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Linux 4.16.11
[linux/fpc-iii.git] / drivers / vhost / vhost.c
blobbe6a4b6a76c6f3fabbae2f9d1b480f8f804c18de
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_USED);
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 if (!vq_log_access_ok(vq, vq->log_base))
1248 return 0;
1249
1250 /* Access validation occurs at prefetch time with IOTLB */
1251 if (vq->iotlb)
1252 return 1;
1253
1254 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1255 }
1256 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1257
1258 static struct vhost_umem *vhost_umem_alloc(void)
1259 {
1260 struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1261
1262 if (!umem)
1263 return NULL;
1264
1265 umem->umem_tree = RB_ROOT_CACHED;
1266 umem->numem = 0;
1267 INIT_LIST_HEAD(&umem->umem_list);
1268
1269 return umem;
1270 }
1271
1272 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1273 {
1274 struct vhost_memory mem, *newmem;
1275 struct vhost_memory_region *region;
1276 struct vhost_umem *newumem, *oldumem;
1277 unsigned long size = offsetof(struct vhost_memory, regions);
1278 int i;
1279
1280 if (copy_from_user(&mem, m, size))
1281 return -EFAULT;
1282 if (mem.padding)
1283 return -EOPNOTSUPP;
1284 if (mem.nregions > max_mem_regions)
1285 return -E2BIG;
1286 newmem = kvzalloc(size + mem.nregions * sizeof(*m->regions), GFP_KERNEL);
1287 if (!newmem)
1288 return -ENOMEM;
1289
1290 memcpy(newmem, &mem, size);
1291 if (copy_from_user(newmem->regions, m->regions,
1292 mem.nregions * sizeof *m->regions)) {
1293 kvfree(newmem);
1294 return -EFAULT;
1295 }
1296
1297 newumem = vhost_umem_alloc();
1298 if (!newumem) {
1299 kvfree(newmem);
1300 return -ENOMEM;
1301 }
1302
1303 for (region = newmem->regions;
1304 region < newmem->regions + mem.nregions;
1305 region++) {
1306 if (vhost_new_umem_range(newumem,
1307 region->guest_phys_addr,
1308 region->memory_size,
1309 region->guest_phys_addr +
1310 region->memory_size - 1,
1311 region->userspace_addr,
1312 VHOST_ACCESS_RW))
1313 goto err;
1314 }
1315
1316 if (!memory_access_ok(d, newumem, 0))
1317 goto err;
1318
1319 oldumem = d->umem;
1320 d->umem = newumem;
1321
1322 /* All memory accesses are done under some VQ mutex. */
1323 for (i = 0; i < d->nvqs; ++i) {
1324 mutex_lock(&d->vqs[i]->mutex);
1325 d->vqs[i]->umem = newumem;
1326 mutex_unlock(&d->vqs[i]->mutex);
1327 }
1328
1329 kvfree(newmem);
1330 vhost_umem_clean(oldumem);
1331 return 0;
1332
1333 err:
1334 vhost_umem_clean(newumem);
1335 kvfree(newmem);
1336 return -EFAULT;
1337 }
1338
1339 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
1340 {
1341 struct file *eventfp, *filep = NULL;
1342 bool pollstart = false, pollstop = false;
1343 struct eventfd_ctx *ctx = NULL;
1344 u32 __user *idxp = argp;
1345 struct vhost_virtqueue *vq;
1346 struct vhost_vring_state s;
1347 struct vhost_vring_file f;
1348 struct vhost_vring_addr a;
1349 u32 idx;
1350 long r;
1351
1352 r = get_user(idx, idxp);
1353 if (r < 0)
1354 return r;
1355 if (idx >= d->nvqs)
1356 return -ENOBUFS;
1357
1358 vq = d->vqs[idx];
1359
1360 mutex_lock(&vq->mutex);
1361
1362 switch (ioctl) {
1363 case VHOST_SET_VRING_NUM:
1364 /* Resizing ring with an active backend?
1365 * You don't want to do that. */
1366 if (vq->private_data) {
1367 r = -EBUSY;
1368 break;
1369 }
1370 if (copy_from_user(&s, argp, sizeof s)) {
1371 r = -EFAULT;
1372 break;
1373 }
1374 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1375 r = -EINVAL;
1376 break;
1377 }
1378 vq->num = s.num;
1379 break;
1380 case VHOST_SET_VRING_BASE:
1381 /* Moving base with an active backend?
