGE_BASE + 0xE,
- PCI_EJECTION_COMPLETE = PCI_MESSAGE_BASE + 0xF,
- PCI_RESOURCES_ASSIGNED = PCI_MESSAGE_BASE + 0x10,
- PCI_RESOURCES_RELEASED = PCI_MESSAGE_BASE + 0x11,
- PCI_INVALIDATE_BLOCK = PCI_MESSAGE_BASE + 0x12,
- PCI_QUERY_PROTOCOL_VERSION = PCI_MESSAGE_BASE + 0x13,
- PCI_CREATE_INTERRUPT_MESSAGE = PCI_MESSAGE_BASE + 0x14,
- PCI_DELETE_INTERRUPT_MESSAGE = PCI_MESSAGE_BASE + 0x15,
+ PCI_QUERY_RESOURCE_RESOURCES = PCI_MESSAGE_BASE + 6,
+ PCI_BUS_D0ENTRY = PCI_MESSAGE_BASE + 7,
+ PCI_BUS_D0EXIT = PCI_MESSAGE_BASE + 8,
+ PCI_READ_BLOCK = PCI_MESSAGE_BASE + 9,
+ PCI_WRITE_BLOCK = PCI_MESSAGE_BASE + 0xA,
+ PCI_EJECT = PCI_MESSAGE_BASE + 0xB,
+ PCI_QUERY_STOP = PCI_MESSAGE_BASE + 0xC,
+ PCI_REENABLE = PCI_MESSAGE_BASE + 0xD,
+ PCI_QUERY_STOP_FAILED = PCI_MESSAGE_BASE + 0xE,
+ PCI_EJECTION_COMPLETE = PCI_MESSAGE_BASE + 0xF,
+ PCI_RESOURCES_ASSIGNED = PCI_MESSAGE_BASE + 0x10,
+ PCI_RESOURCES_RELEASED = PCI_MESSAGE_BASE + 0x11,
+ PCI_INVALIDATE_BLOCK = PCI_MESSAGE_BASE + 0x12,
+ PCI_QUERY_PROTOCOL_VERSION = PCI_MESSAGE_BASE + 0x13,
+ PCI_CREATE_INTERRUPT_MESSAGE = PCI_MESSAGE_BASE + 0x14,
+ PCI_DELETE_INTERRUPT_MESSAGE = PCI_MESSAGE_BASE + 0x15,
PCI_RESOURCES_ASSIGNED2 = PCI_MESSAGE_BASE + 0x16,
PCI_CREATE_INTERRUPT_MESSAGE2 = PCI_MESSAGE_BASE + 0x17,
PCI_DELETE_INTERRUPT_MESSAGE2 = PCI_MESSAGE_BASE + 0x18, /* unused */
PCI_BUS_RELATIONS2 = PCI_MESSAGE_BASE + 0x19,
- PCI_RESOURCES_ASSIGNED3 = PCI_MESSAGE_BASE + 0x1A,
- PCI_CREATE_INTERRUPT_MESSAGE3 = PCI_MESSAGE_BASE + 0x1B,
+ PCI_RESOURCES_ASSIGNED3 = PCI_MESSAGE_BASE + 0x1A,
+ PCI_CREATE_INTERRUPT_MESSAGE3 = PCI_MESSAGE_BASE + 0x1B,
PCI_MESSAGE_MAXIMUM
};
@@ -1775,20 +1775,21 @@ static u32 hv_compose_msi_req_v1(
* via the HVCALL_RETARGET_INTERRUPT hypercall. But the choice of dummy vCPU is
* not irrelevant because Hyper-V chooses the physical CPU to handle the
* interrupts based on the vCPU specified in message sent to the vPCI VSP in
- * hv_compose_msi_msg(). Hyper-V's choice of pCPU is not visible to the guest,
- * but assigning too many vPCI device interrupts to the same pCPU can cause a
- * performance bottleneck. So we spread out the dummy vCPUs to influence Hyper-V
- * to spread out the pCPUs that it selects.
+ * hv_vmbus_compose_msi_msg(). Hyper-V's choice of pCPU is not visible to the
+ * guest, but assigning too many vPCI device interrupts to the same pCPU can
+ * cause a performance bottleneck. So we spread out the dummy vCPUs to influence
+ * Hyper-V to spread out the pCPUs that it selects.
*
* For the single-MSI and MSI-X cases, it's OK for hv_compose_msi_req_get_cpu()
* to always return the same dummy vCPU, because a second call to
- * hv_compose_msi_msg() contains the "real" vCPU, causing Hyper-V to choose a
- * new pCPU for the interrupt. But for the multi-MSI case, the second call to
- * hv_compose_msi_msg() exits without sending a message to the vPCI VSP, so the
- * original dummy vCPU is used. This dummy vCPU must be round-robin'ed so that
- * the pCPUs are spread out. All interrupts for a multi-MSI device end up using
- * the same pCPU, even though the vCPUs will be spread out by later calls
- * to hv_irq_unmask(), but that is the best we can do now.
+ * hv_vmbus_compose_msi_msg() contains the "real" vCPU, causing Hyper-V to
+ * choose a new pCPU for the interrupt. But for the multi-MSI case, the second
+ * call to hv_vmbus_compose_msi_msg() exits without sending a message to the
+ * vPCI VSP, so the original dummy vCPU is used. This dummy vCPU must be
+ * round-robin'ed so that the pCPUs are spread out. All interrupts for a
+ * multi-MSI device end up using the same pCPU, even though the vCPUs will be
+ * spread out by later calls to hv_irq_unmask(), but that is the best we can do
+ * now.
*
* With Hyper-V in Nov 2022, the HVCALL_RETARGET_INTERRUPT hypercall does *not*
* cause Hyper-V to reselect the pCPU based on the specified vCPU. Such an
@@ -1863,7 +1864,7 @@ static u32 hv_compose_msi_req_v3(
}
/**
- * hv_compose_msi_msg() - Supplies a valid MSI address/data
+ * hv_vmbus_compose_msi_msg() - Supplies a valid MSI address/data
* @data: Everything about this MSI
* @msg: Buffer that is filled in by this function
*
@@ -1873,7 +1874,7 @@ static u32 hv_compose_msi_req_v3(
* response supplies a data value and address to which that data
* should be written to trigger that interrupt.
*/
-static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
+static void hv_vmbus_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
struct hv_pcibus_device *hbus;
struct vmbus_channel *channel;
@@ -1955,7 +1956,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
return;
}
/*
- * The vector we select here is a dummy value. The correct
+ * The vector we select here is a dummy value. The correct
* value gets sent to the hypervisor in unmask(). This needs
* to be aligned with the count, and also not zero. Multi-msi
* is powers of 2 up to 32, so 32 will always work here.
@@ -2047,7 +2048,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
/*
* Make sure that the ring buffer data structure doesn't get
- * freed while we dereference the ring buffer pointer. Test
+ * freed while we dereference the ring buffer pointer. Test
* for the channel's onchannel_callback being NULL within a
* sched_lock critical section. See also the inline comments
* in vmbus_reset_channel_cb().
@@ -2147,7 +2148,7 @@ static const struct msi_parent_ops hv_pcie_msi_parent_ops = {
/* HW Interrupt Chip Descriptor */
static struct irq_chip hv_msi_irq_chip = {
.name = "Hyper-V PCIe MSI",
- .irq_compose_msi_msg = hv_compose_msi_msg,
+ .irq_compose_msi_msg = hv_vmbus_compose_msi_msg,
.irq_set_affinity = irq_chip_set_affinity_parent,
.irq_ack = irq_chip_ack_parent,
.irq_eoi = irq_chip_eoi_parent,
@@ -2159,8 +2160,8 @@ static int hv_pcie_domain_alloc(struct irq_domain *d, unsigned int virq, unsigne
void *arg)
{
/*
- * TODO: Allocating and populating struct tran_int_desc in hv_compose_msi_msg()
- * should be moved here.
+ * TODO: Allocating and populating struct tran_int_desc in
+ * hv_vmbus_compose_msi_msg() should be moved here.
*/
int ret;
@@ -2227,7 +2228,7 @@ static int hv_pcie_init_irq_domain(struct hv_pcibus_device *hbus)
/**
* get_bar_size() - Get the address space consumed by a BAR
* @bar_val: Value that a BAR returned after -1 was written
- * to it.
+ * to it.
*
* This function returns the size of the BAR, rounded up to 1
* page. It has to be rounded up because the hypervisor's page
@@ -2573,7 +2574,7 @@ static void q_resource_requirements(void *context, struct pci_response *resp,
* new_pcichild_device() - Create a new child device
* @hbus: The internal struct tracking this root PCI bus.
* @desc: The information supplied so far from the host
- * about the device.
+ * about the device.
*
* This function creates the tracking structure for a new child
* device and kicks off the process of figuring out what it is.
@@ -3100,7 +3101,7 @@ static void hv_pci_onchannelcallback(void *context)
* sure that the packet pointer is still valid during the call:
* here 'valid' means that there's a task still waiting for the
* completion, and that the packet data is still on the waiting
- * task's stack. Cf. hv_compose_msi_msg().
+ * task's stack. Cf. hv_vmbus_compose_msi_msg().
*/
comp_packet->completion_func(comp_packet->compl_ctxt,
response,
@@ -3417,7 +3418,7 @@ static int hv_allocate_config_window(struct hv_pcibus_device *hbus)
* vmbus_allocate_mmio() gets used for allocating both device endpoint
* resource claims (those which cannot be overlapped) and the ranges
* which are valid for the children of this bus, which are intended
- * to be overlapped by those children. Set the flag on this claim
+ * to be overlapped by those children. Set the flag on this claim
* meaning that this region can't be overlapped.
*/
@@ -4066,7 +4067,7 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
irq_data = irq_get_irq_data(entry->irq);
if (WARN_ON_ONCE(!irq_data))
return -EINVAL;
- hv_compose_msi_msg(irq_data, &entry->msg);
+ hv_vmbus_compose_msi_msg(irq_data, &entry->msg);
}
return 0;
}
@@ -4074,7 +4075,7 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
/*
* Upon resume, pci_restore_msi_state() -> ... -> __pci_write_msi_msg()
* directly writes the MSI/MSI-X registers via MMIO, but since Hyper-V
- * doesn't trap and emulate the MMIO accesses, here hv_compose_msi_msg()
+ * doesn't trap and emulate the MMIO accesses, here hv_vmbus_compose_msi_msg()
* must be used to ask Hyper-V to re-create the IOMMU Interrupt Remapping
* Table entries.
*/
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:23 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Add ioctl support for creating MSHV devices for a paritition. At
present only VFIO device types are supported, but more could be
added. At a high level, a partition ioctl to create device verifies
it is of type VFIO and does some setup for bridge code in mshv_vfio.c.
Adapted from KVM device ioctls.
Credits: Original author: Wei Liu <wei.liu@kernel.org>
NB: Slightly modified from the original version.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
drivers/hv/mshv_root_main.c | 126 ++++++++++++++++++++++++++++++++++++
1 file changed, 126 insertions(+)
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 83c7bad269a0..27313419828d 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1551,6 +1551,129 @@ mshv_partition_ioctl_initialize(struct mshv_partition *partition)
return ret;
}
+static long mshv_device_attr_ioctl(struct mshv_device *mshv_dev, int cmd,
+ ulong uarg)
+{
+ struct mshv_device_attr attr;
+ const struct mshv_device_ops *devops = mshv_dev->device_ops;
+
+ if (copy_from_user(&attr, (void __user *)uarg, sizeof(attr)))
+ return -EFAULT;
+
+ switch (cmd) {
+ case MSHV_SET_DEVICE_ATTR:
+ if (devops->device_set_attr)
+ return devops->device_set_attr(mshv_dev, &attr);
+ break;
+ case MSHV_HAS_DEVICE_ATTR:
+ if (devops->device_has_attr)
+ return devops->device_has_attr(mshv_dev, &attr);
+ break;
+ }
+
+ return -EPERM;
+}
+
+static long mshv_device_fop_ioctl(struct file *filp, unsigned int cmd,
+ ulong uarg)
+{
+ struct mshv_device *mshv_dev = filp->private_data;
+
+ switch (cmd) {
+ case MSHV_SET_DEVICE_ATTR:
+ case MSHV_HAS_DEVICE_ATTR:
+ return mshv_device_attr_ioctl(mshv_dev, cmd, uarg);
+ }
+
+ return -ENOTTY;
+}
+
+static int mshv_device_fop_release(struct inode *inode, struct file *filp)
+{
+ struct mshv_device *mshv_dev = filp->private_data;
+ struct mshv_partition *partition = mshv_dev->device_pt;
+
+ if (mshv_dev->device_ops->device_release) {
+ mutex_lock(&partition->pt_mutex);
+ hlist_del(&mshv_dev->device_ptnode);
+ mshv_dev->device_ops->device_release(mshv_dev);
+ mutex_unlock(&partition->pt_mutex);
+ }
+
+ mshv_partition_put(partition);
+ return 0;
+}
+
+static const struct file_operations mshv_device_fops = {
+ .owner = THIS_MODULE,
+ .unlocked_ioctl = mshv_device_fop_ioctl,
+ .release = mshv_device_fop_release,
+};
+
+long mshv_partition_ioctl_create_device(struct mshv_partition *partition,
+ void __user *uarg)
+{
+ long rc;
+ struct mshv_create_device devargk;
+ struct mshv_device *mshv_dev;
+ const struct mshv_device_ops *vfio_ops;
+ int type;
+
+ if (copy_from_user(&devargk, uarg, sizeof(devargk))) {
+ rc = -EFAULT;
+ goto out;
+ }
+
+ /* At present, only VFIO is supported */
+ if (devargk.type != MSHV_DEV_TYPE_VFIO) {
+ rc = -ENODEV;
+ goto out;
+ }
+
+ if (devargk.flags & MSHV_CREATE_DEVICE_TEST) {
+ rc = 0;
+ goto out;
+ }
+
+ mshv_dev = kzalloc(sizeof(*mshv_dev), GFP_KERNEL_ACCOUNT);
+ if (mshv_dev == NULL) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ vfio_ops = &mshv_vfio_device_ops;
+ mshv_dev->device_ops = vfio_ops;
+ mshv_dev->device_pt = partition;
+
+ rc = vfio_ops->device_create(mshv_dev, type);
+ if (rc < 0) {
+ kfree(mshv_dev);
+ goto out;
+ }
+
+ hlist_add_head(&mshv_dev->device_ptnode, &partition->pt_devices);
+
+ mshv_partition_get(partition);
+ rc = anon_inode_getfd(vfio_ops->device_name, &mshv_device_fops,
+ mshv_dev, O_RDWR | O_CLOEXEC);
+ if (rc < 0) {
+ mshv_partition_put(partition);
+ hlist_del(&mshv_dev->device_ptnode);
+ vfio_ops->device_release(mshv_dev);
+ goto out;
+ }
+
+ devargk.fd = rc;
+ rc = 0;
+
+ if (copy_to_user(uarg, &devargk, sizeof(devargk))) {
+ rc = -EFAULT;
+ goto out;
+ }
+out:
+ return rc;
+}
+
static long
mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
{
@@ -1587,6 +1710,9 @@ mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
case MSHV_ROOT_HVCALL:
ret = mshv_ioctl_passthru_hvcall(partition, true, uarg);
break;
+ case MSHV_CREATE_DEVICE:
+ ret = mshv_partition_ioctl_create_device(partition, uarg);
+ break;
default:
ret = -ENOTTY;
}
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:22 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Add data structs needed by the subsequent patch that introduces a new
module to implement VFIO-MSHV pseudo device.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
drivers/hv/mshv_root.h | 23 +++++++++++++++++++++++
include/uapi/linux/mshv.h | 31 +++++++++++++++++++++++++++++++
2 files changed, 54 insertions(+)
diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index c3753b009fd8..42e1da1d545b 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -220,6 +220,29 @@ struct port_table_info {
};
};
+struct mshv_device {
+ const struct mshv_device_ops *device_ops;
+ struct mshv_partition *device_pt;
+ void *device_private;
+ struct hlist_node device_ptnode;
+};
+
+struct mshv_device_ops {
+ const char *device_name;
+ long (*device_create)(struct mshv_device *dev, u32 type);
+ void (*device_release)(struct mshv_device *dev);
+ long (*device_set_attr)(struct mshv_device *dev,
+ struct mshv_device_attr *attr);
+ long (*device_has_attr)(struct mshv_device *dev,
+ struct mshv_device_attr *attr);
+};
+
+extern struct mshv_device_ops mshv_vfio_device_ops;
+int mshv_vfio_ops_init(void);
+void mshv_vfio_ops_exit(void);
+long mshv_partition_ioctl_create_device(struct mshv_partition *partition,
+ void __user *user_args);
+
int mshv_update_routing_table(struct mshv_partition *partition,
const struct mshv_user_irq_entry *entries,
unsigned int numents);
diff --git a/include/uapi/linux/mshv.h b/include/uapi/linux/mshv.h
index dee3ece28ce5..b7b10f9e2896 100644
--- a/include/uapi/linux/mshv.h
+++ b/include/uapi/linux/mshv.h
@@ -252,6 +252,7 @@ struct mshv_root_hvcall {
#define MSHV_GET_GPAP_ACCESS_BITMAP _IOWR(MSHV_IOCTL, 0x06, struct mshv_gpap_access_bitmap)
/* Generic hypercall */
#define MSHV_ROOT_HVCALL _IOWR(MSHV_IOCTL, 0x07, struct mshv_root_hvcall)
+#define MSHV_CREATE_DEVICE _IOWR(MSHV_IOCTL, 0x08, struct mshv_create_device)
/*
********************************
@@ -402,4 +403,34 @@ struct mshv_sint_mask {
/* hv_hvcall device */
#define MSHV_HVCALL_SETUP _IOW(MSHV_IOCTL, 0x1E, struct mshv_vtl_hvcall_setup)
#define MSHV_HVCALL _IOWR(MSHV_IOCTL, 0x1F, struct mshv_vtl_hvcall)
+
+/* device passhthru */
+#define MSHV_CREATE_DEVICE_TEST 1
+
+enum {
+ MSHV_DEV_TYPE_VFIO,
+ MSHV_DEV_TYPE_MAX,
+};
+
+struct mshv_create_device {
+ __u32 type; /* in: MSHV_DEV_TYPE_xxx */
+ __u32 fd; /* out: device handle */
+ __u32 flags; /* in: MSHV_CREATE_DEVICE_xxx */
+};
+
+#define MSHV_DEV_VFIO_FILE 1
+#define MSHV_DEV_VFIO_FILE_ADD 1
+#define MSHV_DEV_VFIO_FILE_DEL 2
+
+struct mshv_device_attr {
+ __u32 flags; /* no flags currently defined */
+ __u32 group; /* device-defined */
+ __u64 attr; /* group-defined */
+ __u64 addr; /* userspace address of attr data */
+};
+
+/* Device fds created with MSHV_CREATE_DEVICE */
+#define MSHV_SET_DEVICE_ATTR _IOW(MSHV_IOCTL, 0x00, struct mshv_device_attr)
+#define MSHV_HAS_DEVICE_ATTR _IOW(MSHV_IOCTL, 0x01, struct mshv_device_attr)
+
#endif
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:20 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Make cosmetic changes:
o Rename struct pci_dev *dev to *pdev since there are cases of
struct device *dev in the file and all over the kernel
o Rename hv_build_pci_dev_id to hv_build_devid_type_pci in anticipation
of building different types of device ids
o Fix checkpatch.pl issues with return and extraneous printk
o Replace spaces with tabs
o Rename struct hv_devid *xxx to struct hv_devid *hv_devid given code
paths involve many types of device ids
o Fix indentation in a large if block by using goto.
There are no functional changes.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
arch/x86/hyperv/irqdomain.c | 197 +++++++++++++++++++-----------------
1 file changed, 103 insertions(+), 94 deletions(-)
diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index c3ba12b1bc07..f6b61483b3b8 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -1,5 +1,4 @@
// SPDX-License-Identifier: GPL-2.0
-
/*
* Irqdomain for Linux to run as the root partition on Microsoft Hypervisor.
