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, irq: irqfd->gsi, level: 1,
50 line_status: false);
51 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irq: irqfd->gsi, level: 0,
52 line_status: false);
53 } else
54 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
55 irq: irqfd->gsi, level: 1, line_status: 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(ctx: irqfd->resamplefd, n: 1);
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 irq: resampler->notifier.gsi, level: 0, line_status: false);
85
86 idx = srcu_read_lock(ssp: &kvm->irq_srcu);
87 irqfd_resampler_notify(resampler);
88 srcu_read_unlock(ssp: &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(entry: &irqfd->resampler_link);
100 synchronize_srcu(ssp: &kvm->irq_srcu);
101
102 if (list_empty(head: &resampler->list)) {
103 list_del_rcu(entry: &resampler->link);
104 kvm_unregister_irq_ack_notifier(kvm, kian: &resampler->notifier);
105 /*
106 * synchronize_srcu(&kvm->irq_srcu) already called
107 * in kvm_unregister_irq_ack_notifier().
108 */
109 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
110 irq: resampler->notifier.gsi, level: 0, line_status: false);
111 kfree(objp: resampler);
112 }
113
114 mutex_unlock(lock: &kvm->irqfds.resampler_lock);
115}
116
117/*
118 * Race-free decouple logic (ordering is critical)
119 */
120static void
121irqfd_shutdown(struct work_struct *work)
122{
123 struct kvm_kernel_irqfd *irqfd =
124 container_of(work, struct kvm_kernel_irqfd, shutdown);
125 struct kvm *kvm = irqfd->kvm;
126 u64 cnt;
127
128 /* Make sure irqfd has been initialized in assign path. */
129 synchronize_srcu(ssp: &kvm->irq_srcu);
130
131 /*
132 * Synchronize with the wait-queue and unhook ourselves to prevent
133 * further events.
134 */
135 eventfd_ctx_remove_wait_queue(ctx: irqfd->eventfd, wait: &irqfd->wait, cnt: &cnt);
136
137 /*
138 * We know no new events will be scheduled at this point, so block
139 * until all previously outstanding events have completed
140 */
141 flush_work(work: &irqfd->inject);
142
143 if (irqfd->resampler) {
144 irqfd_resampler_shutdown(irqfd);
145 eventfd_ctx_put(ctx: irqfd->resamplefd);
146 }
147
148 /*
149 * It is now safe to release the object's resources
150 */
151#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
152 irq_bypass_unregister_consumer(&irqfd->consumer);
153#endif
154 eventfd_ctx_put(ctx: irqfd->eventfd);
155 kfree(objp: irqfd);
156}
157
158
159/* assumes kvm->irqfds.lock is held */
160static bool
161irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
162{
163 return list_empty(head: &irqfd->list) ? false : true;
164}
165
166/*
167 * Mark the irqfd as inactive and schedule it for removal
168 *
169 * assumes kvm->irqfds.lock is held
170 */
171static void
172irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
173{
174 BUG_ON(!irqfd_is_active(irqfd));
175
176 list_del_init(entry: &irqfd->list);
177
178 queue_work(wq: irqfd_cleanup_wq, work: &irqfd->shutdown);
179}
180
181int __attribute__((weak)) kvm_arch_set_irq_inatomic(
182 struct kvm_kernel_irq_routing_entry *irq,
183 struct kvm *kvm, int irq_source_id,
184 int level,
185 bool line_status)
186{
187 return -EWOULDBLOCK;
188}
189
190/*
191 * Called with wqh->lock held and interrupts disabled
192 */
193static int
194irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
195{
196 struct kvm_kernel_irqfd *irqfd =
197 container_of(wait, struct kvm_kernel_irqfd, wait);
198 __poll_t flags = key_to_poll(key);
199 struct kvm_kernel_irq_routing_entry irq;
200 struct kvm *kvm = irqfd->kvm;
201 unsigned seq;
202 int idx;
203 int ret = 0;
204
205 if (flags & EPOLLIN) {
206 u64 cnt;
207 eventfd_ctx_do_read(ctx: irqfd->eventfd, cnt: &cnt);
208
209 idx = srcu_read_lock(ssp: &kvm->irq_srcu);
210 do {
211 seq = read_seqcount_begin(&irqfd->irq_entry_sc);
212 irq = irqfd->irq_entry;
213 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
214 /* An event has been signaled, inject an interrupt */
215 if (kvm_arch_set_irq_inatomic(irq: &irq, kvm,
216 KVM_USERSPACE_IRQ_SOURCE_ID, level: 1,
217 line_status: false) == -EWOULDBLOCK)
218 schedule_work(work: &irqfd->inject);
219 srcu_read_unlock(ssp: &kvm->irq_srcu, idx);
220 ret = 1;
221 }
222
223 if (flags & EPOLLHUP) {
224 /* The eventfd is closing, detach from KVM */
225 unsigned long iflags;
226
227 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
228
229 /*
230 * We must check if someone deactivated the irqfd before
231 * we could acquire the irqfds.lock since the item is
232 * deactivated from the KVM side before it is unhooked from
233 * the wait-queue. If it is already deactivated, we can
234 * simply return knowing the other side will cleanup for us.
