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x86/xen: resume timer irqs early
[linux/fpc-iii.git] / drivers / vhost / vhost.c
blob69068e0d8f31af183c075afe3026d60b09a0b55e
1 /* Copyright (C) 2009 Red Hat, Inc.
2 * Copyright (C) 2006 Rusty Russell IBM Corporation
3 *
4 * Author: Michael S. Tsirkin <mst@redhat.com>
5 *
6 * Inspiration, some code, and most witty comments come from
7 * Documentation/virtual/lguest/lguest.c, by Rusty Russell
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2.
10 *
11 * Generic code for virtio server in host kernel.
12 */
13
14 #include <linux/eventfd.h>
15 #include <linux/vhost.h>
16 #include <linux/uio.h>
17 #include <linux/mm.h>
18 #include <linux/mmu_context.h>
19 #include <linux/miscdevice.h>
20 #include <linux/mutex.h>
21 #include <linux/rcupdate.h>
22 #include <linux/poll.h>
23 #include <linux/file.h>
24 #include <linux/highmem.h>
25 #include <linux/slab.h>
26 #include <linux/kthread.h>
27 #include <linux/cgroup.h>
28 #include <linux/module.h>
29
30 #include "vhost.h"
31
32 enum {
33 VHOST_MEMORY_MAX_NREGIONS = 64,
34 VHOST_MEMORY_F_LOG = 0x1,
35 };
36
37 #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
38 #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
39
40 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
41 poll_table *pt)
42 {
43 struct vhost_poll *poll;
44
45 poll = container_of(pt, struct vhost_poll, table);
46 poll->wqh = wqh;
47 add_wait_queue(wqh, &poll->wait);
48 }
49
50 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
51 void *key)
52 {
53 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
54
55 if (!((unsigned long)key & poll->mask))
56 return 0;
57
58 vhost_poll_queue(poll);
59 return 0;
60 }
61
62 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
63 {
64 INIT_LIST_HEAD(&work->node);
65 work->fn = fn;
66 init_waitqueue_head(&work->done);
67 work->flushing = 0;
68 work->queue_seq = work->done_seq = 0;
69 }
70 EXPORT_SYMBOL_GPL(vhost_work_init);
71
72 /* Init poll structure */
73 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
74 unsigned long mask, struct vhost_dev *dev)
75 {
76 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
77 init_poll_funcptr(&poll->table, vhost_poll_func);
78 poll->mask = mask;
79 poll->dev = dev;
80 poll->wqh = NULL;
81
82 vhost_work_init(&poll->work, fn);
83 }
84 EXPORT_SYMBOL_GPL(vhost_poll_init);
85
86 /* Start polling a file. We add ourselves to file's wait queue. The caller must
87 * keep a reference to a file until after vhost_poll_stop is called. */
88 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
89 {
90 unsigned long mask;
91 int ret = 0;
92
93 if (poll->wqh)
94 return 0;
95
96 mask = file->f_op->poll(file, &poll->table);
97 if (mask)
98 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
99 if (mask & POLLERR) {
100 if (poll->wqh)
101 remove_wait_queue(poll->wqh, &poll->wait);
102 ret = -EINVAL;
103 }
104
105 return ret;
106 }
107 EXPORT_SYMBOL_GPL(vhost_poll_start);
108
109 /* Stop polling a file. After this function returns, it becomes safe to drop the
110 * file reference. You must also flush afterwards. */
111 void vhost_poll_stop(struct vhost_poll *poll)
112 {
113 if (poll->wqh) {
114 remove_wait_queue(poll->wqh, &poll->wait);
115 poll->wqh = NULL;
116 }
117 }
118 EXPORT_SYMBOL_GPL(vhost_poll_stop);
119
120 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
121 unsigned seq)
122 {
123 int left;
124
125 spin_lock_irq(&dev->work_lock);
126 left = seq - work->done_seq;
127 spin_unlock_irq(&dev->work_lock);
128 return left <= 0;
129 }
130
131 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
132 {
133 unsigned seq;
134 int flushing;
135
136 spin_lock_irq(&dev->work_lock);
137 seq = work->queue_seq;
138 work->flushing++;
139 spin_unlock_irq(&dev->work_lock);
140 wait_event(work->done, vhost_work_seq_done(dev, work, seq));
141 spin_lock_irq(&dev->work_lock);
142 flushing = --work->flushing;
143 spin_unlock_irq(&dev->work_lock);
144 BUG_ON(flushing < 0);
145 }
146 EXPORT_SYMBOL_GPL(vhost_work_flush);
147
148 /* Flush any work that has been scheduled. When calling this, don't hold any
149 * locks that are also used by the callback. */
150 void vhost_poll_flush(struct vhost_poll *poll)
151 {
152 vhost_work_flush(poll->dev, &poll->work);
153 }
154 EXPORT_SYMBOL_GPL(vhost_poll_flush);
155
156 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
157 {
158 unsigned long flags;
159
160 spin_lock_irqsave(&dev->work_lock, flags);
161 if (list_empty(&work->node)) {
162 list_add_tail(&work->node, &dev->work_list);
163 work->queue_seq++;
164 spin_unlock_irqrestore(&dev->work_lock, flags);
165 wake_up_process(dev->worker);
166 } else {
167 spin_unlock_irqrestore(&dev->work_lock, flags);
168 }
169 }
170 EXPORT_SYMBOL_GPL(vhost_work_queue);
171
172 void vhost_poll_queue(struct vhost_poll *poll)
173 {
174 vhost_work_queue(poll->dev, &poll->work);
175 }
176 EXPORT_SYMBOL_GPL(vhost_poll_queue);
177
178 static void vhost_vq_reset(struct vhost_dev *dev,
179 struct vhost_virtqueue *vq)
180 {
181 vq->num = 1;
182 vq->desc = NULL;
183 vq->avail = NULL;
184 vq->used = NULL;
185 vq->last_avail_idx = 0;
186 vq->avail_idx = 0;
187 vq->last_used_idx = 0;
188 vq->signalled_used = 0;
189 vq->signalled_used_valid = false;
190 vq->used_flags = 0;
191 vq->log_used = false;
192 vq->log_addr = -1ull;
193 vq->private_data = NULL;
194 vq->log_base = NULL;
195 vq->error_ctx = NULL;
196 vq->error = NULL;
197 vq->kick = NULL;
198 vq->call_ctx = NULL;
199 vq->call = NULL;
200 vq->log_ctx = NULL;
201 }
202
203 static int vhost_worker(void *data)
204 {
205 struct vhost_dev *dev = data;
206 struct vhost_work *work = NULL;
207 unsigned uninitialized_var(seq);
208 mm_segment_t oldfs = get_fs();
209
210 set_fs(USER_DS);
211 use_mm(dev->mm);
212
213 for (;;) {
214 /* mb paired w/ kthread_stop */
