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[mirror_ubuntu-zesty-kernel.git] / drivers / vhost / vhost.c
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/vmalloc.h>
26 #include <linux/kthread.h>
27 #include <linux/cgroup.h>
28 #include <linux/module.h>
29 #include <linux/sort.h>
30 #include <linux/interval_tree_generic.h>
31
32 #include "vhost.h"
33
34 static ushort max_mem_regions = 64;
35 module_param(max_mem_regions, ushort, 0444);
36 MODULE_PARM_DESC(max_mem_regions,
37 "Maximum number of memory regions in memory map. (default: 64)");
38 static int max_iotlb_entries = 2048;
39 module_param(max_iotlb_entries, int, 0444);
40 MODULE_PARM_DESC(max_iotlb_entries,
41 "Maximum number of iotlb entries. (default: 2048)");
42
43 enum {
44 VHOST_MEMORY_F_LOG = 0x1,
45 };
46
47 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
48 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
49
50 INTERVAL_TREE_DEFINE(struct vhost_umem_node,
51 rb, __u64, __subtree_last,
52 START, LAST, static inline, vhost_umem_interval_tree);
53
54 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
55 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
56 {
57 vq->user_be = !virtio_legacy_is_little_endian();
58 }
59
60 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
61 {
62 vq->user_be = true;
63 }
64
65 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
66 {
67 vq->user_be = false;
68 }
69
70 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
71 {
72 struct vhost_vring_state s;
73
74 if (vq->private_data)
75 return -EBUSY;
76
77 if (copy_from_user(&s, argp, sizeof(s)))
78 return -EFAULT;
79
80 if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
81 s.num != VHOST_VRING_BIG_ENDIAN)
82 return -EINVAL;
83
84 if (s.num == VHOST_VRING_BIG_ENDIAN)
85 vhost_enable_cross_endian_big(vq);
86 else
87 vhost_enable_cross_endian_little(vq);
88
89 return 0;
90 }
91
92 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
93 int __user *argp)
94 {
95 struct vhost_vring_state s = {
96 .index = idx,
97 .num = vq->user_be
98 };
99
100 if (copy_to_user(argp, &s, sizeof(s)))
101 return -EFAULT;
102
103 return 0;
104 }
105
106 static void vhost_init_is_le(struct vhost_virtqueue *vq)
107 {
108 /* Note for legacy virtio: user_be is initialized at reset time
109 * according to the host endianness. If userspace does not set an
110 * explicit endianness, the default behavior is native endian, as
111 * expected by legacy virtio.
112 */
113 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
114 }
115 #else
116 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
117 {
118 }
119
120 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
121 {
122 return -ENOIOCTLCMD;
123 }
124
125 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
126 int __user *argp)
127 {
128 return -ENOIOCTLCMD;
129 }
130
131 static void vhost_init_is_le(struct vhost_virtqueue *vq)
132 {
133 if (vhost_has_feature(vq, VIRTIO_F_VERSION_1))
134 vq->is_le = true;
135 }
136 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
137
138 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
139 {
140 vq->is_le = virtio_legacy_is_little_endian();
141 }
142
143 struct vhost_flush_struct {
144 struct vhost_work work;
145 struct completion wait_event;
146 };
147
148 static void vhost_flush_work(struct vhost_work *work)
149 {
150 struct vhost_flush_struct *s;
151
152 s = container_of(work, struct vhost_flush_struct, work);
153 complete(&s->wait_event);
154 }
155
156 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
157 poll_table *pt)
158 {
159 struct vhost_poll *poll;
160
161 poll = container_of(pt, struct vhost_poll, table);
162 poll->wqh = wqh;
163 add_wait_queue(wqh, &poll->wait);
164 }
165
166 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
167 void *key)
168 {
169 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
170
171 if (!((unsigned long)key & poll->mask))
172 return 0;
173
174 vhost_poll_queue(poll);
175 return 0;
176 }
177
178 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
179 {
180 clear_bit(VHOST_WORK_QUEUED, &work->flags);
181 work->fn = fn;
182 init_waitqueue_head(&work->done);
183 }
184 EXPORT_SYMBOL_GPL(vhost_work_init);
185
186 /* Init poll structure */
187 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
188 unsigned long mask, struct vhost_dev *dev)
189 {
190 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
191 init_poll_funcptr(&poll->table, vhost_poll_func);
192 poll->mask = mask;
193 poll->dev = dev;
194 poll->wqh = NULL;
195
196 vhost_work_init(&poll->work, fn);
197 }
198 EXPORT_SYMBOL_GPL(vhost_poll_init);
199
200 /* Start polling a file. We add ourselves to file's wait queue. The caller must
201 * keep a reference to a file until after vhost_poll_stop is called. */
202 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
203 {
204 unsigned long mask;
205 int ret = 0;
206
207 if (poll->wqh)
208 return 0;
209
210 mask = file->f_op->poll(file, &poll->table);
211 if (mask)
212 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
213 if (mask & POLLERR) {
214 if (poll->wqh)
215 remove_wait_queue(poll->wqh, &poll->wait);
216 ret = -EINVAL;
217 }
218
219 return ret;
220 }
221 EXPORT_SYMBOL_GPL(vhost_poll_start);
222
223 /* Stop polling a file. After this function returns, it becomes safe to drop the
224 * file reference. You must also flush afterwards. */
225 void vhost_poll_stop(struct vhost_poll *poll)
226 {
227 if (poll->wqh) {
228 remove_wait_queue(poll->wqh, &poll->wait);
229 poll->wqh = NULL;
230 }
231 }
232 EXPORT_SYMBOL_GPL(vhost_poll_stop);
233
234 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
235 {
236 struct vhost_flush_struct flush;
237
238 if (dev->worker) {
239 init_completion(&flush.wait_event);
240 vhost_work_init(&flush.work, vhost_flush_work);
241
242 vhost_work_queue(dev, &flush.work);
243 wait_for_completion(&flush.wait_event);
244 }
245 }
246 EXPORT_SYMBOL_GPL(vhost_work_flush);
247
248 /* Flush any work that has been scheduled. When calling this, don't hold any
249 * locks that are also used by the callback. */
250 void vhost_poll_flush(struct vhost_poll *poll)
251 {
252 vhost_work_flush(poll->dev, &poll->work);
253 }
254 EXPORT_SYMBOL_GPL(vhost_poll_flush);
255
256 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
257 {
258 if (!dev->worker)
259 return;
260
261 if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
262 /* We can only add the work to the list after we're
263 * sure it was not in the list.
264 * test_and_set_bit() implies a memory barrier.
