KVM: x86: hyper-v: Honor HV_MSR_SYNIC_AVAILABLE privilege bit

SynIC MSRs (HV_X64_MSR_SCONTROL, HV_X64_MSR_SVERSION, HV_X64_MSR_SIEFP,
HV_X64_MSR_SIMP, HV_X64_MSR_EOM, HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15)
are only available to guest when HV_MSR_SYNIC_AVAILABLE bit is exposed.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-12-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/hyperv.c

@@ -1228,6 +1228,14 @@ static bool hv_check_msr_access(struct kvm_vcpu_hv *hv_vcpu, u32 msr)
 	case HV_X64_MSR_REFERENCE_TSC:
 		return hv_vcpu->cpuid_cache.features_eax &
 			HV_MSR_REFERENCE_TSC_AVAILABLE;
+	case HV_X64_MSR_SCONTROL:
+	case HV_X64_MSR_SVERSION:
+	case HV_X64_MSR_SIEFP:
+	case HV_X64_MSR_SIMP:
+	case HV_X64_MSR_EOM:
+	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
+		return hv_vcpu->cpuid_cache.features_eax &
+			HV_MSR_SYNIC_AVAILABLE;
 	default:
 		break;
 	}