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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 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
134 || virtio_legacy_is_little_endian();
135 }
136 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
137
138 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
139 {
140 vhost_init_is_le(vq);
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->last_used_event = 0;
294 vq->avail_idx = 0;
295 vq->last_used_idx = 0;
296 vq->signalled_used = 0;
297 vq->signalled_used_valid = false;
298 vq->used_flags = 0;
299 vq->log_used = false;
300 vq->log_addr = -1ull;
301 vq->private_data = NULL;
302 vq->acked_features = 0;
303 vq->log_base = NULL;
304 vq->error_ctx = NULL;
305 vq->error = NULL;
306 vq->kick = NULL;
307 vq->call_ctx = NULL;
308 vq->call = NULL;
309 vq->log_ctx = NULL;
310 vhost_reset_is_le(vq);
311 vhost_disable_cross_endian(vq);
312 vq->busyloop_timeout = 0;
313 vq->umem = NULL;
314 vq->iotlb = NULL;
315 }
316
317 static int vhost_worker(void *data)
318 {
319 struct vhost_dev *dev = data;
320 struct vhost_work *work, *work_next;
321 struct llist_node *node;
322 mm_segment_t oldfs = get_fs();
323
324 set_fs(USER_DS);
325 use_mm(dev->mm);
326
327 for (;;) {
328 /* mb paired w/ kthread_stop */
329 set_current_state(TASK_INTERRUPTIBLE);
330
331 if (kthread_should_stop()) {
332 __set_current_state(TASK_RUNNING);
333 break;
334 }
335
336 node = llist_del_all(&dev->work_list);
337 if (!node)
338 schedule();
339
340 node = llist_reverse_order(node);
341 /* make sure flag is seen after deletion */
342 smp_wmb();
343 llist_for_each_entry_safe(work, work_next, node, node) {
344 clear_bit(VHOST_WORK_QUEUED, &work->flags);
345 __set_current_state(TASK_RUNNING);
346 work->fn(work);
347 if (need_resched())
348 schedule();
349 }
350 }
351 unuse_mm(dev->mm);
352 set_fs(oldfs);
353 return 0;
354 }
355
356 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
357 {
358 kfree(vq->indirect);
359 vq->indirect = NULL;
360 kfree(vq->log);
361 vq->log = NULL;
362 kfree(vq->heads);
363 vq->heads = NULL;
364 }
365
366 /* Helper to allocate iovec buffers for all vqs. */
367 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
368 {
369 struct vhost_virtqueue *vq;
370 int i;
371
372 for (i = 0; i < dev->nvqs; ++i) {
373 vq = dev->vqs[i];
374 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
375 GFP_KERNEL);
376 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
377 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
378 if (!vq->indirect || !vq->log || !vq->heads)
379 goto err_nomem;
380 }
381 return 0;
382
383 err_nomem:
384 for (; i >= 0; --i)
385 vhost_vq_free_iovecs(dev->vqs[i]);
386 return -ENOMEM;
387 }
388
389 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
390 {
391 int i;
392
393 for (i = 0; i < dev->nvqs; ++i)
394 vhost_vq_free_iovecs(dev->vqs[i]);
395 }
396
397 void vhost_dev_init(struct vhost_dev *dev,
398 struct vhost_virtqueue **vqs, int nvqs)
399 {
400 struct vhost_virtqueue *vq;
401 int i;
402
403 dev->vqs = vqs;
404 dev->nvqs = nvqs;
405 mutex_init(&dev->mutex);
406 dev->log_ctx = NULL;
407 dev->log_file = NULL;
408 dev->umem = NULL;
409 dev->iotlb = NULL;
410 dev->mm = NULL;
411 dev->worker = NULL;
412 init_llist_head(&dev->work_list);
413 init_waitqueue_head(&dev->wait);
414 INIT_LIST_HEAD(&dev->read_list);
415 INIT_LIST_HEAD(&dev->pending_list);
416 spin_lock_init(&dev->iotlb_lock);
417
418
419 for (i = 0; i < dev->nvqs; ++i) {
420 vq = dev->vqs[i];
421 vq->log = NULL;
422 vq->indirect = NULL;
423 vq->heads = NULL;
424 vq->dev = dev;
425 mutex_init(&vq->mutex);
426 vhost_vq_reset(dev, vq);
427 if (vq->handle_kick)
428 vhost_poll_init(&vq->poll, vq->handle_kick,
429 POLLIN, dev);
430 }
431 }
432 EXPORT_SYMBOL_GPL(vhost_dev_init);
433
434 /* Caller should have device mutex */
435 long vhost_dev_check_owner(struct vhost_dev *dev)
436 {
437 /* Are you the owner? If not, I don't think you mean to do that */
438 return dev->mm == current->mm ? 0 : -EPERM;
439 }
440 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
441
442 struct vhost_attach_cgroups_struct {
443 struct vhost_work work;
444 struct task_struct *owner;
445 int ret;
446 };
447
448 static void vhost_attach_cgroups_work(struct vhost_work *work)
449 {
450 struct vhost_attach_cgroups_struct *s;
451
452 s = container_of(work, struct vhost_attach_cgroups_struct, work);
453 s->ret = cgroup_attach_task_all(s->owner, current);
454 }
455
456 static int vhost_attach_cgroups(struct vhost_dev *dev)
457 {
458 struct vhost_attach_cgroups_struct attach;
459
460 attach.owner = current;
461 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
462 vhost_work_queue(dev, &attach.work);
463 vhost_work_flush(dev, &attach.work);
464 return attach.ret;
465 }
466
467 /* Caller should have device mutex */
468 bool vhost_dev_has_owner(struct vhost_dev *dev)
469 {
470 return dev->mm;
471 }
472 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
473
474 /* Caller should have device mutex */
475 long vhost_dev_set_owner(struct vhost_dev *dev)
476 {
477 struct task_struct *worker;
478 int err;
479
480 /* Is there an owner already? */
481 if (vhost_dev_has_owner(dev)) {
482 err = -EBUSY;
483 goto err_mm;
484 }
485
486 /* No owner, become one */
487 dev->mm = get_task_mm(current);
488 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
489 if (IS_ERR(worker)) {
490 err = PTR_ERR(worker);
491 goto err_worker;
492 }
493
494 dev->worker = worker;
495 wake_up_process(worker); /* avoid contributing to loadavg */
496
497 err = vhost_attach_cgroups(dev);
498 if (err)
499 goto err_cgroup;
500
501 err = vhost_dev_alloc_iovecs(dev);
502 if (err)
503 goto err_cgroup;
504
505 return 0;
506 err_cgroup:
507 kthread_stop(worker);
508 dev->worker = NULL;
509 err_worker:
510 if (dev->mm)
511 mmput(dev->mm);
512 dev->mm = NULL;
513 err_mm:
514 return err;
515 }
516 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
517
518 static void *vhost_kvzalloc(unsigned long size)
519 {
520 void *n = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
521
522 if (!n)
523 n = vzalloc(size);
524 return n;
525 }
526
527 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
528 {
529 return vhost_kvzalloc(sizeof(struct vhost_umem));
530 }
531 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
532
533 /* Caller should have device mutex */
534 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
535 {
536 int i;
537
538 vhost_dev_cleanup(dev, true);
539
540 /* Restore memory to default empty mapping. */
541 INIT_LIST_HEAD(&umem->umem_list);
542 dev->umem = umem;
543 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
544 * VQs aren't running.
