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[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 #include <linux/nospec.h>
34
35 #include "vhost.h"
36
37 static ushort max_mem_regions = 64;
38 module_param(max_mem_regions, ushort, 0444);
39 MODULE_PARM_DESC(max_mem_regions,
40 "Maximum number of memory regions in memory map. (default: 64)");
41 static int max_iotlb_entries = 2048;
42 module_param(max_iotlb_entries, int, 0444);
43 MODULE_PARM_DESC(max_iotlb_entries,
44 "Maximum number of iotlb entries. (default: 2048)");
45
46 enum {
47 VHOST_MEMORY_F_LOG = 0x1,
48 };
49
50 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
51 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
52
53 INTERVAL_TREE_DEFINE(struct vhost_umem_node,
54 rb, __u64, __subtree_last,
55 START, LAST, static inline, vhost_umem_interval_tree);
56
57 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
58 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
59 {
60 vq->user_be = !virtio_legacy_is_little_endian();
61 }
62
63 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
64 {
65 vq->user_be = true;
66 }
67
68 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
69 {
70 vq->user_be = false;
71 }
72
73 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
74 {
75 struct vhost_vring_state s;
76
77 if (vq->private_data)
78 return -EBUSY;
79
80 if (copy_from_user(&s, argp, sizeof(s)))
81 return -EFAULT;
82
83 if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
84 s.num != VHOST_VRING_BIG_ENDIAN)
85 return -EINVAL;
86
87 if (s.num == VHOST_VRING_BIG_ENDIAN)
88 vhost_enable_cross_endian_big(vq);
89 else
90 vhost_enable_cross_endian_little(vq);
91
92 return 0;
93 }
94
95 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
96 int __user *argp)
97 {
98 struct vhost_vring_state s = {
99 .index = idx,
100 .num = vq->user_be
101 };
102
103 if (copy_to_user(argp, &s, sizeof(s)))
104 return -EFAULT;
105
106 return 0;
107 }
108
109 static void vhost_init_is_le(struct vhost_virtqueue *vq)
110 {
111 /* Note for legacy virtio: user_be is initialized at reset time
112 * according to the host endianness. If userspace does not set an
113 * explicit endianness, the default behavior is native endian, as
114 * expected by legacy virtio.
115 */
116 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
117 }
118 #else
119 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
120 {
121 }
122
123 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
124 {
125 return -ENOIOCTLCMD;
126 }
127
128 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
129 int __user *argp)
130 {
131 return -ENOIOCTLCMD;
132 }
133
134 static void vhost_init_is_le(struct vhost_virtqueue *vq)
135 {
136 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
137 || virtio_legacy_is_little_endian();
138 }
139 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
140
141 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
142 {
143 vhost_init_is_le(vq);
144 }
145
146 struct vhost_flush_struct {
147 struct vhost_work work;
148 struct completion wait_event;
149 };
150
151 static void vhost_flush_work(struct vhost_work *work)
152 {
153 struct vhost_flush_struct *s;
154
155 s = container_of(work, struct vhost_flush_struct, work);
156 complete(&s->wait_event);
157 }
158
159 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
160 poll_table *pt)
161 {
162 struct vhost_poll *poll;
163
164 poll = container_of(pt, struct vhost_poll, table);
165 poll->wqh = wqh;
166 add_wait_queue(wqh, &poll->wait);
167 }
168
169 static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
170 void *key)
171 {
172 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
173
174 if (!(key_to_poll(key) & poll->mask))
175 return 0;
176
177 vhost_poll_queue(poll);
178 return 0;
179 }
180
181 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
182 {
183 clear_bit(VHOST_WORK_QUEUED, &work->flags);
184 work->fn = fn;
185 }
186 EXPORT_SYMBOL_GPL(vhost_work_init);
187
188 /* Init poll structure */
189 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
190 __poll_t mask, struct vhost_dev *dev)
191 {
192 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
193 init_poll_funcptr(&poll->table, vhost_poll_func);
194 poll->mask = mask;
195 poll->dev = dev;
196 poll->wqh = NULL;
197
198 vhost_work_init(&poll->work, fn);
199 }
200 EXPORT_SYMBOL_GPL(vhost_poll_init);
201
202 /* Start polling a file. We add ourselves to file's wait queue. The caller must
203 * keep a reference to a file until after vhost_poll_stop is called. */
204 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
205 {
206 __poll_t mask;
207 int ret = 0;
208
209 if (poll->wqh)
210 return 0;
211
212 mask = vfs_poll(file, &poll->table);
213 if (mask)
214 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
215 if (mask & EPOLLERR) {
216 vhost_poll_stop(poll);
217 ret = -EINVAL;
218 }
219
220 return ret;
221 }
222 EXPORT_SYMBOL_GPL(vhost_poll_start);
223
224 /* Stop polling a file. After this function returns, it becomes safe to drop the
225 * file reference. You must also flush afterwards. */
226 void vhost_poll_stop(struct vhost_poll *poll)
227 {
228 if (poll->wqh) {
229 remove_wait_queue(poll->wqh, &poll->wait);
230 poll->wqh = NULL;
231 }
232 }
233 EXPORT_SYMBOL_GPL(vhost_poll_stop);
234
235 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
236 {
237 struct vhost_flush_struct flush;
238
239 if (dev->worker) {
240 init_completion(&flush.wait_event);
241 vhost_work_init(&flush.work, vhost_flush_work);
242
243 vhost_work_queue(dev, &flush.work);
244 wait_for_completion(&flush.wait_event);
245 }
246 }
247 EXPORT_SYMBOL_GPL(vhost_work_flush);
248
249 /* Flush any work that has been scheduled. When calling this, don't hold any
250 * locks that are also used by the callback. */
251 void vhost_poll_flush(struct vhost_poll *poll)
252 {
253 vhost_work_flush(poll->dev, &poll->work);
254 }
255 EXPORT_SYMBOL_GPL(vhost_poll_flush);
256
257 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
258 {
259 if (!dev->worker)
260 return;
261
262 if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
263 /* We can only add the work to the list after we're
264 * sure it was not in the list.
265 * test_and_set_bit() implies a memory barrier.
266 */
267 llist_add(&work->node, &dev->work_list);
268 wake_up_process(dev->worker);
269 }
270 }
271 EXPORT_SYMBOL_GPL(vhost_work_queue);
272
273 /* A lockless hint for busy polling code to exit the loop */
274 bool vhost_has_work(struct vhost_dev *dev)
275 {
276 return !llist_empty(&dev->work_list);
277 }
278 EXPORT_SYMBOL_GPL(vhost_has_work);
279
280 void vhost_poll_queue(struct vhost_poll *poll)
281 {
282 vhost_work_queue(poll->dev, &poll->work);
