Merge v6.5-rc1 into drm-misc-fixes
[platform/kernel/linux-starfive.git] / virt / kvm / eventfd.c
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
33 static struct workqueue_struct *irqfd_cleanup_wq;
34
35 bool __attribute__((weak))
36 kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
37 {
38         return true;
39 }
40
41 static void
42 irqfd_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 static void irqfd_resampler_notify(struct kvm_kernel_irqfd_resampler *resampler)
59 {
60         struct kvm_kernel_irqfd *irqfd;
61
62         list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link,
63                                  srcu_read_lock_held(&resampler->kvm->irq_srcu))
64                 eventfd_signal(irqfd->resamplefd, 1);
65 }
66
67 /*
68  * Since resampler irqfds share an IRQ source ID, we de-assert once
69  * then notify all of the resampler irqfds using this GSI.  We can't
70  * do multiple de-asserts or we risk racing with incoming re-asserts.
71  */
72 static void
73 irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
74 {
75         struct kvm_kernel_irqfd_resampler *resampler;
76         struct kvm *kvm;
77         int idx;
78
79         resampler = container_of(kian,
80                         struct kvm_kernel_irqfd_resampler, notifier);
81         kvm = resampler->kvm;
82
83         kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
84                     resampler->notifier.gsi, 0, false);
85
86         idx = srcu_read_lock(&kvm->irq_srcu);
87         irqfd_resampler_notify(resampler);
88         srcu_read_unlock(&kvm->irq_srcu, idx);
89 }
90
91 static void
92 irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
93 {
94         struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
95         struct kvm *kvm = resampler->kvm;
96
97         mutex_lock(&kvm->irqfds.resampler_lock);
98
99         list_del_rcu(&irqfd->resampler_link);
100         synchronize_srcu(&kvm->irq_srcu);
101
102         if (list_empty(&resampler->list)) {
103                 list_del_rcu(&resampler->link);
104                 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
105                 /*
106                  * synchronize_srcu(&kvm->irq_srcu) already called
107                  * in kvm_unregister_irq_ack_notifier().
108                  */
109                 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
110                             resampler->notifier.gsi, 0, false);
111                 kfree(resampler);
112         }
113
114         mutex_unlock(&kvm->irqfds.resampler_lock);
115 }
116
117 /*
118  * Race-free decouple logic (ordering is critical)
119  */
120 static void
121 irqfd_shutdown(struct work_struct *work)
122 {
123         struct kvm_kernel_irqfd *irqfd =
124                 container_of(work, struct kvm_kernel_irqfd, shutdown);
125         struct kvm *kvm = irqfd->kvm;
126         u64 cnt;
127
128         /* Make sure irqfd has been initialized in assign path. */
129         synchronize_srcu(&kvm->irq_srcu);
130
131         /*
132          * Synchronize with the wait-queue and unhook ourselves to prevent
133          * further events.
134          */
135         eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
136
137         /*
138          * We know no new events will be scheduled at this point, so block
139          * until all previously outstanding events have completed
140          */
141         flush_work(&irqfd->inject);
142
143         if (irqfd->resampler) {
144                 irqfd_resampler_shutdown(irqfd);
145                 eventfd_ctx_put(irqfd->resamplefd);
146         }
147
148         /*
149          * It is now safe to release the object's resources
150          */
151 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
152         irq_bypass_unregister_consumer(&irqfd->consumer);
153 #endif
154         eventfd_ctx_put(irqfd->eventfd);
155         kfree(irqfd);
156 }
157
158
159 /* assumes kvm->irqfds.lock is held */
160 static bool
161 irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
162 {
163         return list_empty(&irqfd->list) ? false : true;
164 }
165
166 /*
167  * Mark the irqfd as inactive and schedule it for removal
168  *
169  * assumes kvm->irqfds.lock is held
170  */
171 static void
172 irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
173 {
174         BUG_ON(!irqfd_is_active(irqfd));
175
176         list_del_init(&irqfd->list);
177
178         queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
179 }
180
181 int __attribute__((weak)) kvm_arch_set_irq_inatomic(