545 */
546 for (i = 0; i < dev->nvqs; ++i)
547 dev->vqs[i]->umem = umem;
548 }
549 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
550
551 void vhost_dev_stop(struct vhost_dev *dev)
552 {
553 int i;
554
555 for (i = 0; i < dev->nvqs; ++i) {
556 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
557 vhost_poll_stop(&dev->vqs[i]->poll);
558 vhost_poll_flush(&dev->vqs[i]->poll);
559 }
560 }
561 }
562 EXPORT_SYMBOL_GPL(vhost_dev_stop);
563
564 static void vhost_umem_free(struct vhost_umem *umem,
565 struct vhost_umem_node *node)
566 {
567 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
568 list_del(&node->link);
569 kfree(node);
570 umem->numem--;
571 }
572
573 static void vhost_umem_clean(struct vhost_umem *umem)
574 {
575 struct vhost_umem_node *node, *tmp;
576
577 if (!umem)
578 return;
579
580 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
581 vhost_umem_free(umem, node);
582
583 kvfree(umem);
584 }
585
586 static void vhost_clear_msg(struct vhost_dev *dev)
587 {
588 struct vhost_msg_node *node, *n;
589
590 spin_lock(&dev->iotlb_lock);
591
592 list_for_each_entry_safe(node, n, &dev->read_list, node) {
593 list_del(&node->node);
594 kfree(node);
595 }
596
597 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
598 list_del(&node->node);
599 kfree(node);
600 }
601
602 spin_unlock(&dev->iotlb_lock);
603 }
604
605 /* Caller should have device mutex if and only if locked is set */
606 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
607 {
608 int i;
609
610 for (i = 0; i < dev->nvqs; ++i) {
611 if (dev->vqs[i]->error_ctx)
612 eventfd_ctx_put(dev->vqs[i]->error_ctx);
613 if (dev->vqs[i]->error)
614 fput(dev->vqs[i]->error);
615 if (dev->vqs[i]->kick)
616 fput(dev->vqs[i]->kick);
617 if (dev->vqs[i]->call_ctx)
618 eventfd_ctx_put(dev->vqs[i]->call_ctx);
619 if (dev->vqs[i]->call)
620 fput(dev->vqs[i]->call);
621 vhost_vq_reset(dev, dev->vqs[i]);
622 }
623 vhost_dev_free_iovecs(dev);
624 if (dev->log_ctx)
625 eventfd_ctx_put(dev->log_ctx);
626 dev->log_ctx = NULL;
627 if (dev->log_file)
628 fput(dev->log_file);
629 dev->log_file = NULL;
630 /* No one will access memory at this point */
631 vhost_umem_clean(dev->umem);
632 dev->umem = NULL;
633 vhost_umem_clean(dev->iotlb);
634 dev->iotlb = NULL;
635 vhost_clear_msg(dev);
636 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
637 WARN_ON(!llist_empty(&dev->work_list));
638 if (dev->worker) {
639 kthread_stop(dev->worker);
640 dev->worker = NULL;
641 }
642 if (dev->mm)
643 mmput(dev->mm);
644 dev->mm = NULL;
645 }
646 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
647
648 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
649 {
650 u64 a = addr / VHOST_PAGE_SIZE / 8;
651
652 /* Make sure 64 bit math will not overflow. */
653 if (a > ULONG_MAX - (unsigned long)log_base ||
654 a + (unsigned long)log_base > ULONG_MAX)
655 return 0;
656
657 return access_ok(VERIFY_WRITE, log_base + a,
658 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
659 }
660
661 static bool vhost_overflow(u64 uaddr, u64 size)
662 {
663 /* Make sure 64 bit math will not overflow. */
664 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
665 }
666
667 /* Caller should have vq mutex and device mutex. */
668 static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
669 int log_all)
670 {
671 struct vhost_umem_node *node;
672
673 if (!umem)
674 return 0;
675
676 list_for_each_entry(node, &umem->umem_list, link) {
677 unsigned long a = node->userspace_addr;
678
679 if (vhost_overflow(node->userspace_addr, node->size))
680 return 0;
681
682
683 if (!access_ok(VERIFY_WRITE, (void __user *)a,
684 node->size))
685 return 0;
686 else if (log_all && !log_access_ok(log_base,
687 node->start,
688 node->size))
689 return 0;
690 }
691 return 1;
692 }
693
694 /* Can we switch to this memory table? */
695 /* Caller should have device mutex but not vq mutex */
696 static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
697 int log_all)
698 {
699 int i;
700
701 for (i = 0; i < d->nvqs; ++i) {
702 int ok;
703 bool log;
704
705 mutex_lock(&d->vqs[i]->mutex);
706 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
707 /* If ring is inactive, will check when it's enabled. */
708 if (d->vqs[i]->private_data)
709 ok = vq_memory_access_ok(d->vqs[i]->log_base,
710 umem, log);
711 else
712 ok = 1;
713 mutex_unlock(&d->vqs[i]->mutex);
714 if (!ok)
715 return 0;
716 }
717 return 1;
718 }
719
720 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
721 struct iovec iov[], int iov_size, int access);
722
723 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
724 const void *from, unsigned size)
725 {
726 int ret;
727
728 if (!vq->iotlb)
729 return __copy_to_user(to, from, size);
730 else {
731 /* This function should be called after iotlb
732 * prefetch, which means we're sure that all vq
733 * could be access through iotlb. So -EAGAIN should
734 * not happen in this case.
735 */
736 /* TODO: more fast path */
737 struct iov_iter t;
738 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
739 ARRAY_SIZE(vq->iotlb_iov),
740 VHOST_ACCESS_WO);
741 if (ret < 0)
742 goto out;
743 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
744 ret = copy_to_iter(from, size, &t);
745 if (ret == size)
746 ret = 0;
747 }
748 out:
749 return ret;
750 }
751
752 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
753 void __user *from, unsigned size)
754 {
755 int ret;
756
757 if (!vq->iotlb)
758 return __copy_from_user(to, from, size);
759 else {
760 /* This function should be called after iotlb
761 * prefetch, which means we're sure that vq
762 * could be access through iotlb. So -EAGAIN should
763 * not happen in this case.
764 */
765 /* TODO: more fast path */
766 struct iov_iter f;
767 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
768 ARRAY_SIZE(vq->iotlb_iov),
769 VHOST_ACCESS_RO);
770 if (ret < 0) {
771 vq_err(vq, "IOTLB translation failure: uaddr "
772 "%p size 0x%llx\n", from,
773 (unsigned long long) size);
774 goto out;
775 }
776 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
777 ret = copy_from_iter(to, size, &f);
778 if (ret == size)
779 ret = 0;
780 }
781
782 out:
783 return ret;
784 }
785
786 static void __user *__vhost_get_user(struct vhost_virtqueue *vq,
787 void __user *addr, unsigned size)
788 {
789 int ret;
790
791 /* This function should be called after iotlb
792 * prefetch, which means we're sure that vq
793 * could be access through iotlb. So -EAGAIN should
794 * not happen in this case.
