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PM / sleep: Asynchronous threads for suspend_noirq
[linux/fpc-iii.git] / drivers / vhost / vhost.c
blob78987e481bc6a3e578f1ea5789802ae9b1ae7045
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 void 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 EXPORT_SYMBOL_GPL(vhost_dev_init);
324
325 /* Caller should have device mutex */
326 long vhost_dev_check_owner(struct vhost_dev *dev)
327 {
328 /* Are you the owner? If not, I don't think you mean to do that */
329 return dev->mm == current->mm ? 0 : -EPERM;
330 }
331 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
332
333 struct vhost_attach_cgroups_struct {
334 struct vhost_work work;
335 struct task_struct *owner;
336 int ret;
337 };
338
339 static void vhost_attach_cgroups_work(struct vhost_work *work)
340 {
341 struct vhost_attach_cgroups_struct *s;
342
343 s = container_of(work, struct vhost_attach_cgroups_struct, work);
344 s->ret = cgroup_attach_task_all(s->owner, current);
345 }
346
347 static int vhost_attach_cgroups(struct vhost_dev *dev)
348 {
349 struct vhost_attach_cgroups_struct attach;
350
351 attach.owner = current;
352 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
353 vhost_work_queue(dev, &attach.work);
354 vhost_work_flush(dev, &attach.work);
355 return attach.ret;
356 }
357
358 /* Caller should have device mutex */
359 bool vhost_dev_has_owner(struct vhost_dev *dev)
360 {
361 return dev->mm;
362 }
363 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
364
365 /* Caller should have device mutex */
366 long vhost_dev_set_owner(struct vhost_dev *dev)
367 {
368 struct task_struct *worker;
369 int err;
370
371 /* Is there an owner already? */
372 if (vhost_dev_has_owner(dev)) {
373 err = -EBUSY;
374 goto err_mm;
375 }
376
377 /* No owner, become one */
378 dev->mm = get_task_mm(current);
379 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
380 if (IS_ERR(worker)) {
381 err = PTR_ERR(worker);
382 goto err_worker;
383 }
384
385 dev->worker = worker;
386 wake_up_process(worker); /* avoid contributing to loadavg */
387
388 err = vhost_attach_cgroups(dev);
389 if (err)
390 goto err_cgroup;
391
392 err = vhost_dev_alloc_iovecs(dev);
393 if (err)
394 goto err_cgroup;
395
396 return 0;
397 err_cgroup:
398 kthread_stop(worker);
399 dev->worker = NULL;
400 err_worker:
401 if (dev->mm)
402 mmput(dev->mm);
403 dev->mm = NULL;
404 err_mm:
405 return err;
406 }
407 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
408
409 struct vhost_memory *vhost_dev_reset_owner_prepare(void)
410 {
411 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
412 }
413 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
414
415 /* Caller should have device mutex */
416 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory)
417 {
418 vhost_dev_cleanup(dev, true);
419
420 /* Restore memory to default empty mapping. */
421 memory->nregions = 0;
422 RCU_INIT_POINTER(dev->memory, memory);
423 }
424 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
425
426 void vhost_dev_stop(struct vhost_dev *dev)
427 {
428 int i;
429
430 for (i = 0; i < dev->nvqs; ++i) {
431 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
432 vhost_poll_stop(&dev->vqs[i]->poll);
433 vhost_poll_flush(&dev->vqs[i]->poll);
434 }
435 }
436 }
437 EXPORT_SYMBOL_GPL(vhost_dev_stop);
438
439 /* Caller should have device mutex if and only if locked is set */
440 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
441 {
442 int i;
443
444 for (i = 0; i < dev->nvqs; ++i) {
445 if (dev->vqs[i]->error_ctx)
446 eventfd_ctx_put(dev->vqs[i]->error_ctx);
447 if (dev->vqs[i]->error)
448 fput(dev->vqs[i]->error);
449 if (dev->vqs[i]->kick)
450 fput(dev->vqs[i]->kick);
451 if (dev->vqs[i]->call_ctx)
452 eventfd_ctx_put(dev->vqs[i]->call_ctx);
453 if (dev->vqs[i]->call)
454 fput(dev->vqs[i]->call);
455 vhost_vq_reset(dev, dev->vqs[i]);
456 }
457 vhost_dev_free_iovecs(dev);
458 if (dev->log_ctx)
459 eventfd_ctx_put(dev->log_ctx);
460 dev->log_ctx = NULL;
461 if (dev->log_file)
462 fput(dev->log_file);
463 dev->log_file = NULL;
464 /* No one will access memory at this point */
465 kfree(rcu_dereference_protected(dev->memory,
466 locked ==
467 lockdep_is_held(&dev->mutex)));
468 RCU_INIT_POINTER(dev->memory, NULL);
469 WARN_ON(!list_empty(&dev->work_list));
470 if (dev->worker) {
471 kthread_stop(dev->worker);
472 dev->worker = NULL;
473 }
474 if (dev->mm)
475 mmput(dev->mm);
476 dev->mm = NULL;
477 }
478 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
479
480 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
481 {
482 u64 a = addr / VHOST_PAGE_SIZE / 8;
483
484 /* Make sure 64 bit math will not overflow. */
485 if (a > ULONG_MAX - (unsigned long)log_base ||