*
@@ -14,8 +13,8 @@
#include <linux/irqchip/irq-msi-lib.h>
#include <asm/mshyperv.h>
-static int hv_map_interrupt(union hv_device_id device_id, bool level,
- int cpu, int vector, struct hv_interrupt_entry *entry)
+static int hv_map_interrupt(union hv_device_id hv_devid, bool level,
+ int cpu, int vector, struct hv_interrupt_entry *ret_entry)
{
struct hv_input_map_device_interrupt *input;
struct hv_output_map_device_interrupt *output;
@@ -32,7 +31,7 @@ static int hv_map_interrupt(union hv_device_id device_id, bool level,
intr_desc = &input->interrupt_descriptor;
memset(input, 0, sizeof(*input));
input->partition_id = hv_current_partition_id;
- input->device_id = device_id.as_uint64;
+ input->device_id = hv_devid.as_uint64;
intr_desc->interrupt_type = HV_X64_INTERRUPT_TYPE_FIXED;
intr_desc->vector_count = 1;
intr_desc->target.vector = vector;
@@ -44,7 +43,7 @@ static int hv_map_interrupt(union hv_device_id device_id, bool level,
intr_desc->target.vp_set.valid_bank_mask = 0;
intr_desc->target.vp_set.format = HV_GENERIC_SET_SPARSE_4K;
- nr_bank = cpumask_to_vpset(&(intr_desc->target.vp_set), cpumask_of(cpu));
+ nr_bank = cpumask_to_vpset(&intr_desc->target.vp_set, cpumask_of(cpu));
if (nr_bank < 0) {
local_irq_restore(flags);
pr_err("%s: unable to generate VP set\n", __func__);
@@ -61,7 +60,7 @@ static int hv_map_interrupt(union hv_device_id device_id, bool level,
status = hv_do_rep_hypercall(HVCALL_MAP_DEVICE_INTERRUPT, 0, var_size,
input, output);
- *entry = output->interrupt_entry;
+ *ret_entry = output->interrupt_entry;
local_irq_restore(flags);
@@ -71,21 +70,19 @@ static int hv_map_interrupt(union hv_device_id device_id, bool level,
return hv_result_to_errno(status);
}
-static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry *old_entry)
+static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry *irq_entry)
{
unsigned long flags;
struct hv_input_unmap_device_interrupt *input;
- struct hv_interrupt_entry *intr_entry;
u64 status;
local_irq_save(flags);
input = *this_cpu_ptr(hyperv_pcpu_input_arg);
memset(input, 0, sizeof(*input));
- intr_entry = &input->interrupt_entry;
input->partition_id = hv_current_partition_id;
input->device_id = id;
- *intr_entry = *old_entry;
+ input->interrupt_entry = *irq_entry;
status = hv_do_hypercall(HVCALL_UNMAP_DEVICE_INTERRUPT, input, NULL);
local_irq_restore(flags);
@@ -115,67 +112,71 @@ static int get_rid_cb(struct pci_dev *pdev, u16 alias, void *data)
return 0;
}
-static union hv_device_id hv_build_pci_dev_id(struct pci_dev *dev)
+static union hv_device_id hv_build_devid_type_pci(struct pci_dev *pdev)
{
- union hv_device_id dev_id;
+ int pos;
+ union hv_device_id hv_devid;
struct rid_data data = {
.bridge = NULL,
- .rid = PCI_DEVID(dev->bus->number, dev->devfn)
+ .rid = PCI_DEVID(pdev->bus->number, pdev->devfn)
};
- pci_for_each_dma_alias(dev, get_rid_cb, &data);
+ pci_for_each_dma_alias(pdev, get_rid_cb, &data);
- dev_id.as_uint64 = 0;
- dev_id.device_type = HV_DEVICE_TYPE_PCI;
- dev_id.pci.segment = pci_domain_nr(dev->bus);
+ hv_devid.as_uint64 = 0;
+ hv_devid.device_type = HV_DEVICE_TYPE_PCI;
+ hv_devid.pci.segment = pci_domain_nr(pdev->bus);
- dev_id.pci.bdf.bus = PCI_BUS_NUM(data.rid);
- dev_id.pci.bdf.device = PCI_SLOT(data.rid);
- dev_id.pci.bdf.function = PCI_FUNC(data.rid);
- dev_id.pci.source_shadow = HV_SOURCE_SHADOW_NONE;
+ hv_devid.pci.bdf.bus = PCI_BUS_NUM(data.rid);
+ hv_devid.pci.bdf.device = PCI_SLOT(data.rid);
+ hv_devid.pci.bdf.function = PCI_FUNC(data.rid);
+ hv_devid.pci.source_shadow = HV_SOURCE_SHADOW_NONE;
- if (data.bridge) {
- int pos;
+ if (data.bridge == NULL)
+ goto out;
- /*
- * Microsoft Hypervisor requires a bus range when the bridge is
- * running in PCI-X mode.
- *
- * To distinguish conventional vs PCI-X bridge, we can check
- * the bridge's PCI-X Secondary Status Register, Secondary Bus
- * Mode and Frequency bits. See PCI Express to PCI/PCI-X Bridge
- * Specification Revision 1.0 5.2.2.1.3.
- *
- * Value zero means it is in conventional mode, otherwise it is
- * in PCI-X mode.
- */
+ /*
+ * Microsoft Hypervisor requires a bus range when the bridge is
+ * running in PCI-X mode.
+ *
+ * To distinguish conventional vs PCI-X bridge, we can check
+ * the bridge's PCI-X Secondary Status Register, Secondary Bus
+ * Mode and Frequency bits. See PCI Express to PCI/PCI-X Bridge
+ * Specification Revision 1.0 5.2.2.1.3.
+ *
+ * Value zero means it is in conventional mode, otherwise it is
+ * in PCI-X mode.
+ */
- pos = pci_find_capability(data.bridge, PCI_CAP_ID_PCIX);
- if (pos) {
- u16 status;
+ pos = pci_find_capability(data.bridge, PCI_CAP_ID_PCIX);
+ if (pos) {
+ u16 status;
- pci_read_config_word(data.bridge, pos +
- PCI_X_BRIDGE_SSTATUS, &status);
+ pci_read_config_word(data.bridge, pos + PCI_X_BRIDGE_SSTATUS,
+ &status);
- if (status & PCI_X_SSTATUS_FREQ) {
- /* Non-zero, PCI-X mode */
- u8 sec_bus, sub_bus;
+ if (status & PCI_X_SSTATUS_FREQ) {
+ /* Non-zero, PCI-X mode */
+ u8 sec_bus, sub_bus;
- dev_id.pci.source_shadow = HV_SOURCE_SHADOW_BRIDGE_BUS_RANGE;
+ hv_devid.pci.source_shadow =
+ HV_SOURCE_SHADOW_BRIDGE_BUS_RANGE;
- pci_read_config_byte(data.bridge, PCI_SECONDARY_BUS, &sec_bus);
- dev_id.pci.shadow_bus_range.secondary_bus = sec_bus;
- pci_read_config_byte(data.bridge, PCI_SUBORDINATE_BUS, &sub_bus);
- dev_id.pci.shadow_bus_range.subordinate_bus = sub_bus;
- }
+ pci_read_config_byte(data.bridge, PCI_SECONDARY_BUS,
+ &sec_bus);
+ hv_devid.pci.shadow_bus_range.secondary_bus = sec_bus;
+ pci_read_config_byte(data.bridge, PCI_SUBORDINATE_BUS,
+ &sub_bus);
+ hv_devid.pci.shadow_bus_range.subordinate_bus = sub_bus;
}
}
- return dev_id;
+out:
+ return hv_devid;
}
-/**
- * hv_map_msi_interrupt() - "Map" the MSI IRQ in the hypervisor.
+/*
+ * hv_map_msi_interrupt() - Map the MSI IRQ in the hypervisor.
* @data: Describes the IRQ
* @out_entry: Hypervisor (MSI) interrupt entry (can be NULL)
*
@@ -188,22 +189,23 @@ int hv_map_msi_interrupt(struct irq_data *data,
{
struct irq_cfg *cfg = irqd_cfg(data);
struct hv_interrupt_entry dummy;
- union hv_device_id device_id;
+ union hv_device_id hv_devid;
struct msi_desc *msidesc;
- struct pci_dev *dev;
+ struct pci_dev *pdev;
int cpu;
msidesc = irq_data_get_msi_desc(data);
- dev = msi_desc_to_pci_dev(msidesc);
- device_id = hv_build_pci_dev_id(dev);
+ pdev = msi_desc_to_pci_dev(msidesc);
+ hv_devid = hv_build_devid_type_pci(pdev);
cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
- return hv_map_interrupt(device_id, false, cpu, cfg->vector,
+ return hv_map_interrupt(hv_devid, false, cpu, cfg->vector,
out_entry ? out_entry : &dummy);
}
EXPORT_SYMBOL_GPL(hv_map_msi_interrupt);
-static inline void entry_to_msi_msg(struct hv_interrupt_entry *entry, struct msi_msg *msg)
+static void entry_to_msi_msg(struct hv_interrupt_entry *entry,
+ struct msi_msg *msg)
{
/* High address is always 0 */
msg->address_hi = 0;
@@ -211,17 +213,19 @@ static inline void entry_to_msi_msg(struct hv_interrupt_entry *entry, struct msi
msg->data = entry->msi_entry.data.as_uint32;
}
-static int hv_unmap_msi_interrupt(struct pci_dev *dev, struct hv_interrupt_entry *old_entry);
+static int hv_unmap_msi_interrupt(struct pci_dev *pdev,
+ struct hv_interrupt_entry *irq_entry);
+
static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
struct hv_interrupt_entry *stored_entry;
struct irq_cfg *cfg = irqd_cfg(data);
struct msi_desc *msidesc;
- struct pci_dev *dev;
+ struct pci_dev *pdev;
int ret;
msidesc = irq_data_get_msi_desc(data);
- dev = msi_desc_to_pci_dev(msidesc);
+ pdev = msi_desc_to_pci_dev(msidesc);
if (!cfg) {
pr_debug("%s: cfg is NULL", __func__);
@@ -240,7 +244,7 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
stored_entry = data->chip_data;
data->chip_data = NULL;
- ret = hv_unmap_msi_interrupt(dev, stored_entry);
+ ret = hv_unmap_msi_interrupt(pdev, stored_entry);
kfree(stored_entry);
@@ -249,10 +253,8 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
}
stored_entry = kzalloc(sizeof(*stored_entry), GFP_ATOMIC);
- if (!stored_entry) {
- pr_debug("%s: failed to allocate chip data\n", __func__);
+ if (!stored_entry)
return;
- }
ret = hv_map_msi_interrupt(data, stored_entry);
if (ret) {
@@ -262,18 +264,21 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
data->chip_data = stored_entry;
entry_to_msi_msg(data->chip_data, msg);
-
- return;
}
-static int hv_unmap_msi_interrupt(struct pci_dev *dev, struct hv_interrupt_entry *old_entry)
+static int hv_unmap_msi_interrupt(struct pci_dev *pdev,
+ struct hv_interrupt_entry *irq_entry)
{
- return hv_unmap_interrupt(hv_build_pci_dev_id(dev).as_uint64, old_entry);
+ union hv_device_id hv_devid;
+
+ hv_devid = hv_build_devid_type_pci(pdev);
+ return hv_unmap_interrupt(hv_devid.as_uint64, irq_entry);
}
-static void hv_teardown_msi_irq(struct pci_dev *dev, struct irq_data *irqd)
+/* NB: during map, hv_interrupt_entry is saved via data->chip_data */
+static void hv_teardown_msi_irq(struct pci_dev *pdev, struct irq_data *irqd)
{
- struct hv_interrupt_entry old_entry;
+ struct hv_interrupt_entry irq_entry;
struct msi_msg msg;
if (!irqd->chip_data) {
@@ -281,13 +286,13 @@ static void hv_teardown_msi_irq(struct pci_dev *dev, struct irq_data *irqd)
return;
}
- old_entry = *(struct hv_interrupt_entry *)irqd->chip_data;
- entry_to_msi_msg(&old_entry, &msg);
+ irq_entry = *(struct hv_interrupt_entry *)irqd->chip_data;
+ entry_to_msi_msg(&irq_entry, &msg);
kfree(irqd->chip_data);
irqd->chip_data = NULL;
- (void)hv_unmap_msi_interrupt(dev, &old_entry);
+ (void)hv_unmap_msi_interrupt(pdev, &irq_entry);
}
/*
@@ -302,7 +307,8 @@ static struct irq_chip hv_pci_msi_controller = {
};
static bool hv_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
- struct irq_domain *real_parent, struct msi_domain_info *info)
+ struct irq_domain *real_parent,
+ struct msi_domain_info *info)
{
struct irq_chip *chip = info->chip;
@@ -317,7 +323,8 @@ static bool hv_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
}
#define HV_MSI_FLAGS_SUPPORTED (MSI_GENERIC_FLAGS_MASK | MSI_FLAG_PCI_MSIX)
-#define HV_MSI_FLAGS_REQUIRED (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS)
+#define HV_MSI_FLAGS_REQUIRED (MSI_FLAG_USE_DEF_DOM_OPS | \
+ MSI_FLAG_USE_DEF_CHIP_OPS)
static struct msi_parent_ops hv_msi_parent_ops = {
.supported_flags = HV_MSI_FLAGS_SUPPORTED,
@@ -329,14 +336,13 @@ static struct msi_parent_ops hv_msi_parent_ops = {
.init_dev_msi_info = hv_init_dev_msi_info,
};
-static int hv_msi_domain_alloc(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs,
- void *arg)
+static int hv_msi_domain_alloc(struct irq_domain *d, unsigned int virq,
+ unsigned int nr_irqs, void *arg)
{
/*
- * TODO: The allocation bits of hv_irq_compose_msi_msg(), i.e. everything except
- * entry_to_msi_msg() should be in here.
+ * TODO: The allocation bits of hv_irq_compose_msi_msg(), i.e.
+ * everything except entry_to_msi_msg() should be in here.
*/
-
int ret;
ret = irq_domain_alloc_irqs_parent(d, virq, nr_irqs, arg);
@@ -344,13 +350,15 @@ static int hv_msi_domain_alloc(struct irq_domain *d, unsigned int virq, unsigned
return ret;
for (int i = 0; i < nr_irqs; ++i) {
- irq_domain_set_info(d, virq + i, 0, &hv_pci_msi_controller, NULL,
- handle_edge_irq, NULL, "edge");
+ irq_domain_set_info(d, virq + i, 0, &hv_pci_msi_controller,
+ NULL, handle_edge_irq, NULL, "edge");
}
+
return 0;
}
-static void hv_msi_domain_free(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs)
+static void hv_msi_domain_free(struct irq_domain *d, unsigned int virq,
+ unsigned int nr_irqs)
{
for (int i = 0; i < nr_irqs; ++i) {
struct irq_data *irqd = irq_domain_get_irq_data(d, virq);
@@ -362,6 +370,7 @@ static void hv_msi_domain_free(struct irq_domain *d, unsigned int virq, unsigned
hv_teardown_msi_irq(to_pci_dev(desc->dev), irqd);
}
+
irq_domain_free_irqs_top(d, virq, nr_irqs);
}
@@ -394,25 +403,25 @@ struct irq_domain * __init hv_create_pci_msi_domain(void)
int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry)
{
- union hv_device_id device_id;
+ union hv_device_id hv_devid;
- device_id.as_uint64 = 0;
- device_id.device_type = HV_DEVICE_TYPE_IOAPIC;
- device_id.ioapic.ioapic_id = (u8)ioapic_id;
+ hv_devid.as_uint64 = 0;
+ hv_devid.device_type = HV_DEVICE_TYPE_IOAPIC;
+ hv_devid.ioapic.ioapic_id = (u8)ioapic_id;
- return hv_unmap_interrupt(device_id.as_uint64, entry);
+ return hv_unmap_interrupt(hv_devid.as_uint64, entry);
}
EXPORT_SYMBOL_GPL(hv_unmap_ioapic_interrupt);
int hv_map_ioapic_interrupt(int ioapic_id, bool level, int cpu, int vector,
struct hv_interrupt_entry *entry)
{
- union hv_device_id device_id;
+ union hv_device_id hv_devid;
- device_id.as_uint64 = 0;
- device_id.device_type = HV_DEVICE_TYPE_IOAPIC;
- device_id.ioapic.ioapic_id = (u8)ioapic_id;
+ hv_devid.as_uint64 = 0;
+ hv_devid.device_type = HV_DEVICE_TYPE_IOAPIC;
+ hv_devid.ioapic.ioapic_id = (u8)ioapic_id;
- return hv_map_interrupt(device_id, level, cpu, vector, entry);
+ return hv_map_interrupt(hv_devid, level, cpu, vector, entry);
}
EXPORT_SYMBOL_GPL(hv_map_ioapic_interrupt);
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:17 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Add a new file to implement VFIO-MSHV bridge pseudo device. These
functions are called in the VFIO framework, and credits to kvm/vfio.c
as this file was adapted from it.
Original author: Wei Liu <wei.liu@kernel.org>
(Slightly modified from the original version).
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_vfio.c | 210 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 212 insertions(+), 1 deletion(-)
create mode 100644 drivers/hv/mshv_vfio.c
diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile
index a49f93c2d245..eae003c4cb8f 100644
--- a/drivers/hv/Makefile
+++ b/drivers/hv/Makefile
@@ -14,7 +14,8 @@ hv_vmbus-y := vmbus_drv.o \
hv_vmbus-$(CONFIG_HYPERV_TESTING) += hv_debugfs.o
hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_utils_transport.o
mshv_root-y := mshv_root_main.o mshv_synic.o mshv_eventfd.o mshv_irq.o \
- mshv_root_hv_call.o mshv_portid_table.o mshv_regions.o
+ mshv_root_hv_call.o mshv_portid_table.o mshv_regions.o \
+ mshv_vfio.o
mshv_vtl-y := mshv_vtl_main.o
# Code that must be built-in
diff --git a/drivers/hv/mshv_vfio.c b/drivers/hv/mshv_vfio.c
new file mode 100644
index 000000000000..6ea4d99a3bd2
--- /dev/null
+++ b/drivers/hv/mshv_vfio.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VFIO-MSHV bridge pseudo device
+ *
+ * Heavily inspired by the VFIO-KVM bridge pseudo device.