1382 * You don't want to do that. */
1383 if (vq->private_data) {
1384 r = -EBUSY;
1385 break;
1386 }
1387 if (copy_from_user(&s, argp, sizeof s)) {
1388 r = -EFAULT;
1389 break;
1390 }
1391 if (s.num > 0xffff) {
1392 r = -EINVAL;
1393 break;
1394 }
1395 vq->last_avail_idx = s.num;
1396 /* Forget the cached index value. */
1397 vq->avail_idx = vq->last_avail_idx;
1398 break;
1399 case VHOST_GET_VRING_BASE:
1400 s.index = idx;
1401 s.num = vq->last_avail_idx;
1402 if (copy_to_user(argp, &s, sizeof s))
1403 r = -EFAULT;
1404 break;
1405 case VHOST_SET_VRING_ADDR:
1406 if (copy_from_user(&a, argp, sizeof a)) {
1407 r = -EFAULT;
1408 break;
1409 }
1410 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1411 r = -EOPNOTSUPP;
1412 break;
1413 }
1414 /* For 32bit, verify that the top 32bits of the user
1415 data are set to zero. */
1416 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1417 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1418 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1419 r = -EFAULT;
1420 break;
1421 }
1422
1423 /* Make sure it's safe to cast pointers to vring types. */
1424 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1425 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1426 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1427 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1428 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1429 r = -EINVAL;
1430 break;
1431 }
1432
1433 /* We only verify access here if backend is configured.
1434 * If it is not, we don't as size might not have been setup.
1435 * We will verify when backend is configured. */
1436 if (vq->private_data) {
1437 if (!vq_access_ok(vq, vq->num,
1438 (void __user *)(unsigned long)a.desc_user_addr,
1439 (void __user *)(unsigned long)a.avail_user_addr,
1440 (void __user *)(unsigned long)a.used_user_addr)) {
1441 r = -EINVAL;
1442 break;
1443 }
1444
1445 /* Also validate log access for used ring if enabled. */
1446 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1447 !log_access_ok(vq->log_base, a.log_guest_addr,
1448 sizeof *vq->used +
1449 vq->num * sizeof *vq->used->ring)) {
1450 r = -EINVAL;
1451 break;
1452 }
1453 }
1454
1455 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1456 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1457 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1458 vq->log_addr = a.log_guest_addr;
1459 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1460 break;
1461 case VHOST_SET_VRING_KICK:
1462 if (copy_from_user(&f, argp, sizeof f)) {
1463 r = -EFAULT;
1464 break;
1465 }
1466 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1467 if (IS_ERR(eventfp)) {
1468 r = PTR_ERR(eventfp);
1469 break;
1470 }
1471 if (eventfp != vq->kick) {
1472 pollstop = (filep = vq->kick) != NULL;
1473 pollstart = (vq->kick = eventfp) != NULL;
1474 } else
1475 filep = eventfp;
1476 break;
1477 case VHOST_SET_VRING_CALL:
1478 if (copy_from_user(&f, argp, sizeof f)) {
1479 r = -EFAULT;
1480 break;
1481 }
1482 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1483 if (IS_ERR(ctx)) {
1484 r = PTR_ERR(ctx);
1485 break;
1486 }
1487 swap(ctx, vq->call_ctx);
1488 break;
1489 case VHOST_SET_VRING_ERR:
1490 if (copy_from_user(&f, argp, sizeof f)) {
1491 r = -EFAULT;
1492 break;
1493 }
1494 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1495 if (IS_ERR(ctx)) {
1496 r = PTR_ERR(ctx);
1497 break;
1498 }
1499 swap(ctx, vq->error_ctx);
1500 break;
1501 case VHOST_SET_VRING_ENDIAN:
1502 r = vhost_set_vring_endian(vq, argp);
1503 break;
1504 case VHOST_GET_VRING_ENDIAN:
1505 r = vhost_get_vring_endian(vq, idx, argp);
1506 break;
1507 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1508 if (copy_from_user(&s, argp, sizeof(s))) {
1509 r = -EFAULT;
1510 break;
1511 }
1512 vq->busyloop_timeout = s.num;
1513 break;
1514 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1515 s.index = idx;
1516 s.num = vq->busyloop_timeout;
1517 if (copy_to_user(argp, &s, sizeof(s)))
