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KVM: x86: add apic_timer_expired() 

Make the code reusable.

If the timer was already pending, we shouldn't be waiting in a queue,
so wake_up can be skipped, simplifying the path.

There is no 'reinject' case => the comment is removed.
Current race behaves correctly.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Radim Krčmář 2014-10-10 19:15:08 +02:00 committed by Paolo Bonzini
parent 91690bf32e
commit 5d87db7119
1 changed files with 21 additions and 16 deletions
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37
arch/x86/kvm/lapic.c
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@ -1050,6 +1050,26 @@ static void update_divide_count(struct kvm_lapic *apic)
apic->divide_count);
}
static void apic_timer_expired(struct kvm_lapic *apic)
{
struct kvm_vcpu *vcpu = apic->vcpu;
wait_queue_head_t *q = &vcpu->wq;
/*
* Note: KVM_REQ_PENDING_TIMER is implicitly checked in
* vcpu_enter_guest.
*/
if (atomic_read(&apic->lapic_timer.pending))
return;
atomic_inc(&apic->lapic_timer.pending);
/* FIXME: this code should not know anything about vcpus */
kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
if (waitqueue_active(q))
wake_up_interruptible(q);
}
static void start_apic_timer(struct kvm_lapic *apic)
{
ktime_t now;
@ -1554,23 +1574,8 @@ static enum hrtimer_restart apic_timer_fn(struct hrtimer *data)
{
struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer);
struct kvm_lapic *apic = container_of(ktimer, struct kvm_lapic, lapic_timer);
struct kvm_vcpu *vcpu = apic->vcpu;
wait_queue_head_t *q = &vcpu->wq;
/*
* There is a race window between reading and incrementing, but we do
* not care about potentially losing timer events in the !reinject
* case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked
* in vcpu_enter_guest.
*/
if (!atomic_read(&ktimer->pending)) {
atomic_inc(&ktimer->pending);
/* FIXME: this code should not know anything about vcpus */
kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
}
if (waitqueue_active(q))
wake_up_interruptible(q);
apic_timer_expired(apic);
if (lapic_is_periodic(apic)) {
hrtimer_add_expires_ns(&ktimer->timer, ktimer->period);