486 a + (unsigned long)log_base > ULONG_MAX)
487 return 0;
488
489 return access_ok(VERIFY_WRITE, log_base + a,
490 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
491 }
492
493 /* Caller should have vq mutex and device mutex. */
494 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
495 int log_all)
496 {
497 int i;
498
499 if (!mem)
500 return 0;
501
502 for (i = 0; i < mem->nregions; ++i) {
503 struct vhost_memory_region *m = mem->regions + i;
504 unsigned long a = m->userspace_addr;
505 if (m->memory_size > ULONG_MAX)
506 return 0;
507 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
508 m->memory_size))
509 return 0;
510 else if (log_all && !log_access_ok(log_base,
511 m->guest_phys_addr,
512 m->memory_size))
513 return 0;
514 }
515 return 1;
516 }
517
518 /* Can we switch to this memory table? */
519 /* Caller should have device mutex but not vq mutex */
520 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
521 int log_all)
522 {
523 int i;
524
525 for (i = 0; i < d->nvqs; ++i) {
526 int ok;
527 mutex_lock(&d->vqs[i]->mutex);
528 /* If ring is inactive, will check when it's enabled. */
529 if (d->vqs[i]->private_data)
530 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem,
531 log_all);
532 else
533 ok = 1;
534 mutex_unlock(&d->vqs[i]->mutex);
535 if (!ok)
536 return 0;
537 }
538 return 1;
539 }
540
541 static int vq_access_ok(struct vhost_dev *d, unsigned int num,
542 struct vring_desc __user *desc,
543 struct vring_avail __user *avail,
544 struct vring_used __user *used)
545 {
546 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
547 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
548 access_ok(VERIFY_READ, avail,
549 sizeof *avail + num * sizeof *avail->ring + s) &&
550 access_ok(VERIFY_WRITE, used,
551 sizeof *used + num * sizeof *used->ring + s);
552 }
553
554 /* Can we log writes? */
555 /* Caller should have device mutex but not vq mutex */
556 int vhost_log_access_ok(struct vhost_dev *dev)
557 {
558 struct vhost_memory *mp;
559
560 mp = rcu_dereference_protected(dev->memory,
561 lockdep_is_held(&dev->mutex));
562 return memory_access_ok(dev, mp, 1);
563 }
564 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
565
566 /* Verify access for write logging. */
567 /* Caller should have vq mutex and device mutex */
568 static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
569 void __user *log_base)
570 {
571 struct vhost_memory *mp;
572 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
573
574 mp = rcu_dereference_protected(vq->dev->memory,
575 lockdep_is_held(&vq->mutex));
576 return vq_memory_access_ok(log_base, mp,
577 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
578 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
579 sizeof *vq->used +
580 vq->num * sizeof *vq->used->ring + s));
581 }
582
583 /* Can we start vq? */
584 /* Caller should have vq mutex and device mutex */
585 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
586 {
587 return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
588 vq_log_access_ok(vq->dev, vq, vq->log_base);
589 }
590 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
591
592 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
593 {
594 struct vhost_memory mem, *newmem, *oldmem;
595 unsigned long size = offsetof(struct vhost_memory, regions);
596
597 if (copy_from_user(&mem, m, size))
598 return -EFAULT;
599 if (mem.padding)
600 return -EOPNOTSUPP;
601 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
602 return -E2BIG;
603 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL);
604 if (!newmem)
605 return -ENOMEM;
606
607 memcpy(newmem, &mem, size);
608 if (copy_from_user(newmem->regions, m->regions,
609 mem.nregions * sizeof *m->regions)) {
610 kfree(newmem);
611 return -EFAULT;
612 }
613
614 if (!memory_access_ok(d, newmem,
615 vhost_has_feature(d, VHOST_F_LOG_ALL))) {
616 kfree(newmem);
617 return -EFAULT;
618 }
619 oldmem = rcu_dereference_protected(d->memory,
620 lockdep_is_held(&d->mutex));
621 rcu_assign_pointer(d->memory, newmem);
622 synchronize_rcu();
623 kfree(oldmem);
624 return 0;
625 }
626
627 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
628 {
629 struct file *eventfp, *filep = NULL;
630 bool pollstart = false, pollstop = false;
631 struct eventfd_ctx *ctx = NULL;
632 u32 __user *idxp = argp;
633 struct vhost_virtqueue *vq;
634 struct vhost_vring_state s;
635 struct vhost_vring_file f;
636 struct vhost_vring_addr a;
637 u32 idx;
638 long r;
639
640 r = get_user(idx, idxp);
641 if (r < 0)
642 return r;
643 if (idx >= d->nvqs)
644 return -ENOBUFS;
645
646 vq = d->vqs[idx];
647
648 mutex_lock(&vq->mutex);
649
650 switch (ioctl) {
651 case VHOST_SET_VRING_NUM:
652 /* Resizing ring with an active backend?
