Following patches would be even uglier if inject_lock didn't go away. Patch changes the virtual wire comment to better describe our situation.
Signed-off-by: Radim Krčmář <[email protected]> --- arch/x86/kvm/i8254.c | 67 ++++++++++++++++++++++------------------------------ arch/x86/kvm/i8254.h | 3 +-- 2 files changed, 29 insertions(+), 41 deletions(-) diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index de5f5018026f..a137eb381012 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -236,16 +236,13 @@ static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian) { struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state, irq_ack_notifier); - int value; - spin_lock(&ps->inject_lock); + atomic_set(&ps->irq_ack, 1); if (atomic_add_unless(&ps->pending, -1, 0)) /* in this case, we had multiple outstanding pit interrupts * that we needed to inject. Reinject */ queue_kthread_work(&ps->pit->worker, &ps->pit->expired); - ps->irq_ack = 1; - spin_unlock(&ps->inject_lock); } void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu) @@ -276,34 +273,25 @@ static void pit_do_work(struct kthread_work *work) struct kvm_vcpu *vcpu; int i; struct kvm_kpit_state *ps = &pit->pit_state; - int inject = 0; - /* Try to inject pending interrupts when - * last one has been acked. + if (!atomic_xchg(&ps->irq_ack, 0)) + return; + + kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1, false); + kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0, false); + + /* + * Provides NMI watchdog support via Virtual Wire mode. + * The route is: PIT -> LVT0 in NMI mode. + * + * Note: Our Virtual Wire implementation does not follow + * the MP specification. We propagate a PIT interrupt to all + * VCPUs and only when LVT0 is in NMI mode. The interrupt can + * also be simultaneously delivered through PIC and IOAPIC. */ - spin_lock(&ps->inject_lock); - if (ps->irq_ack) { - ps->irq_ack = 0; - inject = 1; - } - spin_unlock(&ps->inject_lock); - if (inject) { - kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1, false); - kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0, false); - - /* - * Provides NMI watchdog support via Virtual Wire mode. - * The route is: PIT -> PIC -> LVT0 in NMI mode. - * - * Note: Our Virtual Wire implementation is simplified, only - * propagating PIT interrupts to all VCPUs when they have set - * LVT0 to NMI delivery. Other PIC interrupts are just sent to - * VCPU0, and only if its LVT0 is in EXTINT mode. - */ - if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0) - kvm_for_each_vcpu(i, vcpu, kvm) - kvm_apic_nmi_wd_deliver(vcpu); - } + if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0) + kvm_for_each_vcpu(i, vcpu, kvm) + kvm_apic_nmi_wd_deliver(vcpu); } static enum hrtimer_restart pit_timer_fn(struct hrtimer *data) @@ -323,6 +311,12 @@ static enum hrtimer_restart pit_timer_fn(struct hrtimer *data) return HRTIMER_NORESTART; } +static void kvm_pit_reset_reinject(struct kvm_pit *pit) +{ + atomic_set(&pit->pit_state.pending, 0); + atomic_set(&pit->pit_state.irq_ack, 1); +} + static void create_pit_timer(struct kvm *kvm, u32 val, int is_period) { struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state; @@ -345,8 +339,7 @@ static void create_pit_timer(struct kvm *kvm, u32 val, int is_period) ps->timer.function = pit_timer_fn; ps->kvm = ps->pit->kvm; - atomic_set(&ps->pending, 0); - ps->irq_ack = 1; + kvm_pit_reset_reinject(ps->pit); /* * Do not allow the guest to program periodic timers with small @@ -646,18 +639,15 @@ void kvm_pit_reset(struct kvm_pit *pit) } mutex_unlock(&pit->pit_state.lock); - atomic_set(&pit->pit_state.pending, 0); - pit->pit_state.irq_ack = 1; + kvm_pit_reset_reinject(pit); } static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask) { struct kvm_pit *pit = container_of(kimn, struct kvm_pit, mask_notifier); - if (!mask) { - atomic_set(&pit->pit_state.pending, 0); - pit->pit_state.irq_ack = 1; - } + if (!mask) + kvm_pit_reset_reinject(pit); } static const struct kvm_io_device_ops pit_dev_ops = { @@ -691,7 +681,6 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags) mutex_init(&pit->pit_state.lock); mutex_lock(&pit->pit_state.lock); - spin_lock_init(&pit->pit_state.inject_lock); pid = get_pid(task_tgid(current)); pid_nr = pid_vnr(pid); diff --git a/arch/x86/kvm/i8254.h b/arch/x86/kvm/i8254.h index c84990b42b5b..f8cf4b84f435 100644 --- a/arch/x86/kvm/i8254.h +++ b/arch/x86/kvm/i8254.h @@ -33,8 +33,7 @@ struct kvm_kpit_state { u32 speaker_data_on; struct mutex lock; struct kvm_pit *pit; - spinlock_t inject_lock; - unsigned long irq_ack; + atomic_t irq_ack; struct kvm_irq_ack_notifier irq_ack_notifier; }; -- 2.7.0
