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