| Message ID | 20240517173926.965351-44-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: CPUID overhaul, fixes, and caching | expand |
On Fri, 2024-05-17 at 10:39 -0700, Sean Christopherson wrote: > When making runtime CPUID updates, change OSXSAVE and OSPKE even if their > respective base features (XSAVE, PKU) are not supported by the host. KVM > already incorporates host support in the vCPU's effective reserved CR4 bits. > I.e. OSXSAVE and OSPKE can be set if and only if the host supports them. > > And conversely, since KVM's ABI is that KVM owns the dynamic OS feature > flags, clearing them when they obviously aren't supported and thus can't > be enabled is arguably a fix. > > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/cpuid.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 8256fc657c6b..552e65ba5efa 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -336,10 +336,8 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu) > > best = kvm_find_cpuid_entry(vcpu, 1); > if (best) { > - /* Update OSXSAVE bit */ > - if (boot_cpu_has(X86_FEATURE_XSAVE)) > - cpuid_entry_change(best, X86_FEATURE_OSXSAVE, > - kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE)); > + cpuid_entry_change(best, X86_FEATURE_OSXSAVE, > + kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE)); > > cpuid_entry_change(best, X86_FEATURE_APIC, > vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE); > @@ -351,7 +349,7 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu) > } > > best = kvm_find_cpuid_entry_index(vcpu, 7, 0); > - if (best && boot_cpu_has(X86_FEATURE_PKU)) > + if (best) > cpuid_entry_change(best, X86_FEATURE_OSPKE, > kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE)); > Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Best regards, Maxim Levitsky
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 8256fc657c6b..552e65ba5efa 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -336,10 +336,8 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu) best = kvm_find_cpuid_entry(vcpu, 1); if (best) { - /* Update OSXSAVE bit */ - if (boot_cpu_has(X86_FEATURE_XSAVE)) - cpuid_entry_change(best, X86_FEATURE_OSXSAVE, - kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE)); + cpuid_entry_change(best, X86_FEATURE_OSXSAVE, + kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE)); cpuid_entry_change(best, X86_FEATURE_APIC, vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE); @@ -351,7 +349,7 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu) } best = kvm_find_cpuid_entry_index(vcpu, 7, 0); - if (best && boot_cpu_has(X86_FEATURE_PKU)) + if (best) cpuid_entry_change(best, X86_FEATURE_OSPKE, kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE));
When making runtime CPUID updates, change OSXSAVE and OSPKE even if their respective base features (XSAVE, PKU) are not supported by the host. KVM already incorporates host support in the vCPU's effective reserved CR4 bits. I.e. OSXSAVE and OSPKE can be set if and only if the host supports them. And conversely, since KVM's ABI is that KVM owns the dynamic OS feature flags, clearing them when they obviously aren't supported and thus can't be enabled is arguably a fix. Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/cpuid.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)