265 */
266 llist_add(&work->node, &dev->work_list);
267 wake_up_process(dev->worker);
268 }
269 }
270 EXPORT_SYMBOL_GPL(vhost_work_queue);
271
272 /* A lockless hint for busy polling code to exit the loop */
273 bool vhost_has_work(struct vhost_dev *dev)
274 {
275 return !llist_empty(&dev->work_list);
276 }
277 EXPORT_SYMBOL_GPL(vhost_has_work);
278
279 void vhost_poll_queue(struct vhost_poll *poll)
280 {
281 vhost_work_queue(poll->dev, &poll->work);
282 }
283 EXPORT_SYMBOL_GPL(vhost_poll_queue);
284
285 static void vhost_vq_reset(struct vhost_dev *dev,
286 struct vhost_virtqueue *vq)
287 {
288 vq->num = 1;
289 vq->desc = NULL;
290 vq->avail = NULL;
291 vq->used = NULL;
292 vq->last_avail_idx = 0;
293 vq->avail_idx = 0;
294 vq->last_used_idx = 0;
295 vq->signalled_used = 0;
296 vq->signalled_used_valid = false;
297 vq->used_flags = 0;
298 vq->log_used = false;
299 vq->log_addr = -1ull;
300 vq->private_data = NULL;
301 vq->acked_features = 0;
302 vq->log_base = NULL;
303 vq->error_ctx = NULL;
304 vq->error = NULL;
305 vq->kick = NULL;
306 vq->call_ctx = NULL;
307 vq->call = NULL;
308 vq->log_ctx = NULL;
309 vhost_reset_is_le(vq);
310 vhost_disable_cross_endian(vq);
311 vq->busyloop_timeout = 0;
312 vq->umem = NULL;
313 vq->iotlb = NULL;
314 }
315
316 static int vhost_worker(void *data)
317 {
318 struct vhost_dev *dev = data;
319 struct vhost_work *work, *work_next;
320 struct llist_node *node;
321 mm_segment_t oldfs = get_fs();
322
323 set_fs(USER_DS);
324 use_mm(dev->mm);
325
326 for (;;) {
327 /* mb paired w/ kthread_stop */
328 set_current_state(TASK_INTERRUPTIBLE);
329
330 if (kthread_should_stop()) {
331 __set_current_state(TASK_RUNNING);
332 break;
333 }
334
335 node = llist_del_all(&dev->work_list);
336 if (!node)
337 schedule();
338
339 node = llist_reverse_order(node);
340 /* make sure flag is seen after deletion */
341 smp_wmb();
342 llist_for_each_entry_safe(work, work_next, node, node) {
343 clear_bit(VHOST_WORK_QUEUED, &work->flags);
344 __set_current_state(TASK_RUNNING);
345 work->fn(work);
346 if (need_resched())
347 schedule();
348 }
349 }
350 unuse_mm(dev->mm);
351 set_fs(oldfs);
352 return 0;
353 }
354
355 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
356 {
357 kfree(vq->indirect);
358 vq->indirect = NULL;
359 kfree(vq->log);
360 vq->log = NULL;
361 kfree(vq->heads);
362 vq->heads = NULL;
363 }
364
365 /* Helper to allocate iovec buffers for all vqs. */
366 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
367 {
368 struct vhost_virtqueue *vq;
369 int i;
370
371 for (i = 0; i < dev->nvqs; ++i) {
372 vq = dev->vqs[i];
373 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
374 GFP_KERNEL);
375 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
376 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
377 if (!vq->indirect || !vq->log || !vq->heads)
378 goto err_nomem;
379 }
380 return 0;
381
382 err_nomem:
383 for (; i >= 0; --i)
384 vhost_vq_free_iovecs(dev->vqs[i]);
385 return -ENOMEM;
386 }
387
388 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
389 {
390 int i;
391
392 for (i = 0; i < dev->nvqs; ++i)
393 vhost_vq_free_iovecs(dev->vqs[i]);
394 }
395
396 void vhost_dev_init(struct vhost_dev *dev,
397 struct vhost_virtqueue **vqs, int nvqs)
398 {
399 struct vhost_virtqueue *vq;
400 int i;
401
402 dev->vqs = vqs;
403 dev->nvqs = nvqs;
404 mutex_init(&dev->mutex);
405 dev->log_ctx = NULL;
406 dev->log_file = NULL;
407 dev->umem = NULL;
408 dev->iotlb = NULL;
409 dev->mm = NULL;
410 dev->worker = NULL;
411 init_llist_head(&dev->work_list);
412 init_waitqueue_head(&dev->wait);
413 INIT_LIST_HEAD(&dev->read_list);
414 INIT_LIST_HEAD(&dev->pending_list);
415 spin_lock_init(&dev->iotlb_lock);
416
417
418 for (i = 0; i < dev->nvqs; ++i) {
419 vq = dev->vqs[i];
420 vq->log = NULL;
421 vq->indirect = NULL;
422 vq->heads = NULL;
423 vq->dev = dev;
424 mutex_init(&vq->mutex);
425 vhost_vq_reset(dev, vq);
426 if (vq->handle_kick)
427 vhost_poll_init(&vq->poll, vq->handle_kick,
428 POLLIN, dev);
429 }
430 }
431 EXPORT_SYMBOL_GPL(vhost_dev_init);
432
433 /* Caller should have device mutex */
434 long vhost_dev_check_owner(struct vhost_dev *dev)
435 {
436 /* Are you the owner? If not, I don't think you mean to do that */
437 return dev->mm == current->mm ? 0 : -EPERM;
438 }
439 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
440
441 struct vhost_attach_cgroups_struct {
442 struct vhost_work work;
443 struct task_struct *owner;
444 int ret;
445 };
446
447 static void vhost_attach_cgroups_work(struct vhost_work *work)
448 {
449 struct vhost_attach_cgroups_struct *s;
450
451 s = container_of(work, struct vhost_attach_cgroups_struct, work);
452 s->ret = cgroup_attach_task_all(s->owner, current);
453 }
454
455 static int vhost_attach_cgroups(struct vhost_dev *dev)
456 {
457 struct vhost_attach_cgroups_struct attach;
458
459 attach.owner = current;
460 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
461 vhost_work_queue(dev, &attach.work);
462 vhost_work_flush(dev, &attach.work);
463 return attach.ret;
464 }
465
466 /* Caller should have device mutex */
467 bool vhost_dev_has_owner(struct vhost_dev *dev)
468 {
469 return dev->mm;
470 }
471 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
472
473 /* Caller should have device mutex */
474 long vhost_dev_set_owner(struct vhost_dev *dev)
475 {
476 struct task_struct *worker;
477 int err;
478
479 /* Is there an owner already? */
480 if (vhost_dev_has_owner(dev)) {
481 err = -EBUSY;
482 goto err_mm;
483 }
484
485 /* No owner, become one */
486 dev->mm = get_task_mm(current);
487 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
488 if (IS_ERR(worker)) {
489 err = PTR_ERR(worker);
490 goto err_worker;
491 }
492
493 dev->worker = worker;
494 wake_up_process(worker); /* avoid contributing to loadavg */
495
496 err = vhost_attach_cgroups(dev);
497 if (err)
498 goto err_cgroup;
499
500 err = vhost_dev_alloc_iovecs(dev);
501 if (err)
502 goto err_cgroup;
503
504 return 0;
505 err_cgroup:
506 kthread_stop(worker);
507 dev->worker = NULL;
508 err_worker:
509 if (dev->mm)
510 mmput(dev->mm);
511 dev->mm = NULL;
512 err_mm:
513 return err;
514 }
515 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
516
517 static void *vhost_kvzalloc(unsigned long size)
518 {
519 void *n = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
520
521 if (!n)
522 n = vzalloc(size);
523 return n;
524 }
525
526 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
527 {
528 return vhost_kvzalloc(sizeof(struct vhost_umem));
529 }
530 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
531
532 /* Caller should have device mutex */
533 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
534 {
535 int i;
536
537 vhost_dev_cleanup(dev, true);
538
539 /* Restore memory to default empty mapping. */
540 INIT_LIST_HEAD(&umem->umem_list);
541 dev->umem = umem;
542 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
543 * VQs aren't running.