182                                 struct kvm_kernel_irq_routing_entry *irq,
183                                 struct kvm *kvm, int irq_source_id,
184                                 int level,
185                                 bool line_status)
186 {
187         return -EWOULDBLOCK;
188 }
189
190 /*
191  * Called with wqh->lock held and interrupts disabled
192  */
193 static int
194 irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
195 {
196         struct kvm_kernel_irqfd *irqfd =
197                 container_of(wait, struct kvm_kernel_irqfd, wait);
198         __poll_t flags = key_to_poll(key);
199         struct kvm_kernel_irq_routing_entry irq;
200         struct kvm *kvm = irqfd->kvm;
201         unsigned seq;
202         int idx;
203         int ret = 0;
204
205         if (flags & EPOLLIN) {
206                 u64 cnt;
207                 eventfd_ctx_do_read(irqfd->eventfd, &cnt);
208
209                 idx = srcu_read_lock(&kvm->irq_srcu);
210                 do {
211                         seq = read_seqcount_begin(&irqfd->irq_entry_sc);
212                         irq = irqfd->irq_entry;
213                 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
214                 /* An event has been signaled, inject an interrupt */
215                 if (kvm_arch_set_irq_inatomic(&irq, kvm,
216                                               KVM_USERSPACE_IRQ_SOURCE_ID, 1,
217                                               false) == -EWOULDBLOCK)
218                         schedule_work(&irqfd->inject);
219                 srcu_read_unlock(&kvm->irq_srcu, idx);
220                 ret = 1;
221         }
222
223         if (flags & EPOLLHUP) {
224                 /* The eventfd is closing, detach from KVM */
225                 unsigned long iflags;
226
227                 spin_lock_irqsave(&kvm->irqfds.lock, iflags);
228
229                 /*
230                  * We must check if someone deactivated the irqfd before
231                  * we could acquire the irqfds.lock since the item is
232                  * deactivated from the KVM side before it is unhooked from
233                  * the wait-queue.  If it is already deactivated, we can
234                  * simply return knowing the other side will cleanup for us.
235                  * We cannot race against the irqfd going away since the
236                  * other side is required to acquire wqh->lock, which we hold
237                  */
238                 if (irqfd_is_active(irqfd))
239                         irqfd_deactivate(irqfd);
240
241                 spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
242         }
243
244         return ret;
245 }
246
247 static void
248 irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
249                         poll_table *pt)
250 {
251         struct kvm_kernel_irqfd *irqfd =
252                 container_of(pt, struct kvm_kernel_irqfd, pt);
253         add_wait_queue_priority(wqh, &irqfd->wait);
254 }
255
256 /* Must be called under irqfds.lock */
257 static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
258 {
259         struct kvm_kernel_irq_routing_entry *e;
260         struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
261         int n_entries;
262
263         n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
264
265         write_seqcount_begin(&irqfd->irq_entry_sc);
266
267         e = entries;
268         if (n_entries == 1)
269                 irqfd->irq_entry = *e;
270         else
271                 irqfd->irq_entry.type = 0;
272
273         write_seqcount_end(&irqfd->irq_entry_sc);
274 }
275
276 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
277 void __attribute__((weak)) kvm_arch_irq_bypass_stop(
278                                 struct irq_bypass_consumer *cons)
279 {
280 }
281
282 void __attribute__((weak)) kvm_arch_irq_bypass_start(
283                                 struct irq_bypass_consumer *cons)
284 {
285 }
286
287 int  __attribute__((weak)) kvm_arch_update_irqfd_routing(
288                                 struct kvm *kvm, unsigned int host_irq,
289                                 uint32_t guest_irq, bool set)
290 {
291         return 0;
292 }
293
294 bool __attribute__((weak)) kvm_arch_irqfd_route_changed(
295                                 struct kvm_kernel_irq_routing_entry *old,
296                                 struct kvm_kernel_irq_routing_entry *new)
297 {
298         return true;
299 }
300 #endif
301
302 static int
303 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
