blob: 66cf65b510b11c1c245db3b6a435e040ac3606fc [file] [log] [blame]
Gregory Haskins721eecb2009-05-20 10:30:49 -04001/*
2 * kvm eventfd support - use eventfd objects to signal various KVM events
3 *
4 * Copyright 2009 Novell. All Rights Reserved.
Avi Kivity221d0592010-05-23 18:37:00 +03005 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
Gregory Haskins721eecb2009-05-20 10:30:49 -04006 *
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>
Gregory Haskinsd34e6b12009-07-07 17:08:49 -040025#include <linux/kvm.h>
Gregory Haskins721eecb2009-05-20 10:30:49 -040026#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>
Gregory Haskinsd34e6b12009-07-07 17:08:49 -040033#include <linux/kernel.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090034#include <linux/slab.h>
Gregory Haskinsd34e6b12009-07-07 17:08:49 -040035
36#include "iodev.h"
Gregory Haskins721eecb2009-05-20 10:30:49 -040037
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 struct kvm *kvm;
48 struct eventfd_ctx *eventfd;
49 int gsi;
50 struct list_head list;
51 poll_table pt;
Gregory Haskins721eecb2009-05-20 10:30:49 -040052 wait_queue_t wait;
53 struct work_struct inject;
54 struct work_struct shutdown;
55};
56
57static struct workqueue_struct *irqfd_cleanup_wq;
58
59static void
60irqfd_inject(struct work_struct *work)
61{
62 struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
63 struct kvm *kvm = irqfd->kvm;
64
Gregory Haskins721eecb2009-05-20 10:30:49 -040065 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
66 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
Gregory Haskins721eecb2009-05-20 10:30:49 -040067}
68
69/*
70 * Race-free decouple logic (ordering is critical)
71 */
72static void
73irqfd_shutdown(struct work_struct *work)
74{
75 struct _irqfd *irqfd = container_of(work, struct _irqfd, shutdown);
Michael S. Tsirkinb6a114d2010-01-13 19:12:30 +020076 u64 cnt;
Gregory Haskins721eecb2009-05-20 10:30:49 -040077
78 /*
79 * Synchronize with the wait-queue and unhook ourselves to prevent
80 * further events.
81 */
Michael S. Tsirkinb6a114d2010-01-13 19:12:30 +020082 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
Gregory Haskins721eecb2009-05-20 10:30:49 -040083
84 /*
85 * We know no new events will be scheduled at this point, so block
86 * until all previously outstanding events have completed
87 */
88 flush_work(&irqfd->inject);
89
90 /*
91 * It is now safe to release the object's resources
92 */
93 eventfd_ctx_put(irqfd->eventfd);
94 kfree(irqfd);
95}
96
97
98/* assumes kvm->irqfds.lock is held */
99static bool
100irqfd_is_active(struct _irqfd *irqfd)
101{
102 return list_empty(&irqfd->list) ? false : true;
103}
104
105/*
106 * Mark the irqfd as inactive and schedule it for removal
107 *
108 * assumes kvm->irqfds.lock is held
109 */
110static void
111irqfd_deactivate(struct _irqfd *irqfd)
112{
113 BUG_ON(!irqfd_is_active(irqfd));
114
115 list_del_init(&irqfd->list);
116
117 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
118}
119
120/*
121 * Called with wqh->lock held and interrupts disabled
122 */
123static int
124irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
125{
126 struct _irqfd *irqfd = container_of(wait, struct _irqfd, wait);
127 unsigned long flags = (unsigned long)key;
128
129 if (flags & POLLIN)
130 /* An event has been signaled, inject an interrupt */
131 schedule_work(&irqfd->inject);
132
133 if (flags & POLLHUP) {
134 /* The eventfd is closing, detach from KVM */
135 struct kvm *kvm = irqfd->kvm;
136 unsigned long flags;
137
138 spin_lock_irqsave(&kvm->irqfds.lock, flags);
139
140 /*
141 * We must check if someone deactivated the irqfd before
142 * we could acquire the irqfds.lock since the item is
143 * deactivated from the KVM side before it is unhooked from
144 * the wait-queue. If it is already deactivated, we can
145 * simply return knowing the other side will cleanup for us.
