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Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
[mirror_ubuntu-focal-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/sched/mm.h>
31 #include <linux/sched/signal.h>
32 #include <linux/interval_tree_generic.h>
33
34 #include "vhost.h"
35
36 static ushort max_mem_regions = 64;
37 module_param(max_mem_regions, ushort, 0444);
38 MODULE_PARM_DESC(max_mem_regions,
39 "Maximum number of memory regions in memory map. (default: 64)");
40 static int max_iotlb_entries = 2048;
41 module_param(max_iotlb_entries, int, 0444);
42 MODULE_PARM_DESC(max_iotlb_entries,
43 "Maximum number of iotlb entries. (default: 2048)");
44
45 enum {
46 VHOST_MEMORY_F_LOG = 0x1,
47 };
48
49 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
50 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
51
52 INTERVAL_TREE_DEFINE(struct vhost_umem_node,
53 rb, __u64, __subtree_last,
54 START, LAST, static inline, vhost_umem_interval_tree);
55
56 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
57 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
58 {
59 vq->user_be = !virtio_legacy_is_little_endian();
60 }
61
62 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
63 {
64 vq->user_be = true;
65 }
66
67 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
68 {
69 vq->user_be = false;
70 }
71
72 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
73 {
74 struct vhost_vring_state s;
75
76 if (vq->private_data)
77 return -EBUSY;
78
79 if (copy_from_user(&s, argp, sizeof(s)))
80 return -EFAULT;
81
82 if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
83 s.num != VHOST_VRING_BIG_ENDIAN)
84 return -EINVAL;
85
86 if (s.num == VHOST_VRING_BIG_ENDIAN)
87 vhost_enable_cross_endian_big(vq);
88 else
89 vhost_enable_cross_endian_little(vq);
90
91 return 0;
92 }
93
94 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
95 int __user *argp)
96 {
97 struct vhost_vring_state s = {
98 .index = idx,
99 .num = vq->user_be
100 };
101
102 if (copy_to_user(argp, &s, sizeof(s)))
103 return -EFAULT;
104
105 return 0;
106 }
107
108 static void vhost_init_is_le(struct vhost_virtqueue *vq)
109 {
110 /* Note for legacy virtio: user_be is initialized at reset time
111 * according to the host endianness. If userspace does not set an
112 * explicit endianness, the default behavior is native endian, as
113 * expected by legacy virtio.
114 */
115 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
116 }
117 #else
118 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
119 {
120 }
121
122 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
123 {
124 return -ENOIOCTLCMD;
125 }
126
127 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
128 int __user *argp)
129 {
130 return -ENOIOCTLCMD;
131 }
132
133 static void vhost_init_is_le(struct vhost_virtqueue *vq)
134 {
135 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
136 || virtio_legacy_is_little_endian();
137 }
138 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
139
140 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
141 {
142 vhost_init_is_le(vq);
143 }
144
145 struct vhost_flush_struct {
146 struct vhost_work work;
147 struct completion wait_event;
148 };
149
150 static void vhost_flush_work(struct vhost_work *work)
151 {
152 struct vhost_flush_struct *s;
153
154 s = container_of(work, struct vhost_flush_struct, work);
155 complete(&s->wait_event);
156 }
157
158 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
159 poll_table *pt)
160 {
161 struct vhost_poll *poll;
162
163 poll = container_of(pt, struct vhost_poll, table);
164 poll->wqh = wqh;
165 add_wait_queue(wqh, &poll->wait);
166 }
167
168 static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
169 void *key)
170 {
171 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
172
173 if (!(key_to_poll(key) & poll->mask))
174 return 0;
175
176 vhost_poll_queue(poll);
177 return 0;
178 }
179
180 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
181 {
182 clear_bit(VHOST_WORK_QUEUED, &work->flags);
183 work->fn = fn;
184 }
185 EXPORT_SYMBOL_GPL(vhost_work_init);
186
187 /* Init poll structure */
188 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
189 __poll_t mask, struct vhost_dev *dev)
190 {
191 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
192 init_poll_funcptr(&poll->table, vhost_poll_func);
193 poll->mask = mask;
194 poll->dev = dev;
195 poll->wqh = NULL;
196
197 vhost_work_init(&poll->work, fn);
198 }
199 EXPORT_SYMBOL_GPL(vhost_poll_init);
200
201 /* Start polling a file. We add ourselves to file's wait queue. The caller must
202 * keep a reference to a file until after vhost_poll_stop is called. */
203 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
204 {
205 __poll_t mask;
206 int ret = 0;
207
208 if (poll->wqh)
209 return 0;
210
211 mask = file->f_op->poll(file, &poll->table);
212 if (mask)
213 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
214 if (mask & EPOLLERR) {
215 vhost_poll_stop(poll);
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_meta_reset(struct vhost_virtqueue *vq)
286 {
287 int j;
288
289 for (j = 0; j < VHOST_NUM_ADDRS; j++)
290 vq->meta_iotlb[j] = NULL;
291 }
292
293 static void vhost_vq_meta_reset(struct vhost_dev *d)
294 {
295 int i;
296
297 for (i = 0; i < d->nvqs; ++i)
298 __vhost_vq_meta_reset(d->vqs[i]);
299 }
300
301 static void vhost_vq_reset(struct vhost_dev *dev,
302 struct vhost_virtqueue *vq)
303 {
304 vq->num = 1;
305 vq->desc = NULL;
306 vq->avail = NULL;
307 vq->used = NULL;
308 vq->last_avail_idx = 0;
309 vq->avail_idx = 0;
310 vq->last_used_idx = 0;
311 vq->signalled_used = 0;
312 vq->signalled_used_valid = false;
313 vq->used_flags = 0;
314 vq->log_used = false;
315 vq->log_addr = -1ull;
316 vq->private_data = NULL;
317 vq->acked_features = 0;
318 vq->log_base = NULL;
319 vq->error_ctx = NULL;
320 vq->kick = NULL;
321 vq->call_ctx = NULL;
322 vq->log_ctx = NULL;
323 vhost_reset_is_le(vq);
324 vhost_disable_cross_endian(vq);
325 vq->busyloop_timeout = 0;
326 vq->umem = NULL;
327 vq->iotlb = NULL;
328 __vhost_vq_meta_reset(vq);
329 }
330
331 static int vhost_worker(void *data)
332 {
333 struct vhost_dev *dev = data;
334 struct vhost_work *work, *work_next;
335 struct llist_node *node;
336 mm_segment_t oldfs = get_fs();
337
338 set_fs(USER_DS);
339 use_mm(dev->mm);
340
341 for (;;) {
342 /* mb paired w/ kthread_stop */
343 set_current_state(TASK_INTERRUPTIBLE);
344
345 if (kthread_should_stop()) {
346 __set_current_state(TASK_RUNNING);
347 break;
348 }
349
350 node = llist_del_all(&dev->work_list);
351 if (!node)
352 schedule();
353
354 node = llist_reverse_order(node);
355 /* make sure flag is seen after deletion */
356 smp_wmb();
357 llist_for_each_entry_safe(work, work_next, node, node) {
358 clear_bit(VHOST_WORK_QUEUED, &work->flags);
359 __set_current_state(TASK_RUNNING);
360 work->fn(work);
361 if (need_resched())
362 schedule();
363 }
364 }
365 unuse_mm(dev->mm);
366 set_fs(oldfs);
367 return 0;
368 }
369
370 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
371 {
372 kfree(vq->indirect);
373 vq->indirect = NULL;
374 kfree(vq->log);
375 vq->log = NULL;
376 kfree(vq->heads);
377 vq->heads = NULL;
378 }
379
380 /* Helper to allocate iovec buffers for all vqs. */
381 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
382 {
383 struct vhost_virtqueue *vq;
384 int i;
385
386 for (i = 0; i < dev->nvqs; ++i) {
387 vq = dev->vqs[i];
388 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
389 GFP_KERNEL);
390 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
391 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
392 if (!vq->indirect || !vq->log || !vq->heads)
393 goto err_nomem;
394 }
395 return 0;
396
397 err_nomem:
398 for (; i >= 0; --i)
399 vhost_vq_free_iovecs(dev->vqs[i]);
400 return -ENOMEM;
401 }
402
403 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
404 {
405 int i;
406
407 for (i = 0; i < dev->nvqs; ++i)
408 vhost_vq_free_iovecs(dev->vqs[i]);
409 }
410
411 void vhost_dev_init(struct vhost_dev *dev,
412 struct vhost_virtqueue **vqs, int nvqs)
413 {
414 struct vhost_virtqueue *vq;
415 int i;
416
417 dev->vqs = vqs;
418 dev->nvqs = nvqs;
419 mutex_init(&dev->mutex);
