2 * kvm eventfd support - use eventfd objects to signal various KVM events
4 * Copyright 2009 Novell. All Rights Reserved.
5 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
8 * Gregory Haskins <ghaskins@novell.com>
10 * This file is free software; you can redistribute it and/or modify
11 * it under the terms of version 2 of the GNU General Public License
12 * as published by the Free Software Foundation.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
24 #include <linux/kvm_host.h>
25 #include <linux/kvm.h>
26 #include <linux/workqueue.h>
27 #include <linux/syscalls.h>
28 #include <linux/wait.h>
29 #include <linux/poll.h>
30 #include <linux/file.h>
31 #include <linux/list.h>
32 #include <linux/eventfd.h>
33 #include <linux/kernel.h>
34 #include <linux/srcu.h>
35 #include <linux/slab.h>
36 #include <linux/seqlock.h>
37 #include <trace/events/kvm.h>
41 #ifdef CONFIG_HAVE_KVM_IRQFD
43 * --------------------------------------------------------------------
44 * irqfd: Allows an fd to be used to inject an interrupt to the guest
46 * Credit goes to Avi Kivity for the original idea.
47 * --------------------------------------------------------------------
51 * Resampling irqfds are a special variety of irqfds used to emulate
52 * level triggered interrupts. The interrupt is asserted on eventfd
53 * trigger. On acknowledgement through the irq ack notifier, the
54 * interrupt is de-asserted and userspace is notified through the
55 * resamplefd. All resamplers on the same gsi are de-asserted
56 * together, so we don't need to track the state of each individual
57 * user. We can also therefore share the same irq source ID.
59 struct _irqfd_resampler {
62 * List of resampling struct _irqfd objects sharing this gsi.
63 * RCU list modified under kvm->irqfds.resampler_lock
65 struct list_head list;
66 struct kvm_irq_ack_notifier notifier;
68 * Entry in list of kvm->irqfd.resampler_list. Use for sharing
69 * resamplers among irqfds on the same gsi.
70 * Accessed and modified under kvm->irqfds.resampler_lock
72 struct list_head link;
76 /* Used for MSI fast-path */
79 /* Update side is protected by irqfds.lock */
80 struct kvm_kernel_irq_routing_entry irq_entry;
81 seqcount_t irq_entry_sc;
82 /* Used for level IRQ fast-path */
84 struct work_struct inject;
85 /* The resampler used by this irqfd (resampler-only) */
86 struct _irqfd_resampler *resampler;
87 /* Eventfd notified on resample (resampler-only) */
88 struct eventfd_ctx *resamplefd;
89 /* Entry in list of irqfds for a resampler (resampler-only) */
90 struct list_head resampler_link;
91 /* Used for setup/shutdown */
92 struct eventfd_ctx *eventfd;
93 struct list_head list;
95 struct work_struct shutdown;
98 static struct workqueue_struct *irqfd_cleanup_wq;
101 irqfd_inject(struct work_struct *work)
103 struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
104 struct kvm *kvm = irqfd->kvm;
106 if (!irqfd->resampler) {
107 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
109 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
112 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
113 irqfd->gsi, 1, false);
117 * Since resampler irqfds share an IRQ source ID, we de-assert once
118 * then notify all of the resampler irqfds using this GSI. We can't
119 * do multiple de-asserts or we risk racing with incoming re-asserts.
122 irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
124 struct _irqfd_resampler *resampler;
126 struct _irqfd *irqfd;
129 resampler = container_of(kian, struct _irqfd_resampler, notifier);
130 kvm = resampler->kvm;
132 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
133 resampler->notifier.gsi, 0, false);
135 idx = srcu_read_lock(&kvm->irq_srcu);
137 list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link)
138 eventfd_signal(irqfd->resamplefd, 1);
140 srcu_read_unlock(&kvm->irq_srcu, idx);
144 irqfd_resampler_shutdown(struct _irqfd *irqfd)
146 struct _irqfd_resampler *resampler = irqfd->resampler;
147 struct kvm *kvm = resampler->kvm;
149 mutex_lock(&kvm->irqfds.resampler_lock);
151 list_del_rcu(&irqfd->resampler_link);
152 synchronize_srcu(&kvm->irq_srcu);
154 if (list_empty(&resampler->list)) {
155 list_del(&resampler->link);
156 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
157 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
158 resampler->notifier.gsi, 0, false);
162 mutex_unlock(&kvm->irqfds.resampler_lock);
166 * Race-free decouple logic (ordering is critical)
169 irqfd_shutdown(struct work_struct *work)
171 struct _irqfd *irqfd = container_of(work, struct _irqfd, shutdown);
175 * Synchronize with the wait-queue and unhook ourselves to prevent
178 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
181 * We know no new events will be scheduled at this point, so block
182 * until all previously outstanding events have completed
184 flush_work(&irqfd->inject);
186 if (irqfd->resampler) {
187 irqfd_resampler_shutdown(irqfd);
188 eventfd_ctx_put(irqfd->resamplefd);
192 * It is now safe to release the object's resources
194 eventfd_ctx_put(irqfd->eventfd);
199 /* assumes kvm->irqfds.lock is held */
201 irqfd_is_active(struct _irqfd *irqfd)
203 return list_empty(&irqfd->list) ? false : true;
207 * Mark the irqfd as inactive and schedule it for removal
209 * assumes kvm->irqfds.lock is held
212 irqfd_deactivate(struct _irqfd *irqfd)
214 BUG_ON(!irqfd_is_active(irqfd));
216 list_del_init(&irqfd->list);
218 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
222 * Called with wqh->lock held and interrupts disabled
225 irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
227 struct _irqfd *irqfd = container_of(wait, struct _irqfd, wait);
228 unsigned long flags = (unsigned long)key;
229 struct kvm_kernel_irq_routing_entry irq;
230 struct kvm *kvm = irqfd->kvm;
234 if (flags & POLLIN) {
235 idx = srcu_read_lock(&kvm->irq_srcu);
237 seq = read_seqcount_begin(&irqfd->irq_entry_sc);
238 irq = irqfd->irq_entry;
239 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
240 /* An event has been signaled, inject an interrupt */
241 if (irq.type == KVM_IRQ_ROUTING_MSI)
242 kvm_set_msi(&irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1,
245 schedule_work(&irqfd->inject);
246 srcu_read_unlock(&kvm->irq_srcu, idx);
249 if (flags & POLLHUP) {
250 /* The eventfd is closing, detach from KVM */
253 spin_lock_irqsave(&kvm->irqfds.lock, flags);
256 * We must check if someone deactivated the irqfd before
257 * we could acquire the irqfds.lock since the item is
258 * deactivated from the KVM side before it is unhooked from
259 * the wait-queue. If it is already deactivated, we can
260 * simply return knowing the other side will cleanup for us.
261 * We cannot race against the irqfd going away since the
262 * other side is required to acquire wqh->lock, which we hold
264 if (irqfd_is_active(irqfd))
265 irqfd_deactivate(irqfd);
267 spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
274 irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
277 struct _irqfd *irqfd = container_of(pt, struct _irqfd, pt);
278 add_wait_queue(wqh, &irqfd->wait);
281 /* Must be called under irqfds.lock */
282 static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd)
284 struct kvm_kernel_irq_routing_entry *e;
285 struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
288 n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
290 write_seqcount_begin(&irqfd->irq_entry_sc);
292 irqfd->irq_entry.type = 0;
295 for (i = 0; i < n_entries; ++i, ++e) {
296 /* Only fast-path MSI. */
297 if (e->type == KVM_IRQ_ROUTING_MSI)
298 irqfd->irq_entry = *e;
301 write_seqcount_end(&irqfd->irq_entry_sc);
305 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
307 struct _irqfd *irqfd, *tmp;
309 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
314 if (!kvm_arch_intc_initialized(kvm))
317 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
322 irqfd->gsi = args->gsi;
323 INIT_LIST_HEAD(&irqfd->list);
324 INIT_WORK(&irqfd->inject, irqfd_inject);
325 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
326 seqcount_init(&irqfd->irq_entry_sc);
334 eventfd = eventfd_ctx_fileget(f.file);
335 if (IS_ERR(eventfd)) {
336 ret = PTR_ERR(eventfd);
340 irqfd->eventfd = eventfd;
342 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
343 struct _irqfd_resampler *resampler;
345 resamplefd = eventfd_ctx_fdget(args->resamplefd);
346 if (IS_ERR(resamplefd)) {
347 ret = PTR_ERR(resamplefd);
351 irqfd->resamplefd = resamplefd;
352 INIT_LIST_HEAD(&irqfd->resampler_link);
354 mutex_lock(&kvm->irqfds.resampler_lock);
356 list_for_each_entry(resampler,
357 &kvm->irqfds.resampler_list, link) {
358 if (resampler->notifier.gsi == irqfd->gsi) {
359 irqfd->resampler = resampler;
364 if (!irqfd->resampler) {
365 resampler = kzalloc(sizeof(*resampler), GFP_KERNEL);
368 mutex_unlock(&kvm->irqfds.resampler_lock);
372 resampler->kvm = kvm;
373 INIT_LIST_HEAD(&resampler->list);
374 resampler->notifier.gsi = irqfd->gsi;
375 resampler->notifier.irq_acked = irqfd_resampler_ack;
376 INIT_LIST_HEAD(&resampler->link);
378 list_add(&resampler->link, &kvm->irqfds.resampler_list);
379 kvm_register_irq_ack_notifier(kvm,
380 &resampler->notifier);
381 irqfd->resampler = resampler;
384 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
385 synchronize_srcu(&kvm->irq_srcu);
387 mutex_unlock(&kvm->irqfds.resampler_lock);
391 * Install our own custom wake-up handling so we are notified via
392 * a callback whenever someone signals the underlying eventfd
394 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
395 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
397 spin_lock_irq(&kvm->irqfds.lock);
400 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
401 if (irqfd->eventfd != tmp->eventfd)
403 /* This fd is used for another irq already. */
405 spin_unlock_irq(&kvm->irqfds.lock);
409 idx = srcu_read_lock(&kvm->irq_srcu);
410 irqfd_update(kvm, irqfd);
411 srcu_read_unlock(&kvm->irq_srcu, idx);
413 list_add_tail(&irqfd->list, &kvm->irqfds.items);
415 spin_unlock_irq(&kvm->irqfds.lock);
418 * Check if there was an event already pending on the eventfd
419 * before we registered, and trigger it as if we didn't miss it.
421 events = f.file->f_op->poll(f.file, &irqfd->pt);
424 schedule_work(&irqfd->inject);
427 * do not drop the file until the irqfd is fully initialized, otherwise
428 * we might race against the POLLHUP
435 if (irqfd->resampler)
436 irqfd_resampler_shutdown(irqfd);
438 if (resamplefd && !IS_ERR(resamplefd))
439 eventfd_ctx_put(resamplefd);
441 if (eventfd && !IS_ERR(eventfd))
442 eventfd_ctx_put(eventfd);
451 bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
453 struct kvm_irq_ack_notifier *kian;
456 idx = srcu_read_lock(&kvm->irq_srcu);
457 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
459 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
461 if (kian->gsi == gsi) {
462 srcu_read_unlock(&kvm->irq_srcu, idx);
466 srcu_read_unlock(&kvm->irq_srcu, idx);
470 EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
472 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
474 struct kvm_irq_ack_notifier *kian;
477 trace_kvm_ack_irq(irqchip, pin);
479 idx = srcu_read_lock(&kvm->irq_srcu);
480 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
482 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
484 if (kian->gsi == gsi)
485 kian->irq_acked(kian);
486 srcu_read_unlock(&kvm->irq_srcu, idx);
489 void kvm_register_irq_ack_notifier(struct kvm *kvm,
490 struct kvm_irq_ack_notifier *kian)
492 mutex_lock(&kvm->irq_lock);
493 hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
494 mutex_unlock(&kvm->irq_lock);
495 kvm_vcpu_request_scan_ioapic(kvm);
498 void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
499 struct kvm_irq_ack_notifier *kian)
501 mutex_lock(&kvm->irq_lock);
502 hlist_del_init_rcu(&kian->link);
503 mutex_unlock(&kvm->irq_lock);
504 synchronize_srcu(&kvm->irq_srcu);
505 kvm_vcpu_request_scan_ioapic(kvm);
510 kvm_eventfd_init(struct kvm *kvm)
512 #ifdef CONFIG_HAVE_KVM_IRQFD
513 spin_lock_init(&kvm->irqfds.lock);
514 INIT_LIST_HEAD(&kvm->irqfds.items);
515 INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
516 mutex_init(&kvm->irqfds.resampler_lock);
518 INIT_LIST_HEAD(&kvm->ioeventfds);
521 #ifdef CONFIG_HAVE_KVM_IRQFD
523 * shutdown any irqfd's that match fd+gsi
526 kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
528 struct _irqfd *irqfd, *tmp;
529 struct eventfd_ctx *eventfd;
531 eventfd = eventfd_ctx_fdget(args->fd);
533 return PTR_ERR(eventfd);
535 spin_lock_irq(&kvm->irqfds.lock);
537 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
538 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
540 * This clearing of irq_entry.type is needed for when
541 * another thread calls kvm_irq_routing_update before
542 * we flush workqueue below (we synchronize with
543 * kvm_irq_routing_update using irqfds.lock).
545 write_seqcount_begin(&irqfd->irq_entry_sc);
546 irqfd->irq_entry.type = 0;
547 write_seqcount_end(&irqfd->irq_entry_sc);
548 irqfd_deactivate(irqfd);
552 spin_unlock_irq(&kvm->irqfds.lock);
553 eventfd_ctx_put(eventfd);
556 * Block until we know all outstanding shutdown jobs have completed
557 * so that we guarantee there will not be any more interrupts on this
558 * gsi once this deassign function returns.
560 flush_workqueue(irqfd_cleanup_wq);
566 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
568 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
571 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
572 return kvm_irqfd_deassign(kvm, args);
574 return kvm_irqfd_assign(kvm, args);
578 * This function is called as the kvm VM fd is being released. Shutdown all
579 * irqfds that still remain open
582 kvm_irqfd_release(struct kvm *kvm)
584 struct _irqfd *irqfd, *tmp;
586 spin_lock_irq(&kvm->irqfds.lock);
588 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
589 irqfd_deactivate(irqfd);
591 spin_unlock_irq(&kvm->irqfds.lock);
594 * Block until we know all outstanding shutdown jobs have completed
595 * since we do not take a kvm* reference.
597 flush_workqueue(irqfd_cleanup_wq);
602 * Take note of a change in irq routing.
603 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
605 void kvm_irq_routing_update(struct kvm *kvm)
607 struct _irqfd *irqfd;
609 spin_lock_irq(&kvm->irqfds.lock);
611 list_for_each_entry(irqfd, &kvm->irqfds.items, list)
612 irqfd_update(kvm, irqfd);
614 spin_unlock_irq(&kvm->irqfds.lock);
618 * create a host-wide workqueue for issuing deferred shutdown requests
619 * aggregated from all vm* instances. We need our own isolated single-thread
620 * queue to prevent deadlock against flushing the normal work-queue.
622 int kvm_irqfd_init(void)
624 irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
625 if (!irqfd_cleanup_wq)
631 void kvm_irqfd_exit(void)
633 destroy_workqueue(irqfd_cleanup_wq);
638 * --------------------------------------------------------------------
639 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
641 * userspace can register a PIO/MMIO address with an eventfd for receiving
642 * notification when the memory has been touched.
643 * --------------------------------------------------------------------
647 struct list_head list;
650 struct eventfd_ctx *eventfd;
652 struct kvm_io_device dev;
657 static inline struct _ioeventfd *
658 to_ioeventfd(struct kvm_io_device *dev)
660 return container_of(dev, struct _ioeventfd, dev);
664 ioeventfd_release(struct _ioeventfd *p)
666 eventfd_ctx_put(p->eventfd);
672 ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
677 /* address must be precise for a hit */
681 /* length = 0 means only look at the address, so always a hit */
684 if (len != p->length)
685 /* address-range must be precise for a hit */
689 /* all else equal, wildcard is always a hit */
692 /* otherwise, we have to actually compare the data */
694 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
713 return _val == p->datamatch ? true : false;
716 /* MMIO/PIO writes trigger an event if the addr/val match */
718 ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
719 int len, const void *val)
721 struct _ioeventfd *p = to_ioeventfd(this);
723 if (!ioeventfd_in_range(p, addr, len, val))
726 eventfd_signal(p->eventfd, 1);
731 * This function is called as KVM is completely shutting down. We do not
732 * need to worry about locking just nuke anything we have as quickly as possible
735 ioeventfd_destructor(struct kvm_io_device *this)
737 struct _ioeventfd *p = to_ioeventfd(this);
739 ioeventfd_release(p);
742 static const struct kvm_io_device_ops ioeventfd_ops = {
743 .write = ioeventfd_write,
744 .destructor = ioeventfd_destructor,
747 /* assumes kvm->slots_lock held */
749 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
751 struct _ioeventfd *_p;
753 list_for_each_entry(_p, &kvm->ioeventfds, list)
754 if (_p->bus_idx == p->bus_idx &&
755 _p->addr == p->addr &&
756 (!_p->length || !p->length ||
757 (_p->length == p->length &&
758 (_p->wildcard || p->wildcard ||
759 _p->datamatch == p->datamatch))))
765 static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
767 if (flags & KVM_IOEVENTFD_FLAG_PIO)
769 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
770 return KVM_VIRTIO_CCW_NOTIFY_BUS;
775 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
777 enum kvm_bus bus_idx;
778 struct _ioeventfd *p;
779 struct eventfd_ctx *eventfd;
782 bus_idx = ioeventfd_bus_from_flags(args->flags);
783 /* must be natural-word sized, or 0 to ignore length */
795 /* check for range overflow */
796 if (args->addr + args->len < args->addr)
799 /* check for extra flags that we don't understand */
800 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
803 /* ioeventfd with no length can't be combined with DATAMATCH */
805 args->flags & (KVM_IOEVENTFD_FLAG_PIO |
806 KVM_IOEVENTFD_FLAG_DATAMATCH))
809 eventfd = eventfd_ctx_fdget(args->fd);
811 return PTR_ERR(eventfd);
813 p = kzalloc(sizeof(*p), GFP_KERNEL);
819 INIT_LIST_HEAD(&p->list);
820 p->addr = args->addr;
821 p->bus_idx = bus_idx;
822 p->length = args->len;
823 p->eventfd = eventfd;
825 /* The datamatch feature is optional, otherwise this is a wildcard */
826 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
827 p->datamatch = args->datamatch;
831 mutex_lock(&kvm->slots_lock);
833 /* Verify that there isn't a match already */
834 if (ioeventfd_check_collision(kvm, p)) {
839 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
841 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
846 /* When length is ignored, MMIO is also put on a separate bus, for
849 if (!args->len && !(args->flags & KVM_IOEVENTFD_FLAG_PIO)) {
850 ret = kvm_io_bus_register_dev(kvm, KVM_FAST_MMIO_BUS,
851 p->addr, 0, &p->dev);
856 kvm->buses[bus_idx]->ioeventfd_count++;
857 list_add_tail(&p->list, &kvm->ioeventfds);
859 mutex_unlock(&kvm->slots_lock);
864 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
866 mutex_unlock(&kvm->slots_lock);
870 eventfd_ctx_put(eventfd);
876 kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
878 enum kvm_bus bus_idx;
879 struct _ioeventfd *p, *tmp;
880 struct eventfd_ctx *eventfd;
883 bus_idx = ioeventfd_bus_from_flags(args->flags);
884 eventfd = eventfd_ctx_fdget(args->fd);
886 return PTR_ERR(eventfd);
888 mutex_lock(&kvm->slots_lock);
890 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
891 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
893 if (p->bus_idx != bus_idx ||
894 p->eventfd != eventfd ||
895 p->addr != args->addr ||
896 p->length != args->len ||
897 p->wildcard != wildcard)
900 if (!p->wildcard && p->datamatch != args->datamatch)
903 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
905 kvm_io_bus_unregister_dev(kvm, KVM_FAST_MMIO_BUS,
908 kvm->buses[bus_idx]->ioeventfd_count--;
909 ioeventfd_release(p);
914 mutex_unlock(&kvm->slots_lock);
916 eventfd_ctx_put(eventfd);
922 kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
924 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
925 return kvm_deassign_ioeventfd(kvm, args);
927 return kvm_assign_ioeventfd(kvm, args);