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doc: Update rcu_assign_pointer() definition in whatisRCU.txt
[linux/fpc-iii.git] / drivers / vhost / vhost.c
blobf0ba362d4c101aa970a12943d1e69944d54058b7
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_meta_reset(struct vhost_virtqueue *vq)
288 {
289 int j;
290
291 for (j = 0; j < VHOST_NUM_ADDRS; j++)
292 vq->meta_iotlb[j] = NULL;
293 }
294
295 static void vhost_vq_meta_reset(struct vhost_dev *d)
296 {
297 int i;
298
299 for (i = 0; i < d->nvqs; ++i)
300 __vhost_vq_meta_reset(d->vqs[i]);
301 }
302
303 static void vhost_vq_reset(struct vhost_dev *dev,
304 struct vhost_virtqueue *vq)
305 {
306 vq->num = 1;
307 vq->desc = NULL;
308 vq->avail = NULL;
309 vq->used = NULL;
310 vq->last_avail_idx = 0;
311 vq->last_used_event = 0;
312 vq->avail_idx = 0;
313 vq->last_used_idx = 0;
314 vq->signalled_used = 0;
315 vq->signalled_used_valid = false;
316 vq->used_flags = 0;
317 vq->log_used = false;
318 vq->log_addr = -1ull;
319 vq->private_data = NULL;
320 vq->acked_features = 0;
321 vq->log_base = NULL;
322 vq->error_ctx = NULL;
323 vq->error = NULL;
324 vq->kick = NULL;
325 vq->call_ctx = NULL;
326 vq->call = NULL;
327 vq->log_ctx = NULL;
328 vhost_reset_is_le(vq);
329 vhost_disable_cross_endian(vq);
330 vq->busyloop_timeout = 0;
331 vq->umem = NULL;
332 vq->iotlb = NULL;
333 __vhost_vq_meta_reset(vq);
334 }
335
336 static int vhost_worker(void *data)
337 {
338 struct vhost_dev *dev = data;
339 struct vhost_work *work, *work_next;
340 struct llist_node *node;
341 mm_segment_t oldfs = get_fs();
342
343 set_fs(USER_DS);
344 use_mm(dev->mm);
345
346 for (;;) {
347 /* mb paired w/ kthread_stop */
348 set_current_state(TASK_INTERRUPTIBLE);
349
350 if (kthread_should_stop()) {
351 __set_current_state(TASK_RUNNING);
352 break;
353 }
354
355 node = llist_del_all(&dev->work_list);
356 if (!node)
357 schedule();
358
359 node = llist_reverse_order(node);
360 /* make sure flag is seen after deletion */
361 smp_wmb();
362 llist_for_each_entry_safe(work, work_next, node, node) {
363 clear_bit(VHOST_WORK_QUEUED, &work->flags);
364 __set_current_state(TASK_RUNNING);
365 work->fn(work);
366 if (need_resched())
367 schedule();
368 }
369 }
370 unuse_mm(dev->mm);
371 set_fs(oldfs);
372 return 0;
373 }
374
375 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
376 {
377 kfree(vq->indirect);
378 vq->indirect = NULL;
379 kfree(vq->log);
380 vq->log = NULL;
381 kfree(vq->heads);
382 vq->heads = NULL;
383 }
384
385 /* Helper to allocate iovec buffers for all vqs. */
386 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
387 {
388 struct vhost_virtqueue *vq;
389 int i;
390
391 for (i = 0; i < dev->nvqs; ++i) {
392 vq = dev->vqs[i];
393 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
394 GFP_KERNEL);
395 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
396 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
397 if (!vq->indirect || !vq->log || !vq->heads)
398 goto err_nomem;
399 }
400 return 0;
401
402 err_nomem:
403 for (; i >= 0; --i)
404 vhost_vq_free_iovecs(dev->vqs[i]);
405 return -ENOMEM;
406 }
407
408 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
409 {
410 int i;
411
412 for (i = 0; i < dev->nvqs; ++i)
413 vhost_vq_free_iovecs(dev->vqs[i]);
414 }
415
416 void vhost_dev_init(struct vhost_dev *dev,
417 struct vhost_virtqueue **vqs, int nvqs)
418 {
419 struct vhost_virtqueue *vq;
420 int i;
421
422 dev->vqs = vqs;
423 dev->nvqs = nvqs;
424 mutex_init(&dev->mutex);
425 dev->log_ctx = NULL;
426 dev->log_file = NULL;
427 dev->umem = NULL;
428 dev->iotlb = NULL;
429 dev->mm = NULL;
430 dev->worker = NULL;
431 init_llist_head(&dev->work_list);
432 init_waitqueue_head(&dev->wait);
433 INIT_LIST_HEAD(&dev->read_list);
434 INIT_LIST_HEAD(&dev->pending_list);
435 spin_lock_init(&dev->iotlb_lock);
436
437
438 for (i = 0; i < dev->nvqs; ++i) {
439 vq = dev->vqs[i];
440 vq->log = NULL;
441 vq->indirect = NULL;
442 vq->heads = NULL;
443 vq->dev = dev;
444 mutex_init(&vq->mutex);
445 vhost_vq_reset(dev, vq);
446 if (vq->handle_kick)
447 vhost_poll_init(&vq->poll, vq->handle_kick,
448 POLLIN, dev);
449 }
450 }
451 EXPORT_SYMBOL_GPL(vhost_dev_init);
452
453 /* Caller should have device mutex */
454 long vhost_dev_check_owner(struct vhost_dev *dev)
455 {
456 /* Are you the owner? If not, I don't think you mean to do that */
457 return dev->mm == current->mm ? 0 : -EPERM;
458 }
459 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
460
461 struct vhost_attach_cgroups_struct {
462 struct vhost_work work;
463 struct task_struct *owner;
464 int ret;
465 };
466
467 static void vhost_attach_cgroups_work(struct vhost_work *work)
468 {
469 struct vhost_attach_cgroups_struct *s;
470
471 s = container_of(work, struct vhost_attach_cgroups_struct, work);
472 s->ret = cgroup_attach_task_all(s->owner, current);
473 }
474
475 static int vhost_attach_cgroups(struct vhost_dev *dev)
476 {
477 struct vhost_attach_cgroups_struct attach;
478
479 attach.owner = current;
480 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
481 vhost_work_queue(dev, &attach.work);
482 vhost_work_flush(dev, &attach.work);
483 return attach.ret;
484 }
485
486 /* Caller should have device mutex */
487 bool vhost_dev_has_owner(struct vhost_dev *dev)
488 {
489 return dev->mm;
490 }
491 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
492
493 /* Caller should have device mutex */
494 long vhost_dev_set_owner(struct vhost_dev *dev)
495 {
496 struct task_struct *worker;
497 int err;
498
499 /* Is there an owner already? */
500 if (vhost_dev_has_owner(dev)) {
501 err = -EBUSY;
502 goto err_mm;
503 }
504
505 /* No owner, become one */
506 dev->mm = get_task_mm(current);
507 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
508 if (IS_ERR(worker)) {
509 err = PTR_ERR(worker);
510 goto err_worker;
511 }
512
513 dev->worker = worker;
514 wake_up_process(worker); /* avoid contributing to loadavg */
515
516 err = vhost_attach_cgroups(dev);
517 if (err)
518 goto err_cgroup;
519
520 err = vhost_dev_alloc_iovecs(dev);
521 if (err)
522 goto err_cgroup;
523
524 return 0;
525 err_cgroup:
526 kthread_stop(worker);
527 dev->worker = NULL;
528 err_worker:
529 if (dev->mm)
530 mmput(dev->mm);
531 dev->mm = NULL;
532 err_mm:
533 return err;
534 }
535 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
536
537 static void *vhost_kvzalloc(unsigned long size)
538 {
539 void *n = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
540
541 if (!n)
542 n = vzalloc(size);
543 return n;
544 }
545
546 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
547 {
548 return vhost_kvzalloc(sizeof(struct vhost_umem));
549 }
550 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
551
552 /* Caller should have device mutex */
553 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
554 {
555 int i;
556
557 vhost_dev_cleanup(dev, true);
558
559 /* Restore memory to default empty mapping. */
560 INIT_LIST_HEAD(&umem->umem_list);
561 dev->umem = umem;
562 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
563 * VQs aren't running.