420 dev->log_ctx = NULL;
421 dev->umem = NULL;
422 dev->iotlb = NULL;
423 dev->mm = NULL;
424 dev->worker = NULL;
425 init_llist_head(&dev->work_list);
426 init_waitqueue_head(&dev->wait);
427 INIT_LIST_HEAD(&dev->read_list);
428 INIT_LIST_HEAD(&dev->pending_list);
429 spin_lock_init(&dev->iotlb_lock);
430
431
432 for (i = 0; i < dev->nvqs; ++i) {
433 vq = dev->vqs[i];
434 vq->log = NULL;
435 vq->indirect = NULL;
436 vq->heads = NULL;
437 vq->dev = dev;
438 mutex_init(&vq->mutex);
439 vhost_vq_reset(dev, vq);
440 if (vq->handle_kick)
441 vhost_poll_init(&vq->poll, vq->handle_kick,
442 EPOLLIN, dev);
443 }
444 }
445 EXPORT_SYMBOL_GPL(vhost_dev_init);
446
447 /* Caller should have device mutex */
448 long vhost_dev_check_owner(struct vhost_dev *dev)
449 {
450 /* Are you the owner? If not, I don't think you mean to do that */
451 return dev->mm == current->mm ? 0 : -EPERM;
452 }
453 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
454
455 struct vhost_attach_cgroups_struct {
456 struct vhost_work work;
457 struct task_struct *owner;
458 int ret;
459 };
460
461 static void vhost_attach_cgroups_work(struct vhost_work *work)
462 {
463 struct vhost_attach_cgroups_struct *s;
464
465 s = container_of(work, struct vhost_attach_cgroups_struct, work);
466 s->ret = cgroup_attach_task_all(s->owner, current);
467 }
468
469 static int vhost_attach_cgroups(struct vhost_dev *dev)
470 {
471 struct vhost_attach_cgroups_struct attach;
472
473 attach.owner = current;
474 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
475 vhost_work_queue(dev, &attach.work);
476 vhost_work_flush(dev, &attach.work);
477 return attach.ret;
478 }
479
480 /* Caller should have device mutex */
481 bool vhost_dev_has_owner(struct vhost_dev *dev)
482 {
483 return dev->mm;
484 }
485 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
486
487 /* Caller should have device mutex */
488 long vhost_dev_set_owner(struct vhost_dev *dev)
489 {
490 struct task_struct *worker;
491 int err;
492
493 /* Is there an owner already? */
494 if (vhost_dev_has_owner(dev)) {
495 err = -EBUSY;
496 goto err_mm;
497 }
498
499 /* No owner, become one */
500 dev->mm = get_task_mm(current);
501 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
502 if (IS_ERR(worker)) {
503 err = PTR_ERR(worker);
504 goto err_worker;
505 }
506
507 dev->worker = worker;
508 wake_up_process(worker); /* avoid contributing to loadavg */
509
510 err = vhost_attach_cgroups(dev);
511 if (err)
512 goto err_cgroup;
513
514 err = vhost_dev_alloc_iovecs(dev);
515 if (err)
516 goto err_cgroup;
517
518 return 0;
519 err_cgroup:
520 kthread_stop(worker);
521 dev->worker = NULL;
522 err_worker:
523 if (dev->mm)
524 mmput(dev->mm);
525 dev->mm = NULL;
526 err_mm:
527 return err;
528 }
529 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
530
531 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
532 {
533 return kvzalloc(sizeof(struct vhost_umem), GFP_KERNEL);
534 }
535 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
536
537 /* Caller should have device mutex */
538 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
539 {
540 int i;
541
542 vhost_dev_cleanup(dev);
543
544 /* Restore memory to default empty mapping. */
545 INIT_LIST_HEAD(&umem->umem_list);
546 dev->umem = umem;
547 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
548 * VQs aren't running.
549 */
550 for (i = 0; i < dev->nvqs; ++i)
551 dev->vqs[i]->umem = umem;
552 }
553 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
554
555 void vhost_dev_stop(struct vhost_dev *dev)
556 {
557 int i;
558
559 for (i = 0; i < dev->nvqs; ++i) {
560 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
561 vhost_poll_stop(&dev->vqs[i]->poll);
562 vhost_poll_flush(&dev->vqs[i]->poll);
563 }
564 }
565 }
566 EXPORT_SYMBOL_GPL(vhost_dev_stop);
567
568 static void vhost_umem_free(struct vhost_umem *umem,
569 struct vhost_umem_node *node)
570 {
571 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
572 list_del(&node->link);
573 kfree(node);
574 umem->numem--;
575 }
576
577 static void vhost_umem_clean(struct vhost_umem *umem)
578 {
579 struct vhost_umem_node *node, *tmp;
580
581 if (!umem)
582 return;
583
584 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
585 vhost_umem_free(umem, node);
586
587 kvfree(umem);
588 }
589
590 static void vhost_clear_msg(struct vhost_dev *dev)
591 {
592 struct vhost_msg_node *node, *n;
593
594 spin_lock(&dev->iotlb_lock);
595
596 list_for_each_entry_safe(node, n, &dev->read_list, node) {
597 list_del(&node->node);
598 kfree(node);
599 }
600
601 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
602 list_del(&node->node);
603 kfree(node);
604 }
605
606 spin_unlock(&dev->iotlb_lock);
607 }
608
609 void vhost_dev_cleanup(struct vhost_dev *dev)
610 {
611 int i;
612
613 for (i = 0; i < dev->nvqs; ++i) {
614 if (dev->vqs[i]->error_ctx)
615 eventfd_ctx_put(dev->vqs[i]->error_ctx);
616 if (dev->vqs[i]->kick)
617 fput(dev->vqs[i]->kick);
618 if (dev->vqs[i]->call_ctx)
619 eventfd_ctx_put(dev->vqs[i]->call_ctx);
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 /* No one will access memory at this point */
627 vhost_umem_clean(dev->umem);
628 dev->umem = NULL;
629 vhost_umem_clean(dev->iotlb);
630 dev->iotlb = NULL;
631 vhost_clear_msg(dev);
632 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
633 WARN_ON(!llist_empty(&dev->work_list));
634 if (dev->worker) {
635 kthread_stop(dev->worker);
636 dev->worker = NULL;
637 }
638 if (dev->mm)
639 mmput(dev->mm);
640 dev->mm = NULL;
641 }
642 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
643
644 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
645 {
646 u64 a = addr / VHOST_PAGE_SIZE / 8;
647
648 /* Make sure 64 bit math will not overflow. */
649 if (a > ULONG_MAX - (unsigned long)log_base ||
650 a + (unsigned long)log_base > ULONG_MAX)
651 return 0;
652
653 return access_ok(VERIFY_WRITE, log_base + a,
654 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
655 }
656
657 static bool vhost_overflow(u64 uaddr, u64 size)
658 {
659 /* Make sure 64 bit math will not overflow. */
660 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
661 }
662
663 /* Caller should have vq mutex and device mutex. */
664 static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
665 int log_all)
666 {
667 struct vhost_umem_node *node;
668
669 if (!umem)
670 return 0;
671
672 list_for_each_entry(node, &umem->umem_list, link) {
673 unsigned long a = node->userspace_addr;
674
675 if (vhost_overflow(node->userspace_addr, node->size))
676 return 0;
677
678
679 if (!access_ok(VERIFY_WRITE, (void __user *)a,
680 node->size))
681 return 0;
682 else if (log_all && !log_access_ok(log_base,
683 node->start,
684 node->size))
685 return 0;
686 }
687 return 1;
688 }
689
690 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
691 u64 addr, unsigned int size,
692 int type)
693 {
694 const struct vhost_umem_node *node = vq->meta_iotlb[type];
695
696 if (!node)
697 return NULL;
698
699 return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
700 }
701
702 /* Can we switch to this memory table? */
703 /* Caller should have device mutex but not vq mutex */
704 static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
705 int log_all)
706 {
707 int i;
708
709 for (i = 0; i < d->nvqs; ++i) {
710 int ok;
711 bool log;
712
713 mutex_lock(&d->vqs[i]->mutex);
714 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
715 /* If ring is inactive, will check when it's enabled. */
716 if (d->vqs[i]->private_data)
717 ok = vq_memory_access_ok(d->vqs[i]->log_base,
718 umem, log);
719 else
720 ok = 1;
721 mutex_unlock(&d->vqs[i]->mutex);
722 if (!ok)
723 return 0;
724 }
725 return 1;
726 }
727
728 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
729 struct iovec iov[], int iov_size, int access);
730
731 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
732 const void *from, unsigned size)
733 {
734 int ret;
735
736 if (!vq->iotlb)
737 return __copy_to_user(to, from, size);
738 else {
739 /* This function should be called after iotlb
740 * prefetch, which means we're sure that all vq
741 * could be access through iotlb. So -EAGAIN should
742 * not happen in this case.
