From 5d87db711937019cb8eba1137c37573d7a604be8 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Date: Fri, 10 Oct 2014 19:15:08 +0200 Subject: [PATCH] KVM: x86: add apic_timer_expired() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Paolo Bonzini --- 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 ee04adf6c73..1ebd7ff33ac 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -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); -- 2.41.0