544 */
545 for (i = 0; i < dev->nvqs; ++i)
546 dev->vqs[i]->umem = umem;
547 }
548 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
549
550 void vhost_dev_stop(struct vhost_dev *dev)
551 {
552 int i;
553
554 for (i = 0; i < dev->nvqs; ++i) {
555 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
556 vhost_poll_stop(&dev->vqs[i]->poll);
557 vhost_poll_flush(&dev->vqs[i]->poll);
558 }
559 }
560 }
561 EXPORT_SYMBOL_GPL(vhost_dev_stop);
562
563 static void vhost_umem_free(struct vhost_umem *umem,
564 struct vhost_umem_node *node)
565 {
566 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
567 list_del(&node->link);
568 kfree(node);
569 umem->numem--;
570 }
571
572 static void vhost_umem_clean(struct vhost_umem *umem)
573 {
574 struct vhost_umem_node *node, *tmp;
575
576 if (!umem)
577 return;
578
579 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
580 vhost_umem_free(umem, node);
581
582 kvfree(umem);
583 }
584
585 static void vhost_clear_msg(struct vhost_dev *dev)
586 {
587 struct vhost_msg_node *node, *n;
588
589 spin_lock(&dev->iotlb_lock);
590
591 list_for_each_entry_safe(node, n, &dev->read_list, node) {
592 list_del(&node->node);
593 kfree(node);
594 }
595
596 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
597 list_del(&node->node);
598 kfree(node);
599 }
600
601 spin_unlock(&dev->iotlb_lock);
602 }
603
604 /* Caller should have device mutex if and only if locked is set */
605 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
606 {
607 int i;
608
609 for (i = 0; i < dev->nvqs; ++i) {
610 if (dev->vqs[i]->error_ctx)
611 eventfd_ctx_put(dev->vqs[i]->error_ctx);
612 if (dev->vqs[i]->error)
613 fput(dev->vqs[i]->error);
614 if (dev->vqs[i]->kick)
615 fput(dev->vqs[i]->kick);
616 if (dev->vqs[i]->call_ctx)
617 eventfd_ctx_put(dev->vqs[i]->call_ctx);
618 if (dev->vqs[i]->call)
619 fput(dev->vqs[i]->call);
620 vhost_vq_reset(dev, dev->vqs[i]);
621 }
622 vhost_dev_free_iovecs(dev);
623 if (dev->log_ctx)
624 eventfd_ctx_put(dev->log_ctx);
625 dev->log_ctx = NULL;
626 if (dev->log_file)
627 fput(dev->log_file);
628 dev->log_file = NULL;
629 /* No one will access memory at this point */
630 vhost_umem_clean(dev->umem);
631 dev->umem = NULL;
632 vhost_umem_clean(dev->iotlb);
633 dev->iotlb = NULL;
634 vhost_clear_msg(dev);
635 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
636 WARN_ON(!llist_empty(&dev->work_list));
637 if (dev->worker) {
638 kthread_stop(dev->worker);
639 dev->worker = NULL;
640 }
641 if (dev->mm)
642 mmput(dev->mm);
643 dev->mm = NULL;
644 }
645 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
646
647 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
648 {
649 u64 a = addr / VHOST_PAGE_SIZE / 8;
650
651 /* Make sure 64 bit math will not overflow. */
652 if (a > ULONG_MAX - (unsigned long)log_base ||
653 a + (unsigned long)log_base > ULONG_MAX)
654 return 0;
655
656 return access_ok(VERIFY_WRITE, log_base + a,
657 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
658 }
659
660 static bool vhost_overflow(u64 uaddr, u64 size)
661 {
662 /* Make sure 64 bit math will not overflow. */
663 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
664 }
665
666 /* Caller should have vq mutex and device mutex. */
667 static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
668 int log_all)
669 {
670 struct vhost_umem_node *node;
671
672 if (!umem)
673 return 0;
674
675 list_for_each_entry(node, &umem->umem_list, link) {
676 unsigned long a = node->userspace_addr;
677
678 if (vhost_overflow(node->userspace_addr, node->size))
679 return 0;
680
681
682 if (!access_ok(VERIFY_WRITE, (void __user *)a,
683 node->size))
684 return 0;
685 else if (log_all && !log_access_ok(log_base,
686 node->start,
687 node->size))
688 return 0;
689 }
690 return 1;
691 }
692
693 /* Can we switch to this memory table? */
694 /* Caller should have device mutex but not vq mutex */
695 static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
696 int log_all)
697 {
698 int i;
699
700 for (i = 0; i < d->nvqs; ++i) {
701 int ok;
702 bool log;
703
704 mutex_lock(&d->vqs[i]->mutex);
705 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
706 /* If ring is inactive, will check when it's enabled. */
707 if (d->vqs[i]->private_data)
708 ok = vq_memory_access_ok(d->vqs[i]->log_base,
709 umem, log);
710 else
711 ok = 1;
712 mutex_unlock(&d->vqs[i]->mutex);
713 if (!ok)
714 return 0;
715 }
716 return 1;
717 }
718
719 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
720 struct iovec iov[], int iov_size, int access);
721
722 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
723 const void *from, unsigned size)
724 {
725 int ret;
726
727 if (!vq->iotlb)
728 return __copy_to_user(to, from, size);
729 else {
730 /* This function should be called after iotlb
731 * prefetch, which means we're sure that all vq
732 * could be access through iotlb. So -EAGAIN should
733 * not happen in this case.
734 */
735 /* TODO: more fast path */
736 struct iov_iter t;
737 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
738 ARRAY_SIZE(vq->iotlb_iov),
739 VHOST_ACCESS_WO);
740 if (ret < 0)
741 goto out;
742 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
743 ret = copy_to_iter(from, size, &t);
744 if (ret == size)
745 ret = 0;
746 }
747 out:
748 return ret;
749 }
750
751 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
752 void __user *from, unsigned size)
753 {
754 int ret;
755
756 if (!vq->iotlb)
757 return __copy_from_user(to, from, size);
758 else {
759 /* This function should be called after iotlb
760 * prefetch, which means we're sure that vq
761 * could be access through iotlb. So -EAGAIN should
762 * not happen in this case.
763 */
764 /* TODO: more fast path */
765 struct iov_iter f;
766 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
767 ARRAY_SIZE(vq->iotlb_iov),
768 VHOST_ACCESS_RO);
769 if (ret < 0) {
770 vq_err(vq, "IOTLB translation failure: uaddr "
771 "%p size 0x%llx\n", from,
772 (unsigned long long) size);
773 goto out;
774 }
775 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
776 ret = copy_from_iter(to, size, &f);
777 if (ret == size)
778 ret = 0;
779 }
780
781 out:
782 return ret;
783 }
784
785 static void __user *__vhost_get_user(struct vhost_virtqueue *vq,
786 void __user *addr, unsigned size)
787 {
788 int ret;
789
790 /* This function should be called after iotlb
791 * prefetch, which means we're sure that vq
792 * could be access through iotlb. So -EAGAIN should
793 * not happen in this case.
794 */
795 /* TODO: more fast path */
796 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
797 ARRAY_SIZE(vq->iotlb_iov),
798 VHOST_ACCESS_RO);
799 if (ret < 0) {
800 vq_err(vq, "IOTLB translation failure: uaddr "
801 "%p size 0x%llx\n", addr,
802 (unsigned long long) size);
803 return NULL;
804 }
805
806 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
807 vq_err(vq, "Non atomic userspace memory access: uaddr "
808 "%p size 0x%llx\n", addr,
809 (unsigned long long) size);
810 return NULL;
811 }
812
813 return vq->iotlb_iov[0].iov_base;
814 }
815
816 #define vhost_put_user(vq, x, ptr) \
817 ({ \
818 int ret = -EFAULT; \
819 if (!vq->iotlb) { \
820 ret = __put_user(x, ptr); \
821 } else { \
822 __typeof__(ptr) to = \
823 (__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
824 if (to != NULL) \
825 ret = __put_user(x, to); \
826 else \
827 ret = -EFAULT; \
828 } \
829 ret; \
830 })
831
832 #define vhost_get_user(vq, x, ptr) \
833 ({ \
834 int ret; \
835 if (!vq->iotlb) { \
836 ret = __get_user(x, ptr); \
837 } else { \
838 __typeof__(ptr) from = \
839 (__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
840 if (from != NULL) \
841 ret = __get_user(x, from); \
842 else \
843 ret = -EFAULT; \
844 } \
845 ret; \
846 })
847
848 static void vhost_dev_lock_vqs(struct vhost_dev *d)
849 {
850 int i = 0;
851 for (i = 0; i < d->nvqs; ++i)
852 mutex_lock(&d->vqs[i]->mutex);
853 }
854
855 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
856 {
857 int i = 0;
858 for (i = 0; i < d->nvqs; ++i)
859 mutex_unlock(&d->vqs[i]->mutex);
860 }
861
862 static int vhost_new_umem_range(struct vhost_umem *umem,
