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>

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

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);

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++)

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;