215 set_current_state(TASK_INTERRUPTIBLE);
216
217 spin_lock_irq(&dev->work_lock);
218 if (work) {
219 work->done_seq = seq;
220 if (work->flushing)
221 wake_up_all(&work->done);
222 }
223
224 if (kthread_should_stop()) {
225 spin_unlock_irq(&dev->work_lock);
226 __set_current_state(TASK_RUNNING);
227 break;
228 }
229 if (!list_empty(&dev->work_list)) {
230 work = list_first_entry(&dev->work_list,
231 struct vhost_work, node);
232 list_del_init(&work->node);
233 seq = work->queue_seq;
234 } else
235 work = NULL;
236 spin_unlock_irq(&dev->work_lock);
237
238 if (work) {
239 __set_current_state(TASK_RUNNING);
240 work->fn(work);
241 if (need_resched())
242 schedule();
243 } else
244 schedule();
245
246 }
247 unuse_mm(dev->mm);
248 set_fs(oldfs);
249 return 0;
250 }
251
252 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
253 {
254 kfree(vq->indirect);
255 vq->indirect = NULL;
256 kfree(vq->log);
257 vq->log = NULL;
258 kfree(vq->heads);
259 vq->heads = NULL;
260 }
261
262 /* Helper to allocate iovec buffers for all vqs. */
263 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
264 {
265 struct vhost_virtqueue *vq;
266 int i;
267
268 for (i = 0; i < dev->nvqs; ++i) {
269 vq = dev->vqs[i];
270 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
271 GFP_KERNEL);
272 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
273 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
274 if (!vq->indirect || !vq->log || !vq->heads)
275 goto err_nomem;
276 }
277 return 0;
278
279 err_nomem:
280 for (; i >= 0; --i)
281 vhost_vq_free_iovecs(dev->vqs[i]);
282 return -ENOMEM;
283 }
284
285 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
286 {
287 int i;
288
289 for (i = 0; i < dev->nvqs; ++i)
290 vhost_vq_free_iovecs(dev->vqs[i]);
291 }
292
293 long vhost_dev_init(struct vhost_dev *dev,
294 struct vhost_virtqueue **vqs, int nvqs)
295 {
296 struct vhost_virtqueue *vq;
297 int i;
298
299 dev->vqs = vqs;
300 dev->nvqs = nvqs;
301 mutex_init(&dev->mutex);
302 dev->log_ctx = NULL;
303 dev->log_file = NULL;
304 dev->memory = NULL;
305 dev->mm = NULL;
306 spin_lock_init(&dev->work_lock);
307 INIT_LIST_HEAD(&dev->work_list);
308 dev->worker = NULL;
309
310 for (i = 0; i < dev->nvqs; ++i) {
311 vq = dev->vqs[i];
312 vq->log = NULL;
313 vq->indirect = NULL;
314 vq->heads = NULL;
315 vq->dev = dev;
316 mutex_init(&vq->mutex);
317 vhost_vq_reset(dev, vq);
318 if (vq->handle_kick)
319 vhost_poll_init(&vq->poll, vq->handle_kick,
320 POLLIN, dev);
321 }
322
323 return 0;
324 }
325 EXPORT_SYMBOL_GPL(vhost_dev_init);
326
327 /* Caller should have device mutex */
328 long vhost_dev_check_owner(struct vhost_dev *dev)
329 {
330 /* Are you the owner? If not, I don't think you mean to do that */
331 return dev->mm == current->mm ? 0 : -EPERM;
332 }
333 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
334
335 struct vhost_attach_cgroups_struct {
336 struct vhost_work work;
337 struct task_struct *owner;
338 int ret;
339 };
340
341 static void vhost_attach_cgroups_work(struct vhost_work *work)
342 {
343 struct vhost_attach_cgroups_struct *s;
344
345 s = container_of(work, struct vhost_attach_cgroups_struct, work);
346 s->ret = cgroup_attach_task_all(s->owner, current);
347 }
348
349 static int vhost_attach_cgroups(struct vhost_dev *dev)
350 {
351 struct vhost_attach_cgroups_struct attach;
352
353 attach.owner = current;
354 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
355 vhost_work_queue(dev, &attach.work);
356 vhost_work_flush(dev, &attach.work);
357 return attach.ret;
358 }
359
360 /* Caller should have device mutex */
361 bool vhost_dev_has_owner(struct vhost_dev *dev)
362 {
363 return dev->mm;
364 }
365 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
366
367 /* Caller should have device mutex */
368 long vhost_dev_set_owner(struct vhost_dev *dev)
369 {
370 struct task_struct *worker;
371 int err;
372
373 /* Is there an owner already? */
374 if (vhost_dev_has_owner(dev)) {
375 err = -EBUSY;
376 goto err_mm;
377 }
378
379 /* No owner, become one */
380 dev->mm = get_task_mm(current);
381 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
382 if (IS_ERR(worker)) {
383 err = PTR_ERR(worker);
384 goto err_worker;
385 }
386
387 dev->worker = worker;
388 wake_up_process(worker); /* avoid contributing to loadavg */
389
390 err = vhost_attach_cgroups(dev);
391 if (err)
392 goto err_cgroup;
393
394 err = vhost_dev_alloc_iovecs(dev);
395 if (err)
396 goto err_cgroup;
397
398 return 0;
399 err_cgroup:
400 kthread_stop(worker);
401 dev->worker = NULL;
402 err_worker:
403 if (dev->mm)
404 mmput(dev->mm);
405 dev->mm = NULL;
406 err_mm:
407 return err;
408 }
409 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
410
411 struct vhost_memory *vhost_dev_reset_owner_prepare(void)
412 {
413 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
414 }
415 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
416
417 /* Caller should have device mutex */
418 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory)
419 {
420 vhost_dev_cleanup(dev, true);
421
422 /* Restore memory to default empty mapping. */
423 memory->nregions = 0;
424 RCU_INIT_POINTER(dev->memory, memory);
425 }
426 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
427
428 void vhost_dev_stop(struct vhost_dev *dev)
429 {
430 int i;
431
432 for (i = 0; i < dev->nvqs; ++i) {
433 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
434 vhost_poll_stop(&dev->vqs[i]->poll);
435 vhost_poll_flush(&dev->vqs[i]->poll);
436 }
437 }
438 }
439 EXPORT_SYMBOL_GPL(vhost_dev_stop);
440
441 /* Caller should have device mutex if and only if locked is set */
442 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
443 {
444 int i;
445
446 for (i = 0; i < dev->nvqs; ++i) {
447 if (dev->vqs[i]->error_ctx)
448 eventfd_ctx_put(dev->vqs[i]->error_ctx);
449 if (dev->vqs[i]->error)
