KVM: Migrate lapic hrtimer when vcpu moves to another cpu

This reduces overhead by accessing cachelines from the wrong node, as well
as simplifying locking.

[Qing: fix for inactive or expired one-shot timer]

Signed-off-by: Yaozu (Eddie) Dong <Eddie.Dong@intel.com>
Signed-off-by: Qing He <qing.he@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

4 files changed, 19 insertions, 1 deletions

diff --git a/drivers/kvm/irq.h b/drivers/kvm/irq.h
index 87baf7e69ea..f324cfb4008 100644
--- a/drivers/kvm/irq.h
+++ b/drivers/kvm/irq.h
@@ -158,5 +158,6 @@ void kvm_apic_timer_intr_post(struct kvm_vcpu *vcpu, int vec);
 void kvm_timer_intr_post(struct kvm_vcpu *vcpu, int vec);
 void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu);
 void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu);
+void kvm_migrate_apic_timer(struct kvm_vcpu *vcpu);
 
 #endif
diff --git a/drivers/kvm/lapic.c b/drivers/kvm/lapic.c
index 490d4939dba..2706ec36c25 100644
--- a/drivers/kvm/lapic.c
+++ b/drivers/kvm/lapic.c
@@ -979,3 +979,17 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu)
         update_divide_count(apic);
         start_apic_timer(apic);
 }
+
+void kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
+{
+        struct kvm_lapic *apic = vcpu->apic;
+        struct hrtimer *timer;
+
+        if (!apic)
+                return;
+
+        timer = &apic->timer.dev;
+        if (hrtimer_cancel(timer))
+                hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
+}
+EXPORT_SYMBOL_GPL(kvm_migrate_apic_timer);
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 00119ec4166..3de9ec35ebf 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -633,6 +633,7 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
                 delta = vcpu->host_tsc - tsc_this;
                 svm->vmcb->control.tsc_offset += delta;
                 vcpu->cpu = cpu;
+                kvm_migrate_apic_timer(vcpu);
         }
 
         for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index eeecadf5da4..f4618b9edf9 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -441,8 +441,10 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
         u64 phys_addr = __pa(vmx->vmcs);
         u64 tsc_this, delta;
 
-        if (vcpu->cpu != cpu)
+        if (vcpu->cpu != cpu) {
                 vcpu_clear(vmx);
+                kvm_migrate_apic_timer(vcpu);
+        }
 
         if (per_cpu(current_vmcs, cpu) != vmx->vmcs) {
                 u8 error;