+ */
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/vfio.h>
+
+#include "mshv.h"
+#include "mshv_root.h"
+
+struct mshv_vfio_file {
+ struct list_head node;
+ struct file *file; /* list of struct mshv_vfio_file */
+};
+
+struct mshv_vfio {
+ struct list_head file_list;
+ struct mutex lock;
+};
+
+static bool mshv_vfio_file_is_valid(struct file *file)
+{
+ bool (*fn)(struct file *file);
+ bool ret;
+
+ fn = symbol_get(vfio_file_is_valid);
+ if (!fn)
+ return false;
+
+ ret = fn(file);
+
+ symbol_put(vfio_file_is_valid);
+
+ return ret;
+}
+
+static long mshv_vfio_file_add(struct mshv_device *mshvdev, unsigned int fd)
+{
+ struct mshv_vfio *mshv_vfio = mshvdev->device_private;
+ struct mshv_vfio_file *mvf;
+ struct file *filp;
+ long ret = 0;
+
+ filp = fget(fd);
+ if (!filp)
+ return -EBADF;
+
+ /* Ensure the FD is a vfio FD. */
+ if (!mshv_vfio_file_is_valid(filp)) {
+ ret = -EINVAL;
+ goto out_fput;
+ }
+
+ mutex_lock(&mshv_vfio->lock);
+
+ list_for_each_entry(mvf, &mshv_vfio->file_list, node) {
+ if (mvf->file == filp) {
+ ret = -EEXIST;
+ goto out_unlock;
+ }
+ }
+
+ mvf = kzalloc(sizeof(*mvf), GFP_KERNEL_ACCOUNT);
+ if (!mvf) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+
+ mvf->file = get_file(filp);
+ list_add_tail(&mvf->node, &mshv_vfio->file_list);
+
+out_unlock:
+ mutex_unlock(&mshv_vfio->lock);
+out_fput:
+ fput(filp);
+ return ret;
+}
+
+static long mshv_vfio_file_del(struct mshv_device *mshvdev, unsigned int fd)
+{
+ struct mshv_vfio *mshv_vfio = mshvdev->device_private;
+ struct mshv_vfio_file *mvf;
+ long ret;
+
+ CLASS(fd, f)(fd);
+
+ if (fd_empty(f))
+ return -EBADF;
+
+ ret = -ENOENT;
+ mutex_lock(&mshv_vfio->lock);
+
+ list_for_each_entry(mvf, &mshv_vfio->file_list, node) {
+ if (mvf->file != fd_file(f))
+ continue;
+
+ list_del(&mvf->node);
+ fput(mvf->file);
+ kfree(mvf);
+ ret = 0;
+ break;
+ }
+
+ mutex_unlock(&mshv_vfio->lock);
+ return ret;
+}
+
+static long mshv_vfio_set_file(struct mshv_device *mshvdev, long attr,
+ void __user *arg)
+{
+ int32_t __user *argp = arg;
+ int32_t fd;
+
+ switch (attr) {
+ case MSHV_DEV_VFIO_FILE_ADD:
+ if (get_user(fd, argp))
+ return -EFAULT;
+ return mshv_vfio_file_add(mshvdev, fd);
+
+ case MSHV_DEV_VFIO_FILE_DEL:
+ if (get_user(fd, argp))
+ return -EFAULT;
+ return mshv_vfio_file_del(mshvdev, fd);
+ }
+
+ return -ENXIO;
+}
+
+static long mshv_vfio_set_attr(struct mshv_device *mshvdev,
+ struct mshv_device_attr *attr)
+{
+ switch (attr->group) {
+ case MSHV_DEV_VFIO_FILE:
+ return mshv_vfio_set_file(mshvdev, attr->attr,
+ u64_to_user_ptr(attr->addr));
+ }
+
+ return -ENXIO;
+}
+
+static long mshv_vfio_has_attr(struct mshv_device *mshvdev,
+ struct mshv_device_attr *attr)
+{
+ switch (attr->group) {
+ case MSHV_DEV_VFIO_FILE:
+ switch (attr->attr) {
+ case MSHV_DEV_VFIO_FILE_ADD:
+ case MSHV_DEV_VFIO_FILE_DEL:
+ return 0;
+ }
+
+ break;
+ }
+
+ return -ENXIO;
+}
+
+static long mshv_vfio_create_device(struct mshv_device *mshvdev, u32 type)
+{
+ struct mshv_device *tmp;
+ struct mshv_vfio *mshv_vfio;
+
+ /* Only one VFIO "device" per VM */
+ hlist_for_each_entry(tmp, &mshvdev->device_pt->pt_devices,
+ device_ptnode)
+ if (tmp->device_ops == &mshv_vfio_device_ops)
+ return -EBUSY;
+
+ mshv_vfio = kzalloc(sizeof(*mshv_vfio), GFP_KERNEL_ACCOUNT);
+ if (mshv_vfio == NULL)
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&mshv_vfio->file_list);
+ mutex_init(&mshv_vfio->lock);
+
+ mshvdev->device_private = mshv_vfio;
+
+ return 0;
+}
+
+/* This is called from mshv_device_fop_release() */
+static void mshv_vfio_release_device(struct mshv_device *mshvdev)
+{
+ struct mshv_vfio *mv = mshvdev->device_private;
+ struct mshv_vfio_file *mvf, *tmp;
+
+ list_for_each_entry_safe(mvf, tmp, &mv->file_list, node) {
+ fput(mvf->file);
+ list_del(&mvf->node);
+ kfree(mvf);
+ }
+
+ kfree(mv);
+ kfree(mshvdev);
+}
+
+struct mshv_device_ops mshv_vfio_device_ops = {
+ .device_name = "mshv-vfio",
+ .device_create = mshv_vfio_create_device,
+ .device_release = mshv_vfio_release_device,
+ .device_set_attr = mshv_vfio_set_attr,
+ .device_has_attr = mshv_vfio_has_attr,
+};
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:21 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
As mentioned previously, a direct attached device must be referenced
via logical device id which is formed in the initial attach hypercall.
Interrupt mapping paths for direct attached devices are almost same,
except we must use logical device ids instead of the PCI device ids.
L1VH only supports direct attaches for passing thru devices to its guests,
and devices on L1VH are VMBus based. However, the interrupts are mapped
via the map interrupt hypercall and not the traditional method of VMBus
messages.
Partition id for the relevant hypercalls is tricky. This because a device
could be moving from root to guest and then back to the root. In case
of L1VH, it could be moving from system host to L1VH root to a guest,
then back to the L1VH root. So, it is carefully crafted by keeping
track of whether the call is on behalf of a VMM process, whether the
device is attached device (as opposed to mapped), and whether we are in
an L1VH root/parent. If VMM process, we assume it is on behalf of a
guest. Otherwise, the device is being attached or detached during boot
or shutdown of the privileged partition.
Lastly, a dummy cpu and vector is used to map interrupt for a direct
attached device. This because, once a device is marked for direct attach,
hypervisor will not let any interrupts be mapped to host. So it is mapped
to guest dummy cpu and dummy vector. This is then correctly mapped during
guest boot via the retarget paths.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
arch/arm64/include/asm/mshyperv.h | 15 +++++
arch/x86/hyperv/irqdomain.c | 57 +++++++++++++-----
arch/x86/include/asm/mshyperv.h | 4 ++
drivers/pci/controller/pci-hyperv.c | 91 +++++++++++++++++++++++++----
4 files changed, 142 insertions(+), 25 deletions(-)
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index b721d3134ab6..27da480f94f6 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -53,6 +53,21 @@ static inline u64 hv_get_non_nested_msr(unsigned int reg)
return hv_get_msr(reg);
}
+struct irq_data;
+struct msi_msg;
+struct pci_dev;
+static inline void hv_irq_compose_msi_msg(struct irq_data *data,
+ struct msi_msg *msg) {};
+static inline int hv_unmap_msi_interrupt(struct pci_dev *pdev,
+ struct hv_interrupt_entry *hvirqe)
+{
+ return -EOPNOTSUPP;
+}
+static inline bool hv_pcidev_is_attached_dev(struct pci_dev *pdev)
+{
+ return false;
+}
+
/* SMCCC hypercall parameters */
#define HV_SMCCC_FUNC_NUMBER 1
#define HV_FUNC_ID ARM_SMCCC_CALL_VAL( \
diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index 33017aa0caa4..e6eb457f791e 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -13,6 +13,16 @@
#include <linux/irqchip/irq-msi-lib.h>
#include <asm/mshyperv.h>
+/*
+ * For direct attached devices (which use logical device ids), hypervisor will
+ * not allow mappings to host. But VFIO needs to bind the interrupt at the very
+ * start before the guest cpu/vector is known. So we use dummy cpu and vector
+ * to bind in such case, and later when the guest starts, retarget will move it
+ * to correct guest cpu and vector.
+ */
+#define HV_DDA_DUMMY_CPU 0
+#define HV_DDA_DUMMY_VECTOR 32
+
static u64 hv_map_interrupt_hcall(u64 ptid, union hv_device_id hv_devid,
bool level, int cpu, int vector,
struct hv_interrupt_entry *ret_entry)
@@ -24,6 +34,11 @@ static u64 hv_map_interrupt_hcall(u64 ptid, union hv_device_id hv_devid,
u64 status;
int nr_bank, var_size;
+ if (hv_devid.device_type == HV_DEVICE_TYPE_LOGICAL) {
+ cpu = HV_DDA_DUMMY_CPU;
+ vector = HV_DDA_DUMMY_VECTOR;
+ }
+
local_irq_save(flags);
input = *this_cpu_ptr(hyperv_pcpu_input_arg);
@@ -95,7 +110,8 @@ static int hv_map_interrupt(u64 ptid, union hv_device_id device_id, bool level,
return hv_result_to_errno(status);
}
-static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry *irq_entry)
+static int hv_unmap_interrupt(union hv_device_id hv_devid,
+ struct hv_interrupt_entry *irq_entry)
{
unsigned long flags;
struct hv_input_unmap_device_interrupt *input;
@@ -103,10 +119,14 @@ static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry *irq_entry)
local_irq_save(flags);
input = *this_cpu_ptr(hyperv_pcpu_input_arg);
-
memset(input, 0, sizeof(*input));
- input->partition_id = hv_current_partition_id;
- input->device_id = id;
+
+ if (hv_devid.device_type == HV_DEVICE_TYPE_LOGICAL)
+ input->partition_id = hv_iommu_get_curr_partid();
+ else
+ input->partition_id = hv_current_partition_id;
+
+ input->device_id = hv_devid.as_uint64;
input->interrupt_entry = *irq_entry;
status = hv_do_hypercall(HVCALL_UNMAP_DEVICE_INTERRUPT, input, NULL);
@@ -263,6 +283,7 @@ static u64 hv_build_irq_devid(struct pci_dev *pdev)
int hv_map_msi_interrupt(struct irq_data *data,
struct hv_interrupt_entry *out_entry)
{
+ u64 ptid;
struct irq_cfg *cfg = irqd_cfg(data);
struct hv_interrupt_entry dummy;
union hv_device_id hv_devid;
@@ -275,8 +296,17 @@ int hv_map_msi_interrupt(struct irq_data *data,
hv_devid.as_uint64 = hv_build_irq_devid(pdev);
cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
- return hv_map_interrupt(hv_current_partition_id, hv_devid, false, cpu,
- cfg->vector, out_entry ? out_entry : &dummy);
+ if (hv_devid.device_type == HV_DEVICE_TYPE_LOGICAL)
+ if (hv_pcidev_is_attached_dev(pdev))
+ ptid = hv_iommu_get_curr_partid();
+ else
+ /* Device actually on l1vh root, not passthru'd to vm */
+ ptid = hv_current_partition_id;
+ else
+ ptid = hv_current_partition_id;
+
+ return hv_map_interrupt(ptid, hv_devid, false, cpu, cfg->vector,
+ out_entry ? out_entry : &dummy);
}
EXPORT_SYMBOL_GPL(hv_map_msi_interrupt);
@@ -289,10 +319,7 @@ static void entry_to_msi_msg(struct hv_interrupt_entry *entry,
msg->data = entry->msi_entry.data.as_uint32;
}
-static int hv_unmap_msi_interrupt(struct pci_dev *pdev,
- struct hv_interrupt_entry *irq_entry);
-
-static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
+void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
struct hv_interrupt_entry *stored_entry;
struct irq_cfg *cfg = irqd_cfg(data);
@@ -341,16 +368,18 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
data->chip_data = stored_entry;
entry_to_msi_msg(data->chip_data, msg);
}
+EXPORT_SYMBOL_GPL(hv_irq_compose_msi_msg);
-static int hv_unmap_msi_interrupt(struct pci_dev *pdev,
- struct hv_interrupt_entry *irq_entry)
+int hv_unmap_msi_interrupt(struct pci_dev *pdev,
+ struct hv_interrupt_entry *irq_entry)
{
union hv_device_id hv_devid;
hv_devid.as_uint64 = hv_build_irq_devid(pdev);
- return hv_unmap_interrupt(hv_devid.as_uint64, irq_entry);
+ return hv_unmap_interrupt(hv_devid, irq_entry);
}
+EXPORT_SYMBOL_GPL(hv_unmap_msi_interrupt);
/* NB: during map, hv_interrupt_entry is saved via data->chip_data */
static void hv_teardown_msi_irq(struct pci_dev *pdev, struct irq_data *irqd)
@@ -486,7 +515,7 @@ int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry)
hv_devid.device_type = HV_DEVICE_TYPE_IOAPIC;
hv_devid.ioapic.ioapic_id = (u8)ioapic_id;
- return hv_unmap_interrupt(hv_devid.as_uint64, entry);
+ return hv_unmap_interrupt(hv_devid, entry);
}
EXPORT_SYMBOL_GPL(hv_unmap_ioapic_interrupt);
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index e4ccdbbf1d12..b6facd3a0f5e 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -204,11 +204,15 @@ static inline u64 hv_iommu_get_curr_partid(void)
#endif /* CONFIG_HYPERV_IOMMU */
u64 hv_pci_vmbus_device_id(struct pci_dev *pdev);
+void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg);
+extern bool hv_no_attdev;
struct irq_domain *hv_create_pci_msi_domain(void);
int hv_map_msi_interrupt(struct irq_data *data,
struct hv_interrupt_entry *out_entry);
+int hv_unmap_msi_interrupt(struct pci_dev *dev,
+ struct hv_interrupt_entry *hvirqe);
int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
struct hv_interrupt_entry *entry);
int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 40f0b06bb966..71d1599dc4a8 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -660,15 +660,17 @@ static void hv_irq_retarget_interrupt(struct irq_data *data)
params = *this_cpu_ptr(hyperv_pcpu_input_arg);
memset(params, 0, sizeof(*params));
- params->partition_id = HV_PARTITION_ID_SELF;
+
+ if (hv_pcidev_is_attached_dev(pdev))
+ params->partition_id = hv_iommu_get_curr_partid();
+ else
+ params->partition_id = HV_PARTITION_ID_SELF;
+
params->int_entry.source = HV_INTERRUPT_SOURCE_MSI;
- params->int_entry.msi_entry.address.as_uint32 = int_desc->address & 0xffffffff;
+ params->int_entry.msi_entry.address.as_uint32 =
+ int_desc->address & 0xffffffff;
params->int_entry.msi_entry.data.as_uint32 = int_desc->data;
- params->device_id = (hbus->hdev->dev_instance.b[5] << 24) |
- (hbus->hdev->dev_instance.b[4] << 16) |
- (hbus->hdev->dev_instance.b[7] << 8) |
- (hbus->hdev->dev_instance.b[6] & 0xf8) |
- PCI_FUNC(pdev->devfn);
+ params->device_id = hv_pci_vmbus_device_id(pdev);
params->int_target.vector = hv_msi_get_int_vector(data);
if (hbus->protocol_version >= PCI_PROTOCOL_VERSION_1_2) {
@@ -1263,6 +1265,15 @@ static void _hv_pcifront_read_config(struct hv_pci_dev *hpdev, int where,
mb();
}
spin_unlock_irqrestore(&hbus->config_lock, flags);
+ /*
+ * Make sure PCI_INTERRUPT_PIN is hard-wired to 0 since it may
+ * be read using a 32bit read which is skipped by the above
+ * emulation.
+ */
+ if (PCI_INTERRUPT_PIN >= where &&
+ PCI_INTERRUPT_PIN <= (where + size)) {
+ *((char *)val + PCI_INTERRUPT_PIN - where) = 0;
+ }
} else {
dev_err(dev, "Attempt to read beyond a function's config space.\n");
}
@@ -1731,14 +1742,22 @@ static void hv_msi_free(struct irq_domain *domain, unsigned int irq)
if (!int_desc)
return;
- irq_data->chip_data = NULL;
hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(pdev->devfn));
if (!hpdev) {
+ irq_data->chip_data = NULL;
kfree(int_desc);
return;
}
- hv_int_desc_free(hpdev, int_desc);
+ if (hv_pcidev_is_attached_dev(pdev)) {
+ hv_unmap_msi_interrupt(pdev, irq_data->chip_data);
+ kfree(irq_data->chip_data);
+ irq_data->chip_data = NULL;
+ } else {
+ irq_data->chip_data = NULL;
+ hv_int_desc_free(hpdev, int_desc);
+ }
+
put_pcichild(hpdev);
}
@@ -2139,6 +2158,56 @@ static void hv_vmbus_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
msg->data = 0;
}
+/* Compose an msi message for a directly attached device */
+static void hv_dda_compose_msi_msg(struct irq_data *irq_data,
+ struct msi_desc *msi_desc,
+ struct msi_msg *msg)
+{
+ bool multi_msi;
+ struct hv_pcibus_device *hbus;
+ struct hv_pci_dev *hpdev;
+ struct pci_dev *pdev = msi_desc_to_pci_dev(msi_desc);
+
+ multi_msi = !msi_desc->pci.msi_attrib.is_msix &&
+ msi_desc->nvec_used > 1;
+
+ if (multi_msi) {
+ dev_err(&hbus->hdev->device,
+ "Passthru direct attach does not support multi msi\n");
+ goto outerr;
+ }
+
+ hbus = container_of(pdev->bus->sysdata, struct hv_pcibus_device,
+ sysdata);
+
+ hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(pdev->devfn));
+ if (!hpdev)
+ goto outerr;
+
+ /* will unmap if needed and also update irq_data->chip_data */
+ hv_irq_compose_msi_msg(irq_data, msg);
+
+ put_pcichild(hpdev);
+ return;
+
+outerr:
+ memset(msg, 0, sizeof(*msg));
+}
+
+static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
+{
+ struct pci_dev *pdev;
+ struct msi_desc *msi_desc;
+
+ msi_desc = irq_data_get_msi_desc(data);
+ pdev = msi_desc_to_pci_dev(msi_desc);
+
+ if (hv_pcidev_is_attached_dev(pdev))
+ hv_dda_compose_msi_msg(data, msi_desc, msg);
+ else
+ hv_vmbus_compose_msi_msg(data, msg);
+}
+
static bool hv_pcie_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
struct irq_domain *real_parent, struct msi_domain_info *info)
{
@@ -2177,7 +2246,7 @@ static const struct msi_parent_ops hv_pcie_msi_parent_ops = {
/* HW Interrupt Chip Descriptor */
static struct irq_chip hv_msi_irq_chip = {
.name = "Hyper-V PCIe MSI",
- .irq_compose_msi_msg = hv_vmbus_compose_msi_msg,
+ .irq_compose_msi_msg = hv_compose_msi_msg,
.irq_set_affinity = irq_chip_set_affinity_parent,
.irq_ack = irq_chip_ack_parent,
.irq_eoi = irq_chip_eoi_parent,
@@ -4096,7 +4165,7 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
irq_data = irq_get_irq_data(entry->irq);
if (WARN_ON_ONCE(!irq_data))
return -EINVAL;
- hv_vmbus_compose_msi_msg(irq_data, &entry->msg);
+ hv_compose_msi_msg(irq_data, &entry->msg);
}
return 0;
}
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:28 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Upon guest access, in case of missing mmio mapping, the hypervisor
generates an unmapped gpa intercept. In this path, lookup the PCI
resource pfn for the guest gpa, and ask the hypervisor to map it
via hypercall. The PCI resource pfn is maintained by the VFIO driver,
and obtained via fixup_user_fault call (similar to KVM).
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
drivers/hv/mshv_root_main.c | 115 ++++++++++++++++++++++++++++++++++++
1 file changed, 115 insertions(+)
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 03f3aa9f5541..4c8bc7cd0888 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -56,6 +56,14 @@ struct hv_stats_page {
};
} __packed;
+bool hv_nofull_mmio; /* don't map entire mmio region upon fault */
+static int __init setup_hv_full_mmio(char *str)
+{
+ hv_nofull_mmio = true;
+ return 0;
+}
+__setup("hv_nofull_mmio", setup_hv_full_mmio);
+
struct mshv_root mshv_root;
enum hv_scheduler_type hv_scheduler_type;
@@ -612,6 +620,109 @@ mshv_partition_region_by_gfn(struct mshv_partition *partition, u64 gfn)
}
#ifdef CONFIG_X86_64
+
+/*
+ * Check if uaddr is for mmio range. If yes, return 0 with mmio_pfn filled in
+ * else just return -errno.
+ */
+static int mshv_chk_get_mmio_start_pfn(struct mshv_partition *pt, u64 gfn,
+ u64 *mmio_pfnp)
+{
+ struct vm_area_struct *vma;
+ bool is_mmio;
+ u64 uaddr;
+ struct mshv_mem_region *mreg;
+ struct follow_pfnmap_args pfnmap_args;
+ int rc = -EINVAL;
+
+ /*
+ * Do not allow mem region to be deleted beneath us. VFIO uses
+ * useraddr vma to lookup pci bar pfn.