795 */
796 /* TODO: more fast path */
797 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
798 ARRAY_SIZE(vq->iotlb_iov),
799 VHOST_ACCESS_RO);
800 if (ret < 0) {
801 vq_err(vq, "IOTLB translation failure: uaddr "
802 "%p size 0x%llx\n", addr,
803 (unsigned long long) size);
804 return NULL;
805 }
806
807 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
808 vq_err(vq, "Non atomic userspace memory access: uaddr "
809 "%p size 0x%llx\n", addr,
810 (unsigned long long) size);
811 return NULL;
812 }
813
814 return vq->iotlb_iov[0].iov_base;
815 }
816
817 #define vhost_put_user(vq, x, ptr) \
818 ({ \
819 int ret = -EFAULT; \
820 if (!vq->iotlb) { \
821 ret = __put_user(x, ptr); \
822 } else { \
823 __typeof__(ptr) to = \
824 (__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
825 if (to != NULL) \
826 ret = __put_user(x, to); \
827 else \
828 ret = -EFAULT; \
829 } \
830 ret; \
831 })
832
833 #define vhost_get_user(vq, x, ptr) \
834 ({ \
835 int ret; \
836 if (!vq->iotlb) { \
837 ret = __get_user(x, ptr); \
838 } else { \
839 __typeof__(ptr) from = \
840 (__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
841 if (from != NULL) \
842 ret = __get_user(x, from); \
843 else \
844 ret = -EFAULT; \
845 } \
846 ret; \
847 })
848
849 static void vhost_dev_lock_vqs(struct vhost_dev *d)
850 {
851 int i = 0;
852 for (i = 0; i < d->nvqs; ++i)
853 mutex_lock(&d->vqs[i]->mutex);
854 }
855
856 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
857 {
858 int i = 0;
859 for (i = 0; i < d->nvqs; ++i)
860 mutex_unlock(&d->vqs[i]->mutex);
861 }
862
863 static int vhost_new_umem_range(struct vhost_umem *umem,
864 u64 start, u64 size, u64 end,
865 u64 userspace_addr, int perm)
866 {
867 struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
868
869 if (!node)
870 return -ENOMEM;
871
872 if (umem->numem == max_iotlb_entries) {
873 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
874 vhost_umem_free(umem, tmp);
875 }
876
877 node->start = start;
878 node->size = size;
879 node->last = end;
880 node->userspace_addr = userspace_addr;
881 node->perm = perm;
882 INIT_LIST_HEAD(&node->link);
883 list_add_tail(&node->link, &umem->umem_list);
884 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
885 umem->numem++;
886
887 return 0;
888 }
889
890 static void vhost_del_umem_range(struct vhost_umem *umem,
891 u64 start, u64 end)
892 {
893 struct vhost_umem_node *node;
894
895 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
896 start, end)))
897 vhost_umem_free(umem, node);
898 }
899
900 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
901 struct vhost_iotlb_msg *msg)
902 {
903 struct vhost_msg_node *node, *n;
904
905 spin_lock(&d->iotlb_lock);
906
907 list_for_each_entry_safe(node, n, &d->pending_list, node) {
908 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
909 if (msg->iova <= vq_msg->iova &&
910 msg->iova + msg->size - 1 > vq_msg->iova &&
911 vq_msg->type == VHOST_IOTLB_MISS) {
912 vhost_poll_queue(&node->vq->poll);
913 list_del(&node->node);
914 kfree(node);
915 }
916 }
917
918 spin_unlock(&d->iotlb_lock);
919 }
920
921 static int umem_access_ok(u64 uaddr, u64 size, int access)
922 {
923 unsigned long a = uaddr;
924
925 /* Make sure 64 bit math will not overflow. */
926 if (vhost_overflow(uaddr, size))
927 return -EFAULT;
928
929 if ((access & VHOST_ACCESS_RO) &&
930 !access_ok(VERIFY_READ, (void __user *)a, size))
931 return -EFAULT;
932 if ((access & VHOST_ACCESS_WO) &&
933 !access_ok(VERIFY_WRITE, (void __user *)a, size))
934 return -EFAULT;
935 return 0;
936 }
937
938 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
939 struct vhost_iotlb_msg *msg)
940 {
941 int ret = 0;
942
943 vhost_dev_lock_vqs(dev);
944 switch (msg->type) {
945 case VHOST_IOTLB_UPDATE:
946 if (!dev->iotlb) {
947 ret = -EFAULT;
948 break;
949 }
950 if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
951 ret = -EFAULT;
952 break;
953 }
954 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
955 msg->iova + msg->size - 1,
956 msg->uaddr, msg->perm)) {
957 ret = -ENOMEM;
958 break;
959 }
960 vhost_iotlb_notify_vq(dev, msg);
961 break;
962 case VHOST_IOTLB_INVALIDATE:
963 vhost_del_umem_range(dev->iotlb, msg->iova,
964 msg->iova + msg->size - 1);
965 break;
966 default:
967 ret = -EINVAL;
968 break;
969 }
970
971 vhost_dev_unlock_vqs(dev);
972 return ret;
973 }
974 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
975 struct iov_iter *from)
976 {
977 struct vhost_msg_node node;
978 unsigned size = sizeof(struct vhost_msg);
979 size_t ret;
980 int err;
981
982 if (iov_iter_count(from) < size)
983 return 0;
984 ret = copy_from_iter(&node.msg, size, from);
985 if (ret != size)
986 goto done;
987
988 switch (node.msg.type) {
989 case VHOST_IOTLB_MSG:
990 err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
991 if (err)
992 ret = err;
993 break;
994 default:
995 ret = -EINVAL;
996 break;
997 }
998
999 done:
1000 return ret;
1001 }
1002 EXPORT_SYMBOL(vhost_chr_write_iter);
1003
1004 unsigned int vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1005 poll_table *wait)
1006 {
1007 unsigned int mask = 0;
1008
1009 poll_wait(file, &dev->wait, wait);
1010
1011 if (!list_empty(&dev->read_list))
1012 mask |= POLLIN | POLLRDNORM;
1013
1014 return mask;
1015 }
1016 EXPORT_SYMBOL(vhost_chr_poll);
1017
1018 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1019 int noblock)
1020 {
1021 DEFINE_WAIT(wait);
1022 struct vhost_msg_node *node;
1023 ssize_t ret = 0;
1024 unsigned size = sizeof(struct vhost_msg);
1025
1026 if (iov_iter_count(to) < size)
1027 return 0;
1028
1029 while (1) {
1030 if (!noblock)
1031 prepare_to_wait(&dev->wait, &wait,
1032 TASK_INTERRUPTIBLE);
1033
1034 node = vhost_dequeue_msg(dev, &dev->read_list);
1035 if (node)
1036 break;
1037 if (noblock) {
1038 ret = -EAGAIN;
1039 break;
1040 }
1041 if (signal_pending(current)) {
1042 ret = -ERESTARTSYS;
1043 break;
1044 }
1045 if (!dev->iotlb) {
1046 ret = -EBADFD;
1047 break;
1048 }
1049
1050 schedule();
1051 }
1052
1053 if (!noblock)
1054 finish_wait(&dev->wait, &wait);
1055
1056 if (node) {
1057 ret = copy_to_iter(&node->msg, size, to);
1058
1059 if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {
1060 kfree(node);
1061 return ret;
1062 }
1063
1064 vhost_enqueue_msg(dev, &dev->pending_list, node);
1065 }
1066
1067 return ret;
1068 }
1069 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1070
1071 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1072 {
1073 struct vhost_dev *dev = vq->dev;
1074 struct vhost_msg_node *node;
1075 struct vhost_iotlb_msg *msg;
1076
1077 node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
1078 if (!node)
1079 return -ENOMEM;
1080
1081 msg = &node->msg.iotlb;
1082 msg->type = VHOST_IOTLB_MISS;
1083 msg->iova = iova;
1084 msg->perm = access;
1085
1086 vhost_enqueue_msg(dev, &dev->read_list, node);
1087
1088 return 0;
1089 }
1090
1091 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1092 struct vring_desc __user *desc,
1093 struct vring_avail __user *avail,
1094 struct vring_used __user *used)
1095
1096 {
1097 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1098
1099 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
1100 access_ok(VERIFY_READ, avail,
1101 sizeof *avail + num * sizeof *avail->ring + s) &&
1102 access_ok(VERIFY_WRITE, used,
1103 sizeof *used + num * sizeof *used->ring + s);
1104 }
1105
1106 static int iotlb_access_ok(struct vhost_virtqueue *vq,
1107 int access, u64 addr, u64 len)
1108 {
1109 const struct vhost_umem_node *node;
1110 struct vhost_umem *umem = vq->iotlb;
1111 u64 s = 0, size;
1112
1113 while (len > s) {
1114 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1115 addr,
1116 addr + len - 1);
1117 if (node == NULL || node->start > addr) {
1118 vhost_iotlb_miss(vq, addr, access);
1119 return false;
1120 } else if (!(node->perm & access)) {
1121 /* Report the possible access violation by
1122 * request another translation from userspace.