450 fput(dev->vqs[i]->error);
451 if (dev->vqs[i]->kick)
452 fput(dev->vqs[i]->kick);
453 if (dev->vqs[i]->call_ctx)
454 eventfd_ctx_put(dev->vqs[i]->call_ctx);
455 if (dev->vqs[i]->call)
456 fput(dev->vqs[i]->call);
457 vhost_vq_reset(dev, dev->vqs[i]);
458 }
459 vhost_dev_free_iovecs(dev);
460 if (dev->log_ctx)
461 eventfd_ctx_put(dev->log_ctx);
462 dev->log_ctx = NULL;
463 if (dev->log_file)
464 fput(dev->log_file);
465 dev->log_file = NULL;
466 /* No one will access memory at this point */
467 kfree(rcu_dereference_protected(dev->memory,
468 locked ==
469 lockdep_is_held(&dev->mutex)));
470 RCU_INIT_POINTER(dev->memory, NULL);
471 WARN_ON(!list_empty(&dev->work_list));
472 if (dev->worker) {
473 kthread_stop(dev->worker);
474 dev->worker = NULL;
475 }
476 if (dev->mm)
477 mmput(dev->mm);
478 dev->mm = NULL;
479 }
480 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
481
482 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
483 {
484 u64 a = addr / VHOST_PAGE_SIZE / 8;
485
486 /* Make sure 64 bit math will not overflow. */
487 if (a > ULONG_MAX - (unsigned long)log_base ||
488 a + (unsigned long)log_base > ULONG_MAX)
489 return 0;
490
491 return access_ok(VERIFY_WRITE, log_base + a,
492 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
493 }
494
495 /* Caller should have vq mutex and device mutex. */
496 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
497 int log_all)
498 {
499 int i;
500
501 if (!mem)
502 return 0;
503
504 for (i = 0; i < mem->nregions; ++i) {
505 struct vhost_memory_region *m = mem->regions + i;
506 unsigned long a = m->userspace_addr;
507 if (m->memory_size > ULONG_MAX)
508 return 0;
509 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
510 m->memory_size))
511 return 0;
512 else if (log_all && !log_access_ok(log_base,
513 m->guest_phys_addr,
514 m->memory_size))
515 return 0;
516 }
517 return 1;
518 }
519
520 /* Can we switch to this memory table? */
521 /* Caller should have device mutex but not vq mutex */
522 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
523 int log_all)
524 {
525 int i;
526
527 for (i = 0; i < d->nvqs; ++i) {
528 int ok;
529 mutex_lock(&d->vqs[i]->mutex);
530 /* If ring is inactive, will check when it's enabled. */
531 if (d->vqs[i]->private_data)
532 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem,
533 log_all);
534 else
535 ok = 1;
536 mutex_unlock(&d->vqs[i]->mutex);
537 if (!ok)
538 return 0;
539 }
540 return 1;
541 }
542
543 static int vq_access_ok(struct vhost_dev *d, unsigned int num,
544 struct vring_desc __user *desc,
545 struct vring_avail __user *avail,
546 struct vring_used __user *used)
547 {
548 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
549 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
550 access_ok(VERIFY_READ, avail,
551 sizeof *avail + num * sizeof *avail->ring + s) &&
552 access_ok(VERIFY_WRITE, used,
553 sizeof *used + num * sizeof *used->ring + s);
554 }
555
556 /* Can we log writes? */
557 /* Caller should have device mutex but not vq mutex */
558 int vhost_log_access_ok(struct vhost_dev *dev)
559 {
560 struct vhost_memory *mp;
561
562 mp = rcu_dereference_protected(dev->memory,
563 lockdep_is_held(&dev->mutex));
564 return memory_access_ok(dev, mp, 1);
565 }
566 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
567
568 /* Verify access for write logging. */
569 /* Caller should have vq mutex and device mutex */
570 static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
571 void __user *log_base)
572 {
573 struct vhost_memory *mp;
574 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
575
576 mp = rcu_dereference_protected(vq->dev->memory,
577 lockdep_is_held(&vq->mutex));
578 return vq_memory_access_ok(log_base, mp,
579 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
580 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
581 sizeof *vq->used +
582 vq->num * sizeof *vq->used->ring + s));
583 }
584
585 /* Can we start vq? */
586 /* Caller should have vq mutex and device mutex */
587 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
588 {
589 return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
590 vq_log_access_ok(vq->dev, vq, vq->log_base);
591 }
592 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
593
594 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
595 {
596 struct vhost_memory mem, *newmem, *oldmem;
597 unsigned long size = offsetof(struct vhost_memory, regions);
598
599 if (copy_from_user(&mem, m, size))
600 return -EFAULT;
601 if (mem.padding)
602 return -EOPNOTSUPP;
603 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
604 return -E2BIG;
605 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL);
606 if (!newmem)
607 return -ENOMEM;
608
609 memcpy(newmem, &mem, size);
610 if (copy_from_user(newmem->regions, m->regions,
611 mem.nregions * sizeof *m->regions)) {
612 kfree(newmem);
613 return -EFAULT;
614 }
615
616 if (!memory_access_ok(d, newmem,
617 vhost_has_feature(d, VHOST_F_LOG_ALL))) {
618 kfree(newmem);
619 return -EFAULT;
620 }
621 oldmem = rcu_dereference_protected(d->memory,
622 lockdep_is_held(&d->mutex));
623 rcu_assign_pointer(d->memory, newmem);
624 synchronize_rcu();
625 kfree(oldmem);
626 return 0;
627 }
628
629 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
630 {
631 struct file *eventfp, *filep = NULL;
632 bool pollstart = false, pollstop = false;
633 struct eventfd_ctx *ctx = NULL;
634 u32 __user *idxp = argp;
635 struct vhost_virtqueue *vq;
636 struct vhost_vring_state s;
637 struct vhost_vring_file f;
638 struct vhost_vring_addr a;
639 u32 idx;
640 long r;
641
642 r = get_user(idx, idxp);
643 if (r < 0)
644 return r;
645 if (idx >= d->nvqs)
646 return -ENOBUFS;
647
648 vq = d->vqs[idx];
649
650 mutex_lock(&vq->mutex);
651
652 switch (ioctl) {
653 case VHOST_SET_VRING_NUM:
654 /* Resizing ring with an active backend?