+ */
+ spin_lock(&pt->pt_mem_regions_lock);
+
+ /* Get the region again under the lock */
+ mreg = mshv_partition_region_by_gfn(pt, gfn);
+ if (mreg == NULL || mreg->type != MSHV_REGION_TYPE_MMIO)
+ goto unlock_pt_out;
+
+ uaddr = mreg->start_uaddr +
+ ((gfn - mreg->start_gfn) << HV_HYP_PAGE_SHIFT);
+
+ mmap_read_lock(current->mm);
+ vma = vma_lookup(current->mm, uaddr);
+ is_mmio = vma ? !!(vma->vm_flags & (VM_IO | VM_PFNMAP)) : 0;
+ if (!is_mmio)
+ goto unlock_mmap_out;
+
+ pfnmap_args.vma = vma;
+ pfnmap_args.address = uaddr;
+
+ rc = follow_pfnmap_start(&pfnmap_args);
+ if (rc) {
+ rc = fixup_user_fault(current->mm, uaddr, FAULT_FLAG_WRITE,
+ NULL);
+ if (rc)
+ goto unlock_mmap_out;
+
+ rc = follow_pfnmap_start(&pfnmap_args);
+ if (rc)
+ goto unlock_mmap_out;
+ }
+
+ *mmio_pfnp = pfnmap_args.pfn;
+ follow_pfnmap_end(&pfnmap_args);
+
+unlock_mmap_out:
+ mmap_read_unlock(current->mm);
+unlock_pt_out:
+ spin_unlock(&pt->pt_mem_regions_lock);
+ return rc;
+}
+
+/*
+ * At present, the only unmapped gpa is mmio space. Verify if it's mmio
+ * and resolve if possible.
+ * Returns: True if valid mmio intercept and it was handled, else false
+ */
+static bool mshv_handle_unmapped_gpa(struct mshv_vp *vp)
+{
+ struct hv_message *hvmsg = vp->vp_intercept_msg_page;
+ struct hv_x64_memory_intercept_message *msg;
+ union hv_x64_memory_access_info accinfo;
+ u64 gfn, mmio_spa, numpgs;
+ struct mshv_mem_region *mreg;
+ int rc;
+ struct mshv_partition *pt = vp->vp_partition;
+
+ msg = (struct hv_x64_memory_intercept_message *)hvmsg->u.payload;
+ accinfo = msg->memory_access_info;
+
+ if (!accinfo.gva_gpa_valid)
+ return false;
+
+ /* Do a fast check and bail if non mmio intercept */
+ gfn = msg->guest_physical_address >> HV_HYP_PAGE_SHIFT;
+ mreg = mshv_partition_region_by_gfn(pt, gfn);
+ if (mreg == NULL || mreg->type != MSHV_REGION_TYPE_MMIO)
+ return false;
+
+ rc = mshv_chk_get_mmio_start_pfn(pt, gfn, &mmio_spa);
+ if (rc)
+ return false;
+
+ if (!hv_nofull_mmio) { /* default case */
+ gfn = mreg->start_gfn;
+ mmio_spa = mmio_spa - (gfn - mreg->start_gfn);
+ numpgs = mreg->nr_pages;
+ } else
+ numpgs = 1;
+
+ rc = hv_call_map_mmio_pages(pt->pt_id, gfn, mmio_spa, numpgs);
+
+ return rc == 0;
+}
+
static struct mshv_mem_region *
mshv_partition_region_by_gfn_get(struct mshv_partition *p, u64 gfn)
{
@@ -666,13 +777,17 @@ static bool mshv_handle_gpa_intercept(struct mshv_vp *vp)
return ret;
}
+
#else /* CONFIG_X86_64 */
+static bool mshv_handle_unmapped_gpa(struct mshv_vp *vp) { return false; }
static bool mshv_handle_gpa_intercept(struct mshv_vp *vp) { return false; }
#endif /* CONFIG_X86_64 */
static bool mshv_vp_handle_intercept(struct mshv_vp *vp)
{
switch (vp->vp_intercept_msg_page->header.message_type) {
+ case HVMSG_UNMAPPED_GPA:
+ return mshv_handle_unmapped_gpa(vp);
case HVMSG_GPA_INTERCEPT:
return mshv_handle_gpa_intercept(vp);
}
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:30 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
VFIO no longer puts the mmio pfn in vma->vm_pgoff. So, remove code
that is using it to map mmio space. It is broken and will cause
panic.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
drivers/hv/mshv_root_main.c | 20 ++++----------------
1 file changed, 4 insertions(+), 16 deletions(-)
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 27313419828d..03f3aa9f5541 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1258,16 +1258,8 @@ static int mshv_prepare_pinned_region(struct mshv_mem_region *region)
}
/*
- * This maps two things: guest RAM and for pci passthru mmio space.
- *
- * mmio:
- * - vfio overloads vm_pgoff to store the mmio start pfn/spa.
- * - Two things need to happen for mapping mmio range:
- * 1. mapped in the uaddr so VMM can access it.
- * 2. mapped in the hwpt (gfn <-> mmio phys addr) so guest can access it.
- *
- * This function takes care of the second. The first one is managed by vfio,
- * and hence is taken care of via vfio_pci_mmap_fault().
+ * This is called for both user ram and mmio space. The mmio space is not
+ * mapped here, but later during intercept.
*/
static long
mshv_map_user_memory(struct mshv_partition *partition,
@@ -1276,7 +1268,6 @@ mshv_map_user_memory(struct mshv_partition *partition,
struct mshv_mem_region *region;
struct vm_area_struct *vma;
bool is_mmio;
- ulong mmio_pfn;
long ret;
if (mem.flags & BIT(MSHV_SET_MEM_BIT_UNMAP) ||
@@ -1286,7 +1277,6 @@ mshv_map_user_memory(struct mshv_partition *partition,
mmap_read_lock(current->mm);
vma = vma_lookup(current->mm, mem.userspace_addr);
is_mmio = vma ? !!(vma->vm_flags & (VM_IO | VM_PFNMAP)) : 0;
- mmio_pfn = is_mmio ? vma->vm_pgoff : 0;
mmap_read_unlock(current->mm);
if (!vma)
@@ -1313,10 +1303,8 @@ mshv_map_user_memory(struct mshv_partition *partition,
HV_MAP_GPA_NO_ACCESS, NULL);
break;
case MSHV_REGION_TYPE_MMIO:
- ret = hv_call_map_mmio_pages(partition->pt_id,
- region->start_gfn,
- mmio_pfn,
- region->nr_pages);
+ /* mmio mappings are handled later during intercepts */
+ ret = 0;
break;
}
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:29 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Import/copy from Hyper-V public headers, definitions and declarations that
are related to attaching and detaching of device domains and interrupt
remapping, and building device ids for those purposes.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
include/hyperv/hvgdk_mini.h | 11 ++++
include/hyperv/hvhdk_mini.h | 112 ++++++++++++++++++++++++++++++++++++
2 files changed, 123 insertions(+)
diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
index 04b18d0e37af..bda9fae5b1ef 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -323,6 +323,9 @@ union hv_hypervisor_version_info {
/* stimer Direct Mode is available */
#define HV_STIMER_DIRECT_MODE_AVAILABLE BIT(19)
+#define HV_DEVICE_DOMAIN_AVAILABLE BIT(24)
+#define HV_S1_DEVICE_DOMAIN_AVAILABLE BIT(25)
+
/*
* Implementation recommendations. Indicates which behaviors the hypervisor
* recommends the OS implement for optimal performance.
@@ -471,6 +474,8 @@ union hv_vp_assist_msr_contents { /* HV_REGISTER_VP_ASSIST_PAGE */
#define HVCALL_MAP_DEVICE_INTERRUPT 0x007c
#define HVCALL_UNMAP_DEVICE_INTERRUPT 0x007d
#define HVCALL_RETARGET_INTERRUPT 0x007e
+#define HVCALL_ATTACH_DEVICE 0x0082
+#define HVCALL_DETACH_DEVICE 0x0083
#define HVCALL_NOTIFY_PARTITION_EVENT 0x0087
#define HVCALL_ENTER_SLEEP_STATE 0x0084
#define HVCALL_NOTIFY_PORT_RING_EMPTY 0x008b
@@ -482,9 +487,15 @@ union hv_vp_assist_msr_contents { /* HV_REGISTER_VP_ASSIST_PAGE */
#define HVCALL_GET_VP_INDEX_FROM_APIC_ID 0x009a
#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0
+#define HVCALL_CREATE_DEVICE_DOMAIN 0x00b1
+#define HVCALL_ATTACH_DEVICE_DOMAIN 0x00b2
+#define HVCALL_MAP_DEVICE_GPA_PAGES 0x00b3
+#define HVCALL_UNMAP_DEVICE_GPA_PAGES 0x00b4
#define HVCALL_SIGNAL_EVENT_DIRECT 0x00c0
#define HVCALL_POST_MESSAGE_DIRECT 0x00c1
#define HVCALL_DISPATCH_VP 0x00c2
+#define HVCALL_DETACH_DEVICE_DOMAIN 0x00c4
+#define HVCALL_DELETE_DEVICE_DOMAIN 0x00c5
#define HVCALL_GET_GPA_PAGES_ACCESS_STATES 0x00c9
#define HVCALL_ACQUIRE_SPARSE_SPA_PAGE_HOST_ACCESS 0x00d7
#define HVCALL_RELEASE_SPARSE_SPA_PAGE_HOST_ACCESS 0x00d8
diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h
index 41a29bf8ec14..57821d6ddb61 100644
--- a/include/hyperv/hvhdk_mini.h
+++ b/include/hyperv/hvhdk_mini.h
@@ -449,6 +449,32 @@ struct hv_send_ipi_ex { /* HV_INPUT_SEND_SYNTHETIC_CLUSTER_IPI_EX */
struct hv_vpset vp_set;
} __packed;
+union hv_attdev_flags { /* HV_ATTACH_DEVICE_FLAGS */
+ struct {
+ u32 logical_id : 1;
+ u32 resvd0 : 1;
+ u32 ats_enabled : 1;
+ u32 virt_func : 1;
+ u32 shared_irq_child : 1;
+ u32 virt_dev : 1;
+ u32 ats_supported : 1;
+ u32 small_irt : 1;
+ u32 resvd : 24;
+ } __packed;
+ u32 as_uint32;
+};
+
+union hv_dev_pci_caps { /* HV_DEVICE_PCI_CAPABILITIES */
+ struct {
+ u32 max_pasid_width : 5;
+ u32 invalidate_qdepth : 5;
+ u32 global_inval : 1;
+ u32 prg_response_req : 1;
+ u32 resvd : 20;
+ } __packed;
+ u32 as_uint32;
+};
+
typedef u16 hv_pci_rid; /* HV_PCI_RID */
typedef u16 hv_pci_segment; /* HV_PCI_SEGMENT */
typedef u64 hv_logical_device_id;
@@ -528,4 +554,90 @@ union hv_device_id { /* HV_DEVICE_ID */
} acpi;
} __packed;
+struct hv_input_attach_device { /* HV_INPUT_ATTACH_DEVICE */
+ u64 partition_id;
+ union hv_device_id device_id;
+ union hv_attdev_flags attdev_flags;
+ u8 attdev_vtl;
+ u8 rsvd0;
+ u16 rsvd1;
+ u64 logical_devid;
+ union hv_dev_pci_caps dev_pcicaps;
+ u16 pf_pci_rid;
+ u16 resvd2;
+} __packed;
+
+struct hv_input_detach_device { /* HV_INPUT_DETACH_DEVICE */
+ u64 partition_id;
+ u64 logical_devid;
+} __packed;
+
+
+/* 3 domain types: stage 1, stage 2, and SOC */
+#define HV_DEVICE_DOMAIN_TYPE_S2 0 /* HV_DEVICE_DOMAIN_ID_TYPE_S2 */
+#define HV_DEVICE_DOMAIN_TYPE_S1 1 /* HV_DEVICE_DOMAIN_ID_TYPE_S1 */
+#define HV_DEVICE_DOMAIN_TYPE_SOC 2 /* HV_DEVICE_DOMAIN_ID_TYPE_SOC */
+
+/* ID for stage 2 default domain and NULL domain */
+#define HV_DEVICE_DOMAIN_ID_S2_DEFAULT 0
+#define HV_DEVICE_DOMAIN_ID_S2_NULL 0xFFFFFFFFULL
+
+union hv_device_domain_id {
+ u64 as_uint64;
+ struct {
+ u32 type : 4;
+ u32 reserved : 28;
+ u32 id;
+ };
+} __packed;
+
+struct hv_input_device_domain { /* HV_INPUT_DEVICE_DOMAIN */
+ u64 partition_id;
+ union hv_input_vtl owner_vtl;
+ u8 padding[7];
+ union hv_device_domain_id domain_id;
+} __packed;
+
+union hv_create_device_domain_flags { /* HV_CREATE_DEVICE_DOMAIN_FLAGS */
+ u32 as_uint32;
+ struct {
+ u32 forward_progress_required : 1;
+ u32 inherit_owning_vtl : 1;
+ u32 reserved : 30;
+ } __packed;
+} __packed;
+
+struct hv_input_create_device_domain { /* HV_INPUT_CREATE_DEVICE_DOMAIN */
+ struct hv_input_device_domain device_domain;
+ union hv_create_device_domain_flags create_device_domain_flags;
+} __packed;
+
+struct hv_input_delete_device_domain { /* HV_INPUT_DELETE_DEVICE_DOMAIN */
+ struct hv_input_device_domain device_domain;
+} __packed;
+
+struct hv_input_attach_device_domain { /* HV_INPUT_ATTACH_DEVICE_DOMAIN */
+ struct hv_input_device_domain device_domain;
+ union hv_device_id device_id;
+} __packed;
+
+struct hv_input_detach_device_domain { /* HV_INPUT_DETACH_DEVICE_DOMAIN */
+ u64 partition_id;
+ union hv_device_id device_id;
+} __packed;
+
+struct hv_input_map_device_gpa_pages { /* HV_INPUT_MAP_DEVICE_GPA_PAGES */
+ struct hv_input_device_domain device_domain;
+ union hv_input_vtl target_vtl;
+ u8 padding[3];
+ u32 map_flags;
+ u64 target_device_va_base;
+ u64 gpa_page_list[];
+} __packed;
+
+struct hv_input_unmap_device_gpa_pages { /* HV_INPUT_UNMAP_DEVICE_GPA_PAGES */
+ struct hv_input_device_domain device_domain;
+ u64 target_device_va_base;
+} __packed;
+
#endif /* _HV_HVHDK_MINI_H */
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:24 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
On Hyper-V, most hypercalls related to PCI passthru to map/unmap regions,
interrupts, etc need a device id as a parameter. This device id refers
to that specific device during the lifetime of passthru.
An L1VH VM only contains VMBus based devices. A device id for a VMBus
device is slightly different in that it uses the hv_pcibus_device info
for building it to make sure it matches exactly what the hypervisor
expects. This VMBus based device id is needed when attaching devices in
an L1VH based guest VM. Before building it, a check is done to make sure
the device is a valid VMBus device.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
arch/x86/include/asm/mshyperv.h | 2 ++
drivers/pci/controller/pci-hyperv.c | 29 +++++++++++++++++++++++++++++
2 files changed, 31 insertions(+)
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index eef4c3a5ba28..0d7fdfb25e76 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -188,6 +188,8 @@ bool hv_vcpu_is_preempted(int vcpu);
static inline void hv_apic_init(void) {}
#endif
+u64 hv_pci_vmbus_device_id(struct pci_dev *pdev);
+
struct irq_domain *hv_create_pci_msi_domain(void);
int hv_map_msi_interrupt(struct irq_data *data,
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 8bc6a38c9b5a..40f0b06bb966 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -579,6 +579,8 @@ static void hv_pci_onchannelcallback(void *context);
#define DELIVERY_MODE APIC_DELIVERY_MODE_FIXED
#define HV_MSI_CHIP_FLAGS MSI_CHIP_FLAG_SET_ACK
+static bool hv_vmbus_pci_device(struct pci_bus *pbus);
+
static int hv_pci_irqchip_init(void)
{
return 0;
@@ -598,6 +600,26 @@ static unsigned int hv_msi_get_int_vector(struct irq_data *data)
#define hv_msi_prepare pci_msi_prepare
+u64 hv_pci_vmbus_device_id(struct pci_dev *pdev)
+{
+ u64 u64val;
+ struct hv_pcibus_device *hbus;
+ struct pci_bus *pbus = pdev->bus;
+
+ if (!hv_vmbus_pci_device(pbus))
+ return 0;
+
+ hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);
+ u64val = (hbus->hdev->dev_instance.b[5] << 24) |
+ (hbus->hdev->dev_instance.b[4] << 16) |
+ (hbus->hdev->dev_instance.b[7] << 8) |
+ (hbus->hdev->dev_instance.b[6] & 0xf8) |
+ PCI_FUNC(pdev->devfn);
+
+ return u64val;
+}
+EXPORT_SYMBOL_GPL(hv_pci_vmbus_device_id);
+
/**
* hv_irq_retarget_interrupt() - "Unmask" the IRQ by setting its current
* affinity.
@@ -1404,6 +1426,13 @@ static struct pci_ops hv_pcifront_ops = {
.write = hv_pcifront_write_config,
};
+#ifdef CONFIG_X86
+static bool hv_vmbus_pci_device(struct pci_bus *pbus)
+{
+ return pbus->ops == &hv_pcifront_ops;
+}
+#endif /* CONFIG_X86 */
+
/*
* Paravirtual backchannel
*
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:25 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
On Hyper-V, most hypercalls related to PCI passthru to map/unmap regions,
interrupts, etc need a device id as a parameter. A device id refers
to a specific device. A device id is of two types:
o Logical: used for direct attach (see below) hypercalls. A logical
device id is a unique 62bit value that is created and
sent during the initial device attach. Then all further
communications (for interrupt remaps etc) must use this
logical id.
o PCI: used for device domain hypercalls such as map, unmap, etc.
This is built using actual device BDF info.
PS: Since an L1VH only supports direct attaches, a logical device id
on an L1VH VM is always a VMBus device id. For non-L1VH cases,
we just use PCI BDF info, altho not strictly needed, to build the
logical device id.
At a high level, Hyper-V supports two ways to do PCI passthru:
1. Device Domain: root must create a device domain in the hypervisor,
and do map/unmap hypercalls for mapping and unmapping guest RAM.
All hypervisor communications use device id of type PCI for
identifying and referencing the device.
