The BTF dumper code currently displays arrays of characters as just that -
arrays, with each character formatted individually. Sometimes this is what
makes sense, but it's nice to be able to treat that array as a string.
This change adds a special case to the btf_dump functionality to allow
0-terminated arrays of single-byte integer values to be printed as
character strings. Characters for which isprint() returns false are
printed as hex-escaped values. This is enabled when the new ".emit_strings"
is set to 1 in the btf_dump_type_data_opts structure.
As an example, here's what it looks like to dump the string "hello" using
a few different field values for btf_dump_type_data_opts (.compact = 1):
- .emit_strings = 0, .skip_names = 0: (char[6])['h','e','l','l','o',]
- .emit_strings = 0, .skip_names = 1: ['h','e','l','l','o',]
- .emit_strings = 1, .skip_names = 0: (char[6])"hello"
- .emit_strings = 1, .skip_names = 1: "hello"
Here's the string "h\xff", dumped with .compact = 1 and .skip_names = 1:
- .emit_strings = 0: ['h',-1,]
- .emit_strings = 1: "h\xff"
Signed-off-by: Blake Jones <blakejones(a)google.com>
---
tools/lib/bpf/btf.h | 3 ++-
tools/lib/bpf/btf_dump.c | 55 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 56 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 4392451d634b..ccfd905f03df 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -326,9 +326,10 @@ struct btf_dump_type_data_opts {
bool compact; /* no newlines/indentation */
bool skip_names; /* skip member/type names */
bool emit_zeroes; /* show 0-valued fields */
+ bool emit_strings; /* print char arrays as strings */
size_t :0;
};
-#define btf_dump_type_data_opts__last_field emit_zeroes
+#define btf_dump_type_data_opts__last_field emit_strings
LIBBPF_API int
btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 460c3e57fadb..7c2f1f13f958 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -68,6 +68,7 @@ struct btf_dump_data {
bool compact;
bool skip_names;
bool emit_zeroes;
+ bool emit_strings;
__u8 indent_lvl; /* base indent level */
char indent_str[BTF_DATA_INDENT_STR_LEN];
/* below are used during iteration */
@@ -2028,6 +2029,52 @@ static int btf_dump_var_data(struct btf_dump *d,
return btf_dump_dump_type_data(d, NULL, t, type_id, data, 0, 0);
}
+static int btf_dump_string_data(struct btf_dump *d,
+ const struct btf_type *t,
+ __u32 id,
+ const void *data)
+{
+ const struct btf_array *array = btf_array(t);
+ const char *chars = data;
+ __u32 i;
+
+ /* Make sure it is a NUL-terminated string. */
+ for (i = 0; i < array->nelems; i++) {
+ if ((void *)(chars + i) >= d->typed_dump->data_end)
+ return -E2BIG;
+ if (chars[i] == '\0')
+ break;
+ }
+ if (i == array->nelems) {
+ /* The caller will print this as a regular array. */
+ return -EINVAL;
+ }
+
+ btf_dump_data_pfx(d);
+ btf_dump_printf(d, "\"");
+
+ for (i = 0; i < array->nelems; i++) {
+ char c = chars[i];
+
+ if (c == '\0') {
+ /*
+ * When printing character arrays as strings, NUL bytes
+ * are always treated as string terminators; they are
+ * never printed.
+ */
+ break;
+ }
+ if (isprint(c))
+ btf_dump_printf(d, "%c", c);
+ else
+ btf_dump_printf(d, "\\x%02x", (__u8)c);
+ }
+
+ btf_dump_printf(d, "\"");
+
+ return 0;
+}
+
static int btf_dump_array_data(struct btf_dump *d,
const struct btf_type *t,
__u32 id,
@@ -2055,8 +2102,13 @@ static int btf_dump_array_data(struct btf_dump *d,
* char arrays, so if size is 1 and element is
* printable as a char, we'll do that.
