blob: bb4ebd89b9fff11ee5a0227bf74805650d9ab4a8 [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.
5 *
6 * Author:
7 * Gregory Haskins <ghaskins@novell.com>
8 *
9 * This file is free software; you can redistribute it and/or modify
10 * it under the terms of version 2 of the GNU General Public License
11 * as published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
21 */
22
23#include <linux/kvm_host.h>
Gregory Haskinsd34e6b12009-07-07 17:08:49 -040024#include <linux/kvm.h>
Gregory Haskins721eecb2009-05-20 10:30:49 -040025#include <linux/workqueue.h>
26#include <linux/syscalls.h>
27#include <linux/wait.h>
28#include <linux/poll.h>
29#include <linux/file.h>
30#include <linux/list.h>
31#include <linux/eventfd.h>
Gregory Haskinsd34e6b12009-07-07 17:08:49 -040032#include <linux/kernel.h>
33
34#include "iodev.h"
Gregory Haskins721eecb2009-05-20 10:30:49 -040035
36/*
37 * --------------------------------------------------------------------
38 * irqfd: Allows an fd to be used to inject an interrupt to the guest
39 *
40 * Credit goes to Avi Kivity for the original idea.
41 * --------------------------------------------------------------------
42 */
43
44struct _irqfd {
45 struct kvm *kvm;
46 struct eventfd_ctx *eventfd;
47 int gsi;
48 struct list_head list;
49 poll_table pt;
50 wait_queue_head_t *wqh;
51 wait_queue_t wait;
52 struct work_struct inject;
53 struct work_struct shutdown;
54};
55
56static struct workqueue_struct *irqfd_cleanup_wq;
57
58static void
59irqfd_inject(struct work_struct *work)
60{
61 struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
62 struct kvm *kvm = irqfd->kvm;
63
Marcelo Tosattifa40a822009-06-04 15:08:24 -030064 mutex_lock(&kvm->irq_lock);
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);
Marcelo Tosattifa40a822009-06-04 15:08:24 -030067 mutex_unlock(&kvm->irq_lock);
Gregory Haskins721eecb2009-05-20 10:30:49 -040068}
69
70/*
71 * Race-free decouple logic (ordering is critical)
72 */
73static void
74irqfd_shutdown(struct work_struct *work)
75{
76 struct _irqfd *irqfd = container_of(work, struct _irqfd, shutdown);
77
78 /*
79 * Synchronize with the wait-queue and unhook ourselves to prevent
80 * further events.
81 */
82 remove_wait_queue(irqfd->wqh, &irqfd->wait);
83
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);
163
164 irqfd->wqh = wqh;
165 add_wait_queue(wqh, &irqfd->wait);
166}
167
168static int
169kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
170{
171 struct _irqfd *irqfd;
172 struct file *file = NULL;
173 struct eventfd_ctx *eventfd = NULL;
174 int ret;
175 unsigned int events;
176
177 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
178 if (!irqfd)
179 return -ENOMEM;
180
181 irqfd->kvm = kvm;
182 irqfd->gsi = gsi;
183 INIT_LIST_HEAD(&irqfd->list);
184 INIT_WORK(&irqfd->inject, irqfd_inject);
185 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
186
187 file = eventfd_fget(fd);
188 if (IS_ERR(file)) {
189 ret = PTR_ERR(file);
190 goto fail;
191 }
192
193 eventfd = eventfd_ctx_fileget(file);
194 if (IS_ERR(eventfd)) {
195 ret = PTR_ERR(eventfd);
196 goto fail;
197 }
198
199 irqfd->eventfd = eventfd;
200
201 /*
202 * Install our own custom wake-up handling so we are notified via
203 * a callback whenever someone signals the underlying eventfd
204 */
205 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
206 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
207
208 events = file->f_op->poll(file, &irqfd->pt);
209
210 spin_lock_irq(&kvm->irqfds.lock);
211 list_add_tail(&irqfd->list, &kvm->irqfds.items);
212 spin_unlock_irq(&kvm->irqfds.lock);
213
214 /*
215 * Check if there was an event already pending on the eventfd
216 * before we registered, and trigger it as if we didn't miss it.
