This is v4 of Aaron's "Clean up the supported xfeatures" series. Fix a bug where KVM treats/reports XTILE_CFG as supported without XTILE_DATA being supported if userspace queries the supported CPUID but doesn't request access to AMX, a.k.a. XTILE_DATA. If userspace reflects that CPUID info back into KVM, the resulting VM may use it verbatim and attempt to shove bad data into XCR0: XTILE_CFG and XTILE_DATA must be set/cleared as a pair in XCR0, despite being enumerated separately. This is effectively compile-tested only on my end. v4: - Apply the massaging _only to the XTILE case. - Add a build-time assertion to trigger a failure if a new dynamic XFeature comes along without updating kvm_get_filtered_xcr0(). v3: https://lore.kernel.org/all/20230224223607.1580880-1-aaronlewis@xxxxxxxxxx Aaron Lewis (4): KVM: x86: Add a helper to handle filtering of unpermitted XCR0 features KVM: selftests: Move XGETBV and XSETBV helpers to common code KVM: selftests: Add all known XFEATURE masks to common code KVM: selftests: Add test to verify KVM's supported XCR0 Sean Christopherson (2): KVM: x86: Filter out XTILE_CFG if XTILE_DATA isn't permitted KVM: selftests: Rework dynamic XFeature helper to take mask, not bit arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/x86.c | 4 +- arch/x86/kvm/x86.h | 29 ++++ tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/include/x86_64/processor.h | 69 +++++++-- .../selftests/kvm/lib/x86_64/processor.c | 17 ++- tools/testing/selftests/kvm/x86_64/amx_test.c | 62 +++----- .../selftests/kvm/x86_64/xcr0_cpuid_test.c | 132 ++++++++++++++++++ 8 files changed, 251 insertions(+), 65 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/xcr0_cpuid_test.c base-commit: 27d6845d258b67f4eb3debe062b7dacc67e0c393 -- 2.40.0.348.gf938b09366-goog