*/
- if (elem_size == 1)
+ if (elem_size == 1) {
+ if (d->typed_dump->emit_strings &&
+ btf_dump_string_data(d, t, id, data) == 0) {
+ return 0;
+ }
d->typed_dump->is_array_char = true;
+ }
}
/* note that we increment depth before calling btf_dump_print() below;
@@ -2544,6 +2596,7 @@ int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
d->typed_dump->compact = OPTS_GET(opts, compact, false);
d->typed_dump->skip_names = OPTS_GET(opts, skip_names, false);
d->typed_dump->emit_zeroes = OPTS_GET(opts, emit_zeroes, false);
+ d->typed_dump->emit_strings = OPTS_GET(opts, emit_strings, false);
ret = btf_dump_dump_type_data(d, NULL, t, id, data, 0, 0);
--
2.49.0.1204.g71687c7c1d-goog
This series creates a new PMU scheme on ARM, a partitioned PMU that
allows reserving a subset of counters for more direct guest access,
significantly reducing overhead. More details, including performance
benchmarks, can be read in the v1 cover letter linked below.
v4:
* Apply Mark Brown's non-UNDEF FGT control commit to the PMU FGT
controls and calculate those controls with the others in
kvm_calculate_traps()
* Introduce lazy context swaps for guests that only turns on for
guests that have enabled partitioning and accessed PMU registers.
* Rename pmu-part.c to pmu-direct.c because future features might
achieve direct PMU access without partitioning.
* Better explain certain commits, such as why the untrapped registers
are safe to untrap.
* Reduce the PMU include cleanup down to only what is still necessary
and explain why.
v3:
https://lore.kernel.org/kvm/20250626200459.1153955-1-coltonlewis@google.com/
v2:
https://lore.kernel.org/kvm/20250620221326.1261128-1-coltonlewis@google.com/
v1:
https://lore.kernel.org/kvm/20250602192702.2125115-1-coltonlewis@google.com/
Colton Lewis (21):
arm64: cpufeature: Add cpucap for HPMN0
KVM: arm64: Reorganize PMU functions
perf: arm_pmuv3: Introduce method to partition the PMU
perf: arm_pmuv3: Generalize counter bitmasks
perf: arm_pmuv3: Keep out of guest counter partition
KVM: arm64: Account for partitioning in kvm_pmu_get_max_counters()
KVM: arm64: Set up FGT for Partitioned PMU
KVM: arm64: Writethrough trapped PMEVTYPER register
KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned
KVM: arm64: Writethrough trapped PMOVS register
KVM: arm64: Write fast path PMU register handlers
KVM: arm64: Setup MDCR_EL2 to handle a partitioned PMU
KVM: arm64: Account for partitioning in PMCR_EL0 access
KVM: arm64: Context swap Partitioned PMU guest registers
KVM: arm64: Enforce PMU event filter at vcpu_load()
KVM: arm64: Extract enum debug_owner to enum vcpu_register_owner
KVM: arm64: Implement lazy PMU context swaps
perf: arm_pmuv3: Handle IRQs for Partitioned PMU guest counters
KVM: arm64: Inject recorded guest interrupts
KVM: arm64: Add ioctl to partition the PMU when supported
KVM: arm64: selftests: Add test case for partitioned PMU
Marc Zyngier (1):
KVM: arm64: Reorganize PMU includes
Mark Brown (1):
KVM: arm64: Introduce non-UNDEF FGT control
Documentation/virt/kvm/api.rst | 21 +
arch/arm/include/asm/arm_pmuv3.h | 38 +
arch/arm64/include/asm/arm_pmuv3.h | 61 +-
arch/arm64/include/asm/kvm_host.h | 34 +-
arch/arm64/include/asm/kvm_pmu.h | 123 +++
arch/arm64/include/asm/kvm_types.h | 7 +-
arch/arm64/kernel/cpufeature.c | 8 +
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arm.c | 22 +
arch/arm64/kvm/debug.c | 33 +-
arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 6 +-
arch/arm64/kvm/hyp/include/hyp/switch.h | 181 ++++-
arch/arm64/kvm/pmu-direct.c | 395 ++++++++++
arch/arm64/kvm/pmu-emul.c | 674 +---------------
arch/arm64/kvm/pmu.c | 725 ++++++++++++++++++
arch/arm64/kvm/sys_regs.c | 137 +++-
arch/arm64/tools/cpucaps | 1 +
arch/arm64/tools/sysreg | 6 +-
drivers/perf/arm_pmuv3.c | 128 +++-
include/linux/perf/arm_pmu.h | 1 +
include/linux/perf/arm_pmuv3.h | 14 +-
include/uapi/linux/kvm.h | 4 +
tools/include/uapi/linux/kvm.h | 2 +
.../selftests/kvm/arm64/vpmu_counter_access.c | 62 +-
24 files changed, 1910 insertions(+), 775 deletions(-)
create mode 100644 arch/arm64/kvm/pmu-direct.c
base-commit: 79150772457f4d45e38b842d786240c36bb1f97f
--
2.50.0.727.gbf7dc18ff4-goog
The check of is_backed_by_folio() is done on each page.
