2 files changed, 18 insertions, 4 deletions

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index f5e343cb06b..6d0bd7aab92 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -244,6 +244,7 @@ struct kvm_vcpu {
         struct mutex mutex;
         int   cpu;
         int   launched;
+        u64 host_tsc;
         struct kvm_run *run;
         int interrupt_window_open;
         unsigned long irq_summary; /* bit vector: 1 per word in irq_pending */
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 0542d3357ce..ca2642fc091 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -459,7 +459,6 @@ static void init_vmcb(struct vmcb *vmcb)
 {
         struct vmcb_control_area *control = &vmcb->control;
         struct vmcb_save_area *save = &vmcb->save;
-        u64 tsc;
 
         control->intercept_cr_read =    INTERCEPT_CR0_MASK |
                                         INTERCEPT_CR3_MASK |
@@ -517,8 +516,7 @@ static void init_vmcb(struct vmcb *vmcb)
 
         control->iopm_base_pa = iopm_base;
         control->msrpm_base_pa = msrpm_base;
-        rdtscll(tsc);
-        control->tsc_offset = -tsc;
+        control->tsc_offset = 0;
         control->int_ctl = V_INTR_MASKING_MASK;
 
         init_seg(&save->es);
@@ -606,11 +604,26 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
 
 static void svm_vcpu_load(struct kvm_vcpu *vcpu)
 {
-        get_cpu();
+        int cpu;
+
+        cpu = get_cpu();
+        if (unlikely(cpu != vcpu->cpu)) {
+                u64 tsc_this, delta;
+
+                /*
+                 * Make sure that the guest sees a monotonically
+                 * increasing TSC.
+                 */
+                rdtscll(tsc_this);
+                delta = vcpu->host_tsc - tsc_this;
+                vcpu->svm->vmcb->control.tsc_offset += delta;
+                vcpu->cpu = cpu;
+        }
 }
 
 static void svm_vcpu_put(struct kvm_vcpu *vcpu)
 {
+        rdtscll(vcpu->host_tsc);
         put_cpu();
 }