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Linux 4.1.16
[linux/fpc-iii.git] / drivers / vhost / vhost.c
blobfa49d3294cd52a69fa2c2f521553ced74be8104c
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/poll.h>
22 #include <linux/file.h>
23 #include <linux/highmem.h>
24 #include <linux/slab.h>
25 #include <linux/kthread.h>
26 #include <linux/cgroup.h>
27 #include <linux/module.h>
28
29 #include "vhost.h"
30
31 enum {
32 VHOST_MEMORY_MAX_NREGIONS = 64,
33 VHOST_MEMORY_F_LOG = 0x1,
34 };
35
36 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
37 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
38
39 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
40 poll_table *pt)
41 {
42 struct vhost_poll *poll;
43
44 poll = container_of(pt, struct vhost_poll, table);
45 poll->wqh = wqh;
46 add_wait_queue(wqh, &poll->wait);
47 }
48
49 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
50 void *key)
51 {
52 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
53
54 if (!((unsigned long)key & poll->mask))
55 return 0;
56
57 vhost_poll_queue(poll);
58 return 0;
59 }
60
61 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
62 {
63 INIT_LIST_HEAD(&work->node);
64 work->fn = fn;
65 init_waitqueue_head(&work->done);
66 work->flushing = 0;
67 work->queue_seq = work->done_seq = 0;
68 }
69 EXPORT_SYMBOL_GPL(vhost_work_init);
70
71 /* Init poll structure */
72 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
73 unsigned long mask, struct vhost_dev *dev)
74 {
75 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
76 init_poll_funcptr(&poll->table, vhost_poll_func);
77 poll->mask = mask;
78 poll->dev = dev;
79 poll->wqh = NULL;
80
81 vhost_work_init(&poll->work, fn);
82 }
83 EXPORT_SYMBOL_GPL(vhost_poll_init);
84
85 /* Start polling a file. We add ourselves to file's wait queue. The caller must
86 * keep a reference to a file until after vhost_poll_stop is called. */
87 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
88 {
89 unsigned long mask;
90 int ret = 0;
91
92 if (poll->wqh)
93 return 0;
94
95 mask = file->f_op->poll(file, &poll->table);
96 if (mask)
97 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
98 if (mask & POLLERR) {
99 if (poll->wqh)
100 remove_wait_queue(poll->wqh, &poll->wait);
101 ret = -EINVAL;
102 }
103
104 return ret;
105 }
106 EXPORT_SYMBOL_GPL(vhost_poll_start);
107
108 /* Stop polling a file. After this function returns, it becomes safe to drop the
109 * file reference. You must also flush afterwards. */
110 void vhost_poll_stop(struct vhost_poll *poll)
111 {
112 if (poll->wqh) {
113 remove_wait_queue(poll->wqh, &poll->wait);
114 poll->wqh = NULL;
115 }
116 }
117 EXPORT_SYMBOL_GPL(vhost_poll_stop);
118
119 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
120 unsigned seq)
121 {
122 int left;
123
124 spin_lock_irq(&dev->work_lock);
125 left = seq - work->done_seq;
126 spin_unlock_irq(&dev->work_lock);
127 return left <= 0;
128 }
129
130 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
131 {
132 unsigned seq;
133 int flushing;
134
135 spin_lock_irq(&dev->work_lock);
136 seq = work->queue_seq;
137 work->flushing++;
138 spin_unlock_irq(&dev->work_lock);
139 wait_event(work->done, vhost_work_seq_done(dev, work, seq));
140 spin_lock_irq(&dev->work_lock);
141 flushing = --work->flushing;
142 spin_unlock_irq(&dev->work_lock);
143 BUG_ON(flushing < 0);
144 }
145 EXPORT_SYMBOL_GPL(vhost_work_flush);
146
147 /* Flush any work that has been scheduled. When calling this, don't hold any
148 * locks that are also used by the callback. */
149 void vhost_poll_flush(struct vhost_poll *poll)
150 {
151 vhost_work_flush(poll->dev, &poll->work);
152 }
153 EXPORT_SYMBOL_GPL(vhost_poll_flush);
154
155 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
156 {
157 unsigned long flags;
158
159 spin_lock_irqsave(&dev->work_lock, flags);
160 if (list_empty(&work->node)) {
161 list_add_tail(&work->node, &dev->work_list);
162 work->queue_seq++;
163 spin_unlock_irqrestore(&dev->work_lock, flags);
164 wake_up_process(dev->worker);
165 } else {
166 spin_unlock_irqrestore(&dev->work_lock, flags);
167 }
168 }
169 EXPORT_SYMBOL_GPL(vhost_work_queue);
170
171 void vhost_poll_queue(struct vhost_poll *poll)
172 {
173 vhost_work_queue(poll->dev, &poll->work);
174 }
175 EXPORT_SYMBOL_GPL(vhost_poll_queue);
176
177 static void vhost_vq_reset(struct vhost_dev *dev,
178 struct vhost_virtqueue *vq)
179 {
180 vq->num = 1;
181 vq->desc = NULL;
182 vq->avail = NULL;
183 vq->used = NULL;
184 vq->last_avail_idx = 0;
185 vq->avail_idx = 0;
186 vq->last_used_idx = 0;
187 vq->signalled_used = 0;
188 vq->signalled_used_valid = false;
189 vq->used_flags = 0;
190 vq->log_used = false;
191 vq->log_addr = -1ull;
192 vq->private_data = NULL;
193 vq->acked_features = 0;
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 vq->memory = NULL;
202 }
203
204 static int vhost_worker(void *data)
205 {
206 struct vhost_dev *dev = data;
207 struct vhost_work *work = NULL;
208 unsigned uninitialized_var(seq);
209 mm_segment_t oldfs = get_fs();
210
211 set_fs(USER_DS);
212 use_mm(dev->mm);
213
214 for (;;) {
215 /* mb paired w/ kthread_stop */
216 set_current_state(TASK_INTERRUPTIBLE);
217