Directly move pointer to next page instead of increase one and check if
it is page size aligned.
Signed-off-by: Wei Yang <richard.weiyang(a)gmail.com>
---
tools/testing/selftests/mm/split_huge_page_test.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 10ae65ea032f..7f7016ba4054 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -423,9 +423,8 @@ static void split_pte_mapped_thp(void)
/* smap does not show THPs after mremap, use kpageflags instead */
thp_size = 0;
- for (i = 0; i < pagesize * 4; i++)
- if (i % pagesize == 0 &&
- is_backed_by_folio(&pte_mapped[i], pmd_order, pagemap_fd, kpageflags_fd))
+ for (i = 0; i < pagesize * 4; i += pagesize)
+ if (is_backed_by_folio(&pte_mapped[i], pmd_order, pagemap_fd, kpageflags_fd))
thp_size++;
if (thp_size != 4)
--
2.34.1
[All the precursor patches are merged now and AMD/RISCV/VTD conversions
are written]
Currently each of the iommu page table formats duplicates all of the logic
to maintain the page table and perform map/unmap/etc operations. There are
several different versions of the algorithms between all the different
formats. The io-pgtable system provides an interface to help isolate the
page table code from the iommu driver, but doesn't provide tools to
implement the common algorithms.
This makes it very hard to improve the state of the pagetable code under
the iommu domains as any proposed improvement needs to alter a large
number of different driver code paths. Combined with a lack of software
based testing this makes improvement in this area very hard.
iommufd wants several new page table operations:
- More efficient map/unmap operations, using iommufd's batching logic
- unmap that returns the physical addresses into a batch as it progresses
- cut that allows splitting areas so large pages can have holes
poked in them dynamically (ie guestmemfd hitless shared/private
transitions)
- More agressive freeing of table memory to avoid waste
- Fragmenting large pages so that dirty tracking can be more granular
- Reassembling large pages so that VMs can run at full IO performance
in migration/dirty tracking error flows
- KHO integration for kernel live upgrade
Together these are algorithmically complex enough to be a very significant
task to go and implement in all the page table formats we support. Just
the "server" focused drivers use almost all the formats (ARMv8 S1&S2 / x86
PAE / AMDv1 / VT-D SS / RISCV)
Instead of doing the duplicated work, this series takes the first step to
consolidate the algorithms into one places. In spirit it is similar to the
work Christoph did a few years back to pull the redundant get_user_pages()
implementations out of the arch code into core MM. This unlocked a great
deal of improvement in that space in the following years. I would like to
see the same benefit in iommu as well.
My first RFC showed a bigger picture with all most all formats and more
algorithms. This series reorganizes that to be narrowly focused on just
enough to convert the AMD driver to use the new mechanism.
kunit tests are provided that allow good testing of the algorithms and all
formats on x86, nothing is arch specific.
AMD is one of the simpler options as the HW is quite uniform with few
different options/bugs while still requiring the complicated contiguous
pages support. The HW also has a very simple range based invalidation
approach that is easy to implement.
The AMD v1 and AMD v2 page table formats are implemented bit for bit
identical to the current code, tested using a compare kunit test that
checks against the io-pgtable version (on github, see below).
Updating the AMD driver to replace the io-pgtable layer with the new stuff
is fairly straightforward now. The layering is fixed up in the new version
so that all the invalidation goes through function pointers.
Several small fixing patches have come out of this as I've been fixing the
problems that the test suite uncovers in the current code, and
implementing the fixed version in iommupt.