653 * You don't want to do that. */
654 if (vq->private_data) {
655 r = -EBUSY;
656 break;
657 }
658 if (copy_from_user(&s, argp, sizeof s)) {
659 r = -EFAULT;
660 break;
661 }
662 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
663 r = -EINVAL;
664 break;
665 }
666 vq->num = s.num;
667 break;
668 case VHOST_SET_VRING_BASE:
669 /* Moving base with an active backend?
670 * You don't want to do that. */
671 if (vq->private_data) {
672 r = -EBUSY;
673 break;
674 }
675 if (copy_from_user(&s, argp, sizeof s)) {
676 r = -EFAULT;
677 break;
678 }
679 if (s.num > 0xffff) {
680 r = -EINVAL;
681 break;
682 }
683 vq->last_avail_idx = s.num;
684 /* Forget the cached index value. */
685 vq->avail_idx = vq->last_avail_idx;
686 break;
687 case VHOST_GET_VRING_BASE:
688 s.index = idx;
689 s.num = vq->last_avail_idx;
690 if (copy_to_user(argp, &s, sizeof s))
691 r = -EFAULT;
692 break;
693 case VHOST_SET_VRING_ADDR:
694 if (copy_from_user(&a, argp, sizeof a)) {
695 r = -EFAULT;
696 break;
697 }
698 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
699 r = -EOPNOTSUPP;
700 break;
701 }
702 /* For 32bit, verify that the top 32bits of the user
703 data are set to zero. */
704 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
705 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
706 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
707 r = -EFAULT;
708 break;
709 }
710 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
711 (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
712 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
713 r = -EINVAL;
714 break;
715 }
716
717 /* We only verify access here if backend is configured.
718 * If it is not, we don't as size might not have been setup.
719 * We will verify when backend is configured. */
720 if (vq->private_data) {
721 if (!vq_access_ok(d, vq->num,
722 (void __user *)(unsigned long)a.desc_user_addr,
723 (void __user *)(unsigned long)a.avail_user_addr,
724 (void __user *)(unsigned long)a.used_user_addr)) {
725 r = -EINVAL;
726 break;
727 }
728
729 /* Also validate log access for used ring if enabled. */
730 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
731 !log_access_ok(vq->log_base, a.log_guest_addr,
732 sizeof *vq->used +
733 vq->num * sizeof *vq->used->ring)) {
734 r = -EINVAL;
735 break;
736 }
737 }
738
739 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
740 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
741 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
742 vq->log_addr = a.log_guest_addr;
743 vq->used = (void __user *)(unsigned long)a.used_user_addr;
744 break;
745 case VHOST_SET_VRING_KICK:
746 if (copy_from_user(&f, argp, sizeof f)) {
747 r = -EFAULT;
748 break;
749 }
750 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
751 if (IS_ERR(eventfp)) {
752 r = PTR_ERR(eventfp);
753 break;
754 }
755 if (eventfp != vq->kick) {
756 pollstop = (filep = vq->kick) != NULL;
757 pollstart = (vq->kick = eventfp) != NULL;
758 } else
759 filep = eventfp;
760 break;
761 case VHOST_SET_VRING_CALL:
762 if (copy_from_user(&f, argp, sizeof f)) {
763 r = -EFAULT;
764 break;
765 }
766 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
767 if (IS_ERR(eventfp)) {
768 r = PTR_ERR(eventfp);
769 break;
770 }
771 if (eventfp != vq->call) {
772 filep = vq->call;
773 ctx = vq->call_ctx;
774 vq->call = eventfp;
775 vq->call_ctx = eventfp ?
776 eventfd_ctx_fileget(eventfp) : NULL;
777 } else
778 filep = eventfp;
779 break;
780 case VHOST_SET_VRING_ERR:
781 if (copy_from_user(&f, argp, sizeof f)) {
782 r = -EFAULT;
783 break;
784 }
785 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
786 if (IS_ERR(eventfp)) {
787 r = PTR_ERR(eventfp);
788 break;
789 }
790 if (eventfp != vq->error) {
791 filep = vq->error;
792 vq->error = eventfp;
793 ctx = vq->error_ctx;
794 vq->error_ctx = eventfp ?
