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mm/zsmalloc: allocate exactly size of struct zs_pool
[linux/fpc-iii.git] / drivers / vhost / vhost.c
blobed71b5347a766ee26c95039638a028ece31b53de
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 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
717 (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
718 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
719 r = -EINVAL;
720 break;
721 }
722
723 /* We only verify access here if backend is configured.
724 * If it is not, we don't as size might not have been setup.
725 * We will verify when backend is configured. */
726 if (vq->private_data) {
727 if (!vq_access_ok(vq, vq->num,
728 (void __user *)(unsigned long)a.desc_user_addr,
729 (void __user *)(unsigned long)a.avail_user_addr,
730 (void __user *)(unsigned long)a.used_user_addr)) {
731 r = -EINVAL;
732 break;
733 }
734
735 /* Also validate log access for used ring if enabled. */
736 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
737 !log_access_ok(vq->log_base, a.log_guest_addr,
738 sizeof *vq->used +
739 vq->num * sizeof *vq->used->ring)) {
740 r = -EINVAL;
741 break;
742 }
743 }
744
745 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
746 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
747 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
748 vq->log_addr = a.log_guest_addr;
749 vq->used = (void __user *)(unsigned long)a.used_user_addr;
750 break;
751 case VHOST_SET_VRING_KICK:
752 if (copy_from_user(&f, argp, sizeof f)) {
753 r = -EFAULT;
754 break;
755 }
756 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
757 if (IS_ERR(eventfp)) {
758 r = PTR_ERR(eventfp);
759 break;
760 }
761 if (eventfp != vq->kick) {
762 pollstop = (filep = vq->kick) != NULL;
763 pollstart = (vq->kick = eventfp) != NULL;
764 } else
765 filep = eventfp;
766 break;
767 case VHOST_SET_VRING_CALL:
768 if (copy_from_user(&f, argp, sizeof f)) {
769 r = -EFAULT;
770 break;
771 }
772 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
773 if (IS_ERR(eventfp)) {
774 r = PTR_ERR(eventfp);
775 break;
776 }
777 if (eventfp != vq->call) {
778 filep = vq->call;
779 ctx = vq->call_ctx;
780 vq->call = eventfp;
781 vq->call_ctx = eventfp ?
782 eventfd_ctx_fileget(eventfp) : NULL;
783 } else
784 filep = eventfp;
785 break;
786 case VHOST_SET_VRING_ERR:
787 if (copy_from_user(&f, argp, sizeof f)) {
788 r = -EFAULT;
789 break;
790 }
791 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
792 if (IS_ERR(eventfp)) {
793 r = PTR_ERR(eventfp);
794 break;
795 }
796 if (eventfp != vq->error) {
797 filep = vq->error;
798 vq->error = eventfp;
799 ctx = vq->error_ctx;
800 vq->error_ctx = eventfp ?
