Loading...
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 initalized 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
195 if (flags & EPOLLIN) {
196 idx = srcu_read_lock(&kvm->irq_srcu);
197 do {
198 seq = read_seqcount_begin(&irqfd->irq_entry_sc);
199 irq = irqfd->irq_entry;
200 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
201 /* An event has been signaled, inject an interrupt */
202 if (kvm_arch_set_irq_inatomic(&irq, kvm,
203 KVM_USERSPACE_IRQ_SOURCE_ID, 1,
204 false) == -EWOULDBLOCK)
205 schedule_work(&irqfd->inject);
206 srcu_read_unlock(&kvm->irq_srcu, idx);
207 }
208
209 if (flags & EPOLLHUP) {
210 /* The eventfd is closing, detach from KVM */
211 unsigned long iflags;
212
213 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
214
215 /*
216 * We must check if someone deactivated the irqfd before
217 * we could acquire the irqfds.lock since the item is
218 * deactivated from the KVM side before it is unhooked from
219 * the wait-queue. If it is already deactivated, we can
220 * simply return knowing the other side will cleanup for us.
221 * We cannot race against the irqfd going away since the
222 * other side is required to acquire wqh->lock, which we hold
223 */
224 if (irqfd_is_active(irqfd))
225 irqfd_deactivate(irqfd);
226
227 spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
228 }
229
230 return 0;
231}
232
233static void
234irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
235 poll_table *pt)
236{
237 struct kvm_kernel_irqfd *irqfd =
238 container_of(pt, struct kvm_kernel_irqfd, pt);
239 add_wait_queue(wqh, &irqfd->wait);
240}
241
242/* Must be called under irqfds.lock */
243static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
244{
245 struct kvm_kernel_irq_routing_entry *e;
246 struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
247 int n_entries;
248
249 n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
250
251 write_seqcount_begin(&irqfd->irq_entry_sc);
252
253 e = entries;
254 if (n_entries == 1)
255 irqfd->irq_entry = *e;
256 else
257 irqfd->irq_entry.type = 0;
258
259 write_seqcount_end(&irqfd->irq_entry_sc);
260}
261
262#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
263void __attribute__((weak)) kvm_arch_irq_bypass_stop(
264 struct irq_bypass_consumer *cons)
265{
266}
267
268void __attribute__((weak)) kvm_arch_irq_bypass_start(
269 struct irq_bypass_consumer *cons)
270{
271}
272
273int __attribute__((weak)) kvm_arch_update_irqfd_routing(
274 struct kvm *kvm, unsigned int host_irq,
275 uint32_t guest_irq, bool set)
276{
277 return 0;
278}
279#endif
280
281static int
282kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
283{
284 struct kvm_kernel_irqfd *irqfd, *tmp;
285 struct fd f;
286 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
287 int ret;
288 __poll_t events;
289 int idx;
290
291 if (!kvm_arch_intc_initialized(kvm))
292 return -EAGAIN;
293
294 if (!kvm_arch_irqfd_allowed(kvm, args))
295 return -EINVAL;
296
297 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
298 if (!irqfd)
299 return -ENOMEM;
300
301 irqfd->kvm = kvm;
302 irqfd->gsi = args->gsi;
303 INIT_LIST_HEAD(&irqfd->list);
304 INIT_WORK(&irqfd->inject, irqfd_inject);
305 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
306 seqcount_init(&irqfd->irq_entry_sc);
307
308 f = fdget(args->fd);
309 if (!f.file) {
310 ret = -EBADF;
311 goto out;
312 }
313
314 eventfd = eventfd_ctx_fileget(f.file);
315 if (IS_ERR(eventfd)) {
316 ret = PTR_ERR(eventfd);
317 goto fail;
318 }
319
320 irqfd->eventfd = eventfd;
321
322 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
323 struct kvm_kernel_irqfd_resampler *resampler;
324
325 resamplefd = eventfd_ctx_fdget(args->resamplefd);
326 if (IS_ERR(resamplefd)) {
327 ret = PTR_ERR(resamplefd);
328 goto fail;
329 }
330
331 irqfd->resamplefd = resamplefd;
332 INIT_LIST_HEAD(&irqfd->resampler_link);
333
334 mutex_lock(&kvm->irqfds.resampler_lock);
335
336 list_for_each_entry(resampler,
337 &kvm->irqfds.resampler_list, link) {
338 if (resampler->notifier.gsi == irqfd->gsi) {
339 irqfd->resampler = resampler;
340 break;
341 }
342 }
343
344 if (!irqfd->resampler) {
345 resampler = kzalloc(sizeof(*resampler),
346 GFP_KERNEL_ACCOUNT);
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_srcu(&kvm->irq_srcu);
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 idx = srcu_read_lock(&kvm->irq_srcu);
391 irqfd_update(kvm, irqfd);
392
393 list_add_tail(&irqfd->list, &kvm->irqfds.items);
394
395 spin_unlock_irq(&kvm->irqfds.lock);
396
397 /*
398 * Check if there was an event already pending on the eventfd
399 * before we registered, and trigger it as if we didn't miss it.