1518 r = -EFAULT;
1519 break;
1520 default:
1521 r = -ENOIOCTLCMD;
1522 }
1523
1524 if (pollstop && vq->handle_kick)
1525 vhost_poll_stop(&vq->poll);
1526
1527 if (!IS_ERR_OR_NULL(ctx))
1528 eventfd_ctx_put(ctx);
1529 if (filep)
1530 fput(filep);
1531
1532 if (pollstart && vq->handle_kick)
1533 r = vhost_poll_start(&vq->poll, vq->kick);
1534
1535 mutex_unlock(&vq->mutex);
1536
1537 if (pollstop && vq->handle_kick)
1538 vhost_poll_flush(&vq->poll);
1539 return r;
1540 }
1541 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1542
1543 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1544 {
1545 struct vhost_umem *niotlb, *oiotlb;
1546 int i;
1547
1548 niotlb = vhost_umem_alloc();
1549 if (!niotlb)
1550 return -ENOMEM;
1551
1552 oiotlb = d->iotlb;
1553 d->iotlb = niotlb;
1554
1555 for (i = 0; i < d->nvqs; ++i) {
1556 mutex_lock(&d->vqs[i]->mutex);
1557 d->vqs[i]->iotlb = niotlb;
1558 mutex_unlock(&d->vqs[i]->mutex);
1559 }
1560
1561 vhost_umem_clean(oiotlb);
1562
1563 return 0;
1564 }
1565 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1566
1567 /* Caller must have device mutex */
1568 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1569 {
1570 struct eventfd_ctx *ctx;
1571 u64 p;
1572 long r;
1573 int i, fd;
1574
1575 /* If you are not the owner, you can become one */
1576 if (ioctl == VHOST_SET_OWNER) {
1577 r = vhost_dev_set_owner(d);
1578 goto done;
1579 }
1580
1581 /* You must be the owner to do anything else */
1582 r = vhost_dev_check_owner(d);
1583 if (r)
1584 goto done;
1585
1586 switch (ioctl) {
1587 case VHOST_SET_MEM_TABLE:
1588 r = vhost_set_memory(d, argp);
1589 break;
1590 case VHOST_SET_LOG_BASE:
1591 if (copy_from_user(&p, argp, sizeof p)) {
1592 r = -EFAULT;
1593 break;
1594 }
1595 if ((u64)(unsigned long)p != p) {
1596 r = -EFAULT;
1597 break;
1598 }
1599 for (i = 0; i < d->nvqs; ++i) {
1600 struct vhost_virtqueue *vq;
1601 void __user *base = (void __user *)(unsigned long)p;
1602 vq = d->vqs[i];
1603 mutex_lock(&vq->mutex);
1604 /* If ring is inactive, will check when it's enabled. */
1605 if (vq->private_data && !vq_log_access_ok(vq, base))
1606 r = -EFAULT;
1607 else
1608 vq->log_base = base;
1609 mutex_unlock(&vq->mutex);
1610 }
1611 break;
1612 case VHOST_SET_LOG_FD:
1613 r = get_user(fd, (int __user *)argp);
1614 if (r < 0)
1615 break;
1616 ctx = fd == -1 ? NULL : eventfd_ctx_fdget(fd);
1617 if (IS_ERR(ctx)) {
1618 r = PTR_ERR(ctx);
1619 break;
1620 }
1621 swap(ctx, d->log_ctx);
1622 for (i = 0; i < d->nvqs; ++i) {
1623 mutex_lock(&d->vqs[i]->mutex);
1624 d->vqs[i]->log_ctx = d->log_ctx;
1625 mutex_unlock(&d->vqs[i]->mutex);
1626 }
1627 if (ctx)
1628 eventfd_ctx_put(ctx);
1629 break;
1630 default:
1631 r = -ENOIOCTLCMD;
1632 break;
1633 }
1634 done:
1635 return r;
1636 }
1637 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1638
1639 /* TODO: This is really inefficient. We need something like get_user()
1640 * (instruction directly accesses the data, with an exception table entry
1641 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1642 */
1643 static int set_bit_to_user(int nr, void __user *addr)
1644 {
1645 unsigned long log = (unsigned long)addr;
1646 struct page *page;
1647 void *base;
1648 int bit = nr + (log % PAGE_SIZE) * 8;
1649 int r;
1650
1651 r = get_user_pages_fast(log, 1, 1, &page);
1652 if (r < 0)
1653 return r;
1654 BUG_ON(r != 1);
1655 base = kmap_atomic(page);
1656 set_bit(bit, base);
1657 kunmap_atomic(base);
1658 set_page_dirty_lock(page);
1659 put_page(page);
1660 return 0;
1661 }
1662
1663 static int log_write(void __user *log_base,
1664 u64 write_address, u64 write_length)
1665 {
1666 u64 write_page = write_address / VHOST_PAGE_SIZE;
1667 int r;
1668
1669 if (!write_length)
1670 return 0;
1671 write_length += write_address % VHOST_PAGE_SIZE;
1672 for (;;) {
1673 u64 base = (u64)(unsigned long)log_base;
1674 u64 log = base + write_page / 8;
1675 int bit = write_page % 8;
1676 if ((u64)(unsigned long)log != log)
1677 return -EFAULT;