218 spin_lock_irq(&dev->work_lock);
219 if (work) {
220 work->done_seq = seq;
221 if (work->flushing)
222 wake_up_all(&work->done);
223 }
224
225 if (kthread_should_stop()) {
226 spin_unlock_irq(&dev->work_lock);
227 __set_current_state(TASK_RUNNING);
228 break;
229 }
230 if (!list_empty(&dev->work_list)) {
231 work = list_first_entry(&dev->work_list,
232 struct vhost_work, node);
233 list_del_init(&work->node);
234 seq = work->queue_seq;
235 } else
236 work = NULL;
237 spin_unlock_irq(&dev->work_lock);
238
239 if (work) {
240 __set_current_state(TASK_RUNNING);
241 work->fn(work);
242 if (need_resched())
243 schedule();
244 } else
245 schedule();
246
247 }
248 unuse_mm(dev->mm);
249 set_fs(oldfs);
250 return 0;
251 }
252
253 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
254 {
255 kfree(vq->indirect);
256 vq->indirect = NULL;
257 kfree(vq->log);
258 vq->log = NULL;
259 kfree(vq->heads);
260 vq->heads = NULL;
261 }
262
263 /* Helper to allocate iovec buffers for all vqs. */
264 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
265 {
266 struct vhost_virtqueue *vq;
267 int i;
268
269 for (i = 0; i < dev->nvqs; ++i) {
270 vq = dev->vqs[i];
271 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
272 GFP_KERNEL);
273 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
274 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
275 if (!vq->indirect || !vq->log || !vq->heads)
276 goto err_nomem;
277 }
278 return 0;
279
280 err_nomem:
281 for (; i >= 0; --i)
282 vhost_vq_free_iovecs(dev->vqs[i]);
283 return -ENOMEM;
284 }
285
286 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
287 {
288 int i;
289
290 for (i = 0; i < dev->nvqs; ++i)
291 vhost_vq_free_iovecs(dev->vqs[i]);
292 }
293
294 void vhost_dev_init(struct vhost_dev *dev,
295 struct vhost_virtqueue **vqs, int nvqs)
296 {
297 struct vhost_virtqueue *vq;
298 int i;
299
300 dev->vqs = vqs;
301 dev->nvqs = nvqs;
302 mutex_init(&dev->mutex);
303 dev->log_ctx = NULL;
304 dev->log_file = NULL;
305 dev->memory = NULL;
306 dev->mm = NULL;
307 spin_lock_init(&dev->work_lock);
308 INIT_LIST_HEAD(&dev->work_list);
309 dev->worker = NULL;
310
311 for (i = 0; i < dev->nvqs; ++i) {
312 vq = dev->vqs[i];
313 vq->log = NULL;
314 vq->indirect = NULL;
315 vq->heads = NULL;
316 vq->dev = dev;
317 mutex_init(&vq->mutex);
318 vhost_vq_reset(dev, vq);
319 if (vq->handle_kick)
320 vhost_poll_init(&vq->poll, vq->handle_kick,
321 POLLIN, dev);
322 }
323 }
324 EXPORT_SYMBOL_GPL(vhost_dev_init);
325
326 /* Caller should have device mutex */
327 long vhost_dev_check_owner(struct vhost_dev *dev)
328 {
329 /* Are you the owner? If not, I don't think you mean to do that */
330 return dev->mm == current->mm ? 0 : -EPERM;
331 }
332 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
333
334 struct vhost_attach_cgroups_struct {
335 struct vhost_work work;
336 struct task_struct *owner;
337 int ret;
338 };
339
340 static void vhost_attach_cgroups_work(struct vhost_work *work)
341 {
342 struct vhost_attach_cgroups_struct *s;
343
344 s = container_of(work, struct vhost_attach_cgroups_struct, work);
345 s->ret = cgroup_attach_task_all(s->owner, current);
346 }
347
348 static int vhost_attach_cgroups(struct vhost_dev *dev)
349 {
350 struct vhost_attach_cgroups_struct attach;
351
352 attach.owner = current;
353 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
354 vhost_work_queue(dev, &attach.work);
355 vhost_work_flush(dev, &attach.work);
356 return attach.ret;
357 }
358
359 /* Caller should have device mutex */
360 bool vhost_dev_has_owner(struct vhost_dev *dev)
361 {
362 return dev->mm;
363 }
364 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
365
366 /* Caller should have device mutex */
367 long vhost_dev_set_owner(struct vhost_dev *dev)
368 {
369 struct task_struct *worker;
370 int err;
371
372 /* Is there an owner already? */
373 if (vhost_dev_has_owner(dev)) {
374 err = -EBUSY;
375 goto err_mm;
376 }
377
378 /* No owner, become one */
379 dev->mm = get_task_mm(current);
380 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
381 if (IS_ERR(worker)) {
382 err = PTR_ERR(worker);
383 goto err_worker;
384 }
385
386 dev->worker = worker;
387 wake_up_process(worker); /* avoid contributing to loadavg */
388
389 err = vhost_attach_cgroups(dev);
390 if (err)
391 goto err_cgroup;
392
393 err = vhost_dev_alloc_iovecs(dev);
394 if (err)
395 goto err_cgroup;
396
397 return 0;
398 err_cgroup:
399 kthread_stop(worker);
400 dev->worker = NULL;
401 err_worker:
402 if (dev->mm)
403 mmput(dev->mm);
404 dev->mm = NULL;
405 err_mm:
406 return err;
407 }
408 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
409
410 struct vhost_memory *vhost_dev_reset_owner_prepare(void)
411 {
412 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
413 }
414 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
415
416 /* Caller should have device mutex */
417 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory)
418 {
419 int i;
420
421 vhost_dev_cleanup(dev, true);
422
423 /* Restore memory to default empty mapping. */
424 memory->nregions = 0;
425 dev->memory = memory;
426 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
427 * VQs aren't running.
