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>
39 #ifdef __KVM_HAVE_IOAPIC
44 #ifdef CONFIG_HAVE_KVM_IRQFD
46 * --------------------------------------------------------------------
47 * irqfd: Allows an fd to be used to inject an interrupt to the guest
49 * Credit goes to Avi Kivity for the original idea.
50 * --------------------------------------------------------------------
54 * Resampling irqfds are a special variety of irqfds used to emulate
55 * level triggered interrupts. The interrupt is asserted on eventfd
56 * trigger. On acknowledgement through the irq ack notifier, the
57 * interrupt is de-asserted and userspace is notified through the
58 * resamplefd. All resamplers on the same gsi are de-asserted
59 * together, so we don't need to track the state of each individual
60 * user. We can also therefore share the same irq source ID.
62 struct _irqfd_resampler
{
65 * List of resampling struct _irqfd objects sharing this gsi.
66 * RCU list modified under kvm->irqfds.resampler_lock
68 struct list_head list
;
69 struct kvm_irq_ack_notifier notifier
;
71 * Entry in list of kvm->irqfd.resampler_list. Use for sharing
72 * resamplers among irqfds on the same gsi.
73 * Accessed and modified under kvm->irqfds.resampler_lock
75 struct list_head link
;
79 /* Used for MSI fast-path */
82 /* Update side is protected by irqfds.lock */
83 struct kvm_kernel_irq_routing_entry irq_entry
;
84 seqcount_t irq_entry_sc
;
85 /* Used for level IRQ fast-path */
87 struct work_struct inject
;
88 /* The resampler used by this irqfd (resampler-only) */
89 struct _irqfd_resampler
*resampler
;
90 /* Eventfd notified on resample (resampler-only) */
91 struct eventfd_ctx
*resamplefd
;
92 /* Entry in list of irqfds for a resampler (resampler-only) */
93 struct list_head resampler_link
;
94 /* Used for setup/shutdown */
95 struct eventfd_ctx
*eventfd
;
96 struct list_head list
;
98 struct work_struct shutdown
;
101 static struct workqueue_struct
*irqfd_cleanup_wq
;
104 irqfd_inject(struct work_struct
*work
)
106 struct _irqfd
*irqfd
= container_of(work
, struct _irqfd
, inject
);
107 struct kvm
*kvm
= irqfd
->kvm
;
109 if (!irqfd
->resampler
) {
110 kvm_set_irq(kvm
, KVM_USERSPACE_IRQ_SOURCE_ID
, irqfd
->gsi
, 1,
112 kvm_set_irq(kvm
, KVM_USERSPACE_IRQ_SOURCE_ID
, irqfd
->gsi
, 0,
115 kvm_set_irq(kvm
, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID
,
116 irqfd
->gsi
, 1, false);
120 * Since resampler irqfds share an IRQ source ID, we de-assert once
121 * then notify all of the resampler irqfds using this GSI. We can't
122 * do multiple de-asserts or we risk racing with incoming re-asserts.
125 irqfd_resampler_ack(struct kvm_irq_ack_notifier
*kian
)
127 struct _irqfd_resampler
*resampler
;
129 struct _irqfd
*irqfd
;
132 resampler
= container_of(kian
, struct _irqfd_resampler
, notifier
);
133 kvm
= resampler
->kvm
;
135 kvm_set_irq(kvm
, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID
,
136 resampler
->notifier
.gsi
, 0, false);
138 idx
= srcu_read_lock(&kvm
->irq_srcu
);
140 list_for_each_entry_rcu(irqfd