304 {
305         struct kvm_kernel_irqfd *irqfd, *tmp;
306         struct fd f;
307         struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
308         int ret;
309         __poll_t events;
310         int idx;
311
312         if (!kvm_arch_intc_initialized(kvm))
313                 return -EAGAIN;
314
315         if (!kvm_arch_irqfd_allowed(kvm, args))
316                 return -EINVAL;
317
318         irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
319         if (!irqfd)
320                 return -ENOMEM;
321
322         irqfd->kvm = kvm;
323         irqfd->gsi = args->gsi;
324         INIT_LIST_HEAD(&irqfd->list);
325         INIT_WORK(&irqfd->inject, irqfd_inject);
326         INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
327         seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
328
329         f = fdget(args->fd);
330         if (!f.file) {
331                 ret = -EBADF;
332                 goto out;
333         }
334
335         eventfd = eventfd_ctx_fileget(f.file);
336         if (IS_ERR(eventfd)) {
337                 ret = PTR_ERR(eventfd);
338                 goto fail;
339         }
340
341         irqfd->eventfd = eventfd;
342
343         if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
344                 struct kvm_kernel_irqfd_resampler *resampler;
345
346                 resamplefd = eventfd_ctx_fdget(args->resamplefd);
347                 if (IS_ERR(resamplefd)) {
348                         ret = PTR_ERR(resamplefd);
349                         goto fail;
350                 }
351
352                 irqfd->resamplefd = resamplefd;
353                 INIT_LIST_HEAD(&irqfd->resampler_link);
354
355                 mutex_lock(&kvm->irqfds.resampler_lock);
356
357                 list_for_each_entry(resampler,
358                                     &kvm->irqfds.resampler_list, link) {
359                         if (resampler->notifier.gsi == irqfd->gsi) {
360                                 irqfd->resampler = resampler;
361                                 break;
362                         }
363                 }
364
365                 if (!irqfd->resampler) {
366                         resampler = kzalloc(sizeof(*resampler),
367                                             GFP_KERNEL_ACCOUNT);
368                         if (!resampler) {
369                                 ret = -ENOMEM;
370                                 mutex_unlock(&kvm->irqfds.resampler_lock);
371                                 goto fail;
372                         }
373
374                         resampler->kvm = kvm;
375                         INIT_LIST_HEAD(&resampler->list);
376                         resampler->notifier.gsi = irqfd->gsi;
377                         resampler->notifier.irq_acked = irqfd_resampler_ack;
378                         INIT_LIST_HEAD(&resampler->link);
379
380                         list_add_rcu(&resampler->link, &kvm->irqfds.resampler_list);
381                         kvm_register_irq_ack_notifier(kvm,
382                                                       &resampler->notifier);
383                         irqfd->resampler = resampler;
384                 }
385
386                 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
387                 synchronize_srcu(&kvm->irq_srcu);
388
389                 mutex_unlock(&kvm->irqfds.resampler_lock);
390         }
391
392         /*
393          * Install our own custom wake-up handling so we are notified via
394          * a callback whenever someone signals the underlying eventfd
395          */
396         init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
397         init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
398
399         spin_lock_irq(&kvm->irqfds.lock);
400
401         ret = 0;
402         list_for_each_entry(tmp, &kvm->irqfds.items, list) {
403                 if (irqfd->eventfd != tmp->eventfd)
404                         continue;
405                 /* This fd is used for another irq already. */
406                 ret = -EBUSY;
407                 spin_unlock_irq(&kvm->irqfds.lock);
408                 goto fail;
409         }
410
411         idx = srcu_read_lock(&kvm->irq_srcu);
412         irqfd_update(kvm, irqfd);
413
414         list_add_tail(&irqfd->list, &kvm->irqfds.items);
415
416         spin_unlock_irq(&kvm->irqfds.lock);
417
418         /*
419          * Check if there was an event already pending on the eventfd
420          * before we registered, and trigger it as if we didn't miss it.
