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Currently, each of the three xstate tests runs as a separate invocation,
requiring the xstate number to be passed and state information to be
reconstructed repeatedly. This approach arose from their individual and
isolated development, but now it makes sense to unify them.
Introduce a wrapper function that first verifies feature availability
from the kernel and constructs the necessary state information once. The
wrapper then sequentially invokes all tests to ensure consistent
execution.
Update the AMX test to use this unified invocation.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226010731.2456-8-chang.seok.bae@intel.com
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With the refactored test cases, another xstate exposure to userspace is
through signal delivery. While amx.c includes signal-related scenarios,
its primary focus is on xstate permission management, which is largely
specific to dynamic states.
The remaining gap is testing xstate preservation and restoration across
signal delivery. The kernel defines an ABI for presenting xstate in the
signal frame, closely resembling the hardware XSAVE format, where xstate
modification is also possible.
Introduce a new test case to verify xstate preservation across signal
delivery and return, that is ensuring ABI compatibility by:
- Loading xstate before raising a signal.
- Verifying correct exposure in the signal frame
- Modifying xstate in the signal frame before returning.
- Checking the state restoration upon signal return.
Integrate this test into the AMX test suite as an initial usage site.
Expected output:
$ amx_64
...
[RUN] AMX Tile data: load xstate and raise SIGUSR1
[OK] 'magic1' is valid
[OK] 'xfeatures' in SW reserved area is valid
[OK] 'xfeatures' in XSAVE header is valid
[OK] xstate delivery was successful
[OK] 'magic2' is valid
[RUN] AMX Tile data: load new xstate from sighandler and check it after sigreturn
[OK] xstate was restored correctly
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226010731.2456-7-chang.seok.bae@intel.com
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Following the refactoring of the context switching test, the ptrace test is
another component reusable for other xstate features. As part of this
restructuring, add a missing check to validate the
user_xstateregs->xstate_fx_sw field in the ABI.
Also, replace err() and fatal_error() with ksft_exit_fail_msg() for
consistency in error handling.
Expected output:
$ amx_64
...
[RUN] AMX Tile data: inject xstate via ptrace().
[OK] 'xfeatures' in SW reserved area was correctly written
[OK] xstate was correctly updated.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226010731.2456-6-chang.seok.bae@intel.com
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The existing context switching and ptrace tests in amx.c are not specific
to dynamic states, making them reusable for general xstate testing.
As a first step, move the context switching test to xstate.c. Refactor
the test code to allow specifying which xstate component being tested.
To decouple the test from dynamic states, remove the permission request
code. In fact, The permission request inside the test wrapper was
redundant.
Additionally, replace fatal_error() with ksft_exit_fail_msg() for
consistency in error handling.
Expected output:
$ amx_64
...
[RUN] AMX Tile data: check context switches, 10 iterations, 5 threads.
[OK] No incorrect case was found.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226010731.2456-5-chang.seok.bae@intel.com
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After moving essential helpers from amx.c, the code remains neutral
regarding which xstate components it handles. However, explicitly listing
known components helps users identify which features are ready for
testing.
Enumerate xstate components to facilitate identification. Extend struct
xstate_info to include a name field, providing a human-readable
identifier.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226010731.2456-4-chang.seok.bae@intel.com
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The AMX test introduced several XSAVE-related helper functions, but so
far, it has been the only user of them. These helpers can be generalized
for broader test of multiple xstate features.
Move most XSAVE-related code into xsave.h, making it shareable. The
restructuring includes:
* Establishing low-level XSAVE helpers for saving and restoring register
states, as well as handling XSAVE buffers.
* Generalizing state data manipuldations: set_rand_data()
* Introducing a generic feature query helper: get_xstate_info()
While doing so, remove unused defines in amx.c.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226010731.2456-3-chang.seok.bae@intel.com
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The x86 selftests frequently register and clean up signal handlers, but
the sethandler() and clearhandler() functions have been redundantly
copied across multiple .c files.
Move these functions to helpers.h to enable reuse across tests,
eliminating around 250 lines of duplicate code.
Converge the error handling by using ksft_exit_fail_msg(), which is
functionally equivalent with err() within the selftest framework.
