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[mirror_ubuntu-artful-kernel.git] / drivers / vhost / vhost.c
1 /* Copyright (C) 2009 Red Hat, Inc.
2 * Copyright (C) 2006 Rusty Russell IBM Corporation
3 *
4 * Author: Michael S. Tsirkin <mst@redhat.com>
5 *
6 * Inspiration, some code, and most witty comments come from
7 * Documentation/virtual/lguest/lguest.c, by Rusty Russell
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2.
10 *
11 * Generic code for virtio server in host kernel.
12 */
13
14 #include <linux/eventfd.h>
15 #include <linux/vhost.h>
16 #include <linux/uio.h>
17 #include <linux/mm.h>
18 #include <linux/mmu_context.h>
19 #include <linux/miscdevice.h>
20 #include <linux/mutex.h>
21 #include <linux/poll.h>
22 #include <linux/file.h>
23 #include <linux/highmem.h>
24 #include <linux/slab.h>
25 #include <linux/vmalloc.h>
26 #include <linux/kthread.h>
27 #include <linux/cgroup.h>
28 #include <linux/module.h>
29 #include <linux/sort.h>
30 #include <linux/sched/mm.h>
31 #include <linux/sched/signal.h>
32 #include <linux/interval_tree_generic.h>
33
34 #include "vhost.h"
35
36 static ushort max_mem_regions = 64;
37 module_param(max_mem_regions, ushort, 0444);
38 MODULE_PARM_DESC(max_mem_regions,
39 "Maximum number of memory regions in memory map. (default: 64)");
40 static int max_iotlb_entries = 2048;
41 module_param(max_iotlb_entries, int, 0444);
42 MODULE_PARM_DESC(max_iotlb_entries,
43 "Maximum number of iotlb entries. (default: 2048)");
44
45 enum {
46 VHOST_MEMORY_F_LOG = 0x1,
47 };
48
49 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
50 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
51
52 INTERVAL_TREE_DEFINE(struct vhost_umem_node,
53 rb, __u64, __subtree_last,
54 START, LAST, static inline, vhost_umem_interval_tree);
55
56 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
57 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
58 {
59 vq->user_be = !virtio_legacy_is_little_endian();
60 }
61
62 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
63 {
64 vq->user_be = true;
65 }
66
67 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
68 {
69 vq->user_be = false;
70 }
71
72 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
73 {
74 struct vhost_vring_state s;
75
76 if (vq->private_data)
77 return -EBUSY;
78
79 if (copy_from_user(&s, argp, sizeof(s)))
80 return -EFAULT;
81
82 if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
83 s.num != VHOST_VRING_BIG_ENDIAN)
84 return -EINVAL;
85
86 if (s.num == VHOST_VRING_BIG_ENDIAN)
87 vhost_enable_cross_endian_big(vq);
88 else
89 vhost_enable_cross_endian_little(vq);
90
91 return 0;
92 }
93
94 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
95 int __user *argp)
96 {
97 struct vhost_vring_state s = {
98 .index = idx,
99 .num = vq->user_be
100 };
101
102 if (copy_to_user(argp, &s, sizeof(s)))
103 return -EFAULT;
104
105 return 0;
106 }
107
108 static void vhost_init_is_le(struct vhost_virtqueue *vq)
109 {
110 /* Note for legacy virtio: user_be is initialized at reset time
111 * according to the host endianness. If userspace does not set an
112 * explicit endianness, the default behavior is native endian, as
113 * expected by legacy virtio.
114 */
115 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
116 }
117 #else
118 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
119 {
120 }
121
122 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
123 {
124 return -ENOIOCTLCMD;
125 }
126
127 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
128 int __user *argp)
129 {
130 return -ENOIOCTLCMD;
131 }
132
133 static void vhost_init_is_le(struct vhost_virtqueue *vq)
134 {
135 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
136 || virtio_legacy_is_little_endian();
137 }
138 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
139
140 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
141 {
142 vhost_init_is_le(vq);
143 }
144
145 struct vhost_flush_struct {
146 struct vhost_work work;
147 struct completion wait_event;
148 };
149
150 static void vhost_flush_work(struct vhost_work *work)
151 {
152 struct vhost_flush_struct *s;
153
154 s = container_of(work, struct vhost_flush_struct, work);
155 complete(&s->wait_event);
156 }
157
158 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
159 poll_table *pt)
160 {
161 struct vhost_poll *poll;
162
163 poll = container_of(pt, struct vhost_poll, table);
164 poll->wqh = wqh;
165 add_wait_queue(wqh, &poll->wait);
166 }
167
168 static int vhost_poll_wakeup(wait_queue_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 (!((unsigned long)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 init_waitqueue_head(&work->done);
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 unsigned long 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 unsigned long mask;
207 int ret = 0;
208
209 if (poll->wqh)
210 return 0;
211
212 mask = file->f_op->poll(file, &poll->table);
213 if (mask)
214 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
215 if (mask & POLLERR) {
216 if (poll->wqh)
217 remove_wait_queue(poll->wqh, &poll->wait);
218 ret = -EINVAL;
219 }
220
221 return ret;
222 }
223 EXPORT_SYMBOL_GPL(vhost_poll_start);
224
225 /* Stop polling a file. After this function returns, it becomes safe to drop the
226 * file reference. You must also flush afterwards. */
227 void vhost_poll_stop(struct vhost_poll *poll)
228 {
229 if (poll->wqh) {
230 remove_wait_queue(poll->wqh, &poll->wait);
231 poll->wqh = NULL;
232 }
233 }
234 EXPORT_SYMBOL_GPL(vhost_poll_stop);
235
236 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
237 {
238 struct vhost_flush_struct flush;
239
240 if (dev->worker) {
241 init_completion(&flush.wait_event);
242 vhost_work_init(&flush.work, vhost_flush_work);
243
244 vhost_work_queue(dev, &flush.work);
245 wait_for_completion(&flush.wait_event);
246 }
247 }
248 EXPORT_SYMBOL_GPL(vhost_work_flush);
249
250 /* Flush any work that has been scheduled. When calling this, don't hold any
251 * locks that are also used by the callback. */
252 void vhost_poll_flush(struct vhost_poll *poll)
253 {
254 vhost_work_flush(poll->dev, &poll->work);
255 }
256 EXPORT_SYMBOL_GPL(vhost_poll_flush);
257
258 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
259 {
260 if (!dev->worker)
261 return;
262
263 if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
264 /* We can only add the work to the list after we're
265 * sure it was not in the list.
266 * test_and_set_bit() implies a memory barrier.
