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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_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// 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}