428 */
429 for (i = 0; i < dev->nvqs; ++i)
430 dev->vqs[i]->memory = memory;
431 }
432 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
433
434 void vhost_dev_stop(struct vhost_dev *dev)
435 {
436 int i;
437
438 for (i = 0; i < dev->nvqs; ++i) {
439 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
440 vhost_poll_stop(&dev->vqs[i]->poll);
441 vhost_poll_flush(&dev->vqs[i]->poll);
442 }
443 }
444 }
445 EXPORT_SYMBOL_GPL(vhost_dev_stop);
446
447 /* Caller should have device mutex if and only if locked is set */
448 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
449 {
450 int i;
451
452 for (i = 0; i < dev->nvqs; ++i) {
453 if (dev->vqs[i]->error_ctx)
454 eventfd_ctx_put(dev->vqs[i]->error_ctx);
455 if (dev->vqs[i]->error)
456 fput(dev->vqs[i]->error);
457 if (dev->vqs[i]->kick)
458 fput(dev->vqs[i]->kick);
459 if (dev->vqs[i]->call_ctx)
460 eventfd_ctx_put(dev->vqs[i]->call_ctx);
461 if (dev->vqs[i]->call)
462 fput(dev->vqs[i]->call);
463 vhost_vq_reset(dev, dev->vqs[i]);
464 }
465 vhost_dev_free_iovecs(dev);
466 if (dev->log_ctx)
467 eventfd_ctx_put(dev->log_ctx);
468 dev->log_ctx = NULL;
469 if (dev->log_file)
470 fput(dev->log_file);
471 dev->log_file = NULL;
472 /* No one will access memory at this point */
473 kfree(dev->memory);
474 dev->memory = NULL;
475 WARN_ON(!list_empty(&dev->work_list));
476 if (dev->worker) {
477 kthread_stop(dev->worker);
478 dev->worker = NULL;
479 }
480 if (dev->mm)
481 mmput(dev->mm);
482 dev->mm = NULL;
483 }
484 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
485
486 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
487 {
488 u64 a = addr / VHOST_PAGE_SIZE / 8;
489
490 /* Make sure 64 bit math will not overflow. */
491 if (a > ULONG_MAX - (unsigned long)log_base ||
492 a + (unsigned long)log_base > ULONG_MAX)
493 return 0;
494
495 return access_ok(VERIFY_WRITE, log_base + a,
496 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
497 }
498
499 /* Caller should have vq mutex and device mutex. */
500 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
501 int log_all)
502 {
503 int i;
504
505 if (!mem)
506 return 0;
507
508 for (i = 0; i < mem->nregions; ++i) {
509 struct vhost_memory_region *m = mem->regions + i;
510 unsigned long a = m->userspace_addr;
511 if (m->memory_size > ULONG_MAX)
512 return 0;
513 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
514 m->memory_size))
515 return 0;
516 else if (log_all && !log_access_ok(log_base,
517 m->guest_phys_addr,
518 m->memory_size))
519 return 0;
520 }
521 return 1;
522 }
523
524 /* Can we switch to this memory table? */
525 /* Caller should have device mutex but not vq mutex */
526 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
527 int log_all)
528 {
529 int i;
530
531 for (i = 0; i < d->nvqs; ++i) {
532 int ok;
533 bool log;
534
535 mutex_lock(&d->vqs[i]->mutex);
536 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
537 /* If ring is inactive, will check when it's enabled. */
538 if (d->vqs[i]->private_data)
539 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log);
540 else
541 ok = 1;
542 mutex_unlock(&d->vqs[i]->mutex);
543 if (!ok)
544 return 0;
545 }
546 return 1;
547 }
548
549 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
550 struct vring_desc __user *desc,
551 struct vring_avail __user *avail,
552 struct vring_used __user *used)
553 {
554 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
555 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
556 access_ok(VERIFY_READ, avail,
557 sizeof *avail + num * sizeof *avail->ring + s) &&
558 access_ok(VERIFY_WRITE, used,
559 sizeof *used + num * sizeof *used->ring + s);
560 }
561
562 /* Can we log writes? */
563 /* Caller should have device mutex but not vq mutex */
564 int vhost_log_access_ok(struct vhost_dev *dev)
565 {
566 return memory_access_ok(dev, dev->memory, 1);
567 }
568 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
569
570 /* Verify access for write logging. */
571 /* Caller should have vq mutex and device mutex */
572 static int vq_log_access_ok(struct vhost_virtqueue *vq,
573 void __user *log_base)
574 {
575 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
576
577 return vq_memory_access_ok(log_base, vq->memory,
578 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
579 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
580 sizeof *vq->used +
581 vq->num * sizeof *vq->used->ring + s));
582 }
583
584 /* Can we start vq? */
585 /* Caller should have vq mutex and device mutex */
586 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
587 {
588 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
589 vq_log_access_ok(vq, vq->log_base);
590 }
591 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
592
593 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
594 {
595 struct vhost_memory mem, *newmem, *oldmem;
596 unsigned long size = offsetof(struct vhost_memory, regions);
597 int i;
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, 0)) {
617 kfree(newmem);
618 return -EFAULT;
619 }
620 oldmem = d->memory;
621 d->memory = newmem;
622
623 /* All memory accesses are done under some VQ mutex. */
624 for (i = 0; i < d->nvqs; ++i) {
625 mutex_lock(&d->vqs[i]->mutex);
626 d->vqs[i]->memory = newmem;
627 mutex_unlock(&d->vqs[i]->mutex);
628 }
629 kfree(oldmem);
630 return 0;
631 }
632
633 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
634 {
635 struct file *eventfp, *filep = NULL;
636 bool pollstart = false, pollstop = false;
637 struct eventfd_ctx *ctx = NULL;
638 u32 __user *idxp = argp;
639 struct vhost_virtqueue *vq;
640 struct vhost_vring_state s;
641 struct vhost_vring_file f;
642 struct vhost_vring_addr a;
643 u32 idx;
644 long r;
645
646 r = get_user(idx, idxp);
647 if (r < 0)
648 return r;
649 if (idx >= d->nvqs)
650 return -ENOBUFS;
651
652 vq = d->vqs[idx];
653
654 mutex_lock(&vq->mutex);
655
656 switch (ioctl) {
657 case VHOST_SET_VRING_NUM:
658 /* Resizing ring with an active backend?