267 */
268 llist_add(&work->node, &dev->work_list);
269 wake_up_process(dev->worker);
270 }
271 }
272 EXPORT_SYMBOL_GPL(vhost_work_queue);
273
274 /* A lockless hint for busy polling code to exit the loop */
275 bool vhost_has_work(struct vhost_dev *dev)
276 {
277 return !llist_empty(&dev->work_list);
278 }
279 EXPORT_SYMBOL_GPL(vhost_has_work);
280
281 void vhost_poll_queue(struct vhost_poll *poll)
282 {
283 vhost_work_queue(poll->dev, &poll->work);
284 }
285 EXPORT_SYMBOL_GPL(vhost_poll_queue);
286
287 static void vhost_vq_reset(struct vhost_dev *dev,
288 struct vhost_virtqueue *vq)
289 {
290 vq->num = 1;
291 vq->desc = NULL;
292 vq->avail = NULL;
293 vq->used = NULL;
294 vq->last_avail_idx = 0;
295 vq->last_used_event = 0;
296 vq->avail_idx = 0;
297 vq->last_used_idx = 0;
298 vq->signalled_used = 0;
299 vq->signalled_used_valid = false;
300 vq->used_flags = 0;
301 vq->log_used = false;
302 vq->log_addr = -1ull;
303 vq->private_data = NULL;
304 vq->acked_features = 0;
305 vq->log_base = NULL;
306 vq->error_ctx = NULL;
307 vq->error = NULL;
308 vq->kick = NULL;
309 vq->call_ctx = NULL;
310 vq->call = NULL;
311 vq->log_ctx = NULL;
312 vhost_reset_is_le(vq);
313 vhost_disable_cross_endian(vq);
314 vq->busyloop_timeout = 0;
315 vq->umem = NULL;
316 vq->iotlb = NULL;
317 }
318
319 static int vhost_worker(void *data)
320 {
321 struct vhost_dev *dev = data;
322 struct vhost_work *work, *work_next;
323 struct llist_node *node;
324 mm_segment_t oldfs = get_fs();
325
326 set_fs(USER_DS);
327 use_mm(dev->mm);
328
329 for (;;) {
330 /* mb paired w/ kthread_stop */
331 set_current_state(TASK_INTERRUPTIBLE);
332
333 if (kthread_should_stop()) {
334 __set_current_state(TASK_RUNNING);
335 break;
336 }
337
338 node = llist_del_all(&dev->work_list);
339 if (!node)
340 schedule();
341
342 node = llist_reverse_order(node);
343 /* make sure flag is seen after deletion */
344 smp_wmb();
345 llist_for_each_entry_safe(work, work_next, node, node) {
346 clear_bit(VHOST_WORK_QUEUED, &work->flags);
347 __set_current_state(TASK_RUNNING);
348 work->fn(work);
349 if (need_resched())
350 schedule();
351 }
352 }
353 unuse_mm(dev->mm);
354 set_fs(oldfs);
355 return 0;
356 }
357
358 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
359 {
360 kfree(vq->indirect);
361 vq->indirect = NULL;
362 kfree(vq->log);
363 vq->log = NULL;
364 kfree(vq->heads);
365 vq->heads = NULL;
366 }
367
368 /* Helper to allocate iovec buffers for all vqs. */
369 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
370 {
371 struct vhost_virtqueue *vq;
372 int i;
373
374 for (i = 0; i < dev->nvqs; ++i) {
375 vq = dev->vqs[i];
376 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
377 GFP_KERNEL);
378 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
379 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
380 if (!vq->indirect || !vq->log || !vq->heads)
381 goto err_nomem;
382 }
383 return 0;
384
385 err_nomem:
386 for (; i >= 0; --i)
387 vhost_vq_free_iovecs(dev->vqs[i]);
388 return -ENOMEM;
389 }
390
391 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
392 {
393 int i;
394
395 for (i = 0; i < dev->nvqs; ++i)
396 vhost_vq_free_iovecs(dev->vqs[i]);
397 }
398
399 void vhost_dev_init(struct vhost_dev *dev,
400 struct vhost_virtqueue **vqs, int nvqs)
401 {
402 struct vhost_virtqueue *vq;
403 int i;
404
405 dev->vqs = vqs;
406 dev->nvqs = nvqs;
407 mutex_init(&dev->mutex);
408 dev->log_ctx = NULL;
409 dev->log_file = NULL;
410 dev->umem = NULL;
411 dev->iotlb = NULL;
412 dev->mm = NULL;
413 dev->worker = NULL;
414 init_llist_head(&dev->work_list);
415 init_waitqueue_head(&dev->wait);
416 INIT_LIST_HEAD(&dev->read_list);
417 INIT_LIST_HEAD(&dev->pending_list);
418 spin_lock_init(&dev->iotlb_lock);
419
420
421 for (i = 0; i < dev->nvqs; ++i) {
422 vq = dev->vqs[i];
423 vq->log = NULL;
424 vq->indirect = NULL;
425 vq->heads = NULL;
426 vq->dev = dev;
427 mutex_init(&vq->mutex);
428 vhost_vq_reset(dev, vq);
429 if (vq->handle_kick)
430 vhost_poll_init(&vq->poll, vq->handle_kick,
431 POLLIN, dev);
432 }
433 }
434 EXPORT_SYMBOL_GPL(vhost_dev_init);
435
436 /* Caller should have device mutex */
437 long vhost_dev_check_owner(struct vhost_dev *dev)
438 {
439 /* Are you the owner? If not, I don't think you mean to do that */
440 return dev->mm == current->mm ? 0 : -EPERM;
441 }
442 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
443
444 struct vhost_attach_cgroups_struct {
445 struct vhost_work work;
446 struct task_struct *owner;
447 int ret;
448 };
449
450 static void vhost_attach_cgroups_work(struct vhost_work *work)
451 {
452 struct vhost_attach_cgroups_struct *s;
453
454 s = container_of(work, struct vhost_attach_cgroups_struct, work);
455 s->ret = cgroup_attach_task_all(s->owner, current);
456 }
457
458 static int vhost_attach_cgroups(struct vhost_dev *dev)
459 {
460 struct vhost_attach_cgroups_struct attach;
461
462 attach.owner = current;
463 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
464 vhost_work_queue(dev, &attach.work);
465 vhost_work_flush(dev, &attach.work);
466 return attach.ret;
467 }
468
469 /* Caller should have device mutex */
470 bool vhost_dev_has_owner(struct vhost_dev *dev)
471 {
472 return dev->mm;
473 }
474 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
475
476 /* Caller should have device mutex */
477 long vhost_dev_set_owner(struct vhost_dev *dev)
478 {
479 struct task_struct *worker;
480 int err;
481
482 /* Is there an owner already? */
483 if (vhost_dev_has_owner(dev)) {
484 err = -EBUSY;
485 goto err_mm;
486 }
487
488 /* No owner, become one */
489 dev->mm = get_task_mm(current);
490 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
491 if (IS_ERR(worker)) {
492 err = PTR_ERR(worker);
493 goto err_worker;
494 }
495
496 dev->worker = worker;
497 wake_up_process(worker); /* avoid contributing to loadavg */
498
499 err = vhost_attach_cgroups(dev);
500 if (err)
501 goto err_cgroup;
502
503 err = vhost_dev_alloc_iovecs(dev);
504 if (err)
505 goto err_cgroup;
506
507 return 0;
508 err_cgroup:
509 kthread_stop(worker);
510 dev->worker = NULL;
511 err_worker:
512 if (dev->mm)
513 mmput(dev->mm);
514 dev->mm = NULL;
515 err_mm:
516 return err;
517 }
518 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
519
520 static void *vhost_kvzalloc(unsigned long size)
521 {
522 void *n = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
523
524 if (!n)
525 n = vzalloc(size);
526 return n;
527 }
528
529 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
530 {
531 return vhost_kvzalloc(sizeof(struct vhost_umem));
532 }
533 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
534
535 /* Caller should have device mutex */
536 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
537 {
538 int i;
539
540 vhost_dev_cleanup(dev, true);
541
542 /* Restore memory to default empty mapping. */
543 INIT_LIST_HEAD(&umem->umem_list);
544 dev->umem = umem;
545 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
546 * VQs aren't running.
