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1/*
2 * kvm eventfd support - use eventfd objects to signal various KVM events
3 *
4 * Copyright 2009 Novell. All Rights Reserved.
5 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
6 *
7 * Author:
8 * Gregory Haskins <ghaskins@novell.com>
9 *
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.
13 *
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.
18 *
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.
22 */
23
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/slab.h>
35
36#include "iodev.h"
37
38#ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
39/*
40 * --------------------------------------------------------------------
41 * irqfd: Allows an fd to be used to inject an interrupt to the guest
42 *
43 * Credit goes to Avi Kivity for the original idea.
44 * --------------------------------------------------------------------
45 */
46
47/*
48 * Resampling irqfds are a special variety of irqfds used to emulate
49 * level triggered interrupts. The interrupt is asserted on eventfd
50 * trigger. On acknowledgement through the irq ack notifier, the
51 * interrupt is de-asserted and userspace is notified through the
52 * resamplefd. All resamplers on the same gsi are de-asserted
53 * together, so we don't need to track the state of each individual
54 * user. We can also therefore share the same irq source ID.
55 */
56struct _irqfd_resampler {
57 struct kvm *kvm;
58 /*
59 * List of resampling struct _irqfd objects sharing this gsi.
60 * RCU list modified under kvm->irqfds.resampler_lock
61 */
62 struct list_head list;
63 struct kvm_irq_ack_notifier notifier;
64 /*
65 * Entry in list of kvm->irqfd.resampler_list. Use for sharing
66 * resamplers among irqfds on the same gsi.
67 * Accessed and modified under kvm->irqfds.resampler_lock
68 */
69 struct list_head link;
70};
71
72struct _irqfd {
73 /* Used for MSI fast-path */
74 struct kvm *kvm;
75 wait_queue_t wait;
76 /* Update side is protected by irqfds.lock */
77 struct kvm_kernel_irq_routing_entry __rcu *irq_entry;
78 /* Used for level IRQ fast-path */
79 int gsi;
80 struct work_struct inject;
81 /* The resampler used by this irqfd (resampler-only) */
82 struct _irqfd_resampler *resampler;
83 /* Eventfd notified on resample (resampler-only) */
84 struct eventfd_ctx *resamplefd;
85 /* Entry in list of irqfds for a resampler (resampler-only) */
86 struct list_head resampler_link;
87 /* Used for setup/shutdown */
88 struct eventfd_ctx *eventfd;
89 struct list_head list;
90 poll_table pt;
91 struct work_struct shutdown;
92};
93
94static struct workqueue_struct *irqfd_cleanup_wq;
95
96static void
97irqfd_inject(struct work_struct *work)
98{
99 struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
100 struct kvm *kvm = irqfd->kvm;
101
102 if (!irqfd->resampler) {
103 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
104 false);
105 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
106 false);
107 } else
108 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
109 irqfd->gsi, 1, false);
110}
111
112/*
113 * Since resampler irqfds share an IRQ source ID, we de-assert once
114 * then notify all of the resampler irqfds using this GSI. We can't
115 * do multiple de-asserts or we risk racing with incoming re-asserts.
116 */
117static void
118irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
119{
120 struct _irqfd_resampler *resampler;
121 struct _irqfd *irqfd;
122
123 resampler = container_of(kian, struct _irqfd_resampler, notifier);
124
125 kvm_set_irq(resampler->kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
126 resampler->notifier.gsi, 0, false);
127
128 rcu_read_lock();
129
130 list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link)
131 eventfd_signal(irqfd->resamplefd, 1);
132
133 rcu_read_unlock();
134}
135
136static void
137irqfd_resampler_shutdown(struct _irqfd *irqfd)
138{
139 struct _irqfd_resampler *resampler = irqfd->resampler;
140 struct kvm *kvm = resampler->kvm;
141
142 mutex_lock(&kvm->irqfds.resampler_lock);
143
144 list_del_rcu(&irqfd->resampler_link);
145 synchronize_rcu();
146
147 if (list_empty(&resampler->list)) {
148 list_del(&resampler->link);
149 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
150 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
151 resampler->notifier.gsi, 0, false);
152 kfree(resampler);
153 }
154
155 mutex_unlock(&kvm->irqfds.resampler_lock);
156}
157
158/*
159 * Race-free decouple logic (ordering is critical)
160 */
161static void
162irqfd_shutdown(struct work_struct *work)
163{
164 struct _irqfd *irqfd = container_of(work, struct _irqfd, shutdown);
165 u64 cnt;
166
167 /*
168 * Synchronize with the wait-queue and unhook ourselves to prevent
169 * further events.
170 */
171 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
172
173 /*
174 * We know no new events will be scheduled at this point, so block
175 * until all previously outstanding events have completed
176 */
177 flush_work(&irqfd->inject);
178
179 if (irqfd->resampler) {
180 irqfd_resampler_shutdown(irqfd);
181 eventfd_ctx_put(irqfd->resamplefd);
182 }
183
184 /*
185 * It is now safe to release the object's resources
186 */
187 eventfd_ctx_put(irqfd->eventfd);
188 kfree(irqfd);
189}
190
191
192/* assumes kvm->irqfds.lock is held */
193static bool
194irqfd_is_active(struct _irqfd *irqfd)
195{
196 return list_empty(&irqfd->list) ? false : true;
197}
198
199/*
200 * Mark the irqfd as inactive and schedule it for removal
201 *
202 * assumes kvm->irqfds.lock is held
203 */
204static void
205irqfd_deactivate(struct _irqfd *irqfd)
206{
207 BUG_ON(!irqfd_is_active(irqfd));
208
209 list_del_init(&irqfd->list);
210
211 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
212}
213
214/*
215 * Called with wqh->lock held and interrupts disabled
216 */
217static int
218irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
219{
220 struct _irqfd *irqfd = container_of(wait, struct _irqfd, wait);
221 unsigned long flags = (unsigned long)key;
222 struct kvm_kernel_irq_routing_entry *irq;
223 struct kvm *kvm = irqfd->kvm;
224
225 if (flags & POLLIN) {
226 rcu_read_lock();
227 irq = rcu_dereference(irqfd->irq_entry);
228 /* An event has been signaled, inject an interrupt */
229 if (irq)
230 kvm_set_msi(irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1,
231 false);
232 else
233 schedule_work(&irqfd->inject);
234 rcu_read_unlock();
235 }
236
237 if (flags & POLLHUP) {
238 /* The eventfd is closing, detach from KVM */
239 unsigned long flags;
240
241 spin_lock_irqsave(&kvm->irqfds.lock, flags);
242
243 /*
244 * We must check if someone deactivated the irqfd before
245 * we could acquire the irqfds.lock since the item is
246 * deactivated from the KVM side before it is unhooked from
247 * the wait-queue. If it is already deactivated, we can
248 * simply return knowing the other side will cleanup for us.
