x86/kvm/hyper-v: recommend using eVMCS only when it is enabled

We shouldn't probably be suggesting using Enlightened VMCS when it's not
enabled (not supported from guest's point of view). Hyper-V on KVM seems
to be fine either way but let's be consistent.

Fixes: 2bc39970e932 ("x86/kvm/hyper-v: Introduce KVM_GET_SUPPORTED_HV_CPUID")
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 4840f5b..4730fca 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1850,7 +1850,8 @@ int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
                        ent->eax |= HV_X64_RELAXED_TIMING_RECOMMENDED;
                        ent->eax |= HV_X64_CLUSTER_IPI_RECOMMENDED;
                        ent->eax |= HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED;
-                       ent->eax |= HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
+                       if (evmcs_ver)
+                               ent->eax |= HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
 
                        /*
                         * Default number of spinlock retry attempts, matches