421          */
422         events = vfs_poll(f.file, &irqfd->pt);
423
424         if (events & EPOLLIN)
425                 schedule_work(&irqfd->inject);
426
427 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
428         if (kvm_arch_has_irq_bypass()) {
429                 irqfd->consumer.token = (void *)irqfd->eventfd;
430                 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
431                 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
432                 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
433                 irqfd->consumer.start = kvm_arch_irq_bypass_start;
434                 ret = irq_bypass_register_consumer(&irqfd->consumer);
435                 if (ret)
436                         pr_info("irq bypass consumer (token %p) registration fails: %d\n",
437                                 irqfd->consumer.token, ret);
438         }
439 #endif
440
441         srcu_read_unlock(&kvm->irq_srcu, idx);
442
443         /*
444          * do not drop the file until the irqfd is fully initialized, otherwise
445          * we might race against the EPOLLHUP
446          */
447         fdput(f);
448         return 0;
449
450 fail:
451         if (irqfd->resampler)
452                 irqfd_resampler_shutdown(irqfd);
453
454         if (resamplefd && !IS_ERR(resamplefd))
455                 eventfd_ctx_put(resamplefd);
456
457         if (eventfd && !IS_ERR(eventfd))
458                 eventfd_ctx_put(eventfd);
459
460         fdput(f);
461
462 out:
463         kfree(irqfd);
464         return ret;
465 }
466
467 bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
468 {
469         struct kvm_irq_ack_notifier *kian;
470         int gsi, idx;
471
472         idx = srcu_read_lock(&kvm->irq_srcu);
473         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
474         if (gsi != -1)
475                 hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
476                                           link, srcu_read_lock_held(&kvm->irq_srcu))
477                         if (kian->gsi == gsi) {
478                                 srcu_read_unlock(&kvm->irq_srcu, idx);
479                                 return true;
480                         }
481
482         srcu_read_unlock(&kvm->irq_srcu, idx);
483
484         return false;
485 }
486 EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
487
488 void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
489 {
490         struct kvm_irq_ack_notifier *kian;
491
492         hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
493                                   link, srcu_read_lock_held(&kvm->irq_srcu))
494                 if (kian->gsi == gsi)
495                         kian->irq_acked(kian);
496 }
497
498 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
499 {
500         int gsi, idx;
501
502         trace_kvm_ack_irq(irqchip, pin);
503
504         idx = srcu_read_lock(&kvm->irq_srcu);
505         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
506         if (gsi != -1)
507                 kvm_notify_acked_gsi(kvm, gsi);
508         srcu_read_unlock(&kvm->irq_srcu, idx);
509 }
510
511 void kvm_register_irq_ack_notifier(struct kvm *kvm,
512                                    struct kvm_irq_ack_notifier *kian)
513 {
514         mutex_lock(&kvm->irq_lock);
515         hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
516         mutex_unlock(&kvm->irq_lock);
517         kvm_arch_post_irq_ack_notifier_list_update(kvm);
518 }
519
520 void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
521                                     struct kvm_irq_ack_notifier *kian)
522 {
523         mutex_lock(&kvm->irq_lock);
524         hlist_del_init_rcu(&kian->link);
525         mutex_unlock(&kvm->irq_lock);
526         synchronize_srcu(&kvm->irq_srcu);
527         kvm_arch_post_irq_ack_notifier_list_update(kvm);
528 }
529 #endif
530
531 void
532 kvm_eventfd_init(struct kvm *kvm)
533 {
534 #ifdef CONFIG_HAVE_KVM_IRQFD
535         spin_lock_init(&kvm->irqfds.lock);
536         INIT_LIST_HEAD(&kvm->irqfds.items);
537         INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
538         mutex_init(&kvm->irqfds.resampler_lock);
539 #endif
540         INIT_LIST_HEAD(&kvm->ioeventfds);
541 }
542
543 #ifdef CONFIG_HAVE_KVM_IRQFD
544 /*
545  * shutdown any irqfd's that match fd+gsi
546  */
547 static int
548 kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
549 {
550         struct kvm_kernel_irqfd *irqfd, *tmp;
551         struct eventfd_ctx *eventfd;
552
553         eventfd = eventfd_ctx_fdget(args->fd);
554         if (IS_ERR(eventfd))
555                 return PTR_ERR(eventfd);
556
557         spin_lock_irq(&kvm->irqfds.lock);
558
559         list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
560                 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
561                         /*
562                          * This clearing of irq_entry.type is needed for when
563                          * another thread calls kvm_irq_routing_update before
564                          * we flush workqueue below (we synchronize with
565                          * kvm_irq_routing_update using irqfds.lock).