283 }
284 EXPORT_SYMBOL_GPL(vhost_poll_queue);
285
286 static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
287 {
288 int j;
289
290 for (j = 0; j < VHOST_NUM_ADDRS; j++)
291 vq->meta_iotlb[j] = NULL;
292 }
293
294 static void vhost_vq_meta_reset(struct vhost_dev *d)
295 {
296 int i;
297
298 for (i = 0; i < d->nvqs; ++i)
299 __vhost_vq_meta_reset(d->vqs[i]);
300 }
301
302 static void vhost_vq_reset(struct vhost_dev *dev,
303 struct vhost_virtqueue *vq)
304 {
305 vq->num = 1;
306 vq->desc = NULL;
307 vq->avail = NULL;
308 vq->used = NULL;
309 vq->last_avail_idx = 0;
310 vq->avail_idx = 0;
311 vq->last_used_idx = 0;
312 vq->signalled_used = 0;
313 vq->signalled_used_valid = false;
314 vq->used_flags = 0;
315 vq->log_used = false;
316 vq->log_addr = -1ull;
317 vq->private_data = NULL;
318 vq->acked_features = 0;
319 vq->acked_backend_features = 0;
320 vq->log_base = NULL;
321 vq->error_ctx = NULL;
322 vq->kick = NULL;
323 vq->call_ctx = NULL;
324 vq->log_ctx = NULL;
325 vhost_reset_is_le(vq);
326 vhost_disable_cross_endian(vq);
327 vq->busyloop_timeout = 0;
328 vq->umem = NULL;
329 vq->iotlb = NULL;
330 __vhost_vq_meta_reset(vq);
331 }
332
333 static int vhost_worker(void *data)
334 {
335 struct vhost_dev *dev = data;
336 struct vhost_work *work, *work_next;
337 struct llist_node *node;
338 mm_segment_t oldfs = get_fs();
339
340 set_fs(USER_DS);
341 use_mm(dev->mm);
342
343 for (;;) {
344 /* mb paired w/ kthread_stop */
345 set_current_state(TASK_INTERRUPTIBLE);
346
347 if (kthread_should_stop()) {
348 __set_current_state(TASK_RUNNING);
349 break;
350 }
351
352 node = llist_del_all(&dev->work_list);
353 if (!node)
354 schedule();
355
356 node = llist_reverse_order(node);
357 /* make sure flag is seen after deletion */
358 smp_wmb();
359 llist_for_each_entry_safe(work, work_next, node, node) {
360 clear_bit(VHOST_WORK_QUEUED, &work->flags);
361 __set_current_state(TASK_RUNNING);
362 work->fn(work);
363 if (need_resched())
364 schedule();
365 }
366 }
367 unuse_mm(dev->mm);
368 set_fs(oldfs);
369 return 0;
370 }
371
372 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
373 {
374 kfree(vq->indirect);
375 vq->indirect = NULL;
376 kfree(vq->log);
377 vq->log = NULL;
378 kfree(vq->heads);
379 vq->heads = NULL;
380 }
381
382 /* Helper to allocate iovec buffers for all vqs. */
383 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
384 {
385 struct vhost_virtqueue *vq;
386 int i;
387
388 for (i = 0; i < dev->nvqs; ++i) {
389 vq = dev->vqs[i];
390 vq->indirect = kmalloc_array(UIO_MAXIOV,
391 sizeof(*vq->indirect),
392 GFP_KERNEL);
393 vq->log = kmalloc_array(UIO_MAXIOV, sizeof(*vq->log),
394 GFP_KERNEL);
395 vq->heads = kmalloc_array(UIO_MAXIOV, sizeof(*vq->heads),
396 GFP_KERNEL);
397 if (!vq->indirect || !vq->log || !vq->heads)
398 goto err_nomem;
399 }
400 return 0;
401
402 err_nomem:
403 for (; i >= 0; --i)
404 vhost_vq_free_iovecs(dev->vqs[i]);
405 return -ENOMEM;
406 }
407
408 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
409 {
410 int i;
411
412 for (i = 0; i < dev->nvqs; ++i)
413 vhost_vq_free_iovecs(dev->vqs[i]);
414 }
415
416 void vhost_dev_init(struct vhost_dev *dev,
417 struct vhost_virtqueue **vqs, int nvqs)
418 {
419 struct vhost_virtqueue *vq;
420 int i;
421
422 dev->vqs = vqs;
423 dev->nvqs = nvqs;
424 mutex_init(&dev->mutex);
425 dev->log_ctx = NULL;
426 dev->umem = NULL;
427 dev->iotlb = NULL;
428 dev->mm = NULL;
429 dev->worker = NULL;
430 init_llist_head(&dev->work_list);
431 init_waitqueue_head(&dev->wait);
432 INIT_LIST_HEAD(&dev->read_list);
433 INIT_LIST_HEAD(&dev->pending_list);
434 spin_lock_init(&dev->iotlb_lock);
435
436
437 for (i = 0; i < dev->nvqs; ++i) {
438 vq = dev->vqs[i];
439 vq->log = NULL;
440 vq->indirect = NULL;
441 vq->heads = NULL;
442 vq->dev = dev;
443 mutex_init(&vq->mutex);
444 vhost_vq_reset(dev, vq);
445 if (vq->handle_kick)
446 vhost_poll_init(&vq->poll, vq->handle_kick,
447 EPOLLIN, dev);
448 }
449 }
450 EXPORT_SYMBOL_GPL(vhost_dev_init);
451
452 /* Caller should have device mutex */
453 long vhost_dev_check_owner(struct vhost_dev *dev)
454 {
455 /* Are you the owner? If not, I don't think you mean to do that */
456 return dev->mm == current->mm ? 0 : -EPERM;
457 }
458 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
459
460 struct vhost_attach_cgroups_struct {
461 struct vhost_work work;
462 struct task_struct *owner;
463 int ret;
464 };
465
466 static void vhost_attach_cgroups_work(struct vhost_work *work)
467 {
468 struct vhost_attach_cgroups_struct *s;
469
470 s = container_of(work, struct vhost_attach_cgroups_struct, work);
471 s->ret = cgroup_attach_task_all(s->owner, current);
472 }
473
474 static int vhost_attach_cgroups(struct vhost_dev *dev)
475 {
476 struct vhost_attach_cgroups_struct attach;
477
478 attach.owner = current;
479 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
480 vhost_work_queue(dev, &attach.work);
481 vhost_work_flush(dev, &attach.work);
482 return attach.ret;
483 }
484
485 /* Caller should have device mutex */
486 bool vhost_dev_has_owner(struct vhost_dev *dev)
487 {
488 return dev->mm;
489 }
490 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
491
492 /* Caller should have device mutex */
493 long vhost_dev_set_owner(struct vhost_dev *dev)
494 {
495 struct task_struct *worker;
496 int err;
497
498 /* Is there an owner already? */
499 if (vhost_dev_has_owner(dev)) {
500 err = -EBUSY;
501 goto err_mm;
502 }
503
504 /* No owner, become one */
505 dev->mm = get_task_mm(current);
506 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
507 if (IS_ERR(worker)) {
508 err = PTR_ERR(worker);
509 goto err_worker;
510 }
511
512 dev->worker = worker;
513 wake_up_process(worker); /* avoid contributing to loadavg */
514
515 err = vhost_attach_cgroups(dev);
516 if (err)
517 goto err_cgroup;
518
519 err = vhost_dev_alloc_iovecs(dev);
520 if (err)
521 goto err_cgroup;
522
523 return 0;
524 err_cgroup:
525 kthread_stop(worker);
526 dev->worker = NULL;
527 err_worker:
528 if (dev->mm)
529 mmput(dev->mm);
530 dev->mm = NULL;
531 err_mm:
532 return err;
533 }
534 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
535
536 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
537 {
538 return kvzalloc(sizeof(struct vhost_umem), GFP_KERNEL);
539 }
540 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
541
542 /* Caller should have device mutex */
543 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
544 {
545 int i;
546
547 vhost_dev_cleanup(dev);
548
549 /* Restore memory to default empty mapping. */
550 INIT_LIST_HEAD(&umem->umem_list);
551 dev->umem = umem;
552 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
553 * VQs aren't running.