564 */
565 for (i = 0; i < dev->nvqs; ++i)
566 dev->vqs[i]->umem = umem;
567 }
568 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
569
570 void vhost_dev_stop(struct vhost_dev *dev)
571 {
572 int i;
573
574 for (i = 0; i < dev->nvqs; ++i) {
575 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
576 vhost_poll_stop(&dev->vqs[i]->poll);
577 vhost_poll_flush(&dev->vqs[i]->poll);
578 }
579 }
580 }
581 EXPORT_SYMBOL_GPL(vhost_dev_stop);
582
583 static void vhost_umem_free(struct vhost_umem *umem,
584 struct vhost_umem_node *node)
585 {
586 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
587 list_del(&node->link);
588 kfree(node);
589 umem->numem--;
590 }
591
592 static void vhost_umem_clean(struct vhost_umem *umem)
593 {
594 struct vhost_umem_node *node, *tmp;
595
596 if (!umem)
597 return;
598
599 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
600 vhost_umem_free(umem, node);
601
602 kvfree(umem);
603 }
604
605 static void vhost_clear_msg(struct vhost_dev *dev)
606 {
607 struct vhost_msg_node *node, *n;
608
609 spin_lock(&dev->iotlb_lock);
610
611 list_for_each_entry_safe(node, n, &dev->read_list, node) {
612 list_del(&node->node);
613 kfree(node);
614 }
615
616 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
617 list_del(&node->node);
618 kfree(node);
619 }
620
621 spin_unlock(&dev->iotlb_lock);
622 }
623
624 /* Caller should have device mutex if and only if locked is set */
625 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
626 {
627 int i;
628
629 for (i = 0; i < dev->nvqs; ++i) {
630 if (dev->vqs[i]->error_ctx)
631 eventfd_ctx_put(dev->vqs[i]->error_ctx);
632 if (dev->vqs[i]->error)
633 fput(dev->vqs[i]->error);
634 if (dev->vqs[i]->kick)
635 fput(dev->vqs[i]->kick);
636 if (dev->vqs[i]->call_ctx)
637 eventfd_ctx_put(dev->vqs[i]->call_ctx);
638 if (dev->vqs[i]->call)
639 fput(dev->vqs[i]->call);
640 vhost_vq_reset(dev, dev->vqs[i]);
641 }
642 vhost_dev_free_iovecs(dev);
643 if (dev->log_ctx)
644 eventfd_ctx_put(dev->log_ctx);
645 dev->log_ctx = NULL;
646 if (dev->log_file)
647 fput(dev->log_file);
648 dev->log_file = NULL;
649 /* No one will access memory at this point */
650 vhost_umem_clean(dev->umem);
651 dev->umem = NULL;
652 vhost_umem_clean(dev->iotlb);
653 dev->iotlb = NULL;
654 vhost_clear_msg(dev);
655 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
656 WARN_ON(!llist_empty(&dev->work_list));
657 if (dev->worker) {
658 kthread_stop(dev->worker);
659 dev->worker = NULL;
660 }
661 if (dev->mm)
662 mmput(dev->mm);
663 dev->mm = NULL;
664 }
665 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
666
667 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
668 {
669 u64 a = addr / VHOST_PAGE_SIZE / 8;
670
671 /* Make sure 64 bit math will not overflow. */
672 if (a > ULONG_MAX - (unsigned long)log_base ||
673 a + (unsigned long)log_base > ULONG_MAX)
674 return 0;
675
676 return access_ok(VERIFY_WRITE, log_base + a,
677 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
678 }
679
680 static bool vhost_overflow(u64 uaddr, u64 size)
681 {
682 /* Make sure 64 bit math will not overflow. */
683 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
684 }
685
686 /* Caller should have vq mutex and device mutex. */
687 static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
688 int log_all)
689 {
690 struct vhost_umem_node *node;
691
692 if (!umem)
693 return 0;
694
695 list_for_each_entry(node, &umem->umem_list, link) {
696 unsigned long a = node->userspace_addr;
697
698 if (vhost_overflow(node->userspace_addr, node->size))
699 return 0;
700
701
702 if (!access_ok(VERIFY_WRITE, (void __user *)a,
703 node->size))
704 return 0;
705 else if (log_all && !log_access_ok(log_base,
706 node->start,
707 node->size))
708 return 0;
709 }
710 return 1;
711 }
712
713 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
714 u64 addr, unsigned int size,
715 int type)
716 {
717 const struct vhost_umem_node *node = vq->meta_iotlb[type];
718
719 if (!node)
720 return NULL;
721
722 return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
723 }
724
725 /* Can we switch to this memory table? */
726 /* Caller should have device mutex but not vq mutex */
727 static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
728 int log_all)
729 {
730 int i;
731
732 for (i = 0; i < d->nvqs; ++i) {
733 int ok;
734 bool log;
735
736 mutex_lock(&d->vqs[i]->mutex);
737 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
738 /* If ring is inactive, will check when it's enabled. */
739 if (d->vqs[i]->private_data)
740 ok = vq_memory_access_ok(d->vqs[i]->log_base,
741 umem, log);
742 else
743 ok = 1;
744 mutex_unlock(&d->vqs[i]->mutex);
745 if (!ok)
746 return 0;
747 }
748 return 1;
749 }
750
751 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
752 struct iovec iov[], int iov_size, int access);
753
754 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
755 const void *from, unsigned size)
756 {
757 int ret;
758
759 if (!vq->iotlb)
760 return __copy_to_user(to, from, size);
761 else {
762 /* This function should be called after iotlb
763 * prefetch, which means we're sure that all vq
764 * could be access through iotlb. So -EAGAIN should
765 * not happen in this case.