547 */
548 for (i = 0; i < dev->nvqs; ++i)
549 dev->vqs[i]->umem = umem;
550 }
551 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
552
553 void vhost_dev_stop(struct vhost_dev *dev)
554 {
555 int i;
556
557 for (i = 0; i < dev->nvqs; ++i) {
558 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
559 vhost_poll_stop(&dev->vqs[i]->poll);
560 vhost_poll_flush(&dev->vqs[i]->poll);
561 }
562 }
563 }
564 EXPORT_SYMBOL_GPL(vhost_dev_stop);
565
566 static void vhost_umem_free(struct vhost_umem *umem,
567 struct vhost_umem_node *node)
568 {
569 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
570 list_del(&node->link);
571 kfree(node);
572 umem->numem--;
573 }
574
575 static void vhost_umem_clean(struct vhost_umem *umem)
576 {
577 struct vhost_umem_node *node, *tmp;
578
579 if (!umem)
580 return;
581
582 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
583 vhost_umem_free(umem, node);
584
585 kvfree(umem);
586 }
587
588 static void vhost_clear_msg(struct vhost_dev *dev)
589 {
590 struct vhost_msg_node *node, *n;
591
592 spin_lock(&dev->iotlb_lock);
593
594 list_for_each_entry_safe(node, n, &dev->read_list, node) {
595 list_del(&node->node);
596 kfree(node);
597 }
598
599 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
600 list_del(&node->node);
601 kfree(node);
602 }
603
604 spin_unlock(&dev->iotlb_lock);
605 }
606
607 /* Caller should have device mutex if and only if locked is set */
608 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
609 {
610 int i;
611
612 for (i = 0; i < dev->nvqs; ++i) {
613 if (dev->vqs[i]->error_ctx)
614 eventfd_ctx_put(dev->vqs[i]->error_ctx);
615 if (dev->vqs[i]->error)
616 fput(dev->vqs[i]->error);
617 if (dev->vqs[i]->kick)
618 fput(dev->vqs[i]->kick);
619 if (dev->vqs[i]->call_ctx)
620 eventfd_ctx_put(dev->vqs[i]->call_ctx);
621 if (dev->vqs[i]->call)
622 fput(dev->vqs[i]->call);
623 vhost_vq_reset(dev, dev->vqs[i]);
624 }
625 vhost_dev_free_iovecs(dev);
626 if (dev->log_ctx)
627 eventfd_ctx_put(dev->log_ctx);
628 dev->log_ctx = NULL;
629 if (dev->log_file)
630 fput(dev->log_file);
631 dev->log_file = NULL;
632 /* No one will access memory at this point */
633 vhost_umem_clean(dev->umem);
634 dev->umem = NULL;
635 vhost_umem_clean(dev->iotlb);
636 dev->iotlb = NULL;
637 vhost_clear_msg(dev);
638 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
639 WARN_ON(!llist_empty(&dev->work_list));
640 if (dev->worker) {
641 kthread_stop(dev->worker);
642 dev->worker = NULL;
643 }
644 if (dev->mm)
645 mmput(dev->mm);
646 dev->mm = NULL;
647 }
648 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
649
650 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
651 {
652 u64 a = addr / VHOST_PAGE_SIZE / 8;
653
654 /* Make sure 64 bit math will not overflow. */
655 if (a > ULONG_MAX - (unsigned long)log_base ||
656 a + (unsigned long)log_base > ULONG_MAX)
657 return 0;
658
659 return access_ok(VERIFY_WRITE, log_base + a,
660 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
661 }
662
663 static bool vhost_overflow(u64 uaddr, u64 size)
664 {
665 /* Make sure 64 bit math will not overflow. */
666 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
667 }
668
669 /* Caller should have vq mutex and device mutex. */
670 static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
671 int log_all)
672 {
673 struct vhost_umem_node *node;
674
675 if (!umem)
676 return 0;
677
678 list_for_each_entry(node, &umem->umem_list, link) {
679 unsigned long a = node->userspace_addr;
680
681 if (vhost_overflow(node->userspace_addr, node->size))
682 return 0;
683
684
685 if (!access_ok(VERIFY_WRITE, (void __user *)a,
686 node->size))
687 return 0;
688 else if (log_all && !log_access_ok(log_base,
689 node->start,
690 node->size))
691 return 0;
692 }
693 return 1;
694 }
695
696 /* Can we switch to this memory table? */
697 /* Caller should have device mutex but not vq mutex */
698 static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
699 int log_all)
700 {
701 int i;
702
703 for (i = 0; i < d->nvqs; ++i) {
704 int ok;
705 bool log;
706
707 mutex_lock(&d->vqs[i]->mutex);
708 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
709 /* If ring is inactive, will check when it's enabled. */
710 if (d->vqs[i]->private_data)
711 ok = vq_memory_access_ok(d->vqs[i]->log_base,
712 umem, log);
713 else
714 ok = 1;
715 mutex_unlock(&d->vqs[i]->mutex);
716 if (!ok)
717 return 0;
718 }
719 return 1;
720 }
721
722 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
723 struct iovec iov[], int iov_size, int access);
724
725 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
726 const void *from, unsigned size)
727 {
728 int ret;
729
730 if (!vq->iotlb)
731 return __copy_to_user(to, from, size);
732 else {
733 /* This function should be called after iotlb
734 * prefetch, which means we're sure that all vq
735 * could be access through iotlb. So -EAGAIN should
736 * not happen in this case.
737 */
738 /* TODO: more fast path */
739 struct iov_iter t;
740 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
741 ARRAY_SIZE(vq->iotlb_iov),
742 VHOST_ACCESS_WO);
743 if (ret < 0)
744 goto out;
745 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
746 ret = copy_to_iter(from, size, &t);
747 if (ret == size)
748 ret = 0;
749 }
750 out:
751 return ret;
752 }
753
754 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
755 void __user *from, unsigned size)
756 {
757 int ret;
758
759 if (!vq->iotlb)
760 return __copy_from_user(to, from, size);
761 else {
762 /* This function should be called after iotlb
763 * prefetch, which means we're sure that vq
764 * could be access through iotlb. So -EAGAIN should
765 * not happen in this case.
766 */
767 /* TODO: more fast path */
768 struct iov_iter f;
769 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
770 ARRAY_SIZE(vq->iotlb_iov),
771 VHOST_ACCESS_RO);
772 if (ret < 0) {
773 vq_err(vq, "IOTLB translation failure: uaddr "
774 "%p size 0x%llx\n", from,
775 (unsigned long long) size);
776 goto out;
777 }
778 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
779 ret = copy_from_iter(to, size, &f);
780 if (ret == size)
781 ret = 0;
782 }
783
784 out:
785 return ret;
786 }
787
788 static void __user *__vhost_get_user(struct vhost_virtqueue *vq,
789 void __user *addr, unsigned size)
790 {
791 int ret;
792
793 /* This function should be called after iotlb
794 * prefetch, which means we're sure that vq
795 * could be access through iotlb. So -EAGAIN should
796 * not happen in this case.
797 */
798 /* TODO: more fast path */
799 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
800 ARRAY_SIZE(vq->iotlb_iov),
801 VHOST_ACCESS_RO);
802 if (ret < 0) {
803 vq_err(vq, "IOTLB translation failure: uaddr "
804 "%p size 0x%llx\n", addr,
805 (unsigned long long) size);
806 return NULL;
807 }
808
809 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
810 vq_err(vq, "Non atomic userspace memory access: uaddr "
811 "%p size 0x%llx\n", addr,
812 (unsigned long long) size);
813 return NULL;
814 }
815
816 return vq->iotlb_iov[0].iov_base;
817 }
818
819 #define vhost_put_user(vq, x, ptr) \
820 ({ \
821 int ret = -EFAULT; \
822 if (!vq->iotlb) { \
823 ret = __put_user(x, ptr); \
824 } else { \
825 __typeof__(ptr) to = \
826 (__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
827 if (to != NULL) \
828 ret = __put_user(x, to); \
829 else \
830 ret = -EFAULT; \
831 } \
832 ret; \
833 })
834
835 #define vhost_get_user(vq, x, ptr) \
836 ({ \
837 int ret; \
838 if (!vq->iotlb) { \
839 ret = __get_user(x, ptr); \
840 } else { \
841 __typeof__(ptr) from = \
842 (__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
843 if (from != NULL) \
844 ret = __get_user(x, from); \
845 else \
846 ret = -EFAULT; \
847 } \
848 ret; \
849 })
850
851 static void vhost_dev_lock_vqs(struct vhost_dev *d)
852 {
853 int i = 0;
854 for (i = 0; i < d->nvqs; ++i)
855 mutex_lock(&d->vqs[i]->mutex);
856 }
857
858 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
859 {
860 int i = 0;
861 for (i = 0; i < d->nvqs; ++i)
862 mutex_unlock(&d->vqs[i]->mutex);
863 }
864
865 static int vhost_new_umem_range(struct vhost_umem *umem,
866 u64 start, u64 size, u64 end,
867 u64 userspace_addr, int perm)
868 {
869 struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
870
871 if (!node)
872 return -ENOMEM;
873
874 if (umem->numem == max_iotlb_entries) {
875 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
876 vhost_umem_free(umem, tmp);
877 }
878
879 node->start = start;
880 node->size = size;
881 node->last = end;
882 node->userspace_addr = userspace_addr;
883 node->perm = perm;
884 INIT_LIST_HEAD(&node->link);
885 list_add_tail(&node->link, &umem->umem_list);
886 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
887 umem->numem++;
888
889 return 0;
890 }
891
892 static void vhost_del_umem_range(struct vhost_umem *umem,
893 u64 start, u64 end)
894 {
895 struct vhost_umem_node *node;
896
897 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
898 start, end)))
899 vhost_umem_free(umem, node);
900 }
901
902 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
903 struct vhost_iotlb_msg *msg)
904 {
905 struct vhost_msg_node *node, *n;
906
907 spin_lock(&d->iotlb_lock);
908
909 list_for_each_entry_safe(node, n, &d->pending_list, node) {
910 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
911 if (msg->iova <= vq_msg->iova &&
912 msg->iova + msg->size - 1 > vq_msg->iova &&
913 vq_msg->type == VHOST_IOTLB_MISS) {
914 vhost_poll_queue(&node->vq->poll);
915 list_del(&node->node);
916 kfree(node);
917 }
918 }
919
