From 71474e2f0f439b83b7b53ee6e9cf4f44c15b5806 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Date: Wed, 2 Mar 2016 22:56:45 +0100 Subject: KVM: i8254: remove notifiers from PIT discard policy MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Discard policy doesn't rely on information from notifiers, so we don't need to register notifiers unconditionally. We kept correct counts in case userspace switched between policies during runtime, but that can be avoided by reseting the state. Signed-off-by: Radim Krčmář Signed-off-by: Paolo Bonzini --- arch/x86/kvm/i8254.c | 38 +++++++++++++++++++++++++++----------- 1 file changed, 27 insertions(+), 11 deletions(-) (limited to 'arch/x86/kvm/i8254.c') diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index b8582fbe4fcf..7a2f14bdf4b5 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -225,7 +225,7 @@ static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian) * inc(pending) in pit_timer_fn and xchg(irq_ack, 0) in pit_do_work. */ smp_mb(); - if (atomic_dec_if_positive(&ps->pending) > 0 && ps->reinject) + if (atomic_dec_if_positive(&ps->pending) > 0) queue_kthread_work(&ps->pit->worker, &ps->pit->expired); } @@ -301,6 +301,27 @@ static inline void kvm_pit_reset_reinject(struct kvm_pit *pit) atomic_set(&pit->pit_state.irq_ack, 1); } +void kvm_pit_set_reinject(struct kvm_pit *pit, bool reinject) +{ + struct kvm_kpit_state *ps = &pit->pit_state; + struct kvm *kvm = pit->kvm; + + if (ps->reinject == reinject) + return; + + if (reinject) { + /* The initial state is preserved while ps->reinject == 0. */ + kvm_pit_reset_reinject(pit); + kvm_register_irq_ack_notifier(kvm, &ps->irq_ack_notifier); + kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier); + } else { + kvm_unregister_irq_ack_notifier(kvm, &ps->irq_ack_notifier); + kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier); + } + + ps->reinject = reinject; +} + static void create_pit_timer(struct kvm_pit *pit, u32 val, int is_period) { struct kvm_kpit_state *ps = &pit->pit_state; @@ -681,15 +702,14 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags) pit_state = &pit->pit_state; pit_state->pit = pit; hrtimer_init(&pit_state->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); + pit_state->irq_ack_notifier.gsi = 0; pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq; - kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier); - pit_state->reinject = true; + pit->mask_notifier.func = pit_mask_notifer; kvm_pit_reset(pit); - pit->mask_notifier.func = pit_mask_notifer; - kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier); + kvm_pit_set_reinject(pit, true); kvm_iodevice_init(&pit->dev, &pit_dev_ops); ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS, @@ -712,8 +732,7 @@ fail_unregister: kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev); fail: - kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier); - kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier); + kvm_pit_set_reinject(pit, false); kvm_free_irq_source_id(kvm, pit->irq_source_id); kthread_stop(pit->worker_task); kfree(pit); @@ -728,10 +747,7 @@ void kvm_free_pit(struct kvm *kvm) kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->dev); kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &kvm->arch.vpit->speaker_dev); - kvm_unregister_irq_mask_notifier(kvm, 0, - &kvm->arch.vpit->mask_notifier); - kvm_unregister_irq_ack_notifier(kvm, - &kvm->arch.vpit->pit_state.irq_ack_notifier); + kvm_pit_set_reinject(kvm->arch.vpit, false); timer = &kvm->arch.vpit->pit_state.timer; hrtimer_cancel(timer); flush_kthread_work(&kvm->arch.vpit->expired); -- cgit v1.2.3