766 */
767 struct iov_iter t;
768 void __user *uaddr = vhost_vq_meta_fetch(vq,
769 (u64)(uintptr_t)to, size,
770 VHOST_ADDR_DESC);
771
772 if (uaddr)
773 return __copy_to_user(uaddr, from, size);
774
775 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
776 ARRAY_SIZE(vq->iotlb_iov),
777 VHOST_ACCESS_WO);
778 if (ret < 0)
779 goto out;
780 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
781 ret = copy_to_iter(from, size, &t);
782 if (ret == size)
783 ret = 0;
784 }
785 out:
786 return ret;
787 }
788
789 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
790 void __user *from, unsigned size)
791 {
792 int ret;
793
794 if (!vq->iotlb)
795 return __copy_from_user(to, from, size);
796 else {
797 /* This function should be called after iotlb
798 * prefetch, which means we're sure that vq
799 * could be access through iotlb. So -EAGAIN should
800 * not happen in this case.
801 */
802 void __user *uaddr = vhost_vq_meta_fetch(vq,
803 (u64)(uintptr_t)from, size,
804 VHOST_ADDR_DESC);
805 struct iov_iter f;
806
807 if (uaddr)
808 return __copy_from_user(to, uaddr, size);
809
810 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
811 ARRAY_SIZE(vq->iotlb_iov),
812 VHOST_ACCESS_RO);
813 if (ret < 0) {
814 vq_err(vq, "IOTLB translation failure: uaddr "
815 "%p size 0x%llx\n", from,
816 (unsigned long long) size);
817 goto out;
818 }
819 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
820 ret = copy_from_iter(to, size, &f);
821 if (ret == size)
822 ret = 0;
823 }
824
825 out:
826 return ret;
827 }
828
829 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
830 void __user *addr, unsigned int size,
831 int type)
832 {
833 int ret;
834
835 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
836 ARRAY_SIZE(vq->iotlb_iov),
837 VHOST_ACCESS_RO);
838 if (ret < 0) {
839 vq_err(vq, "IOTLB translation failure: uaddr "
840 "%p size 0x%llx\n", addr,
841 (unsigned long long) size);
842 return NULL;
843 }
844
845 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
846 vq_err(vq, "Non atomic userspace memory access: uaddr "
847 "%p size 0x%llx\n", addr,
848 (unsigned long long) size);
849 return NULL;
850 }
851
852 return vq->iotlb_iov[0].iov_base;
853 }
854
855 /* This function should be called after iotlb
856 * prefetch, which means we're sure that vq
857 * could be access through iotlb. So -EAGAIN should
858 * not happen in this case.
859 */
860 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
861 void *addr, unsigned int size,
862 int type)
863 {
864 void __user *uaddr = vhost_vq_meta_fetch(vq,
865 (u64)(uintptr_t)addr, size, type);
866 if (uaddr)
867 return uaddr;
868
869 return __vhost_get_user_slow(vq, addr, size, type);
870 }
871
872 #define vhost_put_user(vq, x, ptr) \
873 ({ \
874 int ret = -EFAULT; \
875 if (!vq->iotlb) { \
876 ret = __put_user(x, ptr); \
877 } else { \
878 __typeof__(ptr) to = \
879 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
880 sizeof(*ptr), VHOST_ADDR_USED); \
881 if (to != NULL) \
882 ret = __put_user(x, to); \
883 else \
884 ret = -EFAULT; \
885 } \
886 ret; \
887 })
888
889 #define vhost_get_user(vq, x, ptr, type) \
890 ({ \
891 int ret; \
892 if (!vq->iotlb) { \
893 ret = __get_user(x, ptr); \
894 } else { \
895 __typeof__(ptr) from = \
896 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
897 sizeof(*ptr), \
898 type); \
899 if (from != NULL) \
900 ret = __get_user(x, from); \
901 else \
902 ret = -EFAULT; \
903 } \
904 ret; \
905 })
906
907 #define vhost_get_avail(vq, x, ptr) \
908 vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
909
910 #define vhost_get_used(vq, x, ptr) \
911 vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
912
913 static void vhost_dev_lock_vqs(struct vhost_dev *d)
914 {
915 int i = 0;
916 for (i = 0; i < d->nvqs; ++i)
917 mutex_lock(&d->vqs[i]->mutex);
918 }
919
920 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
921 {
922 int i = 0;
923 for (i = 0; i < d->nvqs; ++i)
924 mutex_unlock(&d->vqs[i]->mutex);
925 }
926
927 static int vhost_new_umem_range(struct vhost_umem *umem,
928 u64 start, u64 size, u64 end,
929 u64 userspace_addr, int perm)
930 {
931 struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
932
933 if (!node)
934 return -ENOMEM;
935
936 if (umem->numem == max_iotlb_entries) {
937 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
938 vhost_umem_free(umem, tmp);
939 }
940
941 node->start = start;
942 node->size = size;
943 node->last = end;
944 node->userspace_addr = userspace_addr;
945 node->perm = perm;
946 INIT_LIST_HEAD(&node->link);
947 list_add_tail(&node->link, &umem->umem_list);
948 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
949 umem->numem++;
950
951 return 0;
952 }
953
954 static void vhost_del_umem_range(struct vhost_umem *umem,
955 u64 start, u64 end)
956 {
957 struct vhost_umem_node *node;
958
959 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
960 start, end)))
961 vhost_umem_free(umem, node);
962 }
963
964 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
965 struct vhost_iotlb_msg *msg)
966 {
967 struct vhost_msg_node *node, *n;
968
969 spin_lock(&d->iotlb_lock);
970
971 list_for_each_entry_safe(node, n, &d->pending_list, node) {
972 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
973 if (msg->iova <= vq_msg->iova &&
974 msg->iova + msg->size - 1 > vq_msg->iova &&
975 vq_msg->type == VHOST_IOTLB_MISS) {
976 vhost_poll_queue(&node->vq->poll);
977 list_del(&node->node);
978 kfree(node);