400 */
401 events = vfs_poll(f.file, &irqfd->pt);
402
403 if (events & EPOLLIN)
404 schedule_work(&irqfd->inject);
405
406#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
407 if (kvm_arch_has_irq_bypass()) {
408 irqfd->consumer.token = (void *)irqfd->eventfd;
409 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
410 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
411 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
412 irqfd->consumer.start = kvm_arch_irq_bypass_start;
413 ret = irq_bypass_register_consumer(&irqfd->consumer);
414 if (ret)
415 pr_info("irq bypass consumer (token %p) registration fails: %d\n",
416 irqfd->consumer.token, ret);
417 }
418#endif
419
420 srcu_read_unlock(&kvm->irq_srcu, idx);
421
422 /*
423 * do not drop the file until the irqfd is fully initialized, otherwise
424 * we might race against the EPOLLHUP
425 */
426 fdput(f);
427 return 0;
428
429fail:
430 if (irqfd->resampler)
431 irqfd_resampler_shutdown(irqfd);
432
433 if (resamplefd && !IS_ERR(resamplefd))
434 eventfd_ctx_put(resamplefd);
435
436 if (eventfd && !IS_ERR(eventfd))
437 eventfd_ctx_put(eventfd);
438
439 fdput(f);
440
441out:
442 kfree(irqfd);
443 return ret;
444}
445
446bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
447{
448 struct kvm_irq_ack_notifier *kian;
449 int gsi, idx;
450
451 idx = srcu_read_lock(&kvm->irq_srcu);
452 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
453 if (gsi != -1)
454 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
455 link)
456 if (kian->gsi == gsi) {
457 srcu_read_unlock(&kvm->irq_srcu, idx);
458 return true;
459 }
460
461 srcu_read_unlock(&kvm->irq_srcu, idx);
462
463 return false;
464}
465EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
466
467void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
468{
469 struct kvm_irq_ack_notifier *kian;
470
471 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
472 link)
473 if (kian->gsi == gsi)
474 kian->irq_acked(kian);
475}
476
477void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
478{
479 int gsi, idx;
480
481 trace_kvm_ack_irq(irqchip, pin);
482
483 idx = srcu_read_lock(&kvm->irq_srcu);
484 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
485 if (gsi != -1)
486 kvm_notify_acked_gsi(kvm, gsi);
487 srcu_read_unlock(&kvm->irq_srcu, idx);
488}
489
490void kvm_register_irq_ack_notifier(struct kvm *kvm,
491 struct kvm_irq_ack_notifier *kian)
492{
493 mutex_lock(&kvm->irq_lock);
494 hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
495 mutex_unlock(&kvm->irq_lock);
496 kvm_arch_post_irq_ack_notifier_list_update(kvm);
497}
498
499void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
500 struct kvm_irq_ack_notifier *kian)
501{
502 mutex_lock(&kvm->irq_lock);
503 hlist_del_init_rcu(&kian->link);
504 mutex_unlock(&kvm->irq_lock);
505 synchronize_srcu(&kvm->irq_srcu);
506 kvm_arch_post_irq_ack_notifier_list_update(kvm);
507}
508#endif
509
510void
511kvm_eventfd_init(struct kvm *kvm)
512{
513#ifdef CONFIG_HAVE_KVM_IRQFD
514 spin_lock_init(&kvm->irqfds.lock);
515 INIT_LIST_HEAD(&kvm->irqfds.items);