554 */
555 for (i = 0; i < dev->nvqs; ++i)
556 dev->vqs[i]->umem = umem;
557 }
558 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
559
560 void vhost_dev_stop(struct vhost_dev *dev)
561 {
562 int i;
563
564 for (i = 0; i < dev->nvqs; ++i) {
565 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
566 vhost_poll_stop(&dev->vqs[i]->poll);
567 vhost_poll_flush(&dev->vqs[i]->poll);
568 }
569 }
570 }
571 EXPORT_SYMBOL_GPL(vhost_dev_stop);
572
573 static void vhost_umem_free(struct vhost_umem *umem,
574 struct vhost_umem_node *node)
575 {
576 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
577 list_del(&node->link);
578 kfree(node);
579 umem->numem--;
580 }
581
582 static void vhost_umem_clean(struct vhost_umem *umem)
583 {
584 struct vhost_umem_node *node, *tmp;
585
586 if (!umem)
587 return;
588
589 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
590 vhost_umem_free(umem, node);
591
592 kvfree(umem);
593 }
594
595 static void vhost_clear_msg(struct vhost_dev *dev)
596 {
597 struct vhost_msg_node *node, *n;
598
599 spin_lock(&dev->iotlb_lock);
600
601 list_for_each_entry_safe(node, n, &dev->read_list, node) {
602 list_del(&node->node);
603 kfree(node);
604 }
605
606 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
607 list_del(&node->node);
608 kfree(node);
609 }
610
611 spin_unlock(&dev->iotlb_lock);
612 }
613
614 void vhost_dev_cleanup(struct vhost_dev *dev)
615 {
616 int i;
617
618 for (i = 0; i < dev->nvqs; ++i) {
619 if (dev->vqs[i]->error_ctx)
620 eventfd_ctx_put(dev->vqs[i]->error_ctx);
621 if (dev->vqs[i]->kick)
622 fput(dev->vqs[i]->kick);
623 if (dev->vqs[i]->call_ctx)
624 eventfd_ctx_put(dev->vqs[i]->call_ctx);
625 vhost_vq_reset(dev, dev->vqs[i]);
626 }
627 vhost_dev_free_iovecs(dev);
628 if (dev->log_ctx)
629 eventfd_ctx_put(dev->log_ctx);
630 dev->log_ctx = NULL;
631 /* No one will access memory at this point */
632 vhost_umem_clean(dev->umem);
633 dev->umem = NULL;
634 vhost_umem_clean(dev->iotlb);
635 dev->iotlb = NULL;
636 vhost_clear_msg(dev);
637 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
638 WARN_ON(!llist_empty(&dev->work_list));
639 if (dev->worker) {
640 kthread_stop(dev->worker);
641 dev->worker = NULL;
642 }
643 if (dev->mm)
644 mmput(dev->mm);
645 dev->mm = NULL;
646 }
647 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
648
649 static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
650 {
651 u64 a = addr / VHOST_PAGE_SIZE / 8;
652
653 /* Make sure 64 bit math will not overflow. */
654 if (a > ULONG_MAX - (unsigned long)log_base ||
655 a + (unsigned long)log_base > ULONG_MAX)
656 return false;
657
658 return access_ok(log_base + a,
659 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
660 }
661
662 static bool vhost_overflow(u64 uaddr, u64 size)
663 {
664 /* Make sure 64 bit math will not overflow. */
665 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
666 }
667
668 /* Caller should have vq mutex and device mutex. */
669 static bool vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
670 int log_all)
671 {
672 struct vhost_umem_node *node;
673
674 if (!umem)
675 return false;
676
677 list_for_each_entry(node, &umem->umem_list, link) {
678 unsigned long a = node->userspace_addr;
679
680 if (vhost_overflow(node->userspace_addr, node->size))
681 return false;
682
683
684 if (!access_ok((void __user *)a,
685 node->size))
686 return false;
687 else if (log_all && !log_access_ok(log_base,
688 node->start,
689 node->size))
690 return false;
691 }
692 return true;
693 }
694
695 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
696 u64 addr, unsigned int size,
697 int type)
698 {
699 const struct vhost_umem_node *node = vq->meta_iotlb[type];
700
701 if (!node)
702 return NULL;
703
704 return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
705 }
706
707 /* Can we switch to this memory table? */
708 /* Caller should have device mutex but not vq mutex */
709 static bool memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
710 int log_all)
711 {
712 int i;
713
714 for (i = 0; i < d->nvqs; ++i) {
715 bool ok;
716 bool log;
717
718 mutex_lock(&d->vqs[i]->mutex);
719 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
720 /* If ring is inactive, will check when it's enabled. */
721 if (d->vqs[i]->private_data)
722 ok = vq_memory_access_ok(d->vqs[i]->log_base,
723 umem, log);
724 else
725 ok = true;
726 mutex_unlock(&d->vqs[i]->mutex);
727 if (!ok)
728 return false;
729 }
730 return true;
731 }
732
733 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
734 struct iovec iov[], int iov_size, int access);
735
736 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
737 const void *from, unsigned size)
738 {
739 int ret;
740
741 if (!vq->iotlb)
742 return __copy_to_user(to, from, size);
743 else {
744 /* This function should be called after iotlb
745 * prefetch, which means we're sure that all vq
746 * could be access through iotlb. So -EAGAIN should
747 * not happen in this case.
748 */
749 struct iov_iter t;
750 void __user *uaddr = vhost_vq_meta_fetch(vq,
751 (u64)(uintptr_t)to, size,
752 VHOST_ADDR_USED);
753
754 if (uaddr)
755 return __copy_to_user(uaddr, from, size);
756
757 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
758 ARRAY_SIZE(vq->iotlb_iov),
759 VHOST_ACCESS_WO);
760 if (ret < 0)
761 goto out;
762 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
763 ret = copy_to_iter(from, size, &t);
764 if (ret == size)
765 ret = 0;
766 }
767 out:
768 return ret;
769 }
770
771 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
772 void __user *from, unsigned size)
773 {
774 int ret;
775
776 if (!vq->iotlb)
777 return __copy_from_user(to, from, size);
778 else {
779 /* This function should be called after iotlb
780 * prefetch, which means we're sure that vq
781 * could be access through iotlb. So -EAGAIN should
782 * not happen in this case.
783 */
784 void __user *uaddr = vhost_vq_meta_fetch(vq,
785 (u64)(uintptr_t)from, size,
786 VHOST_ADDR_DESC);
787 struct iov_iter f;
788
789 if (uaddr)
790 return __copy_from_user(to, uaddr, size);
791
792 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
793 ARRAY_SIZE(vq->iotlb_iov),
794 VHOST_ACCESS_RO);
795 if (ret < 0) {
796 vq_err(vq, "IOTLB translation failure: uaddr "
797 "%p size 0x%llx\n", from,
798 (unsigned long long) size);
799 goto out;
800 }
801 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
802 ret = copy_from_iter(to, size, &f);
803 if (ret == size)
804 ret = 0;
805 }
806
807 out:
808 return ret;
809 }
810
811 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
812 void __user *addr, unsigned int size,
813 int type)
814 {
815 int ret;
816
817 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
818 ARRAY_SIZE(vq->iotlb_iov),
819 VHOST_ACCESS_RO);
820 if (ret < 0) {
821 vq_err(vq, "IOTLB translation failure: uaddr "
822 "%p size 0x%llx\n", addr,
823 (unsigned long long) size);
824 return NULL;
825 }
826
827 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
828 vq_err(vq, "Non atomic userspace memory access: uaddr "
829 "%p size 0x%llx\n", addr,
830 (unsigned long long) size);
831 return NULL;
832 }
833
834 return vq->iotlb_iov[0].iov_base;
835 }
836
837 /* This function should be called after iotlb
838 * prefetch, which means we're sure that vq
839 * could be access through iotlb. So -EAGAIN should
840 * not happen in this case.
841 */
842 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
843 void *addr, unsigned int size,
844 int type)
845 {
846 void __user *uaddr = vhost_vq_meta_fetch(vq,
847 (u64)(uintptr_t)addr, size, type);
848 if (uaddr)
849 return uaddr;
850
851 return __vhost_get_user_slow(vq, addr, size, type);
852 }
853
854 #define vhost_put_user(vq, x, ptr) \
855 ({ \
856 int ret = -EFAULT; \
857 if (!vq->iotlb) { \
858 ret = __put_user(x, ptr); \
859 } else { \
860 __typeof__(ptr) to = \
861 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
862 sizeof(*ptr), VHOST_ADDR_USED); \
863 if (to != NULL) \
864 ret = __put_user(x, to); \
865 else \
866 ret = -EFAULT; \
867 } \
868 ret; \
869 })
870
871 #define vhost_get_user(vq, x, ptr, type) \
872 ({ \
873 int ret; \
874 if (!vq->iotlb) { \
875 ret = __get_user(x, ptr); \
876 } else { \
877 __typeof__(ptr) from = \
878 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
879 sizeof(*ptr), \
880 type); \
881 if (from != NULL) \
882 ret = __get_user(x, from); \
883 else \
884 ret = -EFAULT; \
885 } \
886 ret; \
887 })
888
889 #define vhost_get_avail(vq, x, ptr) \
890 vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
891
892 #define vhost_get_used(vq, x, ptr) \
893 vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
894
895 static void vhost_dev_lock_vqs(struct vhost_dev *d)
896 {
897 int i = 0;
898 for (i = 0; i < d->nvqs; ++i)
899 mutex_lock_nested(&d->vqs[i]->mutex, i);
900 }
901
902 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
903 {
904 int i = 0;
905 for (i = 0; i < d->nvqs; ++i)
906 mutex_unlock(&d->vqs[i]->mutex);
907 }
908
909 static int vhost_new_umem_range(struct vhost_umem *umem,
910 u64 start, u64 size, u64 end,
911 u64 userspace_addr, int perm)
912 {
913 struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
914
915 if (!node)
916 return -ENOMEM;
917
918 if (umem->numem == max_iotlb_entries) {
919 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
920 vhost_umem_free(umem, tmp);
921 }
922
923 node->start = start;
924 node->size = size;
925 node->last = end;
926 node->userspace_addr = userspace_addr;
927 node->perm = perm;
928 INIT_LIST_HEAD(&node->link);
929 list_add_tail(&node->link, &umem->umem_list);
930 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
931 umem->numem++;
932
933 return 0;
934 }
935
936 static void vhost_del_umem_range(struct vhost_umem *umem,
937 u64 start, u64 end)
938 {
939 struct vhost_umem_node *node;
940
941 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
942 start, end)))
943 vhost_umem_free(umem, node);
944 }
945
946 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
947 struct vhost_iotlb_msg *msg)
948 {
949 struct vhost_msg_node *node, *n;
950
951 spin_lock(&d->iotlb_lock);
952
953 list_for_each_entry_safe(node, n, &d->pending_list, node) {
954 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
955 if (msg->iova <= vq_msg->iova &&
956 msg->iova + msg->size - 1 >= vq_msg->iova &&
957 vq_msg->type == VHOST_IOTLB_MISS) {
958 vhost_poll_queue(&node->vq->poll);
959 list_del(&node->node);
960 kfree(node);
961 }
962 }
963
964 spin_unlock(&d->iotlb_lock);
965 }
966
967 static bool umem_access_ok(u64 uaddr, u64 size, int access)
968 {
969 unsigned long a = uaddr;
970
971 /* Make sure 64 bit math will not overflow. */
972 if (vhost_overflow(uaddr, size))
973 return false;
974
975 if ((access & VHOST_ACCESS_RO) &&
976 !access_ok((void __user *)a, size))
977 return false;
978 if ((access & VHOST_ACCESS_WO) &&
979 !access_ok((void __user *)a, size))
980 return false;
981 return true;
982 }
983
984 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
985 struct vhost_iotlb_msg *msg)
986 {
987 int ret = 0;
988
989 mutex_lock(&dev->mutex);
990 vhost_dev_lock_vqs(dev);
991 switch (msg->type) {
992 case VHOST_IOTLB_UPDATE:
993 if (!dev->iotlb) {
994 ret = -EFAULT;
995 break;
996 }
997 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
998 ret = -EFAULT;
999 break;
1000 }
1001 vhost_vq_meta_reset(dev);
1002 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
1003 msg->iova + msg->size - 1,
1004 msg->uaddr, msg->perm)) {
1005 ret = -ENOMEM;
1006 break;
1007 }
1008 vhost_iotlb_notify_vq(dev, msg);
1009 break;
1010 case VHOST_IOTLB_INVALIDATE:
1011 if (!dev->iotlb) {
1012 ret = -EFAULT;
1013 break;
1014 }
1015 vhost_vq_meta_reset(dev);
1016 vhost_del_umem_range(dev->iotlb, msg->iova,
1017 msg->iova + msg->size - 1);
1018 break;
1019 default:
1020 ret = -EINVAL;
1021 break;
1022 }
1023
1024 vhost_dev_unlock_vqs(dev);
1025 mutex_unlock(&dev->mutex);
1026
1027 return ret;
1028 }
1029 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1030 struct iov_iter *from)
1031 {
1032 struct vhost_iotlb_msg msg;
1033 size_t offset;
1034 int type, ret;
1035
1036 ret = copy_from_iter(&type, sizeof(type), from);
1037 if (ret != sizeof(type))
1038 goto done;
1039
1040 switch (type) {
1041 case VHOST_IOTLB_MSG:
1042 /* There maybe a hole after type for V1 message type,
1043 * so skip it here.