743 */
744 struct iov_iter t;
745 void __user *uaddr = vhost_vq_meta_fetch(vq,
746 (u64)(uintptr_t)to, size,
747 VHOST_ADDR_DESC);
748
749 if (uaddr)
750 return __copy_to_user(uaddr, from, size);
751
752 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
753 ARRAY_SIZE(vq->iotlb_iov),
754 VHOST_ACCESS_WO);
755 if (ret < 0)
756 goto out;
757 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
758 ret = copy_to_iter(from, size, &t);
759 if (ret == size)
760 ret = 0;
761 }
762 out:
763 return ret;
764 }
765
766 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
767 void __user *from, unsigned size)
768 {
769 int ret;
770
771 if (!vq->iotlb)
772 return __copy_from_user(to, from, size);
773 else {
774 /* This function should be called after iotlb
775 * prefetch, which means we're sure that vq
776 * could be access through iotlb. So -EAGAIN should
777 * not happen in this case.
778 */
779 void __user *uaddr = vhost_vq_meta_fetch(vq,
780 (u64)(uintptr_t)from, size,
781 VHOST_ADDR_DESC);
782 struct iov_iter f;
783
784 if (uaddr)
785 return __copy_from_user(to, uaddr, size);
786
787 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
788 ARRAY_SIZE(vq->iotlb_iov),
789 VHOST_ACCESS_RO);
790 if (ret < 0) {
791 vq_err(vq, "IOTLB translation failure: uaddr "
792 "%p size 0x%llx\n", from,
793 (unsigned long long) size);
794 goto out;
795 }
796 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
797 ret = copy_from_iter(to, size, &f);
798 if (ret == size)
799 ret = 0;
800 }
801
802 out:
803 return ret;
804 }
805
806 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
807 void __user *addr, unsigned int size,
808 int type)
809 {
810 int ret;
811
812 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
813 ARRAY_SIZE(vq->iotlb_iov),
814 VHOST_ACCESS_RO);
815 if (ret < 0) {
816 vq_err(vq, "IOTLB translation failure: uaddr "
817 "%p size 0x%llx\n", addr,
818 (unsigned long long) size);
819 return NULL;
820 }
821
822 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
823 vq_err(vq, "Non atomic userspace memory access: uaddr "
824 "%p size 0x%llx\n", addr,
825 (unsigned long long) size);
826 return NULL;
827 }
828
829 return vq->iotlb_iov[0].iov_base;
830 }
831
832 /* This function should be called after iotlb
833 * prefetch, which means we're sure that vq
834 * could be access through iotlb. So -EAGAIN should
835 * not happen in this case.
836 */
837 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
838 void *addr, unsigned int size,
839 int type)
840 {
841 void __user *uaddr = vhost_vq_meta_fetch(vq,
842 (u64)(uintptr_t)addr, size, type);
843 if (uaddr)
844 return uaddr;
845
846 return __vhost_get_user_slow(vq, addr, size, type);
847 }
848
849 #define vhost_put_user(vq, x, ptr) \
850 ({ \
851 int ret = -EFAULT; \
852 if (!vq->iotlb) { \
853 ret = __put_user(x, ptr); \
854 } else { \
855 __typeof__(ptr) to = \
856 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
857 sizeof(*ptr), VHOST_ADDR_USED); \
858 if (to != NULL) \
859 ret = __put_user(x, to); \
860 else \
861 ret = -EFAULT; \
862 } \
863 ret; \
864 })
865
866 #define vhost_get_user(vq, x, ptr, type) \
867 ({ \
868 int ret; \
869 if (!vq->iotlb) { \
870 ret = __get_user(x, ptr); \
871 } else { \
872 __typeof__(ptr) from = \
873 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
874 sizeof(*ptr), \
875 type); \
876 if (from != NULL) \
877 ret = __get_user(x, from); \
878 else \
879 ret = -EFAULT; \
880 } \
881 ret; \
882 })
883
884 #define vhost_get_avail(vq, x, ptr) \
885 vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
886
887 #define vhost_get_used(vq, x, ptr) \
888 vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
889
890 static void vhost_dev_lock_vqs(struct vhost_dev *d)
891 {
892 int i = 0;
893 for (i = 0; i < d->nvqs; ++i)
894 mutex_lock_nested(&d->vqs[i]->mutex, i);
895 }
896
897 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
898 {
899 int i = 0;
900 for (i = 0; i < d->nvqs; ++i)
901 mutex_unlock(&d->vqs[i]->mutex);
902 }
903
904 static int vhost_new_umem_range(struct vhost_umem *umem,
905 u64 start, u64 size, u64 end,
906 u64 userspace_addr, int perm)
907 {
908 struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
909
910 if (!node)
911 return -ENOMEM;
912
913 if (umem->numem == max_iotlb_entries) {
914 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
915 vhost_umem_free(umem, tmp);
916 }
917
918 node->start = start;
919 node->size = size;
920 node->last = end;
921 node->userspace_addr = userspace_addr;
922 node->perm = perm;
923 INIT_LIST_HEAD(&node->link);
924 list_add_tail(&node->link, &umem->umem_list);
925 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
926 umem->numem++;
927
928 return 0;
929 }
930
931 static void vhost_del_umem_range(struct vhost_umem *umem,
932 u64 start, u64 end)
933 {
934 struct vhost_umem_node *node;
935
936 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
937 start, end)))
938 vhost_umem_free(umem, node);
939 }
940
941 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
942 struct vhost_iotlb_msg *msg)
943 {
944 struct vhost_msg_node *node, *n;
945
946 spin_lock(&d->iotlb_lock);
947
948 list_for_each_entry_safe(node, n, &d->pending_list, node) {
949 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
950 if (msg->iova <= vq_msg->iova &&
951 msg->iova + msg->size - 1 > vq_msg->iova &&
952 vq_msg->type == VHOST_IOTLB_MISS) {
953 vhost_poll_queue(&node->vq->poll);
954 list_del(&node->node);
955 kfree(node);
956 }
957 }
958
959 spin_unlock(&d->iotlb_lock);
960 }
961
962 static int umem_access_ok(u64 uaddr, u64 size, int access)
963 {
964 unsigned long a = uaddr;
965
966 /* Make sure 64 bit math will not overflow. */
967 if (vhost_overflow(uaddr, size))
968 return -EFAULT;
969
970 if ((access & VHOST_ACCESS_RO) &&
971 !access_ok(VERIFY_READ, (void __user *)a, size))
972 return -EFAULT;
973 if ((access & VHOST_ACCESS_WO) &&
974 !access_ok(VERIFY_WRITE, (void __user *)a, size))
975 return -EFAULT;
976 return 0;
977 }
978
979 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
980 struct vhost_iotlb_msg *msg)
981 {
982 int ret = 0;
983
984 vhost_dev_lock_vqs(dev);
985 switch (msg->type) {
986 case VHOST_IOTLB_UPDATE:
987 if (!dev->iotlb) {
988 ret = -EFAULT;
989 break;
990 }
991 if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
992 ret = -EFAULT;
993 break;
994 }
995 vhost_vq_meta_reset(dev);
996 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
997 msg->iova + msg->size - 1,
998 msg->uaddr, msg->perm)) {
999 ret = -ENOMEM;
1000 break;
1001 }
1002 vhost_iotlb_notify_vq(dev, msg);
1003 break;
1004 case VHOST_IOTLB_INVALIDATE:
1005 if (!dev->iotlb) {
1006 ret = -EFAULT;
1007 break;
1008 }
1009 vhost_vq_meta_reset(dev);
1010 vhost_del_umem_range(dev->iotlb, msg->iova,
1011 msg->iova + msg->size - 1);
1012 break;
1013 default:
1014 ret = -EINVAL;
1015 break;
1016 }
1017
1018 vhost_dev_unlock_vqs(dev);
1019 return ret;
1020 }
1021 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1022 struct iov_iter *from)
1023 {
1024 struct vhost_msg_node node;
1025 unsigned size = sizeof(struct vhost_msg);
1026 size_t ret;
1027 int err;
1028
1029 if (iov_iter_count(from) < size)
1030 return 0;
1031 ret = copy_from_iter(&node.msg, size, from);
1032 if (ret != size)
1033 goto done;
1034
1035 switch (node.msg.type) {
1036 case VHOST_IOTLB_MSG:
1037 err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
1038 if (err)
1039 ret = err;
1040 break;
1041 default:
1042 ret = -EINVAL;
1043 break;
1044 }
1045
1046 done:
1047 return ret;
1048 }
1049 EXPORT_SYMBOL(vhost_chr_write_iter);
1050
1051 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1052 poll_table *wait)
1053 {
1054 __poll_t mask = 0;
1055
1056 poll_wait(file, &dev->wait, wait);
1057
1058 if (!list_empty(&dev->read_list))
1059 mask |= EPOLLIN | EPOLLRDNORM;
1060
1061 return mask;
1062 }