801 eventfd_ctx_fileget(eventfp) : NULL;
802 } else
803 filep = eventfp;
804 break;
805 default:
806 r = -ENOIOCTLCMD;
807 }
808
809 if (pollstop && vq->handle_kick)
810 vhost_poll_stop(&vq->poll);
811
812 if (ctx)
813 eventfd_ctx_put(ctx);
814 if (filep)
815 fput(filep);
816
817 if (pollstart && vq->handle_kick)
818 r = vhost_poll_start(&vq->poll, vq->kick);
819
820 mutex_unlock(&vq->mutex);
821
822 if (pollstop && vq->handle_kick)
823 vhost_poll_flush(&vq->poll);
824 return r;
825 }
826 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
827
828 /* Caller must have device mutex */
829 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
830 {
831 struct file *eventfp, *filep = NULL;
832 struct eventfd_ctx *ctx = NULL;
833 u64 p;
834 long r;
835 int i, fd;
836
837 /* If you are not the owner, you can become one */
838 if (ioctl == VHOST_SET_OWNER) {
839 r = vhost_dev_set_owner(d);
840 goto done;
841 }
842
843 /* You must be the owner to do anything else */
844 r = vhost_dev_check_owner(d);
845 if (r)
846 goto done;
847
848 switch (ioctl) {
849 case VHOST_SET_MEM_TABLE:
850 r = vhost_set_memory(d, argp);
851 break;
852 case VHOST_SET_LOG_BASE:
853 if (copy_from_user(&p, argp, sizeof p)) {
854 r = -EFAULT;
855 break;
856 }
857 if ((u64)(unsigned long)p != p) {
858 r = -EFAULT;
859 break;
860 }
861 for (i = 0; i < d->nvqs; ++i) {
862 struct vhost_virtqueue *vq;
863 void __user *base = (void __user *)(unsigned long)p;
864 vq = d->vqs[i];
865 mutex_lock(&vq->mutex);
866 /* If ring is inactive, will check when it's enabled. */
867 if (vq->private_data && !vq_log_access_ok(vq, base))
868 r = -EFAULT;
869 else
870 vq->log_base = base;
871 mutex_unlock(&vq->mutex);
872 }
873 break;
874 case VHOST_SET_LOG_FD:
875 r = get_user(fd, (int __user *)argp);
876 if (r < 0)
877 break;
878 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
879 if (IS_ERR(eventfp)) {
880 r = PTR_ERR(eventfp);
881 break;
882 }
883 if (eventfp != d->log_file) {
884 filep = d->log_file;
885 ctx = d->log_ctx;
886 d->log_ctx = eventfp ?
887 eventfd_ctx_fileget(eventfp) : NULL;
888 } else
889 filep = eventfp;
890 for (i = 0; i < d->nvqs; ++i) {
891 mutex_lock(&d->vqs[i]->mutex);
892 d->vqs[i]->log_ctx = d->log_ctx;
893 mutex_unlock(&d->vqs[i]->mutex);
894 }
895 if (ctx)
896 eventfd_ctx_put(ctx);
897 if (filep)
898 fput(filep);
899 break;
900 default:
901 r = -ENOIOCTLCMD;
902 break;
903 }
904 done:
905 return r;
906 }
907 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
908
909 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
910 __u64 addr, __u32 len)
911 {
912 struct vhost_memory_region *reg;
913 int i;
914
915 /* linear search is not brilliant, but we really have on the order of 6
916 * regions in practice */
917 for (i = 0; i < mem->nregions; ++i) {
918 reg = mem->regions + i;
919 if (reg->guest_phys_addr <= addr &&
920 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
921 return reg;
922 }
923 return NULL;
924 }
925
926 /* TODO: This is really inefficient. We need something like get_user()
927 * (instruction directly accesses the data, with an exception table entry
928 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
929 */
930 static int set_bit_to_user(int nr, void __user *addr)
931 {
932 unsigned long log = (unsigned long)addr;
933 struct page *page;
934 void *base;
935 int bit = nr + (log % PAGE_SIZE) * 8;
936 int r;
937
938 r = get_user_pages_fast(log, 1, 1, &page);
939 if (r < 0)
940 return r;
941 BUG_ON(r != 1);
942 base = kmap_atomic(page);
943 set_bit(bit, base);
944 kunmap_atomic(base);
945 set_page_dirty_lock(page);
946 put_page(page);
947 return 0;
948 }
949
950 static int log_write(void __user *log_base,
951 u64 write_address, u64 write_length)
952 {
953 u64 write_page = write_address / VHOST_PAGE_SIZE;