1678 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1679 if (r < 0)
1680 return r;
1681 if (write_length <= VHOST_PAGE_SIZE)
1682 break;
1683 write_length -= VHOST_PAGE_SIZE;
1684 write_page += 1;
1685 }
1686 return r;
1687 }
1688
1689 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1690 unsigned int log_num, u64 len)
1691 {
1692 int i, r;
1693
1694 /* Make sure data written is seen before log. */
1695 smp_wmb();
1696 for (i = 0; i < log_num; ++i) {
1697 u64 l = min(log[i].len, len);
1698 r = log_write(vq->log_base, log[i].addr, l);
1699 if (r < 0)
1700 return r;
1701 len -= l;
1702 if (!len) {
1703 if (vq->log_ctx)
1704 eventfd_signal(vq->log_ctx, 1);
1705 return 0;
1706 }
1707 }
1708 /* Length written exceeds what we have stored. This is a bug. */
1709 BUG();
1710 return 0;
1711 }
1712 EXPORT_SYMBOL_GPL(vhost_log_write);
1713
1714 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1715 {
1716 void __user *used;
1717 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1718 &vq->used->flags) < 0)
1719 return -EFAULT;
1720 if (unlikely(vq->log_used)) {
1721 /* Make sure the flag is seen before log. */
1722 smp_wmb();
1723 /* Log used flag write. */
1724 used = &vq->used->flags;
1725 log_write(vq->log_base, vq->log_addr +
1726 (used - (void __user *)vq->used),
1727 sizeof vq->used->flags);
1728 if (vq->log_ctx)
1729 eventfd_signal(vq->log_ctx, 1);
1730 }
1731 return 0;
1732 }
1733
1734 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1735 {
1736 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1737 vhost_avail_event(vq)))
1738 return -EFAULT;
1739 if (unlikely(vq->log_used)) {
1740 void __user *used;
1741 /* Make sure the event is seen before log. */
1742 smp_wmb();
1743 /* Log avail event write */
1744 used = vhost_avail_event(vq);
1745 log_write(vq->log_base, vq->log_addr +
1746 (used - (void __user *)vq->used),
1747 sizeof *vhost_avail_event(vq));
1748 if (vq->log_ctx)
1749 eventfd_signal(vq->log_ctx, 1);
1750 }
1751 return 0;
1752 }
1753
1754 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1755 {
1756 __virtio16 last_used_idx;
1757 int r;
1758 bool is_le = vq->is_le;
1759
1760 if (!vq->private_data)
1761 return 0;
1762
1763 vhost_init_is_le(vq);
1764
1765 r = vhost_update_used_flags(vq);
1766 if (r)
1767 goto err;
1768 vq->signalled_used_valid = false;
1769 if (!vq->iotlb &&
1770 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1771 r = -EFAULT;
1772 goto err;
1773 }
1774 r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
1775 if (r) {
1776 vq_err(vq, "Can't access used idx at %p\n",
1777 &vq->used->idx);
1778 goto err;
1779 }
1780 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1781 return 0;
1782
1783 err:
1784 vq->is_le = is_le;
1785 return r;
1786 }
1787 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1788
1789 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1790 struct iovec iov[], int iov_size, int access)
1791 {
1792 const struct vhost_umem_node *node;
1793 struct vhost_dev *dev = vq->dev;
1794 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1795 struct iovec *_iov;
1796 u64 s = 0;
1797 int ret = 0;
1798
1799 while ((u64)len > s) {
1800 u64 size;
1801 if (unlikely(ret >= iov_size)) {
1802 ret = -ENOBUFS;
1803 break;
1804 }
1805
1806 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1807 addr, addr + len - 1);
1808 if (node == NULL || node->start > addr) {
1809 if (umem != dev->iotlb) {
1810 ret = -EFAULT;
1811 break;
1812 }
1813 ret = -EAGAIN;
1814 break;
1815 } else if (!(node->perm & access)) {
1816 ret = -EPERM;
1817 break;
1818 }
1819
1820 _iov = iov + ret;
1821 size = node->size - addr + node->start;
1822 _iov->iov_len = min((u64)len - s, size);
1823 _iov->iov_base = (void __user *)(unsigned long)
1824 (node->userspace_addr + addr - node->start);
1825 s += size;
1826 addr += size;
1827 ++ret;
1828 }
1829
1830 if (ret == -EAGAIN)
1831 vhost_iotlb_miss(vq, addr, access);
1832 return ret;
1833 }
1834