2. Direct Attach: the hypervisor will simply use the guest's HW
page table for mappings, thus the host need not do map/unmap
hypercalls. A direct attached device must be referenced
via logical device id and never via the PCI device id. For an
L1VH root/parent, Hyper-V only supports direct attaches.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
arch/x86/hyperv/irqdomain.c | 60 ++++++++++++++++++++++++++++++---
arch/x86/include/asm/mshyperv.h | 14 ++++++++
2 files changed, 70 insertions(+), 4 deletions(-)
diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index ccbe5848a28f..33017aa0caa4 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -137,7 +137,7 @@ static int get_rid_cb(struct pci_dev *pdev, u16 alias, void *data)
return 0;
}
-static union hv_device_id hv_build_devid_type_pci(struct pci_dev *pdev)
+static u64 hv_build_devid_type_pci(struct pci_dev *pdev)
{
int pos;
union hv_device_id hv_devid;
@@ -197,7 +197,58 @@ static union hv_device_id hv_build_devid_type_pci(struct pci_dev *pdev)
}
out:
- return hv_devid;
+ return hv_devid.as_uint64;
+}
+
+/* Build device id for direct attached devices */
+static u64 hv_build_devid_type_logical(struct pci_dev *pdev)
+{
+ hv_pci_segment segment;
+ union hv_device_id hv_devid;
+ union hv_pci_bdf bdf = {.as_uint16 = 0};
+ struct rid_data data = {
+ .bridge = NULL,
+ .rid = PCI_DEVID(pdev->bus->number, pdev->devfn)
+ };
+
+ segment = pci_domain_nr(pdev->bus);
+ bdf.bus = PCI_BUS_NUM(data.rid);
+ bdf.device = PCI_SLOT(data.rid);
+ bdf.function = PCI_FUNC(data.rid);
+
+ hv_devid.as_uint64 = 0;
+ hv_devid.device_type = HV_DEVICE_TYPE_LOGICAL;
+ hv_devid.logical.id = (u64)segment << 16 | bdf.as_uint16;
+
+ return hv_devid.as_uint64;
+}
+
+/* Build device id after the device has been attached */
+u64 hv_build_devid_oftype(struct pci_dev *pdev, enum hv_device_type type)
+{
+ if (type == HV_DEVICE_TYPE_LOGICAL) {
+ if (hv_l1vh_partition())
+ return hv_pci_vmbus_device_id(pdev);
+ else
+ return hv_build_devid_type_logical(pdev);
+ } else if (type == HV_DEVICE_TYPE_PCI)
+ return hv_build_devid_type_pci(pdev);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(hv_build_devid_oftype);
+
+/* Build device id for the interrupt path */
+static u64 hv_build_irq_devid(struct pci_dev *pdev)
+{
+ enum hv_device_type dev_type;
+
+ if (hv_pcidev_is_attached_dev(pdev) || hv_l1vh_partition())
+ dev_type = HV_DEVICE_TYPE_LOGICAL;
+ else
+ dev_type = HV_DEVICE_TYPE_PCI;
+
+ return hv_build_devid_oftype(pdev, dev_type);
}
/*
@@ -221,7 +272,7 @@ int hv_map_msi_interrupt(struct irq_data *data,
msidesc = irq_data_get_msi_desc(data);
pdev = msi_desc_to_pci_dev(msidesc);
- hv_devid = hv_build_devid_type_pci(pdev);
+ hv_devid.as_uint64 = hv_build_irq_devid(pdev);
cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
return hv_map_interrupt(hv_current_partition_id, hv_devid, false, cpu,
@@ -296,7 +347,8 @@ static int hv_unmap_msi_interrupt(struct pci_dev *pdev,
{
union hv_device_id hv_devid;
- hv_devid = hv_build_devid_type_pci(pdev);
+ hv_devid.as_uint64 = hv_build_irq_devid(pdev);
+
return hv_unmap_interrupt(hv_devid.as_uint64, irq_entry);
}
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 0d7fdfb25e76..97477c5a8487 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -188,6 +188,20 @@ bool hv_vcpu_is_preempted(int vcpu);
static inline void hv_apic_init(void) {}
#endif
+#if IS_ENABLED(CONFIG_HYPERV_IOMMU)
+static inline bool hv_pcidev_is_attached_dev(struct pci_dev *pdev)
+{ return false; } /* temporary */
+u64 hv_build_devid_oftype(struct pci_dev *pdev, enum hv_device_type type);
+#else /* CONFIG_HYPERV_IOMMU */
+static inline bool hv_pcidev_is_attached_dev(struct pci_dev *pdev)
+{ return false; }
+
+static inline u64 hv_build_devid_oftype(struct pci_dev *pdev,
+ enum hv_device_type type)
+{ return 0; }
+
+#endif /* CONFIG_HYPERV_IOMMU */
+
u64 hv_pci_vmbus_device_id(struct pci_dev *pdev);
struct irq_domain *hv_create_pci_msi_domain(void);
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:26 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Add a new file to implement management of device domains, mapping and
unmapping of iommu memory, and other iommu_ops to fit within the VFIO
framework for PCI passthru on Hyper-V running Linux as root or L1VH
parent. This also implements direct attach mechanism for PCI passthru,
and it is also made to work within the VFIO framework.
At a high level, during boot the hypervisor creates a default identity
domain and attaches all devices to it. This nicely maps to Linux iommu
subsystem IOMMU_DOMAIN_IDENTITY domain. As a result, Linux does not
need to explicitly ask Hyper-V to attach devices and do maps/unmaps
during boot. As mentioned previously, Hyper-V supports two ways to do
PCI passthru:
1. Device Domain: root must create a device domain in the hypervisor,
and do map/unmap hypercalls for mapping and unmapping guest RAM.
All hypervisor communications use device id of type PCI for
identifying and referencing the device.
2. Direct Attach: the hypervisor will simply use the guest's HW
page table for mappings, thus the host need not do map/unmap
device memory hypercalls. As such, direct attach passthru setup
during guest boot is extremely fast. A direct attached device
must be referenced via logical device id and not via the PCI
device id.
At present, L1VH root/parent only supports direct attaches. Also direct
attach is default in non-L1VH cases because there are some significant
performance issues with device domain implementation currently for guests
with higher RAM (say more than 8GB), and that unfortunately cannot be
addressed in the short term.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
MAINTAINERS | 1 +
arch/x86/include/asm/mshyperv.h | 7 +-
arch/x86/kernel/pci-dma.c | 2 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 876 ++++++++++++++++++++++++++++++++
include/linux/hyperv.h | 6 +
6 files changed, 890 insertions(+), 4 deletions(-)
create mode 100644 drivers/iommu/hyperv-iommu.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 381a0e086382..63160cee942c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11741,6 +11741,7 @@ F: drivers/hid/hid-hyperv.c
F: drivers/hv/
F: drivers/infiniband/hw/mana/
F: drivers/input/serio/hyperv-keyboard.c
+F: drivers/iommu/hyperv-iommu.c
F: drivers/iommu/hyperv-irq.c
F: drivers/net/ethernet/microsoft/
F: drivers/net/hyperv/
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 97477c5a8487..e4ccdbbf1d12 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -189,16 +189,17 @@ static inline void hv_apic_init(void) {}
#endif
#if IS_ENABLED(CONFIG_HYPERV_IOMMU)
-static inline bool hv_pcidev_is_attached_dev(struct pci_dev *pdev)
-{ return false; } /* temporary */
+bool hv_pcidev_is_attached_dev(struct pci_dev *pdev);
u64 hv_build_devid_oftype(struct pci_dev *pdev, enum hv_device_type type);
+u64 hv_iommu_get_curr_partid(void);
#else /* CONFIG_HYPERV_IOMMU */
static inline bool hv_pcidev_is_attached_dev(struct pci_dev *pdev)
{ return false; }
-
static inline u64 hv_build_devid_oftype(struct pci_dev *pdev,
enum hv_device_type type)
{ return 0; }
+static inline u64 hv_iommu_get_curr_partid(void)
+{ return HV_PARTITION_ID_INVALID; }
#endif /* CONFIG_HYPERV_IOMMU */
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 6267363e0189..cfeee6505e17 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -8,6 +8,7 @@
#include <linux/gfp.h>
#include <linux/pci.h>
#include <linux/amd-iommu.h>
+#include <linux/hyperv.h>
#include <asm/proto.h>
#include <asm/dma.h>
@@ -105,6 +106,7 @@ void __init pci_iommu_alloc(void)
gart_iommu_hole_init();
amd_iommu_detect();
detect_intel_iommu();
+ hv_iommu_detect();
swiotlb_init(x86_swiotlb_enable, x86_swiotlb_flags);
}
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 598c39558e7d..cc9774864b00 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -30,7 +30,7 @@ obj-$(CONFIG_TEGRA_IOMMU_SMMU) += tegra-smmu.o
obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
-obj-$(CONFIG_HYPERV_IOMMU) += hyperv-irq.o
+obj-$(CONFIG_HYPERV_IOMMU) += hyperv-irq.o hyperv-iommu.o
obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o
obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o
diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c
new file mode 100644
index 000000000000..548483fec6b1
--- /dev/null
+++ b/drivers/iommu/hyperv-iommu.c
@@ -0,0 +1,876 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Hyper-V root vIOMMU driver.
+ * Copyright (C) 2026, Microsoft, Inc.
+ */
+
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/dmar.h>
+#include <linux/dma-map-ops.h>
+#include <linux/interval_tree.h>
+#include <linux/hyperv.h>
+#include "dma-iommu.h"
+#include <asm/iommu.h>
+#include <asm/mshyperv.h>
+
+/* We will not claim these PCI devices, eg hypervisor needs it for debugger */
+static char *pci_devs_to_skip;
+static int __init hv_iommu_setup_skip(char *str)
+{
+ pci_devs_to_skip = str;
+
+ return 0;
+}
+/* hv_iommu_skip=(SSSS:BB:DD.F)(SSSS:BB:DD.F) */
+__setup("hv_iommu_skip=", hv_iommu_setup_skip);
+
+bool hv_no_attdev; /* disable direct device attach for passthru */
+EXPORT_SYMBOL_GPL(hv_no_attdev);
+static int __init setup_hv_no_attdev(char *str)
+{
+ hv_no_attdev = true;
+ return 0;
+}
+__setup("hv_no_attdev", setup_hv_no_attdev);
+
+/* Iommu device that we export to the world. HyperV supports max of one */
+static struct iommu_device hv_virt_iommu;
+
+struct hv_domain {
+ struct iommu_domain iommu_dom;
+ u32 domid_num; /* as opposed to domain_id.type */
+ u32 num_attchd; /* number of currently attached devices */
+ bool attached_dom; /* is this direct attached dom? */
+ spinlock_t mappings_lock; /* protects mappings_tree */
+ struct rb_root_cached mappings_tree; /* iova to pa lookup tree */
+};
+
+#define to_hv_domain(d) container_of(d, struct hv_domain, iommu_dom)
+
+struct hv_iommu_mapping {
+ phys_addr_t paddr;
+ struct interval_tree_node iova;
+ u32 flags;
+};
+
+/*
+ * By default, during boot the hypervisor creates one Stage 2 (S2) default
+ * domain. Stage 2 means that the page table is controlled by the hypervisor.
+ * S2 default: access to entire root partition memory. This for us easily
+ * maps to IOMMU_DOMAIN_IDENTITY in the iommu subsystem, and
+ * is called HV_DEVICE_DOMAIN_ID_S2_DEFAULT in the hypervisor.
+ *
+ * Device Management:
+ * There are two ways to manage device attaches to domains:
+ * 1. Domain Attach: A device domain is created in the hypervisor, the
+ * device is attached to this domain, and then memory
+ * ranges are mapped in the map callbacks.
+ * 2. Direct Attach: No need to create a domain in the hypervisor for direct
+ * attached devices. A hypercall is made to tell the
+ * hypervisor to attach the device to a guest. There is
+ * no need for explicit memory mappings because the
+ * hypervisor will just use the guest HW page table.
+ *
+ * Since a direct attach is much faster, it is the default. This can be
+ * changed via hv_no_attdev.
+ *
+ * L1VH: hypervisor only supports direct attach.
+ */
+
+/*
+ * Create dummy domain to correspond to hypervisor prebuilt default identity
+ * domain (dummy because we do not make hypercall to create them).
+ */
+static struct hv_domain hv_def_identity_dom;
+
+static bool hv_special_domain(struct hv_domain *hvdom)
+{
+ return hvdom == &hv_def_identity_dom;
+}
+
+struct iommu_domain_geometry default_geometry = (struct iommu_domain_geometry) {
+ .aperture_start = 0,
+ .aperture_end = -1UL,
+ .force_aperture = true,
+};
+
+/*
+ * Since the relevant hypercalls can only fit less than 512 PFNs in the pfn
+ * array, report 1M max.
+ */
+#define HV_IOMMU_PGSIZES (SZ_4K | SZ_1M)
+
+static u32 unique_id; /* unique numeric id of a new domain */
+
+static void hv_iommu_detach_dev(struct iommu_domain *immdom,
+ struct device *dev);
+static size_t hv_iommu_unmap_pages(struct iommu_domain *immdom, ulong iova,
+ size_t pgsize, size_t pgcount,
+ struct iommu_iotlb_gather *gather);
+
+/*
+ * If the current thread is a VMM thread, return the partition id of the VM it
+ * is managing, else return HV_PARTITION_ID_INVALID.
+ */
+u64 hv_iommu_get_curr_partid(void)
+{
+ u64 (*fn)(pid_t pid);
+ u64 partid;
+
+ fn = symbol_get(mshv_pid_to_partid);
+ if (!fn)
+ return HV_PARTITION_ID_INVALID;
+
+ partid = fn(current->tgid);
+ symbol_put(mshv_pid_to_partid);
+
+ return partid;
+}
+
+/* If this is a VMM thread, then this domain is for a guest VM */
+static bool hv_curr_thread_is_vmm(void)
+{
+ return hv_iommu_get_curr_partid() != HV_PARTITION_ID_INVALID;
+}
+
+static bool hv_iommu_capable(struct device *dev, enum iommu_cap cap)
+{
+ switch (cap) {
+ case IOMMU_CAP_CACHE_COHERENCY:
+ return true;
+ default:
+ return false;
+ }
+ return false;
+}
+
+/*
+ * Check if given pci device is a direct attached device. Caller must have
+ * verified pdev is a valid pci device.
+ */
+bool hv_pcidev_is_attached_dev(struct pci_dev *pdev)
+{
+ struct iommu_domain *iommu_domain;
+ struct hv_domain *hvdom;
+ struct device *dev = &pdev->dev;
+
+ iommu_domain = iommu_get_domain_for_dev(dev);
+ if (iommu_domain) {
+ hvdom = to_hv_domain(iommu_domain);
+ return hvdom->attached_dom;
+ }
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(hv_pcidev_is_attached_dev);
+
+/* Create a new device domain in the hypervisor */
+static int hv_iommu_create_hyp_devdom(struct hv_domain *hvdom)
+{
+ u64 status;
+ unsigned long flags;
+ struct hv_input_device_domain *ddp;
+ struct hv_input_create_device_domain *input;
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ memset(input, 0, sizeof(*input));
+
+ ddp = &input->device_domain;
+ ddp->partition_id = HV_PARTITION_ID_SELF;
+ ddp->domain_id.type = HV_DEVICE_DOMAIN_TYPE_S2;
+ ddp->domain_id.id = hvdom->domid_num;
+
+ input->create_device_domain_flags.forward_progress_required = 1;
+ input->create_device_domain_flags.inherit_owning_vtl = 0;
+
+ status = hv_do_hypercall(HVCALL_CREATE_DEVICE_DOMAIN, input, NULL);
+
+ local_irq_restore(flags);
+
+ if (!hv_result_success(status))
+ hv_status_err(status, "\n");
+
+ return hv_result_to_errno(status);
+}
+
+/* During boot, all devices are attached to this */
+static struct iommu_domain *hv_iommu_domain_alloc_identity(struct device *dev)
+{
+ return &hv_def_identity_dom.iommu_dom;
+}
+
+static struct iommu_domain *hv_iommu_domain_alloc_paging(struct device *dev)
+{
+ struct hv_domain *hvdom;
+ int rc;
+
+ if (hv_l1vh_partition() && !hv_curr_thread_is_vmm() && !hv_no_attdev) {
+ pr_err("Hyper-V: l1vh iommu does not support host devices\n");
+ return NULL;
+ }
+
+ hvdom = kzalloc(sizeof(struct hv_domain), GFP_KERNEL);
+ if (hvdom == NULL)
+ goto out;
+
+ spin_lock_init(&hvdom->mappings_lock);
+ hvdom->mappings_tree = RB_ROOT_CACHED;
+
+ if (++unique_id == HV_DEVICE_DOMAIN_ID_S2_DEFAULT) /* ie, 0 */
+ goto out_free;
+
+ hvdom->domid_num = unique_id;
+ hvdom->iommu_dom.geometry = default_geometry;
+ hvdom->iommu_dom.pgsize_bitmap = HV_IOMMU_PGSIZES;
+
+ /* For guests, by default we do direct attaches, so no domain in hyp */
+ if (hv_curr_thread_is_vmm() && !hv_no_attdev)
+ hvdom->attached_dom = true;
+ else {
+ rc = hv_iommu_create_hyp_devdom(hvdom);
+ if (rc)
+ goto out_free_id;
+ }
+
+ return &hvdom->iommu_dom;
+
+out_free_id:
+ unique_id--;
+out_free:
+ kfree(hvdom);
+out:
+ return NULL;
+}
+
+static void hv_iommu_domain_free(struct iommu_domain *immdom)
+{
+ struct hv_domain *hvdom = to_hv_domain(immdom);
+ unsigned long flags;
+ u64 status;
+ struct hv_input_delete_device_domain *input;
+
+ if (hv_special_domain(hvdom))
+ return;
+
+ if (hvdom->num_attchd) {
+ pr_err("Hyper-V: can't free busy iommu domain (%p)\n", immdom);
+ return;
+ }
+
+ if (!hv_curr_thread_is_vmm() || hv_no_attdev) {
+ struct hv_input_device_domain *ddp;
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ ddp = &input->device_domain;
+ memset(input, 0, sizeof(*input));
+
+ ddp->partition_id = HV_PARTITION_ID_SELF;
+ ddp->domain_id.type = HV_DEVICE_DOMAIN_TYPE_S2;
+ ddp->domain_id.id = hvdom->domid_num;
+
+ status = hv_do_hypercall(HVCALL_DELETE_DEVICE_DOMAIN, input,
+ NULL);
+ local_irq_restore(flags);
+
+ if (!hv_result_success(status))
+ hv_status_err(status, "\n");
+ }
+
+ kfree(hvdom);
+}
+
+/* Attach a device to a domain previously created in the hypervisor */
+static int hv_iommu_att_dev2dom(struct hv_domain *hvdom, struct pci_dev *pdev)
+{
+ unsigned long flags;
+ u64 status;
+ enum hv_device_type dev_type;
+ struct hv_input_attach_device_domain *input;
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ memset(input, 0, sizeof(*input));
+
+ input->device_domain.partition_id = HV_PARTITION_ID_SELF;
+ input->device_domain.domain_id.type = HV_DEVICE_DOMAIN_TYPE_S2;
+ input->device_domain.domain_id.id = hvdom->domid_num;
+
+ /* NB: Upon guest shutdown, device is re-attached to the default domain
+ * without explicit detach.
+ */
+ if (hv_l1vh_partition())
+ dev_type = HV_DEVICE_TYPE_LOGICAL;
+ else
+ dev_type = HV_DEVICE_TYPE_PCI;
+
+ input->device_id.as_uint64 = hv_build_devid_oftype(pdev, dev_type);
+
+ status = hv_do_hypercall(HVCALL_ATTACH_DEVICE_DOMAIN, input, NULL);
+ local_irq_restore(flags);
+
+ if (!hv_result_success(status))
+ hv_status_err(status, "\n");
+
+ return hv_result_to_errno(status);
+}
+
+/* Caller must have validated that dev is a valid pci dev */
+static int hv_iommu_direct_attach_device(struct pci_dev *pdev)
+{
+ struct hv_input_attach_device *input;
+ u64 status;
+ int rc;
+ unsigned long flags;
+ union hv_device_id host_devid;
+ enum hv_device_type dev_type;
+ u64 ptid = hv_iommu_get_curr_partid();
+
+ if (ptid == HV_PARTITION_ID_INVALID) {
+ pr_err("Hyper-V: Invalid partition id in direct attach\n");
+ return -EINVAL;
+ }
+
+ if (hv_l1vh_partition())
+ dev_type = HV_DEVICE_TYPE_LOGICAL;
+ else
+ dev_type = HV_DEVICE_TYPE_PCI;
+
+ host_devid.as_uint64 = hv_build_devid_oftype(pdev, dev_type);
+
+ do {
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ memset(input, 0, sizeof(*input));
+ input->partition_id = ptid;
+ input->device_id = host_devid;
+
+ /* Hypervisor associates logical_id with this device, and in
+ * some hypercalls like retarget interrupts, logical_id must be
+ * used instead of the BDF. It is a required parameter.