954 int r;
955
956 if (!write_length)
957 return 0;
958 write_length += write_address % VHOST_PAGE_SIZE;
959 for (;;) {
960 u64 base = (u64)(unsigned long)log_base;
961 u64 log = base + write_page / 8;
962 int bit = write_page % 8;
963 if ((u64)(unsigned long)log != log)
964 return -EFAULT;
965 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
966 if (r < 0)
967 return r;
968 if (write_length <= VHOST_PAGE_SIZE)
969 break;
970 write_length -= VHOST_PAGE_SIZE;
971 write_page += 1;
972 }
973 return r;
974 }
975
976 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
977 unsigned int log_num, u64 len)
978 {
979 int i, r;
980
981 /* Make sure data written is seen before log. */
982 smp_wmb();
983 for (i = 0; i < log_num; ++i) {
984 u64 l = min(log[i].len, len);
985 r = log_write(vq->log_base, log[i].addr, l);
986 if (r < 0)
987 return r;
988 len -= l;
989 if (!len) {
990 if (vq->log_ctx)
991 eventfd_signal(vq->log_ctx, 1);
992 return 0;
993 }
994 }
995 /* Length written exceeds what we have stored. This is a bug. */
996 BUG();
997 return 0;
998 }
999 EXPORT_SYMBOL_GPL(vhost_log_write);
1000
1001 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1002 {
1003 void __user *used;
1004 if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0)
1005 return -EFAULT;
1006 if (unlikely(vq->log_used)) {
1007 /* Make sure the flag is seen before log. */
1008 smp_wmb();
1009 /* Log used flag write. */
1010 used = &vq->used->flags;
1011 log_write(vq->log_base, vq->log_addr +
1012 (used - (void __user *)vq->used),
1013 sizeof vq->used->flags);
1014 if (vq->log_ctx)
1015 eventfd_signal(vq->log_ctx, 1);
1016 }
1017 return 0;
1018 }
1019
1020 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1021 {
1022 if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq)))
1023 return -EFAULT;
1024 if (unlikely(vq->log_used)) {
1025 void __user *used;
1026 /* Make sure the event is seen before log. */
1027 smp_wmb();
1028 /* Log avail event write */
1029 used = vhost_avail_event(vq);
1030 log_write(vq->log_base, vq->log_addr +
1031 (used - (void __user *)vq->used),
1032 sizeof *vhost_avail_event(vq));
1033 if (vq->log_ctx)
1034 eventfd_signal(vq->log_ctx, 1);
1035 }
1036 return 0;
1037 }
1038
1039 int vhost_init_used(struct vhost_virtqueue *vq)
1040 {
1041 __virtio16 last_used_idx;
1042 int r;
1043 if (!vq->private_data)
1044 return 0;
1045
1046 r = vhost_update_used_flags(vq);
1047 if (r)
1048 return r;
1049 vq->signalled_used_valid = false;
1050 if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx))
1051 return -EFAULT;
1052 r = __get_user(last_used_idx, &vq->used->idx);
1053 if (r)
1054 return r;
1055 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1056 return 0;
1057 }
1058 EXPORT_SYMBOL_GPL(vhost_init_used);
1059
1060 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1061 struct iovec iov[], int iov_size)
1062 {
1063 const struct vhost_memory_region *reg;
1064 struct vhost_memory *mem;
1065 struct iovec *_iov;
1066 u64 s = 0;
1067 int ret = 0;
1068
1069 mem = vq->memory;
1070 while ((u64)len > s) {
1071 u64 size;
1072 if (unlikely(ret >= iov_size)) {
1073 ret = -ENOBUFS;
1074 break;
1075 }
1076 reg = find_region(mem, addr, len);
1077 if (unlikely(!reg)) {
1078 ret = -EFAULT;
1079 break;
1080 }
1081 _iov = iov + ret;
1082 size = reg->memory_size - addr + reg->guest_phys_addr;
1083 _iov->iov_len = min((u64)len - s, size);
1084 _iov->iov_base = (void __user *)(unsigned long)
1085 (reg->userspace_addr + addr - reg->guest_phys_addr);
1086 s += size;
1087 addr += size;
1088 ++ret;
1089 }
1090
1091 return ret;
1092 }
1093
1094 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1095 * function returns the next descriptor in the chain,
1096 * or -1U if we're at the end. */
1097 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1098 {