1835 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1836 * function returns the next descriptor in the chain,
1837 * or -1U if we're at the end. */
1838 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1839 {
1840 unsigned int next;
1841
1842 /* If this descriptor says it doesn't chain, we're done. */
1843 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1844 return -1U;
1845
1846 /* Check they're not leading us off end of descriptors. */
1847 next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
1848 return next;
1849 }
1850
1851 static int get_indirect(struct vhost_virtqueue *vq,
1852 struct iovec iov[], unsigned int iov_size,
1853 unsigned int *out_num, unsigned int *in_num,
1854 struct vhost_log *log, unsigned int *log_num,
1855 struct vring_desc *indirect)
1856 {
1857 struct vring_desc desc;
1858 unsigned int i = 0, count, found = 0;
1859 u32 len = vhost32_to_cpu(vq, indirect->len);
1860 struct iov_iter from;
1861 int ret, access;
1862
1863 /* Sanity check */
1864 if (unlikely(len % sizeof desc)) {
1865 vq_err(vq, "Invalid length in indirect descriptor: "
1866 "len 0x%llx not multiple of 0x%zx\n",
1867 (unsigned long long)len,
1868 sizeof desc);
1869 return -EINVAL;
1870 }
1871
1872 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1873 UIO_MAXIOV, VHOST_ACCESS_RO);
1874 if (unlikely(ret < 0)) {
1875 if (ret != -EAGAIN)
1876 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1877 return ret;
1878 }
1879 iov_iter_init(&from, READ, vq->indirect, ret, len);
1880
1881 /* We will use the result as an address to read from, so most
1882 * architectures only need a compiler barrier here. */
1883 read_barrier_depends();
1884
1885 count = len / sizeof desc;
1886 /* Buffers are chained via a 16 bit next field, so
1887 * we can have at most 2^16 of these. */
1888 if (unlikely(count > USHRT_MAX + 1)) {
1889 vq_err(vq, "Indirect buffer length too big: %d\n",
1890 indirect->len);
1891 return -E2BIG;
1892 }
1893
1894 do {
1895 unsigned iov_count = *in_num + *out_num;
1896 if (unlikely(++found > count)) {
1897 vq_err(vq, "Loop detected: last one at %u "
1898 "indirect size %u\n",
1899 i, count);
1900 return -EINVAL;
1901 }
1902 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1903 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1904 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1905 return -EINVAL;
1906 }
1907 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1908 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1909 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1910 return -EINVAL;
1911 }
1912
1913 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1914 access = VHOST_ACCESS_WO;
1915 else
1916 access = VHOST_ACCESS_RO;
1917
1918 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1919 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1920 iov_size - iov_count, access);
1921 if (unlikely(ret < 0)) {
1922 if (ret != -EAGAIN)
1923 vq_err(vq, "Translation failure %d indirect idx %d\n",
1924 ret, i);
1925 return ret;
1926 }
1927 /* If this is an input descriptor, increment that count. */
1928 if (access == VHOST_ACCESS_WO) {
1929 *in_num += ret;
1930 if (unlikely(log)) {
1931 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1932 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1933 ++*log_num;
1934 }
1935 } else {
1936 /* If it's an output descriptor, they're all supposed
1937 * to come before any input descriptors. */
1938 if (unlikely(*in_num)) {
1939 vq_err(vq, "Indirect descriptor "
1940 "has out after in: idx %d\n", i);
1941 return -EINVAL;
1942 }
1943 *out_num += ret;
1944 }
1945 } while ((i = next_desc(vq, &desc)) != -1);
1946 return 0;
1947 }
1948
1949 /* This looks in the virtqueue and for the first available buffer, and converts
1950 * it to an iovec for convenient access. Since descriptors consist of some
1951 * number of output then some number of input descriptors, it's actually two
1952 * iovecs, but we pack them into one and note how many of each there were.