655 * You don't want to do that. */
656 if (vq->private_data) {
657 r = -EBUSY;
658 break;
659 }
660 if (copy_from_user(&s, argp, sizeof s)) {
661 r = -EFAULT;
662 break;
663 }
664 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
665 r = -EINVAL;
666 break;
667 }
668 vq->num = s.num;
669 break;
670 case VHOST_SET_VRING_BASE:
671 /* Moving base with an active backend?
672 * You don't want to do that. */
673 if (vq->private_data) {
674 r = -EBUSY;
675 break;
676 }
677 if (copy_from_user(&s, argp, sizeof s)) {
678 r = -EFAULT;
679 break;
680 }
681 if (s.num > 0xffff) {
682 r = -EINVAL;
683 break;
684 }
685 vq->last_avail_idx = s.num;
686 /* Forget the cached index value. */
687 vq->avail_idx = vq->last_avail_idx;
688 break;
689 case VHOST_GET_VRING_BASE:
690 s.index = idx;
691 s.num = vq->last_avail_idx;
692 if (copy_to_user(argp, &s, sizeof s))
693 r = -EFAULT;
694 break;
695 case VHOST_SET_VRING_ADDR:
696 if (copy_from_user(&a, argp, sizeof a)) {
697 r = -EFAULT;
698 break;
699 }
700 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
701 r = -EOPNOTSUPP;
702 break;
703 }
704 /* For 32bit, verify that the top 32bits of the user
705 data are set to zero. */
706 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
707 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
708 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
709 r = -EFAULT;
710 break;
711 }
712 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
713 (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
714 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
715 r = -EINVAL;
716 break;
717 }
718
719 /* We only verify access here if backend is configured.
720 * If it is not, we don't as size might not have been setup.
721 * We will verify when backend is configured. */
722 if (vq->private_data) {
723 if (!vq_access_ok(d, vq->num,
724 (void __user *)(unsigned long)a.desc_user_addr,
725 (void __user *)(unsigned long)a.avail_user_addr,
726 (void __user *)(unsigned long)a.used_user_addr)) {
727 r = -EINVAL;
728 break;
729 }
730
731 /* Also validate log access for used ring if enabled. */
732 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
733 !log_access_ok(vq->log_base, a.log_guest_addr,
734 sizeof *vq->used +
735 vq->num * sizeof *vq->used->ring)) {
736 r = -EINVAL;
737 break;
738 }
739 }
740
741 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
742 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
743 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
744 vq->log_addr = a.log_guest_addr;
745 vq->used = (void __user *)(unsigned long)a.used_user_addr;
746 break;
747 case VHOST_SET_VRING_KICK:
748 if (copy_from_user(&f, argp, sizeof f)) {
749 r = -EFAULT;
750 break;
751 }
752 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
753 if (IS_ERR(eventfp)) {
754 r = PTR_ERR(eventfp);
755 break;
756 }
757 if (eventfp != vq->kick) {
758 pollstop = (filep = vq->kick) != NULL;
759 pollstart = (vq->kick = eventfp) != NULL;
760 } else
761 filep = eventfp;
762 break;
763 case VHOST_SET_VRING_CALL:
764 if (copy_from_user(&f, argp, sizeof f)) {
765 r = -EFAULT;
766 break;
767 }
768 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
769 if (IS_ERR(eventfp)) {
770 r = PTR_ERR(eventfp);
771 break;
772 }
773 if (eventfp != vq->call) {
774 filep = vq->call;
775 ctx = vq->call_ctx;
776 vq->call = eventfp;
777 vq->call_ctx = eventfp ?
778 eventfd_ctx_fileget(eventfp) : NULL;
779 } else
780 filep = eventfp;
781 break;
782 case VHOST_SET_VRING_ERR:
783 if (copy_from_user(&f, argp, sizeof f)) {
784 r = -EFAULT;
785 break;
786 }
787 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
788 if (IS_ERR(eventfp)) {
789 r = PTR_ERR(eventfp);
790 break;
791 }
792 if (eventfp != vq->error) {
793 filep = vq->error;
794 vq->error = eventfp;
795 ctx = vq->error_ctx;
796 vq->error_ctx = eventfp ?