1099 unsigned int next;
1100
1101 /* If this descriptor says it doesn't chain, we're done. */
1102 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1103 return -1U;
1104
1105 /* Check they're not leading us off end of descriptors. */
1106 next = vhost16_to_cpu(vq, desc->next);
1107 /* Make sure compiler knows to grab that: we don't want it changing! */
1108 /* We will use the result as an index in an array, so most
1109 * architectures only need a compiler barrier here. */
1110 read_barrier_depends();
1111
1112 return next;
1113 }
1114
1115 static int get_indirect(struct vhost_virtqueue *vq,
1116 struct iovec iov[], unsigned int iov_size,
1117 unsigned int *out_num, unsigned int *in_num,
1118 struct vhost_log *log, unsigned int *log_num,
1119 struct vring_desc *indirect)
1120 {
1121 struct vring_desc desc;
1122 unsigned int i = 0, count, found = 0;
1123 u32 len = vhost32_to_cpu(vq, indirect->len);
1124 int ret;
1125
1126 /* Sanity check */
1127 if (unlikely(len % sizeof desc)) {
1128 vq_err(vq, "Invalid length in indirect descriptor: "
1129 "len 0x%llx not multiple of 0x%zx\n",
1130 (unsigned long long)len,
1131 sizeof desc);
1132 return -EINVAL;
1133 }
1134
1135 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1136 UIO_MAXIOV);
1137 if (unlikely(ret < 0)) {
1138 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1139 return ret;
1140 }
1141
1142 /* We will use the result as an address to read from, so most
1143 * architectures only need a compiler barrier here. */
1144 read_barrier_depends();
1145
1146 count = len / sizeof desc;
1147 /* Buffers are chained via a 16 bit next field, so
1148 * we can have at most 2^16 of these. */
1149 if (unlikely(count > USHRT_MAX + 1)) {
1150 vq_err(vq, "Indirect buffer length too big: %d\n",
1151 indirect->len);
1152 return -E2BIG;
1153 }
1154
1155 do {
1156 unsigned iov_count = *in_num + *out_num;
1157 if (unlikely(++found > count)) {
1158 vq_err(vq, "Loop detected: last one at %u "
1159 "indirect size %u\n",
1160 i, count);
1161 return -EINVAL;
1162 }
1163 if (unlikely(memcpy_fromiovec((unsigned char *)&desc,
1164 vq->indirect, sizeof desc))) {
1165 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1166 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1167 return -EINVAL;
1168 }
1169 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1170 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1171 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1172 return -EINVAL;
1173 }
1174
1175 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1176 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1177 iov_size - iov_count);
1178 if (unlikely(ret < 0)) {
1179 vq_err(vq, "Translation failure %d indirect idx %d\n",
1180 ret, i);
1181 return ret;
1182 }
1183 /* If this is an input descriptor, increment that count. */
1184 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
1185 *in_num += ret;
1186 if (unlikely(log)) {
1187 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1188 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1189 ++*log_num;
1190 }
1191 } else {
1192 /* If it's an output descriptor, they're all supposed
1193 * to come before any input descriptors. */
1194 if (unlikely(*in_num)) {
1195 vq_err(vq, "Indirect descriptor "
1196 "has out after in: idx %d\n", i);
1197 return -EINVAL;
1198 }
1199 *out_num += ret;
1200 }
1201 } while ((i = next_desc(vq, &desc)) != -1);
1202 return 0;
1203 }
1204
1205 /* This looks in the virtqueue and for the first available buffer, and converts
1206 * it to an iovec for convenient access. Since descriptors consist of some
1207 * number of output then some number of input descriptors, it's actually two
1208 * iovecs, but we pack them into one and note how many of each there were.