516 INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
517 mutex_init(&kvm->irqfds.resampler_lock);
518#endif
519 INIT_LIST_HEAD(&kvm->ioeventfds);
520}
521
522#ifdef CONFIG_HAVE_KVM_IRQFD
523/*
524 * shutdown any irqfd's that match fd+gsi
525 */
526static int
527kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
528{
529 struct kvm_kernel_irqfd *irqfd, *tmp;
530 struct eventfd_ctx *eventfd;
531
532 eventfd = eventfd_ctx_fdget(args->fd);
533 if (IS_ERR(eventfd))
534 return PTR_ERR(eventfd);
535
536 spin_lock_irq(&kvm->irqfds.lock);
537
538 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
539 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
540 /*
541 * This clearing of irq_entry.type is needed for when
542 * another thread calls kvm_irq_routing_update before
543 * we flush workqueue below (we synchronize with
544 * kvm_irq_routing_update using irqfds.lock).
545 */
546 write_seqcount_begin(&irqfd->irq_entry_sc);
547 irqfd->irq_entry.type = 0;
548 write_seqcount_end(&irqfd->irq_entry_sc);
549 irqfd_deactivate(irqfd);
550 }
551 }
552
553 spin_unlock_irq(&kvm->irqfds.lock);
554 eventfd_ctx_put(eventfd);
555
556 /*
557 * Block until we know all outstanding shutdown jobs have completed
558 * so that we guarantee there will not be any more interrupts on this
559 * gsi once this deassign function returns.
560 */
561 flush_workqueue(irqfd_cleanup_wq);
562
563 return 0;
564}
565
566int
567kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
568{
569 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
570 return -EINVAL;
571
572 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
573 return kvm_irqfd_deassign(kvm, args);
574
575 return kvm_irqfd_assign(kvm, args);
576}
577
578/*
579 * This function is called as the kvm VM fd is being released. Shutdown all
580 * irqfds that still remain open
581 */
582void
583kvm_irqfd_release(struct kvm *kvm)
584{
585 struct kvm_kernel_irqfd *irqfd, *tmp;
586
587 spin_lock_irq(&kvm->irqfds.lock);
588
589 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
590 irqfd_deactivate(irqfd);
591
592 spin_unlock_irq(&kvm->irqfds.lock);
593
594 /*
595 * Block until we know all outstanding shutdown jobs have completed
596 * since we do not take a kvm* reference.
597 */
598 flush_workqueue(irqfd_cleanup_wq);
599
600}
601
602/*
603 * Take note of a change in irq routing.
604 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
605 */
606void kvm_irq_routing_update(struct kvm *kvm)
607{
608 struct kvm_kernel_irqfd *irqfd;
609
610 spin_lock_irq(&kvm->irqfds.lock);
611
612 list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
613 irqfd_update(kvm, irqfd);
614
615#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
616 if (irqfd->producer) {
617 int ret = kvm_arch_update_irqfd_routing(
618 irqfd->kvm, irqfd->producer->irq,
619 irqfd->gsi, 1);
620 WARN_ON(ret);
621 }
622#endif
623 }
624
625 spin_unlock_irq(&kvm->irqfds.lock);
626}
627
628/*
629 * create a host-wide workqueue for issuing deferred shutdown requests
630 * aggregated from all vm* instances. We need our own isolated
631 * queue to ease flushing work items when a VM exits.
