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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kvm eventfd support - use eventfd objects to signal various KVM events
4 *
5 * Copyright 2009 Novell. All Rights Reserved.
6 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
7 *
8 * Author:
9 * Gregory Haskins <ghaskins@novell.com>
10 */
11
12#include <linux/kvm_host.h>
13#include <linux/kvm.h>
14#include <linux/kvm_irqfd.h>
15#include <linux/workqueue.h>
16#include <linux/syscalls.h>
17#include <linux/wait.h>
18#include <linux/poll.h>
19#include <linux/file.h>
20#include <linux/list.h>
21#include <linux/eventfd.h>
22#include <linux/kernel.h>
23#include <linux/srcu.h>
24#include <linux/slab.h>
25#include <linux/seqlock.h>
26#include <linux/irqbypass.h>
27#include <trace/events/kvm.h>
28
29#include <kvm/iodev.h>
30
31#ifdef CONFIG_HAVE_KVM_IRQCHIP
32
33static struct workqueue_struct *irqfd_cleanup_wq;
34
35bool __attribute__((weak))
36kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
37{
38 return true;
39}
40
41static void
42irqfd_inject(struct work_struct *work)
43{
44 struct kvm_kernel_irqfd *irqfd =
45 container_of(work, struct kvm_kernel_irqfd, inject);
46 struct kvm *kvm = irqfd->kvm;
47
48 if (!irqfd->resampler) {
49 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
50 false);
51 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
52 false);
53 } else
54 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
55 irqfd->gsi, 1, false);
56}
57
58static void irqfd_resampler_notify(struct kvm_kernel_irqfd_resampler *resampler)
59{
60 struct kvm_kernel_irqfd *irqfd;
61
62 list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link,
63 srcu_read_lock_held(&resampler->kvm->irq_srcu))
64 eventfd_signal(irqfd->resamplefd);
65}
66
67/*
68 * Since resampler irqfds share an IRQ source ID, we de-assert once
69 * then notify all of the resampler irqfds using this GSI. We can't
70 * do multiple de-asserts or we risk racing with incoming re-asserts.
71 */
72static void
73irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
74{
75 struct kvm_kernel_irqfd_resampler *resampler;
76 struct kvm *kvm;
77 int idx;
78
79 resampler = container_of(kian,
80 struct kvm_kernel_irqfd_resampler, notifier);
81 kvm = resampler->kvm;
82
83 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
84 resampler->notifier.gsi, 0, false);
85
86 idx = srcu_read_lock(&kvm->irq_srcu);
87 irqfd_resampler_notify(resampler);
88 srcu_read_unlock(&kvm->irq_srcu, idx);
89}
90
91static void
92irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
93{
94 struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
95 struct kvm *kvm = resampler->kvm;
96
97 mutex_lock(&kvm->irqfds.resampler_lock);
98
99 list_del_rcu(&irqfd->resampler_link);
100
101 if (list_empty(&resampler->list)) {
102 list_del_rcu(&resampler->link);
103 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
104 /*
105 * synchronize_srcu_expedited(&kvm->irq_srcu) already called
106 * in kvm_unregister_irq_ack_notifier().
107 */
108 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
109 resampler->notifier.gsi, 0, false);
110 kfree(resampler);
111 } else {
112 synchronize_srcu_expedited(&kvm->irq_srcu);
113 }
114
115 mutex_unlock(&kvm->irqfds.resampler_lock);
116}
117
118/*
119 * Race-free decouple logic (ordering is critical)
120 */
121static void
122irqfd_shutdown(struct work_struct *work)
123{
124 struct kvm_kernel_irqfd *irqfd =
125 container_of(work, struct kvm_kernel_irqfd, shutdown);
126 struct kvm *kvm = irqfd->kvm;
127 u64 cnt;
128
129 /* Make sure irqfd has been initialized in assign path. */
130 synchronize_srcu_expedited(&kvm->irq_srcu);
131
132 /*
133 * Synchronize with the wait-queue and unhook ourselves to prevent
134 * further events.
135 */
136 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
137
138 /*
139 * We know no new events will be scheduled at this point, so block
140 * until all previously outstanding events have completed
141 */
142 flush_work(&irqfd->inject);
143
144 if (irqfd->resampler) {
145 irqfd_resampler_shutdown(irqfd);
146 eventfd_ctx_put(irqfd->resamplefd);
147 }
148
149 /*
150 * It is now safe to release the object's resources
151 */
152#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
153 irq_bypass_unregister_consumer(&irqfd->consumer);
154#endif
155 eventfd_ctx_put(irqfd->eventfd);
156 kfree(irqfd);
157}
158
159
160/* assumes kvm->irqfds.lock is held */
161static bool
162irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
163{
164 return list_empty(&irqfd->list) ? false : true;
165}
166
167/*
168 * Mark the irqfd as inactive and schedule it for removal
169 *
170 * assumes kvm->irqfds.lock is held
171 */
172static void
173irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
174{
175 BUG_ON(!irqfd_is_active(irqfd));
176
177 list_del_init(&irqfd->list);
178
179 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
180}
181
182int __attribute__((weak)) kvm_arch_set_irq_inatomic(
183 struct kvm_kernel_irq_routing_entry *irq,
184 struct kvm *kvm, int irq_source_id,
185 int level,
186 bool line_status)
187{
188 return -EWOULDBLOCK;
189}
190
191/*
192 * Called with wqh->lock held and interrupts disabled
193 */
194static int
195irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
196{
197 struct kvm_kernel_irqfd *irqfd =
198 container_of(wait, struct kvm_kernel_irqfd, wait);
199 __poll_t flags = key_to_poll(key);
200 struct kvm_kernel_irq_routing_entry irq;
201 struct kvm *kvm = irqfd->kvm;
202 unsigned seq;
203 int idx;
204 int ret = 0;
205
206 if (flags & EPOLLIN) {
207 u64 cnt;
208 eventfd_ctx_do_read(irqfd->eventfd, &cnt);
209
210 idx = srcu_read_lock(&kvm->irq_srcu);
211 do {
212 seq = read_seqcount_begin(&irqfd->irq_entry_sc);
213 irq = irqfd->irq_entry;
214 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
215 /* An event has been signaled, inject an interrupt */
216 if (kvm_arch_set_irq_inatomic(&irq, kvm,
217 KVM_USERSPACE_IRQ_SOURCE_ID, 1,
218 false) == -EWOULDBLOCK)
219 schedule_work(&irqfd->inject);
220 srcu_read_unlock(&kvm->irq_srcu, idx);
221 ret = 1;
222 }
223
224 if (flags & EPOLLHUP) {
225 /* The eventfd is closing, detach from KVM */
226 unsigned long iflags;
227
228 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
229
230 /*
231 * We must check if someone deactivated the irqfd before
232 * we could acquire the irqfds.lock since the item is
233 * deactivated from the KVM side before it is unhooked from
234 * the wait-queue. If it is already deactivated, we can
235 * simply return knowing the other side will cleanup for us.
