[00/11] KVM: selftests: AVX support + fixes

Message

Sean Christopherson Oct. 3, 2024, 11:43 p.m. UTC

Enable CR4.OSXSAVE and XCR0.AVX by default when creating selftests vCPUs
in order to play nice with compilers that have been configured to enable
-march=x86-64-v3 by default.

While it would be easier to force v2 (or earlier), there are enough tests
that want XCR0 configured that it will (hopefully) be a net postive to
enable all XCR0 features by default.

The only real hiccup is the CR4/CPUID sync test, which disables CR4.OSXSAVE
to verify KVM toggles the associated CPUID bit.  And if it calls memset()
while OSXAVE is disabled, kablooie.  Fixing that requires a bit of assembly,
but overall I think it's worth carrying a few lines of assembly in order to
gain test coverage for running AVX instructions in guests, and boy are
compilers good at abusing AVX :-)

Fix a few bugs/warts found along the way.  Notably, the CPUID test has an
array out-of-bounds bug that can result in false passes (I only noticed
because it was getting a false pass on gcc).

Sean Christopherson (11):
  KVM: selftests: Fix out-of-bounds reads in CPUID test's array lookups
  KVM: selftests: Precisely mask off dynamic fields in CPUID test
  KVM: selftests: Mask off OSPKE and OSXSAVE when comparing CPUID
    entries
  KVM: selftests: Rework OSXSAVE CR4=>CPUID test to play nice with AVX
    insns
  KVM: selftests: Configure XCR0 to max supported value by default
  KVM: selftests: Verify XCR0 can be "downgraded" and "upgraded"
  KVM: selftests: Drop manual CR4.OSXSAVE enabling from CR4/CPUID sync
    test
  KVM: selftests: Drop manual XCR0 configuration from AMX test
  KVM: selftests: Drop manual XCR0 configuration from state test
  KVM: selftests: Drop manual XCR0 configuration from SEV smoke test
  KVM: selftests: Ensure KVM supports AVX for SEV-ES VMSA FPU test

 .../selftests/kvm/include/x86_64/processor.h  |  5 ++
 .../selftests/kvm/lib/x86_64/processor.c      | 24 +++++++
 tools/testing/selftests/kvm/x86_64/amx_test.c | 23 ++-----
 .../testing/selftests/kvm/x86_64/cpuid_test.c | 67 ++++++++++++-------
 .../kvm/x86_64/cr4_cpuid_sync_test.c          | 53 +++++++++------
 .../selftests/kvm/x86_64/sev_smoke_test.c     | 19 ++----
 .../testing/selftests/kvm/x86_64/state_test.c |  5 --
 .../selftests/kvm/x86_64/xcr0_cpuid_test.c    | 11 ++-
 8 files changed, 122 insertions(+), 85 deletions(-)


base-commit: efbc6bd090f48ccf64f7a8dd5daea775821d57ec