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>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/kvm/lapic.c b/drivers/kvm/lapic.c
index 490d4939dba7..2706ec36c258 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);