146 * We cannot race against the irqfd going away since the
147 * other side is required to acquire wqh->lock, which we hold
148 */
149 if (irqfd_is_active(irqfd))
150 irqfd_deactivate(irqfd);
151
152 spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
153 }
154
155 return 0;
156}
157
158static void
159irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
160 poll_table *pt)
161{
162 struct _irqfd *irqfd = container_of(pt, struct _irqfd, pt);
Gregory Haskins721eecb2009-05-20 10:30:49 -0400163 add_wait_queue(wqh, &irqfd->wait);
164}
165
166static int
167kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
168{
Michael S. Tsirkinf1d1c302010-01-13 18:58:09 +0200169 struct _irqfd *irqfd, *tmp;
Gregory Haskins721eecb2009-05-20 10:30:49 -0400170 struct file *file = NULL;
171 struct eventfd_ctx *eventfd = NULL;
172 int ret;
173 unsigned int events;
174
175 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
176 if (!irqfd)
177 return -ENOMEM;
178
179 irqfd->kvm = kvm;
180 irqfd->gsi = gsi;
181 INIT_LIST_HEAD(&irqfd->list);
182 INIT_WORK(&irqfd->inject, irqfd_inject);
183 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
184
185 file = eventfd_fget(fd);
186 if (IS_ERR(file)) {
187 ret = PTR_ERR(file);
188 goto fail;
189 }
190
191 eventfd = eventfd_ctx_fileget(file);
192 if (IS_ERR(eventfd)) {
193 ret = PTR_ERR(eventfd);
194 goto fail;
195 }
196
197 irqfd->eventfd = eventfd;
198
199 /*
200 * Install our own custom wake-up handling so we are notified via
201 * a callback whenever someone signals the underlying eventfd
202 */
203 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
204 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
205
Michael S. Tsirkinf1d1c302010-01-13 18:58:09 +0200206 spin_lock_irq(&kvm->irqfds.lock);
207
208 ret = 0;
209 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
210 if (irqfd->eventfd != tmp->eventfd)
211 continue;
212 /* This fd is used for another irq already. */
213 ret = -EBUSY;
214 spin_unlock_irq(&kvm->irqfds.lock);
215 goto fail;
216 }
217
Gregory Haskins721eecb2009-05-20 10:30:49 -0400218 events = file->f_op->poll(file, &irqfd->pt);
219
Gregory Haskins721eecb2009-05-20 10:30:49 -0400220 list_add_tail(&irqfd->list, &kvm->irqfds.items);
221 spin_unlock_irq(&kvm->irqfds.lock);
222
223 /*
224 * Check if there was an event already pending on the eventfd
225 * before we registered, and trigger it as if we didn't miss it.
226 */
227 if (events & POLLIN)
228 schedule_work(&irqfd->inject);
229
230 /*
231 * do not drop the file until the irqfd is fully initialized, otherwise
232 * we might race against the POLLHUP
233 */
234 fput(file);
235
236 return 0;
237
238fail:
239 if (eventfd && !IS_ERR(eventfd))
240 eventfd_ctx_put(eventfd);
241
Julia Lawall62230112009-07-28 17:53:24 +0200242 if (!IS_ERR(file))
Gregory Haskins721eecb2009-05-20 10:30:49 -0400243 fput(file);
244
245 kfree(irqfd);
246 return ret;
247}
248
249void
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400250kvm_eventfd_init(struct kvm *kvm)
Gregory Haskins721eecb2009-05-20 10:30:49 -0400251{
252 spin_lock_init(&kvm->irqfds.lock);
253 INIT_LIST_HEAD(&kvm->irqfds.items);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400254 INIT_LIST_HEAD(&kvm->ioeventfds);
Gregory Haskins721eecb2009-05-20 10:30:49 -0400255}
256
257/*
258 * shutdown any irqfd's that match fd+gsi
259 */
260static int
261kvm_irqfd_deassign(struct kvm *kvm, int fd, int gsi)
262{
263 struct _irqfd *irqfd, *tmp;
264 struct eventfd_ctx *eventfd;
265
266 eventfd = eventfd_ctx_fdget(fd);
267 if (IS_ERR(eventfd))
268 return PTR_ERR(eventfd);
269
270 spin_lock_irq(&kvm->irqfds.lock);
271
272 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
273 if (irqfd->eventfd == eventfd && irqfd->gsi == gsi)
274 irqfd_deactivate(irqfd);
275 }
276
277 spin_unlock_irq(&kvm->irqfds.lock);
278 eventfd_ctx_put(eventfd);
279
280 /*
281 * Block until we know all outstanding shutdown jobs have completed
282 * so that we guarantee there will not be any more interrupts on this
283 * gsi once this deassign function returns.