, &resampler
->list
, resampler_link
)
141 eventfd_signal(irqfd
->resamplefd
, 1);
143 srcu_read_unlock(&kvm
->irq_srcu
, idx
);
147 irqfd_resampler_shutdown(struct _irqfd
*irqfd
)
149 struct _irqfd_resampler
*resampler
= irqfd
->resampler
;
150 struct kvm
*kvm
= resampler
->kvm
;
152 mutex_lock(&kvm
->irqfds
.resampler_lock
);
154 list_del_rcu(&irqfd
->resampler_link
);
155 synchronize_srcu(&kvm
->irq_srcu
);
157 if (list_empty(&resampler
->list
)) {
158 list_del(&resampler
->link
);
159 kvm_unregister_irq_ack_notifier(kvm
, &resampler
->notifier
);
160 kvm_set_irq(kvm
, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID
,
161 resampler
->notifier
.gsi
, 0, false);
165 mutex_unlock(&kvm
->irqfds
.resampler_lock
);
169 * Race-free decouple logic (ordering is critical)
172 irqfd_shutdown(struct work_struct
*work
)
174 struct _irqfd
*irqfd
= container_of(work
, struct _irqfd
, shutdown
);
178 * Synchronize with the wait-queue and unhook ourselves to prevent
181 eventfd_ctx_remove_wait_queue(irqfd
->eventfd
, &irqfd
->wait
, &cnt
);
184 * We know no new events will be scheduled at this point, so block
185 * until all previously outstanding events have completed
187 flush_work(&irqfd
->inject
);
189 if (irqfd
->resampler
) {
190 irqfd_resampler_shutdown(irqfd
);
191 eventfd_ctx_put(irqfd
->resamplefd
);
195 * It is now safe to release the object's resources
197 eventfd_ctx_put(irqfd
->eventfd
);
202 /* assumes kvm->irqfds.lock is held */
204 irqfd_is_active(struct _irqfd
*irqfd
)
206 return list_empty(&irqfd
->list
) ? false : true;
210 * Mark the irqfd as inactive and schedule it for removal
212 * assumes kvm->irqfds.lock is held
215 irqfd_deactivate(struct _irqfd
*irqfd
)
217 BUG_ON(!irqfd_is_active(irqfd
));
219 list_del_init(&irqfd
->list
);
221 queue_work(irqfd_cleanup_wq
, &irqfd
->shutdown
);
225 * Called with wqh->lock held and interrupts disabled
228 irqfd_wakeup(wait_queue_t
*wait
, unsigned mode
, int sync
, void *key
)
230 struct _irqfd
*irqfd
= container_of(wait
, struct _irqfd
, wait
);
231 unsigned long flags
= (unsigned long)key
;
232 struct kvm_kernel_irq_routing_entry irq
;
233 struct kvm
*kvm
= irqfd
->kvm
;
237 if (flags
& POLLIN
) {
238 idx
= srcu_read_lock(&kvm
->irq_srcu
);
240 seq
= read_seqcount_begin(&irqfd
->irq_entry_sc
);
241 irq
= irqfd
->irq_entry
;
242 } while (read_seqcount_retry(&irqfd
->irq_entry_sc
, seq
));
243 /* An event has been signaled, inject an interrupt */
244 if (irq
.type
== KVM_IRQ_ROUTING_MSI
)
245 kvm_set_msi(&irq
, kvm
, KVM_USERSPACE_IRQ_SOURCE_ID
, 1,
248 schedule_work(&irqfd
->inject
);
249 srcu_read_unlock(&kvm
->irq_srcu
, idx
);
252 if (flags
& POLLHUP
) {
253 /* The eventfd is closing, detach from KVM */
256 spin_lock_irqsave(&kvm
->irqfds
.lock
, flags
);
259 * We must check if someone deactivated the irqfd before
260 * we could acquire the irqfds.lock since the item is
261 * deactivated from the KVM side before it is unhooked from
262 * the wait-queue. If it is already deactivated, we can
263 * simply return knowing the other side will cleanup for us.