1209 *
1210 * This function returns the descriptor number found, or vq->num (which is
1211 * never a valid descriptor number) if none was found. A negative code is
1212 * returned on error. */
1213 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1214 struct iovec iov[], unsigned int iov_size,
1215 unsigned int *out_num, unsigned int *in_num,
1216 struct vhost_log *log, unsigned int *log_num)
1217 {
1218 struct vring_desc desc;
1219 unsigned int i, head, found = 0;
1220 u16 last_avail_idx;
1221 __virtio16 avail_idx;
1222 __virtio16 ring_head;
1223 int ret;
1224
1225 /* Check it isn't doing very strange things with descriptor numbers. */
1226 last_avail_idx = vq->last_avail_idx;
1227 if (unlikely(__get_user(avail_idx, &vq->avail->idx))) {
1228 vq_err(vq, "Failed to access avail idx at %p\n",
1229 &vq->avail->idx);
1230 return -EFAULT;
1231 }
1232 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1233
1234 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1235 vq_err(vq, "Guest moved used index from %u to %u",
1236 last_avail_idx, vq->avail_idx);
1237 return -EFAULT;
1238 }
1239
1240 /* If there's nothing new since last we looked, return invalid. */
1241 if (vq->avail_idx == last_avail_idx)
1242 return vq->num;
1243
1244 /* Only get avail ring entries after they have been exposed by guest. */
1245 smp_rmb();
1246
1247 /* Grab the next descriptor number they're advertising, and increment
1248 * the index we've seen. */
1249 if (unlikely(__get_user(ring_head,
1250 &vq->avail->ring[last_avail_idx % vq->num]))) {
1251 vq_err(vq, "Failed to read head: idx %d address %p\n",
1252 last_avail_idx,
1253 &vq->avail->ring[last_avail_idx % vq->num]);
1254 return -EFAULT;
1255 }
1256
1257 head = vhost16_to_cpu(vq, ring_head);
1258
1259 /* If their number is silly, that's an error. */
1260 if (unlikely(head >= vq->num)) {
1261 vq_err(vq, "Guest says index %u > %u is available",
1262 head, vq->num);
1263 return -EINVAL;
1264 }
1265
1266 /* When we start there are none of either input nor output. */
1267 *out_num = *in_num = 0;
1268 if (unlikely(log))
1269 *log_num = 0;
1270
1271 i = head;
1272 do {
1273 unsigned iov_count = *in_num + *out_num;
1274 if (unlikely(i >= vq->num)) {
1275 vq_err(vq, "Desc index is %u > %u, head = %u",
1276 i, vq->num, head);
1277 return -EINVAL;
1278 }
1279 if (unlikely(++found > vq->num)) {
1280 vq_err(vq, "Loop detected: last one at %u "
1281 "vq size %u head %u\n",
1282 i, vq->num, head);
1283 return -EINVAL;
1284 }
1285 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1286 if (unlikely(ret)) {
1287 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1288 i, vq->desc + i);
1289 return -EFAULT;
1290 }
1291 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
1292 ret = get_indirect(vq, iov, iov_size,
1293 out_num, in_num,
1294 log, log_num, &desc);
1295 if (unlikely(ret < 0)) {
1296 vq_err(vq, "Failure detected "
1297 "in indirect descriptor at idx %d\n", i);
1298 return ret;
1299 }
1300 continue;
1301 }
1302
1303 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1304 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1305 iov_size - iov_count);
1306 if (unlikely(ret < 0)) {
1307 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1308 ret, i);
1309 return ret;
1310 }
1311 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
1312 /* If this is an input descriptor,
1313 * increment that count. */
1314 *in_num += ret;
1315 if (unlikely(log)) {
1316 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1317 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1318 ++*log_num;
1319 }
1320 } else {
1321 /* If it's an output descriptor, they're all supposed
1322 * to come before any input descriptors. */
1323 if (unlikely(*in_num)) {
1324 vq_err(vq, "Descriptor has out after in: "
1325 "idx %d\n", i);
1326 return -EINVAL;
1327 }