1123 */
1124 return false;
1125 }
1126
1127 size = node->size - addr + node->start;
1128 s += size;
1129 addr += size;
1130 }
1131
1132 return true;
1133 }
1134
1135 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1136 {
1137 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1138 unsigned int num = vq->num;
1139
1140 if (!vq->iotlb)
1141 return 1;
1142
1143 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1144 num * sizeof *vq->desc) &&
1145 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1146 sizeof *vq->avail +
1147 num * sizeof *vq->avail->ring + s) &&
1148 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1149 sizeof *vq->used +
1150 num * sizeof *vq->used->ring + s);
1151 }
1152 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1153
1154 /* Can we log writes? */
1155 /* Caller should have device mutex but not vq mutex */
1156 int vhost_log_access_ok(struct vhost_dev *dev)
1157 {
1158 return memory_access_ok(dev, dev->umem, 1);
1159 }
1160 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1161
1162 /* Verify access for write logging. */
1163 /* Caller should have vq mutex and device mutex */
1164 static int vq_log_access_ok(struct vhost_virtqueue *vq,
1165 void __user *log_base)
1166 {
1167 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1168
1169 return vq_memory_access_ok(log_base, vq->umem,
1170 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1171 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1172 sizeof *vq->used +
1173 vq->num * sizeof *vq->used->ring + s));
1174 }
1175
1176 /* Can we start vq? */
1177 /* Caller should have vq mutex and device mutex */
1178 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
1179 {
1180 if (vq->iotlb) {
1181 /* When device IOTLB was used, the access validation
1182 * will be validated during prefetching.
1183 */
1184 return 1;
1185 }
1186 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
1187 vq_log_access_ok(vq, vq->log_base);
1188 }
1189 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1190
1191 static struct vhost_umem *vhost_umem_alloc(void)
1192 {
1193 struct vhost_umem *umem = vhost_kvzalloc(sizeof(*umem));
1194
1195 if (!umem)
1196 return NULL;
1197
1198 umem->umem_tree = RB_ROOT;
1199 umem->numem = 0;
1200 INIT_LIST_HEAD(&umem->umem_list);
1201
1202 return umem;
1203 }
1204
1205 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1206 {
1207 struct vhost_memory mem, *newmem;
1208 struct vhost_memory_region *region;
1209 struct vhost_umem *newumem, *oldumem;
1210 unsigned long size = offsetof(struct vhost_memory, regions);
1211 int i;
1212
1213 if (copy_from_user(&mem, m, size))
1214 return -EFAULT;
1215 if (mem.padding)
1216 return -EOPNOTSUPP;
1217 if (mem.nregions > max_mem_regions)
1218 return -E2BIG;
1219 newmem = vhost_kvzalloc(size + mem.nregions * sizeof(*m->regions));
1220 if (!newmem)
1221 return -ENOMEM;
1222
1223 memcpy(newmem, &mem, size);
1224 if (copy_from_user(newmem->regions, m->regions,
1225 mem.nregions * sizeof *m->regions)) {
1226 kvfree(newmem);
1227 return -EFAULT;
1228 }
1229
1230 newumem = vhost_umem_alloc();
1231 if (!newumem) {
1232 kvfree(newmem);
1233 return -ENOMEM;
1234 }
1235
1236 for (region = newmem->regions;
1237 region < newmem->regions + mem.nregions;
1238 region++) {
1239 if (vhost_new_umem_range(newumem,
1240 region->guest_phys_addr,
1241 region->memory_size,
1242 region->guest_phys_addr +
1243 region->memory_size - 1,
1244 region->userspace_addr,
1245 VHOST_ACCESS_RW))
1246 goto err;
1247 }
1248
1249 if (!memory_access_ok(d, newumem, 0))
1250 goto err;
1251
1252 oldumem = d->umem;
1253 d->umem = newumem;
1254
1255 /* All memory accesses are done under some VQ mutex. */
1256 for (i = 0; i < d->nvqs; ++i) {
1257 mutex_lock(&d->vqs[i]->mutex);
1258 d->vqs[i]->umem = newumem;
1259 mutex_unlock(&d->vqs[i]->mutex);
1260 }
1261
1262 kvfree(newmem);
1263 vhost_umem_clean(oldumem);
1264 return 0;
1265
1266 err:
1267 vhost_umem_clean(newumem);
1268 kvfree(newmem);
1269 return -EFAULT;
1270 }
1271
1272 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
1273 {
1274 struct file *eventfp, *filep = NULL;
1275 bool pollstart = false, pollstop = false;
1276 struct eventfd_ctx *ctx = NULL;
1277 u32 __user *idxp = argp;
1278 struct vhost_virtqueue *vq;
1279 struct vhost_vring_state s;
1280 struct vhost_vring_file f;
1281 struct vhost_vring_addr a;
1282 u32 idx;
1283 long r;
1284
1285 r = get_user(idx, idxp);
1286 if (r < 0)
1287 return r;
1288 if (idx >= d->nvqs)
1289 return -ENOBUFS;
1290
1291 vq = d->vqs[idx];
1292
1293 mutex_lock(&vq->mutex);
1294
1295 switch (ioctl) {
1296 case VHOST_SET_VRING_NUM:
1297 /* Resizing ring with an active backend?
1298 * You don't want to do that. */
1299 if (vq->private_data) {
1300 r = -EBUSY;
1301 break;
1302 }
1303 if (copy_from_user(&s, argp, sizeof s)) {
1304 r = -EFAULT;
1305 break;
1306 }
1307 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1308 r = -EINVAL;
1309 break;
1310 }
1311 vq->num = s.num;
1312 break;
1313 case VHOST_SET_VRING_BASE:
1314 /* Moving base with an active backend?
1315 * You don't want to do that. */
1316 if (vq->private_data) {
1317 r = -EBUSY;
1318 break;
1319 }
1320 if (copy_from_user(&s, argp, sizeof s)) {
1321 r = -EFAULT;
1322 break;
1323 }
1324 if (s.num > 0xffff) {
1325 r = -EINVAL;
1326 break;
1327 }
1328 vq->last_avail_idx = vq->last_used_event = s.num;
1329 /* Forget the cached index value. */
1330 vq->avail_idx = vq->last_avail_idx;
1331 break;
1332 case VHOST_GET_VRING_BASE:
1333 s.index = idx;
1334 s.num = vq->last_avail_idx;
1335 if (copy_to_user(argp, &s, sizeof s))
1336 r = -EFAULT;
1337 break;
1338 case VHOST_SET_VRING_ADDR:
1339 if (copy_from_user(&a, argp, sizeof a)) {
1340 r = -EFAULT;
1341 break;
1342 }
1343 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1344 r = -EOPNOTSUPP;
1345 break;
1346 }
1347 /* For 32bit, verify that the top 32bits of the user
1348 data are set to zero. */
1349 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1350 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1351 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1352 r = -EFAULT;
1353 break;
1354 }
1355
1356 /* Make sure it's safe to cast pointers to vring types. */
1357 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1358 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1359 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1360 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1361 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1362 r = -EINVAL;
1363 break;
1364 }
1365
1366 /* We only verify access here if backend is configured.
1367 * If it is not, we don't as size might not have been setup.