659 * You don't want to do that. */
660 if (vq->private_data) {
661 r = -EBUSY;
662 break;
663 }
664 if (copy_from_user(&s, argp, sizeof s)) {
665 r = -EFAULT;
666 break;
667 }
668 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
669 r = -EINVAL;
670 break;
671 }
672 vq->num = s.num;
673 break;
674 case VHOST_SET_VRING_BASE:
675 /* Moving base with an active backend?
676 * You don't want to do that. */
677 if (vq->private_data) {
678 r = -EBUSY;
679 break;
680 }
681 if (copy_from_user(&s, argp, sizeof s)) {
682 r = -EFAULT;
683 break;
684 }
685 if (s.num > 0xffff) {
686 r = -EINVAL;
687 break;
688 }
689 vq->last_avail_idx = s.num;
690 /* Forget the cached index value. */
691 vq->avail_idx = vq->last_avail_idx;
692 break;
693 case VHOST_GET_VRING_BASE:
694 s.index = idx;
695 s.num = vq->last_avail_idx;
696 if (copy_to_user(argp, &s, sizeof s))
697 r = -EFAULT;
698 break;
699 case VHOST_SET_VRING_ADDR:
700 if (copy_from_user(&a, argp, sizeof a)) {
701 r = -EFAULT;
702 break;
703 }
704 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
705 r = -EOPNOTSUPP;
706 break;
707 }
708 /* For 32bit, verify that the top 32bits of the user
709 data are set to zero. */
710 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
711 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
712 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
713 r = -EFAULT;
714 break;
715 }
716
717 /* Make sure it's safe to cast pointers to vring types. */
718 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
719 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
720 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
721 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
722 (a.log_guest_addr & (sizeof(u64) - 1))) {
723 r = -EINVAL;
724 break;
725 }
726
727 /* We only verify access here if backend is configured.
728 * If it is not, we don't as size might not have been setup.
729 * We will verify when backend is configured. */
730 if (vq->private_data) {
731 if (!vq_access_ok(vq, vq->num,
732 (void __user *)(unsigned long)a.desc_user_addr,
733 (void __user *)(unsigned long)a.avail_user_addr,
734 (void __user *)(unsigned long)a.used_user_addr)) {
735 r = -EINVAL;
736 break;
737 }
738
739 /* Also validate log access for used ring if enabled. */
740 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
741 !log_access_ok(vq->log_base, a.log_guest_addr,
742 sizeof *vq->used +
743 vq->num * sizeof *vq->used->ring)) {
744 r = -EINVAL;
745 break;
746 }
747 }
748
749 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
750 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
751 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
752 vq->log_addr = a.log_guest_addr;
753 vq->used = (void __user *)(unsigned long)a.used_user_addr;
754 break;
755 case VHOST_SET_VRING_KICK:
756 if (copy_from_user(&f, argp, sizeof f)) {
757 r = -EFAULT;
758 break;
759 }
760 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
761 if (IS_ERR(eventfp)) {
762 r = PTR_ERR(eventfp);
763 break;
764 }
765 if (eventfp != vq->kick) {
766 pollstop = (filep = vq->kick) != NULL;
767 pollstart = (vq->kick = eventfp) != NULL;
768 } else
769 filep = eventfp;
770 break;
771 case VHOST_SET_VRING_CALL:
772 if (copy_from_user(&f, argp, sizeof f)) {
773 r = -EFAULT;
774 break;
775 }
776 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
777 if (IS_ERR(eventfp)) {
778 r = PTR_ERR(eventfp);
779 break;
780 }
781 if (eventfp != vq->call) {
782 filep = vq->call;
783 ctx = vq->call_ctx;
784 vq->call = eventfp;
785 vq->call_ctx = eventfp ?
786 eventfd_ctx_fileget(eventfp) : NULL;
787 } else
788 filep = eventfp;
789 break;
790 case VHOST_SET_VRING_ERR:
791 if (copy_from_user(&f, argp, sizeof f)) {
792 r = -EFAULT;
793 break;
794 }
795 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
796 if (IS_ERR(eventfp)) {
797 r = PTR_ERR(eventfp);
798 break;
799 }
800 if (eventfp != vq->error) {
801 filep = vq->error;
802 vq->error = eventfp;
803 ctx = vq->error_ctx;
804 vq->error_ctx = eventfp ?