1953 *
1954 * This function returns the descriptor number found, or vq->num (which is
1955 * never a valid descriptor number) if none was found. A negative code is
1956 * returned on error. */
1957 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1958 struct iovec iov[], unsigned int iov_size,
1959 unsigned int *out_num, unsigned int *in_num,
1960 struct vhost_log *log, unsigned int *log_num)
1961 {
1962 struct vring_desc desc;
1963 unsigned int i, head, found = 0;
1964 u16 last_avail_idx;
1965 __virtio16 avail_idx;
1966 __virtio16 ring_head;
1967 int ret, access;
1968
1969 /* Check it isn't doing very strange things with descriptor numbers. */
1970 last_avail_idx = vq->last_avail_idx;
1971
1972 if (vq->avail_idx == vq->last_avail_idx) {
1973 if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
1974 vq_err(vq, "Failed to access avail idx at %p\n",
1975 &vq->avail->idx);
1976 return -EFAULT;
1977 }
1978 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1979
1980 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1981 vq_err(vq, "Guest moved used index from %u to %u",
1982 last_avail_idx, vq->avail_idx);
1983 return -EFAULT;
1984 }
1985
1986 /* If there's nothing new since last we looked, return
1987 * invalid.
1988 */
1989 if (vq->avail_idx == last_avail_idx)
1990 return vq->num;
1991
1992 /* Only get avail ring entries after they have been
1993 * exposed by guest.
1994 */
1995 smp_rmb();
1996 }
1997
1998 /* Grab the next descriptor number they're advertising, and increment
1999 * the index we've seen. */
2000 if (unlikely(vhost_get_avail(vq, ring_head,
2001 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
2002 vq_err(vq, "Failed to read head: idx %d address %p\n",
2003 last_avail_idx,
2004 &vq->avail->ring[last_avail_idx % vq->num]);
2005 return -EFAULT;
2006 }
2007
2008 head = vhost16_to_cpu(vq, ring_head);
2009
2010 /* If their number is silly, that's an error. */
2011 if (unlikely(head >= vq->num)) {
2012 vq_err(vq, "Guest says index %u > %u is available",
2013 head, vq->num);
2014 return -EINVAL;
2015 }
2016
2017 /* When we start there are none of either input nor output. */
2018 *out_num = *in_num = 0;
2019 if (unlikely(log))
2020 *log_num = 0;
2021
2022 i = head;
2023 do {
2024 unsigned iov_count = *in_num + *out_num;
2025 if (unlikely(i >= vq->num)) {
2026 vq_err(vq, "Desc index is %u > %u, head = %u",
2027 i, vq->num, head);
2028 return -EINVAL;
2029 }
2030 if (unlikely(++found > vq->num)) {
2031 vq_err(vq, "Loop detected: last one at %u "
2032 "vq size %u head %u\n",
2033 i, vq->num, head);
2034 return -EINVAL;
2035 }
2036 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
2037 sizeof desc);
2038 if (unlikely(ret)) {
2039 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2040 i, vq->desc + i);
2041 return -EFAULT;
2042 }
2043 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2044 ret = get_indirect(vq, iov, iov_size,
2045 out_num, in_num,
2046 log, log_num, &desc);
2047 if (unlikely(ret < 0)) {
2048 if (ret != -EAGAIN)
2049 vq_err(vq, "Failure detected "
2050 "in indirect descriptor at idx %d\n", i);
2051 return ret;
2052 }
2053 continue;
2054 }
2055
2056 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2057 access = VHOST_ACCESS_WO;
2058 else
2059 access = VHOST_ACCESS_RO;
2060 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2061 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2062 iov_size - iov_count, access);
2063 if (unlikely(ret < 0)) {
2064 if (ret != -EAGAIN)
2065 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2066 ret, i);
2067 return ret;
2068 }
2069 if (access == VHOST_ACCESS_WO) {
2070 /* If this is an input descriptor,
2071 * increment that count. */
2072 *in_num += ret;
2073 if (unlikely(log)) {
2074 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2075 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2076 ++*log_num;
2077 }
2078 } else {
2079 /* If it's an output descriptor, they're all supposed
2080 * to come before any input descriptors. */
2081 if (unlikely(*in_num)) {
2082 vq_err(vq, "Descriptor has out after in: "
2083 "idx %d\n", i);
2084 return -EINVAL;
2085 }
2086 *out_num += ret;
2087 }
2088 } while ((i = next_desc(vq, &desc)) != -1);
2089
2090 /* On success, increment avail index. */
2091 vq->last_avail_idx++;
2092
2093 /* Assume notifications from guest are disabled at this point,
2094 * if they aren't we would need to update avail_event index. */
2095 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2096 return head;
2097 }