264 * We cannot race against the irqfd going away since the
265 * other side is required to acquire wqh->lock, which we hold
267 if (irqfd_is_active(irqfd
))
268 irqfd_deactivate(irqfd
);
270 spin_unlock_irqrestore(&kvm
->irqfds
.lock
, flags
);
277 irqfd_ptable_queue_proc(struct file
*file
, wait_queue_head_t
*wqh
,
280 struct _irqfd
*irqfd
= container_of(pt
, struct _irqfd
, pt
);
281 add_wait_queue(wqh
, &irqfd
->wait
);
284 /* Must be called under irqfds.lock */
285 static void irqfd_update(struct kvm
*kvm
, struct _irqfd
*irqfd
)
287 struct kvm_kernel_irq_routing_entry
*e
;
288 struct kvm_kernel_irq_routing_entry entries
[KVM_NR_IRQCHIPS
];
291 n_entries
= kvm_irq_map_gsi(kvm
, entries
, irqfd
->gsi
);
293 write_seqcount_begin(&irqfd
->irq_entry_sc
);
295 irqfd
->irq_entry
.type
= 0;
298 for (i
= 0; i
< n_entries
; ++i
, ++e
) {
299 /* Only fast-path MSI. */
300 if (e
->type
== KVM_IRQ_ROUTING_MSI
)
301 irqfd
->irq_entry
= *e
;
304 write_seqcount_end(&irqfd
->irq_entry_sc
);
308 kvm_irqfd_assign(struct kvm
*kvm
, struct kvm_irqfd
*args
)
310 struct _irqfd
*irqfd
, *tmp
;
312 struct eventfd_ctx
*eventfd
= NULL
, *resamplefd
= NULL
;
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 #ifdef __KVM_HAVE_IOAPIC
496 kvm_vcpu_request_scan_ioapic(kvm
);
500 void kvm_unregister_irq_ack_notifier(struct kvm
*kvm
,
501 struct kvm_irq_ack_notifier
*kian
)
503 mutex_lock(&kvm
->irq_lock
);
504 hlist_del_init_rcu(&kian
->link
);
505 mutex_unlock(&kvm
->irq_lock
);
506 synchronize_srcu(&kvm
->irq_srcu
);
507 #ifdef __KVM_HAVE_IOAPIC
508 kvm_vcpu_request_scan_ioapic(kvm
);
514 kvm_eventfd_init(struct kvm
*kvm
)
516 #ifdef CONFIG_HAVE_KVM_IRQFD
517 spin_lock_init(&kvm
->irqfds
.lock
);
518 INIT_LIST_HEAD(&kvm
->irqfds
.items
);
519 INIT_LIST_HEAD(&kvm
->irqfds
.resampler_list
);
520 mutex_init(&kvm
->irqfds
.resampler_lock
);
522 INIT_LIST_HEAD(&kvm
->ioeventfds
);
525 #ifdef CONFIG_HAVE_KVM_IRQFD
527 * shutdown any irqfd's that match fd+gsi
530 kvm_irqfd_deassign(struct kvm
*kvm
, struct kvm_irqfd
*args
)
532 struct _irqfd
*irqfd
, *tmp
;
533 struct eventfd_ctx
*eventfd
;
535 eventfd
= eventfd_ctx_fdget(args
->fd
);
537 return PTR_ERR(eventfd
);
539 spin_lock_irq(&kvm
->irqfds
.lock
);
541 list_for_each_entry_safe(irqfd
, tmp
, &kvm
->irqfds
.items
, list
) {
542 if (irqfd
->eventfd
== eventfd
&& irqfd
->gsi
== args
->gsi
) {
544 * This clearing of irq_entry.type is needed for when
545 * another thread calls kvm_irq_routing_update before
546 * we flush workqueue below (we synchronize with
547 * kvm_irq_routing_update using irqfds.lock).
549 write_seqcount_begin(&irqfd
->irq_entry_sc
);
550 irqfd
->irq_entry
.type
= 0;
551 write_seqcount_end(&irqfd
->irq_entry_sc
);
552 irqfd_deactivate(irqfd
);
556 spin_unlock_irq(&kvm
->irqfds
.lock
);
557 eventfd_ctx_put(eventfd
);
560 * Block until we know all outstanding shutdown jobs have completed
561 * so that we guarantee there will not be any more interrupts on this
562 * gsi once this deassign function returns.
564 flush_workqueue(irqfd_cleanup_wq
);
570 kvm_irqfd(struct kvm
*kvm
, struct kvm_irqfd
*args
)
572 if (args
->flags
& ~(KVM_IRQFD_FLAG_DEASSIGN
| KVM_IRQFD_FLAG_RESAMPLE
))
575 if (args
->flags
& KVM_IRQFD_FLAG_DEASSIGN
)
576 return kvm_irqfd_deassign(kvm
, args
);
578 return kvm_irqfd_assign(kvm
, args
);
582 * This function is called as the kvm VM fd is being released. Shutdown all
583 * irqfds that still remain open
586 kvm_irqfd_release(struct kvm
*kvm
)
588 struct _irqfd
*irqfd
, *tmp
;
590 spin_lock_irq(&kvm
->irqfds
.lock
);
592 list_for_each_entry_safe(irqfd
, tmp
, &kvm
->irqfds
.items
, list
)
593 irqfd_deactivate(irqfd
);
595 spin_unlock_irq(&kvm
->irqfds
.lock
);
598 * Block until we know all outstanding shutdown jobs have completed
599 * since we do not take a kvm* reference.