249 * We cannot race against the irqfd going away since the
250 * other side is required to acquire wqh->lock, which we hold
251 */
252 if (irqfd_is_active(irqfd))
253 irqfd_deactivate(irqfd);
254
255 spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
256 }
257
258 return 0;
259}
260
261static void
262irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
263 poll_table *pt)
264{
265 struct _irqfd *irqfd = container_of(pt, struct _irqfd, pt);
266 add_wait_queue(wqh, &irqfd->wait);
267}
268
269/* Must be called under irqfds.lock */
270static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd,
271 struct kvm_irq_routing_table *irq_rt)
272{
273 struct kvm_kernel_irq_routing_entry *e;
274
275 if (irqfd->gsi >= irq_rt->nr_rt_entries) {
276 rcu_assign_pointer(irqfd->irq_entry, NULL);
277 return;
278 }
279
280 hlist_for_each_entry(e, &irq_rt->map[irqfd->gsi], link) {
281 /* Only fast-path MSI. */
282 if (e->type == KVM_IRQ_ROUTING_MSI)
283 rcu_assign_pointer(irqfd->irq_entry, e);
284 else
285 rcu_assign_pointer(irqfd->irq_entry, NULL);
286 }
287}
288
289static int
290kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
291{
292 struct kvm_irq_routing_table *irq_rt;
293 struct _irqfd *irqfd, *tmp;
294 struct fd f;
295 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
296 int ret;
297 unsigned int events;
298
299 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
300 if (!irqfd)
301 return -ENOMEM;
302
303 irqfd->kvm = kvm;
304 irqfd->gsi = args->gsi;
305 INIT_LIST_HEAD(&irqfd->list);
306 INIT_WORK(&irqfd->inject, irqfd_inject);
307 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
308
309 f = fdget(args->fd);
310 if (!f.file) {
311 ret = -EBADF;
312 goto out;
313 }
314
315 eventfd = eventfd_ctx_fileget(f.file);
316 if (IS_ERR(eventfd)) {
317 ret = PTR_ERR(eventfd);
318 goto fail;
319 }
320
321 irqfd->eventfd = eventfd;
322
323 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
324 struct _irqfd_resampler *resampler;
325
326 resamplefd = eventfd_ctx_fdget(args->resamplefd);
327 if (IS_ERR(resamplefd)) {
328 ret = PTR_ERR(resamplefd);
329 goto fail;
330 }
331
332 irqfd->resamplefd = resamplefd;
333 INIT_LIST_HEAD(&irqfd->resampler_link);
334
335 mutex_lock(&kvm->irqfds.resampler_lock);
336
337 list_for_each_entry(resampler,
338 &kvm->irqfds.resampler_list, link) {
339 if (resampler->notifier.gsi == irqfd->gsi) {
340 irqfd->resampler = resampler;
341 break;
342 }
343 }
344
345 if (!irqfd->resampler) {
346 resampler = kzalloc(sizeof(*resampler), GFP_KERNEL);
347 if (!resampler) {
348 ret = -ENOMEM;
349 mutex_unlock(&kvm->irqfds.resampler_lock);
350 goto fail;
351 }
352
353 resampler->kvm = kvm;
354 INIT_LIST_HEAD(&resampler->list);
355 resampler->notifier.gsi = irqfd->gsi;
356 resampler->notifier.irq_acked = irqfd_resampler_ack;
357 INIT_LIST_HEAD(&resampler->link);
358
359 list_add(&resampler->link, &kvm->irqfds.resampler_list);
360 kvm_register_irq_ack_notifier(kvm,
361 &resampler->notifier);
362 irqfd->resampler = resampler;
363 }
364
365 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
366 synchronize_rcu();
367
368 mutex_unlock(&kvm->irqfds.resampler_lock);
369 }
370
371 /*
372 * Install our own custom wake-up handling so we are notified via
373 * a callback whenever someone signals the underlying eventfd
374 */
375 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
376 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
377
378 spin_lock_irq(&kvm->irqfds.lock);
379
380 ret = 0;
381 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
382 if (irqfd->eventfd != tmp->eventfd)
383 continue;
384 /* This fd is used for another irq already. */
385 ret = -EBUSY;
386 spin_unlock_irq(&kvm->irqfds.lock);
387 goto fail;
388 }
389
390 irq_rt = rcu_dereference_protected(kvm->irq_routing,
391 lockdep_is_held(&kvm->irqfds.lock));
392 irqfd_update(kvm, irqfd, irq_rt);
393
394 list_add_tail(&irqfd->list, &kvm->irqfds.items);
395
396 spin_unlock_irq(&kvm->irqfds.lock);
397
398 /*
399 * Check if there was an event already pending on the eventfd
400 * before we registered, and trigger it as if we didn't miss it.