863 u64 start, u64 size, u64 end,
864 u64 userspace_addr, int perm)
865 {
866 struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
867
868 if (!node)
869 return -ENOMEM;
870
871 if (umem->numem == max_iotlb_entries) {
872 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
873 vhost_umem_free(umem, tmp);
874 }
875
876 node->start = start;
877 node->size = size;
878 node->last = end;
879 node->userspace_addr = userspace_addr;
880 node->perm = perm;
881 INIT_LIST_HEAD(&node->link);
882 list_add_tail(&node->link, &umem->umem_list);
883 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
884 umem->numem++;
885
886 return 0;
887 }
888
889 static void vhost_del_umem_range(struct vhost_umem *umem,
890 u64 start, u64 end)
891 {
892 struct vhost_umem_node *node;
893
894 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
895 start, end)))
896 vhost_umem_free(umem, node);
897 }
898
899 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
900 struct vhost_iotlb_msg *msg)
901 {
902 struct vhost_msg_node *node, *n;
903
904 spin_lock(&d->iotlb_lock);
905
906 list_for_each_entry_safe(node, n, &d->pending_list, node) {
907 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
908 if (msg->iova <= vq_msg->iova &&
909 msg->iova + msg->size - 1 > vq_msg->iova &&
910 vq_msg->type == VHOST_IOTLB_MISS) {
911 vhost_poll_queue(&node->vq->poll);
912 list_del(&node->node);
913 kfree(node);
914 }
915 }
916
917 spin_unlock(&d->iotlb_lock);
918 }
919
920 static int umem_access_ok(u64 uaddr, u64 size, int access)
921 {
922 unsigned long a = uaddr;
923
924 /* Make sure 64 bit math will not overflow. */
925 if (vhost_overflow(uaddr, size))
926 return -EFAULT;
927
928 if ((access & VHOST_ACCESS_RO) &&
929 !access_ok(VERIFY_READ, (void __user *)a, size))
930 return -EFAULT;
931 if ((access & VHOST_ACCESS_WO) &&
932 !access_ok(VERIFY_WRITE, (void __user *)a, size))
933 return -EFAULT;
934 return 0;
935 }
936
937 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
938 struct vhost_iotlb_msg *msg)
939 {
940 int ret = 0;
941
942 vhost_dev_lock_vqs(dev);
943 switch (msg->type) {
944 case VHOST_IOTLB_UPDATE:
945 if (!dev->iotlb) {
946 ret = -EFAULT;
947 break;
948 }
949 if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
950 ret = -EFAULT;
951 break;
952 }
953 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
954 msg->iova + msg->size - 1,
955 msg->uaddr, msg->perm)) {
956 ret = -ENOMEM;
957 break;
958 }
959 vhost_iotlb_notify_vq(dev, msg);
960 break;
961 case VHOST_IOTLB_INVALIDATE:
962 vhost_del_umem_range(dev->iotlb, msg->iova,
963 msg->iova + msg->size - 1);
964 break;
965 default:
966 ret = -EINVAL;
967 break;
968 }
969
970 vhost_dev_unlock_vqs(dev);
971 return ret;
972 }
973 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
974 struct iov_iter *from)
975 {
976 struct vhost_msg_node node;
977 unsigned size = sizeof(struct vhost_msg);
978 size_t ret;
979 int err;
980
981 if (iov_iter_count(from) < size)
982 return 0;
983 ret = copy_from_iter(&node.msg, size, from);
984 if (ret != size)
985 goto done;
986
987 switch (node.msg.type) {
988 case VHOST_IOTLB_MSG:
989 err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
990 if (err)
991 ret = err;
992 break;
993 default:
994 ret = -EINVAL;
995 break;
996 }
997
998 done:
999 return ret;
1000 }
1001 EXPORT_SYMBOL(vhost_chr_write_iter);
1002
1003 unsigned int vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1004 poll_table *wait)
1005 {
1006 unsigned int mask = 0;
1007
1008 poll_wait(file, &dev->wait, wait);
1009
1010 if (!list_empty(&dev->read_list))
1011 mask |= POLLIN | POLLRDNORM;
1012
1013 return mask;
1014 }
1015 EXPORT_SYMBOL(vhost_chr_poll);
1016
1017 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1018 int noblock)
1019 {
1020 DEFINE_WAIT(wait);
1021 struct vhost_msg_node *node;
1022 ssize_t ret = 0;
1023 unsigned size = sizeof(struct vhost_msg);
1024
1025 if (iov_iter_count(to) < size)
1026 return 0;
1027
1028 while (1) {
1029 if (!noblock)
1030 prepare_to_wait(&dev->wait, &wait,
1031 TASK_INTERRUPTIBLE);
1032
1033 node = vhost_dequeue_msg(dev, &dev->read_list);
1034 if (node)
1035 break;
1036 if (noblock) {
1037 ret = -EAGAIN;
1038 break;
1039 }
1040 if (signal_pending(current)) {
1041 ret = -ERESTARTSYS;
1042 break;
1043 }
1044 if (!dev->iotlb) {
1045 ret = -EBADFD;
1046 break;
1047 }
1048
1049 schedule();
1050 }
1051
1052 if (!noblock)
1053 finish_wait(&dev->wait, &wait);
1054
1055 if (node) {
1056 ret = copy_to_iter(&node->msg, size, to);
1057
1058 if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {
1059 kfree(node);
1060 return ret;
1061 }
1062
1063 vhost_enqueue_msg(dev, &dev->pending_list, node);
1064 }
1065
1066 return ret;
1067 }
1068 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1069
1070 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1071 {
1072 struct vhost_dev *dev = vq->dev;
1073 struct vhost_msg_node *node;
1074 struct vhost_iotlb_msg *msg;
1075
1076 node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
1077 if (!node)
1078 return -ENOMEM;
1079
1080 msg = &node->msg.iotlb;
1081 msg->type = VHOST_IOTLB_MISS;
1082 msg->iova = iova;
1083 msg->perm = access;
1084
1085 vhost_enqueue_msg(dev, &dev->read_list, node);
1086
1087 return 0;
1088 }
1089
1090 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1091 struct vring_desc __user *desc,
1092 struct vring_avail __user *avail,
1093 struct vring_used __user *used)
1094
1095 {
1096 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1097
1098 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
1099 access_ok(VERIFY_READ, avail,
1100 sizeof *avail + num * sizeof *avail->ring + s) &&
1101 access_ok(VERIFY_WRITE, used,
1102 sizeof *used + num * sizeof *used->ring + s);
1103 }
1104
1105 static int iotlb_access_ok(struct vhost_virtqueue *vq,
1106 int access, u64 addr, u64 len)
1107 {
1108 const struct vhost_umem_node *node;
1109 struct vhost_umem *umem = vq->iotlb;
1110 u64 s = 0, size;
1111
1112 while (len > s) {
1113 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1114 addr,
1115 addr + len - 1);
1116 if (node == NULL || node->start > addr) {
1117 vhost_iotlb_miss(vq, addr, access);
1118 return false;
1119 } else if (!(node->perm & access)) {
1120 /* Report the possible access violation by
1121 * request another translation from userspace.
1122 */
1123 return false;
1124 }
1125
1126 size = node->size - addr + node->start;
1127 s += size;
1128 addr += size;
1129 }
1130
1131 return true;
1132 }
1133
1134 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1135 {
1136 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1137 unsigned int num = vq->num;
1138
1139 if (!vq->iotlb)
1140 return 1;
1141
1142 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1143 num * sizeof *vq->desc) &&
1144 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1145 sizeof *vq->avail +
1146 num * sizeof *vq->avail->ring + s) &&
1147 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1148 sizeof *vq->used +
1149 num * sizeof *vq->used->ring + s);
1150 }
1151 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1152
1153 /* Can we log writes? */
1154 /* Caller should have device mutex but not vq mutex */
1155 int vhost_log_access_ok(struct vhost_dev *dev)
1156 {
1157 return memory_access_ok(dev, dev->umem, 1);
1158 }
1159 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1160
1161 /* Verify access for write logging. */
1162 /* Caller should have vq mutex and device mutex */
1163 static int vq_log_access_ok(struct vhost_virtqueue *vq,
1164 void __user *log_base)
1165 {
1166 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1167
1168 return vq_memory_access_ok(log_base, vq->umem,
1169 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1170 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1171 sizeof *vq->used +
1172 vq->num * sizeof *vq->used->ring + s));
1173 }
1174
1175 /* Can we start vq? */
1176 /* Caller should have vq mutex and device mutex */
1177 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
1178 {
1179 if (vq->iotlb) {
1180 /* When device IOTLB was used, the access validation
1181 * will be validated during prefetching.
