KVM: VMX: Fake emulate Intel perfctr MSRs

Older linux guests (in this case, 2.6.9) can attempt to
access the performance counter MSRs without a fixup section, and injecting
a GPF kills the guest.  Work around by allowing the guest to write those MSRs.

Tested by me on RHEL-4 i386 and x86_64 guests, as well as F-9 guests.

Signed-off-by: Chris Lalancette <clalance@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6a3a4038f3b9..d493a97e7887 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -921,6 +921,18 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
         case MSR_IA32_TIME_STAMP_COUNTER:
                 guest_write_tsc(data);
                 break;
+        case MSR_P6_PERFCTR0:
+        case MSR_P6_PERFCTR1:
+        case MSR_P6_EVNTSEL0:
+        case MSR_P6_EVNTSEL1:
+                /*
+                 * Just discard all writes to the performance counters; this
+                 * should keep both older linux and windows 64-bit guests
+                 * happy
+                 */
+                pr_unimpl(vcpu, "unimplemented perfctr wrmsr: 0x%x data 0x%llx\n", msr_index, data);
+
+                break;
         default:
                 vmx_load_host_state(vmx);
                 msr = find_msr_entry(vmx, msr_index);