On performance, there is a quite wide variety of implementation designs
across all the drivers. Looking at some key performance across
the main formats:
iommu_map():
pgsz ,avg new,old ns, min new,old ns , min % (+ve is better)
2^12, 53,66 , 51,63 , 19.19 (AMDV1)
256*2^12, 386,1909 , 367,1795 , 79.79
256*2^21, 362,1633 , 355,1556 , 77.77
2^12, 56,62 , 52,59 , 11.11 (AMDv2)
256*2^12, 405,1355 , 357,1292 , 72.72
256*2^21, 393,1160 , 358,1114 , 67.67
2^12, 55,65 , 53,62 , 14.14 (VTD second stage)
256*2^12, 391,518 , 332,512 , 35.35
256*2^21, 383,635 , 336,624 , 46.46
2^12, 57,65 , 55,63 , 12.12 (ARM 64 bit)
256*2^12, 380,389 , 361,369 , 2.02
256*2^21, 358,419 , 345,400 , 13.13
iommu_unmap():
pgsz ,avg new,old ns, min new,old ns , min % (+ve is better)
2^12, 69,88 , 65,85 , 23.23 (AMDv1)
256*2^12, 353,6498 , 331,6029 , 94.94
256*2^21, 373,6014 , 360,5706 , 93.93
2^12, 71,72 , 66,69 , 4.04 (AMDv2)
256*2^12, 228,891 , 206,871 , 76.76
256*2^21, 254,721 , 245,711 , 65.65
2^12, 69,87 , 65,82 , 20.20 (VTD second stage)
256*2^12, 210,321 , 200,315 , 36.36
256*2^21, 255,349 , 238,342 , 30.30
2^12, 72,77 , 68,74 , 8.08 (ARM 64 bit)
256*2^12, 521,357 , 447,346 , -29.29
256*2^21, 489,358 , 433,345 , -25.25
* Above numbers include additional patches to remove the iommu_pgsize()
overheads. gcc 13.3.0, i7-12700
This version provides fairly consistent performance across formats. ARM
unmap performance is quite different because this version supports
contiguous pages and uses a very different algorithm for unmapping. Though
why it is so worse compared to AMDv1 I haven't figured out yet.
The per-format commits include a more detailed chart.
There is a second branch:
https://github.com/jgunthorpe/linux/commits/iommu_pt_all
Containing supporting work and future steps:
- ARM short descriptor (32 bit), ARM long descriptor (64 bit) formats
- RISCV format and RISCV conversion
https://github.com/jgunthorpe/linux/commits/iommu_pt_riscv
- Support for a DMA incoherent HW page table walker
- VT-D second stage format and VT-D conversion
https://github.com/jgunthorpe/linux/commits/iommu_pt_vtd
- DART v1 & v2 format
- Draft of a iommufd 'cut' operation to break down huge pages
- A compare test that checks the iommupt formats against the iopgtable
interface, including updating AMD to have a working iopgtable and patches
to make VT-D have an iopgtable for testing.
- A performance test to micro-benchmark map and unmap against iogptable
My strategy is to go one by one for the drivers:
- AMD driver conversion
- RISCV page table and driver
- Intel VT-D driver and VTDSS page table
- Flushing improvements for RISCV
- ARM SMMUv3
And concurrently work on the algorithm side:
- debugfs content dump, like VT-D has
- Cut support
- Increase/Decrease page size support
- map/unmap batching
- KHO
As we make more algorithm improvements the value to convert the drivers
increases.
This is on github: https://github.com/jgunthorpe/linux/commits/iommu_pt
v3:
- Rebase on v6.16-rc3
- Integrate the HATS/HATDis changes
- Remove 'default n' from kconfig
- Remove unused 'PT_FIXED_TOP_LEVEL'
- Improve comments and coumentation
- Fix some compile warnings from kbuild robots
v2: https://patch.msgid.link/r/0-v3-a93aab628dbc+521-iommu_pt_jgg@nvidia.com
- Rebase on v6.16-rc2
- s/PT_ENTRY_WORD_SIZE/PT_ITEM_WORD_SIZE/s to follow the language better
- Comment and documentation updates
- Add PT_TOP_PHYS_MASK to help manage alignment restrictions on the top
pointer
- Add missed force_aperture = true
- Make pt_iommu_deinit() take care of the not-yet-inited error case
internally as AMD/RISCV/VTD all shared this logic
- Change gather_range() into gather_range_pages() so it also deals with
the page list. This makes the following cache flushing series simpler
- Fix missed update of unmap->unmapped in some error cases
- Change clear_contig() to order the gather more logically
- Remove goto from the error handling in __map_range_leaf()
- s/log2_/oalog2_/ in places where the argument is an oaddr_t
- Pass the pts to pt_table_install64/32()
- Do not use SIGN_EXTEND for the AMDv2 page table because of Vasant's
information on how PASID 0 works.