+ */
+ input->attdev_flags.logical_id = 1;
+ input->logical_devid =
+ hv_build_devid_oftype(pdev, HV_DEVICE_TYPE_LOGICAL);
+
+ status = hv_do_hypercall(HVCALL_ATTACH_DEVICE, input, NULL);
+ local_irq_restore(flags);
+
+ if (hv_result(status) == HV_STATUS_INSUFFICIENT_MEMORY) {
+ rc = hv_call_deposit_pages(NUMA_NO_NODE, ptid, 1);
+ if (rc)
+ break;
+ }
+ } while (hv_result(status) == HV_STATUS_INSUFFICIENT_MEMORY);
+
+ if (!hv_result_success(status))
+ hv_status_err(status, "\n");
+
+ return hv_result_to_errno(status);
+}
+
+/* This to attach a device to both host app (like DPDK) and a guest VM */
+static int hv_iommu_attach_dev(struct iommu_domain *immdom, struct device *dev,
+ struct iommu_domain *old)
+{
+ struct pci_dev *pdev;
+ int rc;
+ struct hv_domain *hvdom_new = to_hv_domain(immdom);
+ struct hv_domain *hvdom_prev = dev_iommu_priv_get(dev);
+
+ /* Only allow PCI devices for now */
+ if (!dev_is_pci(dev))
+ return -EINVAL;
+
+ pdev = to_pci_dev(dev);
+
+ /* l1vh does not support host device (eg DPDK) passthru */
+ if (hv_l1vh_partition() && !hv_special_domain(hvdom_new) &&
+ !hvdom_new->attached_dom)
+ return -EINVAL;
+
+ /*
+ * VFIO does not do explicit detach calls, hence check first if we need
+ * to detach first. Also, in case of guest shutdown, it's the VMM
+ * thread that attaches it back to the hv_def_identity_dom, and
+ * hvdom_prev will not be null then. It is null during boot.
+ */
+ if (hvdom_prev)
+ if (!hv_l1vh_partition() || !hv_special_domain(hvdom_prev))
+ hv_iommu_detach_dev(&hvdom_prev->iommu_dom, dev);
+
+ if (hv_l1vh_partition() && hv_special_domain(hvdom_new)) {
+ dev_iommu_priv_set(dev, hvdom_new); /* sets "private" field */
+ return 0;
+ }
+
+ if (hvdom_new->attached_dom)
+ rc = hv_iommu_direct_attach_device(pdev);
+ else
+ rc = hv_iommu_att_dev2dom(hvdom_new, pdev);
+
+ if (rc && hvdom_prev) {
+ int rc1;
+
+ if (hvdom_prev->attached_dom)
+ rc1 = hv_iommu_direct_attach_device(pdev);
+ else
+ rc1 = hv_iommu_att_dev2dom(hvdom_prev, pdev);
+
+ if (rc1)
+ pr_err("Hyper-V: iommu could not restore orig device state.. dev:%s\n",
+ dev_name(dev));
+ }
+
+ if (rc == 0) {
+ dev_iommu_priv_set(dev, hvdom_new); /* sets "private" field */
+ hvdom_new->num_attchd++;
+ }
+
+ return rc;
+}
+
+static void hv_iommu_det_dev_from_guest(struct hv_domain *hvdom,
+ struct pci_dev *pdev)
+{
+ struct hv_input_detach_device *input;
+ u64 status, log_devid;
+ unsigned long flags;
+
+ log_devid = hv_build_devid_oftype(pdev, HV_DEVICE_TYPE_LOGICAL);
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ memset(input, 0, sizeof(*input));
+
+ input->partition_id = hv_iommu_get_curr_partid();
+ input->logical_devid = log_devid;
+ status = hv_do_hypercall(HVCALL_DETACH_DEVICE, input, NULL);
+ local_irq_restore(flags);
+
+ if (!hv_result_success(status))
+ hv_status_err(status, "\n");
+}
+
+static void hv_iommu_det_dev_from_dom(struct hv_domain *hvdom,
+ struct pci_dev *pdev)
+{
+ u64 status, devid;
+ unsigned long flags;
+ struct hv_input_detach_device_domain *input;
+
+ devid = hv_build_devid_oftype(pdev, HV_DEVICE_TYPE_PCI);
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ memset(input, 0, sizeof(*input));
+
+ input->partition_id = HV_PARTITION_ID_SELF;
+ input->device_id.as_uint64 = devid;
+ status = hv_do_hypercall(HVCALL_DETACH_DEVICE_DOMAIN, input, NULL);
+ local_irq_restore(flags);
+
+ if (!hv_result_success(status))
+ hv_status_err(status, "\n");
+}
+
+static void hv_iommu_detach_dev(struct iommu_domain *immdom, struct device *dev)
+{
+ struct pci_dev *pdev;
+ struct hv_domain *hvdom = to_hv_domain(immdom);
+
+ /* See the attach function, only PCI devices for now */
+ if (!dev_is_pci(dev))
+ return;
+
+ if (hvdom->num_attchd == 0)
+ pr_warn("Hyper-V: num_attchd is zero (%s)\n", dev_name(dev));
+
+ pdev = to_pci_dev(dev);
+
+ if (hvdom->attached_dom) {
+ hv_iommu_det_dev_from_guest(hvdom, pdev);
+
+ /* Do not reset attached_dom, hv_iommu_unmap_pages happens
+ * next.
+ */
+ } else {
+ hv_iommu_det_dev_from_dom(hvdom, pdev);
+ }
+
+ hvdom->num_attchd--;
+}
+
+static int hv_iommu_add_tree_mapping(struct hv_domain *hvdom,
+ unsigned long iova, phys_addr_t paddr,
+ size_t size, u32 flags)
+{
+ unsigned long irqflags;
+ struct hv_iommu_mapping *mapping;
+
+ mapping = kzalloc(sizeof(*mapping), GFP_ATOMIC);
+ if (!mapping)
+ return -ENOMEM;
+
+ mapping->paddr = paddr;
+ mapping->iova.start = iova;
+ mapping->iova.last = iova + size - 1;
+ mapping->flags = flags;
+
+ spin_lock_irqsave(&hvdom->mappings_lock, irqflags);
+ interval_tree_insert(&mapping->iova, &hvdom->mappings_tree);
+ spin_unlock_irqrestore(&hvdom->mappings_lock, irqflags);
+
+ return 0;
+}
+
+static size_t hv_iommu_del_tree_mappings(struct hv_domain *hvdom,
+ unsigned long iova, size_t size)
+{
+ unsigned long flags;
+ size_t unmapped = 0;
+ unsigned long last = iova + size - 1;
+ struct hv_iommu_mapping *mapping = NULL;
+ struct interval_tree_node *node, *next;
+
+ spin_lock_irqsave(&hvdom->mappings_lock, flags);
+ next = interval_tree_iter_first(&hvdom->mappings_tree, iova, last);
+ while (next) {
+ node = next;
+ mapping = container_of(node, struct hv_iommu_mapping, iova);
+ next = interval_tree_iter_next(node, iova, last);
+
+ /* Trying to split a mapping? Not supported for now. */
+ if (mapping->iova.start < iova)
+ break;
+
+ unmapped += mapping->iova.last - mapping->iova.start + 1;
+
+ interval_tree_remove(node, &hvdom->mappings_tree);
+ kfree(mapping);
+ }
+ spin_unlock_irqrestore(&hvdom->mappings_lock, flags);
+
+ return unmapped;
+}
+
+/* Return: must return exact status from the hypercall without changes */
+static u64 hv_iommu_map_pgs(struct hv_domain *hvdom,
+ unsigned long iova, phys_addr_t paddr,
+ unsigned long npages, u32 map_flags)
+{
+ u64 status;
+ int i;
+ struct hv_input_map_device_gpa_pages *input;
+ unsigned long flags, pfn = paddr >> HV_HYP_PAGE_SHIFT;
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ memset(input, 0, sizeof(*input));
+
+ input->device_domain.partition_id = HV_PARTITION_ID_SELF;
+ input->device_domain.domain_id.type = HV_DEVICE_DOMAIN_TYPE_S2;
+ input->device_domain.domain_id.id = hvdom->domid_num;
+ input->map_flags = map_flags;
+ input->target_device_va_base = iova;
+
+ pfn = paddr >> HV_HYP_PAGE_SHIFT;
+ for (i = 0; i < npages; i++, pfn++)
+ input->gpa_page_list[i] = pfn;
+
+ status = hv_do_rep_hypercall(HVCALL_MAP_DEVICE_GPA_PAGES, npages, 0,
+ input, NULL);
+
+ local_irq_restore(flags);
+ return status;
+}
+
+/*
+ * The core VFIO code loops over memory ranges calling this function with
+ * the largest size from HV_IOMMU_PGSIZES. cond_resched() is in vfio_iommu_map.
+ */
+static int hv_iommu_map_pages(struct iommu_domain *immdom, ulong iova,
+ phys_addr_t paddr, size_t pgsize, size_t pgcount,
+ int prot, gfp_t gfp, size_t *mapped)
+{
+ u32 map_flags;
+ int ret;
+ u64 status;
+ unsigned long npages, done = 0;
+ struct hv_domain *hvdom = to_hv_domain(immdom);
+ size_t size = pgsize * pgcount;
+
+ map_flags = HV_MAP_GPA_READABLE; /* required */
+ map_flags |= prot & IOMMU_WRITE ? HV_MAP_GPA_WRITABLE : 0;
+
+ ret = hv_iommu_add_tree_mapping(hvdom, iova, paddr, size, map_flags);
+ if (ret)
+ return ret;
+
+ if (hvdom->attached_dom) {
+ *mapped = size;
+ return 0;
+ }
+
+ npages = size >> HV_HYP_PAGE_SHIFT;
+ while (done < npages) {
+ ulong completed, remain = npages - done;
+
+ status = hv_iommu_map_pgs(hvdom, iova, paddr, remain,
+ map_flags);
+
+ completed = hv_repcomp(status);
+ done = done + completed;
+ iova = iova + (completed << HV_HYP_PAGE_SHIFT);
+ paddr = paddr + (completed << HV_HYP_PAGE_SHIFT);
+
+ if (hv_result(status) == HV_STATUS_INSUFFICIENT_MEMORY) {
+ ret = hv_call_deposit_pages(NUMA_NO_NODE,
+ hv_current_partition_id,
+ 256);
+ if (ret)
+ break;
+ }
+ if (!hv_result_success(status))
+ break;
+ }
+
+ if (!hv_result_success(status)) {
+ size_t done_size = done << HV_HYP_PAGE_SHIFT;
+
+ hv_status_err(status, "pgs:%lx/%lx iova:%lx\n",
+ done, npages, iova);
+ /*
+ * lookup tree has all mappings [0 - size-1]. Below unmap will
+ * only remove from [0 - done], we need to remove second chunk
+ * [done+1 - size-1].
+ */
+ hv_iommu_del_tree_mappings(hvdom, iova, size - done_size);
+ hv_iommu_unmap_pages(immdom, iova - done_size, pgsize,
+ done, NULL);
+ if (mapped)
+ *mapped = 0;
+ } else
+ if (mapped)
+ *mapped = size;
+
+ return hv_result_to_errno(status);
+}
+
+static size_t hv_iommu_unmap_pages(struct iommu_domain *immdom, ulong iova,
+ size_t pgsize, size_t pgcount,
+ struct iommu_iotlb_gather *gather)
+{
+ unsigned long flags, npages;
+ struct hv_input_unmap_device_gpa_pages *input;
+ u64 status;
+ struct hv_domain *hvdom = to_hv_domain(immdom);
+ size_t unmapped, size = pgsize * pgcount;
+
+ unmapped = hv_iommu_del_tree_mappings(hvdom, iova, size);
+ if (unmapped < size)
+ pr_err("%s: could not delete all mappings (%lx:%lx/%lx)\n",
+ __func__, iova, unmapped, size);
+
+ if (hvdom->attached_dom)
+ return size;
+
+ npages = size >> HV_HYP_PAGE_SHIFT;
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ memset(input, 0, sizeof(*input));
+
+ input->device_domain.partition_id = HV_PARTITION_ID_SELF;
+ input->device_domain.domain_id.type = HV_DEVICE_DOMAIN_TYPE_S2;
+ input->device_domain.domain_id.id = hvdom->domid_num;
+ input->target_device_va_base = iova;
+
+ status = hv_do_rep_hypercall(HVCALL_UNMAP_DEVICE_GPA_PAGES, npages,
+ 0, input, NULL);
+ local_irq_restore(flags);
+
+ if (!hv_result_success(status))
+ hv_status_err(status, "\n");
+
+ return unmapped;
+}
+
+static phys_addr_t hv_iommu_iova_to_phys(struct iommu_domain *immdom,
+ dma_addr_t iova)
+{
+ u64 paddr = 0;
+ unsigned long flags;
+ struct hv_iommu_mapping *mapping;
+ struct interval_tree_node *node;
+ struct hv_domain *hvdom = to_hv_domain(immdom);
+
+ spin_lock_irqsave(&hvdom->mappings_lock, flags);
+ node = interval_tree_iter_first(&hvdom->mappings_tree, iova, iova);
+ if (node) {
+ mapping = container_of(node, struct hv_iommu_mapping, iova);
+ paddr = mapping->paddr + (iova - mapping->iova.start);
+ }
+ spin_unlock_irqrestore(&hvdom->mappings_lock, flags);
+
+ return paddr;
+}
+
+/*
+ * Currently, hypervisor does not provide list of devices it is using
+ * dynamically. So use this to allow users to manually specify devices that
+ * should be skipped. (eg. hypervisor debugger using some network device).
+ */
+static struct iommu_device *hv_iommu_probe_device(struct device *dev)
+{
+ if (!dev_is_pci(dev))
+ return ERR_PTR(-ENODEV);
+
+ if (pci_devs_to_skip && *pci_devs_to_skip) {
+ int rc, pos = 0;
+ int parsed;
+ int segment, bus, slot, func;
+ struct pci_dev *pdev = to_pci_dev(dev);
+
+ do {
+ parsed = 0;
+
+ rc = sscanf(pci_devs_to_skip + pos, " (%x:%x:%x.%x) %n",
+ &segment, &bus, &slot, &func, &parsed);
+ if (rc)
+ break;
+ if (parsed <= 0)
+ break;
+
+ if (pci_domain_nr(pdev->bus) == segment &&
+ pdev->bus->number == bus &&
+ PCI_SLOT(pdev->devfn) == slot &&
+ PCI_FUNC(pdev->devfn) == func) {
+
+ dev_info(dev, "skipped by Hyper-V IOMMU\n");
+ return ERR_PTR(-ENODEV);
+ }
+ pos += parsed;
+
+ } while (pci_devs_to_skip[pos]);
+ }
+
+ /* Device will be explicitly attached to the default domain, so no need
+ * to do dev_iommu_priv_set() here.
+ */
+
+ return &hv_virt_iommu;
+}
+
+static void hv_iommu_probe_finalize(struct device *dev)
+{
+ struct iommu_domain *immdom = iommu_get_domain_for_dev(dev);
+
+ if (immdom && immdom->type == IOMMU_DOMAIN_DMA)
+ iommu_setup_dma_ops(dev);
+ else
+ set_dma_ops(dev, NULL);
+}
+
+static void hv_iommu_release_device(struct device *dev)
+{
+ struct hv_domain *hvdom = dev_iommu_priv_get(dev);
+
+ /* Need to detach device from device domain if necessary. */
+ if (hvdom)
+ hv_iommu_detach_dev(&hvdom->iommu_dom, dev);
+
+ dev_iommu_priv_set(dev, NULL);
+ set_dma_ops(dev, NULL);
+}
+
+static struct iommu_group *hv_iommu_device_group(struct device *dev)
+{
+ if (dev_is_pci(dev))
+ return pci_device_group(dev);
+ else
+ return generic_device_group(dev);
+}
+
+static int hv_iommu_def_domain_type(struct device *dev)
+{
+ /* The hypervisor always creates this by default during boot */
+ return IOMMU_DOMAIN_IDENTITY;
+}
+
+static struct iommu_ops hv_iommu_ops = {
+ .capable = hv_iommu_capable,
+ .domain_alloc_identity = hv_iommu_domain_alloc_identity,
+ .domain_alloc_paging = hv_iommu_domain_alloc_paging,
+ .probe_device = hv_iommu_probe_device,
+ .probe_finalize = hv_iommu_probe_finalize,
+ .release_device = hv_iommu_release_device,
+ .def_domain_type = hv_iommu_def_domain_type,
+ .device_group = hv_iommu_device_group,
+ .default_domain_ops = &(const struct iommu_domain_ops) {
+ .attach_dev = hv_iommu_attach_dev,
+ .map_pages = hv_iommu_map_pages,
+ .unmap_pages = hv_iommu_unmap_pages,
+ .iova_to_phys = hv_iommu_iova_to_phys,
+ .free = hv_iommu_domain_free,
+ },
+ .owner = THIS_MODULE,
+};
+
+static void __init hv_initialize_special_domains(void)
+{
+ hv_def_identity_dom.iommu_dom.geometry = default_geometry;
+ hv_def_identity_dom.domid_num = HV_DEVICE_DOMAIN_ID_S2_DEFAULT; /* 0 */
+}
+
+static int __init hv_iommu_init(void)
+{
+ int ret;
+ struct iommu_device *iommup = &hv_virt_iommu;
+
+ if (!hv_is_hyperv_initialized())
+ return -ENODEV;
+
+ ret = iommu_device_sysfs_add(iommup, NULL, NULL, "%s", "hyperv-iommu");
+ if (ret) {
+ pr_err("Hyper-V: iommu_device_sysfs_add failed: %d\n", ret);
+ return ret;
+ }
+
+ /* This must come before iommu_device_register because the latter calls
+ * into the hooks.
+ */
+ hv_initialize_special_domains();
+
+ ret = iommu_device_register(iommup, &hv_iommu_ops, NULL);
+ if (ret) {
+ pr_err("Hyper-V: iommu_device_register failed: %d\n", ret);
+ goto err_sysfs_remove;
+ }
+
+ pr_info("Hyper-V IOMMU initialized\n");
+
+ return 0;
+
+err_sysfs_remove:
+ iommu_device_sysfs_remove(iommup);
+ return ret;
+}
+
+void __init hv_iommu_detect(void)
+{
+ if (no_iommu || iommu_detected)
+ return;
+
+ /* For l1vh, always expose an iommu unit */
+ if (!hv_l1vh_partition())
+ if (!(ms_hyperv.misc_features & HV_DEVICE_DOMAIN_AVAILABLE))
+ return;
+
+ iommu_detected = 1;
+ x86_init.iommu.iommu_init = hv_iommu_init;
+
+ pci_request_acs();
+}
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index dfc516c1c719..2ad111727e82 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1767,4 +1767,10 @@ static inline unsigned long virt_to_hvpfn(void *addr)
#define HVPFN_DOWN(x) ((x) >> HV_HYP_PAGE_SHIFT)
#define page_to_hvpfn(page) (page_to_pfn(page) * NR_HV_HYP_PAGES_IN_PAGE)
+#ifdef CONFIG_HYPERV_IOMMU
+void __init hv_iommu_detect(void);
+#else
+static inline void hv_iommu_detect(void) { }
+#endif /* CONFIG_HYPERV_IOMMU */
+
#endif /* _HYPERV_H */
--
2.51.2.vfs.0.1
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 19 Jan 2026 22:42:27 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:21PM -0800, Mukesh R wrote:
There is a Linux standard for giving credits when code is adapted from.
This doesn't follow that standard. Please fix.
This put must be sync as device must be detached from domain before
attempting partition destruction.
This was explicitly mentioned in the patch originated this code.
Please fix, add a comment and credits to the commit message.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 08:09:02 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:22PM -0800, Mukesh R wrote:
Shouldn't the partition be put here?