236 * We cannot race against the irqfd going away since the
237 * other side is required to acquire wqh->lock, which we hold
238 */
239 if (irqfd_is_active(irqfd))
240 irqfd_deactivate(irqfd);
241
242 spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
243 }
244
245 return ret;
246}
247
248static void
249irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
250 poll_table *pt)
251{
252 struct kvm_kernel_irqfd *irqfd =
253 container_of(pt, struct kvm_kernel_irqfd, pt);
254 add_wait_queue_priority(wqh, &irqfd->wait);
255}
256
257/* Must be called under irqfds.lock */
258static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
259{
260 struct kvm_kernel_irq_routing_entry *e;
261 struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
262 int n_entries;
263
264 n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
265
266 write_seqcount_begin(&irqfd->irq_entry_sc);
267
268 e = entries;
269 if (n_entries == 1)
270 irqfd->irq_entry = *e;
271 else
272 irqfd->irq_entry.type = 0;
273
274 write_seqcount_end(&irqfd->irq_entry_sc);
275}
276
277#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
278void __attribute__((weak)) kvm_arch_irq_bypass_stop(
279 struct irq_bypass_consumer *cons)
280{
281}
282
283void __attribute__((weak)) kvm_arch_irq_bypass_start(
284 struct irq_bypass_consumer *cons)
285{
286}
287
288int __attribute__((weak)) kvm_arch_update_irqfd_routing(
289 struct kvm *kvm, unsigned int host_irq,
290 uint32_t guest_irq, bool set)
291{
292 return 0;
293}
294
295bool __attribute__((weak)) kvm_arch_irqfd_route_changed(
296 struct kvm_kernel_irq_routing_entry *old,
297 struct kvm_kernel_irq_routing_entry *new)
298{
299 return true;
300}
301#endif
302
303static int
304kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
305{
306 struct kvm_kernel_irqfd *irqfd, *tmp;
307 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
308 int ret;
309 __poll_t events;
310 int idx;
311
312 if (!kvm_arch_intc_initialized(kvm))
313 return -EAGAIN;
314
315 if (!kvm_arch_irqfd_allowed(kvm, args))
316 return -EINVAL;
317
318 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
319 if (!irqfd)
320 return -ENOMEM;
321
322 irqfd->kvm = kvm;
323 irqfd->gsi = args->gsi;
324 INIT_LIST_HEAD(&irqfd->list);
325 INIT_WORK(&irqfd->inject, irqfd_inject);
326 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
327 seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
328
329 CLASS(fd, f)(args->fd);
330 if (fd_empty(f)) {
331 ret = -EBADF;
332 goto out;
333 }
334
335 eventfd = eventfd_ctx_fileget(fd_file(f));
336 if (IS_ERR(eventfd)) {
337 ret = PTR_ERR(eventfd);
338 goto out;
339 }
340
341 irqfd->eventfd = eventfd;
342
343 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
344 struct kvm_kernel_irqfd_resampler *resampler;
345
346 resamplefd = eventfd_ctx_fdget(args->resamplefd);
347 if (IS_ERR(resamplefd)) {
348 ret = PTR_ERR(resamplefd);
349 goto fail;
350 }
351
352 irqfd->resamplefd = resamplefd;
353 INIT_LIST_HEAD(&irqfd->resampler_link);
354
355 mutex_lock(&kvm->irqfds.resampler_lock);
356
357 list_for_each_entry(resampler,
358 &kvm->irqfds.resampler_list, link) {
359 if (resampler->notifier.gsi == irqfd->gsi) {
360 irqfd->resampler = resampler;
361 break;
362 }
363 }
364
365 if (!irqfd->resampler) {
366 resampler = kzalloc(sizeof(*resampler),
367 GFP_KERNEL_ACCOUNT);
368 if (!resampler) {
369 ret = -ENOMEM;
370 mutex_unlock(&kvm->irqfds.resampler_lock);
371 goto fail;
372 }
373
374 resampler->kvm = kvm;
375 INIT_LIST_HEAD(&resampler->list);
376 resampler->notifier.gsi = irqfd->gsi;
377 resampler->notifier.irq_acked = irqfd_resampler_ack;
378 INIT_LIST_HEAD(&resampler->link);
379
380 list_add_rcu(&resampler->link, &kvm->irqfds.resampler_list);
381 kvm_register_irq_ack_notifier(kvm,
382 &resampler->notifier);
383 irqfd->resampler = resampler;
384 }
385
386 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
387 synchronize_srcu_expedited(&kvm->irq_srcu);
388
389 mutex_unlock(&kvm->irqfds.resampler_lock);
390 }
391
392 /*
393 * Install our own custom wake-up handling so we are notified via
394 * a callback whenever someone signals the underlying eventfd
395 */
396 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
397 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
398
399 spin_lock_irq(&kvm->irqfds.lock);
400
401 ret = 0;
402 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
403 if (irqfd->eventfd != tmp->eventfd)
404 continue;
405 /* This fd is used for another irq already. */
406 ret = -EBUSY;
407 spin_unlock_irq(&kvm->irqfds.lock);
408 goto fail;
409 }
410
411 idx = srcu_read_lock(&kvm->irq_srcu);
412 irqfd_update(kvm, irqfd);
413
414 list_add_tail(&irqfd->list, &kvm->irqfds.items);
415
416 spin_unlock_irq(&kvm->irqfds.lock);
417
418 /*
419 * Check if there was an event already pending on the eventfd
420 * before we registered, and trigger it as if we didn't miss it.