920 spin_unlock(&d->iotlb_lock);
921 }
922
923 static int umem_access_ok(u64 uaddr, u64 size, int access)
924 {
925 unsigned long a = uaddr;
926
927 /* Make sure 64 bit math will not overflow. */
928 if (vhost_overflow(uaddr, size))
929 return -EFAULT;
930
931 if ((access & VHOST_ACCESS_RO) &&
932 !access_ok(VERIFY_READ, (void __user *)a, size))
933 return -EFAULT;
934 if ((access & VHOST_ACCESS_WO) &&
935 !access_ok(VERIFY_WRITE, (void __user *)a, size))
936 return -EFAULT;
937 return 0;
938 }
939
940 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
941 struct vhost_iotlb_msg *msg)
942 {
943 int ret = 0;
944
945 vhost_dev_lock_vqs(dev);
946 switch (msg->type) {
947 case VHOST_IOTLB_UPDATE:
948 if (!dev->iotlb) {
949 ret = -EFAULT;
950 break;
951 }
952 if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
953 ret = -EFAULT;
954 break;
955 }
956 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
957 msg->iova + msg->size - 1,
958 msg->uaddr, msg->perm)) {
959 ret = -ENOMEM;
960 break;
961 }
962 vhost_iotlb_notify_vq(dev, msg);
963 break;
964 case VHOST_IOTLB_INVALIDATE:
965 vhost_del_umem_range(dev->iotlb, msg->iova,
966 msg->iova + msg->size - 1);
967 break;
968 default:
969 ret = -EINVAL;
970 break;
971 }
972
973 vhost_dev_unlock_vqs(dev);
974 return ret;
975 }
976 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
977 struct iov_iter *from)
978 {
979 struct vhost_msg_node node;
980 unsigned size = sizeof(struct vhost_msg);
981 size_t ret;
982 int err;
983
984 if (iov_iter_count(from) < size)
985 return 0;
986 ret = copy_from_iter(&node.msg, size, from);
987 if (ret != size)
988 goto done;
989
990 switch (node.msg.type) {
991 case VHOST_IOTLB_MSG:
992 err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
993 if (err)
994 ret = err;
995 break;
996 default:
997 ret = -EINVAL;
998 break;
999 }
1000
1001 done:
1002 return ret;
1003 }
1004 EXPORT_SYMBOL(vhost_chr_write_iter);
1005
1006 unsigned int vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1007 poll_table *wait)
1008 {
1009 unsigned int mask = 0;
1010
1011 poll_wait(file, &dev->wait, wait);
1012
1013 if (!list_empty(&dev->read_list))
1014 mask |= POLLIN | POLLRDNORM;
1015
1016 return mask;
1017 }
1018 EXPORT_SYMBOL(vhost_chr_poll);
1019
1020 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1021 int noblock)
1022 {
1023 DEFINE_WAIT(wait);
1024 struct vhost_msg_node *node;
1025 ssize_t ret = 0;
1026 unsigned size = sizeof(struct vhost_msg);
1027
1028 if (iov_iter_count(to) < size)
1029 return 0;
1030
1031 while (1) {
1032 if (!noblock)
1033 prepare_to_wait(&dev->wait, &wait,
1034 TASK_INTERRUPTIBLE);
1035
1036 node = vhost_dequeue_msg(dev, &dev->read_list);
1037 if (node)
1038 break;
1039 if (noblock) {
1040 ret = -EAGAIN;
1041 break;
1042 }
1043 if (signal_pending(current)) {
1044 ret = -ERESTARTSYS;
1045 break;
1046 }
1047 if (!dev->iotlb) {
1048 ret = -EBADFD;
1049 break;
1050 }
1051
1052 schedule();
1053 }
1054
1055 if (!noblock)
1056 finish_wait(&dev->wait, &wait);
1057
1058 if (node) {
1059 ret = copy_to_iter(&node->msg, size, to);
1060
1061 if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {
1062 kfree(node);
1063 return ret;
1064 }
1065
1066 vhost_enqueue_msg(dev, &dev->pending_list, node);
1067 }
1068
1069 return ret;
1070 }
1071 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1072
1073 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1074 {
1075 struct vhost_dev *dev = vq->dev;
1076 struct vhost_msg_node *node;
1077 struct vhost_iotlb_msg *msg;
1078
1079 node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
1080 if (!node)
1081 return -ENOMEM;
1082
1083 msg = &node->msg.iotlb;
1084 msg->type = VHOST_IOTLB_MISS;
1085 msg->iova = iova;
1086 msg->perm = access;
1087
1088 vhost_enqueue_msg(dev, &dev->read_list, node);
1089
1090 return 0;
1091 }
1092
1093 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1094 struct vring_desc __user *desc,
1095 struct vring_avail __user *avail,
1096 struct vring_used __user *used)
1097
1098 {
1099 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1100
1101 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
1102 access_ok(VERIFY_READ, avail,
1103 sizeof *avail + num * sizeof *avail->ring + s) &&
1104 access_ok(VERIFY_WRITE, used,
1105 sizeof *used + num * sizeof *used->ring + s);
1106 }
1107
1108 static int iotlb_access_ok(struct vhost_virtqueue *vq,
1109 int access, u64 addr, u64 len)
1110 {
1111 const struct vhost_umem_node *node;
1112 struct vhost_umem *umem = vq->iotlb;
1113 u64 s = 0, size;
1114
1115 while (len > s) {
1116 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1117 addr,
1118 addr + len - 1);
1119 if (node == NULL || node->start > addr) {
1120 vhost_iotlb_miss(vq, addr, access);
1121 return false;
1122 } else if (!(node->perm & access)) {
1123 /* Report the possible access violation by
1124 * request another translation from userspace.
1125 */
1126 return false;
1127 }
1128
1129 size = node->size - addr + node->start;
1130 s += size;
1131 addr += size;
1132 }
1133
1134 return true;
1135 }
1136
1137 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1138 {
1139 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1140 unsigned int num = vq->num;
1141
1142 if (!vq->iotlb)
1143 return 1;
1144
1145 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1146 num * sizeof *vq->desc) &&
1147 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1148 sizeof *vq->avail +
1149 num * sizeof *vq->avail->ring + s) &&
1150 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1151 sizeof *vq->used +
1152 num * sizeof *vq->used->ring + s);
1153 }
1154 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1155
1156 /* Can we log writes? */
1157 /* Caller should have device mutex but not vq mutex */
1158 int vhost_log_access_ok(struct vhost_dev *dev)
1159 {
1160 return memory_access_ok(dev, dev->umem, 1);
1161 }
1162 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1163
1164 /* Verify access for write logging. */
1165 /* Caller should have vq mutex and device mutex */
1166 static int vq_log_access_ok(struct vhost_virtqueue *vq,
1167 void __user *log_base)
1168 {
1169 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1170
1171 return vq_memory_access_ok(log_base, vq->umem,
1172 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1173 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1174 sizeof *vq->used +
1175 vq->num * sizeof *vq->used->ring + s));
1176 }
1177
1178 /* Can we start vq? */
1179 /* Caller should have vq mutex and device mutex */
1180 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
1181 {
1182 if (vq->iotlb) {
1183 /* When device IOTLB was used, the access validation
1184 * will be validated during prefetching.
1185 */
1186 return 1;
1187 }
1188 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
1189 vq_log_access_ok(vq, vq->log_base);
1190 }
1191 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1192
1193 static struct vhost_umem *vhost_umem_alloc(void)
1194 {
1195 struct vhost_umem *umem = vhost_kvzalloc(sizeof(*umem));
1196
1197 if (!umem)
1198 return NULL;
1199
1200 umem->umem_tree = RB_ROOT;
1201 umem->numem = 0;
1202 INIT_LIST_HEAD(&umem->umem_list);
1203
1204 return umem;
1205 }
1206
1207 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1208 {
1209 struct vhost_memory mem, *newmem;
1210 struct vhost_memory_region *region;
1211 struct vhost_umem *newumem, *oldumem;
1212 unsigned long size = offsetof(struct vhost_memory, regions);
1213 int i;
1214
1215 if (copy_from_user(&mem, m, size))
1216 return -EFAULT;
1217 if (mem.padding)
1218 return -EOPNOTSUPP;
1219 if (mem.nregions > max_mem_regions)
1220 return -E2BIG;
1221 newmem = vhost_kvzalloc(size + mem.nregions * sizeof(*m->regions));
1222 if (!newmem)
1223 return -ENOMEM;
1224
1225 memcpy(newmem, &mem, size);
1226 if (copy_from_user(newmem->regions, m->regions,
1227 mem.nregions * sizeof *m->regions)) {
1228 kvfree(newmem);
1229 return -EFAULT;
1230 }
1231
1232 newumem = vhost_umem_alloc();
1233 if (!newumem) {
1234 kvfree(newmem);
1235 return -ENOMEM;
1236 }
1237
1238 for (region = newmem->regions;
1239 region < newmem->regions + mem.nregions;
1240 region++) {
1241 if (vhost_new_umem_range(newumem,
1242 region->guest_phys_addr,
1243 region->memory_size,
1244 region->guest_phys_addr +
1245 region->memory_size - 1,
1246 region->userspace_addr,
1247 VHOST_ACCESS_RW))
1248 goto err;
1249 }
1250
1251 if (!memory_access_ok(d, newumem, 0))
1252 goto err;
1253
1254 oldumem = d->umem;
1255 d->umem = newumem;
1256
1257 /* All memory accesses are done under some VQ mutex. */
1258 for (i = 0; i < d->nvqs; ++i) {
1259 mutex_lock(&d->vqs[i]->mutex);
1260 d->vqs[i]->umem = newumem;
1261 mutex_unlock(&d->vqs[i]->mutex);
1262 }
1263
1264 kvfree(newmem);
1265 vhost_umem_clean(oldumem);
1266 return 0;
1267
1268 err:
1269 vhost_umem_clean(newumem);
1270 kvfree(newmem);
1271 return -EFAULT;
1272 }
1273
1274 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
1275 {
1276 struct file *eventfp, *filep = NULL;
1277 bool pollstart = false, pollstop = false;
1278 struct eventfd_ctx *ctx = NULL;
1279 u32 __user *idxp = argp;
1280 struct vhost_virtqueue *vq;
1281 struct vhost_vring_state s;
1282 struct vhost_vring_file f;
1283 struct vhost_vring_addr a;
1284 u32 idx;
1285 long r;
1286
1287 r = get_user(idx, idxp);
1288 if (r < 0)
1289 return r;
1290 if (idx >= d->nvqs)
1291 return -ENOBUFS;
1292
1293 vq = d->vqs[idx];
1294
1295 mutex_lock(&vq->mutex);
1296
1297 switch (ioctl) {
1298 case VHOST_SET_VRING_NUM:
1299 /* Resizing ring with an active backend?