1063 EXPORT_SYMBOL(vhost_chr_poll);
1064
1065 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1066 int noblock)
1067 {
1068 DEFINE_WAIT(wait);
1069 struct vhost_msg_node *node;
1070 ssize_t ret = 0;
1071 unsigned size = sizeof(struct vhost_msg);
1072
1073 if (iov_iter_count(to) < size)
1074 return 0;
1075
1076 while (1) {
1077 if (!noblock)
1078 prepare_to_wait(&dev->wait, &wait,
1079 TASK_INTERRUPTIBLE);
1080
1081 node = vhost_dequeue_msg(dev, &dev->read_list);
1082 if (node)
1083 break;
1084 if (noblock) {
1085 ret = -EAGAIN;
1086 break;
1087 }
1088 if (signal_pending(current)) {
1089 ret = -ERESTARTSYS;
1090 break;
1091 }
1092 if (!dev->iotlb) {
1093 ret = -EBADFD;
1094 break;
1095 }
1096
1097 schedule();
1098 }
1099
1100 if (!noblock)
1101 finish_wait(&dev->wait, &wait);
1102
1103 if (node) {
1104 ret = copy_to_iter(&node->msg, size, to);
1105
1106 if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {
1107 kfree(node);
1108 return ret;
1109 }
1110
1111 vhost_enqueue_msg(dev, &dev->pending_list, node);
1112 }
1113
1114 return ret;
1115 }
1116 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1117
1118 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1119 {
1120 struct vhost_dev *dev = vq->dev;
1121 struct vhost_msg_node *node;
1122 struct vhost_iotlb_msg *msg;
1123
1124 node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
1125 if (!node)
1126 return -ENOMEM;
1127
1128 msg = &node->msg.iotlb;
1129 msg->type = VHOST_IOTLB_MISS;
1130 msg->iova = iova;
1131 msg->perm = access;
1132
1133 vhost_enqueue_msg(dev, &dev->read_list, node);
1134
1135 return 0;
1136 }
1137
1138 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1139 struct vring_desc __user *desc,
1140 struct vring_avail __user *avail,
1141 struct vring_used __user *used)
1142
1143 {
1144 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1145
1146 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
1147 access_ok(VERIFY_READ, avail,
1148 sizeof *avail + num * sizeof *avail->ring + s) &&
1149 access_ok(VERIFY_WRITE, used,
1150 sizeof *used + num * sizeof *used->ring + s);
1151 }
1152
1153 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1154 const struct vhost_umem_node *node,
1155 int type)
1156 {
1157 int access = (type == VHOST_ADDR_USED) ?
1158 VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1159
1160 if (likely(node->perm & access))
1161 vq->meta_iotlb[type] = node;
1162 }
1163
1164 static int iotlb_access_ok(struct vhost_virtqueue *vq,
1165 int access, u64 addr, u64 len, int type)
1166 {
1167 const struct vhost_umem_node *node;
1168 struct vhost_umem *umem = vq->iotlb;
1169 u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1170
1171 if (vhost_vq_meta_fetch(vq, addr, len, type))
1172 return true;
1173
1174 while (len > s) {
1175 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1176 addr,
1177 last);
1178 if (node == NULL || node->start > addr) {
1179 vhost_iotlb_miss(vq, addr, access);
1180 return false;
1181 } else if (!(node->perm & access)) {
1182 /* Report the possible access violation by
1183 * request another translation from userspace.
1184 */
1185 return false;
1186 }
1187
1188 size = node->size - addr + node->start;
1189
1190 if (orig_addr == addr && size >= len)
1191 vhost_vq_meta_update(vq, node, type);
1192
1193 s += size;
1194 addr += size;
1195 }
1196
1197 return true;
1198 }
1199
1200 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1201 {
1202 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1203 unsigned int num = vq->num;
1204
1205 if (!vq->iotlb)
1206 return 1;
1207
1208 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1209 num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
1210 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1211 sizeof *vq->avail +
1212 num * sizeof(*vq->avail->ring) + s,
1213 VHOST_ADDR_AVAIL) &&
1214 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1215 sizeof *vq->used +
1216 num * sizeof(*vq->used->ring) + s,
1217 VHOST_ADDR_USED);
1218 }
1219 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1220
1221 /* Can we log writes? */
1222 /* Caller should have device mutex but not vq mutex */
1223 int vhost_log_access_ok(struct vhost_dev *dev)
1224 {
1225 return memory_access_ok(dev, dev->umem, 1);
1226 }
1227 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1228
1229 /* Verify access for write logging. */
1230 /* Caller should have vq mutex and device mutex */
1231 static int vq_log_access_ok(struct vhost_virtqueue *vq,
1232 void __user *log_base)
1233 {
1234 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1235
1236 return vq_memory_access_ok(log_base, vq->umem,
1237 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1238 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1239 sizeof *vq->used +
1240 vq->num * sizeof *vq->used->ring + s));
1241 }
1242
1243 /* Can we start vq? */
1244 /* Caller should have vq mutex and device mutex */
1245 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
1246 {
1247 int ret = vq_log_access_ok(vq, vq->log_base);
1248
1249 if (ret || vq->iotlb)
1250 return ret;
1251
1252 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1253 }
1254 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1255
1256 static struct vhost_umem *vhost_umem_alloc(void)
1257 {
1258 struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1259
1260 if (!umem)
1261 return NULL;
1262
1263 umem->umem_tree = RB_ROOT_CACHED;
1264 umem->numem = 0;
1265 INIT_LIST_HEAD(&umem->umem_list);
1266
1267 return umem;
1268 }
1269
1270 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1271 {
1272 struct vhost_memory mem, *newmem;
1273 struct vhost_memory_region *region;
1274 struct vhost_umem *newumem, *oldumem;
1275 unsigned long size = offsetof(struct vhost_memory, regions);
1276 int i;
1277
1278 if (copy_from_user(&mem, m, size))
1279 return -EFAULT;
1280 if (mem.padding)
1281 return -EOPNOTSUPP;
1282 if (mem.nregions > max_mem_regions)
1283 return -E2BIG;
1284 newmem = kvzalloc(size + mem.nregions * sizeof(*m->regions), GFP_KERNEL);
1285 if (!newmem)
1286 return -ENOMEM;
1287
1288 memcpy(newmem, &mem, size);
1289 if (copy_from_user(newmem->regions, m->regions,
1290 mem.nregions * sizeof *m->regions)) {
1291 kvfree(newmem);
1292 return -EFAULT;
1293 }
1294
1295 newumem = vhost_umem_alloc();
1296 if (!newumem) {
1297 kvfree(newmem);
1298 return -ENOMEM;
1299 }
1300
1301 for (region = newmem->regions;
1302 region < newmem->regions + mem.nregions;
1303 region++) {
1304 if (vhost_new_umem_range(newumem,
1305 region->guest_phys_addr,
1306 region->memory_size,
1307 region->guest_phys_addr +
1308 region->memory_size - 1,
1309 region->userspace_addr,
1310 VHOST_ACCESS_RW))
1311 goto err;
1312 }
1313
1314 if (!memory_access_ok(d, newumem, 0))
1315 goto err;
1316
1317 oldumem = d->umem;
1318 d->umem = newumem;
1319
1320 /* All memory accesses are done under some VQ mutex. */
1321 for (i = 0; i < d->nvqs; ++i) {
1322 mutex_lock(&d->vqs[i]->mutex);
1323 d->vqs[i]->umem = newumem;
1324 mutex_unlock(&d->vqs[i]->mutex);
1325 }
1326
1327 kvfree(newmem);
1328 vhost_umem_clean(oldumem);
1329 return 0;
1330
1331 err:
1332 vhost_umem_clean(newumem);
1333 kvfree(newmem);
1334 return -EFAULT;
1335 }
1336
1337 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1338 {
1339 struct file *eventfp, *filep = NULL;
1340 bool pollstart = false, pollstop = false;
1341 struct eventfd_ctx *ctx = NULL;
1342 u32 __user *idxp = argp;
1343 struct vhost_virtqueue *vq;
1344 struct vhost_vring_state s;
1345 struct vhost_vring_file f;
1346 struct vhost_vring_addr a;
1347 u32 idx;
1348 long r;
1349
1350 r = get_user(idx, idxp);
1351 if (r < 0)
1352 return r;
1353 if (idx >= d->nvqs)
1354 return -ENOBUFS;
1355
1356 vq = d->vqs[idx];
1357
1358 mutex_lock(&vq->mutex);
1359
1360 switch (ioctl) {
1361 case VHOST_SET_VRING_NUM:
1362 /* Resizing ring with an active backend?