632 */
633int kvm_irqfd_init(void)
634{
635 irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
636 if (!irqfd_cleanup_wq)
637 return -ENOMEM;
638
639 return 0;
640}
641
642void kvm_irqfd_exit(void)
643{
644 destroy_workqueue(irqfd_cleanup_wq);
645}
646#endif
647
648/*
649 * --------------------------------------------------------------------
650 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
651 *
652 * userspace can register a PIO/MMIO address with an eventfd for receiving
653 * notification when the memory has been touched.
654 * --------------------------------------------------------------------
655 */
656
657struct _ioeventfd {
658 struct list_head list;
659 u64 addr;
660 int length;
661 struct eventfd_ctx *eventfd;
662 u64 datamatch;
663 struct kvm_io_device dev;
664 u8 bus_idx;
665 bool wildcard;
666};
667
668static inline struct _ioeventfd *
669to_ioeventfd(struct kvm_io_device *dev)
670{
671 return container_of(dev, struct _ioeventfd, dev);
672}
673
674static void
675ioeventfd_release(struct _ioeventfd *p)
676{
677 eventfd_ctx_put(p->eventfd);
678 list_del(&p->list);
679 kfree(p);
680}
681
682static bool
683ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
684{
685 u64 _val;
686
687 if (addr != p->addr)
688 /* address must be precise for a hit */
689 return false;
690
691 if (!p->length)
692 /* length = 0 means only look at the address, so always a hit */
693 return true;
694
695 if (len != p->length)
696 /* address-range must be precise for a hit */
697 return false;
698
699 if (p->wildcard)
700 /* all else equal, wildcard is always a hit */
701 return true;
702
703 /* otherwise, we have to actually compare the data */
704
705 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
706
707 switch (len) {
708 case 1:
709 _val = *(u8 *)val;
710 break;
711 case 2:
712 _val = *(u16 *)val;
713 break;
714 case 4:
715 _val = *(u32 *)val;
716 break;
717 case 8:
718 _val = *(u64 *)val;
719 break;
720 default:
721 return false;
722 }
723
724 return _val == p->datamatch ? true : false;
725}
726
727/* MMIO/PIO writes trigger an event if the addr/val match */
728static int
729ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
730 int len, const void *val)
731{
732 struct _ioeventfd *p = to_ioeventfd(this);
733
734 if (!ioeventfd_in_range(p, addr, len, val))
735 return -EOPNOTSUPP;
736
737 eventfd_signal(p->eventfd, 1);
738 return 0;
739}
740
741/*
742 * This function is called as KVM is completely shutting down. We do not
743 * need to worry about locking just nuke anything we have as quickly as possible
744 */
745static void
746ioeventfd_destructor(struct kvm_io_device *this)
747{
748 struct _ioeventfd *p = to_ioeventfd(this);
749
750 ioeventfd_release(p);
751}
752
753static const struct kvm_io_device_ops ioeventfd_ops = {
754 .write = ioeventfd_write,
755 .destructor = ioeventfd_destructor,
756};
757
758/* assumes kvm->slots_lock held */
759static bool
760ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
761{
762 struct _ioeventfd *_p;
763
764 list_for_each_entry(_p, &kvm->ioeventfds, list)
765 if (_p->bus_idx == p->bus_idx &&
766 _p->addr == p->addr &&
767 (!_p->length || !p->length ||
768 (_p->length == p->length &&
769 (_p->wildcard || p->wildcard ||
770 _p->datamatch == p->datamatch))))
771 return true;
772
773 return false;
774}
775
776static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
777{
778 if (flags & KVM_IOEVENTFD_FLAG_PIO)
779 return KVM_PIO_BUS;
780 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
781 return KVM_VIRTIO_CCW_NOTIFY_BUS;
782 return KVM_MMIO_BUS;
783}
784
785static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
786 enum kvm_bus bus_idx,
787 struct kvm_ioeventfd *args)
788{
789
790 struct eventfd_ctx *eventfd;
791 struct _ioeventfd *p;
792 int ret;
793
794 eventfd = eventfd_ctx_fdget(args->fd);
795 if (IS_ERR(eventfd))
796 return PTR_ERR(eventfd);
797
798 p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