217 */
218 if (events & POLLIN)
219 schedule_work(&irqfd->inject);
220
221 /*
222 * do not drop the file until the irqfd is fully initialized, otherwise
223 * we might race against the POLLHUP
224 */
225 fput(file);
226
227 return 0;
228
229fail:
230 if (eventfd && !IS_ERR(eventfd))
231 eventfd_ctx_put(eventfd);
232
Julia Lawall62230112009-07-28 17:53:24 +0200233 if (!IS_ERR(file))
Gregory Haskins721eecb2009-05-20 10:30:49 -0400234 fput(file);
235
236 kfree(irqfd);
237 return ret;
238}
239
240void
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400241kvm_eventfd_init(struct kvm *kvm)
Gregory Haskins721eecb2009-05-20 10:30:49 -0400242{
243 spin_lock_init(&kvm->irqfds.lock);
244 INIT_LIST_HEAD(&kvm->irqfds.items);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400245 INIT_LIST_HEAD(&kvm->ioeventfds);
Gregory Haskins721eecb2009-05-20 10:30:49 -0400246}
247
248/*
249 * shutdown any irqfd's that match fd+gsi
250 */
251static int
252kvm_irqfd_deassign(struct kvm *kvm, int fd, int gsi)
253{
254 struct _irqfd *irqfd, *tmp;
255 struct eventfd_ctx *eventfd;
256
257 eventfd = eventfd_ctx_fdget(fd);
258 if (IS_ERR(eventfd))
259 return PTR_ERR(eventfd);
260
261 spin_lock_irq(&kvm->irqfds.lock);
262
263 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
264 if (irqfd->eventfd == eventfd && irqfd->gsi == gsi)
265 irqfd_deactivate(irqfd);
266 }
267
268 spin_unlock_irq(&kvm->irqfds.lock);
269 eventfd_ctx_put(eventfd);
270
271 /*
272 * Block until we know all outstanding shutdown jobs have completed
273 * so that we guarantee there will not be any more interrupts on this
274 * gsi once this deassign function returns.
275 */
276 flush_workqueue(irqfd_cleanup_wq);
277
278 return 0;
279}
280
281int
282kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags)
283{
284 if (flags & KVM_IRQFD_FLAG_DEASSIGN)
285 return kvm_irqfd_deassign(kvm, fd, gsi);
286
287 return kvm_irqfd_assign(kvm, fd, gsi);
288}
289
290/*
291 * This function is called as the kvm VM fd is being released. Shutdown all
292 * irqfds that still remain open
293 */
294void
295kvm_irqfd_release(struct kvm *kvm)
296{
297 struct _irqfd *irqfd, *tmp;
298
299 spin_lock_irq(&kvm->irqfds.lock);
300
301 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
302 irqfd_deactivate(irqfd);
303
304 spin_unlock_irq(&kvm->irqfds.lock);
305
306 /*
307 * Block until we know all outstanding shutdown jobs have completed
308 * since we do not take a kvm* reference.
309 */
310 flush_workqueue(irqfd_cleanup_wq);
311
312}
313
314/*
315 * create a host-wide workqueue for issuing deferred shutdown requests
316 * aggregated from all vm* instances. We need our own isolated single-thread
317 * queue to prevent deadlock against flushing the normal work-queue.
318 */
319static int __init irqfd_module_init(void)
320{
321 irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
322 if (!irqfd_cleanup_wq)
323 return -ENOMEM;
324
325 return 0;
326}
327
328static void __exit irqfd_module_exit(void)
329{
330 destroy_workqueue(irqfd_cleanup_wq);
331}
332
333module_init(irqfd_module_init);
334module_exit(irqfd_module_exit);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400335
336/*
337 * --------------------------------------------------------------------
338 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
339 *
340 * userspace can register a PIO/MMIO address with an eventfd for receiving
341 * notification when the memory has been touched.
