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@xxxxxxxxxx>
---
Not sure about the FIXME, and it might motivate someone to redo the
implicit checking as well :)
arch/x86/kvm/lapic.c | 37 +++++++++++++++++++++----------------
1 file changed, 21 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index b8345dd..a3cf68b 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1034,6 +1034,26 @@ 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;
@@ -1538,23 +1558,8 @@ 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);
--
2.1.0
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