1328 *out_num += ret;
1329 }
1330 } while ((i = next_desc(vq, &desc)) != -1);
1331
1332 /* On success, increment avail index. */
1333 vq->last_avail_idx++;
1334
1335 /* Assume notifications from guest are disabled at this point,
1336 * if they aren't we would need to update avail_event index. */
1337 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1338 return head;
1339 }
1340 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
1341
1342 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1343 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1344 {
1345 vq->last_avail_idx -= n;
1346 }
1347 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
1348
1349 /* After we've used one of their buffers, we tell them about it. We'll then
1350 * want to notify the guest, using eventfd. */
1351 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1352 {
1353 struct vring_used_elem heads = {
1354 cpu_to_vhost32(vq, head),
1355 cpu_to_vhost32(vq, len)
1356 };
1357
1358 return vhost_add_used_n(vq, &heads, 1);
1359 }
1360 EXPORT_SYMBOL_GPL(vhost_add_used);
1361
1362 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1363 struct vring_used_elem *heads,
1364 unsigned count)
1365 {
1366 struct vring_used_elem __user *used;
1367 u16 old, new;
1368 int start;
1369
1370 start = vq->last_used_idx % vq->num;
1371 used = vq->used->ring + start;
1372 if (count == 1) {
1373 if (__put_user(heads[0].id, &used->id)) {
1374 vq_err(vq, "Failed to write used id");
1375 return -EFAULT;
1376 }
1377 if (__put_user(heads[0].len, &used->len)) {
1378 vq_err(vq, "Failed to write used len");
1379 return -EFAULT;
1380 }
1381 } else if (__copy_to_user(used, heads, count * sizeof *used)) {
1382 vq_err(vq, "Failed to write used");
1383 return -EFAULT;
1384 }
1385 if (unlikely(vq->log_used)) {
1386 /* Make sure data is seen before log. */
1387 smp_wmb();
1388 /* Log used ring entry write. */
1389 log_write(vq->log_base,
1390 vq->log_addr +
1391 ((void __user *)used - (void __user *)vq->used),
1392 count * sizeof *used);
1393 }
1394 old = vq->last_used_idx;
1395 new = (vq->last_used_idx += count);
1396 /* If the driver never bothers to signal in a very long while,
1397 * used index might wrap around. If that happens, invalidate
1398 * signalled_used index we stored. TODO: make sure driver
1399 * signals at least once in 2^16 and remove this. */
1400 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1401 vq->signalled_used_valid = false;
1402 return 0;
1403 }
1404
1405 /* After we've used one of their buffers, we tell them about it. We'll then
1406 * want to notify the guest, using eventfd. */
1407 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1408 unsigned count)
1409 {
1410 int start, n, r;
1411
1412 start = vq->last_used_idx % vq->num;
1413 n = vq->num - start;
1414 if (n < count) {
1415 r = __vhost_add_used_n(vq, heads, n);
1416 if (r < 0)
1417 return r;
1418 heads += n;
1419 count -= n;
1420 }
1421 r = __vhost_add_used_n(vq, heads, count);
1422
1423 /* Make sure buffer is written before we update index. */
1424 smp_wmb();
1425 if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) {
1426 vq_err(vq, "Failed to increment used idx");
1427 return -EFAULT;
1428 }
1429 if (unlikely(vq->log_used)) {
1430 /* Log used index update. */
1431 log_write(vq->log_base,
1432 vq->log_addr + offsetof(struct vring_used, idx),
1433 sizeof vq->used->idx);
1434 if (vq->log_ctx)
1435 eventfd_signal(vq->log_ctx, 1);
1436 }
1437 return r;
1438 }
1439 EXPORT_SYMBOL_GPL(vhost_add_used_n);
1440
1441 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1442 {
1443 __u16 old, new;
1444 __virtio16 event;
1445 bool v;
1446 /* Flush out used index updates. This is paired
1447 * with the barrier that the Guest executes when enabling
1448 * interrupts. */
1449 smp_mb();
1450
