KVM: x86: svm: report MSR_IA32_MCG_EXT_CTL as unsupported

AMD doesn't seem to implement MSR_IA32_MCG_EXT_CTL and svm code in kvm
knows nothing about it, however, this MSR is among emulated_msrs and
thus returned with KVM_GET_MSR_INDEX_LIST. The consequent KVM_GET_MSRS,
of course, fails.

Report the MSR as unsupported to not confuse userspace.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index e4f18a305ef6..c4377f02a33b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5840,6 +5840,13 @@ static bool svm_cpu_has_accelerated_tpr(void)
 
 static bool svm_has_emulated_msr(int index)
 {
+	switch (index) {
+	case MSR_IA32_MCG_EXT_CTL:
+		return false;
+	default:
+		break;
+	}
+
 	return true;
 }