421 */
422 events = vfs_poll(fd_file(f), &irqfd->pt);
423
424 if (events & EPOLLIN)
425 schedule_work(&irqfd->inject);
426
427#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
428 if (kvm_arch_has_irq_bypass()) {
429 irqfd->consumer.token = (void *)irqfd->eventfd;
430 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
431 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
432 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
433 irqfd->consumer.start = kvm_arch_irq_bypass_start;
434 ret = irq_bypass_register_consumer(&irqfd->consumer);
435 if (ret)
436 pr_info("irq bypass consumer (token %p) registration fails: %d\n",
437 irqfd->consumer.token, ret);
438 }
439#endif
440
441 srcu_read_unlock(&kvm->irq_srcu, idx);
442 return 0;
443
444fail:
445 if (irqfd->resampler)
446 irqfd_resampler_shutdown(irqfd);
447
448 if (resamplefd && !IS_ERR(resamplefd))
449 eventfd_ctx_put(resamplefd);
450
451 if (eventfd && !IS_ERR(eventfd))
452 eventfd_ctx_put(eventfd);
453
454out:
455 kfree(irqfd);
456 return ret;
457}
458
459bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
460{
461 struct kvm_irq_ack_notifier *kian;
462 int gsi, idx;
463
464 idx = srcu_read_lock(&kvm->irq_srcu);
465 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
466 if (gsi != -1)
467 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
468 link, srcu_read_lock_held(&kvm->irq_srcu))
469 if (kian->gsi == gsi) {
470 srcu_read_unlock(&kvm->irq_srcu, idx);
471 return true;
472 }
473
474 srcu_read_unlock(&kvm->irq_srcu, idx);
475
476 return false;
477}
478EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
479
480void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
481{
482 struct kvm_irq_ack_notifier *kian;
483
484 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
485 link, srcu_read_lock_held(&kvm->irq_srcu))
486 if (kian->gsi == gsi)
487 kian->irq_acked(kian);
488}
489
490void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
491{
492 int gsi, idx;
493
494 trace_kvm_ack_irq(irqchip, pin);
495
496 idx = srcu_read_lock(&kvm->irq_srcu);
497 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
498 if (gsi != -1)
499 kvm_notify_acked_gsi(kvm, gsi);
500 srcu_read_unlock(&kvm->irq_srcu, idx);
501}
502
503void kvm_register_irq_ack_notifier(struct kvm *kvm,
504 struct kvm_irq_ack_notifier *kian)
505{
506 mutex_lock(&kvm->irq_lock);
507 hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
508 mutex_unlock(&kvm->irq_lock);
509 kvm_arch_post_irq_ack_notifier_list_update(kvm);
510}
511
512void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
513 struct kvm_irq_ack_notifier *kian)
514{
515 mutex_lock(&kvm->irq_lock);
516 hlist_del_init_rcu(&kian->link);
517 mutex_unlock(&kvm->irq_lock);
518 synchronize_srcu_expedited(&kvm->irq_srcu);
519 kvm_arch_post_irq_ack_notifier_list_update(kvm);
520}
521
522/*
523 * shutdown any irqfd's that match fd+gsi
524 */
525static int
526kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
527{
528 struct kvm_kernel_irqfd *irqfd, *tmp;
529 struct eventfd_ctx *eventfd;
530
531 eventfd = eventfd_ctx_fdget(args->fd);
532 if (IS_ERR(eventfd))
533 return PTR_ERR(eventfd);
534
535 spin_lock_irq(&kvm->irqfds.lock);
536
537 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
538 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
539 /*
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).
544 */
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);
549 }
550 }
551
552 spin_unlock_irq(&kvm->irqfds.lock);
553 eventfd_ctx_put(eventfd);
554
555 /*
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.
559 */
560 flush_workqueue(irqfd_cleanup_wq);
561
562 return 0;
563}
564
565int
566kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
567{
568 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
569 return -EINVAL;
570
571 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
572 return kvm_irqfd_deassign(kvm, args);
573
574 return kvm_irqfd_assign(kvm, args);
575}
576
577/*
578 * This function is called as the kvm VM fd is being released. Shutdown all
579 * irqfds that still remain open
580 */
581void
582kvm_irqfd_release(struct kvm *kvm)
583{
584 struct kvm_kernel_irqfd *irqfd, *tmp;
585
586 spin_lock_irq(&kvm->irqfds.lock);
587
588 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
589 irqfd_deactivate(irqfd);
590
591 spin_unlock_irq(&kvm->irqfds.lock);
592
593 /*
594 * Block until we know all outstanding shutdown jobs have completed
595 * since we do not take a kvm* reference.
596 */
597 flush_workqueue(irqfd_cleanup_wq);
598
599}
600
601/*
602 * Take note of a change in irq routing.
603 * Caller must invoke synchronize_srcu_expedited(&kvm->irq_srcu) afterwards.
604 */
605void kvm_irq_routing_update(struct kvm *kvm)
606{
607 struct kvm_kernel_irqfd *irqfd;
608
609 spin_lock_irq(&kvm->irqfds.lock);
610
611 list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
612#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
613 /* Under irqfds.lock, so can read irq_entry safely */
614 struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry;
615#endif
616
617 irqfd_update(kvm, irqfd);
618
619#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
620 if (irqfd->producer &&
621 kvm_arch_irqfd_route_changed(&old, &irqfd->irq_entry)) {
622 int ret = kvm_arch_update_irqfd_routing(
623 irqfd->kvm, irqfd->producer->irq,
624 irqfd->gsi, 1);
625 WARN_ON(ret);
626 }
627#endif
628 }
629
630 spin_unlock_irq(&kvm->irqfds.lock);
631}
632
633bool kvm_notify_irqfd_resampler(struct kvm *kvm,
634 unsigned int irqchip,
635 unsigned int pin)
636{
637 struct kvm_kernel_irqfd_resampler *resampler;
638 int gsi, idx;
639
640 idx = srcu_read_lock(&kvm->irq_srcu);
641 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
642 if (gsi != -1) {
643 list_for_each_entry_srcu(resampler,
644 &kvm->irqfds.resampler_list, link,
645 srcu_read_lock_held(&kvm->irq_srcu)) {
646 if (resampler->notifier.gsi == gsi) {
647 irqfd_resampler_notify(resampler);
648 srcu_read_unlock(&kvm->irq_srcu, idx);
649 return true;
650 }
651 }
652 }
653 srcu_read_unlock(&kvm->irq_srcu, idx);
654
655 return false;
656}
657
658/*
659 * create a host-wide workqueue for issuing deferred shutdown requests
660 * aggregated from all vm* instances. We need our own isolated
661 * queue to ease flushing work items when a VM exits.
662 */
663int kvm_irqfd_init(void)
664{
665 irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
666 if (!irqfd_cleanup_wq)
667 return -ENOMEM;
668
669 return 0;
670}
671
672void kvm_irqfd_exit(void)
673{
674 destroy_workqueue(irqfd_cleanup_wq);
675}
676#endif
677
678/*
679 * --------------------------------------------------------------------
680 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
681 *
682 * userspace can register a PIO/MMIO address with an eventfd for receiving
683 * notification when the memory has been touched.