979 }
980 }
981
982 spin_unlock(&d->iotlb_lock);
983 }
984
985 static int umem_access_ok(u64 uaddr, u64 size, int access)
986 {
987 unsigned long a = uaddr;
988
989 /* Make sure 64 bit math will not overflow. */
990 if (vhost_overflow(uaddr, size))
991 return -EFAULT;
992
993 if ((access & VHOST_ACCESS_RO) &&
994 !access_ok(VERIFY_READ, (void __user *)a, size))
995 return -EFAULT;
996 if ((access & VHOST_ACCESS_WO) &&
997 !access_ok(VERIFY_WRITE, (void __user *)a, size))
998 return -EFAULT;
999 return 0;
1000 }
1001
1002 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
1003 struct vhost_iotlb_msg *msg)
1004 {
1005 int ret = 0;
1006
1007 vhost_dev_lock_vqs(dev);
1008 switch (msg->type) {
1009 case VHOST_IOTLB_UPDATE:
1010 if (!dev->iotlb) {
1011 ret = -EFAULT;
1012 break;
1013 }
1014 if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1015 ret = -EFAULT;
1016 break;
1017 }
1018 vhost_vq_meta_reset(dev);
1019 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
1020 msg->iova + msg->size - 1,
1021 msg->uaddr, msg->perm)) {
1022 ret = -ENOMEM;
1023 break;
1024 }
1025 vhost_iotlb_notify_vq(dev, msg);
1026 break;
1027 case VHOST_IOTLB_INVALIDATE:
1028 vhost_vq_meta_reset(dev);
1029 vhost_del_umem_range(dev->iotlb, msg->iova,
1030 msg->iova + msg->size - 1);
1031 break;
1032 default:
1033 ret = -EINVAL;
1034 break;
1035 }
1036
1037 vhost_dev_unlock_vqs(dev);
1038 return ret;
1039 }
1040 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1041 struct iov_iter *from)
1042 {
1043 struct vhost_msg_node node;
1044 unsigned size = sizeof(struct vhost_msg);
1045 size_t ret;
1046 int err;
1047
1048 if (iov_iter_count(from) < size)
1049 return 0;
1050 ret = copy_from_iter(&node.msg, size, from);
1051 if (ret != size)
1052 goto done;
1053
1054 switch (node.msg.type) {
1055 case VHOST_IOTLB_MSG:
1056 err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
1057 if (err)
1058 ret = err;
1059 break;
1060 default:
1061 ret = -EINVAL;
1062 break;
1063 }
1064
1065 done:
1066 return ret;
1067 }
1068 EXPORT_SYMBOL(vhost_chr_write_iter);
1069
1070 unsigned int vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1071 poll_table *wait)
1072 {
1073 unsigned int mask = 0;
1074
1075 poll_wait(file, &dev->wait, wait);
1076
1077 if (!list_empty(&dev->read_list))
1078 mask |= POLLIN | POLLRDNORM;
1079
1080 return mask;
1081 }
1082 EXPORT_SYMBOL(vhost_chr_poll);
1083
1084 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1085 int noblock)
1086 {
1087 DEFINE_WAIT(wait);
1088 struct vhost_msg_node *node;
1089 ssize_t ret = 0;
1090 unsigned size = sizeof(struct vhost_msg);
1091
1092 if (iov_iter_count(to) < size)
1093 return 0;
1094
1095 while (1) {
1096 if (!noblock)
1097 prepare_to_wait(&dev->wait, &wait,
1098 TASK_INTERRUPTIBLE);
1099
1100 node = vhost_dequeue_msg(dev, &dev->read_list);
1101 if (node)
1102 break;
1103 if (noblock) {
1104 ret = -EAGAIN;
1105 break;
1106 }
1107 if (signal_pending(current)) {
1108 ret = -ERESTARTSYS;
1109 break;
1110 }
1111 if (!dev->iotlb) {
1112 ret = -EBADFD;
1113 break;
1114 }
1115
1116 schedule();
1117 }
1118
1119 if (!noblock)
1120 finish_wait(&dev->wait, &wait);
1121
1122 if (node) {
1123 ret = copy_to_iter(&node->msg, size, to);
1124
1125 if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {
1126 kfree(node);
1127 return ret;
1128 }
1129
1130 vhost_enqueue_msg(dev, &dev->pending_list, node);
1131 }
1132
1133 return ret;
1134 }
1135 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1136
1137 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1138 {
1139 struct vhost_dev *dev = vq->dev;
1140 struct vhost_msg_node *node;
1141 struct vhost_iotlb_msg *msg;
1142
1143 node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
1144 if (!node)
1145 return -ENOMEM;
1146
1147 msg = &node->msg.iotlb;
1148 msg->type = VHOST_IOTLB_MISS;
1149 msg->iova = iova;
1150 msg->perm = access;
1151
1152 vhost_enqueue_msg(dev, &dev->read_list, node);
1153
1154 return 0;
1155 }
1156
1157 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1158 struct vring_desc __user *desc,
1159 struct vring_avail __user *avail,
1160 struct vring_used __user *used)
1161
1162 {
1163 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1164
1165 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
1166 access_ok(VERIFY_READ, avail,
1167 sizeof *avail + num * sizeof *avail->ring + s) &&
1168 access_ok(VERIFY_WRITE, used,
1169 sizeof *used + num * sizeof *used->ring + s);
1170 }
1171
1172 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1173 const struct vhost_umem_node *node,
1174 int type)
1175 {
1176 int access = (type == VHOST_ADDR_USED) ?
1177 VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1178
1179 if (likely(node->perm & access))
1180 vq->meta_iotlb[type] = node;
1181 }
1182
1183 static int iotlb_access_ok(struct vhost_virtqueue *vq,
1184 int access, u64 addr, u64 len, int type)
1185 {
1186 const struct vhost_umem_node *node;
1187 struct vhost_umem *umem = vq->iotlb;
1188 u64 s = 0, size, orig_addr = addr;
1189
1190 if (vhost_vq_meta_fetch(vq, addr, len, type))
1191 return true;
1192
1193 while (len > s) {
1194 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1195 addr,
1196 addr + len - 1);
1197 if (node == NULL || node->start > addr) {
1198 vhost_iotlb_miss(vq, addr, access);
1199 return false;
1200 } else if (!(node->perm & access)) {
1201 /* Report the possible access violation by
1202 * request another translation from userspace.
