x86/cpu/amd, kvm: Satisfy guest kernel reads of IC_CFG MSR

The kernel accesses IC_CFG MSR (0xc0011021) on AMD because it
checks whether the way access filter is enabled on some F15h
models, and, if so, disables it.

kvm doesn't handle that MSR access and complains about it, which
can get really noisy in dmesg when one starts kvm guests all the
time for testing. And it is useless anyway - guest kernel
shouldn't be doing such changes anyway so tell it that that
filter is disabled.

Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Paolo Bonzini <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 83a1c643f9a5..58b64c17c4a8 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3053,6 +3053,23 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_IA32_UCODE_REV:
 		msr_info->data = 0x01000065;
 		break;
+	case MSR_F15H_IC_CFG: {
+
+		int family, model;
+
+		family = guest_cpuid_family(vcpu);
+		model  = guest_cpuid_model(vcpu);
+
+		if (family < 0 || model < 0)
+			return kvm_get_msr_common(vcpu, msr_info);
+
+		msr_info->data = 0;
+
+		if (family == 0x15 &&
+		    (model >= 0x2 && model < 0x20))
+			msr_info->data = 0x1E;
+		}
+		break;
 	default:
 		return kvm_get_msr_common(vcpu, msr_info);
 	}