1044 */
1045 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1046 break;
1047 case VHOST_IOTLB_MSG_V2:
1048 offset = sizeof(__u32);
1049 break;
1050 default:
1051 ret = -EINVAL;
1052 goto done;
1053 }
1054
1055 iov_iter_advance(from, offset);
1056 ret = copy_from_iter(&msg, sizeof(msg), from);
1057 if (ret != sizeof(msg))
1058 goto done;
1059 if (vhost_process_iotlb_msg(dev, &msg)) {
1060 ret = -EFAULT;
1061 goto done;
1062 }
1063
1064 ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1065 sizeof(struct vhost_msg_v2);
1066 done:
1067 return ret;
1068 }
1069 EXPORT_SYMBOL(vhost_chr_write_iter);
1070
1071 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1072 poll_table *wait)
1073 {
1074 __poll_t mask = 0;
1075
1076 poll_wait(file, &dev->wait, wait);
1077
1078 if (!list_empty(&dev->read_list))
1079 mask |= EPOLLIN | EPOLLRDNORM;
1080
1081 return mask;
1082 }
1083 EXPORT_SYMBOL(vhost_chr_poll);
1084
1085 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1086 int noblock)
1087 {
1088 DEFINE_WAIT(wait);
1089 struct vhost_msg_node *node;
1090 ssize_t ret = 0;
1091 unsigned size = sizeof(struct vhost_msg);
1092
1093 if (iov_iter_count(to) < size)
1094 return 0;
1095
1096 while (1) {
1097 if (!noblock)
1098 prepare_to_wait(&dev->wait, &wait,
1099 TASK_INTERRUPTIBLE);
1100
1101 node = vhost_dequeue_msg(dev, &dev->read_list);
1102 if (node)
1103 break;
1104 if (noblock) {
1105 ret = -EAGAIN;
1106 break;
1107 }
1108 if (signal_pending(current)) {
1109 ret = -ERESTARTSYS;
1110 break;
1111 }
1112 if (!dev->iotlb) {
1113 ret = -EBADFD;
1114 break;
1115 }
1116
1117 schedule();
1118 }
1119
1120 if (!noblock)
1121 finish_wait(&dev->wait, &wait);
1122
1123 if (node) {
1124 struct vhost_iotlb_msg *msg;
1125 void *start = &node->msg;
1126
1127 switch (node->msg.type) {
1128 case VHOST_IOTLB_MSG:
1129 size = sizeof(node->msg);
1130 msg = &node->msg.iotlb;
1131 break;
1132 case VHOST_IOTLB_MSG_V2:
1133 size = sizeof(node->msg_v2);
1134 msg = &node->msg_v2.iotlb;
1135 break;
1136 default:
1137 BUG();
1138 break;
1139 }
1140
1141 ret = copy_to_iter(start, size, to);
1142 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1143 kfree(node);
1144 return ret;
1145 }
1146 vhost_enqueue_msg(dev, &dev->pending_list, node);
1147 }
1148
1149 return ret;
1150 }
1151 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1152
1153 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1154 {
1155 struct vhost_dev *dev = vq->dev;
1156 struct vhost_msg_node *node;
1157 struct vhost_iotlb_msg *msg;
1158 bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1159
1160 node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1161 if (!node)
1162 return -ENOMEM;
1163
1164 if (v2) {
1165 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1166 msg = &node->msg_v2.iotlb;
1167 } else {
1168 msg = &node->msg.iotlb;
1169 }
1170
1171 msg->type = VHOST_IOTLB_MISS;
1172 msg->iova = iova;
1173 msg->perm = access;
1174
1175 vhost_enqueue_msg(dev, &dev->read_list, node);
1176
1177 return 0;
1178 }
1179
1180 static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1181 struct vring_desc __user *desc,
1182 struct vring_avail __user *avail,
1183 struct vring_used __user *used)
1184
1185 {
1186 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1187
1188 return access_ok(desc, num * sizeof *desc) &&
1189 access_ok(avail,
1190 sizeof *avail + num * sizeof *avail->ring + s) &&
1191 access_ok(used,
1192 sizeof *used + num * sizeof *used->ring + s);
1193 }
1194
1195 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1196 const struct vhost_umem_node *node,
1197 int type)
1198 {
1199 int access = (type == VHOST_ADDR_USED) ?
1200 VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1201
1202 if (likely(node->perm & access))
1203 vq->meta_iotlb[type] = node;
1204 }
1205
1206 static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1207 int access, u64 addr, u64 len, int type)
1208 {
1209 const struct vhost_umem_node *node;
1210 struct vhost_umem *umem = vq->iotlb;
1211 u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1212
1213 if (vhost_vq_meta_fetch(vq, addr, len, type))
1214 return true;
1215
1216 while (len > s) {
1217 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1218 addr,
1219 last);
1220 if (node == NULL || node->start > addr) {
1221 vhost_iotlb_miss(vq, addr, access);
1222 return false;
1223 } else if (!(node->perm & access)) {
1224 /* Report the possible access violation by
1225 * request another translation from userspace.