1363 * You don't want to do that. */
1364 if (vq->private_data) {
1365 r = -EBUSY;
1366 break;
1367 }
1368 if (copy_from_user(&s, argp, sizeof s)) {
1369 r = -EFAULT;
1370 break;
1371 }
1372 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1373 r = -EINVAL;
1374 break;
1375 }
1376 vq->num = s.num;
1377 break;
1378 case VHOST_SET_VRING_BASE:
1379 /* Moving base with an active backend?
1380 * You don't want to do that. */
1381 if (vq->private_data) {
1382 r = -EBUSY;
1383 break;
1384 }
1385 if (copy_from_user(&s, argp, sizeof s)) {
1386 r = -EFAULT;
1387 break;
1388 }
1389 if (s.num > 0xffff) {
1390 r = -EINVAL;
1391 break;
1392 }
1393 vq->last_avail_idx = s.num;
1394 /* Forget the cached index value. */
1395 vq->avail_idx = vq->last_avail_idx;
1396 break;
1397 case VHOST_GET_VRING_BASE:
1398 s.index = idx;
1399 s.num = vq->last_avail_idx;
1400 if (copy_to_user(argp, &s, sizeof s))
1401 r = -EFAULT;
1402 break;
1403 case VHOST_SET_VRING_ADDR:
1404 if (copy_from_user(&a, argp, sizeof a)) {
1405 r = -EFAULT;
1406 break;
1407 }
1408 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1409 r = -EOPNOTSUPP;
1410 break;
1411 }
1412 /* For 32bit, verify that the top 32bits of the user
1413 data are set to zero. */
1414 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1415 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1416 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1417 r = -EFAULT;
1418 break;
1419 }
1420
1421 /* Make sure it's safe to cast pointers to vring types. */
1422 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1423 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1424 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1425 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1426 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1427 r = -EINVAL;
1428 break;
1429 }
1430
1431 /* We only verify access here if backend is configured.
1432 * If it is not, we don't as size might not have been setup.
1433 * We will verify when backend is configured. */
1434 if (vq->private_data) {
1435 if (!vq_access_ok(vq, vq->num,
1436 (void __user *)(unsigned long)a.desc_user_addr,
1437 (void __user *)(unsigned long)a.avail_user_addr,
1438 (void __user *)(unsigned long)a.used_user_addr)) {
1439 r = -EINVAL;
1440 break;
1441 }
1442
1443 /* Also validate log access for used ring if enabled. */
1444 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1445 !log_access_ok(vq->log_base, a.log_guest_addr,
1446 sizeof *vq->used +
1447 vq->num * sizeof *vq->used->ring)) {
1448 r = -EINVAL;
1449 break;
1450 }
1451 }
1452
1453 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1454 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1455 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1456 vq->log_addr = a.log_guest_addr;
1457 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1458 break;
1459 case VHOST_SET_VRING_KICK:
1460 if (copy_from_user(&f, argp, sizeof f)) {
1461 r = -EFAULT;
1462 break;
1463 }
1464 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1465 if (IS_ERR(eventfp)) {
1466 r = PTR_ERR(eventfp);
1467 break;
1468 }
1469 if (eventfp != vq->kick) {
1470 pollstop = (filep = vq->kick) != NULL;
1471 pollstart = (vq->kick = eventfp) != NULL;
1472 } else
1473 filep = eventfp;
1474 break;
1475 case VHOST_SET_VRING_CALL:
1476 if (copy_from_user(&f, argp, sizeof f)) {
1477 r = -EFAULT;
1478 break;
1479 }
1480 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1481 if (IS_ERR(ctx)) {
1482 r = PTR_ERR(ctx);
1483 break;
1484 }
1485 swap(ctx, vq->call_ctx);
1486 break;
1487 case VHOST_SET_VRING_ERR:
1488 if (copy_from_user(&f, argp, sizeof f)) {
1489 r = -EFAULT;
1490 break;
1491 }
1492 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1493 if (IS_ERR(ctx)) {
1494 r = PTR_ERR(ctx);
1495 break;
1496 }
1497 swap(ctx, vq->error_ctx);
1498 break;
1499 case VHOST_SET_VRING_ENDIAN:
1500 r = vhost_set_vring_endian(vq, argp);
1501 break;
1502 case VHOST_GET_VRING_ENDIAN:
1503 r = vhost_get_vring_endian(vq, idx, argp);
1504 break;
1505 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1506 if (copy_from_user(&s, argp, sizeof(s))) {
1507 r = -EFAULT;
1508 break;
1509 }
1510 vq->busyloop_timeout = s.num;
1511 break;
1512 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1513 s.index = idx;
1514 s.num = vq->busyloop_timeout;
1515 if (copy_to_user(argp, &s, sizeof(s)))
1516 r = -EFAULT;
1517 break;
1518 default:
1519 r = -ENOIOCTLCMD;
1520 }
1521
1522 if (pollstop && vq->handle_kick)
1523 vhost_poll_stop(&vq->poll);
1524
1525 if (!IS_ERR_OR_NULL(ctx))
1526 eventfd_ctx_put(ctx);
1527 if (filep)
1528 fput(filep);
1529
1530 if (pollstart && vq->handle_kick)
1531 r = vhost_poll_start(&vq->poll, vq->kick);
1532
1533 mutex_unlock(&vq->mutex);
1534
1535 if (pollstop && vq->handle_kick)
1536 vhost_poll_flush(&vq->poll);
1537 return r;
1538 }
1539 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1540
1541 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1542 {
1543 struct vhost_umem *niotlb, *oiotlb;
1544 int i;
1545
1546 niotlb = vhost_umem_alloc();
1547 if (!niotlb)
1548 return -ENOMEM;
1549
1550 oiotlb = d->iotlb;
1551 d->iotlb = niotlb;
1552
1553 for (i = 0; i < d->nvqs; ++i) {
1554 mutex_lock(&d->vqs[i]->mutex);
1555 d->vqs[i]->iotlb = niotlb;
1556 mutex_unlock(&d->vqs[i]->mutex);
1557 }
1558
1559 vhost_umem_clean(oiotlb);
1560
1561 return 0;
1562 }
1563 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1564
1565 /* Caller must have device mutex */
1566 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1567 {
1568 struct eventfd_ctx *ctx;
1569 u64 p;
1570 long r;
1571 int i, fd;
1572
1573 /* If you are not the owner, you can become one */
1574 if (ioctl == VHOST_SET_OWNER) {
1575 r = vhost_dev_set_owner(d);
1576 goto done;
1577 }
1578
1579 /* You must be the owner to do anything else */
1580 r = vhost_dev_check_owner(d);
1581 if (r)
1582 goto done;
1583
1584 switch (ioctl) {
1585 case VHOST_SET_MEM_TABLE:
1586 r = vhost_set_memory(d, argp);
1587 break;
1588 case VHOST_SET_LOG_BASE:
1589 if (copy_from_user(&p, argp, sizeof p)) {
1590 r = -EFAULT;
1591 break;
1592 }
1593 if ((u64)(unsigned long)p != p) {
1594 r = -EFAULT;
1595 break;
1596 }
1597 for (i = 0; i < d->nvqs; ++i) {
1598 struct vhost_virtqueue *vq;
1599 void __user *base = (void __user *)(unsigned long)p;
1600 vq = d->vqs[i];
1601 mutex_lock(&vq->mutex);
1602 /* If ring is inactive, will check when it's enabled. */
1603 if (vq->private_data && !vq_log_access_ok(vq, base))
1604 r = -EFAULT;
1605 else
1606 vq->log_base = base;
1607 mutex_unlock(&vq->mutex);
1608 }
1609 break;
1610 case VHOST_SET_LOG_FD:
1611 r = get_user(fd, (int __user *)argp);
1612 if (r < 0)
1613 break;
1614 ctx = fd == -1 ? NULL : eventfd_ctx_fdget(fd);
1615 if (IS_ERR(ctx)) {
1616 r = PTR_ERR(ctx);
1617 break;
1618 }
1619 swap(ctx, d->log_ctx);
1620 for (i = 0; i < d->nvqs; ++i) {
1621 mutex_lock(&d->vqs[i]->mutex);
1622 d->vqs[i]->log_ctx = d->log_ctx;
1623 mutex_unlock(&d->vqs[i]->mutex);
1624 }
1625 if (ctx)
1626 eventfd_ctx_put(ctx);
1627 break;
1628 default:
1629 r = -ENOIOCTLCMD;
1630 break;
1631 }
1632 done:
1633 return r;
1634 }
1635 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1636
1637 /* TODO: This is really inefficient. We need something like get_user()
1638 * (instruction directly accesses the data, with an exception table entry
1639 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1640 */
1641 static int set_bit_to_user(int nr, void __user *addr)