1182 */
1183 return 1;
1184 }
1185 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
1186 vq_log_access_ok(vq, vq->log_base);
1187 }
1188 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1189
1190 static struct vhost_umem *vhost_umem_alloc(void)
1191 {
1192 struct vhost_umem *umem = vhost_kvzalloc(sizeof(*umem));
1193
1194 if (!umem)
1195 return NULL;
1196
1197 umem->umem_tree = RB_ROOT;
1198 umem->numem = 0;
1199 INIT_LIST_HEAD(&umem->umem_list);
1200
1201 return umem;
1202 }
1203
1204 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1205 {
1206 struct vhost_memory mem, *newmem;
1207 struct vhost_memory_region *region;
1208 struct vhost_umem *newumem, *oldumem;
1209 unsigned long size = offsetof(struct vhost_memory, regions);
1210 int i;
1211
1212 if (copy_from_user(&mem, m, size))
1213 return -EFAULT;
1214 if (mem.padding)
1215 return -EOPNOTSUPP;
1216 if (mem.nregions > max_mem_regions)
1217 return -E2BIG;
1218 newmem = vhost_kvzalloc(size + mem.nregions * sizeof(*m->regions));
1219 if (!newmem)
1220 return -ENOMEM;
1221
1222 memcpy(newmem, &mem, size);
1223 if (copy_from_user(newmem->regions, m->regions,
1224 mem.nregions * sizeof *m->regions)) {
1225 kvfree(newmem);
1226 return -EFAULT;
1227 }
1228
1229 newumem = vhost_umem_alloc();
1230 if (!newumem) {
1231 kvfree(newmem);
1232 return -ENOMEM;
1233 }
1234
1235 for (region = newmem->regions;
1236 region < newmem->regions + mem.nregions;
1237 region++) {
1238 if (vhost_new_umem_range(newumem,
1239 region->guest_phys_addr,
1240 region->memory_size,
1241 region->guest_phys_addr +
1242 region->memory_size - 1,
1243 region->userspace_addr,
1244 VHOST_ACCESS_RW))
1245 goto err;
1246 }
1247
1248 if (!memory_access_ok(d, newumem, 0))
1249 goto err;
1250
1251 oldumem = d->umem;
1252 d->umem = newumem;
1253
1254 /* All memory accesses are done under some VQ mutex. */
1255 for (i = 0; i < d->nvqs; ++i) {
1256 mutex_lock(&d->vqs[i]->mutex);
1257 d->vqs[i]->umem = newumem;
1258 mutex_unlock(&d->vqs[i]->mutex);
1259 }
1260
1261 kvfree(newmem);
1262 vhost_umem_clean(oldumem);
1263 return 0;
1264
1265 err:
1266 vhost_umem_clean(newumem);
1267 kvfree(newmem);
1268 return -EFAULT;
1269 }
1270
1271 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
1272 {
1273 struct file *eventfp, *filep = NULL;
1274 bool pollstart = false, pollstop = false;
1275 struct eventfd_ctx *ctx = NULL;
1276 u32 __user *idxp = argp;
1277 struct vhost_virtqueue *vq;
1278 struct vhost_vring_state s;
1279 struct vhost_vring_file f;
1280 struct vhost_vring_addr a;
1281 u32 idx;
1282 long r;
1283
1284 r = get_user(idx, idxp);
1285 if (r < 0)
1286 return r;
1287 if (idx >= d->nvqs)
1288 return -ENOBUFS;
1289
1290 vq = d->vqs[idx];
1291
1292 mutex_lock(&vq->mutex);
1293
1294 switch (ioctl) {
1295 case VHOST_SET_VRING_NUM:
1296 /* Resizing ring with an active backend?
1297 * You don't want to do that. */
1298 if (vq->private_data) {
1299 r = -EBUSY;
1300 break;
1301 }
1302 if (copy_from_user(&s, argp, sizeof s)) {
1303 r = -EFAULT;
1304 break;
1305 }
1306 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1307 r = -EINVAL;
1308 break;
1309 }
1310 vq->num = s.num;
1311 break;
1312 case VHOST_SET_VRING_BASE:
1313 /* Moving base with an active backend?
1314 * You don't want to do that. */
1315 if (vq->private_data) {
1316 r = -EBUSY;
1317 break;
1318 }
1319 if (copy_from_user(&s, argp, sizeof s)) {
1320 r = -EFAULT;
1321 break;
1322 }
1323 if (s.num > 0xffff) {
1324 r = -EINVAL;
1325 break;
1326 }
1327 vq->last_avail_idx = s.num;
1328 /* Forget the cached index value. */
1329 vq->avail_idx = vq->last_avail_idx;
1330 break;
1331 case VHOST_GET_VRING_BASE:
1332 s.index = idx;
1333 s.num = vq->last_avail_idx;
1334 if (copy_to_user(argp, &s, sizeof s))
1335 r = -EFAULT;
1336 break;
1337 case VHOST_SET_VRING_ADDR:
1338 if (copy_from_user(&a, argp, sizeof a)) {
1339 r = -EFAULT;
1340 break;
1341 }
1342 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1343 r = -EOPNOTSUPP;
1344 break;
1345 }
1346 /* For 32bit, verify that the top 32bits of the user
1347 data are set to zero. */
1348 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1349 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1350 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1351 r = -EFAULT;
1352 break;
1353 }
1354
1355 /* Make sure it's safe to cast pointers to vring types. */
1356 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1357 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1358 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1359 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1360 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1361 r = -EINVAL;
1362 break;
1363 }
1364
1365 /* We only verify access here if backend is configured.
1366 * If it is not, we don't as size might not have been setup.
1367 * We will verify when backend is configured. */
1368 if (vq->private_data) {
1369 if (!vq_access_ok(vq, vq->num,
1370 (void __user *)(unsigned long)a.desc_user_addr,
1371 (void __user *)(unsigned long)a.avail_user_addr,
1372 (void __user *)(unsigned long)a.used_user_addr)) {
1373 r = -EINVAL;
1374 break;
1375 }
1376
1377 /* Also validate log access for used ring if enabled. */
1378 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1379 !log_access_ok(vq->log_base, a.log_guest_addr,
1380 sizeof *vq->used +
1381 vq->num * sizeof *vq->used->ring)) {
1382 r = -EINVAL;
1383 break;
1384 }
1385 }
1386
1387 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1388 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1389 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1390 vq->log_addr = a.log_guest_addr;
1391 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1392 break;
1393 case VHOST_SET_VRING_KICK:
1394 if (copy_from_user(&f, argp, sizeof f)) {
1395 r = -EFAULT;
1396 break;
1397 }
1398 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1399 if (IS_ERR(eventfp)) {
1400 r = PTR_ERR(eventfp);
1401 break;
1402 }
1403 if (eventfp != vq->kick) {
1404 pollstop = (filep = vq->kick) != NULL;
1405 pollstart = (vq->kick = eventfp) != NULL;
1406 } else
1407 filep = eventfp;
1408 break;
1409 case VHOST_SET_VRING_CALL:
1410 if (copy_from_user(&f, argp, sizeof f)) {
1411 r = -EFAULT;
1412 break;
1413 }
1414 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1415 if (IS_ERR(eventfp)) {
1416 r = PTR_ERR(eventfp);
1417 break;
1418 }
1419 if (eventfp != vq->call) {
1420 filep = vq->call;
1421 ctx = vq->call_ctx;
1422 vq->call = eventfp;
1423 vq->call_ctx = eventfp ?
1424 eventfd_ctx_fileget(eventfp) : NULL;
1425 } else
1426 filep = eventfp;
1427 break;
1428 case VHOST_SET_VRING_ERR:
1429 if (copy_from_user(&f, argp, sizeof f)) {
1430 r = -EFAULT;
1431 break;
1432 }
1433 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1434 if (IS_ERR(eventfp)) {
1435 r = PTR_ERR(eventfp);
1436 break;
1437 }
1438 if (eventfp != vq->error) {
1439 filep = vq->error;
1440 vq->error = eventfp;
1441 ctx = vq->error_ctx;
1442 vq->error_ctx = eventfp ?
1443 eventfd_ctx_fileget(eventfp) : NULL;
1444 } else
1445 filep = eventfp;
1446 break;
1447 case VHOST_SET_VRING_ENDIAN:
1448 r = vhost_set_vring_endian(vq, argp);
1449 break;
1450 case VHOST_GET_VRING_ENDIAN:
1451 r = vhost_get_vring_endian(vq, idx, argp);
1452 break;
1453 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1454 if (copy_from_user(&s, argp, sizeof(s))) {
1455 r = -EFAULT;
1456 break;
1457 }
1458 vq->busyloop_timeout = s.num;
1459 break;
1460 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1461 s.index = idx;
1462 s.num = vq->busyloop_timeout;
1463 if (copy_to_user(argp, &s, sizeof(s)))
1464 r = -EFAULT;
1465 break;
1466 default:
1467 r = -ENOIOCTLCMD;
1468 }
1469
1470 if (pollstop && vq->handle_kick)
1471 vhost_poll_stop(&vq->poll);
1472
1473 if (ctx)
1474 eventfd_ctx_put(ctx);
1475 if (filep)
1476 fput(filep);
1477
1478 if (pollstart && vq->handle_kick)
1479 r = vhost_poll_start(&vq->poll, vq->kick);
1480
1481 mutex_unlock(&vq->mutex);
1482
1483 if (pollstop && vq->handle_kick)
1484 vhost_poll_flush(&vq->poll);
1485 return r;
1486 }
1487 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1488
1489 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1490 {
1491 struct vhost_umem *niotlb, *oiotlb;
1492 int i;
1493
1494 niotlb = vhost_umem_alloc();
1495 if (!niotlb)
1496 return -ENOMEM;
1497
1498 oiotlb = d->iotlb;
1499 d->iotlb = niotlb;
1500
1501 for (i = 0; i < d->nvqs; ++i) {
1502 mutex_lock(&d->vqs[i]->mutex);
1503 d->vqs[i]->iotlb = niotlb;
1504 mutex_unlock(&d->vqs[i]->mutex);
1505 }
1506
1507 vhost_umem_clean(oiotlb);
1508
1509 return 0;
1510 }
1511 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1512
1513 /* Caller must have device mutex */
1514 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1515 {
1516 struct file *eventfp, *filep = NULL;
1517 struct eventfd_ctx *ctx = NULL;
1518 u64 p;
1519 long r;
1520 int i, fd;
1521
1522 /* If you are not the owner, you can become one */
1523 if (ioctl == VHOST_SET_OWNER) {
1524 r = vhost_dev_set_owner(d);
1525 goto done;
1526 }
1527
1528 /* You must be the owner to do anything else */
1529 r = vhost_dev_check_owner(d);
1530 if (r)
1531 goto done;
1532
1533 switch (ioctl) {
1534 case VHOST_SET_MEM_TABLE:
1535 r = vhost_set_memory(d, argp);
1536 break;
1537 case VHOST_SET_LOG_BASE:
1538 if (copy_from_user(&p, argp, sizeof p)) {
1539 r = -EFAULT;
1540 break;
1541 }
1542 if ((u64)(unsigned long)p != p) {
1543 r = -EFAULT;
1544 break;
1545 }
1546 for (i = 0; i < d->nvqs; ++i) {
1547 struct vhost_virtqueue *vq;
1548 void __user *base = (void __user *)(unsigned long)p;
1549 vq = d->vqs[i];
1550 mutex_lock(&vq->mutex);
1551 /* If ring is inactive, will check when it's enabled. */
1552 if (vq->private_data && !vq_log_access_ok(vq, base))
1553 r = -EFAULT;
1554 else
1555 vq->log_base = base;
1556 mutex_unlock(&vq->mutex);
1557 }
1558 break;
1559 case VHOST_SET_LOG_FD:
1560 r = get_user(fd, (int __user *)argp);
1561 if (r < 0)
1562 break;
1563 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
1564 if (IS_ERR(eventfp)) {
1565 r = PTR_ERR(eventfp);
1566 break;
1567 }
1568 if (eventfp != d->log_file) {
1569 filep = d->log_file;
1570 d->log_file = eventfp;
1571 ctx = d->log_ctx;
1572 d->log_ctx = eventfp ?