401 */
402 events = f.file->f_op->poll(f.file, &irqfd->pt);
403
404 if (events & POLLIN)
405 schedule_work(&irqfd->inject);
406
407 /*
408 * do not drop the file until the irqfd is fully initialized, otherwise
409 * we might race against the POLLHUP
410 */
411 fdput(f);
412
413 return 0;
414
415fail:
416 if (irqfd->resampler)
417 irqfd_resampler_shutdown(irqfd);
418
419 if (resamplefd && !IS_ERR(resamplefd))
420 eventfd_ctx_put(resamplefd);
421
422 if (eventfd && !IS_ERR(eventfd))
423 eventfd_ctx_put(eventfd);
424
425 fdput(f);
426
427out:
428 kfree(irqfd);
429 return ret;
430}
431#endif
432
433void
434kvm_eventfd_init(struct kvm *kvm)
435{
436#ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
437 spin_lock_init(&kvm->irqfds.lock);
438 INIT_LIST_HEAD(&kvm->irqfds.items);
439 INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
440 mutex_init(&kvm->irqfds.resampler_lock);
441#endif
442 INIT_LIST_HEAD(&kvm->ioeventfds);
443}
444
445#ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
446/*
447 * shutdown any irqfd's that match fd+gsi
448 */
449static int
450kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
451{
452 struct _irqfd *irqfd, *tmp;
453 struct eventfd_ctx *eventfd;
454
455 eventfd = eventfd_ctx_fdget(args->fd);
456 if (IS_ERR(eventfd))
457 return PTR_ERR(eventfd);
458
459 spin_lock_irq(&kvm->irqfds.lock);
460
461 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
462 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
463 /*
464 * This rcu_assign_pointer is needed for when
465 * another thread calls kvm_irq_routing_update before
466 * we flush workqueue below (we synchronize with
467 * kvm_irq_routing_update using irqfds.lock).
468 * It is paired with synchronize_rcu done by caller
469 * of that function.
470 */
471 rcu_assign_pointer(irqfd->irq_entry, NULL);
472 irqfd_deactivate(irqfd);
473 }
474 }
475
476 spin_unlock_irq(&kvm->irqfds.lock);
477 eventfd_ctx_put(eventfd);
478
479 /*
480 * Block until we know all outstanding shutdown jobs have completed
481 * so that we guarantee there will not be any more interrupts on this
482 * gsi once this deassign function returns.
483 */
484 flush_workqueue(irqfd_cleanup_wq);
485
486 return 0;
487}
488
489int
490kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
491{
492 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
493 return -EINVAL;
494
495 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
496 return kvm_irqfd_deassign(kvm, args);
497
498 return kvm_irqfd_assign(kvm, args);
499}
500
501/*
502 * This function is called as the kvm VM fd is being released. Shutdown all
503 * irqfds that still remain open
504 */
505void
506kvm_irqfd_release(struct kvm *kvm)
507{
508 struct _irqfd *irqfd, *tmp;
509
510 spin_lock_irq(&kvm->irqfds.lock);
511
512 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
513 irqfd_deactivate(irqfd);
514
515 spin_unlock_irq(&kvm->irqfds.lock);
516
517 /*
518 * Block until we know all outstanding shutdown jobs have completed
519 * since we do not take a kvm* reference.
520 */
521 flush_workqueue(irqfd_cleanup_wq);
522
523}
524
525/*
526 * Change irq_routing and irqfd.
527 * Caller must invoke synchronize_rcu afterwards.
528 */
529void kvm_irq_routing_update(struct kvm *kvm,
530 struct kvm_irq_routing_table *irq_rt)
531{
532 struct _irqfd *irqfd;
533
534 spin_lock_irq(&kvm->irqfds.lock);
535
536 rcu_assign_pointer(kvm->irq_routing, irq_rt);
537
538 list_for_each_entry(irqfd, &kvm->irqfds.items, list)
539 irqfd_update(kvm, irqfd, irq_rt);
540
541 spin_unlock_irq(&kvm->irqfds.lock);
542}
543
544/*
545 * create a host-wide workqueue for issuing deferred shutdown requests
546 * aggregated from all vm* instances. We need our own isolated single-thread
547 * queue to prevent deadlock against flushing the normal work-queue.
548 */
549int kvm_irqfd_init(void)
550{
551 irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
552 if (!irqfd_cleanup_wq)
553 return -ENOMEM;
554
555 return 0;
556}
557
558void kvm_irqfd_exit(void)
559{
560 destroy_workqueue(irqfd_cleanup_wq);
561}
562#endif
563
564/*
565 * --------------------------------------------------------------------
566 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
567 *
568 * userspace can register a PIO/MMIO address with an eventfd for receiving
569 * notification when the memory has been touched.