235 * We cannot race against the irqfd going away since the
236 * other side is required to acquire wqh->lock, which we hold
237 */
238 if (irqfd_is_active(irqfd))
239 irqfd_deactivate(irqfd);
240
241 spin_unlock_irqrestore(lock: &kvm->irqfds.lock, flags: iflags);
242 }
243
244 return ret;
245}
246
247static void
248irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
249 poll_table *pt)
250{
251 struct kvm_kernel_irqfd *irqfd =
252 container_of(pt, struct kvm_kernel_irqfd, pt);
253 add_wait_queue_priority(wq_head: wqh, wq_entry: &irqfd->wait);
254}
255
256/* Must be called under irqfds.lock */
257static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
258{
259 struct kvm_kernel_irq_routing_entry *e;
260 struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
261 int n_entries;
262
263 n_entries = kvm_irq_map_gsi(kvm, entries, gsi: irqfd->gsi);
264
265 write_seqcount_begin(&irqfd->irq_entry_sc);
266
267 e = entries;
268 if (n_entries == 1)
269 irqfd->irq_entry = *e;
270 else
271 irqfd->irq_entry.type = 0;
272
273 write_seqcount_end(&irqfd->irq_entry_sc);
274}
275
276#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
277void __attribute__((weak)) kvm_arch_irq_bypass_stop(
278 struct irq_bypass_consumer *cons)
279{
280}
281
282void __attribute__((weak)) kvm_arch_irq_bypass_start(
283 struct irq_bypass_consumer *cons)
284{
285}
286
287int __attribute__((weak)) kvm_arch_update_irqfd_routing(
288 struct kvm *kvm, unsigned int host_irq,
289 uint32_t guest_irq, bool set)
290{
291 return 0;
292}
293
294bool __attribute__((weak)) kvm_arch_irqfd_route_changed(
295 struct kvm_kernel_irq_routing_entry *old,
296 struct kvm_kernel_irq_routing_entry *new)
297{
298 return true;
299}
300#endif
301
302static int
303kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
304{
305 struct kvm_kernel_irqfd *irqfd, *tmp;
306 struct fd f;
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(size: 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(list: &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 f = fdget(fd: args->fd);
330 if (!f.file) {
331 ret = -EBADF;
332 goto out;
333 }
334
335 eventfd = eventfd_ctx_fileget(file: f.file);
336 if (IS_ERR(ptr: eventfd)) {
337 ret = PTR_ERR(ptr: eventfd);
338 goto fail;
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(fd: args->resamplefd);
347 if (IS_ERR(ptr: resamplefd)) {
348 ret = PTR_ERR(ptr: resamplefd);
349 goto fail;
350 }
351
352 irqfd->resamplefd = resamplefd;
353 INIT_LIST_HEAD(list: &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(size: sizeof(*resampler),
367 GFP_KERNEL_ACCOUNT);
368 if (!resampler) {
369 ret = -ENOMEM;
370 mutex_unlock(lock: &kvm->irqfds.resampler_lock);
371 goto fail;
372 }
373
374 resampler->kvm = kvm;
375 INIT_LIST_HEAD(list: &resampler->list);
376 resampler->notifier.gsi = irqfd->gsi;
377 resampler->notifier.irq_acked = irqfd_resampler_ack;
378 INIT_LIST_HEAD(list: &resampler->link);
379
380 list_add_rcu(new: &resampler->link, head: &kvm->irqfds.resampler_list);
381 kvm_register_irq_ack_notifier(kvm,
382 kian: &resampler->notifier);
383 irqfd->resampler = resampler;
384 }
385
386 list_add_rcu(new: &irqfd->resampler_link, head: &irqfd->resampler->list);
387 synchronize_srcu(ssp: &kvm->irq_srcu);
388
389 mutex_unlock(lock: &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(wq_entry: &irqfd->wait, func: irqfd_wakeup);
397 init_poll_funcptr(pt: &irqfd->pt, qproc: irqfd_ptable_queue_proc);
398
399 spin_lock_irq(lock: &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(lock: &kvm->irqfds.lock);
408 goto fail;
409 }
410
411 idx = srcu_read_lock(ssp: &kvm->irq_srcu);
412 irqfd_update(kvm, irqfd);
413
414 list_add_tail(new: &irqfd->list, head: &kvm->irqfds.items);
