diff options
Diffstat (limited to 'virt/kvm/eventfd.c')
| -rw-r--r-- | virt/kvm/eventfd.c | 150 |
1 files changed, 146 insertions, 4 deletions
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 7d7e2aa..356965c 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -43,6 +43,31 @@ * -------------------------------------------------------------------- */ +/* + * Resampling irqfds are a special variety of irqfds used to emulate + * level triggered interrupts. The interrupt is asserted on eventfd + * trigger. On acknowledgement through the irq ack notifier, the + * interrupt is de-asserted and userspace is notified through the + * resamplefd. All resamplers on the same gsi are de-asserted + * together, so we don't need to track the state of each individual + * user. We can also therefore share the same irq source ID. + */ +struct _irqfd_resampler { + struct kvm *kvm; + /* + * List of resampling struct _irqfd objects sharing this gsi. + * RCU list modified under kvm->irqfds.resampler_lock + */ + struct list_head list; + struct kvm_irq_ack_notifier notifier; + /* + * Entry in list of kvm->irqfd.resampler_list. Use for sharing + * resamplers among irqfds on the same gsi. + * Accessed and modified under kvm->irqfds.resampler_lock + */ + struct list_head link; +}; + struct _irqfd { /* Used for MSI fast-path */ struct kvm *kvm; @@ -52,6 +77,12 @@ struct _irqfd { /* Used for level IRQ fast-path */ int gsi; struct work_struct inject; + /* The resampler used by this irqfd (resampler-only) */ + struct _irqfd_resampler *resampler; + /* Eventfd notified on resample (resampler-only) */ + struct eventfd_ctx *resamplefd; + /* Entry in list of irqfds for a resampler (resampler-only) */ + struct list_head resampler_link; /* Used for setup/shutdown */ struct eventfd_ctx *eventfd; struct list_head list; @@ -67,8 +98,58 @@ irqfd_inject(struct work_struct *work) struct _irqfd *irqfd = container_of(work, struct _irqfd, inject); struct kvm *kvm = irqfd->kvm; - kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1); - kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0); + if (!irqfd->resampler) { + kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1); + kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0); + } else + kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + irqfd->gsi, 1); +} + +/* + * Since resampler irqfds share an IRQ source ID, we de-assert once + * then notify all of the resampler irqfds using this GSI. We can't + * do multiple de-asserts or we risk racing with incoming re-asserts. + */ +static void +irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian) +{ + struct _irqfd_resampler *resampler; + struct _irqfd *irqfd; + + resampler = container_of(kian, struct _irqfd_resampler, notifier); + + kvm_set_irq(resampler->kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + resampler->notifier.gsi, 0); + + rcu_read_lock(); + + list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link) + eventfd_signal(irqfd->resamplefd, 1); + + rcu_read_unlock(); +} + +static void +irqfd_resampler_shutdown(struct _irqfd *irqfd) +{ + struct _irqfd_resampler *resampler = irqfd->resampler; + struct kvm *kvm = resampler->kvm; + + mutex_lock(&kvm->irqfds.resampler_lock); + + list_del_rcu(&irqfd->resampler_link); + synchronize_rcu(); + + if (list_empty(&resampler->list)) { + list_del(&resampler->link); + kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier); + kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + resampler->notifier.gsi, 0); + kfree(resampler); + } + + mutex_unlock(&kvm->irqfds.resampler_lock); } /* @@ -92,6 +173,11 @@ irqfd_shutdown(struct work_struct *work) */ flush_work_sync(&irqfd->inject); + if (irqfd->resampler) { + irqfd_resampler_shutdown(irqfd); + eventfd_ctx_put(irqfd->resamplefd); + } + /* * It is now safe to release the object's resources */ @@ -203,7 +289,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) struct kvm_irq_routing_table *irq_rt; struct _irqfd *irqfd, *tmp; struct file *file = NULL; - struct eventfd_ctx *eventfd = NULL; + struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL; int ret; unsigned int events; @@ -231,6 +317,54 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) irqfd->eventfd = eventfd; + if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) { + struct _irqfd_resampler *resampler; + + resamplefd = eventfd_ctx_fdget(args->resamplefd); + if (IS_ERR(resamplefd)) { + ret = PTR_ERR(resamplefd); + goto fail; + } + + irqfd->resamplefd = resamplefd; + INIT_LIST_HEAD(&irqfd->resampler_link); + + mutex_lock(&kvm->irqfds.resampler_lock); + + list_for_each_entry(resampler, + &kvm->irqfds.resampler_list, list) { + if (resampler->notifier.gsi == irqfd->gsi) { + irqfd->resampler = resampler; + break; + } + } + + if (!irqfd->resampler) { + resampler = kzalloc(sizeof(*resampler), GFP_KERNEL); + if (!resampler) { + ret = -ENOMEM; + mutex_unlock(&kvm->irqfds.resampler_lock); + goto fail; + } + + resampler->kvm = kvm; + INIT_LIST_HEAD(&resampler->list); + resampler->notifier.gsi = irqfd->gsi; + resampler->notifier.irq_acked = irqfd_resampler_ack; + INIT_LIST_HEAD(&resampler->link); + + list_add(&resampler->link, &kvm->irqfds.resampler_list); + kvm_register_irq_ack_notifier(kvm, + &resampler->notifier); + irqfd->resampler = resampler; + } + + list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list); + synchronize_rcu(); + + mutex_unlock(&kvm->irqfds.resampler_lock); + } + /* * Install our own custom wake-up handling so we are notified via * a callback whenever someone signals the underlying eventfd @@ -276,6 +410,12 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) return 0; fail: + if (irqfd->resampler) + irqfd_resampler_shutdown(irqfd); + + if (resamplefd && !IS_ERR(resamplefd)) + eventfd_ctx_put(resamplefd); + if (eventfd && !IS_ERR(eventfd)) eventfd_ctx_put(eventfd); @@ -291,6 +431,8 @@ kvm_eventfd_init(struct kvm *kvm) { spin_lock_init(&kvm->irqfds.lock); INIT_LIST_HEAD(&kvm->irqfds.items); + INIT_LIST_HEAD(&kvm->irqfds.resampler_list); + mutex_init(&kvm->irqfds.resampler_lock); INIT_LIST_HEAD(&kvm->ioeventfds); } @@ -340,7 +482,7 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args) int kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args) { - if (args->flags & ~KVM_IRQFD_FLAG_DEASSIGN) + if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE)) return -EINVAL; if (args->flags & KVM_IRQFD_FLAG_DEASSIGN) |