795 eventfd_ctx_fileget(eventfp) : NULL;
796 } else
797 filep = eventfp;
798 break;
799 default:
800 r = -ENOIOCTLCMD;
801 }
802
803 if (pollstop && vq->handle_kick)
804 vhost_poll_stop(&vq->poll);
805
806 if (ctx)
807 eventfd_ctx_put(ctx);
808 if (filep)
809 fput(filep);
810
811 if (pollstart && vq->handle_kick)
812 r = vhost_poll_start(&vq->poll, vq->kick);
813
814 mutex_unlock(&vq->mutex);
815
816 if (pollstop && vq->handle_kick)
817 vhost_poll_flush(&vq->poll);
818 return r;
819 }
820 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
821
822 /* Caller must have device mutex */
823 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
824 {
825 struct file *eventfp, *filep = NULL;
826 struct eventfd_ctx *ctx = NULL;
827 u64 p;
828 long r;
829 int i, fd;
830
831 /* If you are not the owner, you can become one */
832 if (ioctl == VHOST_SET_OWNER) {
833 r = vhost_dev_set_owner(d);
834 goto done;
835 }
836
837 /* You must be the owner to do anything else */
838 r = vhost_dev_check_owner(d);
839 if (r)
840 goto done;
841
842 switch (ioctl) {
843 case VHOST_SET_MEM_TABLE:
844 r = vhost_set_memory(d, argp);
845 break;
846 case VHOST_SET_LOG_BASE:
847 if (copy_from_user(&p, argp, sizeof p)) {
848 r = -EFAULT;
849 break;
850 }
851 if ((u64)(unsigned long)p != p) {
852 r = -EFAULT;
853 break;
854 }
855 for (i = 0; i < d->nvqs; ++i) {
856 struct vhost_virtqueue *vq;
857 void __user *base = (void __user *)(unsigned long)p;
858 vq = d->vqs[i];
859 mutex_lock(&vq->mutex);
860 /* If ring is inactive, will check when it's enabled. */
861 if (vq->private_data && !vq_log_access_ok(d, vq, base))
862 r = -EFAULT;
863 else
864 vq->log_base = base;
865 mutex_unlock(&vq->mutex);
866 }
867 break;
868 case VHOST_SET_LOG_FD:
869 r = get_user(fd, (int __user *)argp);
870 if (r < 0)
871 break;
872 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
873 if (IS_ERR(eventfp)) {
874 r = PTR_ERR(eventfp);
875 break;
876 }
877 if (eventfp != d->log_file) {
878 filep = d->log_file;
879 ctx = d->log_ctx;
880 d->log_ctx = eventfp ?
881 eventfd_ctx_fileget(eventfp) : NULL;
882 } else
883 filep = eventfp;
884 for (i = 0; i < d->nvqs; ++i) {
885 mutex_lock(&d->vqs[i]->mutex);
886 d->vqs[i]->log_ctx = d->log_ctx;
887 mutex_unlock(&d->vqs[i]->mutex);
888 }
889 if (ctx)
890 eventfd_ctx_put(ctx);
891 if (filep)
892 fput(filep);
893 break;
894 default:
895 r = -ENOIOCTLCMD;
896 break;
897 }
898 done:
899 return r;
900 }
901 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
902
903 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
904 __u64 addr, __u32 len)
905 {
906 struct vhost_memory_region *reg;
907 int i;
908
909 /* linear search is not brilliant, but we really have on the order of 6
910 * regions in practice */
911 for (i = 0; i < mem->nregions; ++i) {
912 reg = mem->regions + i;
913 if (reg->guest_phys_addr <= addr &&
914 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
915 return reg;
916 }
917 return NULL;
918 }
919
920 /* TODO: This is really inefficient. We need something like get_user()
921 * (instruction directly accesses the data, with an exception table entry
922 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
923 */
924 static int set_bit_to_user(int nr, void __user *addr)
925 {
926 unsigned long log = (unsigned long)addr;
927 struct page *page;
928 void *base;
929 int bit = nr + (log % PAGE_SIZE) * 8;
930 int r;
931
932 r = get_user_pages_fast(log, 1, 1, &page);
933 if (r < 0)
934 return r;
935 BUG_ON(r != 1);
936 base = kmap_atomic(page);
937 set_bit(bit, base);
938 kunmap_atomic(base);
939 set_page_dirty_lock(page);
940 put_page(page);
941 return 0;
942 }
943
944 static int log_write(void __user *log_base,
945 u64 write_address, u64 write_length)
946 {
947 u64 write_page = write_address / VHOST_PAGE_SIZE;
948 int r;
949
950 if (!write_length)
951 return 0;
952 write_length += write_address % VHOST_PAGE_SIZE;
953 for (;;) {
954 u64 base = (u64)(unsigned long)log_base;
955 u64 log = base + write_page / 8;
956 int bit = write_page % 8;
957 if ((u64)(unsigned long)log != log)
958 return -EFAULT;
959 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
960 if (r < 0)
961 return r;
962 if (write_length <= VHOST_PAGE_SIZE)
963 break;
964 write_length -= VHOST_PAGE_SIZE;
965 write_page += 1;
966 }
967 return r;
968 }
969
970 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
971 unsigned int log_num, u64 len)
972 {
973 int i, r;
974