797 eventfd_ctx_fileget(eventfp) : NULL;
798 } else
799 filep = eventfp;
800 break;
801 default:
802 r = -ENOIOCTLCMD;
803 }
804
805 if (pollstop && vq->handle_kick)
806 vhost_poll_stop(&vq->poll);
807
808 if (ctx)
809 eventfd_ctx_put(ctx);
810 if (filep)
811 fput(filep);
812
813 if (pollstart && vq->handle_kick)
814 r = vhost_poll_start(&vq->poll, vq->kick);
815
816 mutex_unlock(&vq->mutex);
817
818 if (pollstop && vq->handle_kick)
819 vhost_poll_flush(&vq->poll);
820 return r;
821 }
822 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
823
824 /* Caller must have device mutex */
825 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
826 {
827 struct file *eventfp, *filep = NULL;
828 struct eventfd_ctx *ctx = NULL;
829 u64 p;
830 long r;
831 int i, fd;
832
833 /* If you are not the owner, you can become one */
834 if (ioctl == VHOST_SET_OWNER) {
835 r = vhost_dev_set_owner(d);
836 goto done;
837 }
838
839 /* You must be the owner to do anything else */
840 r = vhost_dev_check_owner(d);
841 if (r)
842 goto done;
843
844 switch (ioctl) {
845 case VHOST_SET_MEM_TABLE:
846 r = vhost_set_memory(d, argp);
847 break;
848 case VHOST_SET_LOG_BASE:
849 if (copy_from_user(&p, argp, sizeof p)) {
850 r = -EFAULT;
851 break;
852 }
853 if ((u64)(unsigned long)p != p) {
854 r = -EFAULT;
855 break;
856 }
857 for (i = 0; i < d->nvqs; ++i) {
858 struct vhost_virtqueue *vq;
859 void __user *base = (void __user *)(unsigned long)p;
860 vq = d->vqs[i];
861 mutex_lock(&vq->mutex);
862 /* If ring is inactive, will check when it's enabled. */
863 if (vq->private_data && !vq_log_access_ok(d, vq, base))
864 r = -EFAULT;
865 else
866 vq->log_base = base;
867 mutex_unlock(&vq->mutex);
868 }
869 break;
870 case VHOST_SET_LOG_FD:
871 r = get_user(fd, (int __user *)argp);
872 if (r < 0)
873 break;
874 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
875 if (IS_ERR(eventfp)) {
876 r = PTR_ERR(eventfp);
877 break;
878 }
879 if (eventfp != d->log_file) {
880 filep = d->log_file;
881 ctx = d->log_ctx;
882 d->log_ctx = eventfp ?
883 eventfd_ctx_fileget(eventfp) : NULL;
884 } else
885 filep = eventfp;
886 for (i = 0; i < d->nvqs; ++i) {
887 mutex_lock(&d->vqs[i]->mutex);
888 d->vqs[i]->log_ctx = d->log_ctx;
889 mutex_unlock(&d->vqs[i]->mutex);
890 }
891 if (ctx)
892 eventfd_ctx_put(ctx);
893 if (filep)
894 fput(filep);
895 break;
896 default:
897 r = -ENOIOCTLCMD;
898 break;
899 }
900 done:
901 return r;
902 }
903 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
904
905 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
906 __u64 addr, __u32 len)
907 {
908 struct vhost_memory_region *reg;
909 int i;
910
911 /* linear search is not brilliant, but we really have on the order of 6
912 * regions in practice */
913 for (i = 0; i < mem->nregions; ++i) {
914 reg = mem->regions + i;
915 if (reg->guest_phys_addr <= addr &&
916 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
917 return reg;
918 }
919 return NULL;
920 }
921
922 /* TODO: This is really inefficient. We need something like get_user()
923 * (instruction directly accesses the data, with an exception table entry
924 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
925 */
926 static int set_bit_to_user(int nr, void __user *addr)
927 {
928 unsigned long log = (unsigned long)addr;
929 struct page *page;
930 void *base;
931 int bit = nr + (log % PAGE_SIZE) * 8;
932 int r;
933
934 r = get_user_pages_fast(log, 1, 1, &page);
935 if (r < 0)
936 return r;
937 BUG_ON(r != 1);
938 base = kmap_atomic(page);
939 set_bit(bit, base);
940 kunmap_atomic(base);
941 set_page_dirty_lock(page);
942 put_page(page);
943 return 0;
944 }
945
946 static int log_write(void __user *log_base,
947 u64 write_address, u64 write_length)
948 {
949 u64 write_page = write_address / VHOST_PAGE_SIZE;
950 int r;
951
952 if (!write_length)
953 return 0;
954 write_length += write_address % VHOST_PAGE_SIZE;
955 for (;;) {
956 u64 base = (u64)(unsigned long)log_base;
957 u64 log = base + write_page / 8;
958 int bit = write_page % 8;
959 if ((u64)(unsigned long)log != log)
960 return -EFAULT;
961 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
962 if (r < 0)
963 return r;
964 if (write_length <= VHOST_PAGE_SIZE)
965 break;
966 write_length -= VHOST_PAGE_SIZE;
967 write_page += 1;
968 }
969 return r;
970 }
971
972 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
973 unsigned int log_num, u64 len)
974 {
975 int i, r;
976
977 /* Make sure data written is seen before log. */
978 smp_wmb();
979 for (i = 0; i < log_num; ++i) {
980 u64 l = min(log[i].len, len);
981 r = log_write(vq->log_base, log[i].addr, l);
982 if (r < 0)
983 return r;
984 len -= l;
985 if (!len) {
986 if (vq->log_ctx)
987 eventfd_signal(vq->log_ctx, 1);
988 return 0;
989 }
990 }
991 /* Length written exceeds what we have stored. This is a bug. */
992 BUG();
993 return 0;
994 }
995 EXPORT_SYMBOL_GPL(vhost_log_write);
996
997 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
998 {
999 void __user *used;
1000 if (__put_user(vq->used_flags, &vq->used->flags) < 0)
1001 return -EFAULT;
1002 if (unlikely(vq->log_used)) {
1003 /* Make sure the flag is seen before log. */
1004 smp_wmb();
1005 /* Log used flag write. */
1006 used = &vq->used->flags;
1007 log_write(vq->log_base, vq->log_addr +
1008 (used - (void __user *)vq->used),
1009 sizeof vq->used->flags);
1010 if (vq->log_ctx)
1011 eventfd_signal(vq->log_ctx, 1);
1012 }
1013 return 0;
1014 }
1015
1016 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1017 {