1203 */
1204 return false;
1205 }
1206
1207 size = node->size - addr + node->start;
1208
1209 if (orig_addr == addr && size >= len)
1210 vhost_vq_meta_update(vq, node, type);
1211
1212 s += size;
1213 addr += size;
1214 }
1215
1216 return true;
1217 }
1218
1219 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1220 {
1221 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1222 unsigned int num = vq->num;
1223
1224 if (!vq->iotlb)
1225 return 1;
1226
1227 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1228 num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
1229 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1230 sizeof *vq->avail +
1231 num * sizeof(*vq->avail->ring) + s,
1232 VHOST_ADDR_AVAIL) &&
1233 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1234 sizeof *vq->used +
1235 num * sizeof(*vq->used->ring) + s,
1236 VHOST_ADDR_USED);
1237 }
1238 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1239
1240 /* Can we log writes? */
1241 /* Caller should have device mutex but not vq mutex */
1242 int vhost_log_access_ok(struct vhost_dev *dev)
1243 {
1244 return memory_access_ok(dev, dev->umem, 1);
1245 }
1246 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1247
1248 /* Verify access for write logging. */
1249 /* Caller should have vq mutex and device mutex */
1250 static int vq_log_access_ok(struct vhost_virtqueue *vq,
1251 void __user *log_base)
1252 {
1253 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1254
1255 return vq_memory_access_ok(log_base, vq->umem,
1256 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1257 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1258 sizeof *vq->used +
1259 vq->num * sizeof *vq->used->ring + s));
1260 }
1261
1262 /* Can we start vq? */
1263 /* Caller should have vq mutex and device mutex */
1264 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
1265 {
1266 if (vq->iotlb) {
1267 /* When device IOTLB was used, the access validation
1268 * will be validated during prefetching.
1269 */
1270 return 1;
1271 }
1272 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
1273 vq_log_access_ok(vq, vq->log_base);
1274 }
1275 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1276
1277 static struct vhost_umem *vhost_umem_alloc(void)
1278 {
1279 struct vhost_umem *umem = vhost_kvzalloc(sizeof(*umem));
1280
1281 if (!umem)
1282 return NULL;
1283
1284 umem->umem_tree = RB_ROOT;
1285 umem->numem = 0;
1286 INIT_LIST_HEAD(&umem->umem_list);
1287
1288 return umem;
1289 }
1290
1291 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1292 {
1293 struct vhost_memory mem, *newmem;
1294 struct vhost_memory_region *region;
1295 struct vhost_umem *newumem, *oldumem;
1296 unsigned long size = offsetof(struct vhost_memory, regions);
1297 int i;
1298
1299 if (copy_from_user(&mem, m, size))
1300 return -EFAULT;
1301 if (mem.padding)
1302 return -EOPNOTSUPP;
1303 if (mem.nregions > max_mem_regions)
1304 return -E2BIG;
1305 newmem = vhost_kvzalloc(size + mem.nregions * sizeof(*m->regions));
1306 if (!newmem)
1307 return -ENOMEM;
1308
1309 memcpy(newmem, &mem, size);
1310 if (copy_from_user(newmem->regions, m->regions,
1311 mem.nregions * sizeof *m->regions)) {
1312 kvfree(newmem);
1313 return -EFAULT;
1314 }
1315
1316 newumem = vhost_umem_alloc();
1317 if (!newumem) {
1318 kvfree(newmem);
1319 return -ENOMEM;
1320 }
1321
1322 for (region = newmem->regions;
1323 region < newmem->regions + mem.nregions;
1324 region++) {
1325 if (vhost_new_umem_range(newumem,
1326 region->guest_phys_addr,
1327 region->memory_size,
1328 region->guest_phys_addr +
1329 region->memory_size - 1,
1330 region->userspace_addr,
1331 VHOST_ACCESS_RW))
1332 goto err;
1333 }
1334
1335 if (!memory_access_ok(d, newumem, 0))
1336 goto err;
1337
1338 oldumem = d->umem;
1339 d->umem = newumem;
1340
1341 /* All memory accesses are done under some VQ mutex. */
1342 for (i = 0; i < d->nvqs; ++i) {
1343 mutex_lock(&d->vqs[i]->mutex);
1344 d->vqs[i]->umem = newumem;
1345 mutex_unlock(&d->vqs[i]->mutex);
1346 }
1347
1348 kvfree(newmem);
1349 vhost_umem_clean(oldumem);
1350 return 0;
1351
1352 err:
1353 vhost_umem_clean(newumem);
1354 kvfree(newmem);
1355 return -EFAULT;
1356 }
1357
1358 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
1359 {
1360 struct file *eventfp, *filep = NULL;
1361 bool pollstart = false, pollstop = false;
1362 struct eventfd_ctx *ctx = NULL;
1363 u32 __user *idxp = argp;
1364 struct vhost_virtqueue *vq;
1365 struct vhost_vring_state s;
1366 struct vhost_vring_file f;
1367 struct vhost_vring_addr a;
1368 u32 idx;
1369 long r;
1370
1371 r = get_user(idx, idxp);
1372 if (r < 0)
1373 return r;
1374 if (idx >= d->nvqs)
1375 return -ENOBUFS;
1376
1377 vq = d->vqs[idx];
1378
1379 mutex_lock(&vq->mutex);
1380
1381 switch (ioctl) {
1382 case VHOST_SET_VRING_NUM:
1383 /* Resizing ring with an active backend?
1384 * You don't want to do that. */
1385 if (vq->private_data) {
1386 r = -EBUSY;
1387 break;
1388 }
1389 if (copy_from_user(&s, argp, sizeof s)) {
1390 r = -EFAULT;
1391 break;
1392 }
1393 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1394 r = -EINVAL;
1395 break;
1396 }
1397 vq->num = s.num;
1398 break;
1399 case VHOST_SET_VRING_BASE:
1400 /* Moving base with an active backend?