2098 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2099
2100 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2101 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2102 {
2103 vq->last_avail_idx -= n;
2104 }
2105 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2106
2107 /* After we've used one of their buffers, we tell them about it. We'll then
2108 * want to notify the guest, using eventfd. */
2109 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2110 {
2111 struct vring_used_elem heads = {
2112 cpu_to_vhost32(vq, head),
2113 cpu_to_vhost32(vq, len)
2114 };
2115
2116 return vhost_add_used_n(vq, &heads, 1);
2117 }
2118 EXPORT_SYMBOL_GPL(vhost_add_used);
2119
2120 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2121 struct vring_used_elem *heads,
2122 unsigned count)
2123 {
2124 struct vring_used_elem __user *used;
2125 u16 old, new;
2126 int start;
2127
2128 start = vq->last_used_idx & (vq->num - 1);
2129 used = vq->used->ring + start;
2130 if (count == 1) {
2131 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2132 vq_err(vq, "Failed to write used id");
2133 return -EFAULT;
2134 }
2135 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2136 vq_err(vq, "Failed to write used len");
2137 return -EFAULT;
2138 }
2139 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2140 vq_err(vq, "Failed to write used");
2141 return -EFAULT;
2142 }
2143 if (unlikely(vq->log_used)) {
2144 /* Make sure data is seen before log. */
2145 smp_wmb();
2146 /* Log used ring entry write. */
2147 log_write(vq->log_base,
2148 vq->log_addr +
2149 ((void __user *)used - (void __user *)vq->used),
2150 count * sizeof *used);
2151 }
2152 old = vq->last_used_idx;
2153 new = (vq->last_used_idx += count);
2154 /* If the driver never bothers to signal in a very long while,
2155 * used index might wrap around. If that happens, invalidate
2156 * signalled_used index we stored. TODO: make sure driver
2157 * signals at least once in 2^16 and remove this. */
2158 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2159 vq->signalled_used_valid = false;
2160 return 0;
2161 }
2162
2163 /* After we've used one of their buffers, we tell them about it. We'll then
2164 * want to notify the guest, using eventfd. */
2165 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2166 unsigned count)
2167 {
2168 int start, n, r;
2169
2170 start = vq->last_used_idx & (vq->num - 1);
2171 n = vq->num - start;
2172 if (n < count) {
2173 r = __vhost_add_used_n(vq, heads, n);
2174 if (r < 0)
2175 return r;
2176 heads += n;
2177 count -= n;
2178 }
2179 r = __vhost_add_used_n(vq, heads, count);
2180
2181 /* Make sure buffer is written before we update index. */
2182 smp_wmb();
2183 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2184 &vq->used->idx)) {
2185 vq_err(vq, "Failed to increment used idx");
2186 return -EFAULT;
2187 }
2188 if (unlikely(vq->log_used)) {
2189 /* Log used index update. */
2190 log_write(vq->log_base,
2191 vq->log_addr + offsetof(struct vring_used, idx),
2192 sizeof vq->used->idx);
2193 if (vq->log_ctx)
2194 eventfd_signal(vq->log_ctx, 1);
2195 }
2196 return r;
2197 }
2198 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2199
2200 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2201 {
2202 __u16 old, new;
2203 __virtio16 event;
2204 bool v;
2205 /* Flush out used index updates. This is paired
2206 * with the barrier that the Guest executes when enabling
2207 * interrupts. */
2208 smp_mb();
2209
2210 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2211 unlikely(vq->avail_idx == vq->last_avail_idx))
2212 return true;
2213
2214 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2215 __virtio16 flags;
2216 if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
2217 vq_err(vq, "Failed to get flags");
2218 return true;
2219 }
2220 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2221 }
2222 old = vq->signalled_used;
2223 v = vq->signalled_used_valid;
2224 new = vq->signalled_used = vq->last_used_idx;
2225 vq->signalled_used_valid = true;
2226
2227 if (unlikely(!v))
2228 return true;
2229
2230 if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
2231 vq_err(vq, "Failed to get used event idx");
2232 return true;
2233 }
2234 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2235 }
2236
2237 /* This actually signals the guest, using eventfd. */
2238 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2239 {
2240 /* Signal the Guest tell them we used something up. */
2241 if (vq->call_ctx && vhost_notify(dev, vq))