342 * --------------------------------------------------------------------
343 */
344
345struct _ioeventfd {
346 struct list_head list;
347 u64 addr;
348 int length;
349 struct eventfd_ctx *eventfd;
350 u64 datamatch;
351 struct kvm_io_device dev;
352 bool wildcard;
353};
354
355static inline struct _ioeventfd *
356to_ioeventfd(struct kvm_io_device *dev)
357{
358 return container_of(dev, struct _ioeventfd, dev);
359}
360
361static void
362ioeventfd_release(struct _ioeventfd *p)
363{
364 eventfd_ctx_put(p->eventfd);
365 list_del(&p->list);
366 kfree(p);
367}
368
369static bool
370ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
371{
372 u64 _val;
373
374 if (!(addr == p->addr && len == p->length))
375 /* address-range must be precise for a hit */
376 return false;
377
378 if (p->wildcard)
379 /* all else equal, wildcard is always a hit */
380 return true;
381
382 /* otherwise, we have to actually compare the data */
383
384 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
385
386 switch (len) {
387 case 1:
388 _val = *(u8 *)val;
389 break;
390 case 2:
391 _val = *(u16 *)val;
392 break;
393 case 4:
394 _val = *(u32 *)val;
395 break;
396 case 8:
397 _val = *(u64 *)val;
398 break;
399 default:
400 return false;
401 }
402
403 return _val == p->datamatch ? true : false;
404}
405
406/* MMIO/PIO writes trigger an event if the addr/val match */
407static int
408ioeventfd_write(struct kvm_io_device *this, gpa_t addr, int len,
409 const void *val)
410{
411 struct _ioeventfd *p = to_ioeventfd(this);
412
413 if (!ioeventfd_in_range(p, addr, len, val))
414 return -EOPNOTSUPP;
415
416 eventfd_signal(p->eventfd, 1);
417 return 0;
418}
419
420/*
421 * This function is called as KVM is completely shutting down. We do not
422 * need to worry about locking just nuke anything we have as quickly as possible
423 */
424static void
425ioeventfd_destructor(struct kvm_io_device *this)
426{
427 struct _ioeventfd *p = to_ioeventfd(this);
428
429 ioeventfd_release(p);
430}
431
432static const struct kvm_io_device_ops ioeventfd_ops = {
433 .write = ioeventfd_write,
434 .destructor = ioeventfd_destructor,
435};
436
437/* assumes kvm->slots_lock held */
438static bool
439ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
440{
441 struct _ioeventfd *_p;
442
443 list_for_each_entry(_p, &kvm->ioeventfds, list)
444 if (_p->addr == p->addr && _p->length == p->length &&
445 (_p->wildcard || p->wildcard ||
446 _p->datamatch == p->datamatch))
447 return true;
448
449 return false;
450}
451
452static int
453kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
454{
455 int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
456 struct kvm_io_bus *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus;
457 struct _ioeventfd *p;
458 struct eventfd_ctx *eventfd;
459 int ret;
460
461 /* must be natural-word sized */
462 switch (args->len) {
463 case 1:
464 case 2:
465 case 4:
466 case 8:
467 break;
468 default:
469 return -EINVAL;
470 }
471
472 /* check for range overflow */
473 if (args->addr + args->len < args->addr)
474 return -EINVAL;
475
476 /* check for extra flags that we don't understand */
477 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
478 return -EINVAL;
479
480 eventfd = eventfd_ctx_fdget(args->fd);
481 if (IS_ERR(eventfd))
482 return PTR_ERR(eventfd);
483
484 p = kzalloc(sizeof(*p), GFP_KERNEL);
485 if (!p) {
486 ret = -ENOMEM;
487 goto fail;
488 }
489
490 INIT_LIST_HEAD(&p->list);
491 p->addr = args->addr;
492 p->length = args->len;
493 p->eventfd = eventfd;
494
495 /* The datamatch feature is optional, otherwise this is a wildcard */
496 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
497 p->datamatch = args->datamatch;
498 else
499 p->wildcard = true;
500
501 down_write(&kvm->slots_lock);
502
503 /* Verify that there isnt a match already */
504 if (ioeventfd_check_collision(kvm, p)) {
505 ret = -EEXIST;
506 goto unlock_fail;
507 }
508
509 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
510
511 ret = __kvm_io_bus_register_dev(bus, &p->dev);
512 if (ret < 0)
513 goto unlock_fail;
514
515 list_add_tail(&p->list, &kvm->ioeventfds);
516
517 up_write(&kvm->slots_lock);
518
519 return 0;
520
521unlock_fail:
522 up_write(&kvm->slots_lock);
523
524fail:
525 kfree(p);
526 eventfd_ctx_put(eventfd);
527
528 return ret;
529}
530
531static int
532kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
533{
534 int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
535 struct kvm_io_bus *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus;
536 struct _ioeventfd *p, *tmp;
537 struct eventfd_ctx *eventfd;
538 int ret = -ENOENT;
539
540 eventfd = eventfd_ctx_fdget(args->fd);
541 if (IS_ERR(eventfd))
542 return PTR_ERR(eventfd);
543
544 down_write(&kvm->slots_lock);
545
546 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
547 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
548
549 if (p->eventfd != eventfd ||
550 p->addr != args->addr ||
551 p->length != args->len ||
552 p->wildcard != wildcard)
553 continue;
554
555 if (!p->wildcard && p->datamatch != args->datamatch)
556 continue;
557
558 __kvm_io_bus_unregister_dev(bus, &p->dev);
559 ioeventfd_release(p);
560 ret = 0;
561 break;
562 }
563
564 up_write(&kvm->slots_lock);
565
566 eventfd_ctx_put(eventfd);
567
568 return ret;
569}
570
571int
572kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
573{
574 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
575 return kvm_deassign_ioeventfd(kvm, args);
576
577 return kvm_assign_ioeventfd(kvm, args);
578}