KVM: SVM: support writing 0 to K8 performance counter control registers

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@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 442ca818c5a9..ef21804a5c5c 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;