v1: https://patch.msgid.link/r/0-v2-5c26bde5c22d+58b-iommu_pt_jgg@nvidia.com
- AMD driver only, many code changes
RFC: https://lore.kernel.org/all/0-v1-01fa10580981+1d-iommu_pt_jgg@nvidia.com/
Cc: Michael Roth <michael.roth(a)amd.com>
Cc: Alexey Kardashevskiy <aik(a)amd.com>
Cc: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Cc: James Gowans <jgowans(a)amazon.com>
Signed-off-by: Jason Gunthorpe <jgg(a)nvidia.com>
Alejandro Jimenez (1):
iommu/amd: Use the generic iommu page table
Jason Gunthorpe (14):
genpt: Generic Page Table base API
genpt: Add Documentation/ files
iommupt: Add the basic structure of the iommu implementation
iommupt: Add the AMD IOMMU v1 page table format
iommupt: Add iova_to_phys op
iommupt: Add unmap_pages op
iommupt: Add map_pages op
iommupt: Add read_and_clear_dirty op
iommupt: Add a kunit test for Generic Page Table
iommupt: Add a mock pagetable format for iommufd selftest to use
iommufd: Change the selftest to use iommupt instead of xarray
iommupt: Add the x86 64 bit page table format
iommu/amd: Remove AMD io_pgtable support
iommupt: Add a kunit test for the IOMMU implementation
.clang-format | 1 +
Documentation/driver-api/generic_pt.rst | 140 ++
Documentation/driver-api/index.rst | 1 +
drivers/iommu/Kconfig | 2 +
drivers/iommu/Makefile | 1 +
drivers/iommu/amd/Kconfig | 5 +-
drivers/iommu/amd/Makefile | 2 +-
drivers/iommu/amd/amd_iommu.h | 1 -
drivers/iommu/amd/amd_iommu_types.h | 109 +-
drivers/iommu/amd/io_pgtable.c | 560 --------
drivers/iommu/amd/io_pgtable_v2.c | 370 ------
drivers/iommu/amd/iommu.c | 538 ++++----
drivers/iommu/generic_pt/.kunitconfig | 13 +
drivers/iommu/generic_pt/Kconfig | 67 +
drivers/iommu/generic_pt/fmt/Makefile | 26 +
drivers/iommu/generic_pt/fmt/amdv1.h | 409 ++++++
drivers/iommu/generic_pt/fmt/defs_amdv1.h | 21 +
drivers/iommu/generic_pt/fmt/defs_x86_64.h | 21 +
drivers/iommu/generic_pt/fmt/iommu_amdv1.c | 15 +
drivers/iommu/generic_pt/fmt/iommu_mock.c | 10 +
drivers/iommu/generic_pt/fmt/iommu_template.h | 48 +
drivers/iommu/generic_pt/fmt/iommu_x86_64.c | 11 +
drivers/iommu/generic_pt/fmt/x86_64.h | 248 ++++
drivers/iommu/generic_pt/iommu_pt.h | 1146 +++++++++++++++++
drivers/iommu/generic_pt/kunit_generic_pt.h | 717 +++++++++++
drivers/iommu/generic_pt/kunit_iommu.h | 183 +++
drivers/iommu/generic_pt/kunit_iommu_pt.h | 451 +++++++
drivers/iommu/generic_pt/pt_common.h | 354 +++++
drivers/iommu/generic_pt/pt_defs.h | 323 +++++
drivers/iommu/generic_pt/pt_fmt_defaults.h | 193 +++
drivers/iommu/generic_pt/pt_iter.h | 636 +++++++++
drivers/iommu/generic_pt/pt_log2.h | 130 ++
drivers/iommu/io-pgtable.c | 4 -
drivers/iommu/iommufd/Kconfig | 1 +
drivers/iommu/iommufd/iommufd_test.h | 11 +-
drivers/iommu/iommufd/selftest.c | 438 +++----
include/linux/generic_pt/common.h | 166 +++
include/linux/generic_pt/iommu.h | 270 ++++
include/linux/io-pgtable.h | 2 -
tools/testing/selftests/iommu/iommufd.c | 60 +-
tools/testing/selftests/iommu/iommufd_utils.h | 12 +
41 files changed, 6124 insertions(+), 1592 deletions(-)