799 if (!p) {
800 ret = -ENOMEM;
801 goto fail;
802 }
803
804 INIT_LIST_HEAD(&p->list);
805 p->addr = args->addr;
806 p->bus_idx = bus_idx;
807 p->length = args->len;
808 p->eventfd = eventfd;
809
810 /* The datamatch feature is optional, otherwise this is a wildcard */
811 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
812 p->datamatch = args->datamatch;
813 else
814 p->wildcard = true;
815
816 mutex_lock(&kvm->slots_lock);
817
818 /* Verify that there isn't a match already */
819 if (ioeventfd_check_collision(kvm, p)) {
820 ret = -EEXIST;
821 goto unlock_fail;
822 }
823
824 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
825
826 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
827 &p->dev);
828 if (ret < 0)
829 goto unlock_fail;
830
831 kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
832 list_add_tail(&p->list, &kvm->ioeventfds);
833
834 mutex_unlock(&kvm->slots_lock);
835
836 return 0;
837
838unlock_fail:
839 mutex_unlock(&kvm->slots_lock);
840
841fail:
842 kfree(p);
843 eventfd_ctx_put(eventfd);
844
845 return ret;
846}
847
848static int
849kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
850 struct kvm_ioeventfd *args)
851{
852 struct _ioeventfd *p, *tmp;
853 struct eventfd_ctx *eventfd;
854 struct kvm_io_bus *bus;
855 int ret = -ENOENT;
856
857 eventfd = eventfd_ctx_fdget(args->fd);
858 if (IS_ERR(eventfd))
859 return PTR_ERR(eventfd);
860
861 mutex_lock(&kvm->slots_lock);
862
863 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
864 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
865
866 if (p->bus_idx != bus_idx ||
867 p->eventfd != eventfd ||
868 p->addr != args->addr ||
869 p->length != args->len ||
870 p->wildcard != wildcard)
871 continue;
872
873 if (!p->wildcard && p->datamatch != args->datamatch)
874 continue;
875
876 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
877 bus = kvm_get_bus(kvm, bus_idx);
878 if (bus)
879 bus->ioeventfd_count--;
880 ioeventfd_release(p);
881 ret = 0;
882 break;
883 }
884
885 mutex_unlock(&kvm->slots_lock);
886
887 eventfd_ctx_put(eventfd);
888
889 return ret;
890}
891
892static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
893{
894 enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
895 int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
896
897 if (!args->len && bus_idx == KVM_MMIO_BUS)
898 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
899
900 return ret;
901}
902
903static int
904kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
905{
906 enum kvm_bus bus_idx;
907 int ret;
908
909 bus_idx = ioeventfd_bus_from_flags(args->flags);
910 /* must be natural-word sized, or 0 to ignore length */
911 switch (args->len) {
912 case 0:
913 case 1:
914 case 2:
915 case 4:
916 case 8:
917 break;
918 default:
919 return -EINVAL;
920 }
921
922 /* check for range overflow */
923 if (args->addr + args->len < args->addr)
924 return -EINVAL;
925
926 /* check for extra flags that we don't understand */
927 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
928 return -EINVAL;
929
930 /* ioeventfd with no length can't be combined with DATAMATCH */
931 if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
932 return -EINVAL;
933
934 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
935 if (ret)
936 goto fail;
937
938 /* When length is ignored, MMIO is also put on a separate bus, for
939 * faster lookups.
940 */
941 if (!args->len && bus_idx == KVM_MMIO_BUS) {
942 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
943 if (ret < 0)
944 goto fast_fail;
945 }
946
947 return 0;
948
949fast_fail:
950 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
951fail:
952 return ret;
953}
954
955int
956kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
957{
958 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
959 return kvm_deassign_ioeventfd(kvm, args);
960
961 return kvm_assign_ioeventfd(kvm, args);
962}
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}