1226 */
1227 return false;
1228 }
1229
1230 size = node->size - addr + node->start;
1231
1232 if (orig_addr == addr && size >= len)
1233 vhost_vq_meta_update(vq, node, type);
1234
1235 s += size;
1236 addr += size;
1237 }
1238
1239 return true;
1240 }
1241
1242 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1243 {
1244 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1245 unsigned int num = vq->num;
1246
1247 if (!vq->iotlb)
1248 return 1;
1249
1250 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1251 num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
1252 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1253 sizeof *vq->avail +
1254 num * sizeof(*vq->avail->ring) + s,
1255 VHOST_ADDR_AVAIL) &&
1256 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1257 sizeof *vq->used +
1258 num * sizeof(*vq->used->ring) + s,
1259 VHOST_ADDR_USED);
1260 }
1261 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1262
1263 /* Can we log writes? */
1264 /* Caller should have device mutex but not vq mutex */
1265 bool vhost_log_access_ok(struct vhost_dev *dev)
1266 {
1267 return memory_access_ok(dev, dev->umem, 1);
1268 }
1269 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1270
1271 /* Verify access for write logging. */
1272 /* Caller should have vq mutex and device mutex */
1273 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1274 void __user *log_base)
1275 {
1276 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1277
1278 return vq_memory_access_ok(log_base, vq->umem,
1279 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1280 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1281 sizeof *vq->used +
1282 vq->num * sizeof *vq->used->ring + s));
1283 }
1284
1285 /* Can we start vq? */
1286 /* Caller should have vq mutex and device mutex */
1287 bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1288 {
1289 if (!vq_log_access_ok(vq, vq->log_base))
1290 return false;
1291
1292 /* Access validation occurs at prefetch time with IOTLB */
1293 if (vq->iotlb)
1294 return true;
1295
1296 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1297 }
1298 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1299
1300 static struct vhost_umem *vhost_umem_alloc(void)
1301 {
1302 struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1303
1304 if (!umem)
1305 return NULL;
1306
1307 umem->umem_tree = RB_ROOT_CACHED;
1308 umem->numem = 0;
1309 INIT_LIST_HEAD(&umem->umem_list);
1310
1311 return umem;
1312 }
1313
1314 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1315 {
1316 struct vhost_memory mem, *newmem;
1317 struct vhost_memory_region *region;
1318 struct vhost_umem *newumem, *oldumem;
1319 unsigned long size = offsetof(struct vhost_memory, regions);
1320 int i;
1321
1322 if (copy_from_user(&mem, m, size))
1323 return -EFAULT;
1324 if (mem.padding)
1325 return -EOPNOTSUPP;
1326 if (mem.nregions > max_mem_regions)
1327 return -E2BIG;
1328 newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1329 GFP_KERNEL);
1330 if (!newmem)
1331 return -ENOMEM;
1332
1333 memcpy(newmem, &mem, size);
1334 if (copy_from_user(newmem->regions, m->regions,
1335 mem.nregions * sizeof *m->regions)) {
1336 kvfree(newmem);
1337 return -EFAULT;
1338 }
1339
1340 newumem = vhost_umem_alloc();
1341 if (!newumem) {
1342 kvfree(newmem);
1343 return -ENOMEM;
1344 }
1345
1346 for (region = newmem->regions;
1347 region < newmem->regions + mem.nregions;
1348 region++) {
1349 if (vhost_new_umem_range(newumem,
1350 region->guest_phys_addr,
1351 region->memory_size,
1352 region->guest_phys_addr +
1353 region->memory_size - 1,
1354 region->userspace_addr,
1355 VHOST_ACCESS_RW))
1356 goto err;
1357 }
1358
1359 if (!memory_access_ok(d, newumem, 0))
1360 goto err;
1361
1362 oldumem = d->umem;
1363 d->umem = newumem;
1364
1365 /* All memory accesses are done under some VQ mutex. */
1366 for (i = 0; i < d->nvqs; ++i) {
1367 mutex_lock(&d->vqs[i]->mutex);
1368 d->vqs[i]->umem = newumem;
1369 mutex_unlock(&d->vqs[i]->mutex);
1370 }
1371
1372 kvfree(newmem);
1373 vhost_umem_clean(oldumem);
1374 return 0;
1375
1376 err:
1377 vhost_umem_clean(newumem);
1378 kvfree(newmem);
1379 return -EFAULT;
1380 }
1381
1382 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1383 {
1384 struct file *eventfp, *filep = NULL;
1385 bool pollstart = false, pollstop = false;
1386 struct eventfd_ctx *ctx = NULL;
1387 u32 __user *idxp = argp;
1388 struct vhost_virtqueue *vq;
1389 struct vhost_vring_state s;
1390 struct vhost_vring_file f;
1391 struct vhost_vring_addr a;
1392 u32 idx;
1393 long r;
1394
1395 r = get_user(idx, idxp);
1396 if (r < 0)
1397 return r;
1398 if (idx >= d->nvqs)
1399 return -ENOBUFS;
1400
1401 idx = array_index_nospec(idx, d->nvqs);
1402 vq = d->vqs[idx];
1403
1404 mutex_lock(&vq->mutex);
1405
1406 switch (ioctl) {
1407 case VHOST_SET_VRING_NUM:
1408 /* Resizing ring with an active backend?
1409 * You don't want to do that. */
1410 if (vq->private_data) {
1411 r = -EBUSY;
1412 break;
1413 }
1414 if (copy_from_user(&s, argp, sizeof s)) {
1415 r = -EFAULT;
1416 break;
1417 }
1418 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1419 r = -EINVAL;
1420 break;
1421 }
1422 vq->num = s.num;
1423 break;
1424 case VHOST_SET_VRING_BASE:
1425 /* Moving base with an active backend?
1426 * You don't want to do that. */
1427 if (vq->private_data) {
1428 r = -EBUSY;
1429 break;
1430 }
1431 if (copy_from_user(&s, argp, sizeof s)) {
1432 r = -EFAULT;
1433 break;
1434 }
1435 if (s.num > 0xffff) {
1436 r = -EINVAL;
1437 break;
1438 }
1439 vq->last_avail_idx = s.num;
1440 /* Forget the cached index value. */
1441 vq->avail_idx = vq->last_avail_idx;
1442 break;
1443 case VHOST_GET_VRING_BASE:
1444 s.index = idx;
1445 s.num = vq->last_avail_idx;
1446 if (copy_to_user(argp, &s, sizeof s))
1447 r = -EFAULT;
1448 break;
1449 case VHOST_SET_VRING_ADDR:
1450 if (copy_from_user(&a, argp, sizeof a)) {
1451 r = -EFAULT;
1452 break;
1453 }
1454 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1455 r = -EOPNOTSUPP;
1456 break;
1457 }
1458 /* For 32bit, verify that the top 32bits of the user
1459 data are set to zero. */
1460 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1461 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1462 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1463 r = -EFAULT;
1464 break;
1465 }
1466
1467 /* Make sure it's safe to cast pointers to vring types. */
1468 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1469 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1470 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1471 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1472 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1473 r = -EINVAL;
1474 break;
1475 }
1476
1477 /* We only verify access here if backend is configured.
1478 * If it is not, we don't as size might not have been setup.
1479 * We will verify when backend is configured. */
1480 if (vq->private_data) {
1481 if (!vq_access_ok(vq, vq->num,
1482 (void __user *)(unsigned long)a.desc_user_addr,
1483 (void __user *)(unsigned long)a.avail_user_addr,
1484 (void __user *)(unsigned long)a.used_user_addr)) {
1485 r = -EINVAL;
1486 break;
1487 }
1488
1489 /* Also validate log access for used ring if enabled. */
1490 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1491 !log_access_ok(vq->log_base, a.log_guest_addr,
1492 sizeof *vq->used +
1493 vq->num * sizeof *vq->used->ring)) {
1494 r = -EINVAL;
1495 break;
1496 }
1497 }
1498
1499 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1500 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1501 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1502 vq->log_addr = a.log_guest_addr;
1503 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1504 break;
1505 case VHOST_SET_VRING_KICK:
1506 if (copy_from_user(&f, argp, sizeof f)) {
1507 r = -EFAULT;
1508 break;
1509 }
1510 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1511 if (IS_ERR(eventfp)) {
1512 r = PTR_ERR(eventfp);
1513 break;
1514 }
1515 if (eventfp != vq->kick) {
1516 pollstop = (filep = vq->kick) != NULL;
1517 pollstart = (vq->kick = eventfp) != NULL;
1518 } else
1519 filep = eventfp;
1520 break;
1521 case VHOST_SET_VRING_CALL:
1522 if (copy_from_user(&f, argp, sizeof f)) {
1523 r = -EFAULT;
1524 break;
1525 }
1526 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1527 if (IS_ERR(ctx)) {
1528 r = PTR_ERR(ctx);
1529 break;
1530 }
1531 swap(ctx, vq->call_ctx);
1532 break;
1533 case VHOST_SET_VRING_ERR:
1534 if (copy_from_user(&f, argp, sizeof f)) {
1535 r = -EFAULT;
1536 break;
1537 }
1538 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1539 if (IS_ERR(ctx)) {
1540 r = PTR_ERR(ctx);
1541 break;
1542 }
1543 swap(ctx, vq->error_ctx);
1544 break;
1545 case VHOST_SET_VRING_ENDIAN:
1546 r = vhost_set_vring_endian(vq, argp);
1547 break;
1548 case VHOST_GET_VRING_ENDIAN:
1549 r = vhost_get_vring_endian(vq, idx, argp);
1550 break;
1551 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1552 if (copy_from_user(&s, argp, sizeof(s))) {
1553 r = -EFAULT;
1554 break;
1555 }
1556 vq->busyloop_timeout = s.num;
1557 break;
1558 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1559 s.index = idx;
1560 s.num = vq->busyloop_timeout;
1561 if (copy_to_user(argp, &s, sizeof(s)))
1562 r = -EFAULT;
1563 break;
1564 default:
1565 r = -ENOIOCTLCMD;
1566 }
1567
1568 if (pollstop && vq->handle_kick)
1569 vhost_poll_stop(&vq->poll);
1570
1571 if (!IS_ERR_OR_NULL(ctx))
1572 eventfd_ctx_put(ctx);
1573 if (filep)
1574 fput(filep);
1575
1576 if (pollstart && vq->handle_kick)
1577 r = vhost_poll_start(&vq->poll, vq->kick);
1578
1579 mutex_unlock(&vq->mutex);
1580
1581 if (pollstop && vq->handle_kick)
1582 vhost_poll_flush(&vq->poll);
1583 return r;
1584 }
1585 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1586
1587 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1588 {
1589 struct vhost_umem *niotlb, *oiotlb;
1590 int i;
1591
1592 niotlb = vhost_umem_alloc();
1593 if (!niotlb)
1594 return -ENOMEM;
1595
1596 oiotlb = d->iotlb;
1597 d->iotlb = niotlb;
1598
1599 for (i = 0; i < d->nvqs; ++i) {
1600 struct vhost_virtqueue *vq = d->vqs[i];
1601
1602 mutex_lock(&vq->mutex);
1603 vq->iotlb = niotlb;
1604 __vhost_vq_meta_reset(vq);
1605 mutex_unlock(&vq->mutex);
1606 }
1607
1608 vhost_umem_clean(oiotlb);
1609
1610 return 0;
1611 }
1612 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1613
1614 /* Caller must have device mutex */
1615 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1616 {
1617 struct eventfd_ctx *ctx;
1618 u64 p;
1619 long r;
1620 int i, fd;
1621
1622 /* If you are not the owner, you can become one */
1623 if (ioctl == VHOST_SET_OWNER) {
1624 r = vhost_dev_set_owner(d);
1625 goto done;
1626 }
1627
1628 /* You must be the owner to do anything else */
1629 r = vhost_dev_check_owner(d);
1630 if (r)
1631 goto done;
1632
1633 switch (ioctl) {
1634 case VHOST_SET_MEM_TABLE:
1635 r = vhost_set_memory(d, argp);
1636 break;
1637 case VHOST_SET_LOG_BASE:
1638 if (copy_from_user(&p, argp, sizeof p)) {
1639 r = -EFAULT;
1640 break;
1641 }
1642 if ((u64)(unsigned long)p != p) {
1643 r = -EFAULT;
1644 break;
1645 }
1646 for (i = 0; i < d->nvqs; ++i) {
1647 struct vhost_virtqueue *vq;
1648 void __user *base = (void __user *)(unsigned long)p;
1649 vq = d->vqs[i];
1650 mutex_lock(&vq->mutex);
1651 /* If ring is inactive, will check when it's enabled. */
1652 if (vq->private_data && !vq_log_access_ok(vq, base))
1653 r = -EFAULT;
1654 else
1655 vq->log_base = base;
1656 mutex_unlock(&vq->mutex);
1657 }
1658 break;
1659 case VHOST_SET_LOG_FD:
1660 r = get_user(fd, (int __user *)argp);
1661 if (r < 0)
1662 break;
1663 ctx = fd == -1 ? NULL : eventfd_ctx_fdget(fd);
1664 if (IS_ERR(ctx)) {
1665 r = PTR_ERR(ctx);
1666 break;
1667 }
1668 swap(ctx, d->log_ctx);
1669 for (i = 0; i < d->nvqs; ++i) {
1670 mutex_lock(&d->vqs[i]->mutex);
1671 d->vqs[i]->log_ctx = d->log_ctx;
1672 mutex_unlock(&d->vqs[i]->mutex);
1673 }
1674 if (ctx)
1675 eventfd_ctx_put(ctx);
1676 break;
1677 default:
1678 r = -ENOIOCTLCMD;
1679 break;
1680 }
1681 done:
1682 return r;
1683 }
1684 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1685
1686 /* TODO: This is really inefficient. We need something like get_user()
1687 * (instruction directly accesses the data, with an exception table entry
1688 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1689 */
1690 static int set_bit_to_user(int nr, void __user *addr)
1691 {
1692 unsigned long log = (unsigned long)addr;
1693 struct page *page;
1694 void *base;
1695 int bit = nr + (log % PAGE_SIZE) * 8;
1696 int r;
1697
1698 r = get_user_pages_fast(log, 1, 1, &page);
1699 if (r < 0)
1700 return r;
1701 BUG_ON(r != 1);
1702 base = kmap_atomic(page);
1703 set_bit(bit, base);
1704 kunmap_atomic(base);
1705 set_page_dirty_lock(page);
1706 put_page(page);
1707 return 0;
1708 }
1709
1710 static int log_write(void __user *log_base,
1711 u64 write_address, u64 write_length)
1712 {
1713 u64 write_page = write_address / VHOST_PAGE_SIZE;
1714 int r;
1715
1716 if (!write_length)
1717 return 0;
1718 write_length += write_address % VHOST_PAGE_SIZE;
1719 for (;;) {
1720 u64 base = (u64)(unsigned long)log_base;
1721 u64 log = base + write_page / 8;
1722 int bit = write_page % 8;
1723 if ((u64)(unsigned long)log != log)
1724 return -EFAULT;
1725 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1726 if (r < 0)
1727 return r;
1728 if (write_length <= VHOST_PAGE_SIZE)
1729 break;
1730 write_length -= VHOST_PAGE_SIZE;
1731 write_page += 1;
1732 }
1733 return r;
1734 }
1735
1736 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1737 unsigned int log_num, u64 len)
1738 {
1739 int i, r;
1740
1741 /* Make sure data written is seen before log. */
1742 smp_wmb();
1743 for (i = 0; i < log_num; ++i) {
1744 u64 l = min(log[i].len, len);
1745 r = log_write(vq->log_base, log[i].addr, l);
1746 if (r < 0)
1747 return r;
1748 len -= l;
1749 if (!len) {
1750 if (vq->log_ctx)
1751 eventfd_signal(vq->log_ctx, 1);
1752 return 0;
1753 }
1754 }
1755 /* Length written exceeds what we have stored. This is a bug. */
1756 BUG();
1757 return 0;
1758 }
1759 EXPORT_SYMBOL_GPL(vhost_log_write);
1760
1761 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1762 {
1763 void __user *used;
1764 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1765 &vq->used->flags) < 0)
1766 return -EFAULT;
1767 if (unlikely(vq->log_used)) {
1768 /* Make sure the flag is seen before log. */
1769 smp_wmb();
1770 /* Log used flag write. */
1771 used = &vq->used->flags;
1772 log_write(vq->log_base, vq->log_addr +
1773 (used - (void __user *)vq->used),
1774 sizeof vq->used->flags);
1775 if (vq->log_ctx)
1776 eventfd_signal(vq->log_ctx, 1);
1777 }
1778 return 0;
1779 }
1780
1781 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1782 {
1783 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1784 vhost_avail_event(vq)))
1785 return -EFAULT;
1786 if (unlikely(vq->log_used)) {
1787 void __user *used;
1788 /* Make sure the event is seen before log. */
1789 smp_wmb();
1790 /* Log avail event write */
1791 used = vhost_avail_event(vq);
1792 log_write(vq->log_base, vq->log_addr +
1793 (used - (void __user *)vq->used),
1794 sizeof *vhost_avail_event(vq));
1795 if (vq->log_ctx)
1796 eventfd_signal(vq->log_ctx, 1);
1797 }
1798 return 0;
1799 }
1800
1801 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1802 {
1803 __virtio16 last_used_idx;
1804 int r;
1805 bool is_le = vq->is_le;
1806
1807 if (!vq->private_data)
1808 return 0;
1809
1810 vhost_init_is_le(vq);
1811
1812 r = vhost_update_used_flags(vq);
1813 if (r)
1814 goto err;
1815 vq->signalled_used_valid = false;
1816 if (!vq->iotlb &&
1817 !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
1818 r = -EFAULT;
1819 goto err;
1820 }
1821 r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
1822 if (r) {
1823 vq_err(vq, "Can't access used idx at %p\n",
1824 &vq->used->idx);
1825 goto err;
1826 }
1827 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1828 return 0;
1829
1830 err:
1831 vq->is_le = is_le;
1832 return r;
1833 }
1834 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1835
1836 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1837 struct iovec iov[], int iov_size, int access)
1838 {
1839 const struct vhost_umem_node *node;
1840 struct vhost_dev *dev = vq->dev;
1841 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1842 struct iovec *_iov;
1843 u64 s = 0;
1844 int ret = 0;
1845
1846 while ((u64)len > s) {
1847 u64 size;
1848 if (unlikely(ret >= iov_size)) {
1849 ret = -ENOBUFS;
1850 break;
1851 }
1852
1853 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1854 addr, addr + len - 1);
1855 if (node == NULL || node->start > addr) {
1856 if (umem != dev->iotlb) {
1857 ret = -EFAULT;
1858 break;
1859 }
1860 ret = -EAGAIN;
1861 break;
1862 } else if (!(node->perm & access)) {
1863 ret = -EPERM;
1864 break;
1865 }
1866
1867 _iov = iov + ret;
1868 size = node->size - addr + node->start;
1869 _iov->iov_len = min((u64)len - s, size);
1870 _iov->iov_base = (void __user *)(unsigned long)
1871 (node->userspace_addr + addr - node->start);
1872 s += size;
1873 addr += size;
1874 ++ret;
1875 }
1876
1877 if (ret == -EAGAIN)
1878 vhost_iotlb_miss(vq, addr, access);
1879 return ret;
1880 }
1881
1882 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1883 * function returns the next descriptor in the chain,
1884 * or -1U if we're at the end. */
1885 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1886 {
1887 unsigned int next;