684 * --------------------------------------------------------------------
685 */
686
687struct _ioeventfd {
688 struct list_head list;
689 u64 addr;
690 int length;
691 struct eventfd_ctx *eventfd;
692 u64 datamatch;
693 struct kvm_io_device dev;
694 u8 bus_idx;
695 bool wildcard;
696};
697
698static inline struct _ioeventfd *
699to_ioeventfd(struct kvm_io_device *dev)
700{
701 return container_of(dev, struct _ioeventfd, dev);
702}
703
704static void
705ioeventfd_release(struct _ioeventfd *p)
706{
707 eventfd_ctx_put(p->eventfd);
708 list_del(&p->list);
709 kfree(p);
710}
711
712static bool
713ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
714{
715 u64 _val;
716
717 if (addr != p->addr)
718 /* address must be precise for a hit */
719 return false;
720
721 if (!p->length)
722 /* length = 0 means only look at the address, so always a hit */
723 return true;
724
725 if (len != p->length)
726 /* address-range must be precise for a hit */
727 return false;
728
729 if (p->wildcard)
730 /* all else equal, wildcard is always a hit */
731 return true;
732
733 /* otherwise, we have to actually compare the data */
734
735 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
736
737 switch (len) {
738 case 1:
739 _val = *(u8 *)val;
740 break;
741 case 2:
742 _val = *(u16 *)val;
743 break;
744 case 4:
745 _val = *(u32 *)val;
746 break;
747 case 8:
748 _val = *(u64 *)val;
749 break;
750 default:
751 return false;
752 }
753
754 return _val == p->datamatch;
755}
756
757/* MMIO/PIO writes trigger an event if the addr/val match */
758static int
759ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
760 int len, const void *val)
761{
762 struct _ioeventfd *p = to_ioeventfd(this);
763
764 if (!ioeventfd_in_range(p, addr, len, val))
765 return -EOPNOTSUPP;
766
767 eventfd_signal(p->eventfd);
768 return 0;
769}
770
771/*
772 * This function is called as KVM is completely shutting down. We do not
773 * need to worry about locking just nuke anything we have as quickly as possible
774 */
775static void
776ioeventfd_destructor(struct kvm_io_device *this)
777{
778 struct _ioeventfd *p = to_ioeventfd(this);
779
780 ioeventfd_release(p);
781}
782
783static const struct kvm_io_device_ops ioeventfd_ops = {
784 .write = ioeventfd_write,
785 .destructor = ioeventfd_destructor,
786};
787
788/* assumes kvm->slots_lock held */
789static bool
790ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
791{
792 struct _ioeventfd *_p;
793
794 list_for_each_entry(_p, &kvm->ioeventfds, list)
795 if (_p->bus_idx == p->bus_idx &&
796 _p->addr == p->addr &&
797 (!_p->length || !p->length ||
798 (_p->length == p->length &&
799 (_p->wildcard || p->wildcard ||
800 _p->datamatch == p->datamatch))))
801 return true;
802
803 return false;
804}
805
806static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
807{
808 if (flags & KVM_IOEVENTFD_FLAG_PIO)
809 return KVM_PIO_BUS;
810 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
811 return KVM_VIRTIO_CCW_NOTIFY_BUS;
812 return KVM_MMIO_BUS;
813}
814
815static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
816 enum kvm_bus bus_idx,
817 struct kvm_ioeventfd *args)
818{
819
820 struct eventfd_ctx *eventfd;
821 struct _ioeventfd *p;
822 int ret;
823
824 eventfd = eventfd_ctx_fdget(args->fd);
825 if (IS_ERR(eventfd))
826 return PTR_ERR(eventfd);
827
828 p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
829 if (!p) {
830 ret = -ENOMEM;
831 goto fail;
832 }
833
834 INIT_LIST_HEAD(&p->list);
835 p->addr = args->addr;
836 p->bus_idx = bus_idx;
837 p->length = args->len;
838 p->eventfd = eventfd;
839
840 /* The datamatch feature is optional, otherwise this is a wildcard */
841 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
842 p->datamatch = args->datamatch;
843 else
844 p->wildcard = true;
845
846 mutex_lock(&kvm->slots_lock);
847
848 /* Verify that there isn't a match already */
849 if (ioeventfd_check_collision(kvm, p)) {
850 ret = -EEXIST;
851 goto unlock_fail;
852 }
853
854 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
855
856 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
857 &p->dev);
858 if (ret < 0)
859 goto unlock_fail;
860
861 kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
862 list_add_tail(&p->list, &kvm->ioeventfds);
863
864 mutex_unlock(&kvm->slots_lock);
865
866 return 0;
867
868unlock_fail:
869 mutex_unlock(&kvm->slots_lock);
870 kfree(p);
871
872fail:
873 eventfd_ctx_put(eventfd);
874
875 return ret;
876}
877
878static int
879kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
880 struct kvm_ioeventfd *args)
881{
882 struct _ioeventfd *p;
883 struct eventfd_ctx *eventfd;
884 struct kvm_io_bus *bus;
885 int ret = -ENOENT;
886 bool wildcard;
887
888 eventfd = eventfd_ctx_fdget(args->fd);
889 if (IS_ERR(eventfd))
890 return PTR_ERR(eventfd);
891
892 wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
893
894 mutex_lock(&kvm->slots_lock);
895
896 list_for_each_entry(p, &kvm->ioeventfds, list) {
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)
902 continue;
903
904 if (!p->wildcard && p->datamatch != args->datamatch)
905 continue;
906
907 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
908 bus = kvm_get_bus(kvm, bus_idx);
909 if (bus)
910 bus->ioeventfd_count--;
911 ret = 0;
912 break;
913 }
914
915 mutex_unlock(&kvm->slots_lock);
916
917 eventfd_ctx_put(eventfd);
918
919 return ret;
920}
921
922static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
923{
924 enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
925 int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
926
927 if (!args->len && bus_idx == KVM_MMIO_BUS)
928 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
929
930 return ret;
931}
932
933static int
934kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
935{
936 enum kvm_bus bus_idx;
937 int ret;
938
939 bus_idx = ioeventfd_bus_from_flags(args->flags);
940 /* must be natural-word sized, or 0 to ignore length */
941 switch (args->len) {
942 case 0:
943 case 1:
944 case 2:
945 case 4:
946 case 8:
947 break;
948 default:
949 return -EINVAL;
950 }
951
952 /* check for range overflow */
953 if (args->addr + args->len < args->addr)
954 return -EINVAL;
955
956 /* check for extra flags that we don't understand */
957 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
958 return -EINVAL;
959
960 /* ioeventfd with no length can't be combined with DATAMATCH */
961 if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
962 return -EINVAL;
963
964 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
965 if (ret)
966 goto fail;
967
968 /* When length is ignored, MMIO is also put on a separate bus, for
969 * faster lookups.