1401 * You don't want to do that. */
1402 if (vq->private_data) {
1403 r = -EBUSY;
1404 break;
1405 }
1406 if (copy_from_user(&s, argp, sizeof s)) {
1407 r = -EFAULT;
1408 break;
1409 }
1410 if (s.num > 0xffff) {
1411 r = -EINVAL;
1412 break;
1413 }
1414 vq->last_avail_idx = vq->last_used_event = s.num;
1415 /* Forget the cached index value. */
1416 vq->avail_idx = vq->last_avail_idx;
1417 break;
1418 case VHOST_GET_VRING_BASE:
1419 s.index = idx;
1420 s.num = vq->last_avail_idx;
1421 if (copy_to_user(argp, &s, sizeof s))
1422 r = -EFAULT;
1423 break;
1424 case VHOST_SET_VRING_ADDR:
1425 if (copy_from_user(&a, argp, sizeof a)) {
1426 r = -EFAULT;
1427 break;
1428 }
1429 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1430 r = -EOPNOTSUPP;
1431 break;
1432 }
1433 /* For 32bit, verify that the top 32bits of the user
1434 data are set to zero. */
1435 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1436 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1437 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1438 r = -EFAULT;
1439 break;
1440 }
1441
1442 /* Make sure it's safe to cast pointers to vring types. */
1443 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1444 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1445 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1446 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1447 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1448 r = -EINVAL;
1449 break;
1450 }
1451
1452 /* We only verify access here if backend is configured.
1453 * If it is not, we don't as size might not have been setup.
1454 * We will verify when backend is configured. */
1455 if (vq->private_data) {
1456 if (!vq_access_ok(vq, vq->num,
1457 (void __user *)(unsigned long)a.desc_user_addr,
1458 (void __user *)(unsigned long)a.avail_user_addr,
1459 (void __user *)(unsigned long)a.used_user_addr)) {
1460 r = -EINVAL;
1461 break;
1462 }
1463
1464 /* Also validate log access for used ring if enabled. */
1465 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1466 !log_access_ok(vq->log_base, a.log_guest_addr,
1467 sizeof *vq->used +
1468 vq->num * sizeof *vq->used->ring)) {
1469 r = -EINVAL;
1470 break;
1471 }
1472 }
1473
1474 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1475 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1476 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1477 vq->log_addr = a.log_guest_addr;
1478 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1479 break;
1480 case VHOST_SET_VRING_KICK:
1481 if (copy_from_user(&f, argp, sizeof f)) {
1482 r = -EFAULT;
1483 break;
1484 }
1485 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1486 if (IS_ERR(eventfp)) {
1487 r = PTR_ERR(eventfp);
1488 break;
1489 }
1490 if (eventfp != vq->kick) {
1491 pollstop = (filep = vq->kick) != NULL;
1492 pollstart = (vq->kick = eventfp) != NULL;
1493 } else
1494 filep = eventfp;
1495 break;
1496 case VHOST_SET_VRING_CALL:
1497 if (copy_from_user(&f, argp, sizeof f)) {
1498 r = -EFAULT;
1499 break;
1500 }
1501 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1502 if (IS_ERR(eventfp)) {
1503 r = PTR_ERR(eventfp);
1504 break;
1505 }
1506 if (eventfp != vq->call) {
1507 filep = vq->call;
1508 ctx = vq->call_ctx;
1509 vq->call = eventfp;
1510 vq->call_ctx = eventfp ?
1511 eventfd_ctx_fileget(eventfp) : NULL;
1512 } else
1513 filep = eventfp;
1514 break;
1515 case VHOST_SET_VRING_ERR:
1516 if (copy_from_user(&f, argp, sizeof f)) {
1517 r = -EFAULT;
1518 break;
1519 }
1520 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1521 if (IS_ERR(eventfp)) {
1522 r = PTR_ERR(eventfp);
1523 break;
1524 }
1525 if (eventfp != vq->error) {
1526 filep = vq->error;
1527 vq->error = eventfp;
1528 ctx = vq->error_ctx;
1529 vq->error_ctx = eventfp ?
1530 eventfd_ctx_fileget(eventfp) : NULL;
1531 } else
1532 filep = eventfp;
1533 break;
1534 case VHOST_SET_VRING_ENDIAN:
1535 r = vhost_set_vring_endian(vq, argp);
1536 break;
1537 case VHOST_GET_VRING_ENDIAN:
1538 r = vhost_get_vring_endian(vq, idx, argp);
1539 break;
1540 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1541 if (copy_from_user(&s, argp, sizeof(s))) {
1542 r = -EFAULT;
1543 break;
1544 }
1545 vq->busyloop_timeout = s.num;
1546 break;
1547 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1548 s.index = idx;
1549 s.num = vq->busyloop_timeout;
1550 if (copy_to_user(argp, &s, sizeof(s)))
1551 r = -EFAULT;
1552 break;
1553 default:
1554 r = -ENOIOCTLCMD;
1555 }
1556
1557 if (pollstop && vq->handle_kick)
1558 vhost_poll_stop(&vq->poll);
1559
1560 if (ctx)
1561 eventfd_ctx_put(ctx);
1562 if (filep)
1563 fput(filep);
1564
1565 if (pollstart && vq->handle_kick)
1566 r = vhost_poll_start(&vq->poll, vq->kick);
1567
1568 mutex_unlock(&vq->mutex);
1569
1570 if (pollstop && vq->handle_kick)
1571 vhost_poll_flush(&vq->poll);
1572 return r;
1573 }
1574 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1575
1576 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1577 {
1578 struct vhost_umem *niotlb, *oiotlb;
1579 int i;
1580
1581 niotlb = vhost_umem_alloc();
1582 if (!niotlb)
1583 return -ENOMEM;
1584
1585 oiotlb = d->iotlb;
1586 d->iotlb = niotlb;
1587
1588 for (i = 0; i < d->nvqs; ++i) {
1589 mutex_lock(&d->vqs[i]->mutex);
1590 d->vqs[i]->iotlb = niotlb;
1591 mutex_unlock(&d->vqs[i]->mutex);
1592 }
1593
1594 vhost_umem_clean(oiotlb);
1595
1596 return 0;
1597 }
1598 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1599
1600 /* Caller must have device mutex */
1601 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1602 {
1603 struct file *eventfp, *filep = NULL;
1604 struct eventfd_ctx *ctx = NULL;
1605 u64 p;
1606 long r;
1607 int i, fd;
1608
1609 /* If you are not the owner, you can become one */
1610 if (ioctl == VHOST_SET_OWNER) {
1611 r = vhost_dev_set_owner(d);
1612 goto done;
1613 }
1614
1615 /* You must be the owner to do anything else */
1616 r = vhost_dev_check_owner(d);
1617 if (r)
1618 goto done;
1619
1620 switch (ioctl) {
1621 case VHOST_SET_MEM_TABLE:
1622 r = vhost_set_memory(d, argp);
1623 break;
1624 case VHOST_SET_LOG_BASE:
1625 if (copy_from_user(&p, argp, sizeof p)) {
1626 r = -EFAULT;
1627 break;
1628 }
1629 if ((u64)(unsigned long)p != p) {
1630 r = -EFAULT;
1631 break;
1632 }
1633 for (i = 0; i < d->nvqs; ++i) {
1634 struct vhost_virtqueue *vq;
1635 void __user *base = (void __user *)(unsigned long)p;
1636 vq = d->vqs[i];
1637 mutex_lock(&vq->mutex);
1638 /* If ring is inactive, will check when it's enabled. */
1639 if (vq->private_data && !vq_log_access_ok(vq, base))
1640 r = -EFAULT;
1641 else
1642 vq->log_base = base;
1643 mutex_unlock(&vq->mutex);
1644 }
1645 break;
1646 case VHOST_SET_LOG_FD:
1647 r = get_user(fd, (int __user *)argp);
1648 if (r < 0)
1649 break;
1650 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
1651 if (IS_ERR(eventfp)) {
1652 r = PTR_ERR(eventfp);
1653 break;
1654 }
1655 if (eventfp != d->log_file) {
1656 filep = d->log_file;
1657 d->log_file = eventfp;
1658 ctx = d->log_ctx;
1659 d->log_ctx = eventfp ?