566                          */
567                         write_seqcount_begin(&irqfd->irq_entry_sc);
568                         irqfd->irq_entry.type = 0;
569                         write_seqcount_end(&irqfd->irq_entry_sc);
570                         irqfd_deactivate(irqfd);
571                 }
572         }
573
574         spin_unlock_irq(&kvm->irqfds.lock);
575         eventfd_ctx_put(eventfd);
576
577         /*
578          * Block until we know all outstanding shutdown jobs have completed
579          * so that we guarantee there will not be any more interrupts on this
580          * gsi once this deassign function returns.
581          */
582         flush_workqueue(irqfd_cleanup_wq);
583
584         return 0;
585 }
586
587 int
588 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
589 {
590         if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
591                 return -EINVAL;
592
593         if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
594                 return kvm_irqfd_deassign(kvm, args);
595
596         return kvm_irqfd_assign(kvm, args);
597 }
598
599 /*
600  * This function is called as the kvm VM fd is being released. Shutdown all
601  * irqfds that still remain open
602  */
603 void
604 kvm_irqfd_release(struct kvm *kvm)
605 {
606         struct kvm_kernel_irqfd *irqfd, *tmp;
607
608         spin_lock_irq(&kvm->irqfds.lock);
609
610         list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
611                 irqfd_deactivate(irqfd);
612
613         spin_unlock_irq(&kvm->irqfds.lock);
614
615         /*
616          * Block until we know all outstanding shutdown jobs have completed
617          * since we do not take a kvm* reference.
618          */
619         flush_workqueue(irqfd_cleanup_wq);
620
621 }
622
623 /*
624  * Take note of a change in irq routing.
625  * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
626  */
627 void kvm_irq_routing_update(struct kvm *kvm)
628 {
629         struct kvm_kernel_irqfd *irqfd;
630
631         spin_lock_irq(&kvm->irqfds.lock);
632
633         list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
634 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
635                 /* Under irqfds.lock, so can read irq_entry safely */
636                 struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry;
637 #endif
638
639                 irqfd_update(kvm, irqfd);
640
641 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
642                 if (irqfd->producer &&
643                     kvm_arch_irqfd_route_changed(&old, &irqfd->irq_entry)) {
644                         int ret = kvm_arch_update_irqfd_routing(
645                                         irqfd->kvm, irqfd->producer->irq,
646                                         irqfd->gsi, 1);
647                         WARN_ON(ret);
648                 }
649 #endif
650         }
651
652         spin_unlock_irq(&kvm->irqfds.lock);
653 }
654
655 bool kvm_notify_irqfd_resampler(struct kvm *kvm,
656                                 unsigned int irqchip,
657                                 unsigned int pin)
658 {
659         struct kvm_kernel_irqfd_resampler *resampler;
660         int gsi, idx;
661
662         idx = srcu_read_lock(&kvm->irq_srcu);
663         gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
664         if (gsi != -1) {
665                 list_for_each_entry_srcu(resampler,
666                                          &kvm->irqfds.resampler_list, link,
667                                          srcu_read_lock_held(&kvm->irq_srcu)) {
668                         if (resampler->notifier.gsi == gsi) {
669                                 irqfd_resampler_notify(resampler);
670                                 srcu_read_unlock(&kvm->irq_srcu, idx);
671                                 return true;
672                         }
673                 }
674         }
675         srcu_read_unlock(&kvm->irq_srcu, idx);
676
677         return false;
678 }
679
680 /*
681  * create a host-wide workqueue for issuing deferred shutdown requests
682  * aggregated from all vm* instances. We need our own isolated
683  * queue to ease flushing work items when a VM exits.
684  */
685 int kvm_irqfd_init(void)
686 {
687         irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
688         if (!irqfd_cleanup_wq)
689                 return -ENOMEM;
690
691         return 0;
692 }
693
694 void kvm_irqfd_exit(void)
695 {
696         destroy_workqueue(irqfd_cleanup_wq);
697 }
698 #endif
699
700 /*
701  * --------------------------------------------------------------------
702  * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
703  *
704  * userspace can register a PIO/MMIO address with an eventfd for receiving
705  * notification when the memory has been touched.
