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

Synthetic timers MSRs (HV_X64_MSR_STIMER[0-3]_CONFIG,
HV_X64_MSR_STIMER[0-3]_COUNT) are only available to guest when
HV_MSR_SYNTIMER_AVAILABLE bit is exposed.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-13-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/hyperv.c

@@ -1236,6 +1236,16 @@ static bool hv_check_msr_access(struct kvm_vcpu_hv *hv_vcpu, u32 msr)
 	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
 		return hv_vcpu->cpuid_cache.features_eax &
 			HV_MSR_SYNIC_AVAILABLE;
+	case HV_X64_MSR_STIMER0_CONFIG:
+	case HV_X64_MSR_STIMER1_CONFIG:
+	case HV_X64_MSR_STIMER2_CONFIG:
+	case HV_X64_MSR_STIMER3_CONFIG:
+	case HV_X64_MSR_STIMER0_COUNT:
+	case HV_X64_MSR_STIMER1_COUNT:
+	case HV_X64_MSR_STIMER2_COUNT:
+	case HV_X64_MSR_STIMER3_COUNT:
+		return hv_vcpu->cpuid_cache.features_eax &
+			HV_MSR_SYNTIMER_AVAILABLE;
 	default:
 		break;
 	}