601 flush_workqueue(irqfd_cleanup_wq
);
606 * Take note of a change in irq routing.
607 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
609 void kvm_irq_routing_update(struct kvm
*kvm
)
611 struct _irqfd
*irqfd
;
613 spin_lock_irq(&kvm
->irqfds
.lock
);
615 list_for_each_entry(irqfd
, &kvm
->irqfds
.items
, list
)
616 irqfd_update(kvm
, irqfd
);
618 spin_unlock_irq(&kvm
->irqfds
.lock
);
622 * create a host-wide workqueue for issuing deferred shutdown requests
623 * aggregated from all vm* instances. We need our own isolated single-thread
624 * queue to prevent deadlock against flushing the normal work-queue.
626 int kvm_irqfd_init(void)
628 irqfd_cleanup_wq
= create_singlethread_workqueue("kvm-irqfd-cleanup");
629 if (!irqfd_cleanup_wq
)
635 void kvm_irqfd_exit(void)
637 destroy_workqueue(irqfd_cleanup_wq
);
642 * --------------------------------------------------------------------
643 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
645 * userspace can register a PIO/MMIO address with an eventfd for receiving
646 * notification when the memory has been touched.
647 * --------------------------------------------------------------------
651 struct list_head list
;
654 struct eventfd_ctx
*eventfd
;
656 struct kvm_io_device dev
;
661 static inline struct _ioeventfd
*
662 to_ioeventfd(struct kvm_io_device
*dev
)
664 return container_of(dev
, struct _ioeventfd
, dev
);
668 ioeventfd_release(struct _ioeventfd
*p
)
670 eventfd_ctx_put(p
->eventfd
);
676 ioeventfd_in_range(struct _ioeventfd
*p
, gpa_t addr
, int len
, const void *val
)
681 /* address must be precise for a hit */
685 /* length = 0 means only look at the address, so always a hit */
688 if (len
!= p
->length
)
689 /* address-range must be precise for a hit */
693 /* all else equal, wildcard is always a hit */
696 /* otherwise, we have to actually compare the data */
698 BUG_ON(!IS_ALIGNED((unsigned long)val
, len
));
717 return _val
== p
->datamatch
? true : false;
720 /* MMIO/PIO writes trigger an event if the addr/val match */
722 ioeventfd_write(struct kvm_io_device
*this, gpa_t addr
, int len
,
725 struct _ioeventfd
*p
= to_ioeventfd(this);
727 if (!ioeventfd_in_range(p
, addr
, len
, val
))
730 eventfd_signal(p
->eventfd
, 1);
735 * This function is called as KVM is completely shutting down. We do not
736 * need to worry about locking just nuke anything we have as quickly as possible
739 ioeventfd_destructor(struct kvm_io_device
*this)
741 struct _ioeventfd
*p
= to_ioeventfd(this);
743 ioeventfd_release(p
);
746 static const struct kvm_io_device_ops ioeventfd_ops
= {
747 .write
= ioeventfd_write
,
748 .destructor
= ioeventfd_destructor
,
751 /* assumes kvm->slots_lock held */
753 ioeventfd_check_collision(struct kvm
*kvm
, struct _ioeventfd
*p
)
755 struct _ioeventfd
*_p
;
757 list_for_each_entry(_p
, &kvm
->ioeventfds
, list
)
758 if (_p
->bus_idx
== p
->bus_idx
&&
759 _p
->addr
== p
->addr
&&
760 (!_p
->length
|| !p
->length
||
761 (_p
->length
== p
->length
&&
762 (_p
->wildcard
|| p
->wildcard
||
763 _p
->datamatch
== p
->datamatch
))))
769 static enum kvm_bus
ioeventfd_bus_from_flags(__u32 flags