415
416 spin_unlock_irq(lock: &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(file: f.file, pt: &irqfd->pt);
423
424 if (events & EPOLLIN)
425 schedule_work(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(ssp: &kvm->irq_srcu, idx);
442
443 /*
444 * do not drop the file until the irqfd is fully initialized, otherwise
445 * we might race against the EPOLLHUP
446 */
447 fdput(fd: f);
448 return 0;
449
450fail:
451 if (irqfd->resampler)
452 irqfd_resampler_shutdown(irqfd);
453
454 if (resamplefd && !IS_ERR(ptr: resamplefd))
455 eventfd_ctx_put(ctx: resamplefd);
456
457 if (eventfd && !IS_ERR(ptr: eventfd))
458 eventfd_ctx_put(ctx: eventfd);
459
460 fdput(fd: f);
461
462out:
463 kfree(objp: irqfd);
464 return ret;
465}
466
467bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
468{
469 struct kvm_irq_ack_notifier *kian;
470 int gsi, idx;
471
472 idx = srcu_read_lock(ssp: &kvm->irq_srcu);
473 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
474 if (gsi != -1)
475 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
476 link, srcu_read_lock_held(&kvm->irq_srcu))
477 if (kian->gsi == gsi) {
478 srcu_read_unlock(ssp: &kvm->irq_srcu, idx);
479 return true;
480 }
481
482 srcu_read_unlock(ssp: &kvm->irq_srcu, idx);
483
484 return false;
485}
486EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
487
488void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
489{
490 struct kvm_irq_ack_notifier *kian;
491
492 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
493 link, srcu_read_lock_held(&kvm->irq_srcu))
494 if (kian->gsi == gsi)
495 kian->irq_acked(kian);
496}
497
498void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
499{
500 int gsi, idx;
501
502 trace_kvm_ack_irq(irqchip, pin);
503
504 idx = srcu_read_lock(ssp: &kvm->irq_srcu);
505 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
506 if (gsi != -1)
507 kvm_notify_acked_gsi(kvm, gsi);
508 srcu_read_unlock(ssp: &kvm->irq_srcu, idx);
509}
510
511void kvm_register_irq_ack_notifier(struct kvm *kvm,
512 struct kvm_irq_ack_notifier *kian)
513{
514 mutex_lock(&kvm->irq_lock);
515 hlist_add_head_rcu(n: &kian->link, h: &kvm->irq_ack_notifier_list);
516 mutex_unlock(lock: &kvm->irq_lock);
517 kvm_arch_post_irq_ack_notifier_list_update(kvm);
518}
519
520void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
521 struct kvm_irq_ack_notifier *kian)
522{
523 mutex_lock(&kvm->irq_lock);
524 hlist_del_init_rcu(n: &kian->link);
525 mutex_unlock(lock: &kvm->irq_lock);
526 synchronize_srcu(ssp: &kvm->irq_srcu);
527 kvm_arch_post_irq_ack_notifier_list_update(kvm);
528}
529#endif
530
531void
532kvm_eventfd_init(struct kvm *kvm)
533{
534#ifdef CONFIG_HAVE_KVM_IRQFD
535 spin_lock_init(&kvm->irqfds.lock);
536 INIT_LIST_HEAD(list: &kvm->irqfds.items);
537 INIT_LIST_HEAD(list: &kvm->irqfds.resampler_list);
538 mutex_init(&kvm->irqfds.resampler_lock);
539#endif
540 INIT_LIST_HEAD(list: &kvm->ioeventfds);
541}
542
543#ifdef CONFIG_HAVE_KVM_IRQFD
544/*
545 * shutdown any irqfd's that match fd+gsi
546 */
547static int
548kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
549{
550 struct kvm_kernel_irqfd *irqfd, *tmp;
551 struct eventfd_ctx *eventfd;
552
553 eventfd = eventfd_ctx_fdget(fd: args->fd);
554 if (IS_ERR(ptr: eventfd))
555 return PTR_ERR(ptr: eventfd);
556
557 spin_lock_irq(lock: &kvm->irqfds.lock);
558
559 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
560 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
561 /*
562 * This clearing of irq_entry.type is needed for when
563 * another thread calls kvm_irq_routing_update before
564 * we flush workqueue below (we synchronize with
565 * kvm_irq_routing_update using irqfds.lock).
