[PATCH v3 04/15] KVM: VMX: Check KVM CPU caps, not just VMX MSR support, for XSAVE enabling

From: Sean Christopherson
Date: Tue Aug 15 2023 - 16:38:24 EST


Check KVM CPU capabilities instead of raw VMX support for XSAVES when
determining whether or not XSAVER can/should be exposed to the guest.
Practically speaking, it's nonsensical/impossible for a CPU to support
"enable XSAVES" without XSAVES being supported natively. The real
motivation for checking kvm_cpu_cap_has() is to allow using the governed
feature's standard check-and-set logic.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1bf85bd53416..78f292b7e2c5 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7745,7 +7745,7 @@ static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
* to the guest. XSAVES depends on CR4.OSXSAVE, and CR4.OSXSAVE can be
* set if and only if XSAVE is supported.
*/
- vcpu->arch.xsaves_enabled = cpu_has_vmx_xsaves() &&
+ vcpu->arch.xsaves_enabled = kvm_cpu_cap_has(X86_FEATURE_XSAVES) &&
boot_cpu_has(X86_FEATURE_XSAVE) &&
guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) &&
guest_cpuid_has(vcpu, X86_FEATURE_XSAVES);
--
2.41.0.694.ge786442a9b-goog