706  * --------------------------------------------------------------------
707  */
708
709 struct _ioeventfd {
710         struct list_head     list;
711         u64                  addr;
712         int                  length;
713         struct eventfd_ctx  *eventfd;
714         u64                  datamatch;
715         struct kvm_io_device dev;
716         u8                   bus_idx;
717         bool                 wildcard;
718 };
719
720 static inline struct _ioeventfd *
721 to_ioeventfd(struct kvm_io_device *dev)
722 {
723         return container_of(dev, struct _ioeventfd, dev);
724 }
725
726 static void
727 ioeventfd_release(struct _ioeventfd *p)
728 {
729         eventfd_ctx_put(p->eventfd);
730         list_del(&p->list);
731         kfree(p);
732 }
733
734 static bool
735 ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
736 {
737         u64 _val;
738
739         if (addr != p->addr)
740                 /* address must be precise for a hit */
741                 return false;
742
743         if (!p->length)
744                 /* length = 0 means only look at the address, so always a hit */
745                 return true;
746
747         if (len != p->length)
748                 /* address-range must be precise for a hit */
749                 return false;
750
751         if (p->wildcard)
752                 /* all else equal, wildcard is always a hit */
753                 return true;
754
755         /* otherwise, we have to actually compare the data */
756
757         BUG_ON(!IS_ALIGNED((unsigned long)val, len));
758
759         switch (len) {
760         case 1:
761                 _val = *(u8 *)val;
762                 break;
763         case 2:
764                 _val = *(u16 *)val;
765                 break;
766         case 4:
767                 _val = *(u32 *)val;
768                 break;
769         case 8:
770                 _val = *(u64 *)val;
771                 break;
772         default:
773                 return false;
774         }
775
776         return _val == p->datamatch;
777 }
778
779 /* MMIO/PIO writes trigger an event if the addr/val match */
780 static int
781 ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
782                 int len, const void *val)
783 {
784         struct _ioeventfd *p = to_ioeventfd(this);
785
786         if (!ioeventfd_in_range(p, addr, len, val))
787                 return -EOPNOTSUPP;
788
789         eventfd_signal(p->eventfd, 1);
790         return 0;
791 }
792
793 /*
794  * This function is called as KVM is completely shutting down.  We do not
795  * need to worry about locking just nuke anything we have as quickly as possible
796  */
797 static void
798 ioeventfd_destructor(struct kvm_io_device *this)
799 {
800         struct _ioeventfd *p = to_ioeventfd(this);
801
802         ioeventfd_release(p);
803 }
804
805 static const struct kvm_io_device_ops ioeventfd_ops = {
806         .write      = ioeventfd_write,
807         .destructor = ioeventfd_destructor,
808 };
809
810 /* assumes kvm->slots_lock held */
811 static bool
812 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
813 {
814         struct _ioeventfd *_p;
815
816         list_for_each_entry(_p, &kvm->ioeventfds, list)
817                 if (_p->bus_idx == p->bus_idx &&
818                     _p->addr == p->addr &&
819                     (!_p->length || !p->length ||
820                      (_p->length == p->length &&
821                       (_p->wildcard || p->wildcard ||
822                        _p->datamatch == p->datamatch))))
823                         return true;
824
825         return false;
826 }
827
828 static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
829 {
830         if (flags & KVM_IOEVENTFD_FLAG_PIO)
831                 return KVM_PIO_BUS;
832         if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
833                 return KVM_VIRTIO_CCW_NOTIFY_BUS;
834         return KVM_MMIO_BUS;
835 }
836
837 static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
838                                 enum kvm_bus bus_idx,
839                                 struct kvm_ioeventfd *args)
840 {
841
842         struct eventfd_ctx *eventfd;
843         struct _ioeventfd *p;
844         int ret;
845
846         eventfd = eventfd_ctx_fdget(args->fd);
847         if (IS_ERR(eventfd))
848                 return PTR_ERR(eventfd);
849
850         p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
851         if (!p) {
852                 ret = -ENOMEM;
853                 goto fail;
854         }
855
856         INIT_LIST_HEAD(&p->list);
857         p->addr    = args->addr;
858         p->bus_idx = bus_idx;
859         p->length  = args->len;
860         p->eventfd = eventfd;
861
862         /* The datamatch feature is optional, otherwise this is a wildcard */