2242 eventfd_signal(vq->call_ctx, 1);
2243 }
2244 EXPORT_SYMBOL_GPL(vhost_signal);
2245
2246 /* And here's the combo meal deal. Supersize me! */
2247 void vhost_add_used_and_signal(struct vhost_dev *dev,
2248 struct vhost_virtqueue *vq,
2249 unsigned int head, int len)
2250 {
2251 vhost_add_used(vq, head, len);
2252 vhost_signal(dev, vq);
2253 }
2254 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2255
2256 /* multi-buffer version of vhost_add_used_and_signal */
2257 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2258 struct vhost_virtqueue *vq,
2259 struct vring_used_elem *heads, unsigned count)
2260 {
2261 vhost_add_used_n(vq, heads, count);
2262 vhost_signal(dev, vq);
2263 }
2264 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2265
2266 /* return true if we're sure that avaiable ring is empty */
2267 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2268 {
2269 __virtio16 avail_idx;
2270 int r;
2271
2272 if (vq->avail_idx != vq->last_avail_idx)
2273 return false;
2274
2275 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2276 if (unlikely(r))
2277 return false;
2278 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2279
2280 return vq->avail_idx == vq->last_avail_idx;
2281 }
2282 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2283
2284 /* OK, now we need to know about added descriptors. */
2285 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2286 {
2287 __virtio16 avail_idx;
2288 int r;
2289
2290 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2291 return false;
2292 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2293 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2294 r = vhost_update_used_flags(vq);
2295 if (r) {
2296 vq_err(vq, "Failed to enable notification at %p: %d\n",
2297 &vq->used->flags, r);
2298 return false;
2299 }
2300 } else {
2301 r = vhost_update_avail_event(vq, vq->avail_idx);
2302 if (r) {
2303 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2304 vhost_avail_event(vq), r);
2305 return false;
2306 }
2307 }
2308 /* They could have slipped one in as we were doing that: make
2309 * sure it's written, then check again. */
2310 smp_mb();
2311 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2312 if (r) {
2313 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2314 &vq->avail->idx, r);
2315 return false;
2316 }
2317
2318 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2319 }
2320 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2321
2322 /* We don't need to be notified again. */
2323 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2324 {
2325 int r;
2326
2327 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2328 return;
2329 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2330 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2331 r = vhost_update_used_flags(vq);
2332 if (r)
2333 vq_err(vq, "Failed to enable notification at %p: %d\n",
2334 &vq->used->flags, r);
2335 }
2336 }
2337 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2338
2339 /* Create a new message. */
2340 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2341 {
2342 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2343 if (!node)
2344 return NULL;
2345 node->vq = vq;
2346 node->msg.type = type;
2347 return node;
2348 }
2349 EXPORT_SYMBOL_GPL(vhost_new_msg);
2350
2351 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2352 struct vhost_msg_node *node)
2353 {
2354 spin_lock(&dev->iotlb_lock);
2355 list_add_tail(&node->node, head);
2356 spin_unlock(&dev->iotlb_lock);
2357
2358 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2359 }
2360 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2361
2362 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2363 struct list_head *head)
2364 {
2365 struct vhost_msg_node *node = NULL;
2366
2367 spin_lock(&dev->iotlb_lock);
2368 if (!list_empty(head)) {
2369 node = list_first_entry(head, struct vhost_msg_node,
2370 node);
2371 list_del(&node->node);
2372 }
2373 spin_unlock(&dev->iotlb_lock);
2374
2375 return node;
2376 }
2377 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2378
2379
2380 static int __init vhost_init(void)
2381 {
2382 return 0;
2383 }
2384
2385 static void __exit vhost_exit(void)
2386 {
2387 }
2388
2389 module_init(vhost_init);
2390 module_exit(vhost_exit);
2391
2392 MODULE_VERSION("0.0.1");
2393 MODULE_LICENSE("GPL v2");
2394 MODULE_AUTHOR("Michael S. Tsirkin");
2395 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
Linux with added FPC-III support