From 71474e2f0f439b83b7b53ee6e9cf4f44c15b5806 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Date: Wed, 2 Mar 2016 22:56:45 +0100 Subject: [PATCH] KVM: i8254: remove notifiers from PIT discard policy MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 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 +++++++++++++++++++++++++++----------- arch/x86/kvm/i8254.h | 1 + arch/x86/kvm/x86.c | 12 ++++++++++-- 3 files changed, 38 insertions(+), 13 deletions(-) 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); diff --git a/arch/x86/kvm/i8254.h b/arch/x86/kvm/i8254.h index 840fbb3cb626..1945635904a7 100644 --- a/arch/x86/kvm/i8254.h +++ b/arch/x86/kvm/i8254.h @@ -63,5 +63,6 @@ void kvm_free_pit(struct kvm *kvm); void kvm_pit_load_count(struct kvm_pit *pit, int channel, u32 val, int hpet_legacy_start); +void kvm_pit_set_reinject(struct kvm_pit *pit, bool reinject); #endif diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ce4e91db5bae..76f9f48898a5 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3659,10 +3659,18 @@ static int kvm_vm_ioctl_set_pit2(struct kvm *kvm, struct kvm_pit_state2 *ps) static int kvm_vm_ioctl_reinject(struct kvm *kvm, struct kvm_reinject_control *control) { - if (!kvm->arch.vpit) + struct kvm_pit *pit = kvm->arch.vpit; + + if (!pit) return -ENXIO; - kvm->arch.vpit->pit_state.reinject = control->pit_reinject; + /* pit->pit_state.lock was overloaded to prevent userspace from getting + * an inconsistent state after running multiple KVM_REINJECT_CONTROL + * ioctls in parallel. Use a separate lock if that ioctl isn't rare. + */ + mutex_lock(&pit->pit_state.lock); + kvm_pit_set_reinject(pit, control->pit_reinject); + mutex_unlock(&pit->pit_state.lock); return 0; } -- 2.20.1