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 08:13:55 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
Hi Mukesh,
kernel test robot noticed the following build errors:
[auto build test ERROR on tip/x86/core]
[also build test ERROR on pci/next pci/for-linus arm64/for-next/core clk/clk-next soc/for-next linus/master arnd-asm-generic/master v6.19-rc6 next-20260119]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Mukesh-R/iommu-hyperv-rename-hyperv-iommu-c-to-hyperv-irq-c/20260120-145832
base: tip/x86/core
patch link: https://lore.kernel.org/r/20260120064230.3602565-2-mrathor%40linux.microsoft.com
patch subject: [PATCH v0 01/15] iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
config: i386-randconfig-001-20260120 (https://download.01.org/0day-ci/archive/20260121/202601210208.mg3YUkif-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260121/202601210208.mg3YUkif-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601210208.mg3YUkif-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from drivers/acpi/pci_root.c:20:
269 | __u128 irte;
| ^~~~~~
| __u32
Kconfig warnings: (for reference only)
WARNING: unmet direct dependencies detected for IRQ_REMAP
Depends on [n]: IOMMU_SUPPORT [=y] && X86_64 [=n] && X86_IO_APIC [=y] && PCI_MSI [=n] && ACPI [=y]
Selected by [y]:
- HYPERV_IOMMU [=y] && IOMMU_SUPPORT [=y] && HYPERV [=y] && X86 [=y]
vim +269 include/linux/dmar.h
2ae21010694e56 Suresh Siddha 2008-07-10 200
2ae21010694e56 Suresh Siddha 2008-07-10 201 struct irte {
b1fe7f2cda2a00 Peter Zijlstra 2023-05-31 202 union {
b1fe7f2cda2a00 Peter Zijlstra 2023-05-31 203 struct {
2ae21010694e56 Suresh Siddha 2008-07-10 204 union {
3bf17472226b00 Thomas Gleixner 2015-06-09 205 /* Shared between remapped and posted mode*/
2ae21010694e56 Suresh Siddha 2008-07-10 206 struct {
3bf17472226b00 Thomas Gleixner 2015-06-09 207 __u64 present : 1, /* 0 */
3bf17472226b00 Thomas Gleixner 2015-06-09 208 fpd : 1, /* 1 */
3bf17472226b00 Thomas Gleixner 2015-06-09 209 __res0 : 6, /* 2 - 6 */
3bf17472226b00 Thomas Gleixner 2015-06-09 210 avail : 4, /* 8 - 11 */
3bf17472226b00 Thomas Gleixner 2015-06-09 211 __res1 : 3, /* 12 - 14 */
3bf17472226b00 Thomas Gleixner 2015-06-09 212 pst : 1, /* 15 */
3bf17472226b00 Thomas Gleixner 2015-06-09 213 vector : 8, /* 16 - 23 */
3bf17472226b00 Thomas Gleixner 2015-06-09 214 __res2 : 40; /* 24 - 63 */
3bf17472226b00 Thomas Gleixner 2015-06-09 215 };
3bf17472226b00 Thomas Gleixner 2015-06-09 216
3bf17472226b00 Thomas Gleixner 2015-06-09 217 /* Remapped mode */
3bf17472226b00 Thomas Gleixner 2015-06-09 218 struct {
3bf17472226b00 Thomas Gleixner 2015-06-09 219 __u64 r_present : 1, /* 0 */
3bf17472226b00 Thomas Gleixner 2015-06-09 220 r_fpd : 1, /* 1 */
3bf17472226b00 Thomas Gleixner 2015-06-09 221 dst_mode : 1, /* 2 */
3bf17472226b00 Thomas Gleixner 2015-06-09 222 redir_hint : 1, /* 3 */
3bf17472226b00 Thomas Gleixner 2015-06-09 223 trigger_mode : 1, /* 4 */
3bf17472226b00 Thomas Gleixner 2015-06-09 224 dlvry_mode : 3, /* 5 - 7 */
3bf17472226b00 Thomas Gleixner 2015-06-09 225 r_avail : 4, /* 8 - 11 */
3bf17472226b00 Thomas Gleixner 2015-06-09 226 r_res0 : 4, /* 12 - 15 */
3bf17472226b00 Thomas Gleixner 2015-06-09 227 r_vector : 8, /* 16 - 23 */
3bf17472226b00 Thomas Gleixner 2015-06-09 228 r_res1 : 8, /* 24 - 31 */
3bf17472226b00 Thomas Gleixner 2015-06-09 229 dest_id : 32; /* 32 - 63 */
3bf17472226b00 Thomas Gleixner 2015-06-09 230 };
3bf17472226b00 Thomas Gleixner 2015-06-09 231
3bf17472226b00 Thomas Gleixner 2015-06-09 232 /* Posted mode */
3bf17472226b00 Thomas Gleixner 2015-06-09 233 struct {
3bf17472226b00 Thomas Gleixner 2015-06-09 234 __u64 p_present : 1, /* 0 */
3bf17472226b00 Thomas Gleixner 2015-06-09 235 p_fpd : 1, /* 1 */
3bf17472226b00 Thomas Gleixner 2015-06-09 236 p_res0 : 6, /* 2 - 7 */
3bf17472226b00 Thomas Gleixner 2015-06-09 237 p_avail : 4, /* 8 - 11 */
3bf17472226b00 Thomas Gleixner 2015-06-09 238 p_res1 : 2, /* 12 - 13 */
3bf17472226b00 Thomas Gleixner 2015-06-09 239 p_urgent : 1, /* 14 */
3bf17472226b00 Thomas Gleixner 2015-06-09 240 p_pst : 1, /* 15 */
3bf17472226b00 Thomas Gleixner 2015-06-09 241 p_vector : 8, /* 16 - 23 */
3bf17472226b00 Thomas Gleixner 2015-06-09 242 p_res2 : 14, /* 24 - 37 */
3bf17472226b00 Thomas Gleixner 2015-06-09 243 pda_l : 26; /* 38 - 63 */
2ae21010694e56 Suresh Siddha 2008-07-10 244 };
2ae21010694e56 Suresh Siddha 2008-07-10 245 __u64 low;
2ae21010694e56 Suresh Siddha 2008-07-10 246 };
2ae21010694e56 Suresh Siddha 2008-07-10 247
2ae21010694e56 Suresh Siddha 2008-07-10 248 union {
3bf17472226b00 Thomas Gleixner 2015-06-09 249 /* Shared between remapped and posted mode*/
2ae21010694e56 Suresh Siddha 2008-07-10 250 struct {
3bf17472226b00 Thomas Gleixner 2015-06-09 251 __u64 sid : 16, /* 64 - 79 */
3bf17472226b00 Thomas Gleixner 2015-06-09 252 sq : 2, /* 80 - 81 */
3bf17472226b00 Thomas Gleixner 2015-06-09 253 svt : 2, /* 82 - 83 */
3bf17472226b00 Thomas Gleixner 2015-06-09 254 __res3 : 44; /* 84 - 127 */
3bf17472226b00 Thomas Gleixner 2015-06-09 255 };
3bf17472226b00 Thomas Gleixner 2015-06-09 256
3bf17472226b00 Thomas Gleixner 2015-06-09 257 /* Posted mode*/
3bf17472226b00 Thomas Gleixner 2015-06-09 258 struct {
3bf17472226b00 Thomas Gleixner 2015-06-09 259 __u64 p_sid : 16, /* 64 - 79 */
3bf17472226b00 Thomas Gleixner 2015-06-09 260 p_sq : 2, /* 80 - 81 */
3bf17472226b00 Thomas Gleixner 2015-06-09 261 p_svt : 2, /* 82 - 83 */
3bf17472226b00 Thomas Gleixner 2015-06-09 262 p_res3 : 12, /* 84 - 95 */
3bf17472226b00 Thomas Gleixner 2015-06-09 263 pda_h : 32; /* 96 - 127 */
2ae21010694e56 Suresh Siddha 2008-07-10 264 };
2ae21010694e56 Suresh Siddha 2008-07-10 265 __u64 high;
2ae21010694e56 Suresh Siddha 2008-07-10 266 };
2ae21010694e56 Suresh Siddha 2008-07-10 267 };
b1fe7f2cda2a00 Peter Zijlstra 2023-05-31 268 #ifdef CONFIG_IRQ_REMAP
b1fe7f2cda2a00 Peter Zijlstra 2023-05-31 @269 __u128 irte;
b1fe7f2cda2a00 Peter Zijlstra 2023-05-31 270 #endif
b1fe7f2cda2a00 Peter Zijlstra 2023-05-31 271 };
b1fe7f2cda2a00 Peter Zijlstra 2023-05-31 272 };
423f085952fd72 Thomas Gleixner 2010-10-10 273
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
|
{
"author": "kernel test robot <lkp@intel.com>",
"date": "Wed, 21 Jan 2026 03:08:24 +0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
Hi Mukesh,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tip/x86/core]
[also build test WARNING on pci/next pci/for-linus arm64/for-next/core soc/for-next linus/master v6.19-rc6]
[cannot apply to clk/clk-next arnd-asm-generic/master next-20260119]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Mukesh-R/iommu-hyperv-rename-hyperv-iommu-c-to-hyperv-irq-c/20260120-145832
base: tip/x86/core
patch link: https://lore.kernel.org/r/20260120064230.3602565-16-mrathor%40linux.microsoft.com
patch subject: [PATCH v0 15/15] mshv: Populate mmio mappings for PCI passthru
config: x86_64-randconfig-003-20260120 (https://download.01.org/0day-ci/archive/20260121/202601210255.2ZZOLtMV-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260121/202601210255.2ZZOLtMV-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601210255.2ZZOLtMV-lkp@intel.com/
All warnings (new ones prefixed by >>):
60 | static int __init setup_hv_full_mmio(char *str)
| ^~~~~~~~~~~~~~~~~~
vim +/setup_hv_full_mmio +60 drivers/hv/mshv_root_main.c
58
59 bool hv_nofull_mmio; /* don't map entire mmio region upon fault */
> 60 static int __init setup_hv_full_mmio(char *str)
61 {
62 hv_nofull_mmio = true;
63 return 0;
64 }
65 __setup("hv_nofull_mmio", setup_hv_full_mmio);
66
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
|
{
"author": "kernel test robot <lkp@intel.com>",
"date": "Wed, 21 Jan 2026 03:52:58 +0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
Hi Mukesh,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tip/x86/core]
[also build test WARNING on pci/next pci/for-linus arm64/for-next/core clk/clk-next soc/for-next linus/master arnd-asm-generic/master v6.19-rc6 next-20260120]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Mukesh-R/iommu-hyperv-rename-hyperv-iommu-c-to-hyperv-irq-c/20260120-145832
base: tip/x86/core
patch link: https://lore.kernel.org/r/20260120064230.3602565-2-mrathor%40linux.microsoft.com
patch subject: [PATCH v0 01/15] iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
config: i386-allmodconfig (https://download.01.org/0day-ci/archive/20260121/202601210423.wwOrf2K8-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260121/202601210423.wwOrf2K8-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601210423.wwOrf2K8-lkp@intel.com/
All warnings (new ones prefixed by >>):
In file included from drivers/iommu/intel/irq_remapping.c:6:
include/linux/dmar.h:269:17: error: unknown type name '__u128'; did you mean '__u32'?
269 | __u128 irte;
| ^~~~~~
| __u32
drivers/iommu/intel/irq_remapping.c: In function 'modify_irte':
drivers/iommu/intel/irq_remapping.c:181:17: error: unknown type name 'u128'
181 | u128 old = irte->irte;
| ^~~~
In file included from arch/x86/include/asm/bug.h:193,
from arch/x86/include/asm/alternative.h:9,
from arch/x86/include/asm/barrier.h:5,
from include/asm-generic/bitops/generic-non-atomic.h:7,
from include/linux/bitops.h:28,
from include/linux/kernel.h:23,
from include/linux/interrupt.h:6,
from drivers/iommu/intel/irq_remapping.c:5:
include/linux/atomic/atomic-arch-fallback.h:326:14: error: void value not ignored as it ought to be
326 | ___r = raw_cmpxchg128((_ptr), ___o, (_new)); \
| ^
include/asm-generic/bug.h:110:32: note: in definition of macro 'WARN_ON'
110 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
include/linux/atomic/atomic-instrumented.h:4956:9: note: in expansion of macro 'raw_try_cmpxchg128'
4956 | raw_try_cmpxchg128(__ai_ptr, __ai_oldp, __VA_ARGS__); \
| ^~~~~~~~~~~~~~~~~~
drivers/iommu/intel/irq_remapping.c:182:26: note: in expansion of macro 'try_cmpxchg128'
182 | WARN_ON(!try_cmpxchg128(&irte->irte, &old, irte_modified->irte));
| ^~~~~~~~~~~~~~
drivers/iommu/intel/irq_remapping.c: In function 'intel_ir_set_vcpu_affinity':
1270 | ~(-1UL << PDA_HIGH_BIT);
| ^~
Kconfig warnings: (for reference only)
WARNING: unmet direct dependencies detected for IRQ_REMAP
Depends on [n]: IOMMU_SUPPORT [=y] && X86_64 [=n] && X86_IO_APIC [=y] && PCI_MSI [=y] && ACPI [=y]
Selected by [y]:
- HYPERV_IOMMU [=y] && IOMMU_SUPPORT [=y] && HYPERV [=y] && X86 [=y]
vim +1270 drivers/iommu/intel/irq_remapping.c
b106ee63abccbba drivers/iommu/intel_irq_remapping.c Jiang Liu 2015-04-13 1241
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1242 static int intel_ir_set_vcpu_affinity(struct irq_data *data, void *info)
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1243 {
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1244 struct intel_ir_data *ir_data = data->chip_data;
53527ea1b70224d drivers/iommu/intel/irq_remapping.c Sean Christopherson 2025-06-11 1245 struct intel_iommu_pi_data *pi_data = info;
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1246
ed1e48ea4370300 drivers/iommu/intel/irq_remapping.c Jacob Pan 2024-04-23 1247 /* stop posting interrupts, back to the default mode */
53527ea1b70224d drivers/iommu/intel/irq_remapping.c Sean Christopherson 2025-06-11 1248 if (!pi_data) {
2454823e97a63d8 drivers/iommu/intel/irq_remapping.c Sean Christopherson 2025-03-19 1249 __intel_ir_reconfigure_irte(data, true);
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1250 } else {
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1251 struct irte irte_pi;
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1252
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1253 /*
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1254 * We are not caching the posted interrupt entry. We
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1255 * copy the data from the remapped entry and modify
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1256 * the fields which are relevant for posted mode. The
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1257 * cached remapped entry is used for switching back to
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1258 * remapped mode.
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1259 */
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1260 memset(&irte_pi, 0, sizeof(irte_pi));
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1261 dmar_copy_shared_irte(&irte_pi, &ir_data->irte_entry);
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1262
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1263 /* Update the posted mode fields */
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1264 irte_pi.p_pst = 1;
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1265 irte_pi.p_urgent = 0;
53527ea1b70224d drivers/iommu/intel/irq_remapping.c Sean Christopherson 2025-06-11 1266 irte_pi.p_vector = pi_data->vector;
53527ea1b70224d drivers/iommu/intel/irq_remapping.c Sean Christopherson 2025-06-11 1267 irte_pi.pda_l = (pi_data->pi_desc_addr >>
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1268 (32 - PDA_LOW_BIT)) & ~(-1UL << PDA_LOW_BIT);
53527ea1b70224d drivers/iommu/intel/irq_remapping.c Sean Christopherson 2025-06-11 1269 irte_pi.pda_h = (pi_data->pi_desc_addr >> 32) &
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 @1270 ~(-1UL << PDA_HIGH_BIT);
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1271
688124cc541f60d drivers/iommu/intel/irq_remapping.c Sean Christopherson 2025-03-19 1272 ir_data->irq_2_iommu.posted_vcpu = true;
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1273 modify_irte(&ir_data->irq_2_iommu, &irte_pi);
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1274 }
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1275
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1276 return 0;
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1277 }
8541186faf3b596 drivers/iommu/intel_irq_remapping.c Feng Wu 2015-06-09 1278
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
|
{
"author": "kernel test robot <lkp@intel.com>",
"date": "Wed, 21 Jan 2026 05:09:48 +0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
Hi Mukesh,
On Mon, 19 Jan 2026 22:42:15 -0800
Mukesh R <mrathor@linux.microsoft.com> wrote:
I think some introduction/background to L1VH would help.
It may be clearer to state that the hypervisor supports Linux IOMMU
paging domains through map/unmap hypercalls, mapping GPAs to HPAs using
stage‑2 I/O page tables.
This may warrant introducing a new IOMMU domain feature flag, as it
performs mappings but does not support map/unmap semantics in the same
way as a paging domain.
|
{
"author": "Jacob Pan <jacob.pan@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 13:50:32 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:24PM -0800, Mukesh R wrote:
<snip>
Shouldn't the inner struct be packed instead?
Why should the union be packed?
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 14:17:24 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:25PM -0800, Mukesh R wrote:
Why not moving this static function definition above the called instead of
defining the prototype?
This variable is redundant.
It looks like this value always fits into 32 bit, so what is the value
in returning 64 bit?
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 14:22:23 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:26PM -0800, Mukesh R wrote:
Should this one be renamed into hv_build_devid_type_vmbus() to align
with the other two function names?
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 14:27:33 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:27PM -0800, Mukesh R wrote:
<snip>
The return above is never reached.
hvdom varaible is redundant.
Why goto here and not return NULL like above?
Shouldn't this be modified iff the detach succeeded?
There is some inconsistency in namings and behaviour of paired
functions:
1. The pair of hv_iommu_unmap_pages is called hv_iommu_map_pgs
2. hv_iommu_map_pgs doesn't print status in case of error.
It would be much better to keep this code consistent.
hv_def_identity_dom is a static global variable.
Why not initialize hv_def_identity_dom upon definition instead of
introducing a new function?
It looks weird to initialize an object after creating sysfs entries for
it.
It should be the other way around.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 16:12:42 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:28PM -0800, Mukesh R wrote:
l1vh and root are mutually exclusive partitions.
If you wanted to highlight that it's l1vh itself and not its child guest, then
"l1vh parent" term would do.
Looks like the only special case is for attached logical devices,
otherwise hv_current_partition_id is used.
Can the logic simplified here?
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 16:47:07 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
Hi Mukesh,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tip/x86/core]
[also build test WARNING on pci/next pci/for-linus arm64/for-next/core clk/clk-next soc/for-next linus/master v6.19-rc6 next-20260120]
[cannot apply to arnd-asm-generic/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Mukesh-R/iommu-hyperv-rename-hyperv-iommu-c-to-hyperv-irq-c/20260120-145832
base: tip/x86/core
patch link: https://lore.kernel.org/r/20260120064230.3602565-4-mrathor%40linux.microsoft.com
patch subject: [PATCH v0 03/15] x86/hyperv: add insufficient memory support in irqdomain.c
config: i386-randconfig-053-20260120 (https://download.01.org/0day-ci/archive/20260121/202601210731.f1WLdgcO-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601210731.f1WLdgcO-lkp@intel.com/
cocci warnings: (new ones prefixed by >>)
vim +90 arch/x86/hyperv/irqdomain.c
72
73 static int hv_map_interrupt(u64 ptid, union hv_device_id device_id, bool level,
74 int cpu, int vector,
75 struct hv_interrupt_entry *ret_entry)
76 {
77 u64 status;
78 int rc, deposit_pgs = 16; /* don't loop forever */
79
80 while (deposit_pgs--) {
81 status = hv_map_interrupt_hcall(ptid, device_id, level, cpu,
82 vector, ret_entry);
83
84 if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY)
85 break;
86
87 rc = hv_call_deposit_pages(NUMA_NO_NODE, ptid, 1);
88 if (rc)
89 break;
> 90 };
91
92 if (!hv_result_success(status))
93 hv_status_err(status, "\n");
94
95 return hv_result_to_errno(status);
96 }
97
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
|
{
"author": "kernel test robot <lkp@intel.com>",
"date": "Wed, 21 Jan 2026 08:53:50 +0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:29PM -0800, Mukesh R wrote:
No need updating ret here: it's 0 after the previous call.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 17:41:39 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:30PM -0800, Mukesh R wrote:
Semaphore can't be taken under spinlock.
Get it instead.
Why this check is needed again?
The region type is stored on the region itself.