1368 * We will verify when backend is configured. */
1369 if (vq->private_data) {
1370 if (!vq_access_ok(vq, vq->num,
1371 (void __user *)(unsigned long)a.desc_user_addr,
1372 (void __user *)(unsigned long)a.avail_user_addr,
1373 (void __user *)(unsigned long)a.used_user_addr)) {
1374 r = -EINVAL;
1375 break;
1376 }
1377
1378 /* Also validate log access for used ring if enabled. */
1379 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1380 !log_access_ok(vq->log_base, a.log_guest_addr,
1381 sizeof *vq->used +
1382 vq->num * sizeof *vq->used->ring)) {
1383 r = -EINVAL;
1384 break;
1385 }
1386 }
1387
1388 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1389 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1390 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1391 vq->log_addr = a.log_guest_addr;
1392 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1393 break;
1394 case VHOST_SET_VRING_KICK:
1395 if (copy_from_user(&f, argp, sizeof f)) {
1396 r = -EFAULT;
1397 break;
1398 }
1399 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1400 if (IS_ERR(eventfp)) {
1401 r = PTR_ERR(eventfp);
1402 break;
1403 }
1404 if (eventfp != vq->kick) {
1405 pollstop = (filep = vq->kick) != NULL;
1406 pollstart = (vq->kick = eventfp) != NULL;
1407 } else
1408 filep = eventfp;
1409 break;
1410 case VHOST_SET_VRING_CALL:
1411 if (copy_from_user(&f, argp, sizeof f)) {
1412 r = -EFAULT;
1413 break;
1414 }
1415 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1416 if (IS_ERR(eventfp)) {
1417 r = PTR_ERR(eventfp);
1418 break;
1419 }
1420 if (eventfp != vq->call) {
1421 filep = vq->call;
1422 ctx = vq->call_ctx;
1423 vq->call = eventfp;
1424 vq->call_ctx = eventfp ?
1425 eventfd_ctx_fileget(eventfp) : NULL;
1426 } else
1427 filep = eventfp;
1428 break;
1429 case VHOST_SET_VRING_ERR:
1430 if (copy_from_user(&f, argp, sizeof f)) {
1431 r = -EFAULT;
1432 break;
1433 }
1434 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1435 if (IS_ERR(eventfp)) {
1436 r = PTR_ERR(eventfp);
1437 break;
1438 }
1439 if (eventfp != vq->error) {
1440 filep = vq->error;
1441 vq->error = eventfp;
1442 ctx = vq->error_ctx;
1443 vq->error_ctx = eventfp ?
1444 eventfd_ctx_fileget(eventfp) : NULL;
1445 } else
1446 filep = eventfp;
1447 break;
1448 case VHOST_SET_VRING_ENDIAN:
1449 r = vhost_set_vring_endian(vq, argp);
1450 break;
1451 case VHOST_GET_VRING_ENDIAN:
1452 r = vhost_get_vring_endian(vq, idx, argp);
1453 break;
1454 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1455 if (copy_from_user(&s, argp, sizeof(s))) {
1456 r = -EFAULT;
1457 break;
1458 }
1459 vq->busyloop_timeout = s.num;
1460 break;
1461 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1462 s.index = idx;
1463 s.num = vq->busyloop_timeout;
1464 if (copy_to_user(argp, &s, sizeof(s)))
1465 r = -EFAULT;
1466 break;
1467 default:
1468 r = -ENOIOCTLCMD;
1469 }
1470
1471 if (pollstop && vq->handle_kick)
1472 vhost_poll_stop(&vq->poll);
1473
1474 if (ctx)
1475 eventfd_ctx_put(ctx);
1476 if (filep)
1477 fput(filep);
1478
1479 if (pollstart && vq->handle_kick)
1480 r = vhost_poll_start(&vq->poll, vq->kick);
1481
1482 mutex_unlock(&vq->mutex);
1483
1484 if (pollstop && vq->handle_kick)
1485 vhost_poll_flush(&vq->poll);
1486 return r;
1487 }
1488 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1489
1490 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1491 {
1492 struct vhost_umem *niotlb, *oiotlb;
1493 int i;
1494
1495 niotlb = vhost_umem_alloc();
1496 if (!niotlb)
1497 return -ENOMEM;
1498
1499 oiotlb = d->iotlb;
1500 d->iotlb = niotlb;
1501
1502 for (i = 0; i < d->nvqs; ++i) {
1503 mutex_lock(&d->vqs[i]->mutex);
1504 d->vqs[i]->iotlb = niotlb;
1505 mutex_unlock(&d->vqs[i]->mutex);
1506 }
1507
1508 vhost_umem_clean(oiotlb);
1509
1510 return 0;
1511 }
1512 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1513
1514 /* Caller must have device mutex */
1515 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1516 {
1517 struct file *eventfp, *filep = NULL;
1518 struct eventfd_ctx *ctx = NULL;
1519 u64 p;
1520 long r;
1521 int i, fd;
1522
1523 /* If you are not the owner, you can become one */
1524 if (ioctl == VHOST_SET_OWNER) {
1525 r = vhost_dev_set_owner(d);
1526 goto done;
1527 }
1528
1529 /* You must be the owner to do anything else */
1530 r = vhost_dev_check_owner(d);
1531 if (r)
1532 goto done;
1533
1534 switch (ioctl) {
1535 case VHOST_SET_MEM_TABLE:
1536 r = vhost_set_memory(d, argp);
1537 break;
1538 case VHOST_SET_LOG_BASE:
1539 if (copy_from_user(&p, argp, sizeof p)) {
1540 r = -EFAULT;
1541 break;
1542 }
1543 if ((u64)(unsigned long)p != p) {
1544 r = -EFAULT;
1545 break;
1546 }
1547 for (i = 0; i < d->nvqs; ++i) {
1548 struct vhost_virtqueue *vq;
1549 void __user *base = (void __user *)(unsigned long)p;
1550 vq = d->vqs[i];
1551 mutex_lock(&vq->mutex);
1552 /* If ring is inactive, will check when it's enabled. */
1553 if (vq->private_data && !vq_log_access_ok(vq, base))
1554 r = -EFAULT;
1555 else
1556 vq->log_base = base;
1557 mutex_unlock(&vq->mutex);
1558 }
1559 break;
1560 case VHOST_SET_LOG_FD:
1561 r = get_user(fd, (int __user *)argp);
1562 if (r < 0)
1563 break;
1564 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
1565 if (IS_ERR(eventfp)) {
1566 r = PTR_ERR(eventfp);
1567 break;
1568 }
1569 if (eventfp != d->log_file) {
1570 filep = d->log_file;
1571 d->log_file = eventfp;
1572 ctx = d->log_ctx;
1573 d->log_ctx = eventfp ?