1018 if (__put_user(vq->avail_idx, vhost_avail_event(vq)))
1019 return -EFAULT;
1020 if (unlikely(vq->log_used)) {
1021 void __user *used;
1022 /* Make sure the event is seen before log. */
1023 smp_wmb();
1024 /* Log avail event write */
1025 used = vhost_avail_event(vq);
1026 log_write(vq->log_base, vq->log_addr +
1027 (used - (void __user *)vq->used),
1028 sizeof *vhost_avail_event(vq));
1029 if (vq->log_ctx)
1030 eventfd_signal(vq->log_ctx, 1);
1031 }
1032 return 0;
1033 }
1034
1035 int vhost_init_used(struct vhost_virtqueue *vq)
1036 {
1037 int r;
1038 if (!vq->private_data)
1039 return 0;
1040
1041 r = vhost_update_used_flags(vq);
1042 if (r)
1043 return r;
1044 vq->signalled_used_valid = false;
1045 return get_user(vq->last_used_idx, &vq->used->idx);
1046 }
1047 EXPORT_SYMBOL_GPL(vhost_init_used);
1048
1049 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
1050 struct iovec iov[], int iov_size)
1051 {
1052 const struct vhost_memory_region *reg;
1053 struct vhost_memory *mem;
1054 struct iovec *_iov;
1055 u64 s = 0;
1056 int ret = 0;
1057
1058 rcu_read_lock();
1059
1060 mem = rcu_dereference(dev->memory);
1061 while ((u64)len > s) {
1062 u64 size;
1063 if (unlikely(ret >= iov_size)) {
1064 ret = -ENOBUFS;
1065 break;
1066 }
1067 reg = find_region(mem, addr, len);
1068 if (unlikely(!reg)) {
1069 ret = -EFAULT;
1070 break;
1071 }
1072 _iov = iov + ret;
1073 size = reg->memory_size - addr + reg->guest_phys_addr;
1074 _iov->iov_len = min((u64)len - s, size);
1075 _iov->iov_base = (void __user *)(unsigned long)
1076 (reg->userspace_addr + addr - reg->guest_phys_addr);
1077 s += size;
1078 addr += size;
1079 ++ret;
1080 }
1081
1082 rcu_read_unlock();
1083 return ret;
1084 }
1085
1086 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1087 * function returns the next descriptor in the chain,
1088 * or -1U if we're at the end. */
1089 static unsigned next_desc(struct vring_desc *desc)
1090 {
1091 unsigned int next;
1092
1093 /* If this descriptor says it doesn't chain, we're done. */
1094 if (!(desc->flags & VRING_DESC_F_NEXT))
1095 return -1U;
1096
1097 /* Check they're not leading us off end of descriptors. */
1098 next = desc->next;
1099 /* Make sure compiler knows to grab that: we don't want it changing! */
1100 /* We will use the result as an index in an array, so most
1101 * architectures only need a compiler barrier here. */
1102 read_barrier_depends();
1103
1104 return next;
1105 }
1106
1107 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1108 struct iovec iov[], unsigned int iov_size,
1109 unsigned int *out_num, unsigned int *in_num,
1110 struct vhost_log *log, unsigned int *log_num,
1111 struct vring_desc *indirect)
1112 {
1113 struct vring_desc desc;
1114 unsigned int i = 0, count, found = 0;
1115 int ret;
1116
1117 /* Sanity check */
1118 if (unlikely(indirect->len % sizeof desc)) {
1119 vq_err(vq, "Invalid length in indirect descriptor: "
1120 "len 0x%llx not multiple of 0x%zx\n",
1121 (unsigned long long)indirect->len,
1122 sizeof desc);
1123 return -EINVAL;
1124 }
1125
1126 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect,
1127 UIO_MAXIOV);
1128 if (unlikely(ret < 0)) {
1129 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1130 return ret;
1131 }
1132
1133 /* We will use the result as an address to read from, so most
1134 * architectures only need a compiler barrier here. */
1135 read_barrier_depends();
1136
1137 count = indirect->len / sizeof desc;
1138 /* Buffers are chained via a 16 bit next field, so
1139 * we can have at most 2^16 of these. */
1140 if (unlikely(count > USHRT_MAX + 1)) {
1141 vq_err(vq, "Indirect buffer length too big: %d\n",
1142 indirect->len);
1143 return -E2BIG;
1144 }
1145
1146 do {
1147 unsigned iov_count = *in_num + *out_num;
1148 if (unlikely(++found > count)) {
1149 vq_err(vq, "Loop detected: last one at %u "
1150 "indirect size %u\n",
1151 i, count);
1152 return -EINVAL;
1153 }
1154 if (unlikely(memcpy_fromiovec((unsigned char *)&desc,
1155 vq->indirect, sizeof desc))) {
1156 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1157 i, (size_t)indirect->addr + i * sizeof desc);
1158 return -EINVAL;
1159 }
1160 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
1161 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1162 i, (size_t)indirect->addr + i * sizeof desc);
1163 return -EINVAL;
1164 }
1165
1166 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1167 iov_size - iov_count);
1168 if (unlikely(ret < 0)) {
1169 vq_err(vq, "Translation failure %d indirect idx %d\n",
1170 ret, i);
1171 return ret;
1172 }
1173 /* If this is an input descriptor, increment that count. */
1174 if (desc.flags & VRING_DESC_F_WRITE) {
1175 *in_num += ret;
1176 if (unlikely(log)) {
1177 log[*log_num].addr = desc.addr;
1178 log[*log_num].len = desc.len;
1179 ++*log_num;
1180 }
1181 } else {
1182 /* If it's an output descriptor, they're all supposed
1183 * to come before any input descriptors. */
1184 if (unlikely(*in_num)) {
1185 vq_err(vq, "Indirect descriptor "
1186 "has out after in: idx %d\n", i);
1187 return -EINVAL;
1188 }
1189 *out_num += ret;
1190 }
1191 } while ((i = next_desc(&desc)) != -1);
1192 return 0;
1193 }
1194
1195 /* This looks in the virtqueue and for the first available buffer, and converts
1196 * it to an iovec for convenient access. Since descriptors consist of some
1197 * number of output then some number of input descriptors, it's actually two
1198 * iovecs, but we pack them into one and note how many of each there were.