create mode 100644 Documentation/driver-api/generic_pt.rst
delete mode 100644 drivers/iommu/amd/io_pgtable.c
delete mode 100644 drivers/iommu/amd/io_pgtable_v2.c
create mode 100644 drivers/iommu/generic_pt/.kunitconfig
create mode 100644 drivers/iommu/generic_pt/Kconfig
create mode 100644 drivers/iommu/generic_pt/fmt/Makefile
create mode 100644 drivers/iommu/generic_pt/fmt/amdv1.h
create mode 100644 drivers/iommu/generic_pt/fmt/defs_amdv1.h
create mode 100644 drivers/iommu/generic_pt/fmt/defs_x86_64.h
create mode 100644 drivers/iommu/generic_pt/fmt/iommu_amdv1.c
create mode 100644 drivers/iommu/generic_pt/fmt/iommu_mock.c
create mode 100644 drivers/iommu/generic_pt/fmt/iommu_template.h
create mode 100644 drivers/iommu/generic_pt/fmt/iommu_x86_64.c
create mode 100644 drivers/iommu/generic_pt/fmt/x86_64.h
create mode 100644 drivers/iommu/generic_pt/iommu_pt.h
create mode 100644 drivers/iommu/generic_pt/kunit_generic_pt.h
create mode 100644 drivers/iommu/generic_pt/kunit_iommu.h
create mode 100644 drivers/iommu/generic_pt/kunit_iommu_pt.h
create mode 100644 drivers/iommu/generic_pt/pt_common.h
create mode 100644 drivers/iommu/generic_pt/pt_defs.h
create mode 100644 drivers/iommu/generic_pt/pt_fmt_defaults.h
create mode 100644 drivers/iommu/generic_pt/pt_iter.h
create mode 100644 drivers/iommu/generic_pt/pt_log2.h
create mode 100644 include/linux/generic_pt/common.h
create mode 100644 include/linux/generic_pt/iommu.h
base-commit: 8da0d63bd5726ff656bfa1eacb45d6f5cce65616
--
2.43.0
The pthread_attr_setaffinity_np function is a GNU extension that may not
be available in non-glibc C libraries. Some KVM selftests use this
function for CPU affinity control.
Add a function declaration and weak stub implementation for non-glibc
builds. This allows tests to build, with the affinity setting being a
no-op and errno set for the caller when the actual function is not available.
Signed-off-by: Aqib Faruqui <aqibaf(a)amazon.com>
---
tools/testing/selftests/kvm/include/kvm_util.h | 4 ++++
tools/testing/selftests/kvm/lib/kvm_util.c | 11 +++++++++++
2 files changed, 15 insertions(+)
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 7fae7f5e7..8177178b5 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -31,6 +31,10 @@
#include "kvm_util_types.h"
#include "sparsebit.h"
+#ifndef __GLIBC__
+int pthread_attr_setaffinity_np(pthread_attr_t *attr, size_t cpusetsize, const cpu_set_t *cpuset);
+#endif /* __GLIBC__ */
+
#define KVM_DEV_PATH "/dev/kvm"
#define KVM_MAX_VCPUS 512
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index c3f5142b0..5ce80303d 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -20,6 +20,17 @@
#define KVM_UTIL_MIN_PFN 2
+#ifndef __GLIBC__
+int __attribute__((weak))
+pthread_attr_setaffinity_np(pthread_attr_t *__attr,
+ size_t __cpusetsize,
+ const cpu_set_t *__cpuset)
+{
+ errno = ENOSYS;
+ return -1;
+}
+#endif
+
uint32_t guest_random_seed;
struct guest_random_state guest_rng;
static uint32_t last_guest_seed;
--
2.47.3