1300 * You don't want to do that. */
1301 if (vq->private_data) {
1302 r = -EBUSY;
1303 break;
1304 }
1305 if (copy_from_user(&s, argp, sizeof s)) {
1306 r = -EFAULT;
1307 break;
1308 }
1309 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1310 r = -EINVAL;
1311 break;
1312 }
1313 vq->num = s.num;
1314 break;
1315 case VHOST_SET_VRING_BASE:
1316 /* Moving base with an active backend?
1317 * You don't want to do that. */
1318 if (vq->private_data) {
1319 r = -EBUSY;
1320 break;
1321 }
1322 if (copy_from_user(&s, argp, sizeof s)) {
1323 r = -EFAULT;
1324 break;
1325 }
1326 if (s.num > 0xffff) {
1327 r = -EINVAL;
1328 break;
1329 }
1330 vq->last_avail_idx = vq->last_used_event = s.num;
1331 /* Forget the cached index value. */
1332 vq->avail_idx = vq->last_avail_idx;
1333 break;
1334 case VHOST_GET_VRING_BASE:
1335 s.index = idx;
1336 s.num = vq->last_avail_idx;
1337 if (copy_to_user(argp, &s, sizeof s))
1338 r = -EFAULT;
1339 break;
1340 case VHOST_SET_VRING_ADDR:
1341 if (copy_from_user(&a, argp, sizeof a)) {
1342 r = -EFAULT;
1343 break;
1344 }
1345 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1346 r = -EOPNOTSUPP;
1347 break;
1348 }
1349 /* For 32bit, verify that the top 32bits of the user
1350 data are set to zero. */
1351 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1352 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1353 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1354 r = -EFAULT;
1355 break;
1356 }
1357
1358 /* Make sure it's safe to cast pointers to vring types. */
1359 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1360 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1361 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1362 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1363 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1364 r = -EINVAL;
1365 break;
1366 }
1367
1368 /* We only verify access here if backend is configured.
1369 * If it is not, we don't as size might not have been setup.
1370 * We will verify when backend is configured. */
1371 if (vq->private_data) {
1372 if (!vq_access_ok(vq, vq->num,
1373 (void __user *)(unsigned long)a.desc_user_addr,
1374 (void __user *)(unsigned long)a.avail_user_addr,
1375 (void __user *)(unsigned long)a.used_user_addr)) {
1376 r = -EINVAL;
1377 break;
1378 }
1379
1380 /* Also validate log access for used ring if enabled. */
1381 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1382 !log_access_ok(vq->log_base, a.log_guest_addr,
1383 sizeof *vq->used +
1384 vq->num * sizeof *vq->used->ring)) {
1385 r = -EINVAL;
1386 break;
1387 }
1388 }
1389
1390 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1391 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1392 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1393 vq->log_addr = a.log_guest_addr;
1394 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1395 break;
1396 case VHOST_SET_VRING_KICK:
1397 if (copy_from_user(&f, argp, sizeof f)) {
1398 r = -EFAULT;
1399 break;
1400 }
1401 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1402 if (IS_ERR(eventfp)) {
1403 r = PTR_ERR(eventfp);
1404 break;
1405 }
1406 if (eventfp != vq->kick) {
1407 pollstop = (filep = vq->kick) != NULL;
1408 pollstart = (vq->kick = eventfp) != NULL;
1409 } else
1410 filep = eventfp;
1411 break;
1412 case VHOST_SET_VRING_CALL:
1413 if (copy_from_user(&f, argp, sizeof f)) {
1414 r = -EFAULT;
1415 break;
1416 }
1417 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1418 if (IS_ERR(eventfp)) {
1419 r = PTR_ERR(eventfp);
1420 break;
1421 }
1422 if (eventfp != vq->call) {
1423 filep = vq->call;
1424 ctx = vq->call_ctx;
1425 vq->call = eventfp;
1426 vq->call_ctx = eventfp ?
1427 eventfd_ctx_fileget(eventfp) : NULL;
1428 } else
1429 filep = eventfp;
1430 break;
1431 case VHOST_SET_VRING_ERR:
1432 if (copy_from_user(&f, argp, sizeof f)) {
1433 r = -EFAULT;
1434 break;
1435 }
1436 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1437 if (IS_ERR(eventfp)) {
1438 r = PTR_ERR(eventfp);
1439 break;
1440 }
1441 if (eventfp != vq->error) {
1442 filep = vq->error;
1443 vq->error = eventfp;
1444 ctx = vq->error_ctx;
1445 vq->error_ctx = eventfp ?
1446 eventfd_ctx_fileget(eventfp) : NULL;
1447 } else
1448 filep = eventfp;
1449 break;
1450 case VHOST_SET_VRING_ENDIAN:
1451 r = vhost_set_vring_endian(vq, argp);
1452 break;
1453 case VHOST_GET_VRING_ENDIAN:
1454 r = vhost_get_vring_endian(vq, idx, argp);
1455 break;
1456 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1457 if (copy_from_user(&s, argp, sizeof(s))) {
1458 r = -EFAULT;
1459 break;
1460 }
1461 vq->busyloop_timeout = s.num;
1462 break;
1463 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1464 s.index = idx;
1465 s.num = vq->busyloop_timeout;
1466 if (copy_to_user(argp, &s, sizeof(s)))
1467 r = -EFAULT;
1468 break;
1469 default:
1470 r = -ENOIOCTLCMD;
1471 }
1472
1473 if (pollstop && vq->handle_kick)
1474 vhost_poll_stop(&vq->poll);
1475
1476 if (ctx)
1477 eventfd_ctx_put(ctx);
1478 if (filep)
1479 fput(filep);
1480
1481 if (pollstart && vq->handle_kick)
1482 r = vhost_poll_start(&vq->poll, vq->kick);
1483
1484 mutex_unlock(&vq->mutex);
1485
1486 if (pollstop && vq->handle_kick)
1487 vhost_poll_flush(&vq->poll);
1488 return r;
1489 }
1490 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1491
1492 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1493 {
1494 struct vhost_umem *niotlb, *oiotlb;
1495 int i;
1496
1497 niotlb = vhost_umem_alloc();
1498 if (!niotlb)
1499 return -ENOMEM;
1500
1501 oiotlb = d->iotlb;
1502 d->iotlb = niotlb;
1503
1504 for (i = 0; i < d->nvqs; ++i) {
1505 mutex_lock(&d->vqs[i]->mutex);
1506 d->vqs[i]->iotlb = niotlb;
1507 mutex_unlock(&d->vqs[i]->mutex);
1508 }
1509
1510 vhost_umem_clean(oiotlb);
1511
1512 return 0;
1513 }
1514 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1515
1516 /* Caller must have device mutex */
1517 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1518 {
1519 struct file *eventfp, *filep = NULL;
1520 struct eventfd_ctx *ctx = NULL;
1521 u64 p;
1522 long r;
1523 int i, fd;
1524
1525 /* If you are not the owner, you can become one */
1526 if (ioctl == VHOST_SET_OWNER) {
1527 r = vhost_dev_set_owner(d);
1528 goto done;
1529 }
1530
1531 /* You must be the owner to do anything else */
1532 r = vhost_dev_check_owner(d);
1533 if (r)
1534 goto done;
1535
1536 switch (ioctl) {
1537 case VHOST_SET_MEM_TABLE:
1538 r = vhost_set_memory(d, argp);
1539 break;
1540 case VHOST_SET_LOG_BASE:
1541 if (copy_from_user(&p, argp, sizeof p)) {
1542 r = -EFAULT;
1543 break;
1544 }
1545 if ((u64)(unsigned long)p != p) {
1546 r = -EFAULT;
1547 break;
1548 }
1549 for (i = 0; i < d->nvqs; ++i) {
1550 struct vhost_virtqueue *vq;
1551 void __user *base = (void __user *)(unsigned long)p;
1552 vq = d->vqs[i];
1553 mutex_lock(&vq->mutex);
1554 /* If ring is inactive, will check when it's enabled. */
1555 if (vq->private_data && !vq_log_access_ok(vq, base))
1556 r = -EFAULT;
1557 else
1558 vq->log_base = base;
1559 mutex_unlock(&vq->mutex);
1560 }
1561 break;
1562 case VHOST_SET_LOG_FD:
1563 r = get_user(fd, (int __user *)argp);
1564 if (r < 0)
1565 break;
1566 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
1567 if (IS_ERR(eventfp)) {
1568 r = PTR_ERR(eventfp);
1569 break;
1570 }
1571 if (eventfp != d->log_file) {
1572 filep = d->log_file;
1573 d->log_file = eventfp;
1574 ctx = d->log_ctx;
1575 d->log_ctx = eventfp ?