1573 eventfd_ctx_fileget(eventfp) : NULL;
1574 } else
1575 filep = eventfp;
1576 for (i = 0; i < d->nvqs; ++i) {
1577 mutex_lock(&d->vqs[i]->mutex);
1578 d->vqs[i]->log_ctx = d->log_ctx;
1579 mutex_unlock(&d->vqs[i]->mutex);
1580 }
1581 if (ctx)
1582 eventfd_ctx_put(ctx);
1583 if (filep)
1584 fput(filep);
1585 break;
1586 default:
1587 r = -ENOIOCTLCMD;
1588 break;
1589 }
1590 done:
1591 return r;
1592 }
1593 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1594
1595 /* TODO: This is really inefficient. We need something like get_user()
1596 * (instruction directly accesses the data, with an exception table entry
1597 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1598 */
1599 static int set_bit_to_user(int nr, void __user *addr)
1600 {
1601 unsigned long log = (unsigned long)addr;
1602 struct page *page;
1603 void *base;
1604 int bit = nr + (log % PAGE_SIZE) * 8;
1605 int r;
1606
1607 r = get_user_pages_fast(log, 1, 1, &page);
1608 if (r < 0)
1609 return r;
1610 BUG_ON(r != 1);
1611 base = kmap_atomic(page);
1612 set_bit(bit, base);
1613 kunmap_atomic(base);
1614 set_page_dirty_lock(page);
1615 put_page(page);
1616 return 0;
1617 }
1618
1619 static int log_write(void __user *log_base,
1620 u64 write_address, u64 write_length)
1621 {
1622 u64 write_page = write_address / VHOST_PAGE_SIZE;
1623 int r;
1624
1625 if (!write_length)
1626 return 0;
1627 write_length += write_address % VHOST_PAGE_SIZE;
1628 for (;;) {
1629 u64 base = (u64)(unsigned long)log_base;
1630 u64 log = base + write_page / 8;
1631 int bit = write_page % 8;
1632 if ((u64)(unsigned long)log != log)
1633 return -EFAULT;
1634 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1635 if (r < 0)
1636 return r;
1637 if (write_length <= VHOST_PAGE_SIZE)
1638 break;
1639 write_length -= VHOST_PAGE_SIZE;
1640 write_page += 1;
1641 }
1642 return r;
1643 }
1644
1645 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1646 unsigned int log_num, u64 len)
1647 {
1648 int i, r;
1649
1650 /* Make sure data written is seen before log. */
1651 smp_wmb();
1652 for (i = 0; i < log_num; ++i) {
1653 u64 l = min(log[i].len, len);
1654 r = log_write(vq->log_base, log[i].addr, l);
1655 if (r < 0)
1656 return r;
1657 len -= l;
1658 if (!len) {
1659 if (vq->log_ctx)
1660 eventfd_signal(vq->log_ctx, 1);
1661 return 0;
1662 }
1663 }
1664 /* Length written exceeds what we have stored. This is a bug. */
1665 BUG();
1666 return 0;
1667 }
1668 EXPORT_SYMBOL_GPL(vhost_log_write);
1669
1670 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1671 {
1672 void __user *used;
1673 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1674 &vq->used->flags) < 0)
1675 return -EFAULT;
1676 if (unlikely(vq->log_used)) {
1677 /* Make sure the flag is seen before log. */
1678 smp_wmb();
1679 /* Log used flag write. */
1680 used = &vq->used->flags;
1681 log_write(vq->log_base, vq->log_addr +
1682 (used - (void __user *)vq->used),
1683 sizeof vq->used->flags);
1684 if (vq->log_ctx)
1685 eventfd_signal(vq->log_ctx, 1);
1686 }
1687 return 0;
1688 }
1689
1690 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1691 {
1692 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1693 vhost_avail_event(vq)))
1694 return -EFAULT;
1695 if (unlikely(vq->log_used)) {
1696 void __user *used;
1697 /* Make sure the event is seen before log. */
1698 smp_wmb();
1699 /* Log avail event write */
1700 used = vhost_avail_event(vq);
1701 log_write(vq->log_base, vq->log_addr +
1702 (used - (void __user *)vq->used),
1703 sizeof *vhost_avail_event(vq));
1704 if (vq->log_ctx)
1705 eventfd_signal(vq->log_ctx, 1);
1706 }
1707 return 0;
1708 }
1709
1710 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1711 {
1712 __virtio16 last_used_idx;
1713 int r;
1714 bool is_le = vq->is_le;
1715
1716 if (!vq->private_data) {
1717 vhost_reset_is_le(vq);
1718 return 0;
1719 }
1720
1721 vhost_init_is_le(vq);
1722
1723 r = vhost_update_used_flags(vq);
1724 if (r)
1725 goto err;
1726 vq->signalled_used_valid = false;
1727 if (!vq->iotlb &&
1728 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1729 r = -EFAULT;
1730 goto err;
1731 }
1732 r = vhost_get_user(vq, last_used_idx, &vq->used->idx);
1733 if (r) {
1734 vq_err(vq, "Can't access used idx at %p\n",
1735 &vq->used->idx);
1736 goto err;
1737 }
1738 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1739 return 0;
1740
1741 err:
1742 vq->is_le = is_le;
1743 return r;
1744 }
1745 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1746
1747 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1748 struct iovec iov[], int iov_size, int access)
1749 {
1750 const struct vhost_umem_node *node;
1751 struct vhost_dev *dev = vq->dev;
1752 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1753 struct iovec *_iov;
1754 u64 s = 0;
1755 int ret = 0;
1756
1757 while ((u64)len > s) {
1758 u64 size;
1759 if (unlikely(ret >= iov_size)) {
1760 ret = -ENOBUFS;
1761 break;
1762 }
1763
1764 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1765 addr, addr + len - 1);
1766 if (node == NULL || node->start > addr) {
1767 if (umem != dev->iotlb) {
1768 ret = -EFAULT;
1769 break;
1770 }
1771 ret = -EAGAIN;
1772 break;
1773 } else if (!(node->perm & access)) {
1774 ret = -EPERM;
1775 break;
1776 }
1777
1778 _iov = iov + ret;
1779 size = node->size - addr + node->start;
1780 _iov->iov_len = min((u64)len - s, size);
1781 _iov->iov_base = (void __user *)(unsigned long)
1782 (node->userspace_addr + addr - node->start);
1783 s += size;
1784 addr += size;
1785 ++ret;
1786 }
1787
1788 if (ret == -EAGAIN)
1789 vhost_iotlb_miss(vq, addr, access);
1790 return ret;
1791 }
1792
1793 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1794 * function returns the next descriptor in the chain,
1795 * or -1U if we're at the end. */
1796 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1797 {
1798 unsigned int next;
1799
1800 /* If this descriptor says it doesn't chain, we're done. */
1801 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1802 return -1U;
1803
1804 /* Check they're not leading us off end of descriptors. */
1805 next = vhost16_to_cpu(vq, desc->next);
1806 /* Make sure compiler knows to grab that: we don't want it changing! */
1807 /* We will use the result as an index in an array, so most
1808 * architectures only need a compiler barrier here. */
1809 read_barrier_depends();
1810
1811 return next;
1812 }
1813
1814 static int get_indirect(struct vhost_virtqueue *vq,
1815 struct iovec iov[], unsigned int iov_size,
1816 unsigned int *out_num, unsigned int *in_num,
1817 struct vhost_log *log, unsigned int *log_num,
1818 struct vring_desc *indirect)
1819 {
1820 struct vring_desc desc;
1821 unsigned int i = 0, count, found = 0;
1822 u32 len = vhost32_to_cpu(vq, indirect->len);
1823 struct iov_iter from;
1824 int ret, access;
1825
1826 /* Sanity check */
1827 if (unlikely(len % sizeof desc)) {
1828 vq_err(vq, "Invalid length in indirect descriptor: "
1829 "len 0x%llx not multiple of 0x%zx\n",
1830 (unsigned long long)len,
1831 sizeof desc);
1832 return -EINVAL;
1833 }
1834
1835 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1836 UIO_MAXIOV, VHOST_ACCESS_RO);
1837 if (unlikely(ret < 0)) {
1838 if (ret != -EAGAIN)
1839 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1840 return ret;
1841 }
1842 iov_iter_init(&from, READ, vq->indirect, ret, len);
1843
1844 /* We will use the result as an address to read from, so most
1845 * architectures only need a compiler barrier here. */
1846 read_barrier_depends();
1847
1848 count = len / sizeof desc;
1849 /* Buffers are chained via a 16 bit next field, so
1850 * we can have at most 2^16 of these. */
1851 if (unlikely(count > USHRT_MAX + 1)) {
1852 vq_err(vq, "Indirect buffer length too big: %d\n",