975 /* Make sure data written is seen before log. */
976 smp_wmb();
977 for (i = 0; i < log_num; ++i) {
978 u64 l = min(log[i].len, len);
979 r = log_write(vq->log_base, log[i].addr, l);
980 if (r < 0)
981 return r;
982 len -= l;
983 if (!len) {
984 if (vq->log_ctx)
985 eventfd_signal(vq->log_ctx, 1);
986 return 0;
987 }
988 }
989 /* Length written exceeds what we have stored. This is a bug. */
990 BUG();
991 return 0;
992 }
993 EXPORT_SYMBOL_GPL(vhost_log_write);
994
995 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
996 {
997 void __user *used;
998 if (__put_user(vq->used_flags, &vq->used->flags) < 0)
999 return -EFAULT;
1000 if (unlikely(vq->log_used)) {
1001 /* Make sure the flag is seen before log. */
1002 smp_wmb();
1003 /* Log used flag write. */
1004 used = &vq->used->flags;
1005 log_write(vq->log_base, vq->log_addr +
1006 (used - (void __user *)vq->used),
1007 sizeof vq->used->flags);
1008 if (vq->log_ctx)
1009 eventfd_signal(vq->log_ctx, 1);
1010 }
1011 return 0;
1012 }
1013
1014 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1015 {
1016 if (__put_user(vq->avail_idx, vhost_avail_event(vq)))
1017 return -EFAULT;
1018 if (unlikely(vq->log_used)) {
1019 void __user *used;
1020 /* Make sure the event is seen before log. */
1021 smp_wmb();
1022 /* Log avail event write */
1023 used = vhost_avail_event(vq);
1024 log_write(vq->log_base, vq->log_addr +
1025 (used - (void __user *)vq->used),
1026 sizeof *vhost_avail_event(vq));
1027 if (vq->log_ctx)
1028 eventfd_signal(vq->log_ctx, 1);
1029 }
1030 return 0;
1031 }
1032
1033 int vhost_init_used(struct vhost_virtqueue *vq)
1034 {
1035 int r;
1036 if (!vq->private_data)
1037 return 0;
1038
1039 r = vhost_update_used_flags(vq);
1040 if (r)
1041 return r;
1042 vq->signalled_used_valid = false;
1043 return get_user(vq->last_used_idx, &vq->used->idx);
1044 }
1045 EXPORT_SYMBOL_GPL(vhost_init_used);
1046
1047 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
1048 struct iovec iov[], int iov_size)
1049 {
1050 const struct vhost_memory_region *reg;
1051 struct vhost_memory *mem;
1052 struct iovec *_iov;
1053 u64 s = 0;
1054 int ret = 0;
1055
1056 rcu_read_lock();
1057
1058 mem = rcu_dereference(dev->memory);
1059 while ((u64)len > s) {
1060 u64 size;
1061 if (unlikely(ret >= iov_size)) {
1062 ret = -ENOBUFS;
1063 break;
1064 }
1065 reg = find_region(mem, addr, len);
1066 if (unlikely(!reg)) {
1067 ret = -EFAULT;
1068 break;
1069 }
1070 _iov = iov + ret;
1071 size = reg->memory_size - addr + reg->guest_phys_addr;
1072 _iov->iov_len = min((u64)len - s, size);
1073 _iov->iov_base = (void __user *)(unsigned long)
1074 (reg->userspace_addr + addr - reg->guest_phys_addr);
1075 s += size;
1076 addr += size;
1077 ++ret;
1078 }
1079
1080 rcu_read_unlock();
1081 return ret;
1082 }
1083
1084 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1085 * function returns the next descriptor in the chain,
1086 * or -1U if we're at the end. */
1087 static unsigned next_desc(struct vring_desc *desc)
1088 {
1089 unsigned int next;
1090
1091 /* If this descriptor says it doesn't chain, we're done. */
1092 if (!(desc->flags & VRING_DESC_F_NEXT))
1093 return -1U;
1094
1095 /* Check they're not leading us off end of descriptors. */
1096 next = desc->next;
1097 /* Make sure compiler knows to grab that: we don't want it changing! */
1098 /* We will use the result as an index in an array, so most
1099 * architectures only need a compiler barrier here. */
1100 read_barrier_depends();
1101
1102 return next;
1103 }
1104
1105 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1106 struct iovec iov[], unsigned int iov_size,
1107 unsigned int *out_num, unsigned int *in_num,
1108 struct vhost_log *log, unsigned int *log_num,
1109 struct vring_desc *indirect)
1110 {
1111 struct vring_desc desc;
1112 unsigned int i = 0, count, found = 0;
1113 int ret;
1114
1115 /* Sanity check */
1116 if (unlikely(indirect->len % sizeof desc)) {
1117 vq_err(vq, "Invalid length in indirect descriptor: "
1118 "len 0x%llx not multiple of 0x%zx\n",
1119 (unsigned long long)indirect->len,
1120 sizeof desc);
1121 return -EINVAL;
1122 }
1123
1124 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect,
1125 UIO_MAXIOV);
1126 if (unlikely(ret < 0)) {
1127 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1128 return ret;
1129 }
1130
1131 /* We will use the result as an address to read from, so most
