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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);
Gregory Haskins721eecb2009-05-20 10:30:49 -0400221
222 /*
223 * Check if there was an event already pending on the eventfd
224 * before we registered, and trigger it as if we didn't miss it.
225 */
226 if (events & POLLIN)
227 schedule_work(&irqfd->inject);
228
Michael S. Tsirkin6bbfb262010-09-19 19:02:31 +0200229 spin_unlock_irq(&kvm->irqfds.lock);
230
Gregory Haskins721eecb2009-05-20 10:30:49 -0400231 /*
232 * do not drop the file until the irqfd is fully initialized, otherwise
233 * we might race against the POLLHUP
234 */
235 fput(file);
236
237 return 0;
238
239fail:
240 if (eventfd && !IS_ERR(eventfd))
241 eventfd_ctx_put(eventfd);
242
Julia Lawall62230112009-07-28 17:53:24 +0200243 if (!IS_ERR(file))
Gregory Haskins721eecb2009-05-20 10:30:49 -0400244 fput(file);
245
246 kfree(irqfd);
247 return ret;
248}
249
250void
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400251kvm_eventfd_init(struct kvm *kvm)
Gregory Haskins721eecb2009-05-20 10:30:49 -0400252{
253 spin_lock_init(&kvm->irqfds.lock);
254 INIT_LIST_HEAD(&kvm->irqfds.items);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400255 INIT_LIST_HEAD(&kvm->ioeventfds);
Gregory Haskins721eecb2009-05-20 10:30:49 -0400256}
257
258/*
259 * shutdown any irqfd's that match fd+gsi
260 */
261static int
262kvm_irqfd_deassign(struct kvm *kvm, int fd, int gsi)
263{
264 struct _irqfd *irqfd, *tmp;
265 struct eventfd_ctx *eventfd;
266
267 eventfd = eventfd_ctx_fdget(fd);
268 if (IS_ERR(eventfd))
269 return PTR_ERR(eventfd);
270
271 spin_lock_irq(&kvm->irqfds.lock);
272
273 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
274 if (irqfd->eventfd == eventfd && irqfd->gsi == gsi)
275 irqfd_deactivate(irqfd);
276 }
277
278 spin_unlock_irq(&kvm->irqfds.lock);
279 eventfd_ctx_put(eventfd);
280
281 /*
282 * Block until we know all outstanding shutdown jobs have completed
283 * so that we guarantee there will not be any more interrupts on this
284 * gsi once this deassign function returns.
285 */
286 flush_workqueue(irqfd_cleanup_wq);
287
288 return 0;
289}
290
291int
292kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags)
293{
294 if (flags & KVM_IRQFD_FLAG_DEASSIGN)
295 return kvm_irqfd_deassign(kvm, fd, gsi);
296
297 return kvm_irqfd_assign(kvm, fd, gsi);
298}
299
300/*
301 * This function is called as the kvm VM fd is being released. Shutdown all
302 * irqfds that still remain open
303 */
304void
305kvm_irqfd_release(struct kvm *kvm)
306{
307 struct _irqfd *irqfd, *tmp;
308
309 spin_lock_irq(&kvm->irqfds.lock);
310
311 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
312 irqfd_deactivate(irqfd);
313
314 spin_unlock_irq(&kvm->irqfds.lock);
315
316 /*
317 * Block until we know all outstanding shutdown jobs have completed
318 * since we do not take a kvm* reference.
319 */
320 flush_workqueue(irqfd_cleanup_wq);
321
322}
323
324/*
325 * create a host-wide workqueue for issuing deferred shutdown requests
326 * aggregated from all vm* instances. We need our own isolated single-thread
327 * queue to prevent deadlock against flushing the normal work-queue.
328 */
329static int __init irqfd_module_init(void)
330{
331 irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
332 if (!irqfd_cleanup_wq)
333 return -ENOMEM;
334
335 return 0;
336}
337
338static void __exit irqfd_module_exit(void)
339{
340 destroy_workqueue(irqfd_cleanup_wq);
341}
342
343module_init(irqfd_module_init);
344module_exit(irqfd_module_exit);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400345
346/*
347 * --------------------------------------------------------------------
348 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
349 *
350 * userspace can register a PIO/MMIO address with an eventfd for receiving
351 * notification when the memory has been touched.