970 */
971 if (!args->len && bus_idx == KVM_MMIO_BUS) {
972 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
973 if (ret < 0)
974 goto fast_fail;
975 }
976
977 return 0;
978
979fast_fail:
980 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
981fail:
982 return ret;
983}
984
985int
986kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
987{
988 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
989 return kvm_deassign_ioeventfd(kvm, args);
990
991 return kvm_assign_ioeventfd(kvm, args);
992}
993
994void
995kvm_eventfd_init(struct kvm *kvm)
996{
997#ifdef CONFIG_HAVE_KVM_IRQCHIP
998 spin_lock_init(&kvm->irqfds.lock);
999 INIT_LIST_HEAD(&kvm->irqfds.items);
1000 INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
1001 mutex_init(&kvm->irqfds.resampler_lock);
1002#endif
1003 INIT_LIST_HEAD(&kvm->ioeventfds);
1004}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kvm eventfd support - use eventfd objects to signal various KVM events
4 *
5 * Copyright 2009 Novell. All Rights Reserved.
6 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
7 *
8 * Author:
9 * Gregory Haskins <ghaskins@novell.com>
10 */
11
12#include <linux/kvm_host.h>
13#include <linux/kvm.h>
14#include <linux/kvm_irqfd.h>
15#include <linux/workqueue.h>
16#include <linux/syscalls.h>
17#include <linux/wait.h>
18#include <linux/poll.h>
19#include <linux/file.h>
20#include <linux/list.h>
21#include <linux/eventfd.h>
22#include <linux/kernel.h>
23#include <linux/srcu.h>
24#include <linux/slab.h>
25#include <linux/seqlock.h>
26#include <linux/irqbypass.h>
27#include <trace/events/kvm.h>
28
29#include <kvm/iodev.h>
30
31#ifdef CONFIG_HAVE_KVM_IRQFD
32
33static struct workqueue_struct *irqfd_cleanup_wq;
34
35bool __attribute__((weak))
36kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
37{
38 return true;
39}
40
41static void
42irqfd_inject(struct work_struct *work)
43{
44 struct kvm_kernel_irqfd *irqfd =
45 container_of(work, struct kvm_kernel_irqfd, inject);
46 struct kvm *kvm = irqfd->kvm;
47
48 if (!irqfd->resampler) {
49 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
50 false);
51 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
52 false);
53 } else
54 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
55 irqfd->gsi, 1, false);
56}
57
58/*
59 * Since resampler irqfds share an IRQ source ID, we de-assert once
60 * then notify all of the resampler irqfds using this GSI. We can't
61 * do multiple de-asserts or we risk racing with incoming re-asserts.
62 */
63static void
64irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
65{
66 struct kvm_kernel_irqfd_resampler *resampler;
67 struct kvm *kvm;
68 struct kvm_kernel_irqfd *irqfd;
69 int idx;
70
71 resampler = container_of(kian,
72 struct kvm_kernel_irqfd_resampler, notifier);
73 kvm = resampler->kvm;
74
75 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
76 resampler->notifier.gsi, 0, false);
77
78 idx = srcu_read_lock(&kvm->irq_srcu);
79
80 list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link)
81 eventfd_signal(irqfd->resamplefd, 1);
82
83 srcu_read_unlock(&kvm->irq_srcu, idx);
84}
85
86static void
87irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
88{
89 struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
90 struct kvm *kvm = resampler->kvm;
91
92 mutex_lock(&kvm->irqfds.resampler_lock);
93
94 list_del_rcu(&irqfd->resampler_link);
95 synchronize_srcu(&kvm->irq_srcu);
96
97 if (list_empty(&resampler->list)) {
98 list_del(&resampler->link);
99 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
100 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
101 resampler->notifier.gsi, 0, false);
102 kfree(resampler);
103 }
104
105 mutex_unlock(&kvm->irqfds.resampler_lock);
106}
107
108/*
109 * Race-free decouple logic (ordering is critical)
110 */
111static void
112irqfd_shutdown(struct work_struct *work)
113{
114 struct kvm_kernel_irqfd *irqfd =
115 container_of(work, struct kvm_kernel_irqfd, shutdown);
116 struct kvm *kvm = irqfd->kvm;
117 u64 cnt;
118
119 /* Make sure irqfd has been initialized in assign path. */
120 synchronize_srcu(&kvm->irq_srcu);
121
122 /*
123 * Synchronize with the wait-queue and unhook ourselves to prevent
124 * further events.
125 */
126 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
127
128 /*
129 * We know no new events will be scheduled at this point, so block
130 * until all previously outstanding events have completed
131 */
132 flush_work(&irqfd->inject);
133
134 if (irqfd->resampler) {
135 irqfd_resampler_shutdown(irqfd);
136 eventfd_ctx_put(irqfd->resamplefd);
137 }
138
139 /*
140 * It is now safe to release the object's resources
141 */
142#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
143 irq_bypass_unregister_consumer(&irqfd->consumer);
144#endif
145 eventfd_ctx_put(irqfd->eventfd);
146 kfree(irqfd);
147}
148
149
150/* assumes kvm->irqfds.lock is held */
151static bool
152irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
153{
154 return list_empty(&irqfd->list) ? false : true;
155}
156
157/*
158 * Mark the irqfd as inactive and schedule it for removal
159 *
160 * assumes kvm->irqfds.lock is held
161 */
162static void
163irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
164{
165 BUG_ON(!irqfd_is_active(irqfd));
166
167 list_del_init(&irqfd->list);
168
169 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
170}
171
172int __attribute__((weak)) kvm_arch_set_irq_inatomic(
173 struct kvm_kernel_irq_routing_entry *irq,
174 struct kvm *kvm, int irq_source_id,
175 int level,
176 bool line_status)
177{
178 return -EWOULDBLOCK;
179}
180
181/*
182 * Called with wqh->lock held and interrupts disabled
183 */
184static int
185irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
186{
187 struct kvm_kernel_irqfd *irqfd =
188 container_of(wait, struct kvm_kernel_irqfd, wait);
189 __poll_t flags = key_to_poll(key);
190 struct kvm_kernel_irq_routing_entry irq;
191 struct kvm *kvm = irqfd->kvm;
192 unsigned seq;
193 int idx;
194 int ret = 0;
195
196 if (flags & EPOLLIN) {
197 u64 cnt;
198 eventfd_ctx_do_read(irqfd->eventfd, &cnt);
199
200 idx = srcu_read_lock(&kvm->irq_srcu);
201 do {
202 seq = read_seqcount_begin(&irqfd->irq_entry_sc);
203 irq = irqfd->irq_entry;
204 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
205 /* An event has been signaled, inject an interrupt */
206 if (kvm_arch_set_irq_inatomic(&irq, kvm,
207 KVM_USERSPACE_IRQ_SOURCE_ID, 1,
208 false) == -EWOULDBLOCK)
209 schedule_work(&irqfd->inject);
210 srcu_read_unlock(&kvm->irq_srcu, idx);
211 ret = 1;
212 }
213
214 if (flags & EPOLLHUP) {
215 /* The eventfd is closing, detach from KVM */
216 unsigned long iflags;
217
218 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
219
220 /*
221 * We must check if someone deactivated the irqfd before
222 * we could acquire the irqfds.lock since the item is
223 * deactivated from the KVM side before it is unhooked from
224 * the wait-queue. If it is already deactivated, we can
225 * simply return knowing the other side will cleanup for us.
