Be a good citizen and don't allow any of the supported AVX-512
xfeatures[1] to be set if they can't all be set. That way userspace or
a guest doesn't fail if it attempts to set them in XCR0.
It's important to note that in order to set any of the AVX-512
xfeatures, the SSE[bit-1] and AVX[bit-2] must also be set.
[1] CPUID.(EAX=0DH,ECX=0):EAX.OPMASK[bit-5]
CPUID.(EAX=0DH,ECX=0):EAX.ZMM_Hi256[bit-6]
CPUID.(EAX=0DH,ECX=0):EAX.ZMM_Hi16_ZMM[bit-7]
Suggested-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Aaron Lewis <aaronlewis@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2431c46d456b4..89ad8cd865173 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -862,6 +862,10 @@ static u64 sanitize_xcr0(u64 xcr0) {
if ((xcr0 & mask) != mask)
xcr0 &= ~mask;
+ mask = XFEATURE_MASK_SSE | XFEATURE_MASK_YMM | XFEATURE_MASK_AVX512;
+ if ((xcr0 & mask) != mask)
+ xcr0 &= ~XFEATURE_MASK_AVX512;
+
return xcr0;
}
--
2.39.0.314.g84b9a713c41-goog