1576 eventfd_ctx_fileget(eventfp) : NULL;
1577 } else
1578 filep = eventfp;
1579 for (i = 0; i < d->nvqs; ++i) {
1580 mutex_lock(&d->vqs[i]->mutex);
1581 d->vqs[i]->log_ctx = d->log_ctx;
1582 mutex_unlock(&d->vqs[i]->mutex);
1583 }
1584 if (ctx)
1585 eventfd_ctx_put(ctx);
1586 if (filep)
1587 fput(filep);
1588 break;
1589 default:
1590 r = -ENOIOCTLCMD;
1591 break;
1592 }
1593 done:
1594 return r;
1595 }
1596 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1597
1598 /* TODO: This is really inefficient. We need something like get_user()
1599 * (instruction directly accesses the data, with an exception table entry
1600 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1601 */
1602 static int set_bit_to_user(int nr, void __user *addr)
1603 {
1604 unsigned long log = (unsigned long)addr;
1605 struct page *page;
1606 void *base;
1607 int bit = nr + (log % PAGE_SIZE) * 8;
1608 int r;
1609
1610 r = get_user_pages_fast(log, 1, 1, &page);
1611 if (r < 0)
1612 return r;
1613 BUG_ON(r != 1);
1614 base = kmap_atomic(page);
1615 set_bit(bit, base);
1616 kunmap_atomic(base);
1617 set_page_dirty_lock(page);
1618 put_page(page);
1619 return 0;
1620 }
1621
1622 static int log_write(void __user *log_base,
1623 u64 write_address, u64 write_length)
1624 {
1625 u64 write_page = write_address / VHOST_PAGE_SIZE;
1626 int r;
1627
1628 if (!write_length)
1629 return 0;
1630 write_length += write_address % VHOST_PAGE_SIZE;
1631 for (;;) {
1632 u64 base = (u64)(unsigned long)log_base;
1633 u64 log = base + write_page / 8;
1634 int bit = write_page % 8;
1635 if ((u64)(unsigned long)log != log)
1636 return -EFAULT;
1637 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1638 if (r < 0)
1639 return r;
1640 if (write_length <= VHOST_PAGE_SIZE)
1641 break;
1642 write_length -= VHOST_PAGE_SIZE;
1643 write_page += 1;
1644 }
1645 return r;
1646 }
1647
1648 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1649 unsigned int log_num, u64 len)
1650 {
1651 int i, r;
1652
1653 /* Make sure data written is seen before log. */
1654 smp_wmb();
1655 for (i = 0; i < log_num; ++i) {
1656 u64 l = min(log[i].len, len);
1657 r = log_write(vq->log_base, log[i].addr, l);
1658 if (r < 0)
1659 return r;
1660 len -= l;
1661 if (!len) {
1662 if (vq->log_ctx)
1663 eventfd_signal(vq->log_ctx, 1);
1664 return 0;
1665 }
1666 }
1667 /* Length written exceeds what we have stored. This is a bug. */
1668 BUG();
1669 return 0;
1670 }
1671 EXPORT_SYMBOL_GPL(vhost_log_write);
1672
1673 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1674 {
1675 void __user *used;
1676 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1677 &vq->used->flags) < 0)
1678 return -EFAULT;
1679 if (unlikely(vq->log_used)) {
1680 /* Make sure the flag is seen before log. */
1681 smp_wmb();
1682 /* Log used flag write. */
1683 used = &vq->used->flags;
1684 log_write(vq->log_base, vq->log_addr +
1685 (used - (void __user *)vq->used),
1686 sizeof vq->used->flags);
1687 if (vq->log_ctx)
1688 eventfd_signal(vq->log_ctx, 1);
1689 }
1690 return 0;
1691 }
1692
1693 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1694 {
1695 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1696 vhost_avail_event(vq)))
1697 return -EFAULT;
1698 if (unlikely(vq->log_used)) {
1699 void __user *used;
1700 /* Make sure the event is seen before log. */
1701 smp_wmb();
1702 /* Log avail event write */
1703 used = vhost_avail_event(vq);
1704 log_write(vq->log_base, vq->log_addr +
1705 (used - (void __user *)vq->used),
1706 sizeof *vhost_avail_event(vq));
1707 if (vq->log_ctx)
1708 eventfd_signal(vq->log_ctx, 1);
1709 }
1710 return 0;
1711 }
1712
1713 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1714 {
1715 __virtio16 last_used_idx;
1716 int r;
1717 bool is_le = vq->is_le;
1718
1719 if (!vq->private_data)
1720 return 0;
1721
1722 vhost_init_is_le(vq);
1723
1724 r = vhost_update_used_flags(vq);
1725 if (r)
1726 goto err;
1727 vq->signalled_used_valid = false;
1728 if (!vq->iotlb &&
1729 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1730 r = -EFAULT;
1731 goto err;
1732 }
1733 r = vhost_get_user(vq, last_used_idx, &vq->used->idx);
1734 if (r) {
1735 vq_err(vq, "Can't access used idx at %p\n",
1736 &vq->used->idx);
1737 goto err;
1738 }
1739 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1740 return 0;
1741
1742 err:
1743 vq->is_le = is_le;
1744 return r;
1745 }
1746 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1747
1748 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1749 struct iovec iov[], int iov_size, int access)
1750 {
1751 const struct vhost_umem_node *node;
1752 struct vhost_dev *dev = vq->dev;
1753 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1754 struct iovec *_iov;
1755 u64 s = 0;
1756 int ret = 0;
1757
1758 while ((u64)len > s) {
1759 u64 size;
1760 if (unlikely(ret >= iov_size)) {
1761 ret = -ENOBUFS;
1762 break;
1763 }
1764
1765 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1766 addr, addr + len - 1);
1767 if (node == NULL || node->start > addr) {
1768 if (umem != dev->iotlb) {
1769 ret = -EFAULT;
1770 break;
1771 }
1772 ret = -EAGAIN;
1773 break;
1774 } else if (!(node->perm & access)) {
1775 ret = -EPERM;
1776 break;
1777 }
1778
1779 _iov = iov + ret;
1780 size = node->size - addr + node->start;
1781 _iov->iov_len = min((u64)len - s, size);
1782 _iov->iov_base = (void __user *)(unsigned long)
1783 (node->userspace_addr + addr - node->start);
1784 s += size;
1785 addr += size;
1786 ++ret;
1787 }
1788
1789 if (ret == -EAGAIN)
1790 vhost_iotlb_miss(vq, addr, access);
1791 return ret;
1792 }
1793
1794 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1795 * function returns the next descriptor in the chain,
1796 * or -1U if we're at the end. */
1797 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1798 {
1799 unsigned int next;
1800
1801 /* If this descriptor says it doesn't chain, we're done. */
1802 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1803 return -1U;
1804
1805 /* Check they're not leading us off end of descriptors. */
1806 next = vhost16_to_cpu(vq, desc->next);
1807 /* Make sure compiler knows to grab that: we don't want it changing! */
1808 /* We will use the result as an index in an array, so most
1809 * architectures only need a compiler barrier here. */
1810 read_barrier_depends();
1811
1812 return next;
1813 }
1814
1815 static int get_indirect(struct vhost_virtqueue *vq,
1816 struct iovec iov[], unsigned int iov_size,
1817 unsigned int *out_num, unsigned int *in_num,
1818 struct vhost_log *log, unsigned int *log_num,
1819 struct vring_desc *indirect)
1820 {
1821 struct vring_desc desc;
1822 unsigned int i = 0, count, found = 0;
1823 u32 len = vhost32_to_cpu(vq, indirect->len);
1824 struct iov_iter from;
1825 int ret, access;
1826
1827 /* Sanity check */
1828 if (unlikely(len % sizeof desc)) {
1829 vq_err(vq, "Invalid length in indirect descriptor: "
1830 "len 0x%llx not multiple of 0x%zx\n",
1831 (unsigned long long)len,
1832 sizeof desc);
1833 return -EINVAL;
1834 }
1835
1836 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1837 UIO_MAXIOV, VHOST_ACCESS_RO);
1838 if (unlikely(ret < 0)) {
1839 if (ret != -EAGAIN)
1840 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1841 return ret;
1842 }
1843 iov_iter_init(&from, READ, vq->indirect, ret, len);
1844
1845 /* We will use the result as an address to read from, so most
1846 * architectures only need a compiler barrier here. */
1847 read_barrier_depends();
1848
1849 count = len / sizeof desc;
1850 /* Buffers are chained via a 16 bit next field, so
1851 * we can have at most 2^16 of these. */
1852 if (unlikely(count > USHRT_MAX + 1)) {
1853 vq_err(vq, "Indirect buffer length too big: %d\n",
1854 indirect->len);
1855 return -E2BIG;
1856 }
1857
1858 do {
1859 unsigned iov_count = *in_num + *out_num;
1860 if (unlikely(++found > count)) {
1861 vq_err(vq, "Loop detected: last one at %u "
1862 "indirect size %u\n",
1863 i, count);