1660 eventfd_ctx_fileget(eventfp) : NULL;
1661 } else
1662 filep = eventfp;
1663 for (i = 0; i < d->nvqs; ++i) {
1664 mutex_lock(&d->vqs[i]->mutex);
1665 d->vqs[i]->log_ctx = d->log_ctx;
1666 mutex_unlock(&d->vqs[i]->mutex);
1667 }
1668 if (ctx)
1669 eventfd_ctx_put(ctx);
1670 if (filep)
1671 fput(filep);
1672 break;
1673 default:
1674 r = -ENOIOCTLCMD;
1675 break;
1676 }
1677 done:
1678 return r;
1679 }
1680 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1681
1682 /* TODO: This is really inefficient. We need something like get_user()
1683 * (instruction directly accesses the data, with an exception table entry
1684 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1685 */
1686 static int set_bit_to_user(int nr, void __user *addr)
1687 {
1688 unsigned long log = (unsigned long)addr;
1689 struct page *page;
1690 void *base;
1691 int bit = nr + (log % PAGE_SIZE) * 8;
1692 int r;
1693
1694 r = get_user_pages_fast(log, 1, 1, &page);
1695 if (r < 0)
1696 return r;
1697 BUG_ON(r != 1);
1698 base = kmap_atomic(page);
1699 set_bit(bit, base);
1700 kunmap_atomic(base);
1701 set_page_dirty_lock(page);
1702 put_page(page);
1703 return 0;
1704 }
1705
1706 static int log_write(void __user *log_base,
1707 u64 write_address, u64 write_length)
1708 {
1709 u64 write_page = write_address / VHOST_PAGE_SIZE;
1710 int r;
1711
1712 if (!write_length)
1713 return 0;
1714 write_length += write_address % VHOST_PAGE_SIZE;
1715 for (;;) {
1716 u64 base = (u64)(unsigned long)log_base;
1717 u64 log = base + write_page / 8;
1718 int bit = write_page % 8;
1719 if ((u64)(unsigned long)log != log)
1720 return -EFAULT;
1721 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1722 if (r < 0)
1723 return r;
1724 if (write_length <= VHOST_PAGE_SIZE)
1725 break;
1726 write_length -= VHOST_PAGE_SIZE;
1727 write_page += 1;
1728 }
1729 return r;
1730 }
1731
1732 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1733 unsigned int log_num, u64 len)
1734 {
1735 int i, r;
1736
1737 /* Make sure data written is seen before log. */
1738 smp_wmb();
1739 for (i = 0; i < log_num; ++i) {
1740 u64 l = min(log[i].len, len);
1741 r = log_write(vq->log_base, log[i].addr, l);
1742 if (r < 0)
1743 return r;
1744 len -= l;
1745 if (!len) {
1746 if (vq->log_ctx)
1747 eventfd_signal(vq->log_ctx, 1);
1748 return 0;
1749 }
1750 }
1751 /* Length written exceeds what we have stored. This is a bug. */
1752 BUG();
1753 return 0;
1754 }
1755 EXPORT_SYMBOL_GPL(vhost_log_write);
1756
1757 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1758 {
1759 void __user *used;
1760 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1761 &vq->used->flags) < 0)
1762 return -EFAULT;
1763 if (unlikely(vq->log_used)) {
1764 /* Make sure the flag is seen before log. */
1765 smp_wmb();
1766 /* Log used flag write. */
1767 used = &vq->used->flags;
1768 log_write(vq->log_base, vq->log_addr +
1769 (used - (void __user *)vq->used),
1770 sizeof vq->used->flags);
1771 if (vq->log_ctx)
1772 eventfd_signal(vq->log_ctx, 1);
1773 }
1774 return 0;
1775 }
1776
1777 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1778 {
1779 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1780 vhost_avail_event(vq)))
1781 return -EFAULT;
1782 if (unlikely(vq->log_used)) {
1783 void __user *used;
1784 /* Make sure the event is seen before log. */
1785 smp_wmb();
1786 /* Log avail event write */
1787 used = vhost_avail_event(vq);
1788 log_write(vq->log_base, vq->log_addr +
1789 (used - (void __user *)vq->used),
1790 sizeof *vhost_avail_event(vq));
1791 if (vq->log_ctx)
1792 eventfd_signal(vq->log_ctx, 1);
1793 }
1794 return 0;
1795 }
1796
1797 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1798 {
1799 __virtio16 last_used_idx;
1800 int r;
1801 bool is_le = vq->is_le;
1802
1803 if (!vq->private_data)
1804 return 0;
1805
1806 vhost_init_is_le(vq);
1807
1808 r = vhost_update_used_flags(vq);
1809 if (r)
1810 goto err;
1811 vq->signalled_used_valid = false;
1812 if (!vq->iotlb &&
1813 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1814 r = -EFAULT;
1815 goto err;
1816 }
1817 r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
1818 if (r) {
1819 vq_err(vq, "Can't access used idx at %p\n",
1820 &vq->used->idx);
1821 goto err;
1822 }
1823 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1824 return 0;
1825
1826 err:
1827 vq->is_le = is_le;
1828 return r;
1829 }
1830 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1831
1832 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1833 struct iovec iov[], int iov_size, int access)
1834 {
1835 const struct vhost_umem_node *node;
1836 struct vhost_dev *dev = vq->dev;
1837 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1838 struct iovec *_iov;
1839 u64 s = 0;
1840 int ret = 0;
1841
1842 while ((u64)len > s) {
1843 u64 size;
1844 if (unlikely(ret >= iov_size)) {
1845 ret = -ENOBUFS;
1846 break;
1847 }
1848
1849 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1850 addr, addr + len - 1);
1851 if (node == NULL || node->start > addr) {
1852 if (umem != dev->iotlb) {
1853 ret = -EFAULT;
1854 break;
1855 }
1856 ret = -EAGAIN;
1857 break;
1858 } else if (!(node->perm & access)) {
1859 ret = -EPERM;
1860 break;
1861 }
1862
1863 _iov = iov + ret;
1864 size = node->size - addr + node->start;
1865 _iov->iov_len = min((u64)len - s, size);
1866 _iov->iov_base = (void __user *)(unsigned long)
1867 (node->userspace_addr + addr - node->start);
1868 s += size;
1869 addr += size;
1870 ++ret;
1871 }
1872