284 */
285 flush_workqueue(irqfd_cleanup_wq);
286
287 return 0;
288}
289
290int
291kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags)
292{
293 if (flags & KVM_IRQFD_FLAG_DEASSIGN)
294 return kvm_irqfd_deassign(kvm, fd, gsi);
295
296 return kvm_irqfd_assign(kvm, fd, gsi);
297}
298
299/*
300 * This function is called as the kvm VM fd is being released. Shutdown all
301 * irqfds that still remain open
302 */
303void
304kvm_irqfd_release(struct kvm *kvm)
305{
306 struct _irqfd *irqfd, *tmp;
307
308 spin_lock_irq(&kvm->irqfds.lock);
309
310 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
311 irqfd_deactivate(irqfd);
312
313 spin_unlock_irq(&kvm->irqfds.lock);
314
315 /*
316 * Block until we know all outstanding shutdown jobs have completed
317 * since we do not take a kvm* reference.
318 */
319 flush_workqueue(irqfd_cleanup_wq);
320
321}
322
323/*
324 * create a host-wide workqueue for issuing deferred shutdown requests
325 * aggregated from all vm* instances. We need our own isolated single-thread
326 * queue to prevent deadlock against flushing the normal work-queue.
327 */
328static int __init irqfd_module_init(void)
329{
330 irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
331 if (!irqfd_cleanup_wq)
332 return -ENOMEM;
333
334 return 0;
335}
336
337static void __exit irqfd_module_exit(void)
338{
339 destroy_workqueue(irqfd_cleanup_wq);
340}
341
342module_init(irqfd_module_init);
343module_exit(irqfd_module_exit);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400344
345/*
346 * --------------------------------------------------------------------
347 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
348 *
349 * userspace can register a PIO/MMIO address with an eventfd for receiving
350 * notification when the memory has been touched.
351 * --------------------------------------------------------------------
352 */
353
354struct _ioeventfd {
355 struct list_head list;
356 u64 addr;
357 int length;
358 struct eventfd_ctx *eventfd;
359 u64 datamatch;
360 struct kvm_io_device dev;
361 bool wildcard;
362};
363
364static inline struct _ioeventfd *
365to_ioeventfd(struct kvm_io_device *dev)
366{
367 return container_of(dev, struct _ioeventfd, dev);
368}
369
370static void
371ioeventfd_release(struct _ioeventfd *p)
372{
373 eventfd_ctx_put(p->eventfd);
374 list_del(&p->list);
375 kfree(p);
376}
377
378static bool
379ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
380{
381 u64 _val;
382
383 if (!(addr == p->addr && len == p->length))
384 /* address-range must be precise for a hit */
385 return false;
386
387 if (p->wildcard)
388 /* all else equal, wildcard is always a hit */
389 return true;
390
391 /* otherwise, we have to actually compare the data */
392
393 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
394
395 switch (len) {
396 case 1:
397 _val = *(u8 *)val;
398 break;
399 case 2:
400 _val = *(u16 *)val;
401 break;
402 case 4:
403 _val = *(u32 *)val;
404 break;
405 case 8:
406 _val = *(u64 *)val;
407 break;
408 default:
409 return false;
410 }
411
412 return _val == p->datamatch ? true : false;
413}
414
415/* MMIO/PIO writes trigger an event if the addr/val match */
416static int
417ioeventfd_write(struct kvm_io_device *this, gpa_t addr, int len,
418 const void *val)
419{
420 struct _ioeventfd *p = to_ioeventfd(this);
421
422 if (!ioeventfd_in_range(p, addr, len, val))
423 return -EOPNOTSUPP;
424
425 eventfd_signal(p->eventfd, 1);
426 return 0;
427}
428
429/*
430 * This function is called as KVM is completely shutting down. We do not
431 * need to worry about locking just nuke anything we have as quickly as possible
432 */
433static void
434ioeventfd_destructor(struct kvm_io_device *this)
435{
436 struct _ioeventfd *p = to_ioeventfd(this);
437
438 ioeventfd_release(p);
439}
440
441static const struct kvm_io_device_ops ioeventfd_ops = {
442 .write = ioeventfd_write,
443 .destructor = ioeventfd_destructor,
444};
445
446/* assumes kvm->slots_lock held */
447static bool
448ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
449{
450 struct _ioeventfd *_p;
451
452 list_for_each_entry(_p, &kvm->ioeventfds, list)
453 if (_p->addr == p->addr && _p->length == p->length &&
454 (_p->wildcard || p->wildcard ||
455 _p->datamatch == p->datamatch))
456 return true;
457
458 return false;
459}
460
461static int
462kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
463{
464 int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
Marcelo Tosattie93f8a02009-12-23 14:35:24 -0200465 enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400466 struct _ioeventfd *p;
467 struct eventfd_ctx *eventfd;
468 int ret;
469
470 /* must be natural-word sized */
471 switch (args->len) {
472 case 1:
473 case 2:
474 case 4:
475 case 8:
476 break;
477 default:
478 return -EINVAL;
479 }
480
481 /* check for range overflow */
482 if (args->addr + args->len < args->addr)
483 return -EINVAL;
484
485 /* check for extra flags that we don't understand */
486 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
487 return -EINVAL;
488
489 eventfd = eventfd_ctx_fdget(args->fd);
490 if (IS_ERR(eventfd))
491 return PTR_ERR(eventfd);
492
493 p = kzalloc(sizeof(*p), GFP_KERNEL);
494 if (!p) {
495 ret = -ENOMEM;
496 goto fail;
497 }
498
499 INIT_LIST_HEAD(&p->list);
500 p->addr = args->addr;
501 p->length = args->len;
502 p->eventfd = eventfd;
503
504 /* The datamatch feature is optional, otherwise this is a wildcard */
505 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
506 p->datamatch = args->datamatch;
507 else
508 p->wildcard = true;
509
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200510 mutex_lock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400511
512 /* Verify that there isnt a match already */
513 if (ioeventfd_check_collision(kvm, p)) {
514 ret = -EEXIST;
515 goto unlock_fail;
516 }
517
518 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
519
Marcelo Tosattie93f8a02009-12-23 14:35:24 -0200520 ret = kvm_io_bus_register_dev(kvm, bus_idx, &p->dev);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400521 if (ret < 0)
522 goto unlock_fail;
523
524 list_add_tail(&p->list, &kvm->ioeventfds);
525
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200526 mutex_unlock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400527
528 return 0;
529
530unlock_fail:
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200531 mutex_unlock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400532
533fail:
534 kfree(p);
535 eventfd_ctx_put(eventfd);
536
537 return ret;
538}
539
540static int
541kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
542{
543 int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
Marcelo Tosattie93f8a02009-12-23 14:35:24 -0200544 enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400545 struct _ioeventfd *p, *tmp;
546 struct eventfd_ctx *eventfd;
547 int ret = -ENOENT;
548
549 eventfd = eventfd_ctx_fdget(args->fd);
550 if (IS_ERR(eventfd))
551 return PTR_ERR(eventfd);
552
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200553 mutex_lock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400554
555 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
556 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
557
558 if (p->eventfd != eventfd ||
559 p->addr != args->addr ||
560 p->length != args->len ||
561 p->wildcard != wildcard)
562 continue;
563
564 if (!p->wildcard && p->datamatch != args->datamatch)
565 continue;
566
Marcelo Tosattie93f8a02009-12-23 14:35:24 -0200567 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400568 ioeventfd_release(p);
569 ret = 0;
570 break;
571 }
572
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200573 mutex_unlock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400574
575 eventfd_ctx_put(eventfd);
576
577 return ret;
578}
579
580int
581kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
582{
583 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
584 return kvm_deassign_ioeventfd(kvm, args);
585
586 return kvm_assign_ioeventfd(kvm, args);
587}