)
771 if (flags
& KVM_IOEVENTFD_FLAG_PIO
)
773 if (flags
& KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY
)
774 return KVM_VIRTIO_CCW_NOTIFY_BUS
;
779 kvm_assign_ioeventfd(struct kvm
*kvm
, struct kvm_ioeventfd
*args
)
781 enum kvm_bus bus_idx
;
782 struct _ioeventfd
*p
;
783 struct eventfd_ctx
*eventfd
;
786 bus_idx
= ioeventfd_bus_from_flags(args
->flags
);
787 /* must be natural-word sized, or 0 to ignore length */
799 /* check for range overflow */
800 if (args
->addr
+ args
->len
< args
->addr
)
803 /* check for extra flags that we don't understand */
804 if (args
->flags
& ~KVM_IOEVENTFD_VALID_FLAG_MASK
)
807 /* ioeventfd with no length can't be combined with DATAMATCH */
809 args
->flags
& (KVM_IOEVENTFD_FLAG_PIO
|
810 KVM_IOEVENTFD_FLAG_DATAMATCH
))
813 eventfd
= eventfd_ctx_fdget(args
->fd
);
815 return PTR_ERR(eventfd
);
817 p
= kzalloc(sizeof(*p
), GFP_KERNEL
);
823 INIT_LIST_HEAD(&p
->list
);
824 p
->addr
= args
->addr
;
825 p
->bus_idx
= bus_idx
;
826 p
->length
= args
->len
;
827 p
->eventfd
= eventfd
;
829 /* The datamatch feature is optional, otherwise this is a wildcard */
830 if (args
->flags
& KVM_IOEVENTFD_FLAG_DATAMATCH
)
831 p
->datamatch
= args
->datamatch
;
835 mutex_lock(&kvm
->slots_lock
);
837 /* Verify that there isn't a match already */
838 if (ioeventfd_check_collision(kvm
, p
)) {
843 kvm_iodevice_init(&p
->dev
, &ioeventfd_ops
);
845 ret
= kvm_io_bus_register_dev(kvm
, bus_idx
, p
->addr
, p
->length
,
850 /* When length is ignored, MMIO is also put on a separate bus, for
853 if (!args
->len
&& !(args
->flags
& KVM_IOEVENTFD_FLAG_PIO
)) {
854 ret
= kvm_io_bus_register_dev(kvm
, KVM_FAST_MMIO_BUS
,
855 p
->addr
, 0, &p
->dev
);
860 kvm
->buses
[bus_idx
]->ioeventfd_count
++;
861 list_add_tail(&p
->list
, &kvm
->ioeventfds
);
863 mutex_unlock(&kvm
->slots_lock
);
868 kvm_io_bus_unregister_dev(kvm
, bus_idx
, &p
->dev
);
870 mutex_unlock(&kvm
->slots_lock
);
874 eventfd_ctx_put(eventfd
);
880 kvm_deassign_ioeventfd(struct kvm
*kvm
, struct kvm_ioeventfd
*args
)
882 enum kvm_bus bus_idx
;
883 struct _ioeventfd
*p
, *tmp
;
884 struct eventfd_ctx
*eventfd
;
887 bus_idx
= ioeventfd_bus_from_flags(args
->flags
);
888 eventfd
= eventfd_ctx_fdget(args
->fd
);
890 return PTR_ERR(eventfd
);
892 mutex_lock(&kvm
->slots_lock
);
894 list_for_each_entry_safe(p
, tmp
, &kvm
->ioeventfds
, list
) {
895 bool wildcard
= !(args
->flags
& KVM_IOEVENTFD_FLAG_DATAMATCH
);
897 if (p
->bus_idx
!= bus_idx
||
898 p
->eventfd
!= eventfd
||
899 p
->addr
!= args
->addr
||
900 p
->length
!= args
->len
||
901 p
->wildcard
!= wildcard
)
904 if (!p
->wildcard
&& p
->datamatch
!= args
->datamatch
)
907 kvm_io_bus_unregister_dev(kvm
, bus_idx
, &p
->dev
);
909 kvm_io_bus_unregister_dev(kvm
, KVM_FAST_MMIO_BUS
,
912 kvm
->buses
[bus_idx
]->ioeventfd_count
--;
913 ioeventfd_release(p
);
918 mutex_unlock(&kvm
->slots_lock
);
920 eventfd_ctx_put(eventfd
);
926 kvm_ioeventfd(struct kvm
*kvm
, struct kvm_ioeventfd
*args
)
928 if (args
->flags
& KVM_IOEVENTFD_FLAG_DEASSIGN
)
929 return kvm_deassign_ioeventfd(kvm
, args
);
931 return kvm_assign_ioeventfd(kvm
, args
);