1132 * architectures only need a compiler barrier here. */
1133 read_barrier_depends();
1134
1135 count = indirect->len / sizeof desc;
1136 /* Buffers are chained via a 16 bit next field, so
1137 * we can have at most 2^16 of these. */
1138 if (unlikely(count > USHRT_MAX + 1)) {
1139 vq_err(vq, "Indirect buffer length too big: %d\n",
1140 indirect->len);
1141 return -E2BIG;
1142 }
1143
1144 do {
1145 unsigned iov_count = *in_num + *out_num;
1146 if (unlikely(++found > count)) {
1147 vq_err(vq, "Loop detected: last one at %u "
1148 "indirect size %u\n",
1149 i, count);
1150 return -EINVAL;
1151 }
1152 if (unlikely(memcpy_fromiovec((unsigned char *)&desc,
1153 vq->indirect, sizeof desc))) {
1154 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1155 i, (size_t)indirect->addr + i * sizeof desc);
1156 return -EINVAL;
1157 }
1158 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
1159 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1160 i, (size_t)indirect->addr + i * sizeof desc);
1161 return -EINVAL;
1162 }
1163
1164 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1165 iov_size - iov_count);
1166 if (unlikely(ret < 0)) {
1167 vq_err(vq, "Translation failure %d indirect idx %d\n",
1168 ret, i);
1169 return ret;
1170 }
1171 /* If this is an input descriptor, increment that count. */
1172 if (desc.flags & VRING_DESC_F_WRITE) {
1173 *in_num += ret;
1174 if (unlikely(log)) {
1175 log[*log_num].addr = desc.addr;
1176 log[*log_num].len = desc.len;
1177 ++*log_num;
1178 }
1179 } else {
1180 /* If it's an output descriptor, they're all supposed
1181 * to come before any input descriptors. */
1182 if (unlikely(*in_num)) {
1183 vq_err(vq, "Indirect descriptor "
1184 "has out after in: idx %d\n", i);
1185 return -EINVAL;
1186 }
1187 *out_num += ret;
1188 }
1189 } while ((i = next_desc(&desc)) != -1);
1190 return 0;
1191 }
1192
1193 /* This looks in the virtqueue and for the first available buffer, and converts
1194 * it to an iovec for convenient access. Since descriptors consist of some
1195 * number of output then some number of input descriptors, it's actually two
1196 * iovecs, but we pack them into one and note how many of each there were.
1197 *
1198 * This function returns the descriptor number found, or vq->num (which is
1199 * never a valid descriptor number) if none was found. A negative code is
1200 * returned on error. */
1201 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1202 struct iovec iov[], unsigned int iov_size,
1203 unsigned int *out_num, unsigned int *in_num,
1204 struct vhost_log *log, unsigned int *log_num)
1205 {
1206 struct vring_desc desc;
1207 unsigned int i, head, found = 0;
1208 u16 last_avail_idx;
1209 int ret;
1210
1211 /* Check it isn't doing very strange things with descriptor numbers. */
1212 last_avail_idx = vq->last_avail_idx;
1213 if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) {
1214 vq_err(vq, "Failed to access avail idx at %p\n",
1215 &vq->avail->idx);
1216 return -EFAULT;
1217 }
1218
1219 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1220 vq_err(vq, "Guest moved used index from %u to %u",
1221 last_avail_idx, vq->avail_idx);
1222 return -EFAULT;
1223 }
1224
1225 /* If there's nothing new since last we looked, return invalid. */
1226 if (vq->avail_idx == last_avail_idx)
1227 return vq->num;
1228
1229 /* Only get avail ring entries after they have been exposed by guest. */
1230 smp_rmb();
1231
1232 /* Grab the next descriptor number they're advertising, and increment
1233 * the index we've seen. */
1234 if (unlikely(__get_user(head,
1235 &vq->avail->ring[last_avail_idx % vq->num]))) {
1236 vq_err(vq, "Failed to read head: idx %d address %p\n",
1237 last_avail_idx,
1238 &vq->avail->ring[last_avail_idx % vq->num]);
1239 return -EFAULT;
1240 }
1241
1242 /* If their number is silly, that's an error. */
1243 if (unlikely(head >= vq->num)) {
1244 vq_err(vq, "Guest says index %u > %u is available",
1245 head, vq->num);
1246 return -EINVAL;
1247 }
1248
1249 /* When we start there are none of either input nor output. */
1250 *out_num = *in_num = 0;
1251 if (unlikely(log))
1252 *log_num = 0;
1253
1254 i = head;
1255 do {
1256 unsigned iov_count = *in_num + *out_num;
1257 if (unlikely(i >= vq->num)) {
1258 vq_err(vq, "Desc index is %u > %u, head = %u",
1259 i, vq->num, head);
1260 return -EINVAL;
1261 }
1262 if (unlikely(++found > vq->num)) {
1263 vq_err(vq, "Loop detected: last one at %u "
1264 "vq size %u head %u\n",