1864 return -EINVAL;
1865 }
1866 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1867 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1868 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1869 return -EINVAL;
1870 }
1871 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1872 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1873 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1874 return -EINVAL;
1875 }
1876
1877 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1878 access = VHOST_ACCESS_WO;
1879 else
1880 access = VHOST_ACCESS_RO;
1881
1882 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1883 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1884 iov_size - iov_count, access);
1885 if (unlikely(ret < 0)) {
1886 if (ret != -EAGAIN)
1887 vq_err(vq, "Translation failure %d indirect idx %d\n",
1888 ret, i);
1889 return ret;
1890 }
1891 /* If this is an input descriptor, increment that count. */
1892 if (access == VHOST_ACCESS_WO) {
1893 *in_num += ret;
1894 if (unlikely(log)) {
1895 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1896 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1897 ++*log_num;
1898 }
1899 } else {
1900 /* If it's an output descriptor, they're all supposed
1901 * to come before any input descriptors. */
1902 if (unlikely(*in_num)) {
1903 vq_err(vq, "Indirect descriptor "
1904 "has out after in: idx %d\n", i);
1905 return -EINVAL;
1906 }
1907 *out_num += ret;
1908 }
1909 } while ((i = next_desc(vq, &desc)) != -1);
1910 return 0;
1911 }
1912
1913 /* This looks in the virtqueue and for the first available buffer, and converts
1914 * it to an iovec for convenient access. Since descriptors consist of some
1915 * number of output then some number of input descriptors, it's actually two
1916 * iovecs, but we pack them into one and note how many of each there were.
1917 *
1918 * This function returns the descriptor number found, or vq->num (which is
1919 * never a valid descriptor number) if none was found. A negative code is
1920 * returned on error. */
1921 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1922 struct iovec iov[], unsigned int iov_size,
1923 unsigned int *out_num, unsigned int *in_num,
1924 struct vhost_log *log, unsigned int *log_num)
1925 {
1926 struct vring_desc desc;
1927 unsigned int i, head, found = 0;
1928 u16 last_avail_idx;
1929 __virtio16 avail_idx;
1930 __virtio16 ring_head;
1931 int ret, access;
1932
1933 /* Check it isn't doing very strange things with descriptor numbers. */
1934 last_avail_idx = vq->last_avail_idx;
1935 if (unlikely(vhost_get_user(vq, avail_idx, &vq->avail->idx))) {
1936 vq_err(vq, "Failed to access avail idx at %p\n",
1937 &vq->avail->idx);
1938 return -EFAULT;
1939 }
1940 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1941
1942 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1943 vq_err(vq, "Guest moved used index from %u to %u",
1944 last_avail_idx, vq->avail_idx);
1945 return -EFAULT;
1946 }
1947
1948 /* If there's nothing new since last we looked, return invalid. */
1949 if (vq->avail_idx == last_avail_idx)
1950 return vq->num;
1951
1952 /* Only get avail ring entries after they have been exposed by guest. */
1953 smp_rmb();
1954
1955 /* Grab the next descriptor number they're advertising, and increment
1956 * the index we've seen. */
1957 if (unlikely(vhost_get_user(vq, ring_head,
1958 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
1959 vq_err(vq, "Failed to read head: idx %d address %p\n",
1960 last_avail_idx,
1961 &vq->avail->ring[last_avail_idx % vq->num]);
1962 return -EFAULT;
1963 }
1964
1965 head = vhost16_to_cpu(vq, ring_head);
1966
1967 /* If their number is silly, that's an error. */
1968 if (unlikely(head >= vq->num)) {
1969 vq_err(vq, "Guest says index %u > %u is available",
1970 head, vq->num);
1971 return -EINVAL;
1972 }
1973
1974 /* When we start there are none of either input nor output. */
1975 *out_num = *in_num = 0;
1976 if (unlikely(log))
1977 *log_num = 0;
1978
1979 i = head;
1980 do {
1981 unsigned iov_count = *in_num + *out_num;
1982 if (unlikely(i >= vq->num)) {
1983 vq_err(vq, "Desc index is %u > %u, head = %u",
1984 i, vq->num, head);
1985 return -EINVAL;
1986 }
1987 if (unlikely(++found > vq->num)) {
1988 vq_err(vq, "Loop detected: last one at %u "
1989 "vq size %u head %u\n",
1990 i, vq->num, head);
1991 return -EINVAL;
1992 }
1993 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
1994 sizeof desc);
1995 if (unlikely(ret)) {
1996 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1997 i, vq->desc + i);
1998 return -EFAULT;
1999 }
2000 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2001 ret = get_indirect(vq, iov, iov_size,
2002 out_num, in_num,
2003 log, log_num, &desc);
2004 if (unlikely(ret < 0)) {
2005 if (ret != -EAGAIN)
2006 vq_err(vq, "Failure detected "
2007 "in indirect descriptor at idx %d\n", i);
2008 return ret;
2009 }
2010 continue;
2011 }
2012
2013 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2014 access = VHOST_ACCESS_WO;
2015 else
2016 access = VHOST_ACCESS_RO;
2017 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2018 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2019 iov_size - iov_count, access);
2020 if (unlikely(ret < 0)) {
2021 if (ret != -EAGAIN)
2022 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2023 ret, i);
2024 return ret;
2025 }
2026 if (access == VHOST_ACCESS_WO) {
2027 /* If this is an input descriptor,
2028 * increment that count. */
2029 *in_num += ret;
2030 if (unlikely(log)) {
2031 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2032 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2033 ++*log_num;
2034 }
2035 } else {
2036 /* If it's an output descriptor, they're all supposed
2037 * to come before any input descriptors. */
2038 if (unlikely(*in_num)) {
2039 vq_err(vq, "Descriptor has out after in: "
2040 "idx %d\n", i);
2041 return -EINVAL;
2042 }
2043 *out_num += ret;
2044 }
2045 } while ((i = next_desc(vq, &desc)) != -1);
2046
2047 /* On success, increment avail index. */
2048 vq->last_avail_idx++;
2049
2050 /* Assume notifications from guest are disabled at this point,
2051 * if they aren't we would need to update avail_event index. */
2052 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2053 return head;
2054 }
2055 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2056
2057 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2058 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2059 {
2060 vq->last_avail_idx -= n;
2061 }
2062 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2063
2064 /* After we've used one of their buffers, we tell them about it. We'll then
2065 * want to notify the guest, using eventfd. */
2066 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2067 {
2068 struct vring_used_elem heads = {
2069 cpu_to_vhost32(vq, head),
2070 cpu_to_vhost32(vq, len)
2071 };
2072
2073 return vhost_add_used_n(vq, &heads, 1);
2074 }
2075 EXPORT_SYMBOL_GPL(vhost_add_used);
2076
2077 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2078 struct vring_used_elem *heads,
2079 unsigned count)
2080 {
2081 struct vring_used_elem __user *used;
2082 u16 old, new;
2083 int start;
2084
2085 start = vq->last_used_idx & (vq->num - 1);
2086 used = vq->used->ring + start;
2087 if (count == 1) {
2088 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2089 vq_err(vq, "Failed to write used id");
2090 return -EFAULT;
2091 }
2092 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2093 vq_err(vq, "Failed to write used len");
2094 return -EFAULT;
2095 }
2096 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2097 vq_err(vq, "Failed to write used");
2098 return -EFAULT;
2099 }
2100 if (unlikely(vq->log_used)) {
2101 /* Make sure data is seen before log. */
2102 smp_wmb();
2103 /* Log used ring entry write. */
2104 log_write(vq->log_base,
2105 vq->log_addr +
2106 ((void __user *)used - (void __user *)vq->used),
2107 count * sizeof *used);