566 */
567 write_seqcount_begin(&irqfd->irq_entry_sc);
568 irqfd->irq_entry.type = 0;
569 write_seqcount_end(&irqfd->irq_entry_sc);
570 irqfd_deactivate(irqfd);
571 }
572 }
573
574 spin_unlock_irq(lock: &kvm->irqfds.lock);
575 eventfd_ctx_put(ctx: eventfd);
576
577 /*
578 * Block until we know all outstanding shutdown jobs have completed
579 * so that we guarantee there will not be any more interrupts on this
580 * gsi once this deassign function returns.
581 */
582 flush_workqueue(irqfd_cleanup_wq);
583
584 return 0;
585}
586
587int
588kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
589{
590 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
591 return -EINVAL;
592
593 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
594 return kvm_irqfd_deassign(kvm, args);
595
596 return kvm_irqfd_assign(kvm, args);
597}
598
599/*
600 * This function is called as the kvm VM fd is being released. Shutdown all
601 * irqfds that still remain open
602 */
603void
604kvm_irqfd_release(struct kvm *kvm)
605{
606 struct kvm_kernel_irqfd *irqfd, *tmp;
607
608 spin_lock_irq(lock: &kvm->irqfds.lock);
609
610 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
611 irqfd_deactivate(irqfd);
612
613 spin_unlock_irq(lock: &kvm->irqfds.lock);
614
615 /*
616 * Block until we know all outstanding shutdown jobs have completed
617 * since we do not take a kvm* reference.
618 */
619 flush_workqueue(irqfd_cleanup_wq);
620
621}
622
623/*
624 * Take note of a change in irq routing.
625 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
626 */
627void kvm_irq_routing_update(struct kvm *kvm)
628{
629 struct kvm_kernel_irqfd *irqfd;
630
631 spin_lock_irq(lock: &kvm->irqfds.lock);
632
633 list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
634#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
635 /* Under irqfds.lock, so can read irq_entry safely */
636 struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry;
637#endif
638
639 irqfd_update(kvm, irqfd);
640
641#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
642 if (irqfd->producer &&
643 kvm_arch_irqfd_route_changed(old: &old, new: &irqfd->irq_entry)) {
644 int ret = kvm_arch_update_irqfd_routing(
645 kvm: irqfd->kvm, host_irq: irqfd->producer->irq,
646 guest_irq: irqfd->gsi, set: 1);
647 WARN_ON(ret);
648 }
649#endif
650 }
651
652 spin_unlock_irq(lock: &kvm->irqfds.lock);
653}
654
655bool kvm_notify_irqfd_resampler(struct kvm *kvm,
656 unsigned int irqchip,
657 unsigned int pin)
658{
659 struct kvm_kernel_irqfd_resampler *resampler;
660 int gsi, idx;
661
662 idx = srcu_read_lock(ssp: &kvm->irq_srcu);
663 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
664 if (gsi != -1) {
665 list_for_each_entry_srcu(resampler,
666 &kvm->irqfds.resampler_list, link,
667 srcu_read_lock_held(&kvm->irq_srcu)) {
668 if (resampler->notifier.gsi == gsi) {
669 irqfd_resampler_notify(resampler);
670 srcu_read_unlock(ssp: &kvm->irq_srcu, idx);
671 return true;
672 }
673 }
674 }
675 srcu_read_unlock(ssp: &kvm->irq_srcu, idx);
676
677 return false;
678}
679
680/*
681 * create a host-wide workqueue for issuing deferred shutdown requests
682 * aggregated from all vm* instances. We need our own isolated
683 * queue to ease flushing work items when a VM exits.