1265 i, vq->num, head);
1266 return -EINVAL;
1267 }
1268 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1269 if (unlikely(ret)) {
1270 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1271 i, vq->desc + i);
1272 return -EFAULT;
1273 }
1274 if (desc.flags & VRING_DESC_F_INDIRECT) {
1275 ret = get_indirect(dev, vq, iov, iov_size,
1276 out_num, in_num,
1277 log, log_num, &desc);
1278 if (unlikely(ret < 0)) {
1279 vq_err(vq, "Failure detected "
1280 "in indirect descriptor at idx %d\n", i);
1281 return ret;
1282 }
1283 continue;
1284 }
1285
1286 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1287 iov_size - iov_count);
1288 if (unlikely(ret < 0)) {
1289 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1290 ret, i);
1291 return ret;
1292 }
1293 if (desc.flags & VRING_DESC_F_WRITE) {
1294 /* If this is an input descriptor,
1295 * increment that count. */
1296 *in_num += ret;
1297 if (unlikely(log)) {
1298 log[*log_num].addr = desc.addr;
1299 log[*log_num].len = desc.len;
1300 ++*log_num;
1301 }
1302 } else {
1303 /* If it's an output descriptor, they're all supposed
1304 * to come before any input descriptors. */
1305 if (unlikely(*in_num)) {
1306 vq_err(vq, "Descriptor has out after in: "
1307 "idx %d\n", i);
1308 return -EINVAL;
1309 }
1310 *out_num += ret;
1311 }
1312 } while ((i = next_desc(&desc)) != -1);
1313
1314 /* On success, increment avail index. */
1315 vq->last_avail_idx++;
1316
1317 /* Assume notifications from guest are disabled at this point,
1318 * if they aren't we would need to update avail_event index. */
1319 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1320 return head;
1321 }
1322 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
1323
1324 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1325 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1326 {
1327 vq->last_avail_idx -= n;
1328 }
1329 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
1330
1331 /* After we've used one of their buffers, we tell them about it. We'll then
1332 * want to notify the guest, using eventfd. */
1333 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1334 {
1335 struct vring_used_elem heads = { head, len };
1336
1337 return vhost_add_used_n(vq, &heads, 1);
1338 }
1339 EXPORT_SYMBOL_GPL(vhost_add_used);
1340
1341 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1342 struct vring_used_elem *heads,
1343 unsigned count)
1344 {
1345 struct vring_used_elem __user *used;
1346 u16 old, new;
1347 int start;
1348
1349 start = vq->last_used_idx % vq->num;
1350 used = vq->used->ring + start;
1351 if (count == 1) {
1352 if (__put_user(heads[0].id, &used->id)) {
1353 vq_err(vq, "Failed to write used id");
1354 return -EFAULT;
1355 }
1356 if (__put_user(heads[0].len, &used->len)) {
1357 vq_err(vq, "Failed to write used len");
1358 return -EFAULT;
1359 }
1360 } else if (__copy_to_user(used, heads, count * sizeof *used)) {
1361 vq_err(vq, "Failed to write used");
1362 return -EFAULT;
1363 }
1364 if (unlikely(vq->log_used)) {
1365 /* Make sure data is seen before log. */
1366 smp_wmb();
1367 /* Log used ring entry write. */
1368 log_write(vq->log_base,
1369 vq->log_addr +
1370 ((void __user *)used - (void __user *)vq->used),
1371 count * sizeof *used);
1372 }
1373 old = vq->last_used_idx;
1374 new = (vq->last_used_idx += count);
1375 /* If the driver never bothers to signal in a very long while,
1376 * used index might wrap around. If that happens, invalidate
1377 * signalled_used index we stored. TODO: make sure driver
1378 * signals at least once in 2^16 and remove this. */
1379 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1380 vq->signalled_used_valid = false;
1381 return 0;
1382 }
1383
1384 /* After we've used one of their buffers, we tell them about it. We'll then
1385 * want to notify the guest, using eventfd. */
1386 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1387 unsigned count)
1388 {
1389 int start, n, r;
1390
1391 start = vq->last_used_idx % vq->num;
1392 n = vq->num - start;
1393 if (n < count) {
1394 r = __vhost_add_used_n(vq, heads, n);
1395 if (r < 0)
1396 return r;
1397 heads += n;
1398 count -= n;
1399 }
1400 r = __vhost_add_used_n(vq, heads, count);
1401
1402 /* Make sure buffer is written before we update index. */
1403 smp_wmb();
1404 if (put_user(vq->last_used_idx, &vq->used->idx)) {
1405 vq_err(vq, "Failed to increment used idx");
1406 return -EFAULT;