226 * We cannot race against the irqfd going away since the
227 * other side is required to acquire wqh->lock, which we hold
228 */
229 if (irqfd_is_active(irqfd))
230 irqfd_deactivate(irqfd);
231
232 spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
233 }
234
235 return ret;
236}
237
238static void
239irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
240 poll_table *pt)
241{
242 struct kvm_kernel_irqfd *irqfd =
243 container_of(pt, struct kvm_kernel_irqfd, pt);
244 add_wait_queue_priority(wqh, &irqfd->wait);
245}
246
247/* Must be called under irqfds.lock */
248static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
249{
250 struct kvm_kernel_irq_routing_entry *e;
251 struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
252 int n_entries;
253
254 n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
255
256 write_seqcount_begin(&irqfd->irq_entry_sc);
257
258 e = entries;
259 if (n_entries == 1)
260 irqfd->irq_entry = *e;
261 else
262 irqfd->irq_entry.type = 0;
263
264 write_seqcount_end(&irqfd->irq_entry_sc);
265}
266
267#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
268void __attribute__((weak)) kvm_arch_irq_bypass_stop(
269 struct irq_bypass_consumer *cons)
270{
271}
272
273void __attribute__((weak)) kvm_arch_irq_bypass_start(
274 struct irq_bypass_consumer *cons)
275{
276}
277
278int __attribute__((weak)) kvm_arch_update_irqfd_routing(
279 struct kvm *kvm, unsigned int host_irq,
280 uint32_t guest_irq, bool set)
281{
282 return 0;
283}
284#endif
285
286static int
287kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
288{
289 struct kvm_kernel_irqfd *irqfd, *tmp;
290 struct fd f;
291 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
292 int ret;
293 __poll_t events;
294 int idx;
295
296 if (!kvm_arch_intc_initialized(kvm))
297 return -EAGAIN;
298
299 if (!kvm_arch_irqfd_allowed(kvm, args))
300 return -EINVAL;
301
302 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
303 if (!irqfd)
304 return -ENOMEM;
305
306 irqfd->kvm = kvm;
307 irqfd->gsi = args->gsi;
308 INIT_LIST_HEAD(&irqfd->list);
309 INIT_WORK(&irqfd->inject, irqfd_inject);
310 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
311 seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
312
313 f = fdget(args->fd);
314 if (!f.file) {
315 ret = -EBADF;
316 goto out;
317 }
318
319 eventfd = eventfd_ctx_fileget(f.file);
320 if (IS_ERR(eventfd)) {
321 ret = PTR_ERR(eventfd);
322 goto fail;
323 }
324
325 irqfd->eventfd = eventfd;
326
327 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
328 struct kvm_kernel_irqfd_resampler *resampler;
329
330 resamplefd = eventfd_ctx_fdget(args->resamplefd);
331 if (IS_ERR(resamplefd)) {
332 ret = PTR_ERR(resamplefd);
333 goto fail;
334 }
335
336 irqfd->resamplefd = resamplefd;
337 INIT_LIST_HEAD(&irqfd->resampler_link);
338
339 mutex_lock(&kvm->irqfds.resampler_lock);
340
341 list_for_each_entry(resampler,
342 &kvm->irqfds.resampler_list, link) {
343 if (resampler->notifier.gsi == irqfd->gsi) {
344 irqfd->resampler = resampler;
345 break;
346 }
347 }
348
349 if (!irqfd->resampler) {
350 resampler = kzalloc(sizeof(*resampler),
351 GFP_KERNEL_ACCOUNT);
352 if (!resampler) {
353 ret = -ENOMEM;
354 mutex_unlock(&kvm->irqfds.resampler_lock);
355 goto fail;
356 }
357
358 resampler->kvm = kvm;
359 INIT_LIST_HEAD(&resampler->list);
360 resampler->notifier.gsi = irqfd->gsi;
361 resampler->notifier.irq_acked = irqfd_resampler_ack;
362 INIT_LIST_HEAD(&resampler->link);
363
364 list_add(&resampler->link, &kvm->irqfds.resampler_list);
365 kvm_register_irq_ack_notifier(kvm,
366 &resampler->notifier);
367 irqfd->resampler = resampler;
368 }
369
370 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
371 synchronize_srcu(&kvm->irq_srcu);
372
373 mutex_unlock(&kvm->irqfds.resampler_lock);
374 }
375
376 /*
377 * Install our own custom wake-up handling so we are notified via
378 * a callback whenever someone signals the underlying eventfd
379 */
380 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
381 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
382
383 spin_lock_irq(&kvm->irqfds.lock);
384
385 ret = 0;
386 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
387 if (irqfd->eventfd != tmp->eventfd)
388 continue;
389 /* This fd is used for another irq already. */
390 ret = -EBUSY;
391 spin_unlock_irq(&kvm->irqfds.lock);
392 goto fail;
393 }
394
395 idx = srcu_read_lock(&kvm->irq_srcu);
396 irqfd_update(kvm, irqfd);
397
398 list_add_tail(&irqfd->list, &kvm->irqfds.items);
399
400 spin_unlock_irq(&kvm->irqfds.lock);
401
402 /*
403 * Check if there was an event already pending on the eventfd
404 * before we registered, and trigger it as if we didn't miss it.