1642 {
1643 unsigned long log = (unsigned long)addr;
1644 struct page *page;
1645 void *base;
1646 int bit = nr + (log % PAGE_SIZE) * 8;
1647 int r;
1648
1649 r = get_user_pages_fast(log, 1, 1, &page);
1650 if (r < 0)
1651 return r;
1652 BUG_ON(r != 1);
1653 base = kmap_atomic(page);
1654 set_bit(bit, base);
1655 kunmap_atomic(base);
1656 set_page_dirty_lock(page);
1657 put_page(page);
1658 return 0;
1659 }
1660
1661 static int log_write(void __user *log_base,
1662 u64 write_address, u64 write_length)
1663 {
1664 u64 write_page = write_address / VHOST_PAGE_SIZE;
1665 int r;
1666
1667 if (!write_length)
1668 return 0;
1669 write_length += write_address % VHOST_PAGE_SIZE;
1670 for (;;) {
1671 u64 base = (u64)(unsigned long)log_base;
1672 u64 log = base + write_page / 8;
1673 int bit = write_page % 8;
1674 if ((u64)(unsigned long)log != log)
1675 return -EFAULT;
1676 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1677 if (r < 0)
1678 return r;
1679 if (write_length <= VHOST_PAGE_SIZE)
1680 break;
1681 write_length -= VHOST_PAGE_SIZE;
1682 write_page += 1;
1683 }
1684 return r;
1685 }
1686
1687 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1688 unsigned int log_num, u64 len)
1689 {
1690 int i, r;
1691
1692 /* Make sure data written is seen before log. */
1693 smp_wmb();
1694 for (i = 0; i < log_num; ++i) {
1695 u64 l = min(log[i].len, len);
1696 r = log_write(vq->log_base, log[i].addr, l);
1697 if (r < 0)
1698 return r;
1699 len -= l;
1700 if (!len) {
1701 if (vq->log_ctx)
1702 eventfd_signal(vq->log_ctx, 1);
1703 return 0;
1704 }
1705 }
1706 /* Length written exceeds what we have stored. This is a bug. */
1707 BUG();
1708 return 0;
1709 }
1710 EXPORT_SYMBOL_GPL(vhost_log_write);
1711
1712 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1713 {
1714 void __user *used;
1715 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1716 &vq->used->flags) < 0)
1717 return -EFAULT;
1718 if (unlikely(vq->log_used)) {
1719 /* Make sure the flag is seen before log. */
1720 smp_wmb();
1721 /* Log used flag write. */
1722 used = &vq->used->flags;
1723 log_write(vq->log_base, vq->log_addr +
1724 (used - (void __user *)vq->used),
1725 sizeof vq->used->flags);
1726 if (vq->log_ctx)
1727 eventfd_signal(vq->log_ctx, 1);
1728 }
1729 return 0;
1730 }
1731
1732 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1733 {
1734 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1735 vhost_avail_event(vq)))
1736 return -EFAULT;
1737 if (unlikely(vq->log_used)) {
1738 void __user *used;
1739 /* Make sure the event is seen before log. */
1740 smp_wmb();
1741 /* Log avail event write */
1742 used = vhost_avail_event(vq);
1743 log_write(vq->log_base, vq->log_addr +
1744 (used - (void __user *)vq->used),
1745 sizeof *vhost_avail_event(vq));
1746 if (vq->log_ctx)
1747 eventfd_signal(vq->log_ctx, 1);
1748 }
1749 return 0;
1750 }
1751
1752 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1753 {
1754 __virtio16 last_used_idx;
1755 int r;
1756 bool is_le = vq->is_le;
1757
1758 if (!vq->private_data)
1759 return 0;
1760
1761 vhost_init_is_le(vq);
1762
1763 r = vhost_update_used_flags(vq);
1764 if (r)
1765 goto err;
1766 vq->signalled_used_valid = false;
1767 if (!vq->iotlb &&
1768 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1769 r = -EFAULT;
1770 goto err;
1771 }
1772 r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
1773 if (r) {
1774 vq_err(vq, "Can't access used idx at %p\n",
1775 &vq->used->idx);
1776 goto err;
1777 }
1778 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1779 return 0;
1780
1781 err:
1782 vq->is_le = is_le;
1783 return r;
1784 }
1785 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1786
1787 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1788 struct iovec iov[], int iov_size, int access)
1789 {
1790 const struct vhost_umem_node *node;
1791 struct vhost_dev *dev = vq->dev;
1792 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1793 struct iovec *_iov;
1794 u64 s = 0;
1795 int ret = 0;
1796
1797 while ((u64)len > s) {
1798 u64 size;
1799 if (unlikely(ret >= iov_size)) {
1800 ret = -ENOBUFS;
1801 break;
1802 }
1803
1804 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1805 addr, addr + len - 1);
1806 if (node == NULL || node->start > addr) {
1807 if (umem != dev->iotlb) {
1808 ret = -EFAULT;
1809 break;
1810 }
1811 ret = -EAGAIN;
1812 break;
1813 } else if (!(node->perm & access)) {
1814 ret = -EPERM;
1815 break;
1816 }
1817
1818 _iov = iov + ret;
1819 size = node->size - addr + node->start;
1820 _iov->iov_len = min((u64)len - s, size);
1821 _iov->iov_base = (void __user *)(unsigned long)
1822 (node->userspace_addr + addr - node->start);
1823 s += size;
1824 addr += size;
1825 ++ret;
1826 }
1827
1828 if (ret == -EAGAIN)
1829 vhost_iotlb_miss(vq, addr, access);
1830 return ret;
1831 }
1832
1833 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1834 * function returns the next descriptor in the chain,
1835 * or -1U if we're at the end. */
1836 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1837 {
1838 unsigned int next;
1839
1840 /* If this descriptor says it doesn't chain, we're done. */
1841 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1842 return -1U;
1843
1844 /* Check they're not leading us off end of descriptors. */
1845 next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
1846 return next;
1847 }
1848
1849 static int get_indirect(struct vhost_virtqueue *vq,
1850 struct iovec iov[], unsigned int iov_size,
1851 unsigned int *out_num, unsigned int *in_num,
1852 struct vhost_log *log, unsigned int *log_num,
1853 struct vring_desc *indirect)
1854 {
1855 struct vring_desc desc;
1856 unsigned int i = 0, count, found = 0;
1857 u32 len = vhost32_to_cpu(vq, indirect->len);
1858 struct iov_iter from;
1859 int ret, access;
1860
1861 /* Sanity check */
1862 if (unlikely(len % sizeof desc)) {
1863 vq_err(vq, "Invalid length in indirect descriptor: "
1864 "len 0x%llx not multiple of 0x%zx\n",
1865 (unsigned long long)len,
1866 sizeof desc);
1867 return -EINVAL;
1868 }
1869
1870 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1871 UIO_MAXIOV, VHOST_ACCESS_RO);
1872 if (unlikely(ret < 0)) {
1873 if (ret != -EAGAIN)
1874 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1875 return ret;
1876 }
1877 iov_iter_init(&from, READ, vq->indirect, ret, len);
1878
1879 /* We will use the result as an address to read from, so most
1880 * architectures only need a compiler barrier here. */
1881 read_barrier_depends();
1882
1883 count = len / sizeof desc;
1884 /* Buffers are chained via a 16 bit next field, so
1885 * we can have at most 2^16 of these. */
1886 if (unlikely(count > USHRT_MAX + 1)) {
1887 vq_err(vq, "Indirect buffer length too big: %d\n",
1888 indirect->len);
1889 return -E2BIG;
1890 }
1891
1892 do {
1893 unsigned iov_count = *in_num + *out_num;
1894 if (unlikely(++found > count)) {
1895 vq_err(vq, "Loop detected: last one at %u "
1896 "indirect size %u\n",
1897 i, count);
1898 return -EINVAL;
1899 }
1900 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1901 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1902 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1903 return -EINVAL;
1904 }
1905 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1906 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1907 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1908 return -EINVAL;
1909 }
1910
