From: Zachary Amsden Date: Fri, 20 Aug 2010 08:07:24 +0000 (-1000) Subject: KVM: x86: Fix deep C-state TSC desynchronization X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=48434c20e18d59001469699fcaaf9cf30b815a20;p=linux-beck.git 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 Signed-off-by: Marcelo Tosatti --- diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 468fafaed1ae..9396b3f2c594 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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;