[PATCH 01/33] KVM: SVM: support writing 0 to K8 performance counter control registers

[Avi Kivity]

From: Joerg Roedel <joerg.roedel@xxxxxxx>

This lets SVM ignore writes of the value 0 to the performance counter control
registers.  Thus enabling them will still fail in the guest, but a write of 0
which keeps them disabled is accepted.  This is required to boot Windows
Vista 64bit.

[avi: avoid fall-thru in switch statement]

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
Signed-off-by: Markus Rechberger <markus.rechberger@xxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>
---
 drivers/kvm/svm.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 9f8564a..839a75f 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -1155,7 +1155,20 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data)
 	case MSR_IA32_SYSENTER_ESP:
 		svm->vmcb->save.sysenter_esp = data;
 		break;
+	case MSR_K7_EVNTSEL0:
+	case MSR_K7_EVNTSEL1:
+	case MSR_K7_EVNTSEL2:
+	case MSR_K7_EVNTSEL3:
+		/*
+		 * only support writing 0 to the performance counters for now
+		 * to make Windows happy. Should be replaced by a real
+		 * performance counter emulation later.
+		 */
+		if (data != 0)
+			goto unhandled;
+		break;
 	default:
+	unhandled:
 		return kvm_set_msr_common(vcpu, ecx, data);
 	}
 	return 0;
-- 
1.5.3.7

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