805 eventfd_ctx_fileget(eventfp) : NULL;
806 } else
807 filep = eventfp;
808 break;
809 default:
810 r = -ENOIOCTLCMD;
811 }
812
813 if (pollstop && vq->handle_kick)
814 vhost_poll_stop(&vq->poll);
815
816 if (ctx)
817 eventfd_ctx_put(ctx);
818 if (filep)
819 fput(filep);
820
821 if (pollstart && vq->handle_kick)
822 r = vhost_poll_start(&vq->poll, vq->kick);
823
824 mutex_unlock(&vq->mutex);
825
826 if (pollstop && vq->handle_kick)
827 vhost_poll_flush(&vq->poll);
828 return r;
829 }
830 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
831
832 /* Caller must have device mutex */
833 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
834 {
835 struct file *eventfp, *filep = NULL;
836 struct eventfd_ctx *ctx = NULL;
837 u64 p;
838 long r;
839 int i, fd;
840
841 /* If you are not the owner, you can become one */
842 if (ioctl == VHOST_SET_OWNER) {
843 r = vhost_dev_set_owner(d);
844 goto done;
845 }
846
847 /* You must be the owner to do anything else */
848 r = vhost_dev_check_owner(d);
849 if (r)
850 goto done;
851
852 switch (ioctl) {
853 case VHOST_SET_MEM_TABLE:
854 r = vhost_set_memory(d, argp);
855 break;
856 case VHOST_SET_LOG_BASE:
857 if (copy_from_user(&p, argp, sizeof p)) {
858 r = -EFAULT;
859 break;
860 }
861 if ((u64)(unsigned long)p != p) {
862 r = -EFAULT;
863 break;
864 }
865 for (i = 0; i < d->nvqs; ++i) {
866 struct vhost_virtqueue *vq;
867 void __user *base = (void __user *)(unsigned long)p;
868 vq = d->vqs[i];
869 mutex_lock(&vq->mutex);
870 /* If ring is inactive, will check when it's enabled. */
871 if (vq->private_data && !vq_log_access_ok(vq, base))
872 r = -EFAULT;
873 else
874 vq->log_base = base;
875 mutex_unlock(&vq->mutex);
876 }
877 break;
878 case VHOST_SET_LOG_FD:
879 r = get_user(fd, (int __user *)argp);
880 if (r < 0)
881 break;
882 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
883 if (IS_ERR(eventfp)) {
884 r = PTR_ERR(eventfp);
885 break;
886 }
887 if (eventfp != d->log_file) {
888 filep = d->log_file;
889 d->log_file = eventfp;
890 ctx = d->log_ctx;
891 d->log_ctx = eventfp ?
892 eventfd_ctx_fileget(eventfp) : NULL;
893 } else
894 filep = eventfp;
895 for (i = 0; i < d->nvqs; ++i) {
896 mutex_lock(&d->vqs[i]->mutex);
897 d->vqs[i]->log_ctx = d->log_ctx;
898 mutex_unlock(&d->vqs[i]->mutex);
899 }
900 if (ctx)
901 eventfd_ctx_put(ctx);
902 if (filep)
903 fput(filep);
904 break;
905 default:
906 r = -ENOIOCTLCMD;
907 break;
908 }
909 done:
910 return r;
911 }
912 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
913
914 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
915 __u64 addr, __u32 len)
916 {
917 struct vhost_memory_region *reg;
918 int i;
919
920 /* linear search is not brilliant, but we really have on the order of 6
921 * regions in practice */
922 for (i = 0; i < mem->nregions; ++i) {
923 reg = mem->regions + i;
924 if (reg->guest_phys_addr <= addr &&
925 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
926 return reg;
927 }
928 return NULL;
929 }
930
931 /* TODO: This is really inefficient. We need something like get_user()
932 * (instruction directly accesses the data, with an exception table entry
933 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
934 */
935 static int set_bit_to_user(int nr, void __user *addr)
936 {
937 unsigned long log = (unsigned long)addr;
938 struct page *page;
939 void *base;
940 int bit = nr + (log % PAGE_SIZE) * 8;
941 int r;
942
943 r = get_user_pages_fast(log, 1, 1, &page);
944 if (r < 0)
945 return r;
946 BUG_ON(r != 1);
947 base = kmap_atomic(page);
948 set_bit(bit, base);
949 kunmap_atomic(base);
950 set_page_dirty_lock(page);
951 put_page(page);
952 return 0;
953 }
954
955 static int log_write(void __user *log_base,
956 u64 write_address, u64 write_length)
957 {
958 u64 write_page = write_address / VHOST_PAGE_SIZE;
959 int r;
960
961 if (!write_length)
962 return 0;
963 write_length += write_address % VHOST_PAGE_SIZE;
964 for (;;) {
965 u64 base = (u64)(unsigned long)log_base;
966 u64 log = base + write_page / 8;
967 int bit = write_page % 8;
968 if ((u64)(unsigned long)log != log)
969 return -EFAULT;
970 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
971 if (r < 0)
972 return r;
973 if (write_length <= VHOST_PAGE_SIZE)
974 break;
975 write_length -= VHOST_PAGE_SIZE;
976 write_page += 1;
977 }
978 return r;
979 }
980
981 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
982 unsigned int log_num, u64 len)
983 {
984 int i, r;
985
986 /* Make sure data written is seen before log. */
987 smp_wmb();
988 for (i = 0; i < log_num; ++i) {
989 u64 l = min(log[i].len, len);
990 r = log_write(vq->log_base, log[i].addr, l);
991 if (r < 0)
992 return r;
993 len -= l;
994 if (!len) {
995 if (vq->log_ctx)
996 eventfd_signal(vq->log_ctx, 1);
997 return 0;
998 }
999 }
1000 /* Length written exceeds what we have stored. This is a bug. */
1001 BUG();
1002 return 0;
1003 }
1004 EXPORT_SYMBOL_GPL(vhost_log_write);
1005
1006 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1007 {
1008 void __user *used;
1009 if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0)
1010 return -EFAULT;
1011 if (unlikely(vq->log_used)) {
1012 /* Make sure the flag is seen before log. */
1013 smp_wmb();
1014 /* Log used flag write. */
1015 used = &vq->used->flags;
1016 log_write(vq->log_base, vq->log_addr +
1017 (used - (void __user *)vq->used),
1018 sizeof vq->used->flags);
1019 if (vq->log_ctx)
1020 eventfd_signal(vq->log_ctx, 1);
1021 }
1022 return 0;
1023 }
1024
1025 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1026 {
1027 if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq)))
1028 return -EFAULT;
1029 if (unlikely(vq->log_used)) {
1030 void __user *used;
1031 /* Make sure the event is seen before log. */