1853 indirect->len);
1854 return -E2BIG;
1855 }
1856
1857 do {
1858 unsigned iov_count = *in_num + *out_num;
1859 if (unlikely(++found > count)) {
1860 vq_err(vq, "Loop detected: last one at %u "
1861 "indirect size %u\n",
1862 i, count);
1863 return -EINVAL;
1864 }
1865 if (unlikely(copy_from_iter(&desc, sizeof(desc), &from) !=
1866 sizeof(desc))) {
1867 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1868 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1869 return -EINVAL;
1870 }
1871 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1872 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1873 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1874 return -EINVAL;
1875 }
1876
1877 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1878 access = VHOST_ACCESS_WO;
1879 else
1880 access = VHOST_ACCESS_RO;
1881
1882 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1883 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1884 iov_size - iov_count, access);
1885 if (unlikely(ret < 0)) {
1886 if (ret != -EAGAIN)
1887 vq_err(vq, "Translation failure %d indirect idx %d\n",
1888 ret, i);
1889 return ret;
1890 }
1891 /* If this is an input descriptor, increment that count. */
1892 if (access == VHOST_ACCESS_WO) {
1893 *in_num += ret;
1894 if (unlikely(log)) {
1895 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1896 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1897 ++*log_num;
1898 }
1899 } else {
1900 /* If it's an output descriptor, they're all supposed
1901 * to come before any input descriptors. */
1902 if (unlikely(*in_num)) {
1903 vq_err(vq, "Indirect descriptor "
1904 "has out after in: idx %d\n", i);
1905 return -EINVAL;
1906 }
1907 *out_num += ret;
1908 }
1909 } while ((i = next_desc(vq, &desc)) != -1);
1910 return 0;
1911 }
1912
1913 /* This looks in the virtqueue and for the first available buffer, and converts
1914 * it to an iovec for convenient access. Since descriptors consist of some
1915 * number of output then some number of input descriptors, it's actually two
1916 * iovecs, but we pack them into one and note how many of each there were.
1917 *
1918 * This function returns the descriptor number found, or vq->num (which is
1919 * never a valid descriptor number) if none was found. A negative code is
1920 * returned on error. */
1921 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1922 struct iovec iov[], unsigned int iov_size,
1923 unsigned int *out_num, unsigned int *in_num,
1924 struct vhost_log *log, unsigned int *log_num)
1925 {
1926 struct vring_desc desc;
1927 unsigned int i, head, found = 0;
1928 u16 last_avail_idx;
1929 __virtio16 avail_idx;
1930 __virtio16 ring_head;
1931 int ret, access;
1932
1933 /* Check it isn't doing very strange things with descriptor numbers. */
1934 last_avail_idx = vq->last_avail_idx;
1935 if (unlikely(vhost_get_user(vq, avail_idx, &vq->avail->idx))) {
1936 vq_err(vq, "Failed to access avail idx at %p\n",
1937 &vq->avail->idx);
1938 return -EFAULT;
1939 }
1940 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1941
1942 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1943 vq_err(vq, "Guest moved used index from %u to %u",
1944 last_avail_idx, vq->avail_idx);
1945 return -EFAULT;
1946 }
1947
1948 /* If there's nothing new since last we looked, return invalid. */
1949 if (vq->avail_idx == last_avail_idx)
1950 return vq->num;
1951
1952 /* Only get avail ring entries after they have been exposed by guest. */
1953 smp_rmb();
1954
1955 /* Grab the next descriptor number they're advertising, and increment
1956 * the index we've seen. */
1957 if (unlikely(vhost_get_user(vq, ring_head,
1958 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
1959 vq_err(vq, "Failed to read head: idx %d address %p\n",
1960 last_avail_idx,
1961 &vq->avail->ring[last_avail_idx % vq->num]);
1962 return -EFAULT;
1963 }
1964
1965 head = vhost16_to_cpu(vq, ring_head);
1966
1967 /* If their number is silly, that's an error. */
1968 if (unlikely(head >= vq->num)) {
1969 vq_err(vq, "Guest says index %u > %u is available",
1970 head, vq->num);
1971 return -EINVAL;
1972 }
1973
1974 /* When we start there are none of either input nor output. */
1975 *out_num = *in_num = 0;
1976 if (unlikely(log))
1977 *log_num = 0;
1978
1979 i = head;
1980 do {
1981 unsigned iov_count = *in_num + *out_num;
1982 if (unlikely(i >= vq->num)) {
1983 vq_err(vq, "Desc index is %u > %u, head = %u",
1984 i, vq->num, head);
1985 return -EINVAL;
1986 }
1987 if (unlikely(++found > vq->num)) {
1988 vq_err(vq, "Loop detected: last one at %u "
1989 "vq size %u head %u\n",
1990 i, vq->num, head);
1991 return -EINVAL;
1992 }
1993 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
1994 sizeof desc);
1995 if (unlikely(ret)) {
1996 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1997 i, vq->desc + i);
1998 return -EFAULT;
1999 }
2000 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2001 ret = get_indirect(vq, iov, iov_size,
2002 out_num, in_num,
2003 log, log_num, &desc);
2004 if (unlikely(ret < 0)) {
2005 if (ret != -EAGAIN)
2006 vq_err(vq, "Failure detected "
2007 "in indirect descriptor at idx %d\n", i);
2008 return ret;
2009 }
2010 continue;
2011 }
2012
2013 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2014 access = VHOST_ACCESS_WO;
2015 else
2016 access = VHOST_ACCESS_RO;
2017 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2018 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2019 iov_size - iov_count, access);
2020 if (unlikely(ret < 0)) {
2021 if (ret != -EAGAIN)
2022 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2023 ret, i);
2024 return ret;
2025 }
2026 if (access == VHOST_ACCESS_WO) {
2027 /* If this is an input descriptor,
2028 * increment that count. */
2029 *in_num += ret;
2030 if (unlikely(log)) {
2031 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2032 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2033 ++*log_num;
2034 }
2035 } else {
2036 /* If it's an output descriptor, they're all supposed
2037 * to come before any input descriptors. */
2038 if (unlikely(*in_num)) {
2039 vq_err(vq, "Descriptor has out after in: "
2040 "idx %d\n", i);
2041 return -EINVAL;
2042 }
2043 *out_num += ret;
2044 }
2045 } while ((i = next_desc(vq, &desc)) != -1);
2046
2047 /* On success, increment avail index. */
2048 vq->last_avail_idx++;
2049
2050 /* Assume notifications from guest are disabled at this point,
2051 * if they aren't we would need to update avail_event index. */
2052 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2053 return head;
2054 }
2055 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2056
2057 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2058 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2059 {
2060 vq->last_avail_idx -= n;
2061 }
2062 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2063
2064 /* After we've used one of their buffers, we tell them about it. We'll then
2065 * want to notify the guest, using eventfd. */
2066 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2067 {
2068 struct vring_used_elem heads = {
2069 cpu_to_vhost32(vq, head),
2070 cpu_to_vhost32(vq, len)
2071 };
2072
2073 return vhost_add_used_n(vq, &heads, 1);
2074 }
2075 EXPORT_SYMBOL_GPL(vhost_add_used);
2076
2077 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2078 struct vring_used_elem *heads,
2079 unsigned count)
2080 {
2081 struct vring_used_elem __user *used;
2082 u16 old, new;
2083 int start;
2084
2085 start = vq->last_used_idx & (vq->num - 1);
2086 used = vq->used->ring + start;
2087 if (count == 1) {
2088 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2089 vq_err(vq, "Failed to write used id");
2090 return -EFAULT;
2091 }
