* --------------------------------------------------------------------
*/
+/*
+ * 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;
/* 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;
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);
}
/*
*/
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
*/
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;
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
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);
{
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);
}
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)
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