1032 smp_wmb();
1033 /* Log avail event write */
1034 used = vhost_avail_event(vq);
1035 log_write(vq->log_base, vq->log_addr +
1036 (used - (void __user *)vq->used),
1037 sizeof *vhost_avail_event(vq));
1038 if (vq->log_ctx)
1039 eventfd_signal(vq->log_ctx, 1);
1040 }
1041 return 0;
1042 }
1043
1044 int vhost_init_used(struct vhost_virtqueue *vq)
1045 {
1046 __virtio16 last_used_idx;
1047 int r;
1048 if (!vq->private_data)
1049 return 0;
1050
1051 r = vhost_update_used_flags(vq);
1052 if (r)
1053 return r;
1054 vq->signalled_used_valid = false;
1055 if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx))
1056 return -EFAULT;
1057 r = __get_user(last_used_idx, &vq->used->idx);
1058 if (r)
1059 return r;
1060 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1061 return 0;
1062 }
1063 EXPORT_SYMBOL_GPL(vhost_init_used);
1064
1065 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1066 struct iovec iov[], int iov_size)
1067 {
1068 const struct vhost_memory_region *reg;
1069 struct vhost_memory *mem;
1070 struct iovec *_iov;
1071 u64 s = 0;
1072 int ret = 0;
1073
1074 mem = vq->memory;
1075 while ((u64)len > s) {
1076 u64 size;
1077 if (unlikely(ret >= iov_size)) {
1078 ret = -ENOBUFS;
1079 break;
1080 }
1081 reg = find_region(mem, addr, len);
1082 if (unlikely(!reg)) {
1083 ret = -EFAULT;
1084 break;
1085 }
1086 _iov = iov + ret;
1087 size = reg->memory_size - addr + reg->guest_phys_addr;
1088 _iov->iov_len = min((u64)len - s, size);
1089 _iov->iov_base = (void __user *)(unsigned long)
1090 (reg->userspace_addr + addr - reg->guest_phys_addr);
1091 s += size;
1092 addr += size;
1093 ++ret;
1094 }
1095
1096 return ret;
1097 }
1098
1099 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1100 * function returns the next descriptor in the chain,
1101 * or -1U if we're at the end. */
1102 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1103 {
1104 unsigned int next;
1105
1106 /* If this descriptor says it doesn't chain, we're done. */
1107 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1108 return -1U;
1109
1110 /* Check they're not leading us off end of descriptors. */
1111 next = vhost16_to_cpu(vq, desc->next);
1112 /* Make sure compiler knows to grab that: we don't want it changing! */
1113 /* We will use the result as an index in an array, so most
1114 * architectures only need a compiler barrier here. */
1115 read_barrier_depends();
1116
1117 return next;
1118 }
1119
1120 static int get_indirect(struct vhost_virtqueue *vq,
1121 struct iovec iov[], unsigned int iov_size,
1122 unsigned int *out_num, unsigned int *in_num,
1123 struct vhost_log *log, unsigned int *log_num,
1124 struct vring_desc *indirect)
1125 {
1126 struct vring_desc desc;
1127 unsigned int i = 0, count, found = 0;
1128 u32 len = vhost32_to_cpu(vq, indirect->len);
1129 struct iov_iter from;
1130 int ret;
1131
1132 /* Sanity check */
1133 if (unlikely(len % sizeof desc)) {
1134 vq_err(vq, "Invalid length in indirect descriptor: "
1135 "len 0x%llx not multiple of 0x%zx\n",
1136 (unsigned long long)len,
1137 sizeof desc);
1138 return -EINVAL;
1139 }
1140
1141 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1142 UIO_MAXIOV);
1143 if (unlikely(ret < 0)) {
1144 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1145 return ret;
1146 }
1147 iov_iter_init(&from, READ, vq->indirect, ret, len);
1148
1149 /* We will use the result as an address to read from, so most
1150 * architectures only need a compiler barrier here. */
1151 read_barrier_depends();
1152
1153 count = len / sizeof desc;
1154 /* Buffers are chained via a 16 bit next field, so
1155 * we can have at most 2^16 of these. */
1156 if (unlikely(count > USHRT_MAX + 1)) {
1157 vq_err(vq, "Indirect buffer length too big: %d\n",
1158 indirect->len);
1159 return -E2BIG;
1160 }
1161
1162 do {
1163 unsigned iov_count = *in_num + *out_num;
1164 if (unlikely(++found > count)) {
1165 vq_err(vq, "Loop detected: last one at %u "
1166 "indirect size %u\n",
1167 i, count);
1168 return -EINVAL;
1169 }
1170 if (unlikely(copy_from_iter(&desc, sizeof(desc), &from) !=
1171 sizeof(desc))) {
1172 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1173 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1174 return -EINVAL;
1175 }
1176 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1177 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1178 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1179 return -EINVAL;
1180 }
1181
1182 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1183 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1184 iov_size - iov_count);
1185 if (unlikely(ret < 0)) {
1186 vq_err(vq, "Translation failure %d indirect idx %d\n",
1187 ret, i);
1188 return ret;
1189 }
1190 /* If this is an input descriptor, increment that count. */
1191 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
1192 *in_num += ret;
1193 if (unlikely(log)) {
1194 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1195 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1196 ++*log_num;
1197 }
1198 } else {
1199 /* If it's an output descriptor, they're all supposed
1200 * to come before any input descriptors. */
1201 if (unlikely(*in_num)) {
1202 vq_err(vq, "Indirect descriptor "
1203 "has out after in: idx %d\n", i);
1204 return -EINVAL;
1205 }
1206 *out_num += ret;
1207 }
1208 } while ((i = next_desc(vq, &desc)) != -1);
1209 return 0;
1210 }
1211
1212 /* This looks in the virtqueue and for the first available buffer, and converts
1213 * it to an iovec for convenient access. Since descriptors consist of some
1214 * number of output then some number of input descriptors, it's actually two
1215 * iovecs, but we pack them into one and note how many of each there were.
