KVM: x86: hyper-v: Cache HYPERV_CPUID_NESTED_FEATURES CPUID leaf

KVM has to check guest visible HYPERV_CPUID_NESTED_FEATURES.EBX CPUID
leaf to know which Enlightened VMCS definition to use (original or 2022
update). Cache the leaf along with other Hyper-V CPUID feature leaves
to make the check quick.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220830133737.1539624-12-vkuznets@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2c96c43..9411348 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -615,6 +615,8 @@ struct kvm_vcpu_hv {
                u32 enlightenments_eax; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EAX */
                u32 enlightenments_ebx; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EBX */
                u32 syndbg_cap_eax; /* HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX */
+               u32 nested_eax; /* HYPERV_CPUID_NESTED_FEATURES.EAX */
+               u32 nested_ebx; /* HYPERV_CPUID_NESTED_FEATURES.EBX */
        } cpuid_cache;
 };
 

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index bf4729e..a7478b6 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2018,6 +2018,12 @@ void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu, bool hyperv_enabled)
        entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES);
        if (entry)
                hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax;
+
+       entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_NESTED_FEATURES);
+       if (entry) {
+               hv_vcpu->cpuid_cache.nested_eax = entry->eax;
+               hv_vcpu->cpuid_cache.nested_ebx = entry->ebx;
+       }
 }
 
 int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce)