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/kvm_irqfd.h>
27 #include <linux/workqueue.h>
28 #include <linux/syscalls.h>
29 #include <linux/wait.h>
30 #include <linux/poll.h>
31 #include <linux/file.h>
32 #include <linux/list.h>
33 #include <linux/eventfd.h>
34 #include <linux/kernel.h>
35 #include <linux/srcu.h>
36 #include <linux/slab.h>
37 #include <linux/seqlock.h>
38 #include <linux/irqbypass.h>
39 #include <trace/events/kvm.h>
41 #include <kvm/iodev.h>
43 #ifdef CONFIG_HAVE_KVM_IRQFD
45 static struct workqueue_struct *irqfd_cleanup_wq;
47 bool __attribute__((weak))
48 kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
54 irqfd_inject(struct work_struct *work)
56 struct kvm_kernel_irqfd *irqfd =
57 container_of(work, struct kvm_kernel_irqfd, inject);
58 struct kvm *kvm = irqfd->kvm;
60 if (!irqfd->resampler) {
61 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
63 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
66 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
67 irqfd->gsi, 1, false);
71 * Since resampler irqfds share an IRQ source ID, we de-assert once
72 * then notify all of the resampler irqfds using this GSI. We can't
73 * do multiple de-asserts or we risk racing with incoming re-asserts.
76 irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
78 struct kvm_kernel_irqfd_resampler *resampler;
80 struct kvm_kernel_irqfd *irqfd;
83 resampler = container_of(kian,
84 struct kvm_kernel_irqfd_resampler, notifier);
87 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
88 resampler->notifier.gsi, 0, false);
90 idx = srcu_read_lock(&kvm->irq_srcu);
92 list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link)
93 eventfd_signal(irqfd->resamplefd, 1);
95 srcu_read_unlock(&kvm->irq_srcu, idx);
99 irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
101 struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
102 struct kvm *kvm = resampler->kvm;
104 mutex_lock(&kvm->irqfds.resampler_lock);
106 list_del_rcu(&irqfd->resampler_link);
107 synchronize_srcu(&kvm->irq_srcu);
109 if (list_empty(&resampler->list)) {
110 list_del(&resampler->link);
111 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
112 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
113 resampler->notifier.gsi, 0, false);
117 mutex_unlock(&kvm->irqfds.resampler_lock);
121 * Race-free decouple logic (ordering is critical)
124 irqfd_shutdown(struct work_struct *work)
126 struct kvm_kernel_irqfd *irqfd =
127 container_of(work, struct kvm_kernel_irqfd, shutdown);
128 struct kvm *kvm = irqfd->kvm;
131 /* Make sure irqfd has been initalized in assign path. */
132 synchronize_srcu(&kvm->irq_srcu);
135 * Synchronize with the wait-queue and unhook ourselves to prevent
138 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
141 * We know no new events will be scheduled at this point, so block
142 * until all previously outstanding events have completed
144 flush_work(&irqfd->inject);
146 if (irqfd->resampler) {
147 irqfd_resampler_shutdown(irqfd);
148 eventfd_ctx_put(irqfd->resamplefd);
152 * It is now safe to release the object's resources
154 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
155 irq_bypass_unregister_consumer(&irqfd->consumer);
157 eventfd_ctx_put(irqfd->eventfd);
162 /* assumes kvm->irqfds.lock is held */
164 irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
166 return list_empty(&irqfd->list) ? false : true;
170 * Mark the irqfd as inactive and schedule it for removal
172 * assumes kvm->irqfds.lock is held
175 irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
177 BUG_ON(!irqfd_is_active(irqfd));
179 list_del_init(&irqfd->list);
181 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
184 int __attribute__((weak)) kvm_arch_set_irq_inatomic(
185 struct kvm_kernel_irq_routing_entry *irq,
186 struct kvm *kvm, int irq_source_id,
194 * Called with wqh->lock held and interrupts disabled
197 irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
199 struct kvm_kernel_irqfd *irqfd =
200 container_of(wait, struct kvm_kernel_irqfd, wait);
201 __poll_t flags = key_to_poll(key);
202 struct kvm_kernel_irq_routing_entry irq;
203 struct kvm *kvm = irqfd->kvm;
207 if (flags & EPOLLIN) {
208 idx = srcu_read_lock(&kvm->irq_srcu);
210 seq = read_seqcount_begin(&irqfd->irq_entry_sc);
211 irq = irqfd->irq_entry;
212 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
213 /* An event has been signaled, inject an interrupt */
214 if (kvm_arch_set_irq_inatomic(&irq, kvm,
215 KVM_USERSPACE_IRQ_SOURCE_ID, 1,
216 false) == -EWOULDBLOCK)
217 schedule_work(&irqfd->inject);
218 srcu_read_unlock(&kvm->irq_srcu, idx);
221 if (flags & EPOLLHUP) {
222 /* The eventfd is closing, detach from KVM */
223 unsigned long iflags;
225 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
228 * We must check if someone deactivated the irqfd before
229 * we could acquire the irqfds.lock since the item is
230 * deactivated from the KVM side before it is unhooked from
231 * the wait-queue. If it is already deactivated, we can
232 * simply return knowing the other side will cleanup for us.
233 * We cannot race against the irqfd going away since the
234 * other side is required to acquire wqh->lock, which we hold
236 if (irqfd_is_active(irqfd))
237 irqfd_deactivate(irqfd);
239 spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
246 irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
249 struct kvm_kernel_irqfd *irqfd =
250 container_of(pt, struct kvm_kernel_irqfd, pt);
251 add_wait_queue(wqh, &irqfd->wait);
254 /* Must be called under irqfds.lock */
255 static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
257 struct kvm_kernel_irq_routing_entry *e;
258 struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
261 n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
263 write_seqcount_begin(&irqfd->irq_entry_sc);
267 irqfd->irq_entry = *e;
269 irqfd->irq_entry.type = 0;
271 write_seqcount_end(&irqfd->irq_entry_sc);
274 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
275 void __attribute__((weak)) kvm_arch_irq_bypass_stop(
276 struct irq_bypass_consumer *cons)
280 void __attribute__((weak)) kvm_arch_irq_bypass_start(
281 struct irq_bypass_consumer *cons)
285 int __attribute__((weak)) kvm_arch_update_irqfd_routing(
286 struct kvm *kvm, unsigned int host_irq,
287 uint32_t guest_irq, bool set)
294 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
296 struct kvm_kernel_irqfd *irqfd, *tmp;
298 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
303 if (!kvm_arch_intc_initialized(kvm))
306 if (!kvm_arch_irqfd_allowed(kvm, args))
309 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
314 irqfd->gsi = args->gsi;
315 INIT_LIST_HEAD(&irqfd->list);
316 INIT_WORK(&irqfd->inject, irqfd_inject);
317 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
318 seqcount_init(&irqfd->irq_entry_sc);
326 eventfd = eventfd_ctx_fileget(f.file);
327 if (IS_ERR(eventfd)) {
328 ret = PTR_ERR(eventfd);
332 irqfd->eventfd = eventfd;
334 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
335 struct kvm_kernel_irqfd_resampler *resampler;
337 resamplefd = eventfd_ctx_fdget(args->resamplefd);
338 if (IS_ERR(resamplefd)) {
339 ret = PTR_ERR(resamplefd);
343 irqfd->resamplefd = resamplefd;
344 INIT_LIST_HEAD(&irqfd->resampler_link);
346 mutex_lock(&kvm->irqfds.resampler_lock);
348 list_for_each_entry(resampler,
349 &kvm->irqfds.resampler_list, link) {
350 if (resampler->notifier.gsi == irqfd->gsi) {
351 irqfd->resampler = resampler;
356 if (!irqfd->resampler) {
357 resampler = kzalloc(sizeof(*resampler),
361 mutex_unlock(&kvm->irqfds.resampler_lock);
365 resampler->kvm = kvm;
366 INIT_LIST_HEAD(&resampler->list);
367 resampler->notifier.gsi = irqfd->gsi;
368 resampler->notifier.irq_acked = irqfd_resampler_ack;
369 INIT_LIST_HEAD(&resampler->link);
371 list_add(&resampler->link, &kvm->irqfds.resampler_list);
372 kvm_register_irq_ack_notifier(kvm,
373 &resampler->notifier);
374 irqfd->resampler = resampler;
377 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
378 synchronize_srcu(&kvm->irq_srcu);
380 mutex_unlock(&kvm->irqfds.resampler_lock);
384 * Install our own custom wake-up handling so we are notified via
385 * a callback whenever someone signals the underlying eventfd
387 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
388 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
390 spin_lock_irq(&kvm->irqfds.lock);
393 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
394 if (irqfd->eventfd != tmp->eventfd)
396 /* This fd is used for another irq already. */
398 spin_unlock_irq(&kvm->irqfds.lock);
402 idx = srcu_read_lock(&kvm->irq_srcu);
403 irqfd_update(kvm, irqfd);
405 list_add_tail(&irqfd->list, &kvm->irqfds.items);
407 spin_unlock_irq(&kvm->irqfds.lock);
410 * Check if there was an event already pending on the eventfd
411 * before we registered, and trigger it as if we didn't miss it.
413 events = vfs_poll(f.file, &irqfd->pt);
415 if (events & EPOLLIN)
416 schedule_work(&irqfd->inject);
418 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
419 if (kvm_arch_has_irq_bypass()) {
420 irqfd->consumer.token = (void *)irqfd->eventfd;
421 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
422 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
423 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
424 irqfd->consumer.start = kvm_arch_irq_bypass_start;
425 ret = irq_bypass_register_consumer(&irqfd->consumer);
427 pr_info("irq bypass consumer (token %p) registration fails: %d\n",
428 irqfd->consumer.token, ret);
432 srcu_read_unlock(&kvm->irq_srcu, idx);
435 * do not drop the file until the irqfd is fully initialized, otherwise
436 * we might race against the EPOLLHUP
442 if (irqfd->resampler)
443 irqfd_resampler_shutdown(irqfd);
445 if (resamplefd && !IS_ERR(resamplefd))
446 eventfd_ctx_put(resamplefd);
448 if (eventfd && !IS_ERR(eventfd))
449 eventfd_ctx_put(eventfd);
458 bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
460 struct kvm_irq_ack_notifier *kian;
463 idx = srcu_read_lock(&kvm->irq_srcu);
464 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
466 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
468 if (kian->gsi == gsi) {
469 srcu_read_unlock(&kvm->irq_srcu, idx);
473 srcu_read_unlock(&kvm->irq_srcu, idx);
477 EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
479 void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
481 struct kvm_irq_ack_notifier *kian;
483 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
485 if (kian->gsi == gsi)
486 kian->irq_acked(kian);
489 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
493 trace_kvm_ack_irq(irqchip, pin);
495 idx = srcu_read_lock(&kvm->irq_srcu);
496 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
498 kvm_notify_acked_gsi(kvm, gsi);
499 srcu_read_unlock(&kvm->irq_srcu, idx);
502 void kvm_register_irq_ack_notifier(struct kvm *kvm,
503 struct kvm_irq_ack_notifier *kian)
505 mutex_lock(&kvm->irq_lock);
506 hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
507 mutex_unlock(&kvm->irq_lock);
508 kvm_arch_post_irq_ack_notifier_list_update(kvm);
511 void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
512 struct kvm_irq_ack_notifier *kian)
514 mutex_lock(&kvm->irq_lock);
515 hlist_del_init_rcu(&kian->link);
516 mutex_unlock(&kvm->irq_lock);
517 synchronize_srcu(&kvm->irq_srcu);
518 kvm_arch_post_irq_ack_notifier_list_update(kvm);
523 kvm_eventfd_init(struct kvm *kvm)
525 #ifdef CONFIG_HAVE_KVM_IRQFD
526 spin_lock_init(&kvm->irqfds.lock);
527 INIT_LIST_HEAD(&kvm->irqfds.items);
528 INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
529 mutex_init(&kvm->irqfds.resampler_lock);
531 INIT_LIST_HEAD(&kvm->ioeventfds);
534 #ifdef CONFIG_HAVE_KVM_IRQFD
536 * shutdown any irqfd's that match fd+gsi
539 kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
541 struct kvm_kernel_irqfd *irqfd, *tmp;
542 struct eventfd_ctx *eventfd;
544 eventfd = eventfd_ctx_fdget(args->fd);
546 return PTR_ERR(eventfd);
548 spin_lock_irq(&kvm->irqfds.lock);
550 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
551 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
553 * This clearing of irq_entry.type is needed for when
554 * another thread calls kvm_irq_routing_update before
555 * we flush workqueue below (we synchronize with
556 * kvm_irq_routing_update using irqfds.lock).
558 write_seqcount_begin(&irqfd->irq_entry_sc);
559 irqfd->irq_entry.type = 0;
560 write_seqcount_end(&irqfd->irq_entry_sc);
561 irqfd_deactivate(irqfd);
565 spin_unlock_irq(&kvm->irqfds.lock);
566 eventfd_ctx_put(eventfd);
569 * Block until we know all outstanding shutdown jobs have completed
570 * so that we guarantee there will not be any more interrupts on this
571 * gsi once this deassign function returns.
573 flush_workqueue(irqfd_cleanup_wq);
579 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
581 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
584 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
585 return kvm_irqfd_deassign(kvm, args);
587 return kvm_irqfd_assign(kvm, args);
591 * This function is called as the kvm VM fd is being released. Shutdown all
592 * irqfds that still remain open
595 kvm_irqfd_release(struct kvm *kvm)
597 struct kvm_kernel_irqfd *irqfd, *tmp;
599 spin_lock_irq(&kvm->irqfds.lock);
601 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
602 irqfd_deactivate(irqfd);
604 spin_unlock_irq(&kvm->irqfds.lock);
607 * Block until we know all outstanding shutdown jobs have completed
608 * since we do not take a kvm* reference.
610 flush_workqueue(irqfd_cleanup_wq);
615 * Take note of a change in irq routing.
616 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
618 void kvm_irq_routing_update(struct kvm *kvm)
620 struct kvm_kernel_irqfd *irqfd;
622 spin_lock_irq(&kvm->irqfds.lock);
624 list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
625 irqfd_update(kvm, irqfd);
627 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
628 if (irqfd->producer) {
629 int ret = kvm_arch_update_irqfd_routing(
630 irqfd->kvm, irqfd->producer->irq,
637 spin_unlock_irq(&kvm->irqfds.lock);
641 * create a host-wide workqueue for issuing deferred shutdown requests
642 * aggregated from all vm* instances. We need our own isolated
643 * queue to ease flushing work items when a VM exits.
645 int kvm_irqfd_init(void)
647 irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
648 if (!irqfd_cleanup_wq)
654 void kvm_irqfd_exit(void)
656 destroy_workqueue(irqfd_cleanup_wq);
661 * --------------------------------------------------------------------
662 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
664 * userspace can register a PIO/MMIO address with an eventfd for receiving
665 * notification when the memory has been touched.
666 * --------------------------------------------------------------------
670 struct list_head list;
673 struct eventfd_ctx *eventfd;
675 struct kvm_io_device dev;
680 static inline struct _ioeventfd *
681 to_ioeventfd(struct kvm_io_device *dev)
683 return container_of(dev, struct _ioeventfd, dev);
687 ioeventfd_release(struct _ioeventfd *p)
689 eventfd_ctx_put(p->eventfd);
695 ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
700 /* address must be precise for a hit */
704 /* length = 0 means only look at the address, so always a hit */
707 if (len != p->length)
708 /* address-range must be precise for a hit */
712 /* all else equal, wildcard is always a hit */
715 /* otherwise, we have to actually compare the data */
717 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
736 return _val == p->datamatch ? true : false;
739 /* MMIO/PIO writes trigger an event if the addr/val match */
741 ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
742 int len, const void *val)
744 struct _ioeventfd *p = to_ioeventfd(this);
746 if (!ioeventfd_in_range(p, addr, len, val))
749 eventfd_signal(p->eventfd, 1);
754 * This function is called as KVM is completely shutting down. We do not
755 * need to worry about locking just nuke anything we have as quickly as possible
758 ioeventfd_destructor(struct kvm_io_device *this)
760 struct _ioeventfd *p = to_ioeventfd(this);
762 ioeventfd_release(p);
765 static const struct kvm_io_device_ops ioeventfd_ops = {
766 .write = ioeventfd_write,
767 .destructor = ioeventfd_destructor,
770 /* assumes kvm->slots_lock held */
772 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
774 struct _ioeventfd *_p;
776 list_for_each_entry(_p, &kvm->ioeventfds, list)
777 if (_p->bus_idx == p->bus_idx &&
778 _p->addr == p->addr &&
779 (!_p->length || !p->length ||
780 (_p->length == p->length &&
781 (_p->wildcard || p->wildcard ||
782 _p->datamatch == p->datamatch))))
788 static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
790 if (flags & KVM_IOEVENTFD_FLAG_PIO)
792 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
793 return KVM_VIRTIO_CCW_NOTIFY_BUS;
797 static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
798 enum kvm_bus bus_idx,
799 struct kvm_ioeventfd *args)
802 struct eventfd_ctx *eventfd;
803 struct _ioeventfd *p;
806 eventfd = eventfd_ctx_fdget(args->fd);
808 return PTR_ERR(eventfd);
810 p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
816 INIT_LIST_HEAD(&p->list);
817 p->addr = args->addr;
818 p->bus_idx = bus_idx;
819 p->length = args->len;
820 p->eventfd = eventfd;
822 /* The datamatch feature is optional, otherwise this is a wildcard */
823 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
824 p->datamatch = args->datamatch;
828 mutex_lock(&kvm->slots_lock);
830 /* Verify that there isn't a match already */
831 if (ioeventfd_check_collision(kvm, p)) {
836 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
838 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
843 kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
844 list_add_tail(&p->list, &kvm->ioeventfds);
846 mutex_unlock(&kvm->slots_lock);
851 mutex_unlock(&kvm->slots_lock);
855 eventfd_ctx_put(eventfd);
861 kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
862 struct kvm_ioeventfd *args)
864 struct _ioeventfd *p, *tmp;
865 struct eventfd_ctx *eventfd;
866 struct kvm_io_bus *bus;
869 eventfd = eventfd_ctx_fdget(args->fd);
871 return PTR_ERR(eventfd);
873 mutex_lock(&kvm->slots_lock);
875 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
876 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
878 if (p->bus_idx != bus_idx ||
879 p->eventfd != eventfd ||
880 p->addr != args->addr ||
881 p->length != args->len ||
882 p->wildcard != wildcard)
885 if (!p->wildcard && p->datamatch != args->datamatch)
888 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
889 bus = kvm_get_bus(kvm, bus_idx);
891 bus->ioeventfd_count--;
892 ioeventfd_release(p);
897 mutex_unlock(&kvm->slots_lock);
899 eventfd_ctx_put(eventfd);
904 static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
906 enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
907 int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
909 if (!args->len && bus_idx == KVM_MMIO_BUS)
910 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
916 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
918 enum kvm_bus bus_idx;
921 bus_idx = ioeventfd_bus_from_flags(args->flags);
922 /* must be natural-word sized, or 0 to ignore length */
934 /* check for range overflow */
935 if (args->addr + args->len < args->addr)
938 /* check for extra flags that we don't understand */
939 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
942 /* ioeventfd with no length can't be combined with DATAMATCH */
943 if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
946 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
950 /* When length is ignored, MMIO is also put on a separate bus, for
953 if (!args->len && bus_idx == KVM_MMIO_BUS) {
954 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
962 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
968 kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
970 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
971 return kvm_deassign_ioeventfd(kvm, args);
973 return kvm_assign_ioeventfd(kvm, args);