570 * --------------------------------------------------------------------
571 */
572
573struct _ioeventfd {
574 struct list_head list;
575 u64 addr;
576 int length;
577 struct eventfd_ctx *eventfd;
578 u64 datamatch;
579 struct kvm_io_device dev;
580 u8 bus_idx;
581 bool wildcard;
582};
583
584static inline struct _ioeventfd *
585to_ioeventfd(struct kvm_io_device *dev)
586{
587 return container_of(dev, struct _ioeventfd, dev);
588}
589
590static void
591ioeventfd_release(struct _ioeventfd *p)
592{
593 eventfd_ctx_put(p->eventfd);
594 list_del(&p->list);
595 kfree(p);
596}
597
598static bool
599ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
600{
601 u64 _val;
602
603 if (!(addr == p->addr && len == p->length))
604 /* address-range must be precise for a hit */
605 return false;
606
607 if (p->wildcard)
608 /* all else equal, wildcard is always a hit */
609 return true;
610
611 /* otherwise, we have to actually compare the data */
612
613 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
614
615 switch (len) {
616 case 1:
617 _val = *(u8 *)val;
618 break;
619 case 2:
620 _val = *(u16 *)val;
621 break;
622 case 4:
623 _val = *(u32 *)val;
624 break;
625 case 8:
626 _val = *(u64 *)val;
627 break;
628 default:
629 return false;
630 }
631
632 return _val == p->datamatch ? true : false;
633}
634
635/* MMIO/PIO writes trigger an event if the addr/val match */
636static int
637ioeventfd_write(struct kvm_io_device *this, gpa_t addr, int len,
638 const void *val)
639{
640 struct _ioeventfd *p = to_ioeventfd(this);
641
642 if (!ioeventfd_in_range(p, addr, len, val))
643 return -EOPNOTSUPP;
644
645 eventfd_signal(p->eventfd, 1);
646 return 0;
647}
648
649/*
650 * This function is called as KVM is completely shutting down. We do not
651 * need to worry about locking just nuke anything we have as quickly as possible
652 */
653static void
654ioeventfd_destructor(struct kvm_io_device *this)
655{
656 struct _ioeventfd *p = to_ioeventfd(this);
657
658 ioeventfd_release(p);
659}
660
661static const struct kvm_io_device_ops ioeventfd_ops = {
662 .write = ioeventfd_write,
663 .destructor = ioeventfd_destructor,
664};
665
666/* assumes kvm->slots_lock held */
667static bool
668ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
669{
670 struct _ioeventfd *_p;
671
672 list_for_each_entry(_p, &kvm->ioeventfds, list)
673 if (_p->bus_idx == p->bus_idx &&
674 _p->addr == p->addr && _p->length == p->length &&
675 (_p->wildcard || p->wildcard ||
676 _p->datamatch == p->datamatch))
677 return true;
678
679 return false;
680}
681
682static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
683{
684 if (flags & KVM_IOEVENTFD_FLAG_PIO)
685 return KVM_PIO_BUS;
686 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
687 return KVM_VIRTIO_CCW_NOTIFY_BUS;
688 return KVM_MMIO_BUS;
689}
690
691static int
692kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
693{
694 enum kvm_bus bus_idx;
695 struct _ioeventfd *p;
696 struct eventfd_ctx *eventfd;
697 int ret;
698
699 bus_idx = ioeventfd_bus_from_flags(args->flags);
700 /* must be natural-word sized */
701 switch (args->len) {
702 case 1:
703 case 2:
704 case 4:
705 case 8:
706 break;
707 default:
708 return -EINVAL;
709 }
710
711 /* check for range overflow */
712 if (args->addr + args->len < args->addr)
713 return -EINVAL;
714
715 /* check for extra flags that we don't understand */
716 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
717 return -EINVAL;
718
719 eventfd = eventfd_ctx_fdget(args->fd);
720 if (IS_ERR(eventfd))
721 return PTR_ERR(eventfd);
722
723 p = kzalloc(sizeof(*p), GFP_KERNEL);
724 if (!p) {
725 ret = -ENOMEM;
726 goto fail;
727 }
728
729 INIT_LIST_HEAD(&p->list);
730 p->addr = args->addr;
731 p->bus_idx = bus_idx;
732 p->length = args->len;
733 p->eventfd = eventfd;
734
735 /* The datamatch feature is optional, otherwise this is a wildcard */
736 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
737 p->datamatch = args->datamatch;
738 else
739 p->wildcard = true;
740
741 mutex_lock(&kvm->slots_lock);
742
743 /* Verify that there isn't a match already */
744 if (ioeventfd_check_collision(kvm, p)) {
745 ret = -EEXIST;
746 goto unlock_fail;
747 }
748
749 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
750
751 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
752 &p->dev);
753 if (ret < 0)
754 goto unlock_fail;
755
756 kvm->buses[bus_idx]->ioeventfd_count++;
757 list_add_tail(&p->list, &kvm->ioeventfds);
758
759 mutex_unlock(&kvm->slots_lock);
760
761 return 0;
762
763unlock_fail:
764 mutex_unlock(&kvm->slots_lock);
765
766fail:
767 kfree(p);
768 eventfd_ctx_put(eventfd);
769
770 return ret;
771}
772
773static int
774kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
775{
776 enum kvm_bus bus_idx;
777 struct _ioeventfd *p, *tmp;
778 struct eventfd_ctx *eventfd;
779 int ret = -ENOENT;
780
781 bus_idx = ioeventfd_bus_from_flags(args->flags);
782 eventfd = eventfd_ctx_fdget(args->fd);
783 if (IS_ERR(eventfd))
784 return PTR_ERR(eventfd);
785
786 mutex_lock(&kvm->slots_lock);
787
788 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
789 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
790
791 if (p->bus_idx != bus_idx ||
792 p->eventfd != eventfd ||
793 p->addr != args->addr ||
794 p->length != args->len ||
795 p->wildcard != wildcard)
796 continue;
797
798 if (!p->wildcard && p->datamatch != args->datamatch)
799 continue;
800
801 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
802 kvm->buses[bus_idx]->ioeventfd_count--;
803 ioeventfd_release(p);
804 ret = 0;
805 break;
806 }
807
808 mutex_unlock(&kvm->slots_lock);
809
810 eventfd_ctx_put(eventfd);
811
812 return ret;
813}
814
815int
816kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
817{
818 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
819 return kvm_deassign_ioeventfd(kvm, args);
820
821 return kvm_assign_ioeventfd(kvm, args);
822}
1/*
2 * kvm eventfd support - use eventfd objects to signal various KVM events
3 *
4 * Copyright 2009 Novell. All Rights Reserved.
5 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
6 *
7 * Author:
8 * Gregory Haskins <ghaskins@novell.com>
9 *
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.
13 *
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.
18 *
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.
22 */
23
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>
40
41#include <kvm/iodev.h>
42
43#ifdef CONFIG_HAVE_KVM_IRQFD
44
45static struct workqueue_struct *irqfd_cleanup_wq;
46
47static void
48irqfd_inject(struct work_struct *work)
49{
50 struct kvm_kernel_irqfd *irqfd =
51 container_of(work, struct kvm_kernel_irqfd, inject);
52 struct kvm *kvm = irqfd->kvm;
53
54 if (!irqfd->resampler) {
55 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
56 false);
57 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
58 false);
59 } else
60 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
61 irqfd->gsi, 1, false);
62}
63
64/*
65 * Since resampler irqfds share an IRQ source ID, we de-assert once
66 * then notify all of the resampler irqfds using this GSI. We can't
67 * do multiple de-asserts or we risk racing with incoming re-asserts.