1574 eventfd_ctx_fileget(eventfp) : NULL;
1575 } else
1576 filep = eventfp;
1577 for (i = 0; i < d->nvqs; ++i) {
1578 mutex_lock(&d->vqs[i]->mutex);
1579 d->vqs[i]->log_ctx = d->log_ctx;
1580 mutex_unlock(&d->vqs[i]->mutex);
1581 }
1582 if (ctx)
1583 eventfd_ctx_put(ctx);
1584 if (filep)
1585 fput(filep);
1586 break;
1587 default:
1588 r = -ENOIOCTLCMD;
1589 break;
1590 }
1591 done:
1592 return r;
1593 }
1594 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1595
1596 /* TODO: This is really inefficient. We need something like get_user()
1597 * (instruction directly accesses the data, with an exception table entry
1598 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1599 */
1600 static int set_bit_to_user(int nr, void __user *addr)
1601 {
1602 unsigned long log = (unsigned long)addr;
1603 struct page *page;
1604 void *base;
1605 int bit = nr + (log % PAGE_SIZE) * 8;
1606 int r;
1607
1608 r = get_user_pages_fast(log, 1, 1, &page);
1609 if (r < 0)
1610 return r;
1611 BUG_ON(r != 1);
1612 base = kmap_atomic(page);
1613 set_bit(bit, base);
1614 kunmap_atomic(base);
1615 set_page_dirty_lock(page);
1616 put_page(page);
1617 return 0;
1618 }
1619
1620 static int log_write(void __user *log_base,
1621 u64 write_address, u64 write_length)
1622 {
1623 u64 write_page = write_address / VHOST_PAGE_SIZE;
1624 int r;
1625
1626 if (!write_length)
1627 return 0;
1628 write_length += write_address % VHOST_PAGE_SIZE;
1629 for (;;) {
1630 u64 base = (u64)(unsigned long)log_base;
1631 u64 log = base + write_page / 8;
1632 int bit = write_page % 8;
1633 if ((u64)(unsigned long)log != log)
1634 return -EFAULT;
1635 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1636 if (r < 0)
1637 return r;
1638 if (write_length <= VHOST_PAGE_SIZE)
1639 break;
1640 write_length -= VHOST_PAGE_SIZE;
1641 write_page += 1;
1642 }
1643 return r;
1644 }
1645
1646 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1647 unsigned int log_num, u64 len)
1648 {
1649 int i, r;
1650
1651 /* Make sure data written is seen before log. */
1652 smp_wmb();
1653 for (i = 0; i < log_num; ++i) {
1654 u64 l = min(log[i].len, len);
1655 r = log_write(vq->log_base, log[i].addr, l);
1656 if (r < 0)
1657 return r;
1658 len -= l;
1659 if (!len) {
1660 if (vq->log_ctx)
1661 eventfd_signal(vq->log_ctx, 1);
1662 return 0;
1663 }
1664 }
1665 /* Length written exceeds what we have stored. This is a bug. */
1666 BUG();
1667 return 0;
1668 }
1669 EXPORT_SYMBOL_GPL(vhost_log_write);
1670
1671 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1672 {
1673 void __user *used;
1674 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1675 &vq->used->flags) < 0)
1676 return -EFAULT;
1677 if (unlikely(vq->log_used)) {
1678 /* Make sure the flag is seen before log. */
1679 smp_wmb();
1680 /* Log used flag write. */
1681 used = &vq->used->flags;
1682 log_write(vq->log_base, vq->log_addr +
1683 (used - (void __user *)vq->used),
1684 sizeof vq->used->flags);
1685 if (vq->log_ctx)
1686 eventfd_signal(vq->log_ctx, 1);
1687 }
1688 return 0;
1689 }
1690
1691 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1692 {
1693 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1694 vhost_avail_event(vq)))
1695 return -EFAULT;
1696 if (unlikely(vq->log_used)) {
1697 void __user *used;
1698 /* Make sure the event is seen before log. */
1699 smp_wmb();
1700 /* Log avail event write */
1701 used = vhost_avail_event(vq);
1702 log_write(vq->log_base, vq->log_addr +
1703 (used - (void __user *)vq->used),
1704 sizeof *vhost_avail_event(vq));
1705 if (vq->log_ctx)
1706 eventfd_signal(vq->log_ctx, 1);
1707 }
1708 return 0;
1709 }
1710
1711 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1712 {
1713 __virtio16 last_used_idx;
1714 int r;
1715 bool is_le = vq->is_le;
1716
1717 if (!vq->private_data)
1718 return 0;
1719
1720 vhost_init_is_le(vq);
1721
1722 r = vhost_update_used_flags(vq);
1723 if (r)
1724 goto err;
1725 vq->signalled_used_valid = false;
1726 if (!vq->iotlb &&
1727 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1728 r = -EFAULT;
1729 goto err;
1730 }
1731 r = vhost_get_user(vq, last_used_idx, &vq->used->idx);
1732 if (r) {
1733 vq_err(vq, "Can't access used idx at %p\n",
1734 &vq->used->idx);
1735 goto err;
1736 }
1737 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1738 return 0;
1739
1740 err:
1741 vq->is_le = is_le;
1742 return r;
1743 }
1744 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1745
1746 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1747 struct iovec iov[], int iov_size, int access)
1748 {
1749 const struct vhost_umem_node *node;
1750 struct vhost_dev *dev = vq->dev;
1751 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1752 struct iovec *_iov;
1753 u64 s = 0;
1754 int ret = 0;
1755
1756 while ((u64)len > s) {
1757 u64 size;
1758 if (unlikely(ret >= iov_size)) {
1759 ret = -ENOBUFS;
1760 break;
1761 }
1762
1763 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1764 addr, addr + len - 1);
1765 if (node == NULL || node->start > addr) {
1766 if (umem != dev->iotlb) {
1767 ret = -EFAULT;
1768 break;
1769 }
1770 ret = -EAGAIN;
1771 break;
1772 } else if (!(node->perm & access)) {
1773 ret = -EPERM;
1774 break;
1775 }
1776
1777 _iov = iov + ret;
1778 size = node->size - addr + node->start;
1779 _iov->iov_len = min((u64)len - s, size);
1780 _iov->iov_base = (void __user *)(unsigned long)
1781 (node->userspace_addr + addr - node->start);
1782 s += size;
1783 addr += size;
1784 ++ret;
1785 }
1786
1787 if (ret == -EAGAIN)
1788 vhost_iotlb_miss(vq, addr, access);
1789 return ret;
1790 }
1791
1792 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1793 * function returns the next descriptor in the chain,
1794 * or -1U if we're at the end. */
1795 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1796 {
1797 unsigned int next;
1798
1799 /* If this descriptor says it doesn't chain, we're done. */
1800 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1801 return -1U;
1802
1803 /* Check they're not leading us off end of descriptors. */
1804 next = vhost16_to_cpu(vq, desc->next);
1805 /* Make sure compiler knows to grab that: we don't want it changing! */
1806 /* We will use the result as an index in an array, so most
1807 * architectures only need a compiler barrier here. */
1808 read_barrier_depends();
1809
1810 return next;
1811 }
1812
1813 static int get_indirect(struct vhost_virtqueue *vq,
1814 struct iovec iov[], unsigned int iov_size,
1815 unsigned int *out_num, unsigned int *in_num,
1816 struct vhost_log *log, unsigned int *log_num,
1817 struct vring_desc *indirect)
1818 {
1819 struct vring_desc desc;
1820 unsigned int i = 0, count, found = 0;
1821 u32 len = vhost32_to_cpu(vq, indirect->len);
1822 struct iov_iter from;
1823 int ret, access;
1824
1825 /* Sanity check */
1826 if (unlikely(len % sizeof desc)) {
1827 vq_err(vq, "Invalid length in indirect descriptor: "
1828 "len 0x%llx not multiple of 0x%zx\n",
1829 (unsigned long long)len,
1830 sizeof desc);
1831 return -EINVAL;
1832 }
1833
1834 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1835 UIO_MAXIOV, VHOST_ACCESS_RO);
1836 if (unlikely(ret < 0)) {
1837 if (ret != -EAGAIN)
1838 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1839 return ret;
1840 }
1841 iov_iter_init(&from, READ, vq->indirect, ret, len);
1842
1843 /* We will use the result as an address to read from, so most
1844 * architectures only need a compiler barrier here. */
1845 read_barrier_depends();
1846
1847 count = len / sizeof desc;
1848 /* Buffers are chained via a 16 bit next field, so
1849 * we can have at most 2^16 of these. */
1850 if (unlikely(count > USHRT_MAX + 1)) {
1851 vq_err(vq, "Indirect buffer length too big: %d\n",
1852 indirect->len);
1853 return -E2BIG;
1854 }
1855
1856 do {
1857 unsigned iov_count = *in_num + *out_num;
1858 if (unlikely(++found > count)) {
1859 vq_err(vq, "Loop detected: last one at %u "
1860 "indirect size %u\n",
1861 i, count);
1862 return -EINVAL;
1863 }
1864 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1865 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1866 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1867 return -EINVAL;
1868 }
1869 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1870 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1871 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1872 return -EINVAL;
1873 }
1874
1875 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1876 access = VHOST_ACCESS_WO;
1877 else
1878 access = VHOST_ACCESS_RO;
1879
1880 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1881 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1882 iov_size - iov_count, access);
1883 if (unlikely(ret < 0)) {
1884 if (ret != -EAGAIN)
1885 vq_err(vq, "Translation failure %d indirect idx %d\n",
1886 ret, i);
1887 return ret;
1888 }
1889 /* If this is an input descriptor, increment that count. */
1890 if (access == VHOST_ACCESS_WO) {
1891 *in_num += ret;
1892 if (unlikely(log)) {
1893 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1894 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1895 ++*log_num;
1896 }
1897 } else {
1898 /* If it's an output descriptor, they're all supposed
1899 * to come before any input descriptors. */
1900 if (unlikely(*in_num)) {
1901 vq_err(vq, "Indirect descriptor "
1902 "has out after in: idx %d\n", i);
1903 return -EINVAL;
1904 }
1905 *out_num += ret;
1906 }
1907 } while ((i = next_desc(vq, &desc)) != -1);
1908 return 0;
1909 }
1910
1911 /* This looks in the virtqueue and for the first available buffer, and converts
1912 * it to an iovec for convenient access. Since descriptors consist of some
1913 * number of output then some number of input descriptors, it's actually two
1914 * iovecs, but we pack them into one and note how many of each there were.