1199 *
1200 * This function returns the descriptor number found, or vq->num (which is
1201 * never a valid descriptor number) if none was found. A negative code is
1202 * returned on error. */
1203 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1204 struct iovec iov[], unsigned int iov_size,
1205 unsigned int *out_num, unsigned int *in_num,
1206 struct vhost_log *log, unsigned int *log_num)
1207 {
1208 struct vring_desc desc;
1209 unsigned int i, head, found = 0;
1210 u16 last_avail_idx;
1211 int ret;
1212
1213 /* Check it isn't doing very strange things with descriptor numbers. */
1214 last_avail_idx = vq->last_avail_idx;
1215 if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) {
1216 vq_err(vq, "Failed to access avail idx at %p\n",
1217 &vq->avail->idx);
1218 return -EFAULT;
1219 }
1220
1221 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1222 vq_err(vq, "Guest moved used index from %u to %u",
1223 last_avail_idx, vq->avail_idx);
1224 return -EFAULT;
1225 }
1226
1227 /* If there's nothing new since last we looked, return invalid. */
1228 if (vq->avail_idx == last_avail_idx)
1229 return vq->num;
1230
1231 /* Only get avail ring entries after they have been exposed by guest. */
1232 smp_rmb();
1233
1234 /* Grab the next descriptor number they're advertising, and increment
1235 * the index we've seen. */
1236 if (unlikely(__get_user(head,
1237 &vq->avail->ring[last_avail_idx % vq->num]))) {
1238 vq_err(vq, "Failed to read head: idx %d address %p\n",
1239 last_avail_idx,
1240 &vq->avail->ring[last_avail_idx % vq->num]);
1241 return -EFAULT;
1242 }
1243
1244 /* If their number is silly, that's an error. */
1245 if (unlikely(head >= vq->num)) {
1246 vq_err(vq, "Guest says index %u > %u is available",
1247 head, vq->num);
1248 return -EINVAL;
1249 }
1250
1251 /* When we start there are none of either input nor output. */
1252 *out_num = *in_num = 0;
1253 if (unlikely(log))
1254 *log_num = 0;
1255
1256 i = head;
1257 do {
1258 unsigned iov_count = *in_num + *out_num;
1259 if (unlikely(i >= vq->num)) {
1260 vq_err(vq, "Desc index is %u > %u, head = %u",
1261 i, vq->num, head);
1262 return -EINVAL;
1263 }
1264 if (unlikely(++found > vq->num)) {
1265 vq_err(vq, "Loop detected: last one at %u "
1266 "vq size %u head %u\n",
1267 i, vq->num, head);
1268 return -EINVAL;
1269 }
1270 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1271 if (unlikely(ret)) {
1272 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1273 i, vq->desc + i);
1274 return -EFAULT;
1275 }
1276 if (desc.flags & VRING_DESC_F_INDIRECT) {
1277 ret = get_indirect(dev, vq, iov, iov_size,
1278 out_num, in_num,
1279 log, log_num, &desc);
1280 if (unlikely(ret < 0)) {
1281 vq_err(vq, "Failure detected "
1282 "in indirect descriptor at idx %d\n", i);
1283 return ret;
1284 }
1285 continue;
1286 }
1287
1288 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1289 iov_size - iov_count);
1290 if (unlikely(ret < 0)) {
1291 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1292 ret, i);
1293 return ret;
1294 }
1295 if (desc.flags & VRING_DESC_F_WRITE) {
1296 /* If this is an input descriptor,
1297 * increment that count. */
1298 *in_num += ret;
1299 if (unlikely(log)) {
1300 log[*log_num].addr = desc.addr;
1301 log[*log_num].len = desc.len;
1302 ++*log_num;
1303 }
1304 } else {
1305 /* If it's an output descriptor, they're all supposed
1306 * to come before any input descriptors. */
1307 if (unlikely(*in_num)) {
1308 vq_err(vq, "Descriptor has out after in: "
1309 "idx %d\n", i);
1310 return -EINVAL;
1311 }
1312 *out_num += ret;
1313 }
1314 } while ((i = next_desc(&desc)) != -1);
1315
1316 /* On success, increment avail index. */
1317 vq->last_avail_idx++;
1318
1319 /* Assume notifications from guest are disabled at this point,
1320 * if they aren't we would need to update avail_event index. */
1321 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1322 return head;
1323 }
1324 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
1325
1326 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1327 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1328 {
1329 vq->last_avail_idx -= n;
1330 }
1331 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
1332
1333 /* After we've used one of their buffers, we tell them about it. We'll then
1334 * want to notify the guest, using eventfd. */
1335 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1336 {
1337 struct vring_used_elem heads = { head, len };
1338
1339 return vhost_add_used_n(vq, &heads, 1);
1340 }
1341 EXPORT_SYMBOL_GPL(vhost_add_used);
1342
1343 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1344 struct vring_used_elem *heads,
1345 unsigned count)
1346 {
1347 struct vring_used_elem __user *used;
1348 u16 old, new;
1349 int start;
1350
1351 start = vq->last_used_idx % vq->num;
1352 used = vq->used->ring + start;
1353 if (count == 1) {
1354 if (__put_user(heads[0].id, &used->id)) {
1355 vq_err(vq, "Failed to write used id");
1356 return -EFAULT;
1357 }
1358 if (__put_user(heads[0].len, &used->len)) {
1359 vq_err(vq, "Failed to write used len");
1360 return -EFAULT;
1361 }
1362 } else if (__copy_to_user(used, heads, count * sizeof *used)) {
1363 vq_err(vq, "Failed to write used");
1364 return -EFAULT;
1365 }
1366 if (unlikely(vq->log_used)) {
1367 /* Make sure data is seen before log. */
1368 smp_wmb();
1369 /* Log used ring entry write. */
1370 log_write(vq->log_base,
1371 vq->log_addr +
1372 ((void __user *)used - (void __user *)vq->used),
1373 count * sizeof *used);
1374 }
1375 old = vq->last_used_idx;
