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| author |   Joerg Roedel <joerg.roedel@amd.com> | 2009-12-14 12:22:20 +0100 |
|---|---|---|
| committer |   Marcelo Tosatti <mtosatti@redhat.com> | 2010-03-01 12:35:41 -0300 |
| commit | 953899b659adce62cbe83d6a7527550ab8797c48 (patch) | |
| tree | 5eb465ea6b419ba58d310fec6c3e619fd4dd148d /arch | |
| parent | KVM: VMX: Add instruction rdtscp support for guest (diff) | |
| download | linux-dev-953899b659adce62cbe83d6a7527550ab8797c48.tar.xz linux-dev-953899b659adce62cbe83d6a7527550ab8797c48.zip | |
KVM: SVM: Adjust tsc_offset only if tsc_unstable
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | 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 7f4e225feebf..b373ae6fb974 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -765,14 +765,16 @@ 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; |