405 */
406 events = vfs_poll(f.file, &irqfd->pt);
407
408 if (events & EPOLLIN)
409 schedule_work(&irqfd->inject);
410
411#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
412 if (kvm_arch_has_irq_bypass()) {
413 irqfd->consumer.token = (void *)irqfd->eventfd;
414 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
415 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
416 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
417 irqfd->consumer.start = kvm_arch_irq_bypass_start;
418 ret = irq_bypass_register_consumer(&irqfd->consumer);
419 if (ret)
420 pr_info("irq bypass consumer (token %p) registration fails: %d\n",
421 irqfd->consumer.token, ret);
422 }
423#endif
424
425 srcu_read_unlock(&kvm->irq_srcu, idx);
426
427 /*
428 * do not drop the file until the irqfd is fully initialized, otherwise
429 * we might race against the EPOLLHUP
430 */
431 fdput(f);
432 return 0;
433
434fail:
435 if (irqfd->resampler)
436 irqfd_resampler_shutdown(irqfd);
437
438 if (resamplefd && !IS_ERR(resamplefd))
439 eventfd_ctx_put(resamplefd);
440
441 if (eventfd && !IS_ERR(eventfd))
442 eventfd_ctx_put(eventfd);
443
444 fdput(f);
445
446out:
447 kfree(irqfd);
448 return ret;
449}
450
451bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
452{
453 struct kvm_irq_ack_notifier *kian;
454 int gsi, idx;
455
456 idx = srcu_read_lock(&kvm->irq_srcu);
457 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
458 if (gsi != -1)
459 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
460 link)
461 if (kian->gsi == gsi) {
462 srcu_read_unlock(&kvm->irq_srcu, idx);
463 return true;
464 }
465
466 srcu_read_unlock(&kvm->irq_srcu, idx);
467
468 return false;
469}
470EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
471
472void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
473{
474 struct kvm_irq_ack_notifier *kian;
475
476 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
477 link)
478 if (kian->gsi == gsi)
479 kian->irq_acked(kian);
480}
481
482void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
483{
484 int gsi, idx;
485
486 trace_kvm_ack_irq(irqchip, pin);
487
488 idx = srcu_read_lock(&kvm->irq_srcu);
489 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
490 if (gsi != -1)
491 kvm_notify_acked_gsi(kvm, gsi);
492 srcu_read_unlock(&kvm->irq_srcu, idx);
493}
494
495void kvm_register_irq_ack_notifier(struct kvm *kvm,
496 struct kvm_irq_ack_notifier *kian)
497{
498 mutex_lock(&kvm->irq_lock);
499 hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
500 mutex_unlock(&kvm->irq_lock);
501 kvm_arch_post_irq_ack_notifier_list_update(kvm);
502}
503
504void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
505 struct kvm_irq_ack_notifier *kian)
506{
507 mutex_lock(&kvm->irq_lock);
508 hlist_del_init_rcu(&kian->link);
509 mutex_unlock(&kvm->irq_lock);
510 synchronize_srcu(&kvm->irq_srcu);
511 kvm_arch_post_irq_ack_notifier_list_update(kvm);
512}
513#endif
514
515void
516kvm_eventfd_init(struct kvm *kvm)
517{
518#ifdef CONFIG_HAVE_KVM_IRQFD
519 spin_lock_init(&kvm->irqfds.lock);
520 INIT_LIST_HEAD(&kvm->irqfds.items);
521 INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
522 mutex_init(&kvm->irqfds.resampler_lock);
523#endif
524 INIT_LIST_HEAD(&kvm->ioeventfds);
525}
526
527#ifdef CONFIG_HAVE_KVM_IRQFD
528/*
529 * shutdown any irqfd's that match fd+gsi
530 */
531static int
532kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
533{
534 struct kvm_kernel_irqfd *irqfd, *tmp;
535 struct eventfd_ctx *eventfd;
536
537 eventfd = eventfd_ctx_fdget(args->fd);
538 if (IS_ERR(eventfd))
539 return PTR_ERR(eventfd);
540
541 spin_lock_irq(&kvm->irqfds.lock);
542
543 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
544 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
545 /*
546 * This clearing of irq_entry.type is needed for when
547 * another thread calls kvm_irq_routing_update before
548 * we flush workqueue below (we synchronize with
549 * kvm_irq_routing_update using irqfds.lock).
550 */
551 write_seqcount_begin(&irqfd->irq_entry_sc);
552 irqfd->irq_entry.type = 0;
553 write_seqcount_end(&irqfd->irq_entry_sc);
554 irqfd_deactivate(irqfd);
555 }
556 }
557
558 spin_unlock_irq(&kvm->irqfds.lock);
559 eventfd_ctx_put(eventfd);
560
561 /*
562 * Block until we know all outstanding shutdown jobs have completed
563 * so that we guarantee there will not be any more interrupts on this
564 * gsi once this deassign function returns.
565 */
566 flush_workqueue(irqfd_cleanup_wq);
567
568 return 0;
569}
570
571int
572kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
573{
574 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
575 return -EINVAL;
576
577 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
578 return kvm_irqfd_deassign(kvm, args);
579
580 return kvm_irqfd_assign(kvm, args);
581}
582
583/*
584 * This function is called as the kvm VM fd is being released. Shutdown all
585 * irqfds that still remain open
586 */
587void
588kvm_irqfd_release(struct kvm *kvm)
589{
590 struct kvm_kernel_irqfd *irqfd, *tmp;
591
592 spin_lock_irq(&kvm->irqfds.lock);
593
594 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
595 irqfd_deactivate(irqfd);
596
597 spin_unlock_irq(&kvm->irqfds.lock);
598
599 /*
600 * Block until we know all outstanding shutdown jobs have completed
601 * since we do not take a kvm* reference.
602 */
603 flush_workqueue(irqfd_cleanup_wq);
604
605}
606
607/*
608 * Take note of a change in irq routing.
609 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
610 */
611void kvm_irq_routing_update(struct kvm *kvm)
612{
613 struct kvm_kernel_irqfd *irqfd;
614
615 spin_lock_irq(&kvm->irqfds.lock);
616
617 list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
618 irqfd_update(kvm, irqfd);
619
620#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
621 if (irqfd->producer) {
622 int ret = kvm_arch_update_irqfd_routing(
623 irqfd->kvm, irqfd->producer->irq,
624 irqfd->gsi, 1);
625 WARN_ON(ret);
626 }
627#endif
628 }
629
630 spin_unlock_irq(&kvm->irqfds.lock);
631}
632
633/*
634 * create a host-wide workqueue for issuing deferred shutdown requests
635 * aggregated from all vm* instances. We need our own isolated
636 * queue to ease flushing work items when a VM exits.
637 */
638int kvm_irqfd_init(void)
639{
640 irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
641 if (!irqfd_cleanup_wq)
642 return -ENOMEM;
643
644 return 0;
645}
646
647void kvm_irqfd_exit(void)
648{
649 destroy_workqueue(irqfd_cleanup_wq);
650}
651#endif
652
653/*
654 * --------------------------------------------------------------------
655 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
656 *
657 * userspace can register a PIO/MMIO address with an eventfd for receiving
658 * notification when the memory has been touched.