684 */
685int kvm_irqfd_init(void)
686{
687 irqfd_cleanup_wq = alloc_workqueue(fmt: "kvm-irqfd-cleanup", flags: 0, max_active: 0);
688 if (!irqfd_cleanup_wq)
689 return -ENOMEM;
690
691 return 0;
692}
693
694void kvm_irqfd_exit(void)
695{
696 destroy_workqueue(wq: irqfd_cleanup_wq);
697}
698#endif
699
700/*
701 * --------------------------------------------------------------------
702 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
703 *
704 * userspace can register a PIO/MMIO address with an eventfd for receiving
705 * notification when the memory has been touched.
706 * --------------------------------------------------------------------
707 */
708
709struct _ioeventfd {
710 struct list_head list;
711 u64 addr;
712 int length;
713 struct eventfd_ctx *eventfd;
714 u64 datamatch;
715 struct kvm_io_device dev;
716 u8 bus_idx;
717 bool wildcard;
718};
719
720static inline struct _ioeventfd *
721to_ioeventfd(struct kvm_io_device *dev)
722{
723 return container_of(dev, struct _ioeventfd, dev);
724}
725
726static void
727ioeventfd_release(struct _ioeventfd *p)
728{
729 eventfd_ctx_put(ctx: p->eventfd);
730 list_del(entry: &p->list);
731 kfree(objp: p);
732}
733
734static bool
735ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
736{
737 u64 _val;
738
739 if (addr != p->addr)
740 /* address must be precise for a hit */
741 return false;
742
743 if (!p->length)
744 /* length = 0 means only look at the address, so always a hit */
745 return true;
746
747 if (len != p->length)
748 /* address-range must be precise for a hit */
749 return false;
750
751 if (p->wildcard)
752 /* all else equal, wildcard is always a hit */
753 return true;
754
755 /* otherwise, we have to actually compare the data */
756
757 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
758
759 switch (len) {
760 case 1:
761 _val = *(u8 *)val;
762 break;
763 case 2:
764 _val = *(u16 *)val;
765 break;
766 case 4:
767 _val = *(u32 *)val;
768 break;
769 case 8:
770 _val = *(u64 *)val;
771 break;
772 default:
773 return false;
774 }
775
776 return _val == p->datamatch;
777}
778
779/* MMIO/PIO writes trigger an event if the addr/val match */
780static int
781ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
782 int len, const void *val)
783{
784 struct _ioeventfd *p = to_ioeventfd(dev: this);
785
786 if (!ioeventfd_in_range(p, addr, len, val))
787 return -EOPNOTSUPP;
788
789 eventfd_signal(ctx: p->eventfd, n: 1);
790 return 0;
791}
792
793/*
794 * This function is called as KVM is completely shutting down. We do not
795 * need to worry about locking just nuke anything we have as quickly as possible
796 */
797static void
798ioeventfd_destructor(struct kvm_io_device *this)
799{
800 struct _ioeventfd *p = to_ioeventfd(dev: this);
801
802 ioeventfd_release(p);
803}
804
805static const struct kvm_io_device_ops ioeventfd_ops = {
806 .write = ioeventfd_write,
807 .destructor = ioeventfd_destructor,
808};
809
810/* assumes kvm->slots_lock held */
811static bool
812ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
813{
814 struct _ioeventfd *_p;
815
816 list_for_each_entry(_p, &kvm->ioeventfds, list)
817 if (_p->bus_idx == p->bus_idx &&
818 _p->addr == p->addr &&
819 (!_p->length || !p->length ||
820 (_p->length == p->length &&
821 (_p->wildcard || p->wildcard ||
822 _p->datamatch == p->datamatch))))
823 return true;
824
825 return false;
826}
827
828static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
829{
830 if (flags & KVM_IOEVENTFD_FLAG_PIO)
831 return KVM_PIO_BUS;
832 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
833 return KVM_VIRTIO_CCW_NOTIFY_BUS;
834 return KVM_MMIO_BUS;
835}
836
837static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
838 enum kvm_bus bus_idx,
839 struct kvm_ioeventfd *args)
840{
841
842 struct eventfd_ctx *eventfd;
843 struct _ioeventfd *p;
844 int ret;
845
846 eventfd = eventfd_ctx_fdget(fd: args->fd);
847 if (IS_ERR(ptr: eventfd))
848 return PTR_ERR(ptr: eventfd);
849
850 p = kzalloc(size: sizeof(*p), GFP_KERNEL_ACCOUNT);
851 if (!p) {
852 ret = -ENOMEM;