1216 *
1217 * This function returns the descriptor number found, or vq->num (which is
1218 * never a valid descriptor number) if none was found. A negative code is
1219 * returned on error. */
1220 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1221 struct iovec iov[], unsigned int iov_size,
1222 unsigned int *out_num, unsigned int *in_num,
1223 struct vhost_log *log, unsigned int *log_num)
1224 {
1225 struct vring_desc desc;
1226 unsigned int i, head, found = 0;
1227 u16 last_avail_idx;
1228 __virtio16 avail_idx;
1229 __virtio16 ring_head;
1230 int ret;
1231
1232 /* Check it isn't doing very strange things with descriptor numbers. */
1233 last_avail_idx = vq->last_avail_idx;
1234 if (unlikely(__get_user(avail_idx, &vq->avail->idx))) {
1235 vq_err(vq, "Failed to access avail idx at %p\n",
1236 &vq->avail->idx);
1237 return -EFAULT;
1238 }
1239 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1240
1241 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1242 vq_err(vq, "Guest moved used index from %u to %u",
1243 last_avail_idx, vq->avail_idx);
1244 return -EFAULT;
1245 }
1246
1247 /* If there's nothing new since last we looked, return invalid. */
1248 if (vq->avail_idx == last_avail_idx)
1249 return vq->num;
1250
1251 /* Only get avail ring entries after they have been exposed by guest. */
1252 smp_rmb();
1253
1254 /* Grab the next descriptor number they're advertising, and increment
1255 * the index we've seen. */
1256 if (unlikely(__get_user(ring_head,
1257 &vq->avail->ring[last_avail_idx % vq->num]))) {
1258 vq_err(vq, "Failed to read head: idx %d address %p\n",
1259 last_avail_idx,
1260 &vq->avail->ring[last_avail_idx % vq->num]);
1261 return -EFAULT;
1262 }
1263
1264 head = vhost16_to_cpu(vq, ring_head);
1265
1266 /* If their number is silly, that's an error. */
1267 if (unlikely(head >= vq->num)) {
1268 vq_err(vq, "Guest says index %u > %u is available",
1269 head, vq->num);
1270 return -EINVAL;
1271 }
1272
1273 /* When we start there are none of either input nor output. */
1274 *out_num = *in_num = 0;
1275 if (unlikely(log))
1276 *log_num = 0;
1277
1278 i = head;
1279 do {
1280 unsigned iov_count = *in_num + *out_num;
1281 if (unlikely(i >= vq->num)) {
1282 vq_err(vq, "Desc index is %u > %u, head = %u",
1283 i, vq->num, head);
1284 return -EINVAL;
1285 }
1286 if (unlikely(++found > vq->num)) {
1287 vq_err(vq, "Loop detected: last one at %u "
1288 "vq size %u head %u\n",
1289 i, vq->num, head);
1290 return -EINVAL;
1291 }
1292 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1293 if (unlikely(ret)) {
1294 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1295 i, vq->desc + i);
1296 return -EFAULT;
1297 }
1298 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
1299 ret = get_indirect(vq, iov, iov_size,
1300 out_num, in_num,
1301 log, log_num, &desc);
1302 if (unlikely(ret < 0)) {
1303 vq_err(vq, "Failure detected "
1304 "in indirect descriptor at idx %d\n", i);
1305 return ret;
1306 }
1307 continue;
1308 }
1309
1310 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1311 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1312 iov_size - iov_count);
1313 if (unlikely(ret < 0)) {
1314 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1315 ret, i);
1316 return ret;
1317 }
1318 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
1319 /* If this is an input descriptor,
1320 * increment that count. */
1321 *in_num += ret;
1322 if (unlikely(log)) {
1323 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1324 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1325 ++*log_num;
1326 }
1327 } else {
1328 /* If it's an output descriptor, they're all supposed
1329 * to come before any input descriptors. */
1330 if (unlikely(*in_num)) {
1331 vq_err(vq, "Descriptor has out after in: "
1332 "idx %d\n", i);
1333 return -EINVAL;
1334 }
1335 *out_num += ret;
1336 }
1337 } while ((i = next_desc(vq, &desc)) != -1);
1338
1339 /* On success, increment avail index. */
1340 vq->last_avail_idx++;
1341
1342 /* Assume notifications from guest are disabled at this point,
1343 * if they aren't we would need to update avail_event index. */
1344 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1345 return head;
1346 }
1347 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
1348
1349 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1350 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1351 {
1352 vq->last_avail_idx -= n;
1353 }
1354 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
1355
1356 /* After we've used one of their buffers, we tell them about it. We'll then
1357 * want to notify the guest, using eventfd. */
1358 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1359 {
1360 struct vring_used_elem heads = {
1361 cpu_to_vhost32(vq, head),
1362 cpu_to_vhost32(vq, len)
1363 };
1364
1365 return vhost_add_used_n(vq, &heads, 1);
1366 }
1367 EXPORT_SYMBOL_GPL(vhost_add_used);
1368
1369 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1370 struct vring_used_elem *heads,
1371 unsigned count)
1372 {
1373 struct vring_used_elem __user *used;
1374 u16 old, new;
1375 int start;
1376
1377 start = vq->last_used_idx % vq->num;
1378 used = vq->used->ring + start;
1379 if (count == 1) {
1380 if (__put_user(heads[0].id, &used->id)) {
1381 vq_err(vq, "Failed to write used id");
1382 return -EFAULT;
1383 }
1384 if (__put_user(heads[0].len, &used->len)) {
1385 vq_err(vq, "Failed to write used len");
1386 return -EFAULT;
1387 }
1388 } else if (__copy_to_user(used, heads, count * sizeof *used)) {
1389 vq_err(vq, "Failed to write used");
1390 return -EFAULT;
1391 }
1392 if (unlikely(vq->log_used)) {
1393 /* Make sure data is seen before log. */
1394 smp_wmb();
1395 /* Log used ring entry write. */
1396 log_write(vq->log_base,