This change is a prerequisite for the upcoming xstate selftest, which
requires signal handling for registering and cleaning up handlers.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226010731.2456-2-chang.seok.bae@intel.com
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When building with clang, via:
make LLVM=1 -C tools/testing/selftests
...quite a few functions are variables are generating "unused" warnings.
Fix the warnings by deleting the unused items.
One item, the "nerrs" variable in vsdo_restorer.c's main(), is unused
but probably wants to be returned from main(), as a non-zero result.
That result is also unused right now, so another option would be to
delete it entirely, but this way, main() also gets fixed. It was missing
a return value.
Acked-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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Skip instead of failing when prerequisite conditions aren't fulfilled,
such as invalid xstate values etc.
Make the tests show as 'SKIP' when run:
make -C tools/testing/selftests/ TARGETS=x86 run_tests
...
# timeout set to 45
# selftests: x86: amx_64
# # xstate cpuid: invalid tile data size/offset: 0/0
ok 42 selftests: x86: amx_64 # SKIP
# timeout set to 45
# selftests: x86: lam_64
# # Unsupported LAM feature!
ok 43 selftests: x86: lam_64 # SKIP
...
In the AMX test, Move away from check_cpuid_xsave() and start using
arch_prctl() to find out if AMX support is present or not. In the
kernels where AMX isn't present, arch_prctl() returns -EINVAL, hence it is
backward compatible.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20240327111720.3509180-1-usama.anjum@collabora.com
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Include a test case to validate the XTILEDATA injection to the target.
Also, it ensures the kernel's ability to copy states between different
XSAVE formats.
Refactor the memcmp() code to be usable for the state validation.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20230227210504.18520-3-chang.seok.bae%40intel.com
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kselftest.h makes the __cpuid_count() macro available
to conveniently call the CPUID instruction.
Remove the local CPUID wrapper and use __cpuid_count()
from kselftest.h instead.
__cpuid_count() from kselftest.h is used instead of the
macro provided by the compiler since gcc v4.4 (via cpuid.h)
because the selftest needs to be supported with gcc v3.2,
the minimal required version for stable kernels.
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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Update the arch_prctl test to check the permission bitmap whether the
requested feature is added as expected or not.
Every non-dynamic feature that is enabled is permitted already for use.
TILECFG is not dynamic feature. Ensure the bit is always on from
ARCH_GET_XCOMP_PERM.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220129173647.27981-3-chang.seok.bae@intel.com
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XSAVE state is thread-local. The kernel switches between thread
state at context switch time. Generally, running a selftest for
a while will naturally expose it to some context switching and
and will test the XSAVE code.
Instead of just hoping that the tests get context-switched at
random times, force context-switches on purpose. Spawn off a few
userspace threads and force context-switches between them.
Ensure that the kernel correctly context switches each thread's
unique AMX state.
[ dhansen: bunches of cleanups ]
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211026122525.6EFD5758@davehans-spike.ostc.intel.com
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AMX TILEDATA is a very large XSAVE feature. It could have caused
nasty XSAVE buffer space waste in two places:
* Signal stacks
* Kernel task_struct->fpu buffers
To avoid this waste, neither of these buffers have AMX state by
default. The non-default features are called "dynamic" features.
There is an arch_prctl(ARCH_REQ_XCOMP_PERM) which allows a task
to declare that it wants to use AMX or other "dynamic" XSAVE
features. This arch_prctl() ensures that sufficient sigaltstack
space is available before it will succeed. It also expands the
task_struct buffer.
Functions of this test:
* Test arch_prctl(ARCH_REQ_XCOMP_PERM). Ensure that it checks for
proper sigaltstack sizing and that the sizing is enforced for
future sigaltstack calls.
* Ensure that ARCH_REQ_XCOMP_PERM is inherited across fork()
* Ensure that TILEDATA use before the prctl() is fatal
* Ensure that TILEDATA is cleared across fork()
Note: Generally, compiler support is needed to do something with
AMX. Instead, directly load AMX state from userspace with a
plain XSAVE. Do not depend on the compiler.
[ dhansen: bunches of cleanups ]
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211026122524.7BEDAA95@davehans-spike.ostc.intel.com
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