And the type is checked on the caller side.
This call needs to be protected by the spinlock.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 20 Jan 2026 17:53:29 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
Hi Mukesh,
On Mon, 19 Jan 2026 22:42:27 -0800
Mukesh R <mrathor@linux.microsoft.com> wrote:
Given we are also developing a guest iommu driver on hyperv, I think it
is more clear to name them accordingly. Perhaps, hyperv-iommu-root.c?
Will this driver be x86 only?
DMA and IRQ remapping should be separate
I don't think this is needed since this driver cannot be a module
should not depend on Intel's DMAR
rename to num_dev_attached?
This function is not iommu specific. Maybe move it to mshv code?
Attached domain can change anytime, what guarantee does the caller have?
nit: use consistent coding style, inverse Christmas tree.
why is this an error if user input choose not to do direct attach?
This is true only when unique_id wraps around, right? Then this driver
stops working?
can you use an IDR for the unique_id and free it as you detach instead
of doing this cyclic allocation?
you could free the domid here, no?
The IOMMU driver should be agnostic to the type of consumer, whether a
userspace driver or a VM. This comment is not necessary.
This does not match upstream kernel prototype, which kernel version is
this based on? I will stop here for now.
struct iommu_domain_ops {
int (*attach_dev)(struct iommu_domain *domain, struct device
*dev);
This could be initialized statically.
|
{
"author": "Jacob Pan <jacob.pan@linux.microsoft.com>",
"date": "Wed, 21 Jan 2026 21:18:06 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/19/2026 10:42 PM, Mukesh R wrote:
This should go inside the #if IS_ENABLED(CONFIG_MSHV_ROOT) section.
|
{
"author": "Nuno Das Neves <nunodasneves@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 10:23:04 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/19/2026 10:42 PM, Mukesh R wrote:
With this commit, the IOCTL number is exposed to userspace but it doesn't work.
Ideally the IOCTL number should be added in the commit where it becomes usable.
|
{
"author": "Nuno Das Neves <nunodasneves@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 10:25:36 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/19/2026 10:42 PM, Mukesh R wrote:
Since the code is very similar to Wei's original commit, the way I'd
recommend to do it is:
1. Change the commit author to Wei, using git commit --amend --author=
and
2. Put his signed-off line before yours:
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
This shows he is the author of the commit but you ported it.
If you feel you changed it enough that it should be considered
co-authored, you can instead keep your authorship of the commit and
put:
Co-developed-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
|
{
"author": "Nuno Das Neves <nunodasneves@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 10:32:09 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/19/2026 10:42 PM, Mukesh R wrote:
What is the reason for having this as a separate commit from patch 15?
It seems like removing this code and adding the mmio intercept
handling could be done in one patch.
|
{
"author": "Nuno Das Neves <nunodasneves@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 10:34:55 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/23/26 10:25, Nuno Das Neves wrote:
Correct, I switched it because the next patch won't compile without it as
it needs the declarations here. It could be combined into one big patch,
but I think normally one would not expect full functionality until the
release is certified to be that feature compliant anyways. Hope that
makes sense.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 16:36:28 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/23/26 10:32, Nuno Das Neves wrote:
Perfect! Thank you, that is exactly the information I was trying to
seek... makes sense.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 16:37:34 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/20/26 14:17, Stanislav Kinsburskii wrote:
From GCC docs:
Specifying this attribute for struct and union types is equivalent to
specifying the packed attribute on each of the structure or union members.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 16:38:56 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/20/26 14:22, Stanislav Kinsburskii wrote:
Did you see the function implementation? It has other dependencies that
are later, it would need code reorg.
Thanks,
-Mukesh
Not really. It helps with debug by putting a quick print, and is
harmless.
The ABI has device id defined as 64bits where this is assigned.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 16:42:54 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/20/26 14:27, Stanislav Kinsburskii wrote:
No, because hyperv only defines two types of device ids, and it would
unnecessary at to confusion. vmbus uses one the two types of device
ids.
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 16:44:01 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/20/26 16:12, Stanislav Kinsburskii wrote:
Some debug code there got removed. Will fix in next version.
We want to still free the domain and not let it get stuck. The purpose
is more to make sure detach was called before domain free.
The pair of hv_iommu_unmap_pages is hv_iommu_map_pages right above.
hv_iommu_map_pgs could be renamed to hv_iommu_map_pgs_hcall I suppose.
it does:
hv_status_err(status, "\n"); <==============
Originally, it was function. I changed it static, but during 6.6
review I changed it back to function. I can't remember why, but is
pretty harmless. We may add more domains, for example null domain to the
initilization in future.
Not sure if it should be, much easier to remove sysfs entry than other
cleanup, even tho iommu_device_unregister is there. I am sure we'll add
more code here, probably why it was originally done this way.
Thanks,
-Mukesh
... snip........
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 17:26:19 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/21/26 21:18, Jacob Pan wrote:
well, l1vh is not quite root, more like a parent. But we've been using
l1vh root loosely to mean l1vh parent. so probably ok to rename it
to hyperv-iommu-root.c. I prefer not calling it parent or something
like that.
j
Yes for now.
not sure i follow.
Well, it is getting the information from mshv by calling a function
there for iommu, and is not needed if no HYPER_IOMMU. So this is probably
the best place for it.
Not sure I understand what can change: the device moving from attached
to non-attached? or the domain getting deleted? In any case, this is
called from leaf functions, so that should not happen... and it
will return false if the device did somehow got removed.
Like the error message says: on l1vh, direct attaches of host devices
(eg dpdk) is not supported. and l1vh only does direct attaches. IOW,
no host devices on l1vh.
Correct. It's a u32, so if my math is right, and a device is attached
every second, it will take 136 years to wrap! Did i get that right?
sorry, don't follow what you mean by domid, you mean unique_id?
As I mentioned in the cover letter:
Based on: 8f0b4cce4481 (origin/hyperv-next)
which is now 6.19 based.
I think you got it backwards, 6.6 has this. 6.19 has extra paremeter.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 18:01:29 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/20/26 16:47, Stanislav Kinsburskii wrote:
We've been loosely using "l1vh root" to mean "privilated l1vh" as opposed
to l1vh guests. I think that is fine. l1vh parent is confusing, as it may
also refer to l1vh parent, which would be the host. so as long as the
context is clear, we are ok.
Could be, but at the cost of clear upfront clarity. this nicely tells
the reader that a logical ID has different cases, where as PCI
does not. End instructions are the same.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 18:08:49 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/23/26 10:34, Nuno Das Neves wrote:
Just ease of review and porting patches from this branch to that
branch to that release to this release... I am sure someone would
have asked for this to be a separate patch :).
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 18:12:14 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/20/26 17:53, Stanislav Kinsburskii wrote:
Yeah, something didn't feel right here and I meant to recheck, now regret
rushing to submit the patch.
Rethinking, I think the pt_mem_regions_lock is not needed to protect
the uaddr because unmap will properly serialize via the mm lock.
To make sure region did not change. This check is under lock.
This is sorta fast path to bail. We recheck under partition lock above.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 18:19:15 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/20/26 13:50, Jacob Pan wrote:
Ok, i can add something, but l1vh was very well introduced if you
search the mshv commits for "l1vh".
sure.
Yeah, I was hoping we can get by for now without it. At least in case of
the cloud hypervisor, entire guest ram is mapped anyways. We can document
it and work on enhancements which are much easier once we have a baseline.
For now, it's a paging domain will all pages pinned.. :).
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 23 Jan 2026 18:27:34 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Fri, Jan 23, 2026 at 05:26:19PM -0800, Mukesh R wrote:
<snip>
How can one debug subseqent errors if num_attchd is decremented
unconditionally? In reality the device is left attached, but the related
kernel metadata is gone.
Hv_iommu_map_pages is a wrapper around hv_iommu_map_pgs while
hv_iommu_unmap_pages is a wrapper around the correspodning hypercall.
That's the inconsistency I meant.
It does not. I guess you are confusing it with some other function.
Here is the function:
Sysfs provides user space access to kernel objects. If the object is not
initialized, it's not only a useless sysfs entry, but also a potential
cause for kernel panic if user space will try to access this entry
before the object is initialized.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Mon, 26 Jan 2026 07:57:35 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Fri, Jan 23, 2026 at 06:19:15PM -0800, Mukesh R wrote:
How can this happen? One can't change VMA type without unmapping it
first. And unmapping it leads to a kernel MMIO region state dangling
around without corresponding user space mapping.
This is similar to dangling pinned regions and should likely be
addressed the same way by utilizing MMU notifiers to destpoy memoty
regions is VMA is detached.
Accessing the list of regions without lock is unsafe.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Mon, 26 Jan 2026 10:15:53 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Fri, Jan 23, 2026 at 04:42:54PM -0800, Mukesh R wrote:
Why not placing the caller side after the function definition then?
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Mon, 26 Jan 2026 12:50:03 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/26/26 07:57, Stanislav Kinsburskii wrote:
Error is printed in case of failed detach. If there is panic, at least
you can get some info about the device. Metadata in hypervisor is
around if failed.
Unmap does not need intermediate function.
We print error upon its failure in hv_iommu_map_pages():
if (!hv_result_success(status)) {
size_t done_size = done << HV_HYP_PAGE_SHIFT;
hv_status_err(status, "pgs:%lx/%lx iova:%lx\n",
done, npages, iova);
I hear you... but,
o there is nothing under sysfs to be accessed when created
o it is during boot
o it should almost never fail...
o iommu_device_sysfs_remove is much more light weight than
iommu_device_unregister
o i expect more to be added there as we enhance it
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 26 Jan 2026 19:02:29 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/26/26 10:15, Stanislav Kinsburskii wrote:
Right, and vm_flags would not be mmio expected then.
I don't think we need that. Either it succeeds if the region did not
change at all, or just fails.
I am not sure why? This check is done by a vcpu thread, so regions
will not have just gone away.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Mon, 26 Jan 2026 19:07:22 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 26, 2026 at 07:02:29PM -0800, Mukesh R wrote:
With this approach the only thing left is a kernel message.
But if the state is kept intact, one could collect a kernel core and
analyze it.
And note, that there won't be a hypervisor core by default: our main
context with the usptreamed version of the driver is L1VH and a kernel
core is the only thing a third party customer can provide for our
analysis.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 27 Jan 2026 10:46:49 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 26, 2026 at 07:07:22PM -0800, Mukesh R wrote:
I'm afraid we do, as if the driver mapped a page with the previous
memory region, and then the region is unmapped, the page will stay
mapped in the hypervisor, but will be considered free by kernel, which
in turn will lead to GPF upn next allocation.
With pinned regions we issue is similar but less impacting: pages can't
be released by user space unmapping and thus will be simply leaked, but
the system stays intact.
MMIO regions are simila to movable region in this regard: they don't
reference the user pages, and thus this guest region replaement is a
stright wat to kernel panic.
This is shared resources. Multiple VP thread get into this function
simultaneously, so there is a race already. But this one we can live
with without locking as they don't mutate the list of the regions.
The issue happens when VMM adds or removed another region as it mutates
the list and races with VP threads doing this lookup.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Tue, 27 Jan 2026 10:57:08 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
Hi Mukesh,
On Fri, 23 Jan 2026 18:01:29 -0800
Mukesh R <mrathor@linux.microsoft.com> wrote:
yeah, something specific and different than the guest driver will do.
If there is nothing x86 specific in this driver (assuming the
hypercalls here are not x86 only), maybe you can move to the generic
startup code.
In IOMMU subsystem, DMA remapping and IRQ remapping can be turned
on/off independently. e.g. you could have an option to turn on IRQ
remapping w/o DMA remapping. But here you tied them together.
ok, maybe move it to mshv after we have a second user. But the function
name can be just hv_get_curr_partid(void), no?
I was thinking the device can be attached to a different domain type at
runtime, e.g. via sysfs to identity or DMA. But I guess here is a static
attachment either for l1vh or root.
This hv_no_attdev flag is really confusing to me, by default
hv_no_attdev is false, which allows direct attach. And you are saying
l1vh allows it.
Why is this flag also controls host device attachment in l1vh? If you
can tell the difference between direct host device attach and other
direct attach, why don't you reject always reject host attach in l1vh?
This is still a unnecessary vulnerability.
yes.
where is this repo?
you are right, this is a very recent change. my bad.
|
{
"author": "Jacob Pan <jacob.pan@linux.microsoft.com>",
"date": "Tue, 27 Jan 2026 11:21:44 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
Hi Mukesh,
On second thought, if the hv_no_attdev knob is only meant to control
host domain attach vs. direct attach, then it is irrelevant on L1VH.
Would it make more sense to rename this to something like
hv_host_disable_direct_attach? That would better reflect its scope and
allow it to be ignored under L1VH, and reduce the risk of users
misinterpreting or misusing it.
|
{
"author": "Jacob Pan <jacob.pan@linux.microsoft.com>",
"date": "Tue, 27 Jan 2026 14:31:19 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Mon, Jan 19, 2026 at 10:42:23PM -0800, Mukesh R wrote:
Don't mix up cleanup changes. Do it in a separate patch.
- Mani
--
மணிவண்ணன் சதாசிவம்
|
{
"author": "Manivannan Sadhasivam <mani@kernel.org>",
"date": "Wed, 28 Jan 2026 19:33:57 +0530",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Fri, Jan 23, 2026 at 04:42:54PM -0800, Mukesh R wrote:
Such debug print do not exist now. So there is no need of a variable, drop it.
- Mani
--
மணிவண்ணன் சதாசிவம்
|
{
"author": "Manivannan Sadhasivam <mani@kernel.org>",
"date": "Wed, 28 Jan 2026 20:06:21 +0530",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/27/26 14:31, Jacob Pan wrote:
It would, but it is kernel parameter and needs to be terse. It would
be documented properly tho, so we should be ok.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 30 Jan 2026 14:10:57 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/27/26 10:57, Stanislav Kinsburskii wrote:
There are no ram pages for mmio regions. Also, we don't do much with
mmio regions other than tell the hyp about it.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 30 Jan 2026 14:17:24 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/27/26 10:46, Stanislav Kinsburskii wrote:
Again, most of linux stuff is cleaned up, the only state is in
hypervisor, and hypervisor can totally protect itself and devices.
So there is not much in kernel core as it got cleaned up already.
Think of this as additional check, we can remove in future after
it stands the test of time, until then, every debugging bit helps.
Wei can correct me, but we are not only l1vh focused here. There is
work going on on all fronts.
Thanks,
-Mukesh
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 30 Jan 2026 14:51:19 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On 1/27/26 11:21, Jacob Pan wrote:
It's x86 specific:
x86_init.iommu.iommu_init = hv_iommu_init
oh, you are talking about the config option, yeah, I will move
CONFIG_IRQ_REMAP from Kconfig to here.
it could, but by convention all public funcs here are hv_iommu_xxx..
and other reviewers might object... We really need virt/mshv/
sub directory... not sure if it's worth creating now for just one
function. so maybe we just live with it for now... we do have work
item to move some things from drivers/hv to virt/mshv/ .. so this
can get added to that whenever that happens.
That is correct. It is extra work to support that if there is a good
usecase/demand.
Well, at the time of this design/coding, my understanding was we'd have
mapped devices on l1vh also. But now it looks like that would be bit
later than sooner .. unless AI bots start dumping code of course :) :)..
I could remove it from the if statement and add it when the support
is added, but is harmless and one less thing to remember.
Device passthru will fail and will not cause any corruption or
data theft issues... can make it u64 if it gives extra peace. not
worth all that mumbo jumbo for almost never gonna happen case.
no it's just a sequential number with no track of what's used.
https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git
branch: hyperv-next
All our hyperv/mshv related patch submissions are merged there
first by Wei.
Thanks,
-Mukesh
.. deleted ......
|
{
"author": "Mukesh R <mrathor@linux.microsoft.com>",
"date": "Fri, 30 Jan 2026 15:44:37 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
lkml
|
[PATCH v0 00/15] PCI passthru on Hyper-V (Part I)
|
From: Mukesh Rathor <mrathor@linux.microsoft.com>
Implement passthru of PCI devices to unprivileged virtual machines
(VMs) when Linux is running as a privileged VM on Microsoft Hyper-V
hypervisor. This support is made to fit within the workings of VFIO
framework, and any VMM needing to use it must use the VFIO subsystem.
This supports both full device passthru and SR-IOV based VFs.
There are 3 cases where Linux can run as a privileged VM (aka MSHV):
Baremetal root (meaning Hyper-V+Linux), L1VH, and Nested.
At a high level, the hypervisor supports traditional mapped iommu domains
that use explicit map and unmap hypercalls for mapping and unmapping guest
RAM into the iommu subsystem. Hyper-V also has a concept of direct attach
devices whereby the iommu subsystem simply uses the guest HW page table
(ept/npt/..). This series adds support for both, and both are made to
work in VFIO type1 subsystem.
While this Part I focuses on memory mappings, upcoming Part II
will focus on irq bypass along with some minor irq remapping
updates.
This patch series was tested using Cloud Hypervisor verion 48. Qemu
support of MSHV is in the works, and that will be extended to include
PCI passthru and SR-IOV support also in near future.
Based on: 8f0b4cce4481 (origin/hyperv-next)
Thanks,
-Mukesh
Mukesh Rathor (15):
iommu/hyperv: rename hyperv-iommu.c to hyperv-irq.c
x86/hyperv: cosmetic changes in irqdomain.c for readability
x86/hyperv: add insufficient memory support in irqdomain.c
mshv: Provide a way to get partition id if running in a VMM process
mshv: Declarations and definitions for VFIO-MSHV bridge device
mshv: Implement mshv bridge device for VFIO
mshv: Add ioctl support for MSHV-VFIO bridge device
PCI: hv: rename hv_compose_msi_msg to hv_vmbus_compose_msi_msg
mshv: Import data structs around device domains and irq remapping
PCI: hv: Build device id for a VMBus device
x86/hyperv: Build logical device ids for PCI passthru hcalls
x86/hyperv: Implement hyperv virtual iommu
x86/hyperv: Basic interrupt support for direct attached devices
mshv: Remove mapping of mmio space during map user ioctl
mshv: Populate mmio mappings for PCI passthru
MAINTAINERS | 1 +
arch/arm64/include/asm/mshyperv.h | 15 +
arch/x86/hyperv/irqdomain.c | 314 ++++++---
arch/x86/include/asm/mshyperv.h | 21 +
arch/x86/kernel/pci-dma.c | 2 +
drivers/hv/Makefile | 3 +-
drivers/hv/mshv_root.h | 24 +
drivers/hv/mshv_root_main.c | 296 +++++++-
drivers/hv/mshv_vfio.c | 210 ++++++
drivers/iommu/Kconfig | 1 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/hyperv-iommu.c | 1004 +++++++++++++++++++++------
drivers/iommu/hyperv-irq.c | 330 +++++++++
drivers/pci/controller/pci-hyperv.c | 207 ++++--
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 11 +
include/hyperv/hvhdk_mini.h | 112 +++
include/linux/hyperv.h | 6 +
include/uapi/linux/mshv.h | 31 +
19 files changed, 2182 insertions(+), 409 deletions(-)
create mode 100644 drivers/hv/mshv_vfio.c
create mode 100644 drivers/iommu/hyperv-irq.c
--
2.51.2.vfs.0.1
|
On Fri, Jan 30, 2026 at 02:51:19PM -0800, Mukesh R wrote:
Again, the hypervisor state is not accessible from the kernel core in
L1VH.
In upstream, it does not matter what the work is focused on. The only
thing that matters is that the functionality is merged and available.
Once the code is merged upstream, it becomes available to third-party
customers. They can use it in any way they see fit.
The only product we support with upstream code is L1VH. We should keep
it crisp, clear, and easy to debug.
This change does not help debugging. It only sweeps the issue under the
carpet, with no justification.
Thanks,
Stanislav
|
{
"author": "Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>",
"date": "Mon, 2 Feb 2026 08:20:37 -0800",
"thread_id": "aYDO1S3DdUSHNkEY@skinsburskii.localdomain.mbox.gz"
}
|
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