1376 new = (vq->last_used_idx += count);
1377 /* If the driver never bothers to signal in a very long while,
1378 * used index might wrap around. If that happens, invalidate
1379 * signalled_used index we stored. TODO: make sure driver
1380 * signals at least once in 2^16 and remove this. */
1381 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1382 vq->signalled_used_valid = false;
1383 return 0;
1384 }
1385
1386 /* After we've used one of their buffers, we tell them about it. We'll then
1387 * want to notify the guest, using eventfd. */
1388 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1389 unsigned count)
1390 {
1391 int start, n, r;
1392
1393 start = vq->last_used_idx % vq->num;
1394 n = vq->num - start;
1395 if (n < count) {
1396 r = __vhost_add_used_n(vq, heads, n);
1397 if (r < 0)
1398 return r;
1399 heads += n;
1400 count -= n;
1401 }
1402 r = __vhost_add_used_n(vq, heads, count);
1403
1404 /* Make sure buffer is written before we update index. */
1405 smp_wmb();
1406 if (put_user(vq->last_used_idx, &vq->used->idx)) {
1407 vq_err(vq, "Failed to increment used idx");
1408 return -EFAULT;
1409 }
1410 if (unlikely(vq->log_used)) {
1411 /* Log used index update. */
1412 log_write(vq->log_base,
1413 vq->log_addr + offsetof(struct vring_used, idx),
1414 sizeof vq->used->idx);
1415 if (vq->log_ctx)
1416 eventfd_signal(vq->log_ctx, 1);
1417 }
1418 return r;
1419 }
1420 EXPORT_SYMBOL_GPL(vhost_add_used_n);
1421
1422 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1423 {
1424 __u16 old, new, event;
1425 bool v;
1426 /* Flush out used index updates. This is paired
1427 * with the barrier that the Guest executes when enabling
1428 * interrupts. */
1429 smp_mb();
1430
1431 if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1432 unlikely(vq->avail_idx == vq->last_avail_idx))
1433 return true;
1434
1435 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1436 __u16 flags;
1437 if (__get_user(flags, &vq->avail->flags)) {
1438 vq_err(vq, "Failed to get flags");
1439 return true;
1440 }
1441 return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
1442 }
1443 old = vq->signalled_used;
1444 v = vq->signalled_used_valid;
1445 new = vq->signalled_used = vq->last_used_idx;
1446 vq->signalled_used_valid = true;
1447
1448 if (unlikely(!v))
1449 return true;
1450
1451 if (get_user(event, vhost_used_event(vq))) {
1452 vq_err(vq, "Failed to get used event idx");
1453 return true;
1454 }
1455 return vring_need_event(event, new, old);
1456 }
1457
1458 /* This actually signals the guest, using eventfd. */
1459 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1460 {
1461 /* Signal the Guest tell them we used something up. */
1462 if (vq->call_ctx && vhost_notify(dev, vq))
1463 eventfd_signal(vq->call_ctx, 1);
1464 }
1465 EXPORT_SYMBOL_GPL(vhost_signal);
1466
1467 /* And here's the combo meal deal. Supersize me! */
1468 void vhost_add_used_and_signal(struct vhost_dev *dev,
1469 struct vhost_virtqueue *vq,
1470 unsigned int head, int len)
1471 {
1472 vhost_add_used(vq, head, len);
1473 vhost_signal(dev, vq);
1474 }
1475 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
1476
1477 /* multi-buffer version of vhost_add_used_and_signal */
1478 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1479 struct vhost_virtqueue *vq,
1480 struct vring_used_elem *heads, unsigned count)
1481 {
1482 vhost_add_used_n(vq, heads, count);
1483 vhost_signal(dev, vq);
1484 }
1485 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
1486
1487 /* OK, now we need to know about added descriptors. */
1488 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1489 {
1490 u16 avail_idx;
1491 int r;
1492
1493 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1494 return false;
1495 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1496 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1497 r = vhost_update_used_flags(vq);
1498 if (r) {
1499 vq_err(vq, "Failed to enable notification at %p: %d\n",
1500 &vq->used->flags, r);
1501 return false;
1502 }
1503 } else {
1504 r = vhost_update_avail_event(vq, vq->avail_idx);
1505 if (r) {
1506 vq_err(vq, "Failed to update avail event index at %p: %d\n",
1507 vhost_avail_event(vq), r);
1508 return false;
1509 }
1510 }
1511 /* They could have slipped one in as we were doing that: make
1512 * sure it's written, then check again. */
1513 smp_mb();
1514 r = __get_user(avail_idx, &vq->avail->idx);
1515 if (r) {
1516 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1517 &vq->avail->idx, r);
1518 return false;
1519 }
1520
1521 return avail_idx != vq->avail_idx;
1522 }
1523 EXPORT_SYMBOL_GPL(vhost_enable_notify);
1524
1525 /* We don't need to be notified again. */
1526 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1527 {
1528 int r;
1529
1530 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1531 return;
1532 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1533 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1534 r = vhost_update_used_flags(vq);
1535 if (r)
1536 vq_err(vq, "Failed to enable notification at %p: %d\n",
1537 &vq->used->flags, r);
1538 }
1539 }
1540 EXPORT_SYMBOL_GPL(vhost_disable_notify);
1541
1542 static int __init vhost_init(void)
1543 {
1544 return 0;
1545 }
1546
1547 static void __exit vhost_exit(void)
1548 {
1549 }
1550
1551 module_init(vhost_init);
1552 module_exit(vhost_exit);
1553
1554 MODULE_VERSION("0.0.1");
1555 MODULE_LICENSE("GPL v2");
1556 MODULE_AUTHOR("Michael S. Tsirkin");
1557 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
Linux with added FPC-III support