2092 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2093 vq_err(vq, "Failed to write used len");
2094 return -EFAULT;
2095 }
2096 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2097 vq_err(vq, "Failed to write used");
2098 return -EFAULT;
2099 }
2100 if (unlikely(vq->log_used)) {
2101 /* Make sure data is seen before log. */
2102 smp_wmb();
2103 /* Log used ring entry write. */
2104 log_write(vq->log_base,
2105 vq->log_addr +
2106 ((void __user *)used - (void __user *)vq->used),
2107 count * sizeof *used);
2108 }
2109 old = vq->last_used_idx;
2110 new = (vq->last_used_idx += count);
2111 /* If the driver never bothers to signal in a very long while,
2112 * used index might wrap around. If that happens, invalidate
2113 * signalled_used index we stored. TODO: make sure driver
2114 * signals at least once in 2^16 and remove this. */
2115 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2116 vq->signalled_used_valid = false;
2117 return 0;
2118 }
2119
2120 /* After we've used one of their buffers, we tell them about it. We'll then
2121 * want to notify the guest, using eventfd. */
2122 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2123 unsigned count)
2124 {
2125 int start, n, r;
2126
2127 start = vq->last_used_idx & (vq->num - 1);
2128 n = vq->num - start;
2129 if (n < count) {
2130 r = __vhost_add_used_n(vq, heads, n);
2131 if (r < 0)
2132 return r;
2133 heads += n;
2134 count -= n;
2135 }
2136 r = __vhost_add_used_n(vq, heads, count);
2137
2138 /* Make sure buffer is written before we update index. */
2139 smp_wmb();
2140 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2141 &vq->used->idx)) {
2142 vq_err(vq, "Failed to increment used idx");
2143 return -EFAULT;
2144 }
2145 if (unlikely(vq->log_used)) {
2146 /* Log used index update. */
2147 log_write(vq->log_base,
2148 vq->log_addr + offsetof(struct vring_used, idx),
2149 sizeof vq->used->idx);
2150 if (vq->log_ctx)
2151 eventfd_signal(vq->log_ctx, 1);
2152 }
2153 return r;
2154 }
2155 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2156
2157 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2158 {
2159 __u16 old, new;
2160 __virtio16 event;
2161 bool v;
2162 /* Flush out used index updates. This is paired
2163 * with the barrier that the Guest executes when enabling
2164 * interrupts. */
2165 smp_mb();
2166
2167 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2168 unlikely(vq->avail_idx == vq->last_avail_idx))
2169 return true;
2170
2171 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2172 __virtio16 flags;
2173 if (vhost_get_user(vq, flags, &vq->avail->flags)) {
2174 vq_err(vq, "Failed to get flags");
2175 return true;
2176 }
2177 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2178 }
2179 old = vq->signalled_used;
2180 v = vq->signalled_used_valid;
2181 new = vq->signalled_used = vq->last_used_idx;
2182 vq->signalled_used_valid = true;
2183
2184 if (unlikely(!v))
2185 return true;
2186
2187 if (vhost_get_user(vq, event, vhost_used_event(vq))) {
2188 vq_err(vq, "Failed to get used event idx");
2189 return true;
2190 }
2191 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2192 }
2193
2194 /* This actually signals the guest, using eventfd. */
2195 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2196 {
2197 /* Signal the Guest tell them we used something up. */
2198 if (vq->call_ctx && vhost_notify(dev, vq))
2199 eventfd_signal(vq->call_ctx, 1);
2200 }
2201 EXPORT_SYMBOL_GPL(vhost_signal);
2202
2203 /* And here's the combo meal deal. Supersize me! */
2204 void vhost_add_used_and_signal(struct vhost_dev *dev,
2205 struct vhost_virtqueue *vq,
2206 unsigned int head, int len)
2207 {
2208 vhost_add_used(vq, head, len);
2209 vhost_signal(dev, vq);
2210 }
2211 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2212
2213 /* multi-buffer version of vhost_add_used_and_signal */
2214 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2215 struct vhost_virtqueue *vq,
2216 struct vring_used_elem *heads, unsigned count)
2217 {
2218 vhost_add_used_n(vq, heads, count);
2219 vhost_signal(dev, vq);
2220 }
2221 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2222
2223 /* return true if we're sure that avaiable ring is empty */
2224 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2225 {
2226 __virtio16 avail_idx;
2227 int r;
2228
2229 r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
2230 if (r)
2231 return false;
2232
2233 return vhost16_to_cpu(vq, avail_idx) == vq->avail_idx;
2234 }
2235 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2236
2237 /* OK, now we need to know about added descriptors. */
2238 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2239 {
2240 __virtio16 avail_idx;
2241 int r;
2242
2243 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2244 return false;
2245 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2246 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2247 r = vhost_update_used_flags(vq);
2248 if (r) {
2249 vq_err(vq, "Failed to enable notification at %p: %d\n",
2250 &vq->used->flags, r);
2251 return false;
2252 }
2253 } else {
2254 r = vhost_update_avail_event(vq, vq->avail_idx);
2255 if (r) {
2256 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2257 vhost_avail_event(vq), r);
2258 return false;
2259 }
2260 }
2261 /* They could have slipped one in as we were doing that: make
2262 * sure it's written, then check again. */
2263 smp_mb();
2264 r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
2265 if (r) {
2266 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2267 &vq->avail->idx, r);
2268 return false;
2269 }
2270
2271 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2272 }
2273 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2274
2275 /* We don't need to be notified again. */
2276 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2277 {
2278 int r;
2279
2280 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2281 return;
2282 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2283 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2284 r = vhost_update_used_flags(vq);
2285 if (r)
2286 vq_err(vq, "Failed to enable notification at %p: %d\n",
2287 &vq->used->flags, r);
2288 }
2289 }
2290 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2291
2292 /* Create a new message. */
2293 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2294 {
2295 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2296 if (!node)
2297 return NULL;
2298 node->vq = vq;
2299 node->msg.type = type;
2300 return node;
2301 }
2302 EXPORT_SYMBOL_GPL(vhost_new_msg);
2303
2304 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2305 struct vhost_msg_node *node)
2306 {
2307 spin_lock(&dev->iotlb_lock);
2308 list_add_tail(&node->node, head);
2309 spin_unlock(&dev->iotlb_lock);
2310
2311 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
2312 }
2313 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2314
2315 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2316 struct list_head *head)
2317 {
2318 struct vhost_msg_node *node = NULL;
2319
2320 spin_lock(&dev->iotlb_lock);
2321 if (!list_empty(head)) {
2322 node = list_first_entry(head, struct vhost_msg_node,
2323 node);
2324 list_del(&node->node);
2325 }
2326 spin_unlock(&dev->iotlb_lock);
2327
2328 return node;
2329 }
2330 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2331
2332
2333 static int __init vhost_init(void)
2334 {
2335 return 0;
2336 }
2337
2338 static void __exit vhost_exit(void)
2339 {
2340 }
2341
2342 module_init(vhost_init);
2343 module_exit(vhost_exit);
2344
2345 MODULE_VERSION("0.0.1");
2346 MODULE_LICENSE("GPL v2");
2347 MODULE_AUTHOR("Michael S. Tsirkin");
2348 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
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