KVM does not implement MSR_IA32_TSX_CTRL, so it must not be presented
to the guests. It is also confusing to have !ARCH_CAP_TSX_CTRL_MSR &&
!RTM && ARCH_CAP_TAA_NO: lack of MSR_IA32_TSX_CTRL suggests TSX was not
hidden (it actually was), yet the value says that TSX is not vulnerable
to microarchitectural data sampling. Fix both.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5d530521f11d..6ea735d632e9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1327,12 +1327,18 @@ static u64 kvm_get_arch_capabilities(void)
* If TSX is disabled on the system, guests are also mitigated against
* TAA and clear CPU buffer mitigation is not required for guests.
*/
- if (boot_cpu_has_bug(X86_BUG_TAA) && boot_cpu_has(X86_FEATURE_RTM) &&
- (data & ARCH_CAP_TSX_CTRL_MSR))
+ if (!boot_cpu_has(X86_FEATURE_RTM))
+ data &= ~ARCH_CAP_TAA_NO;
+ else if (!boot_cpu_has_bug(X86_BUG_TAA))
+ data |= ARCH_CAP_TAA_NO;
+ else if (data & ARCH_CAP_TSX_CTRL_MSR)
data &= ~ARCH_CAP_MDS_NO;
+ /* KVM does not emulate MSR_IA32_TSX_CTRL. */
+ data &= ~ARCH_CAP_TSX_CTRL_MSR;
return data;
}
+EXPORT_SYMBOL_GPL(kvm_get_arch_capabilities);
static int kvm_get_msr_feature(struct kvm_msr_entry *msr)
{
--
1.8.3.1