863         if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
864                 p->datamatch = args->datamatch;
865         else
866                 p->wildcard = true;
867
868         mutex_lock(&kvm->slots_lock);
869
870         /* Verify that there isn't a match already */
871         if (ioeventfd_check_collision(kvm, p)) {
872                 ret = -EEXIST;
873                 goto unlock_fail;
874         }
875
876         kvm_iodevice_init(&p->dev, &ioeventfd_ops);
877
878         ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
879                                       &p->dev);
880         if (ret < 0)
881                 goto unlock_fail;
882
883         kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
884         list_add_tail(&p->list, &kvm->ioeventfds);
885
886         mutex_unlock(&kvm->slots_lock);
887
888         return 0;
889
890 unlock_fail:
891         mutex_unlock(&kvm->slots_lock);
892         kfree(p);
893
894 fail:
895         eventfd_ctx_put(eventfd);
896
897         return ret;
898 }
899
900 static int
901 kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
902                            struct kvm_ioeventfd *args)
903 {
904         struct _ioeventfd        *p;
905         struct eventfd_ctx       *eventfd;
906         struct kvm_io_bus        *bus;
907         int                       ret = -ENOENT;
908         bool                      wildcard;
909
910         eventfd = eventfd_ctx_fdget(args->fd);
911         if (IS_ERR(eventfd))
912                 return PTR_ERR(eventfd);
913
914         wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
915
916         mutex_lock(&kvm->slots_lock);
917
918         list_for_each_entry(p, &kvm->ioeventfds, list) {
919                 if (p->bus_idx != bus_idx ||
920                     p->eventfd != eventfd  ||
921                     p->addr != args->addr  ||
922                     p->length != args->len ||
923                     p->wildcard != wildcard)
924                         continue;
925
926                 if (!p->wildcard && p->datamatch != args->datamatch)
927                         continue;
928
929                 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
930                 bus = kvm_get_bus(kvm, bus_idx);
931                 if (bus)
932                         bus->ioeventfd_count--;
933                 ret = 0;
934                 break;
935         }
936
937         mutex_unlock(&kvm->slots_lock);
938
939         eventfd_ctx_put(eventfd);
940
941         return ret;
942 }
943
944 static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
945 {
946         enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
947         int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
948
949         if (!args->len && bus_idx == KVM_MMIO_BUS)
950                 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
951
952         return ret;
953 }
954
955 static int
956 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
957 {
958         enum kvm_bus              bus_idx;
959         int ret;
960
961         bus_idx = ioeventfd_bus_from_flags(args->flags);
962         /* must be natural-word sized, or 0 to ignore length */
963         switch (args->len) {
964         case 0:
965         case 1:
966         case 2:
967         case 4:
968         case 8:
969                 break;
970         default:
971                 return -EINVAL;
972         }
973
974         /* check for range overflow */
975         if (args->addr + args->len < args->addr)
976                 return -EINVAL;
977
978         /* check for extra flags that we don't understand */
979         if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
980                 return -EINVAL;
981
982         /* ioeventfd with no length can't be combined with DATAMATCH */
983         if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
984                 return -EINVAL;
985
986         ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
987         if (ret)
988                 goto fail;
989
990         /* When length is ignored, MMIO is also put on a separate bus, for
991          * faster lookups.
992          */
993         if (!args->len && bus_idx == KVM_MMIO_BUS) {
994                 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
995                 if (ret < 0)
996                         goto fast_fail;
997         }
998
999         return 0;
1000
1001 fast_fail:
1002         kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
1003 fail:
1004         return ret;
1005 }
1006
1007 int
1008 kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
1009 {
1010         if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
1011                 return kvm_deassign_ioeventfd(kvm, args);
1012
1013         return kvm_assign_ioeventfd(kvm, args);
1014 }