1911 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1912 access = VHOST_ACCESS_WO;
1913 else
1914 access = VHOST_ACCESS_RO;
1915
1916 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1917 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1918 iov_size - iov_count, access);
1919 if (unlikely(ret < 0)) {
1920 if (ret != -EAGAIN)
1921 vq_err(vq, "Translation failure %d indirect idx %d\n",
1922 ret, i);
1923 return ret;
1924 }
1925 /* If this is an input descriptor, increment that count. */
1926 if (access == VHOST_ACCESS_WO) {
1927 *in_num += ret;
1928 if (unlikely(log)) {
1929 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1930 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1931 ++*log_num;
1932 }
1933 } else {
1934 /* If it's an output descriptor, they're all supposed
1935 * to come before any input descriptors. */
1936 if (unlikely(*in_num)) {
1937 vq_err(vq, "Indirect descriptor "
1938 "has out after in: idx %d\n", i);
1939 return -EINVAL;
1940 }
1941 *out_num += ret;
1942 }
1943 } while ((i = next_desc(vq, &desc)) != -1);
1944 return 0;
1945 }
1946
1947 /* This looks in the virtqueue and for the first available buffer, and converts
1948 * it to an iovec for convenient access. Since descriptors consist of some
1949 * number of output then some number of input descriptors, it's actually two
1950 * iovecs, but we pack them into one and note how many of each there were.
1951 *
1952 * This function returns the descriptor number found, or vq->num (which is
1953 * never a valid descriptor number) if none was found. A negative code is
1954 * returned on error. */
1955 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1956 struct iovec iov[], unsigned int iov_size,
1957 unsigned int *out_num, unsigned int *in_num,
1958 struct vhost_log *log, unsigned int *log_num)
1959 {
1960 struct vring_desc desc;
1961 unsigned int i, head, found = 0;
1962 u16 last_avail_idx;
1963 __virtio16 avail_idx;
1964 __virtio16 ring_head;
1965 int ret, access;
1966
1967 /* Check it isn't doing very strange things with descriptor numbers. */
1968 last_avail_idx = vq->last_avail_idx;
1969
1970 if (vq->avail_idx == vq->last_avail_idx) {
1971 if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
1972 vq_err(vq, "Failed to access avail idx at %p\n",
1973 &vq->avail->idx);
1974 return -EFAULT;
1975 }
1976 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1977
1978 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1979 vq_err(vq, "Guest moved used index from %u to %u",
1980 last_avail_idx, vq->avail_idx);
1981 return -EFAULT;
1982 }
1983
1984 /* If there's nothing new since last we looked, return
1985 * invalid.
1986 */
1987 if (vq->avail_idx == last_avail_idx)
1988 return vq->num;
1989
1990 /* Only get avail ring entries after they have been
1991 * exposed by guest.
1992 */
1993 smp_rmb();
1994 }
1995
1996 /* Grab the next descriptor number they're advertising, and increment
1997 * the index we've seen. */
1998 if (unlikely(vhost_get_avail(vq, ring_head,
1999 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
2000 vq_err(vq, "Failed to read head: idx %d address %p\n",
2001 last_avail_idx,
2002 &vq->avail->ring[last_avail_idx % vq->num]);
2003 return -EFAULT;
2004 }
2005
2006 head = vhost16_to_cpu(vq, ring_head);
2007
2008 /* If their number is silly, that's an error. */
2009 if (unlikely(head >= vq->num)) {
2010 vq_err(vq, "Guest says index %u > %u is available",
2011 head, vq->num);
2012 return -EINVAL;
2013 }
2014
2015 /* When we start there are none of either input nor output. */
2016 *out_num = *in_num = 0;
2017 if (unlikely(log))
2018 *log_num = 0;
2019
2020 i = head;
2021 do {
2022 unsigned iov_count = *in_num + *out_num;
2023 if (unlikely(i >= vq->num)) {
2024 vq_err(vq, "Desc index is %u > %u, head = %u",
2025 i, vq->num, head);
2026 return -EINVAL;
2027 }
2028 if (unlikely(++found > vq->num)) {
2029 vq_err(vq, "Loop detected: last one at %u "
2030 "vq size %u head %u\n",
2031 i, vq->num, head);
2032 return -EINVAL;
2033 }
2034 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
2035 sizeof desc);
2036 if (unlikely(ret)) {
2037 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2038 i, vq->desc + i);
2039 return -EFAULT;
2040 }
2041 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2042 ret = get_indirect(vq, iov, iov_size,
2043 out_num, in_num,
2044 log, log_num, &desc);
2045 if (unlikely(ret < 0)) {
2046 if (ret != -EAGAIN)
2047 vq_err(vq, "Failure detected "
2048 "in indirect descriptor at idx %d\n", i);
2049 return ret;
2050 }
2051 continue;
2052 }
2053
2054 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2055 access = VHOST_ACCESS_WO;
2056 else
2057 access = VHOST_ACCESS_RO;
2058 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2059 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2060 iov_size - iov_count, access);
2061 if (unlikely(ret < 0)) {
2062 if (ret != -EAGAIN)
2063 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2064 ret, i);
2065 return ret;
2066 }
2067 if (access == VHOST_ACCESS_WO) {
2068 /* If this is an input descriptor,
2069 * increment that count. */
2070 *in_num += ret;
2071 if (unlikely(log)) {
2072 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2073 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2074 ++*log_num;
2075 }
2076 } else {
2077 /* If it's an output descriptor, they're all supposed
2078 * to come before any input descriptors. */
2079 if (unlikely(*in_num)) {
2080 vq_err(vq, "Descriptor has out after in: "
2081 "idx %d\n", i);
2082 return -EINVAL;
2083 }
2084 *out_num += ret;
2085 }
2086 } while ((i = next_desc(vq, &desc)) != -1);
2087
2088 /* On success, increment avail index. */
2089 vq->last_avail_idx++;
2090
2091 /* Assume notifications from guest are disabled at this point,
2092 * if they aren't we would need to update avail_event index. */
2093 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2094 return head;
2095 }
2096 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2097
2098 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2099 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2100 {
2101 vq->last_avail_idx -= n;
2102 }
2103 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2104
2105 /* After we've used one of their buffers, we tell them about it. We'll then
2106 * want to notify the guest, using eventfd. */
2107 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2108 {
2109 struct vring_used_elem heads = {
2110 cpu_to_vhost32(vq, head),
2111 cpu_to_vhost32(vq, len)
2112 };
2113
2114 return vhost_add_used_n(vq, &heads, 1);
2115 }
2116 EXPORT_SYMBOL_GPL(vhost_add_used);
2117
2118 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2119 struct vring_used_elem *heads,
2120 unsigned count)
2121 {
2122 struct vring_used_elem __user *used;
2123 u16 old, new;
2124 int start;
2125
2126 start = vq->last_used_idx & (vq->num - 1);
2127 used = vq->used->ring + start;
2128 if (count == 1) {
2129 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2130 vq_err(vq, "Failed to write used id");
2131 return -EFAULT;
2132 }
2133 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2134 vq_err(vq, "Failed to write used len");
2135 return -EFAULT;
2136 }
2137 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2138 vq_err(vq, "Failed to write used");
2139 return -EFAULT;
2140 }
2141 if (unlikely(vq->log_used)) {
2142 /* Make sure data is seen before log. */
2143 smp_wmb();
2144 /* Log used ring entry write. */
2145 log_write(vq->log_base,