68 */
69static void
70irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
71{
72 struct kvm_kernel_irqfd_resampler *resampler;
73 struct kvm *kvm;
74 struct kvm_kernel_irqfd *irqfd;
75 int idx;
76
77 resampler = container_of(kian,
78 struct kvm_kernel_irqfd_resampler, notifier);
79 kvm = resampler->kvm;
80
81 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
82 resampler->notifier.gsi, 0, false);
83
84 idx = srcu_read_lock(&kvm->irq_srcu);
85
86 list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link)
87 eventfd_signal(irqfd->resamplefd, 1);
88
89 srcu_read_unlock(&kvm->irq_srcu, idx);
90}
91
92static void
93irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
94{
95 struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
96 struct kvm *kvm = resampler->kvm;
97
98 mutex_lock(&kvm->irqfds.resampler_lock);
99
100 list_del_rcu(&irqfd->resampler_link);
101 synchronize_srcu(&kvm->irq_srcu);
102
103 if (list_empty(&resampler->list)) {
104 list_del(&resampler->link);
105 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
106 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
107 resampler->notifier.gsi, 0, false);
108 kfree(resampler);
109 }
110
111 mutex_unlock(&kvm->irqfds.resampler_lock);
112}
113
114/*
115 * Race-free decouple logic (ordering is critical)
116 */
117static void
118irqfd_shutdown(struct work_struct *work)
119{
120 struct kvm_kernel_irqfd *irqfd =
121 container_of(work, struct kvm_kernel_irqfd, shutdown);
122 u64 cnt;
123
124 /*
125 * Synchronize with the wait-queue and unhook ourselves to prevent
126 * further events.
127 */
128 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
129
130 /*
131 * We know no new events will be scheduled at this point, so block
132 * until all previously outstanding events have completed
133 */
134 flush_work(&irqfd->inject);
135
136 if (irqfd->resampler) {
137 irqfd_resampler_shutdown(irqfd);
138 eventfd_ctx_put(irqfd->resamplefd);
139 }
140
141 /*
142 * It is now safe to release the object's resources
143 */
144#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
145 irq_bypass_unregister_consumer(&irqfd->consumer);
146#endif
147 eventfd_ctx_put(irqfd->eventfd);
148 kfree(irqfd);
149}
150
151
152/* assumes kvm->irqfds.lock is held */
153static bool
154irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
155{
156 return list_empty(&irqfd->list) ? false : true;
157}
158
159/*
160 * Mark the irqfd as inactive and schedule it for removal
161 *
162 * assumes kvm->irqfds.lock is held
163 */
164static void
165irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
166{
167 BUG_ON(!irqfd_is_active(irqfd));
168
169 list_del_init(&irqfd->list);
170
171 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
172}
173
174int __attribute__((weak)) kvm_arch_set_irq_inatomic(
175 struct kvm_kernel_irq_routing_entry *irq,
176 struct kvm *kvm, int irq_source_id,
177 int level,
178 bool line_status)
179{
180 return -EWOULDBLOCK;
181}
182
183/*
184 * Called with wqh->lock held and interrupts disabled
185 */
186static int
187irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
188{
189 struct kvm_kernel_irqfd *irqfd =
190 container_of(wait, struct kvm_kernel_irqfd, wait);
191 unsigned long flags = (unsigned long)key;
192 struct kvm_kernel_irq_routing_entry irq;
193 struct kvm *kvm = irqfd->kvm;
194 unsigned seq;
195 int idx;
196
197 if (flags & POLLIN) {
198 idx = srcu_read_lock(&kvm->irq_srcu);
199 do {
200 seq = read_seqcount_begin(&irqfd->irq_entry_sc);
201 irq = irqfd->irq_entry;
202 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
203 /* An event has been signaled, inject an interrupt */
204 if (kvm_arch_set_irq_inatomic(&irq, kvm,
205 KVM_USERSPACE_IRQ_SOURCE_ID, 1,
206 false) == -EWOULDBLOCK)
207 schedule_work(&irqfd->inject);
208 srcu_read_unlock(&kvm->irq_srcu, idx);
209 }
210
211 if (flags & POLLHUP) {
212 /* The eventfd is closing, detach from KVM */
213 unsigned long flags;
214
215 spin_lock_irqsave(&kvm->irqfds.lock, flags);
216
217 /*
218 * We must check if someone deactivated the irqfd before
219 * we could acquire the irqfds.lock since the item is
220 * deactivated from the KVM side before it is unhooked from
221 * the wait-queue. If it is already deactivated, we can
222 * simply return knowing the other side will cleanup for us.