1888
1889 /* If this descriptor says it doesn't chain, we're done. */
1890 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1891 return -1U;
1892
1893 /* Check they're not leading us off end of descriptors. */
1894 next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
1895 return next;
1896 }
1897
1898 static int get_indirect(struct vhost_virtqueue *vq,
1899 struct iovec iov[], unsigned int iov_size,
1900 unsigned int *out_num, unsigned int *in_num,
1901 struct vhost_log *log, unsigned int *log_num,
1902 struct vring_desc *indirect)
1903 {
1904 struct vring_desc desc;
1905 unsigned int i = 0, count, found = 0;
1906 u32 len = vhost32_to_cpu(vq, indirect->len);
1907 struct iov_iter from;
1908 int ret, access;
1909
1910 /* Sanity check */
1911 if (unlikely(len % sizeof desc)) {
1912 vq_err(vq, "Invalid length in indirect descriptor: "
1913 "len 0x%llx not multiple of 0x%zx\n",
1914 (unsigned long long)len,
1915 sizeof desc);
1916 return -EINVAL;
1917 }
1918
1919 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1920 UIO_MAXIOV, VHOST_ACCESS_RO);
1921 if (unlikely(ret < 0)) {
1922 if (ret != -EAGAIN)
1923 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1924 return ret;
1925 }
1926 iov_iter_init(&from, READ, vq->indirect, ret, len);
1927
1928 /* We will use the result as an address to read from, so most
1929 * architectures only need a compiler barrier here. */
1930 read_barrier_depends();
1931
1932 count = len / sizeof desc;
1933 /* Buffers are chained via a 16 bit next field, so
1934 * we can have at most 2^16 of these. */
1935 if (unlikely(count > USHRT_MAX + 1)) {
1936 vq_err(vq, "Indirect buffer length too big: %d\n",
1937 indirect->len);
1938 return -E2BIG;
1939 }
1940
1941 do {
1942 unsigned iov_count = *in_num + *out_num;
1943 if (unlikely(++found > count)) {
1944 vq_err(vq, "Loop detected: last one at %u "
1945 "indirect size %u\n",
1946 i, count);
1947 return -EINVAL;
1948 }
1949 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1950 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1951 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1952 return -EINVAL;
1953 }
1954 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1955 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1956 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1957 return -EINVAL;
1958 }
1959
1960 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1961 access = VHOST_ACCESS_WO;
1962 else
1963 access = VHOST_ACCESS_RO;
1964
1965 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1966 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1967 iov_size - iov_count, access);
1968 if (unlikely(ret < 0)) {
1969 if (ret != -EAGAIN)
1970 vq_err(vq, "Translation failure %d indirect idx %d\n",
1971 ret, i);
1972 return ret;
1973 }
1974 /* If this is an input descriptor, increment that count. */
1975 if (access == VHOST_ACCESS_WO) {
1976 *in_num += ret;
1977 if (unlikely(log)) {
1978 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1979 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1980 ++*log_num;
1981 }
1982 } else {
1983 /* If it's an output descriptor, they're all supposed
1984 * to come before any input descriptors. */
1985 if (unlikely(*in_num)) {
1986 vq_err(vq, "Indirect descriptor "
1987 "has out after in: idx %d\n", i);
1988 return -EINVAL;
1989 }
1990 *out_num += ret;
1991 }
1992 } while ((i = next_desc(vq, &desc)) != -1);
1993 return 0;
1994 }
1995
1996 /* This looks in the virtqueue and for the first available buffer, and converts
1997 * it to an iovec for convenient access. Since descriptors consist of some
1998 * number of output then some number of input descriptors, it's actually two
1999 * iovecs, but we pack them into one and note how many of each there were.
2000 *
2001 * This function returns the descriptor number found, or vq->num (which is
2002 * never a valid descriptor number) if none was found. A negative code is
2003 * returned on error. */
2004 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2005 struct iovec iov[], unsigned int iov_size,
2006 unsigned int *out_num, unsigned int *in_num,
2007 struct vhost_log *log, unsigned int *log_num)
2008 {
2009 struct vring_desc desc;
2010 unsigned int i, head, found = 0;
2011 u16 last_avail_idx;
2012 __virtio16 avail_idx;
2013 __virtio16 ring_head;
2014 int ret, access;
2015
2016 /* Check it isn't doing very strange things with descriptor numbers. */
2017 last_avail_idx = vq->last_avail_idx;
2018
2019 if (vq->avail_idx == vq->last_avail_idx) {
2020 if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
2021 vq_err(vq, "Failed to access avail idx at %p\n",
2022 &vq->avail->idx);
2023 return -EFAULT;
2024 }
2025 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2026
2027 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2028 vq_err(vq, "Guest moved used index from %u to %u",
2029 last_avail_idx, vq->avail_idx);
2030 return -EFAULT;
2031 }
2032
2033 /* If there's nothing new since last we looked, return
2034 * invalid.
2035 */
2036 if (vq->avail_idx == last_avail_idx)
2037 return vq->num;
2038
2039 /* Only get avail ring entries after they have been
2040 * exposed by guest.
2041 */
2042 smp_rmb();
2043 }
2044
2045 /* Grab the next descriptor number they're advertising, and increment
2046 * the index we've seen. */
2047 if (unlikely(vhost_get_avail(vq, ring_head,
2048 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
2049 vq_err(vq, "Failed to read head: idx %d address %p\n",
2050 last_avail_idx,
2051 &vq->avail->ring[last_avail_idx % vq->num]);
2052 return -EFAULT;
2053 }
2054
2055 head = vhost16_to_cpu(vq, ring_head);
2056
2057 /* If their number is silly, that's an error. */
2058 if (unlikely(head >= vq->num)) {
2059 vq_err(vq, "Guest says index %u > %u is available",
2060 head, vq->num);
2061 return -EINVAL;
2062 }
2063
2064 /* When we start there are none of either input nor output. */
2065 *out_num = *in_num = 0;
2066 if (unlikely(log))
2067 *log_num = 0;
2068
2069 i = head;
2070 do {
2071 unsigned iov_count = *in_num + *out_num;
2072 if (unlikely(i >= vq->num)) {
2073 vq_err(vq, "Desc index is %u > %u, head = %u",
2074 i, vq->num, head);
2075 return -EINVAL;
2076 }
2077 if (unlikely(++found > vq->num)) {
2078 vq_err(vq, "Loop detected: last one at %u "
2079 "vq size %u head %u\n",
2080 i, vq->num, head);
2081 return -EINVAL;
2082 }
2083 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
2084 sizeof desc);
2085 if (unlikely(ret)) {
2086 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2087 i, vq->desc + i);
2088 return -EFAULT;
2089 }
2090 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2091 ret = get_indirect(vq, iov, iov_size,
2092 out_num, in_num,
2093 log, log_num, &desc);
2094 if (unlikely(ret < 0)) {
2095 if (ret != -EAGAIN)
2096 vq_err(vq, "Failure detected "
2097 "in indirect descriptor at idx %d\n", i);
2098 return ret;
2099 }
2100 continue;
2101 }
2102
2103 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2104 access = VHOST_ACCESS_WO;
2105 else
2106 access = VHOST_ACCESS_RO;
2107 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2108 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2109 iov_size - iov_count, access);
2110 if (unlikely(ret < 0)) {
2111 if (ret != -EAGAIN)
2112 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2113 ret, i);
2114 return ret;
2115 }
2116 if (access == VHOST_ACCESS_WO) {
2117 /* If this is an input descriptor,
2118 * increment that count. */
2119 *in_num += ret;
2120 if (unlikely(log)) {
2121 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2122 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2123 ++*log_num;
2124 }
2125 } else {
2126 /* If it's an output descriptor, they're all supposed
2127 * to come before any input descriptors. */
2128 if (unlikely(*in_num)) {
2129 vq_err(vq, "Descriptor has out after in: "
2130 "idx %d\n", i);
2131 return -EINVAL;
2132 }
2133 *out_num += ret;
2134 }
2135 } while ((i = next_desc(vq, &desc)) != -1);
2136
2137 /* On success, increment avail index. */
2138 vq->last_avail_idx++;
2139
2140 /* Assume notifications from guest are disabled at this point,
2141 * if they aren't we would need to update avail_event index. */
2142 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2143 return head;
2144 }
2145 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2146
2147 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2148 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2149 {
2150 vq->last_avail_idx -= n;
2151 }
2152 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2153
2154 /* After we've used one of their buffers, we tell them about it. We'll then
2155 * want to notify the guest, using eventfd. */
2156 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2157 {
