The tsc_offset adjustment in svm_vcpu_load is executed unconditionally even if Linux considers the host tsc as stable. This causes a Linux guest detecting an unstable tsc in any case. This patch removes the tsc_offset adjustment if the host tsc is stable. The guest will now get the benefit of a stable tsc too.
Signed-off-by: Joerg Roedel <[email protected]> --- arch/x86/kvm/svm.c | 18 ++++++++++-------- 1 files changed, 10 insertions(+), 8 deletions(-) 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; -- 1.6.5.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