1451 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1452 unlikely(vq->avail_idx == vq->last_avail_idx))
1453 return true;
1454
1455 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1456 __virtio16 flags;
1457 if (__get_user(flags, &vq->avail->flags)) {
1458 vq_err(vq, "Failed to get flags");
1459 return true;
1460 }
1461 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
1462 }
1463 old = vq->signalled_used;
1464 v = vq->signalled_used_valid;
1465 new = vq->signalled_used = vq->last_used_idx;
1466 vq->signalled_used_valid = true;
1467
1468 if (unlikely(!v))
1469 return true;
1470
1471 if (__get_user(event, vhost_used_event(vq))) {
1472 vq_err(vq, "Failed to get used event idx");
1473 return true;
1474 }
1475 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
1476 }
1477
1478 /* This actually signals the guest, using eventfd. */
1479 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1480 {
1481 /* Signal the Guest tell them we used something up. */
1482 if (vq->call_ctx && vhost_notify(dev, vq))
1483 eventfd_signal(vq->call_ctx, 1);
1484 }
1485 EXPORT_SYMBOL_GPL(vhost_signal);
1486
1487 /* And here's the combo meal deal. Supersize me! */
1488 void vhost_add_used_and_signal(struct vhost_dev *dev,
1489 struct vhost_virtqueue *vq,
1490 unsigned int head, int len)
1491 {
1492 vhost_add_used(vq, head, len);
1493 vhost_signal(dev, vq);
1494 }
1495 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
1496
1497 /* multi-buffer version of vhost_add_used_and_signal */
1498 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1499 struct vhost_virtqueue *vq,
1500 struct vring_used_elem *heads, unsigned count)
1501 {
1502 vhost_add_used_n(vq, heads, count);
1503 vhost_signal(dev, vq);
1504 }
1505 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
1506
1507 /* OK, now we need to know about added descriptors. */
1508 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1509 {
1510 __virtio16 avail_idx;
1511 int r;
1512
1513 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1514 return false;
1515 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1516 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1517 r = vhost_update_used_flags(vq);
1518 if (r) {
1519 vq_err(vq, "Failed to enable notification at %p: %d\n",
1520 &vq->used->flags, r);
1521 return false;
1522 }
1523 } else {
1524 r = vhost_update_avail_event(vq, vq->avail_idx);
1525 if (r) {
1526 vq_err(vq, "Failed to update avail event index at %p: %d\n",
1527 vhost_avail_event(vq), r);
1528 return false;
1529 }
1530 }
1531 /* They could have slipped one in as we were doing that: make
1532 * sure it's written, then check again. */
1533 smp_mb();
1534 r = __get_user(avail_idx, &vq->avail->idx);
1535 if (r) {
1536 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1537 &vq->avail->idx, r);
1538 return false;
1539 }
1540
1541 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
1542 }
1543 EXPORT_SYMBOL_GPL(vhost_enable_notify);
1544
1545 /* We don't need to be notified again. */
1546 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1547 {
1548 int r;
1549
1550 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1551 return;
1552 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1553 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1554 r = vhost_update_used_flags(vq);
1555 if (r)
1556 vq_err(vq, "Failed to enable notification at %p: %d\n",
1557 &vq->used->flags, r);
1558 }
1559 }
1560 EXPORT_SYMBOL_GPL(vhost_disable_notify);
1561
1562 static int __init vhost_init(void)
1563 {
1564 return 0;
1565 }
1566
1567 static void __exit vhost_exit(void)
1568 {
1569 }
1570
1571 module_init(vhost_init);
1572 module_exit(vhost_exit);
1573
1574 MODULE_VERSION("0.0.1");
1575 MODULE_LICENSE("GPL v2");
1576 MODULE_AUTHOR("Michael S. Tsirkin");
1577 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
Linux with added FPC-III support