KVM: SVM: Adjust tsc_offset only if tsc_unstable

Commit Message

Joerg Roedel Dec. 14, 2009, 11:22 a.m. UTC

None

Patch

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 3de0b37..cb04378 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -767,14 +767,16 @@  static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	if (unlikely(cpu != vcpu->cpu)) {
 		u64 delta;
 
-		/*
-		 * Make sure that the guest sees a monotonically
-		 * increasing TSC.
-		 */
-		delta = vcpu->arch.host_tsc - native_read_tsc();
-		svm->vmcb->control.tsc_offset += delta;
-		if (is_nested(svm))
-			svm->nested.hsave->control.tsc_offset += delta;
+		if (check_tsc_unstable()) {
+			/*
+			 * Make sure that the guest sees a monotonically
+			 * increasing TSC.
+			 */
+			delta = vcpu->arch.host_tsc - native_read_tsc();
+			svm->vmcb->control.tsc_offset += delta;
+			if (is_nested(svm))
+				svm->nested.hsave->control.tsc_offset += delta;
+		}
 		vcpu->cpu = cpu;
 		kvm_migrate_timers(vcpu);
 		svm->asid_generation = 0;