2146 vq->log_addr +
2147 ((void __user *)used - (void __user *)vq->used),
2148 count * sizeof *used);
2149 }
2150 old = vq->last_used_idx;
2151 new = (vq->last_used_idx += count);
2152 /* If the driver never bothers to signal in a very long while,
2153 * used index might wrap around. If that happens, invalidate
2154 * signalled_used index we stored. TODO: make sure driver
2155 * signals at least once in 2^16 and remove this. */
2156 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2157 vq->signalled_used_valid = false;
2158 return 0;
2159 }
2160
2161 /* After we've used one of their buffers, we tell them about it. We'll then
2162 * want to notify the guest, using eventfd. */
2163 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2164 unsigned count)
2165 {
2166 int start, n, r;
2167
2168 start = vq->last_used_idx & (vq->num - 1);
2169 n = vq->num - start;
2170 if (n < count) {
2171 r = __vhost_add_used_n(vq, heads, n);
2172 if (r < 0)
2173 return r;
2174 heads += n;
2175 count -= n;
2176 }
2177 r = __vhost_add_used_n(vq, heads, count);
2178
2179 /* Make sure buffer is written before we update index. */
2180 smp_wmb();
2181 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2182 &vq->used->idx)) {
2183 vq_err(vq, "Failed to increment used idx");
2184 return -EFAULT;
2185 }
2186 if (unlikely(vq->log_used)) {
2187 /* Log used index update. */
2188 log_write(vq->log_base,
2189 vq->log_addr + offsetof(struct vring_used, idx),
2190 sizeof vq->used->idx);
2191 if (vq->log_ctx)
2192 eventfd_signal(vq->log_ctx, 1);
2193 }
2194 return r;
2195 }
2196 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2197
2198 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2199 {
2200 __u16 old, new;
2201 __virtio16 event;
2202 bool v;
2203 /* Flush out used index updates. This is paired
2204 * with the barrier that the Guest executes when enabling
2205 * interrupts. */
2206 smp_mb();
2207
2208 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2209 unlikely(vq->avail_idx == vq->last_avail_idx))
2210 return true;
2211
2212 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2213 __virtio16 flags;
2214 if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
2215 vq_err(vq, "Failed to get flags");
2216 return true;
2217 }
2218 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2219 }
2220 old = vq->signalled_used;
2221 v = vq->signalled_used_valid;
2222 new = vq->signalled_used = vq->last_used_idx;
2223 vq->signalled_used_valid = true;
2224
2225 if (unlikely(!v))
2226 return true;
2227
2228 if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
2229 vq_err(vq, "Failed to get used event idx");
2230 return true;
2231 }
2232 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2233 }
2234
2235 /* This actually signals the guest, using eventfd. */
2236 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2237 {
2238 /* Signal the Guest tell them we used something up. */
2239 if (vq->call_ctx && vhost_notify(dev, vq))
2240 eventfd_signal(vq->call_ctx, 1);
2241 }
2242 EXPORT_SYMBOL_GPL(vhost_signal);
2243
2244 /* And here's the combo meal deal. Supersize me! */
2245 void vhost_add_used_and_signal(struct vhost_dev *dev,
2246 struct vhost_virtqueue *vq,
2247 unsigned int head, int len)
2248 {
2249 vhost_add_used(vq, head, len);
2250 vhost_signal(dev, vq);
2251 }
2252 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2253
2254 /* multi-buffer version of vhost_add_used_and_signal */
2255 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2256 struct vhost_virtqueue *vq,
2257 struct vring_used_elem *heads, unsigned count)
2258 {
2259 vhost_add_used_n(vq, heads, count);
2260 vhost_signal(dev, vq);
2261 }
2262 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2263
2264 /* return true if we're sure that avaiable ring is empty */
2265 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2266 {
2267 __virtio16 avail_idx;
2268 int r;
2269
2270 if (vq->avail_idx != vq->last_avail_idx)
2271 return false;
2272
2273 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2274 if (unlikely(r))
2275 return false;
2276 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2277
2278 return vq->avail_idx == vq->last_avail_idx;
2279 }
2280 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2281
2282 /* OK, now we need to know about added descriptors. */
2283 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2284 {
2285 __virtio16 avail_idx;
2286 int r;
2287
2288 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2289 return false;
2290 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2291 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2292 r = vhost_update_used_flags(vq);
2293 if (r) {
2294 vq_err(vq, "Failed to enable notification at %p: %d\n",
2295 &vq->used->flags, r);
2296 return false;
2297 }
2298 } else {
2299 r = vhost_update_avail_event(vq, vq->avail_idx);
2300 if (r) {
2301 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2302 vhost_avail_event(vq), r);
2303 return false;
2304 }
2305 }
2306 /* They could have slipped one in as we were doing that: make
2307 * sure it's written, then check again. */
2308 smp_mb();
2309 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2310 if (r) {
2311 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2312 &vq->avail->idx, r);
2313 return false;
2314 }
2315
2316 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2317 }
2318 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2319
2320 /* We don't need to be notified again. */
2321 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2322 {
2323 int r;
2324
2325 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2326 return;
2327 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2328 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2329 r = vhost_update_used_flags(vq);
2330 if (r)
2331 vq_err(vq, "Failed to enable notification at %p: %d\n",
2332 &vq->used->flags, r);
2333 }
2334 }
2335 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2336
2337 /* Create a new message. */
2338 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2339 {
2340 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2341 if (!node)
2342 return NULL;
2343 node->vq = vq;
2344 node->msg.type = type;
2345 return node;
2346 }
2347 EXPORT_SYMBOL_GPL(vhost_new_msg);
2348
2349 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2350 struct vhost_msg_node *node)
2351 {
2352 spin_lock(&dev->iotlb_lock);
2353 list_add_tail(&node->node, head);
2354 spin_unlock(&dev->iotlb_lock);
2355
2356 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2357 }
2358 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2359
2360 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2361 struct list_head *head)
2362 {
2363 struct vhost_msg_node *node = NULL;
2364
2365 spin_lock(&dev->iotlb_lock);
2366 if (!list_empty(head)) {
2367 node = list_first_entry(head, struct vhost_msg_node,
2368 node);
2369 list_del(&node->node);
2370 }
2371 spin_unlock(&dev->iotlb_lock);
2372
2373 return node;
2374 }
2375 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2376
2377
2378 static int __init vhost_init(void)
2379 {
2380 return 0;
2381 }
2382
2383 static void __exit vhost_exit(void)
2384 {
2385 }
2386
2387 module_init(vhost_init);
2388 module_exit(vhost_exit);
2389
2390 MODULE_VERSION("0.0.1");
2391 MODULE_LICENSE("GPL v2");
2392 MODULE_AUTHOR("Michael S. Tsirkin");
2393 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
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