659 * --------------------------------------------------------------------
660 */
661
662struct _ioeventfd {
663 struct list_head list;
664 u64 addr;
665 int length;
666 struct eventfd_ctx *eventfd;
667 u64 datamatch;
668 struct kvm_io_device dev;
669 u8 bus_idx;
670 bool wildcard;
671};
672
673static inline struct _ioeventfd *
674to_ioeventfd(struct kvm_io_device *dev)
675{
676 return container_of(dev, struct _ioeventfd, dev);
677}
678
679static void
680ioeventfd_release(struct _ioeventfd *p)
681{
682 eventfd_ctx_put(p->eventfd);
683 list_del(&p->list);
684 kfree(p);
685}
686
687static bool
688ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
689{
690 u64 _val;
691
692 if (addr != p->addr)
693 /* address must be precise for a hit */
694 return false;
695
696 if (!p->length)
697 /* length = 0 means only look at the address, so always a hit */
698 return true;
699
700 if (len != p->length)
701 /* address-range must be precise for a hit */
702 return false;
703
704 if (p->wildcard)
705 /* all else equal, wildcard is always a hit */
706 return true;
707
708 /* otherwise, we have to actually compare the data */
709
710 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
711
712 switch (len) {
713 case 1:
714 _val = *(u8 *)val;
715 break;
716 case 2:
717 _val = *(u16 *)val;
718 break;
719 case 4:
720 _val = *(u32 *)val;
721 break;
722 case 8:
723 _val = *(u64 *)val;
724 break;
725 default:
726 return false;
727 }
728
729 return _val == p->datamatch;
730}
731
732/* MMIO/PIO writes trigger an event if the addr/val match */
733static int
734ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
735 int len, const void *val)
736{
737 struct _ioeventfd *p = to_ioeventfd(this);
738
739 if (!ioeventfd_in_range(p, addr, len, val))
740 return -EOPNOTSUPP;
741
742 eventfd_signal(p->eventfd, 1);
743 return 0;
744}
745
746/*
747 * This function is called as KVM is completely shutting down. We do not
748 * need to worry about locking just nuke anything we have as quickly as possible
749 */
750static void
751ioeventfd_destructor(struct kvm_io_device *this)
752{
753 struct _ioeventfd *p = to_ioeventfd(this);
754
755 ioeventfd_release(p);
756}
757
758static const struct kvm_io_device_ops ioeventfd_ops = {
759 .write = ioeventfd_write,
760 .destructor = ioeventfd_destructor,
761};
762
763/* assumes kvm->slots_lock held */
764static bool
765ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
766{
767 struct _ioeventfd *_p;
768
769 list_for_each_entry(_p, &kvm->ioeventfds, list)
770 if (_p->bus_idx == p->bus_idx &&
771 _p->addr == p->addr &&
772 (!_p->length || !p->length ||
773 (_p->length == p->length &&
774 (_p->wildcard || p->wildcard ||
775 _p->datamatch == p->datamatch))))
776 return true;
777
778 return false;
779}
780
781static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
782{
783 if (flags & KVM_IOEVENTFD_FLAG_PIO)
784 return KVM_PIO_BUS;
785 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
786 return KVM_VIRTIO_CCW_NOTIFY_BUS;
787 return KVM_MMIO_BUS;
788}
789
790static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
791 enum kvm_bus bus_idx,
792 struct kvm_ioeventfd *args)
793{
794
795 struct eventfd_ctx *eventfd;
796 struct _ioeventfd *p;
797 int ret;
798
799 eventfd = eventfd_ctx_fdget(args->fd);
800 if (IS_ERR(eventfd))
801 return PTR_ERR(eventfd);
802
803 p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
804 if (!p) {
805 ret = -ENOMEM;
806 goto fail;
807 }
808
809 INIT_LIST_HEAD(&p->list);
810 p->addr = args->addr;
811 p->bus_idx = bus_idx;
812 p->length = args->len;
813 p->eventfd = eventfd;
814
815 /* The datamatch feature is optional, otherwise this is a wildcard */
816 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
817 p->datamatch = args->datamatch;
818 else
819 p->wildcard = true;
820
821 mutex_lock(&kvm->slots_lock);
822
823 /* Verify that there isn't a match already */
824 if (ioeventfd_check_collision(kvm, p)) {
825 ret = -EEXIST;
826 goto unlock_fail;
827 }
828
829 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
830
831 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
832 &p->dev);
833 if (ret < 0)
834 goto unlock_fail;
835
836 kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
837 list_add_tail(&p->list, &kvm->ioeventfds);
838
839 mutex_unlock(&kvm->slots_lock);
840
841 return 0;
842
843unlock_fail:
844 mutex_unlock(&kvm->slots_lock);
845
846fail:
847 kfree(p);
848 eventfd_ctx_put(eventfd);
849
850 return ret;
851}
852
853static int
854kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
855 struct kvm_ioeventfd *args)
856{
857 struct _ioeventfd *p, *tmp;
858 struct eventfd_ctx *eventfd;
859 struct kvm_io_bus *bus;
860 int ret = -ENOENT;
861 bool wildcard;
862
863 eventfd = eventfd_ctx_fdget(args->fd);
864 if (IS_ERR(eventfd))
865 return PTR_ERR(eventfd);
866
867 wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
868
869 mutex_lock(&kvm->slots_lock);
870
871 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
872
873 if (p->bus_idx != bus_idx ||
874 p->eventfd != eventfd ||
875 p->addr != args->addr ||
876 p->length != args->len ||
877 p->wildcard != wildcard)
878 continue;
879
880 if (!p->wildcard && p->datamatch != args->datamatch)
881 continue;
882
883 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
884 bus = kvm_get_bus(kvm, bus_idx);
885 if (bus)
886 bus->ioeventfd_count--;
887 ioeventfd_release(p);
888 ret = 0;
889 break;
890 }
891
892 mutex_unlock(&kvm->slots_lock);
893
894 eventfd_ctx_put(eventfd);
895
896 return ret;
897}
898
899static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
900{
901 enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
902 int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
903
904 if (!args->len && bus_idx == KVM_MMIO_BUS)
905 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
906
907 return ret;
908}
909
910static int
911kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
912{
913 enum kvm_bus bus_idx;
914 int ret;
915
916 bus_idx = ioeventfd_bus_from_flags(args->flags);
917 /* must be natural-word sized, or 0 to ignore length */
918 switch (args->len) {
919 case 0:
920 case 1:
921 case 2:
922 case 4:
923 case 8:
924 break;
925 default:
926 return -EINVAL;
927 }
928
929 /* check for range overflow */
930 if (args->addr + args->len < args->addr)
931 return -EINVAL;
932
933 /* check for extra flags that we don't understand */
934 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
935 return -EINVAL;
936
937 /* ioeventfd with no length can't be combined with DATAMATCH */
938 if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
939 return -EINVAL;
940
941 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
942 if (ret)
943 goto fail;
944
945 /* When length is ignored, MMIO is also put on a separate bus, for
946 * faster lookups.
947 */
948 if (!args->len && bus_idx == KVM_MMIO_BUS) {
949 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
950 if (ret < 0)
951 goto fast_fail;
952 }
953
954 return 0;
955
956fast_fail:
957 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
958fail:
959 return ret;
960}
961
962int
963kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
964{
965 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
966 return kvm_deassign_ioeventfd(kvm, args);
967
968 return kvm_assign_ioeventfd(kvm, args);
969}