223 * We cannot race against the irqfd going away since the
224 * other side is required to acquire wqh->lock, which we hold
225 */
226 if (irqfd_is_active(irqfd))
227 irqfd_deactivate(irqfd);
228
229 spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
230 }
231
232 return 0;
233}
234
235static void
236irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
237 poll_table *pt)
238{
239 struct kvm_kernel_irqfd *irqfd =
240 container_of(pt, struct kvm_kernel_irqfd, pt);
241 add_wait_queue(wqh, &irqfd->wait);
242}
243
244/* Must be called under irqfds.lock */
245static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
246{
247 struct kvm_kernel_irq_routing_entry *e;
248 struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
249 int n_entries;
250
251 n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
252
253 write_seqcount_begin(&irqfd->irq_entry_sc);
254
255 e = entries;
256 if (n_entries == 1)
257 irqfd->irq_entry = *e;
258 else
259 irqfd->irq_entry.type = 0;
260
261 write_seqcount_end(&irqfd->irq_entry_sc);
262}
263
264#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
265void __attribute__((weak)) kvm_arch_irq_bypass_stop(
266 struct irq_bypass_consumer *cons)
267{
268}
269
270void __attribute__((weak)) kvm_arch_irq_bypass_start(
271 struct irq_bypass_consumer *cons)
272{
273}
274
275int __attribute__((weak)) kvm_arch_update_irqfd_routing(
276 struct kvm *kvm, unsigned int host_irq,
277 uint32_t guest_irq, bool set)
278{
279 return 0;
280}
281#endif
282
283static int
284kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
285{
286 struct kvm_kernel_irqfd *irqfd, *tmp;
287 struct fd f;
288 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
289 int ret;
290 unsigned int events;
291 int idx;
292
293 if (!kvm_arch_intc_initialized(kvm))
294 return -EAGAIN;
295
296 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
297 if (!irqfd)
298 return -ENOMEM;
299
300 irqfd->kvm = kvm;
301 irqfd->gsi = args->gsi;
302 INIT_LIST_HEAD(&irqfd->list);
303 INIT_WORK(&irqfd->inject, irqfd_inject);
304 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
305 seqcount_init(&irqfd->irq_entry_sc);
306
307 f = fdget(args->fd);
308 if (!f.file) {
309 ret = -EBADF;
310 goto out;
311 }
312
313 eventfd = eventfd_ctx_fileget(f.file);
314 if (IS_ERR(eventfd)) {
315 ret = PTR_ERR(eventfd);
316 goto fail;
317 }
318
319 irqfd->eventfd = eventfd;
320
321 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
322 struct kvm_kernel_irqfd_resampler *resampler;
323
324 resamplefd = eventfd_ctx_fdget(args->resamplefd);
325 if (IS_ERR(resamplefd)) {
326 ret = PTR_ERR(resamplefd);
327 goto fail;
328 }
329
330 irqfd->resamplefd = resamplefd;
331 INIT_LIST_HEAD(&irqfd->resampler_link);
332
333 mutex_lock(&kvm->irqfds.resampler_lock);
334
335 list_for_each_entry(resampler,
336 &kvm->irqfds.resampler_list, link) {
337 if (resampler->notifier.gsi == irqfd->gsi) {
338 irqfd->resampler = resampler;
339 break;
340 }
341 }
342
343 if (!irqfd->resampler) {
344 resampler = kzalloc(sizeof(*resampler), GFP_KERNEL);
345 if (!resampler) {
346 ret = -ENOMEM;
347 mutex_unlock(&kvm->irqfds.resampler_lock);
348 goto fail;
349 }
350
351 resampler->kvm = kvm;
352 INIT_LIST_HEAD(&resampler->list);
353 resampler->notifier.gsi = irqfd->gsi;
354 resampler->notifier.irq_acked = irqfd_resampler_ack;
355 INIT_LIST_HEAD(&resampler->link);
356
357 list_add(&resampler->link, &kvm->irqfds.resampler_list);
358 kvm_register_irq_ack_notifier(kvm,
359 &resampler->notifier);
360 irqfd->resampler = resampler;
361 }
362
363 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
364 synchronize_srcu(&kvm->irq_srcu);
365
366 mutex_unlock(&kvm->irqfds.resampler_lock);
367 }
368
369 /*
370 * Install our own custom wake-up handling so we are notified via
371 * a callback whenever someone signals the underlying eventfd
372 */
373 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
374 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
375
376 spin_lock_irq(&kvm->irqfds.lock);
377
378 ret = 0;
379 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
380 if (irqfd->eventfd != tmp->eventfd)
381 continue;
382 /* This fd is used for another irq already. */
383 ret = -EBUSY;
384 spin_unlock_irq(&kvm->irqfds.lock);
385 goto fail;
386 }
387
388 idx = srcu_read_lock(&kvm->irq_srcu);
389 irqfd_update(kvm, irqfd);
390 srcu_read_unlock(&kvm->irq_srcu, idx);
391
392 list_add_tail(&irqfd->list, &kvm->irqfds.items);
393
394 spin_unlock_irq(&kvm->irqfds.lock);
395
396 /*
397 * Check if there was an event already pending on the eventfd
398 * before we registered, and trigger it as if we didn't miss it.
399 */
400 events = f.file->f_op->poll(f.file, &irqfd->pt);
401
402 if (events & POLLIN)
403 schedule_work(&irqfd->inject);
404
405 /*
406 * do not drop the file until the irqfd is fully initialized, otherwise
407 * we might race against the POLLHUP
408 */
409 fdput(f);
410#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
411 irqfd->consumer.token = (void *)irqfd->eventfd;
412 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
413 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
414 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
415 irqfd->consumer.start = kvm_arch_irq_bypass_start;
416 ret = irq_bypass_register_consumer(&irqfd->consumer);
417 if (ret)
418 pr_info("irq bypass consumer (token %p) registration fails: %d\n",
419 irqfd->consumer.token, ret);
420#endif
421
422 return 0;
423
424fail:
425 if (irqfd->resampler)
426 irqfd_resampler_shutdown(irqfd);
427
428 if (resamplefd && !IS_ERR(resamplefd))
429 eventfd_ctx_put(resamplefd);
430
431 if (eventfd && !IS_ERR(eventfd))
432 eventfd_ctx_put(eventfd);
433
434 fdput(f);
435
436out:
437 kfree(irqfd);
438 return ret;
439}
440
441bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
442{
443 struct kvm_irq_ack_notifier *kian;
444 int gsi, idx;
445
446 idx = srcu_read_lock(&kvm->irq_srcu);
447 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
448 if (gsi != -1)
449 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
450 link)
451 if (kian->gsi == gsi) {
452 srcu_read_unlock(&kvm->irq_srcu, idx);
453 return true;
454 }
455
456 srcu_read_unlock(&kvm->irq_srcu, idx);
457
458 return false;
459}
460EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
461
462void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
463{
464 struct kvm_irq_ack_notifier *kian;
465
466 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
467 link)
468 if (kian->gsi == gsi)
469 kian->irq_acked(kian);
470}
471
472void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
473{
474 int gsi, idx;
475
476 trace_kvm_ack_irq(irqchip, pin);
477
478 idx = srcu_read_lock(&kvm->irq_srcu);
479 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
480 if (gsi != -1)
481 kvm_notify_acked_gsi(kvm, gsi);
482 srcu_read_unlock(&kvm->irq_srcu, idx);
483}
484
485void kvm_register_irq_ack_notifier(struct kvm *kvm,
486 struct kvm_irq_ack_notifier *kian)
487{
488 mutex_lock(&kvm->irq_lock);
489 hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
490 mutex_unlock(&kvm->irq_lock);
491 kvm_vcpu_request_scan_ioapic(kvm);
492}
493
494void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
495 struct kvm_irq_ack_notifier *kian)
496{
497 mutex_lock(&kvm->irq_lock);
498 hlist_del_init_rcu(&kian->link);
499 mutex_unlock(&kvm->irq_lock);
500 synchronize_srcu(&kvm->irq_srcu);
501 kvm_vcpu_request_scan_ioapic(kvm);
502}
503#endif
504
505void
506kvm_eventfd_init(struct kvm *kvm)
507{
508#ifdef CONFIG_HAVE_KVM_IRQFD
509 spin_lock_init(&kvm->irqfds.lock);
510 INIT_LIST_HEAD(&kvm->irqfds.items);
511 INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
512 mutex_init(&kvm->irqfds.resampler_lock);
513#endif
514 INIT_LIST_HEAD(&kvm->ioeventfds);
515}
516
517#ifdef CONFIG_HAVE_KVM_IRQFD
518/*
519 * shutdown any irqfd's that match fd+gsi
520 */
521static int
522kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
523{
524 struct kvm_kernel_irqfd *irqfd, *tmp;
525 struct eventfd_ctx *eventfd;
526
527 eventfd = eventfd_ctx_fdget(args->fd);
528 if (IS_ERR(eventfd))
529 return PTR_ERR(eventfd);
530
531 spin_lock_irq(&kvm->irqfds.lock);
532
533 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
534 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
535 /*
536 * This clearing of irq_entry.type is needed for when
537 * another thread calls kvm_irq_routing_update before
538 * we flush workqueue below (we synchronize with
539 * kvm_irq_routing_update using irqfds.lock).