1397 vq->log_addr +
1398 ((void __user *)used - (void __user *)vq->used),
1399 count * sizeof *used);
1400 }
1401 old = vq->last_used_idx;
1402 new = (vq->last_used_idx += count);
1403 /* If the driver never bothers to signal in a very long while,
1404 * used index might wrap around. If that happens, invalidate
1405 * signalled_used index we stored. TODO: make sure driver
1406 * signals at least once in 2^16 and remove this. */
1407 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1408 vq->signalled_used_valid = false;
1409 return 0;
1410 }
1411
1412 /* After we've used one of their buffers, we tell them about it. We'll then
1413 * want to notify the guest, using eventfd. */
1414 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1415 unsigned count)
1416 {
1417 int start, n, r;
1418
1419 start = vq->last_used_idx % vq->num;
1420 n = vq->num - start;
1421 if (n < count) {
1422 r = __vhost_add_used_n(vq, heads, n);
1423 if (r < 0)
1424 return r;
1425 heads += n;
1426 count -= n;
1427 }
1428 r = __vhost_add_used_n(vq, heads, count);
1429
1430 /* Make sure buffer is written before we update index. */
1431 smp_wmb();
1432 if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) {
1433 vq_err(vq, "Failed to increment used idx");
1434 return -EFAULT;
1435 }
1436 if (unlikely(vq->log_used)) {
1437 /* Log used index update. */
1438 log_write(vq->log_base,
1439 vq->log_addr + offsetof(struct vring_used, idx),
1440 sizeof vq->used->idx);
1441 if (vq->log_ctx)
1442 eventfd_signal(vq->log_ctx, 1);
1443 }
1444 return r;
1445 }
1446 EXPORT_SYMBOL_GPL(vhost_add_used_n);
1447
1448 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1449 {
1450 __u16 old, new;
1451 __virtio16 event;
1452 bool v;
1453 /* Flush out used index updates. This is paired
1454 * with the barrier that the Guest executes when enabling
1455 * interrupts. */
1456 smp_mb();
1457
1458 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1459 unlikely(vq->avail_idx == vq->last_avail_idx))
1460 return true;
1461
1462 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1463 __virtio16 flags;
1464 if (__get_user(flags, &vq->avail->flags)) {
1465 vq_err(vq, "Failed to get flags");
1466 return true;
1467 }
1468 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
1469 }
1470 old = vq->signalled_used;
1471 v = vq->signalled_used_valid;
1472 new = vq->signalled_used = vq->last_used_idx;
1473 vq->signalled_used_valid = true;
1474
1475 if (unlikely(!v))
1476 return true;
1477
1478 if (__get_user(event, vhost_used_event(vq))) {
1479 vq_err(vq, "Failed to get used event idx");
1480 return true;
1481 }
1482 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
1483 }
1484
1485 /* This actually signals the guest, using eventfd. */
1486 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1487 {
1488 /* Signal the Guest tell them we used something up. */
1489 if (vq->call_ctx && vhost_notify(dev, vq))
1490 eventfd_signal(vq->call_ctx, 1);
1491 }
1492 EXPORT_SYMBOL_GPL(vhost_signal);
1493
1494 /* And here's the combo meal deal. Supersize me! */
1495 void vhost_add_used_and_signal(struct vhost_dev *dev,
1496 struct vhost_virtqueue *vq,
1497 unsigned int head, int len)
1498 {
1499 vhost_add_used(vq, head, len);
1500 vhost_signal(dev, vq);
1501 }
1502 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
1503
1504 /* multi-buffer version of vhost_add_used_and_signal */
1505 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1506 struct vhost_virtqueue *vq,
1507 struct vring_used_elem *heads, unsigned count)
1508 {
1509 vhost_add_used_n(vq, heads, count);
1510 vhost_signal(dev, vq);
1511 }
1512 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
1513
1514 /* OK, now we need to know about added descriptors. */
1515 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1516 {
1517 __virtio16 avail_idx;
1518 int r;
1519
1520 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1521 return false;
1522 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1523 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1524 r = vhost_update_used_flags(vq);
1525 if (r) {
1526 vq_err(vq, "Failed to enable notification at %p: %d\n",
1527 &vq->used->flags, r);
1528 return false;
1529 }
1530 } else {
1531 r = vhost_update_avail_event(vq, vq->avail_idx);
1532 if (r) {
1533 vq_err(vq, "Failed to update avail event index at %p: %d\n",
1534 vhost_avail_event(vq), r);
1535 return false;
1536 }
1537 }
1538 /* They could have slipped one in as we were doing that: make
1539 * sure it's written, then check again. */
1540 smp_mb();
1541 r = __get_user(avail_idx, &vq->avail->idx);
1542 if (r) {
1543 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1544 &vq->avail->idx, r);
1545 return false;
1546 }
1547
1548 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
1549 }
1550 EXPORT_SYMBOL_GPL(vhost_enable_notify);
1551
1552 /* We don't need to be notified again. */
1553 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1554 {
1555 int r;
1556
1557 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1558 return;
1559 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1560 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1561 r = vhost_update_used_flags(vq);
1562 if (r)
1563 vq_err(vq, "Failed to enable notification at %p: %d\n",
1564 &vq->used->flags, r);
1565 }
1566 }
1567 EXPORT_SYMBOL_GPL(vhost_disable_notify);
1568
1569 static int __init vhost_init(void)
1570 {
1571 return 0;
1572 }
1573
1574 static void __exit vhost_exit(void)
1575 {
1576 }
1577
1578 module_init(vhost_init);
1579 module_exit(vhost_exit);
1580
1581 MODULE_VERSION("0.0.1");
1582 MODULE_LICENSE("GPL v2");
1583 MODULE_AUTHOR("Michael S. Tsirkin");
1584 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
Linux with added FPC-III support