2108 }
2109 old = vq->last_used_idx;
2110 new = (vq->last_used_idx += count);
2111 /* If the driver never bothers to signal in a very long while,
2112 * used index might wrap around. If that happens, invalidate
2113 * signalled_used index we stored. TODO: make sure driver
2114 * signals at least once in 2^16 and remove this. */
2115 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2116 vq->signalled_used_valid = false;
2117 return 0;
2118 }
2119
2120 /* After we've used one of their buffers, we tell them about it. We'll then
2121 * want to notify the guest, using eventfd. */
2122 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2123 unsigned count)
2124 {
2125 int start, n, r;
2126
2127 start = vq->last_used_idx & (vq->num - 1);
2128 n = vq->num - start;
2129 if (n < count) {
2130 r = __vhost_add_used_n(vq, heads, n);
2131 if (r < 0)
2132 return r;
2133 heads += n;
2134 count -= n;
2135 }
2136 r = __vhost_add_used_n(vq, heads, count);
2137
2138 /* Make sure buffer is written before we update index. */
2139 smp_wmb();
2140 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2141 &vq->used->idx)) {
2142 vq_err(vq, "Failed to increment used idx");
2143 return -EFAULT;
2144 }
2145 if (unlikely(vq->log_used)) {
2146 /* Log used index update. */
2147 log_write(vq->log_base,
2148 vq->log_addr + offsetof(struct vring_used, idx),
2149 sizeof vq->used->idx);
2150 if (vq->log_ctx)
2151 eventfd_signal(vq->log_ctx, 1);
2152 }
2153 return r;
2154 }
2155 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2156
2157 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2158 {
2159 __u16 old, new;
2160 __virtio16 event;
2161 bool v;
2162
2163 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2164 unlikely(vq->avail_idx == vq->last_avail_idx))
2165 return true;
2166
2167 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2168 __virtio16 flags;
2169 /* Flush out used index updates. This is paired
2170 * with the barrier that the Guest executes when enabling
2171 * interrupts. */
2172 smp_mb();
2173 if (vhost_get_user(vq, flags, &vq->avail->flags)) {
2174 vq_err(vq, "Failed to get flags");
2175 return true;
2176 }
2177 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2178 }
2179 old = vq->signalled_used;
2180 v = vq->signalled_used_valid;
2181 new = vq->signalled_used = vq->last_used_idx;
2182 vq->signalled_used_valid = true;
2183
2184 if (unlikely(!v))
2185 return true;
2186
2187 /* We're sure if the following conditions are met, there's no
2188 * need to notify guest:
2189 * 1) cached used event is ahead of new
2190 * 2) old to new updating does not cross cached used event. */
2191 if (vring_need_event(vq->last_used_event, new + vq->num, new) &&
2192 !vring_need_event(vq->last_used_event, new, old))
2193 return false;
2194
2195 /* Flush out used index updates. This is paired
2196 * with the barrier that the Guest executes when enabling
2197 * interrupts. */
2198 smp_mb();
2199
2200 if (vhost_get_user(vq, event, vhost_used_event(vq))) {
2201 vq_err(vq, "Failed to get used event idx");
2202 return true;
2203 }
2204 vq->last_used_event = vhost16_to_cpu(vq, event);
2205
2206 return vring_need_event(vq->last_used_event, new, old);
2207 }
2208
2209 /* This actually signals the guest, using eventfd. */
2210 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2211 {
2212 /* Signal the Guest tell them we used something up. */
2213 if (vq->call_ctx && vhost_notify(dev, vq))
2214 eventfd_signal(vq->call_ctx, 1);
2215 }
2216 EXPORT_SYMBOL_GPL(vhost_signal);
2217
2218 /* And here's the combo meal deal. Supersize me! */
2219 void vhost_add_used_and_signal(struct vhost_dev *dev,
2220 struct vhost_virtqueue *vq,
2221 unsigned int head, int len)
2222 {
2223 vhost_add_used(vq, head, len);
2224 vhost_signal(dev, vq);
2225 }
2226 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2227
2228 /* multi-buffer version of vhost_add_used_and_signal */
2229 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2230 struct vhost_virtqueue *vq,
2231 struct vring_used_elem *heads, unsigned count)
2232 {
2233 vhost_add_used_n(vq, heads, count);
2234 vhost_signal(dev, vq);
2235 }
2236 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2237
2238 /* return true if we're sure that avaiable ring is empty */
2239 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2240 {
2241 __virtio16 avail_idx;
2242 int r;
2243
2244 if (vq->avail_idx != vq->last_avail_idx)
2245 return false;
2246
2247 r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
2248 if (unlikely(r))
2249 return false;
2250 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2251
2252 return vq->avail_idx == vq->last_avail_idx;
2253 }
2254 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2255
2256 /* OK, now we need to know about added descriptors. */
2257 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2258 {
2259 __virtio16 avail_idx;
2260 int r;
2261
2262 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2263 return false;
2264 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2265 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2266 r = vhost_update_used_flags(vq);
2267 if (r) {
2268 vq_err(vq, "Failed to enable notification at %p: %d\n",
2269 &vq->used->flags, r);
2270 return false;
2271 }
2272 } else {
2273 r = vhost_update_avail_event(vq, vq->avail_idx);
2274 if (r) {
2275 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2276 vhost_avail_event(vq), r);
2277 return false;
2278 }
2279 }
2280 /* They could have slipped one in as we were doing that: make
2281 * sure it's written, then check again. */
2282 smp_mb();
2283 r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
2284 if (r) {
2285 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2286 &vq->avail->idx, r);
2287 return false;
2288 }
2289
2290 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2291 }
2292 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2293
2294 /* We don't need to be notified again. */
2295 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2296 {
2297 int r;
2298
2299 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2300 return;
2301 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2302 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2303 r = vhost_update_used_flags(vq);
2304 if (r)
2305 vq_err(vq, "Failed to enable notification at %p: %d\n",
2306 &vq->used->flags, r);
2307 }
2308 }
2309 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2310
2311 /* Create a new message. */
2312 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2313 {
2314 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2315 if (!node)
2316 return NULL;
2317 node->vq = vq;
2318 node->msg.type = type;
2319 return node;
2320 }
2321 EXPORT_SYMBOL_GPL(vhost_new_msg);
2322
2323 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2324 struct vhost_msg_node *node)
2325 {
2326 spin_lock(&dev->iotlb_lock);
2327 list_add_tail(&node->node, head);
2328 spin_unlock(&dev->iotlb_lock);
2329
2330 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
2331 }
2332 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2333
2334 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2335 struct list_head *head)
2336 {
2337 struct vhost_msg_node *node = NULL;
2338
2339 spin_lock(&dev->iotlb_lock);
2340 if (!list_empty(head)) {
2341 node = list_first_entry(head, struct vhost_msg_node,
2342 node);
2343 list_del(&node->node);
2344 }
2345 spin_unlock(&dev->iotlb_lock);
2346
2347 return node;
2348 }
2349 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2350
2351
2352 static int __init vhost_init(void)
2353 {
2354 return 0;
2355 }
2356
2357 static void __exit vhost_exit(void)
2358 {
2359 }
2360
2361 module_init(vhost_init);
2362 module_exit(vhost_exit);
2363
2364 MODULE_VERSION("0.0.1");
2365 MODULE_LICENSE("GPL v2");
2366 MODULE_AUTHOR("Michael S. Tsirkin");
2367 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
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