853 goto fail;
854 }
855
856 INIT_LIST_HEAD(list: &p->list);
857 p->addr = args->addr;
858 p->bus_idx = bus_idx;
859 p->length = args->len;
860 p->eventfd = eventfd;
861
862 /* The datamatch feature is optional, otherwise this is a wildcard */
863 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
864 p->datamatch = args->datamatch;
865 else
866 p->wildcard = true;
867
868 mutex_lock(&kvm->slots_lock);
869
870 /* Verify that there isn't a match already */
871 if (ioeventfd_check_collision(kvm, p)) {
872 ret = -EEXIST;
873 goto unlock_fail;
874 }
875
876 kvm_iodevice_init(dev: &p->dev, ops: &ioeventfd_ops);
877
878 ret = kvm_io_bus_register_dev(kvm, bus_idx, addr: p->addr, len: p->length,
879 dev: &p->dev);
880 if (ret < 0)
881 goto unlock_fail;
882
883 kvm_get_bus(kvm, idx: bus_idx)->ioeventfd_count++;
884 list_add_tail(new: &p->list, head: &kvm->ioeventfds);
885
886 mutex_unlock(lock: &kvm->slots_lock);
887
888 return 0;
889
890unlock_fail:
891 mutex_unlock(lock: &kvm->slots_lock);
892 kfree(objp: p);
893
894fail:
895 eventfd_ctx_put(ctx: eventfd);
896
897 return ret;
898}
899
900static int
901kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
902 struct kvm_ioeventfd *args)
903{
904 struct _ioeventfd *p;
905 struct eventfd_ctx *eventfd;
906 struct kvm_io_bus *bus;
907 int ret = -ENOENT;
908 bool wildcard;
909
910 eventfd = eventfd_ctx_fdget(fd: args->fd);
911 if (IS_ERR(ptr: eventfd))
912 return PTR_ERR(ptr: eventfd);
913
914 wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
915
916 mutex_lock(&kvm->slots_lock);
917
918 list_for_each_entry(p, &kvm->ioeventfds, list) {
919 if (p->bus_idx != bus_idx ||
920 p->eventfd != eventfd ||
921 p->addr != args->addr ||
922 p->length != args->len ||
923 p->wildcard != wildcard)
924 continue;
925
926 if (!p->wildcard && p->datamatch != args->datamatch)
927 continue;
928
929 kvm_io_bus_unregister_dev(kvm, bus_idx, dev: &p->dev);
930 bus = kvm_get_bus(kvm, idx: bus_idx);
931 if (bus)
932 bus->ioeventfd_count--;
933 ret = 0;
934 break;
935 }
936
937 mutex_unlock(lock: &kvm->slots_lock);
938
939 eventfd_ctx_put(ctx: eventfd);
940
941 return ret;
942}
943
944static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
945{
946 enum kvm_bus bus_idx = ioeventfd_bus_from_flags(flags: args->flags);
947 int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
948
949 if (!args->len && bus_idx == KVM_MMIO_BUS)
950 kvm_deassign_ioeventfd_idx(kvm, bus_idx: KVM_FAST_MMIO_BUS, args);
951
952 return ret;
953}
954
955static int
956kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
957{
958 enum kvm_bus bus_idx;
959 int ret;
960
961 bus_idx = ioeventfd_bus_from_flags(flags: args->flags);
962 /* must be natural-word sized, or 0 to ignore length */
963 switch (args->len) {
964 case 0:
965 case 1:
966 case 2:
967 case 4:
968 case 8:
969 break;
970 default:
971 return -EINVAL;
972 }
973
974 /* check for range overflow */
975 if (args->addr + args->len < args->addr)
976 return -EINVAL;
977
978 /* check for extra flags that we don't understand */
979 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
980 return -EINVAL;
981
982 /* ioeventfd with no length can't be combined with DATAMATCH */
983 if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
984 return -EINVAL;
985
986 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
987 if (ret)
988 goto fail;
989
990 /* When length is ignored, MMIO is also put on a separate bus, for
991 * faster lookups.
992 */
993 if (!args->len && bus_idx == KVM_MMIO_BUS) {
994 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx: KVM_FAST_MMIO_BUS, args);
995 if (ret < 0)
996 goto fast_fail;
997 }
998
999 return 0;
1000
1001fast_fail:
1002 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
1003fail:
1004 return ret;
1005}
1006
1007int
1008kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
1009{
1010 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
1011 return kvm_deassign_ioeventfd(kvm, args);
1012
1013 return kvm_assign_ioeventfd(kvm, args);
1014}
1015

source code of linux/virt/kvm/eventfd.c