1407 }
1408 if (unlikely(vq->log_used)) {
1409 /* Log used index update. */
1410 log_write(vq->log_base,
1411 vq->log_addr + offsetof(struct vring_used, idx),
1412 sizeof vq->used->idx);
1413 if (vq->log_ctx)
1414 eventfd_signal(vq->log_ctx, 1);
1415 }
1416 return r;
1417 }
1418 EXPORT_SYMBOL_GPL(vhost_add_used_n);
1419
1420 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1421 {
1422 __u16 old, new, event;
1423 bool v;
1424 /* Flush out used index updates. This is paired
1425 * with the barrier that the Guest executes when enabling
1426 * interrupts. */
1427 smp_mb();
1428
1429 if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1430 unlikely(vq->avail_idx == vq->last_avail_idx))
1431 return true;
1432
1433 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1434 __u16 flags;
1435 if (__get_user(flags, &vq->avail->flags)) {
1436 vq_err(vq, "Failed to get flags");
1437 return true;
1438 }
1439 return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
1440 }
1441 old = vq->signalled_used;
1442 v = vq->signalled_used_valid;
1443 new = vq->signalled_used = vq->last_used_idx;
1444 vq->signalled_used_valid = true;
1445
1446 if (unlikely(!v))
1447 return true;
1448
1449 if (get_user(event, vhost_used_event(vq))) {
1450 vq_err(vq, "Failed to get used event idx");
1451 return true;
1452 }
1453 return vring_need_event(event, new, old);
1454 }
1455
1456 /* This actually signals the guest, using eventfd. */
1457 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1458 {
1459 /* Signal the Guest tell them we used something up. */
1460 if (vq->call_ctx && vhost_notify(dev, vq))
1461 eventfd_signal(vq->call_ctx, 1);
1462 }
1463 EXPORT_SYMBOL_GPL(vhost_signal);
1464
1465 /* And here's the combo meal deal. Supersize me! */
1466 void vhost_add_used_and_signal(struct vhost_dev *dev,
1467 struct vhost_virtqueue *vq,
1468 unsigned int head, int len)
1469 {
1470 vhost_add_used(vq, head, len);
1471 vhost_signal(dev, vq);
1472 }
1473 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
1474
1475 /* multi-buffer version of vhost_add_used_and_signal */
1476 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1477 struct vhost_virtqueue *vq,
1478 struct vring_used_elem *heads, unsigned count)
1479 {
1480 vhost_add_used_n(vq, heads, count);
1481 vhost_signal(dev, vq);
1482 }
1483 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
1484
1485 /* OK, now we need to know about added descriptors. */
1486 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1487 {
1488 u16 avail_idx;
1489 int r;
1490
1491 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1492 return false;
1493 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1494 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1495 r = vhost_update_used_flags(vq);
1496 if (r) {
1497 vq_err(vq, "Failed to enable notification at %p: %d\n",
1498 &vq->used->flags, r);
1499 return false;
1500 }
1501 } else {
1502 r = vhost_update_avail_event(vq, vq->avail_idx);
1503 if (r) {
1504 vq_err(vq, "Failed to update avail event index at %p: %d\n",
1505 vhost_avail_event(vq), r);
1506 return false;
1507 }
1508 }
1509 /* They could have slipped one in as we were doing that: make
1510 * sure it's written, then check again. */
1511 smp_mb();
1512 r = __get_user(avail_idx, &vq->avail->idx);
1513 if (r) {
1514 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1515 &vq->avail->idx, r);
1516 return false;
1517 }
1518
1519 return avail_idx != vq->avail_idx;
1520 }
1521 EXPORT_SYMBOL_GPL(vhost_enable_notify);
1522
1523 /* We don't need to be notified again. */
1524 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1525 {
1526 int r;
1527
1528 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1529 return;
1530 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1531 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1532 r = vhost_update_used_flags(vq);
1533 if (r)
1534 vq_err(vq, "Failed to enable notification at %p: %d\n",
1535 &vq->used->flags, r);
1536 }
1537 }
1538 EXPORT_SYMBOL_GPL(vhost_disable_notify);
1539
1540 static int __init vhost_init(void)
1541 {
1542 return 0;
1543 }
1544
1545 static void __exit vhost_exit(void)
1546 {
1547 }
1548
1549 module_init(vhost_init);
1550 module_exit(vhost_exit);
1551
1552 MODULE_VERSION("0.0.1");
1553 MODULE_LICENSE("GPL v2");
1554 MODULE_AUTHOR("Michael S. Tsirkin");
1555 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
Linux with added FPC-III support