diff options
| author | Joerg Roedel <joerg.roedel@amd.com> | 2010-10-28 16:48:13 -0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-11-22 10:47:34 -0800 |
| commit | cd80c840270c7b57bc38d6e2e1647e84ce23075d (patch) | |
| tree | 14a8ed02bde77ca9b2e5c5ecd8fdcbe690948475 | |
| parent | ffc109c28a6a4cb5047df82b1d18ad7a13d3e247 (diff) | |
KVM: SVM: Adjust tsc_offset only if tsc_unstable
commit 953899b659adce62cbe83d6a7527550ab8797c48 upstream.
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 <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | arch/x86/kvm/svm.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 52ffdc68a60a..925c326cab5b 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -795,17 +795,18 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) int i; if (unlikely(cpu != vcpu->cpu)) { - u64 tsc_this, delta; - - /* - * Make sure that the guest sees a monotonically - * increasing TSC. - */ - rdtscll(tsc_this); - delta = vcpu->arch.host_tsc - tsc_this; - svm->vmcb->control.tsc_offset += delta; - if (is_nested(svm)) - svm->nested.hsave->control.tsc_offset += delta; + u64 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; |