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