1915 *
1916 * This function returns the descriptor number found, or vq->num (which is
1917 * never a valid descriptor number) if none was found. A negative code is
1918 * returned on error. */
1919 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1920 struct iovec iov[], unsigned int iov_size,
1921 unsigned int *out_num, unsigned int *in_num,
1922 struct vhost_log *log, unsigned int *log_num)
1923 {
1924 struct vring_desc desc;
1925 unsigned int i, head, found = 0;
1926 u16 last_avail_idx;
1927 __virtio16 avail_idx;
1928 __virtio16 ring_head;
1929 int ret, access;
1930
1931 /* Check it isn't doing very strange things with descriptor numbers. */
1932 last_avail_idx = vq->last_avail_idx;
1933 if (unlikely(vhost_get_user(vq, avail_idx, &vq->avail->idx))) {
1934 vq_err(vq, "Failed to access avail idx at %p\n",
1935 &vq->avail->idx);
1936 return -EFAULT;
1937 }
1938 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1939
1940 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1941 vq_err(vq, "Guest moved used index from %u to %u",
1942 last_avail_idx, vq->avail_idx);
1943 return -EFAULT;
1944 }
1945
1946 /* If there's nothing new since last we looked, return invalid. */
1947 if (vq->avail_idx == last_avail_idx)
1948 return vq->num;
1949
1950 /* Only get avail ring entries after they have been exposed by guest. */
1951 smp_rmb();
1952
1953 /* Grab the next descriptor number they're advertising, and increment
1954 * the index we've seen. */
1955 if (unlikely(vhost_get_user(vq, ring_head,
1956 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
1957 vq_err(vq, "Failed to read head: idx %d address %p\n",
1958 last_avail_idx,
1959 &vq->avail->ring[last_avail_idx % vq->num]);
1960 return -EFAULT;
1961 }
1962
1963 head = vhost16_to_cpu(vq, ring_head);
1964
1965 /* If their number is silly, that's an error. */
1966 if (unlikely(head >= vq->num)) {
1967 vq_err(vq, "Guest says index %u > %u is available",
1968 head, vq->num);
1969 return -EINVAL;
1970 }
1971
1972 /* When we start there are none of either input nor output. */
1973 *out_num = *in_num = 0;
1974 if (unlikely(log))
1975 *log_num = 0;
1976
1977 i = head;
1978 do {
1979 unsigned iov_count = *in_num + *out_num;
1980 if (unlikely(i >= vq->num)) {
1981 vq_err(vq, "Desc index is %u > %u, head = %u",
1982 i, vq->num, head);
1983 return -EINVAL;
1984 }
1985 if (unlikely(++found > vq->num)) {
1986 vq_err(vq, "Loop detected: last one at %u "
1987 "vq size %u head %u\n",
1988 i, vq->num, head);
1989 return -EINVAL;
1990 }
1991 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
1992 sizeof desc);
1993 if (unlikely(ret)) {
1994 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1995 i, vq->desc + i);
1996 return -EFAULT;
1997 }
1998 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
1999 ret = get_indirect(vq, iov, iov_size,
2000 out_num, in_num,
2001 log, log_num, &desc);
2002 if (unlikely(ret < 0)) {
2003 if (ret != -EAGAIN)
2004 vq_err(vq, "Failure detected "
2005 "in indirect descriptor at idx %d\n", i);
2006 return ret;
2007 }
2008 continue;
2009 }
2010
2011 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2012 access = VHOST_ACCESS_WO;
2013 else
2014 access = VHOST_ACCESS_RO;
2015 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2016 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2017 iov_size - iov_count, access);
2018 if (unlikely(ret < 0)) {
2019 if (ret != -EAGAIN)
2020 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2021 ret, i);
2022 return ret;
2023 }
2024 if (access == VHOST_ACCESS_WO) {
2025 /* If this is an input descriptor,
2026 * increment that count. */
2027 *in_num += ret;
2028 if (unlikely(log)) {
2029 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2030 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2031 ++*log_num;
2032 }
2033 } else {
2034 /* If it's an output descriptor, they're all supposed
2035 * to come before any input descriptors. */
2036 if (unlikely(*in_num)) {
2037 vq_err(vq, "Descriptor has out after in: "
2038 "idx %d\n", i);
2039 return -EINVAL;
2040 }
2041 *out_num += ret;
2042 }
2043 } while ((i = next_desc(vq, &desc)) != -1);
2044
2045 /* On success, increment avail index. */
2046 vq->last_avail_idx++;
2047
2048 /* Assume notifications from guest are disabled at this point,
2049 * if they aren't we would need to update avail_event index. */
2050 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2051 return head;
2052 }
2053 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2054
2055 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2056 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2057 {
2058 vq->last_avail_idx -= n;
2059 }
2060 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2061
2062 /* After we've used one of their buffers, we tell them about it. We'll then
2063 * want to notify the guest, using eventfd. */
2064 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2065 {
2066 struct vring_used_elem heads = {
2067 cpu_to_vhost32(vq, head),
2068 cpu_to_vhost32(vq, len)
2069 };
2070
2071 return vhost_add_used_n(vq, &heads, 1);
2072 }
2073 EXPORT_SYMBOL_GPL(vhost_add_used);
2074
2075 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2076 struct vring_used_elem *heads,
2077 unsigned count)
2078 {
2079 struct vring_used_elem __user *used;
2080 u16 old, new;
2081 int start;
2082
2083 start = vq->last_used_idx & (vq->num - 1);
2084 used = vq->used->ring + start;
2085 if (count == 1) {
2086 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2087 vq_err(vq, "Failed to write used id");
2088 return -EFAULT;
2089 }
2090 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2091 vq_err(vq, "Failed to write used len");
2092 return -EFAULT;
2093 }
2094 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2095 vq_err(vq, "Failed to write used");
2096 return -EFAULT;
2097 }
2098 if (unlikely(vq->log_used)) {
2099 /* Make sure data is seen before log. */
2100 smp_wmb();
2101 /* Log used ring entry write. */
2102 log_write(vq->log_base,
2103 vq->log_addr +
2104 ((void __user *)used - (void __user *)vq->used),
2105 count * sizeof *used);
2106 }
2107 old = vq->last_used_idx;
2108 new = (vq->last_used_idx += count);
2109 /* If the driver never bothers to signal in a very long while,
2110 * used index might wrap around. If that happens, invalidate
2111 * signalled_used index we stored. TODO: make sure driver
2112 * signals at least once in 2^16 and remove this. */
2113 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2114 vq->signalled_used_valid = false;
2115 return 0;
2116 }
2117
2118 /* After we've used one of their buffers, we tell them about it. We'll then
2119 * want to notify the guest, using eventfd. */
2120 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2121 unsigned count)
2122 {
2123 int start, n, r;
2124
2125 start = vq->last_used_idx & (vq->num - 1);
2126 n = vq->num - start;
2127 if (n < count) {
2128 r = __vhost_add_used_n(vq, heads, n);
2129 if (r < 0)
2130 return r;