2158 struct vring_used_elem heads = {
2159 cpu_to_vhost32(vq, head),
2160 cpu_to_vhost32(vq, len)
2161 };
2162
2163 return vhost_add_used_n(vq, &heads, 1);
2164 }
2165 EXPORT_SYMBOL_GPL(vhost_add_used);
2166
2167 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2168 struct vring_used_elem *heads,
2169 unsigned count)
2170 {
2171 struct vring_used_elem __user *used;
2172 u16 old, new;
2173 int start;
2174
2175 start = vq->last_used_idx & (vq->num - 1);
2176 used = vq->used->ring + start;
2177 if (count == 1) {
2178 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2179 vq_err(vq, "Failed to write used id");
2180 return -EFAULT;
2181 }
2182 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2183 vq_err(vq, "Failed to write used len");
2184 return -EFAULT;
2185 }
2186 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2187 vq_err(vq, "Failed to write used");
2188 return -EFAULT;
2189 }
2190 if (unlikely(vq->log_used)) {
2191 /* Make sure data is seen before log. */
2192 smp_wmb();
2193 /* Log used ring entry write. */
2194 log_write(vq->log_base,
2195 vq->log_addr +
2196 ((void __user *)used - (void __user *)vq->used),
2197 count * sizeof *used);
2198 }
2199 old = vq->last_used_idx;
2200 new = (vq->last_used_idx += count);
2201 /* If the driver never bothers to signal in a very long while,
2202 * used index might wrap around. If that happens, invalidate
2203 * signalled_used index we stored. TODO: make sure driver
2204 * signals at least once in 2^16 and remove this. */
2205 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2206 vq->signalled_used_valid = false;
2207 return 0;
2208 }
2209
2210 /* After we've used one of their buffers, we tell them about it. We'll then
2211 * want to notify the guest, using eventfd. */
2212 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2213 unsigned count)
2214 {
2215 int start, n, r;
2216
2217 start = vq->last_used_idx & (vq->num - 1);
2218 n = vq->num - start;
2219 if (n < count) {
2220 r = __vhost_add_used_n(vq, heads, n);
2221 if (r < 0)
2222 return r;
2223 heads += n;
2224 count -= n;
2225 }
2226 r = __vhost_add_used_n(vq, heads, count);
2227
2228 /* Make sure buffer is written before we update index. */
2229 smp_wmb();
2230 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2231 &vq->used->idx)) {
2232 vq_err(vq, "Failed to increment used idx");
2233 return -EFAULT;
2234 }
2235 if (unlikely(vq->log_used)) {
2236 /* Make sure used idx is seen before log. */
2237 smp_wmb();
2238 /* Log used index update. */
2239 log_write(vq->log_base,
2240 vq->log_addr + offsetof(struct vring_used, idx),
2241 sizeof vq->used->idx);
2242 if (vq->log_ctx)
2243 eventfd_signal(vq->log_ctx, 1);
2244 }
2245 return r;
2246 }
2247 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2248
2249 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2250 {
2251 __u16 old, new;
2252 __virtio16 event;
2253 bool v;
2254 /* Flush out used index updates. This is paired
2255 * with the barrier that the Guest executes when enabling
2256 * interrupts. */
2257 smp_mb();
2258
2259 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2260 unlikely(vq->avail_idx == vq->last_avail_idx))
2261 return true;
2262
2263 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2264 __virtio16 flags;
2265 if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
2266 vq_err(vq, "Failed to get flags");
2267 return true;
2268 }
2269 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2270 }
2271 old = vq->signalled_used;
2272 v = vq->signalled_used_valid;
2273 new = vq->signalled_used = vq->last_used_idx;
2274 vq->signalled_used_valid = true;
2275
2276 if (unlikely(!v))
2277 return true;
2278
2279 if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
2280 vq_err(vq, "Failed to get used event idx");
2281 return true;
2282 }
2283 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2284 }
2285
2286 /* This actually signals the guest, using eventfd. */
2287 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2288 {
2289 /* Signal the Guest tell them we used something up. */
2290 if (vq->call_ctx && vhost_notify(dev, vq))
2291 eventfd_signal(vq->call_ctx, 1);
2292 }
2293 EXPORT_SYMBOL_GPL(vhost_signal);
2294
2295 /* And here's the combo meal deal. Supersize me! */
2296 void vhost_add_used_and_signal(struct vhost_dev *dev,
2297 struct vhost_virtqueue *vq,
2298 unsigned int head, int len)
2299 {
2300 vhost_add_used(vq, head, len);
2301 vhost_signal(dev, vq);
2302 }
2303 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2304
2305 /* multi-buffer version of vhost_add_used_and_signal */
2306 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2307 struct vhost_virtqueue *vq,
2308 struct vring_used_elem *heads, unsigned count)
2309 {
2310 vhost_add_used_n(vq, heads, count);
2311 vhost_signal(dev, vq);
2312 }
2313 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2314
2315 /* return true if we're sure that avaiable ring is empty */
2316 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2317 {
2318 __virtio16 avail_idx;
2319 int r;
2320
2321 if (vq->avail_idx != vq->last_avail_idx)
2322 return false;
2323
2324 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2325 if (unlikely(r))
2326 return false;
2327 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2328
2329 return vq->avail_idx == vq->last_avail_idx;
2330 }
2331 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2332
2333 /* OK, now we need to know about added descriptors. */
2334 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2335 {
2336 __virtio16 avail_idx;
2337 int r;
2338
2339 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2340 return false;
2341 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2342 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2343 r = vhost_update_used_flags(vq);
2344 if (r) {
2345 vq_err(vq, "Failed to enable notification at %p: %d\n",
2346 &vq->used->flags, r);
2347 return false;
2348 }
2349 } else {
2350 r = vhost_update_avail_event(vq, vq->avail_idx);
2351 if (r) {
2352 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2353 vhost_avail_event(vq), r);
2354 return false;
2355 }
2356 }
2357 /* They could have slipped one in as we were doing that: make
2358 * sure it's written, then check again. */
2359 smp_mb();
2360 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2361 if (r) {
2362 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2363 &vq->avail->idx, r);
2364 return false;
2365 }
2366
2367 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2368 }
2369 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2370
2371 /* We don't need to be notified again. */
2372 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2373 {
2374 int r;
2375
2376 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2377 return;
2378 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2379 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2380 r = vhost_update_used_flags(vq);
2381 if (r)
2382 vq_err(vq, "Failed to enable notification at %p: %d\n",
2383 &vq->used->flags, r);
2384 }
2385 }
2386 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2387
2388 /* Create a new message. */
2389 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2390 {
2391 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2392 if (!node)
2393 return NULL;
2394
2395 /* Make sure all padding within the structure is initialized. */
2396 memset(&node->msg, 0, sizeof node->msg);
2397 node->vq = vq;
2398 node->msg.type = type;
2399 return node;
2400 }
2401 EXPORT_SYMBOL_GPL(vhost_new_msg);
2402
2403 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2404 struct vhost_msg_node *node)
2405 {
2406 spin_lock(&dev->iotlb_lock);
2407 list_add_tail(&node->node, head);
2408 spin_unlock(&dev->iotlb_lock);
2409
2410 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2411 }
2412 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2413
2414 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2415 struct list_head *head)
2416 {
2417 struct vhost_msg_node *node = NULL;
2418
2419 spin_lock(&dev->iotlb_lock);
2420 if (!list_empty(head)) {
2421 node = list_first_entry(head, struct vhost_msg_node,
2422 node);
2423 list_del(&node->node);
2424 }
2425 spin_unlock(&dev->iotlb_lock);
2426
2427 return node;
2428 }
2429 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2430
2431
2432 static int __init vhost_init(void)
2433 {
2434 return 0;
2435 }
2436
2437 static void __exit vhost_exit(void)
2438 {
2439 }
2440
2441 module_init(vhost_init);
2442 module_exit(vhost_exit);
2443
2444 MODULE_VERSION("0.0.1");
2445 MODULE_LICENSE("GPL v2");
2446 MODULE_AUTHOR("Michael S. Tsirkin");
2447 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
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