Commit 48434c20 authored Aug 19, 2010 by Zachary Amsden Committed by Avi Kivity Oct 24, 2010

KVM: x86: Fix deep C-state TSC desynchronization



When CPUs with unstable TSCs enter deep C-state, TSC may stop
running.  This causes us to require resynchronization.  Since
we can't tell when this may potentially happen, we assume the
worst by forcing re-compensation for it at every point the VCPU
task is descheduled.

Signed-off-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

parent e48672fa

arch/x86/kvm/x86.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1866,7 +1866,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
		}

		kvm_x86_ops->vcpu_load(vcpu, cpu);
		if (unlikely(vcpu->cpu != cpu)) {
		if (unlikely(vcpu->cpu != cpu) \|\| check_tsc_unstable()) {
		/* Make sure TSC doesn't go backwards */
		s64 tsc_delta = !vcpu->arch.last_host_tsc ? 0 :
		native_read_tsc() - vcpu->arch.last_host_tsc;

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