2131 heads += n;
2132 count -= n;
2133 }
2134 r = __vhost_add_used_n(vq, heads, count);
2135
2136 /* Make sure buffer is written before we update index. */
2137 smp_wmb();
2138 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2139 &vq->used->idx)) {
2140 vq_err(vq, "Failed to increment used idx");
2141 return -EFAULT;
2142 }
2143 if (unlikely(vq->log_used)) {
2144 /* Log used index update. */
2145 log_write(vq->log_base,
2146 vq->log_addr + offsetof(struct vring_used, idx),
2147 sizeof vq->used->idx);
2148 if (vq->log_ctx)
2149 eventfd_signal(vq->log_ctx, 1);
2150 }
2151 return r;
2152 }
2153 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2154
2155 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2156 {
2157 __u16 old, new;
2158 __virtio16 event;
2159 bool v;
2160
2161 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2162 unlikely(vq->avail_idx == vq->last_avail_idx))
2163 return true;
2164
2165 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2166 __virtio16 flags;
2167 /* Flush out used index updates. This is paired
2168 * with the barrier that the Guest executes when enabling
2169 * interrupts. */
2170 smp_mb();
2171 if (vhost_get_user(vq, flags, &vq->avail->flags)) {
2172 vq_err(vq, "Failed to get flags");
2173 return true;
2174 }
2175 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2176 }
2177 old = vq->signalled_used;
2178 v = vq->signalled_used_valid;
2179 new = vq->signalled_used = vq->last_used_idx;
2180 vq->signalled_used_valid = true;
2181
2182 if (unlikely(!v))
2183 return true;
2184
2185 /* We're sure if the following conditions are met, there's no
2186 * need to notify guest:
2187 * 1) cached used event is ahead of new
2188 * 2) old to new updating does not cross cached used event. */
2189 if (vring_need_event(vq->last_used_event, new + vq->num, new) &&
2190 !vring_need_event(vq->last_used_event, new, old))
2191 return false;
2192
2193 /* Flush out used index updates. This is paired
2194 * with the barrier that the Guest executes when enabling
2195 * interrupts. */
2196 smp_mb();
2197
2198 if (vhost_get_user(vq, event, vhost_used_event(vq))) {
2199 vq_err(vq, "Failed to get used event idx");
2200 return true;
2201 }
2202 vq->last_used_event = vhost16_to_cpu(vq, event);
2203
2204 return vring_need_event(vq->last_used_event, new, old);
2205 }
2206
2207 /* This actually signals the guest, using eventfd. */
2208 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2209 {
2210 /* Signal the Guest tell them we used something up. */
2211 if (vq->call_ctx && vhost_notify(dev, vq))
2212 eventfd_signal(vq->call_ctx, 1);
2213 }
2214 EXPORT_SYMBOL_GPL(vhost_signal);
2215
2216 /* And here's the combo meal deal. Supersize me! */
2217 void vhost_add_used_and_signal(struct vhost_dev *dev,
2218 struct vhost_virtqueue *vq,
2219 unsigned int head, int len)
2220 {
2221 vhost_add_used(vq, head, len);
2222 vhost_signal(dev, vq);
2223 }
2224 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2225
2226 /* multi-buffer version of vhost_add_used_and_signal */
2227 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2228 struct vhost_virtqueue *vq,
2229 struct vring_used_elem *heads, unsigned count)
2230 {
2231 vhost_add_used_n(vq, heads, count);
2232 vhost_signal(dev, vq);
2233 }
2234 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2235
2236 /* return true if we're sure that avaiable ring is empty */
2237 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2238 {
2239 __virtio16 avail_idx;
2240 int r;
2241
2242 r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
2243 if (r)
2244 return false;
2245
2246 return vhost16_to_cpu(vq, avail_idx) == vq->avail_idx;
2247 }
2248 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2249
2250 /* OK, now we need to know about added descriptors. */
2251 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2252 {
2253 __virtio16 avail_idx;
2254 int r;
2255
2256 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2257 return false;
2258 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2259 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2260 r = vhost_update_used_flags(vq);
2261 if (r) {
2262 vq_err(vq, "Failed to enable notification at %p: %d\n",
2263 &vq->used->flags, r);
2264 return false;
2265 }
2266 } else {
2267 r = vhost_update_avail_event(vq, vq->avail_idx);
2268 if (r) {
2269 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2270 vhost_avail_event(vq), r);
2271 return false;
2272 }
2273 }
2274 /* They could have slipped one in as we were doing that: make
2275 * sure it's written, then check again. */
2276 smp_mb();
2277 r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
2278 if (r) {
2279 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2280 &vq->avail->idx, r);
2281 return false;
2282 }
2283
2284 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2285 }
2286 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2287
2288 /* We don't need to be notified again. */
2289 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2290 {
2291 int r;
2292
2293 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2294 return;
2295 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2296 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2297 r = vhost_update_used_flags(vq);
2298 if (r)
2299 vq_err(vq, "Failed to enable notification at %p: %d\n",
2300 &vq->used->flags, r);
2301 }
2302 }
2303 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2304
2305 /* Create a new message. */
2306 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2307 {
2308 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2309 if (!node)
2310 return NULL;
2311 node->vq = vq;
2312 node->msg.type = type;
2313 return node;
2314 }
2315 EXPORT_SYMBOL_GPL(vhost_new_msg);
2316
2317 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2318 struct vhost_msg_node *node)
2319 {
2320 spin_lock(&dev->iotlb_lock);
2321 list_add_tail(&node->node, head);
2322 spin_unlock(&dev->iotlb_lock);
2323
2324 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
2325 }
2326 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2327
2328 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2329 struct list_head *head)
2330 {
2331 struct vhost_msg_node *node = NULL;
2332
2333 spin_lock(&dev->iotlb_lock);
2334 if (!list_empty(head)) {
2335 node = list_first_entry(head, struct vhost_msg_node,
2336 node);
2337 list_del(&node->node);
2338 }
2339 spin_unlock(&dev->iotlb_lock);
2340
2341 return node;
2342 }
2343 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2344
2345
2346 static int __init vhost_init(void)
2347 {
2348 return 0;
2349 }
2350
2351 static void __exit vhost_exit(void)
2352 {
2353 }
2354
2355 module_init(vhost_init);
2356 module_exit(vhost_exit);
2357
2358 MODULE_VERSION("0.0.1");
2359 MODULE_LICENSE("GPL v2");
2360 MODULE_AUTHOR("Michael S. Tsirkin");
2361 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
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