540 */
541 write_seqcount_begin(&irqfd->irq_entry_sc);
542 irqfd->irq_entry.type = 0;
543 write_seqcount_end(&irqfd->irq_entry_sc);
544 irqfd_deactivate(irqfd);
545 }
546 }
547
548 spin_unlock_irq(&kvm->irqfds.lock);
549 eventfd_ctx_put(eventfd);
550
551 /*
552 * Block until we know all outstanding shutdown jobs have completed
553 * so that we guarantee there will not be any more interrupts on this
554 * gsi once this deassign function returns.
555 */
556 flush_workqueue(irqfd_cleanup_wq);
557
558 return 0;
559}
560
561int
562kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
563{
564 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
565 return -EINVAL;
566
567 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
568 return kvm_irqfd_deassign(kvm, args);
569
570 return kvm_irqfd_assign(kvm, args);
571}
572
573/*
574 * This function is called as the kvm VM fd is being released. Shutdown all
575 * irqfds that still remain open
576 */
577void
578kvm_irqfd_release(struct kvm *kvm)
579{
580 struct kvm_kernel_irqfd *irqfd, *tmp;
581
582 spin_lock_irq(&kvm->irqfds.lock);
583
584 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
585 irqfd_deactivate(irqfd);
586
587 spin_unlock_irq(&kvm->irqfds.lock);
588
589 /*
590 * Block until we know all outstanding shutdown jobs have completed
591 * since we do not take a kvm* reference.
592 */
593 flush_workqueue(irqfd_cleanup_wq);
594
595}
596
597/*
598 * Take note of a change in irq routing.
599 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
600 */
601void kvm_irq_routing_update(struct kvm *kvm)
602{
603 struct kvm_kernel_irqfd *irqfd;
604
605 spin_lock_irq(&kvm->irqfds.lock);
606
607 list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
608 irqfd_update(kvm, irqfd);
609
610#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
611 if (irqfd->producer) {
612 int ret = kvm_arch_update_irqfd_routing(
613 irqfd->kvm, irqfd->producer->irq,
614 irqfd->gsi, 1);
615 WARN_ON(ret);
616 }
617#endif
618 }
619
620 spin_unlock_irq(&kvm->irqfds.lock);
621}
622
623/*
624 * create a host-wide workqueue for issuing deferred shutdown requests
625 * aggregated from all vm* instances. We need our own isolated single-thread
626 * queue to prevent deadlock against flushing the normal work-queue.
627 */
628int kvm_irqfd_init(void)
629{
630 irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
631 if (!irqfd_cleanup_wq)
632 return -ENOMEM;
633
634 return 0;
635}
636
637void kvm_irqfd_exit(void)
638{
639 destroy_workqueue(irqfd_cleanup_wq);
640}
641#endif
642
643/*
644 * --------------------------------------------------------------------
645 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
646 *
647 * userspace can register a PIO/MMIO address with an eventfd for receiving
648 * notification when the memory has been touched.