352 * --------------------------------------------------------------------
353 */
354
355struct _ioeventfd {
356 struct list_head list;
357 u64 addr;
358 int length;
359 struct eventfd_ctx *eventfd;
360 u64 datamatch;
361 struct kvm_io_device dev;
362 bool wildcard;
363};
364
365static inline struct _ioeventfd *
366to_ioeventfd(struct kvm_io_device *dev)
367{
368 return container_of(dev, struct _ioeventfd, dev);
369}
370
371static void
372ioeventfd_release(struct _ioeventfd *p)
373{
374 eventfd_ctx_put(p->eventfd);
375 list_del(&p->list);
376 kfree(p);
377}
378
379static bool
380ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
381{
382 u64 _val;
383
384 if (!(addr == p->addr && len == p->length))
385 /* address-range must be precise for a hit */
386 return false;
387
388 if (p->wildcard)
389 /* all else equal, wildcard is always a hit */
390 return true;
391
392 /* otherwise, we have to actually compare the data */
393
394 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
395
396 switch (len) {
397 case 1:
398 _val = *(u8 *)val;
399 break;
400 case 2:
401 _val = *(u16 *)val;
402 break;
403 case 4:
404 _val = *(u32 *)val;
405 break;
406 case 8:
407 _val = *(u64 *)val;
408 break;
409 default:
410 return false;
411 }
412
413 return _val == p->datamatch ? true : false;
414}
415
416/* MMIO/PIO writes trigger an event if the addr/val match */
417static int
418ioeventfd_write(struct kvm_io_device *this, gpa_t addr, int len,
419 const void *val)
420{
421 struct _ioeventfd *p = to_ioeventfd(this);
422
423 if (!ioeventfd_in_range(p, addr, len, val))
424 return -EOPNOTSUPP;
425
426 eventfd_signal(p->eventfd, 1);
427 return 0;
428}
429
430/*
431 * This function is called as KVM is completely shutting down. We do not
432 * need to worry about locking just nuke anything we have as quickly as possible
433 */
434static void
435ioeventfd_destructor(struct kvm_io_device *this)
436{
437 struct _ioeventfd *p = to_ioeventfd(this);
438
439 ioeventfd_release(p);
440}
441
442static const struct kvm_io_device_ops ioeventfd_ops = {
443 .write = ioeventfd_write,
444 .destructor = ioeventfd_destructor,
445};
446
447/* assumes kvm->slots_lock held */
448static bool
449ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
450{
451 struct _ioeventfd *_p;
452
453 list_for_each_entry(_p, &kvm->ioeventfds, list)
454 if (_p->addr == p->addr && _p->length == p->length &&
455 (_p->wildcard || p->wildcard ||
456 _p->datamatch == p->datamatch))
457 return true;
458
459 return false;
460}
461
462static int
463kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
464{
465 int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
Marcelo Tosattie93f8a02009-12-23 14:35:24 -0200466 enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400467 struct _ioeventfd *p;
468 struct eventfd_ctx *eventfd;
469 int ret;
470
471 /* must be natural-word sized */
472 switch (args->len) {
473 case 1:
474 case 2:
475 case 4:
476 case 8:
477 break;
478 default:
479 return -EINVAL;
480 }
481
482 /* check for range overflow */
483 if (args->addr + args->len < args->addr)
484 return -EINVAL;
485
486 /* check for extra flags that we don't understand */
487 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
488 return -EINVAL;
489
490 eventfd = eventfd_ctx_fdget(args->fd);
491 if (IS_ERR(eventfd))
492 return PTR_ERR(eventfd);
493
494 p = kzalloc(sizeof(*p), GFP_KERNEL);
495 if (!p) {
496 ret = -ENOMEM;
497 goto fail;
498 }
499
500 INIT_LIST_HEAD(&p->list);
501 p->addr = args->addr;
502 p->length = args->len;
503 p->eventfd = eventfd;
504
505 /* The datamatch feature is optional, otherwise this is a wildcard */
506 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
507 p->datamatch = args->datamatch;
508 else
509 p->wildcard = true;
510
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200511 mutex_lock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400512
513 /* Verify that there isnt a match already */
514 if (ioeventfd_check_collision(kvm, p)) {
515 ret = -EEXIST;
516 goto unlock_fail;
517 }
518
519 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
520
Marcelo Tosattie93f8a02009-12-23 14:35:24 -0200521 ret = kvm_io_bus_register_dev(kvm, bus_idx, &p->dev);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400522 if (ret < 0)
523 goto unlock_fail;
524
525 list_add_tail(&p->list, &kvm->ioeventfds);
526
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200527 mutex_unlock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400528
529 return 0;
530
531unlock_fail:
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200532 mutex_unlock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400533
534fail:
535 kfree(p);
536 eventfd_ctx_put(eventfd);
537
538 return ret;
539}
540
541static int
542kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
543{
544 int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
Marcelo Tosattie93f8a02009-12-23 14:35:24 -0200545 enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400546 struct _ioeventfd *p, *tmp;
547 struct eventfd_ctx *eventfd;
548 int ret = -ENOENT;
549
550 eventfd = eventfd_ctx_fdget(args->fd);
551 if (IS_ERR(eventfd))
552 return PTR_ERR(eventfd);
553
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200554 mutex_lock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400555
556 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
557 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
558
559 if (p->eventfd != eventfd ||
560 p->addr != args->addr ||
561 p->length != args->len ||
562 p->wildcard != wildcard)
563 continue;
564
565 if (!p->wildcard && p->datamatch != args->datamatch)
566 continue;
567
Marcelo Tosattie93f8a02009-12-23 14:35:24 -0200568 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400569 ioeventfd_release(p);
570 ret = 0;
571 break;
572 }
573
Marcelo Tosatti79fac952009-12-23 14:35:26 -0200574 mutex_unlock(&kvm->slots_lock);
Gregory Haskinsd34e6b12009-07-07 17:08:49 -0400575
576 eventfd_ctx_put(eventfd);
577
578 return ret;
579}
580
581int
582kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
583{
584 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
585 return kvm_deassign_ioeventfd(kvm, args);
586
587 return kvm_assign_ioeventfd(kvm, args);
588}