649 * --------------------------------------------------------------------
650 */
651
652struct _ioeventfd {
653 struct list_head list;
654 u64 addr;
655 int length;
656 struct eventfd_ctx *eventfd;
657 u64 datamatch;
658 struct kvm_io_device dev;
659 u8 bus_idx;
660 bool wildcard;
661};
662
663static inline struct _ioeventfd *
664to_ioeventfd(struct kvm_io_device *dev)
665{
666 return container_of(dev, struct _ioeventfd, dev);
667}
668
669static void
670ioeventfd_release(struct _ioeventfd *p)
671{
672 eventfd_ctx_put(p->eventfd);
673 list_del(&p->list);
674 kfree(p);
675}
676
677static bool
678ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
679{
680 u64 _val;
681
682 if (addr != p->addr)
683 /* address must be precise for a hit */
684 return false;
685
686 if (!p->length)
687 /* length = 0 means only look at the address, so always a hit */
688 return true;
689
690 if (len != p->length)
691 /* address-range must be precise for a hit */
692 return false;
693
694 if (p->wildcard)
695 /* all else equal, wildcard is always a hit */
696 return true;
697
698 /* otherwise, we have to actually compare the data */
699
700 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
701
702 switch (len) {
703 case 1:
704 _val = *(u8 *)val;
705 break;
706 case 2:
707 _val = *(u16 *)val;
708 break;
709 case 4:
710 _val = *(u32 *)val;
711 break;
712 case 8:
713 _val = *(u64 *)val;
714 break;
715 default:
716 return false;
717 }
718
719 return _val == p->datamatch ? true : false;
720}
721
722/* MMIO/PIO writes trigger an event if the addr/val match */
723static int
724ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
725 int len, const void *val)
726{
727 struct _ioeventfd *p = to_ioeventfd(this);
728
729 if (!ioeventfd_in_range(p, addr, len, val))
730 return -EOPNOTSUPP;
731
732 eventfd_signal(p->eventfd, 1);
733 return 0;
734}
735
736/*
737 * This function is called as KVM is completely shutting down. We do not
738 * need to worry about locking just nuke anything we have as quickly as possible
739 */
740static void
741ioeventfd_destructor(struct kvm_io_device *this)
742{
743 struct _ioeventfd *p = to_ioeventfd(this);
744
745 ioeventfd_release(p);
746}
747
748static const struct kvm_io_device_ops ioeventfd_ops = {
749 .write = ioeventfd_write,
750 .destructor = ioeventfd_destructor,
751};
752
753/* assumes kvm->slots_lock held */
754static bool
755ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
756{
757 struct _ioeventfd *_p;
758
759 list_for_each_entry(_p, &kvm->ioeventfds, list)
760 if (_p->bus_idx == p->bus_idx &&
761 _p->addr == p->addr &&
762 (!_p->length || !p->length ||
763 (_p->length == p->length &&
764 (_p->wildcard || p->wildcard ||
765 _p->datamatch == p->datamatch))))
766 return true;
767
768 return false;
769}
770
771static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
772{
773 if (flags & KVM_IOEVENTFD_FLAG_PIO)
774 return KVM_PIO_BUS;
775 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
776 return KVM_VIRTIO_CCW_NOTIFY_BUS;
777 return KVM_MMIO_BUS;
778}
779
780static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
781 enum kvm_bus bus_idx,
782 struct kvm_ioeventfd *args)
783{
784
785 struct eventfd_ctx *eventfd;
786 struct _ioeventfd *p;
787 int ret;
788
789 eventfd = eventfd_ctx_fdget(args->fd);
790 if (IS_ERR(eventfd))
791 return PTR_ERR(eventfd);
792
793 p = kzalloc(sizeof(*p), GFP_KERNEL);
794 if (!p) {
795 ret = -ENOMEM;
796 goto fail;
797 }
798
799 INIT_LIST_HEAD(&p->list);
800 p->addr = args->addr;
801 p->bus_idx = bus_idx;
802 p->length = args->len;
803 p->eventfd = eventfd;
804
805 /* The datamatch feature is optional, otherwise this is a wildcard */
806 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
807 p->datamatch = args->datamatch;
808 else
809 p->wildcard = true;
810
811 mutex_lock(&kvm->slots_lock);
812
813 /* Verify that there isn't a match already */
814 if (ioeventfd_check_collision(kvm, p)) {
815 ret = -EEXIST;
816 goto unlock_fail;
817 }
818
819 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
820
821 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
822 &p->dev);
823 if (ret < 0)
824 goto unlock_fail;
825
826 kvm->buses[bus_idx]->ioeventfd_count++;
827 list_add_tail(&p->list, &kvm->ioeventfds);
828
829 mutex_unlock(&kvm->slots_lock);
830
831 return 0;
832
833unlock_fail:
834 mutex_unlock(&kvm->slots_lock);
835
836fail:
837 kfree(p);
838 eventfd_ctx_put(eventfd);
839
840 return ret;
841}
842
843static int
844kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
845 struct kvm_ioeventfd *args)
846{
847 struct _ioeventfd *p, *tmp;
848 struct eventfd_ctx *eventfd;
849 int ret = -ENOENT;
850
851 eventfd = eventfd_ctx_fdget(args->fd);
852 if (IS_ERR(eventfd))
853 return PTR_ERR(eventfd);
854
855 mutex_lock(&kvm->slots_lock);
856
857 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
858 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
859
860 if (p->bus_idx != bus_idx ||
861 p->eventfd != eventfd ||
862 p->addr != args->addr ||
863 p->length != args->len ||
864 p->wildcard != wildcard)
865 continue;
866
867 if (!p->wildcard && p->datamatch != args->datamatch)
868 continue;
869
870 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
871 kvm->buses[bus_idx]->ioeventfd_count--;
872 ioeventfd_release(p);
873 ret = 0;
874 break;
875 }
876
877 mutex_unlock(&kvm->slots_lock);
878
879 eventfd_ctx_put(eventfd);
880
881 return ret;
882}
883
884static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
885{
886 enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
887 int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
888
889 if (!args->len && bus_idx == KVM_MMIO_BUS)
890 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
891
892 return ret;
893}
894
895static int
896kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
897{
898 enum kvm_bus bus_idx;
899 int ret;
900
901 bus_idx = ioeventfd_bus_from_flags(args->flags);
902 /* must be natural-word sized, or 0 to ignore length */
903 switch (args->len) {
904 case 0:
905 case 1:
906 case 2:
907 case 4:
908 case 8:
909 break;
910 default:
911 return -EINVAL;
912 }
913
914 /* check for range overflow */
915 if (args->addr + args->len < args->addr)
916 return -EINVAL;
917
918 /* check for extra flags that we don't understand */
919 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
920 return -EINVAL;
921
922 /* ioeventfd with no length can't be combined with DATAMATCH */
923 if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
924 return -EINVAL;
925
926 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
927 if (ret)
928 goto fail;
929
930 /* When length is ignored, MMIO is also put on a separate bus, for
931 * faster lookups.
932 */
933 if (!args->len && bus_idx == KVM_MMIO_BUS) {
934 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
935 if (ret < 0)
936 goto fast_fail;
937 }
938
939 return 0;
940
941fast_fail:
942 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
943fail:
944 return ret;
945}
946
947int
948kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
949{
950 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
951 return kvm_deassign_ioeventfd(kvm, args);
952
953 return kvm_assign_ioeventfd(kvm, args);
954}