1873 if (ret == -EAGAIN)
1874 vhost_iotlb_miss(vq, addr, access);
1875 return ret;
1876 }
1877
1878 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1879 * function returns the next descriptor in the chain,
1880 * or -1U if we're at the end. */
1881 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1882 {
1883 unsigned int next;
1884
1885 /* If this descriptor says it doesn't chain, we're done. */
1886 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1887 return -1U;
1888
1889 /* Check they're not leading us off end of descriptors. */
1890 next = vhost16_to_cpu(vq, desc->next);
1891 /* Make sure compiler knows to grab that: we don't want it changing! */
1892 /* We will use the result as an index in an array, so most
1893 * architectures only need a compiler barrier here. */
1894 read_barrier_depends();
1895
1896 return next;
1897 }
1898
1899 static int get_indirect(struct vhost_virtqueue *vq,
1900 struct iovec iov[], unsigned int iov_size,
1901 unsigned int *out_num, unsigned int *in_num,
1902 struct vhost_log *log, unsigned int *log_num,
1903 struct vring_desc *indirect)
1904 {
1905 struct vring_desc desc;
1906 unsigned int i = 0, count, found = 0;
1907 u32 len = vhost32_to_cpu(vq, indirect->len);
1908 struct iov_iter from;
1909 int ret, access;
1910
1911 /* Sanity check */
1912 if (unlikely(len % sizeof desc)) {
1913 vq_err(vq, "Invalid length in indirect descriptor: "
1914 "len 0x%llx not multiple of 0x%zx\n",
1915 (unsigned long long)len,
1916 sizeof desc);
1917 return -EINVAL;
1918 }
1919
1920 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1921 UIO_MAXIOV, VHOST_ACCESS_RO);
1922 if (unlikely(ret < 0)) {
1923 if (ret != -EAGAIN)
1924 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1925 return ret;
1926 }
1927 iov_iter_init(&from, READ, vq->indirect, ret, len);
1928
1929 /* We will use the result as an address to read from, so most
1930 * architectures only need a compiler barrier here. */
1931 read_barrier_depends();
1932
1933 count = len / sizeof desc;
1934 /* Buffers are chained via a 16 bit next field, so
1935 * we can have at most 2^16 of these. */
1936 if (unlikely(count > USHRT_MAX + 1)) {
1937 vq_err(vq, "Indirect buffer length too big: %d\n",
1938 indirect->len);
1939 return -E2BIG;
1940 }
1941
1942 do {
1943 unsigned iov_count = *in_num + *out_num;
1944 if (unlikely(++found > count)) {
1945 vq_err(vq, "Loop detected: last one at %u "
1946 "indirect size %u\n",
1947 i, count);
1948 return -EINVAL;
1949 }
1950 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1951 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1952 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1953 return -EINVAL;
1954 }
1955 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1956 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1957 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1958 return -EINVAL;
1959 }
1960
1961 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1962 access = VHOST_ACCESS_WO;
1963 else
1964 access = VHOST_ACCESS_RO;
1965
1966 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1967 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1968 iov_size - iov_count, access);
1969 if (unlikely(ret < 0)) {
1970 if (ret != -EAGAIN)
1971 vq_err(vq, "Translation failure %d indirect idx %d\n",
1972 ret, i);
1973 return ret;
1974 }
1975 /* If this is an input descriptor, increment that count. */
1976 if (access == VHOST_ACCESS_WO) {
1977 *in_num += ret;
1978 if (unlikely(log)) {
1979 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1980 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1981 ++*log_num;
1982 }
1983 } else {
1984 /* If it's an output descriptor, they're all supposed
1985 * to come before any input descriptors. */
1986 if (unlikely(*in_num)) {
1987 vq_err(vq, "Indirect descriptor "
1988 "has out after in: idx %d\n", i);
1989 return -EINVAL;
1990 }
1991 *out_num += ret;
1992 }
1993 } while ((i = next_desc(vq, &desc)) != -1);
1994 return 0;
1995 }
1996
1997 /* This looks in the virtqueue and for the first available buffer, and converts
1998 * it to an iovec for convenient access. Since descriptors consist of some
1999 * number of output then some number of input descriptors, it's actually two
2000 * iovecs, but we pack them into one and note how many of each there were.
2001 *
2002 * This function returns the descriptor number found, or vq->num (which is
2003 * never a valid descriptor number) if none was found. A negative code is
2004 * returned on error. */
2005 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2006 struct iovec iov[], unsigned int iov_size,
2007 unsigned int *out_num, unsigned int *in_num,
2008 struct vhost_log *log, unsigned int *log_num)
2009 {
2010 struct vring_desc desc;
2011 unsigned int i, head, found = 0;
2012 u16 last_avail_idx;
2013 __virtio16 avail_idx;
2014 __virtio16 ring_head;
2015 int ret, access;
2016
2017 /* Check it isn't doing very strange things with descriptor numbers. */
2018 last_avail_idx = vq->last_avail_idx;
2019
2020 if (vq->avail_idx == vq->last_avail_idx) {
2021 if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
2022 vq_err(vq, "Failed to access avail idx at %p\n",
2023 &vq->avail->idx);
2024 return -EFAULT;
2025 }
2026 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2027
2028 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2029 vq_err(vq, "Guest moved used index from %u to %u",
2030 last_avail_idx, vq->avail_idx);
2031 return -EFAULT;
2032 }
2033
2034 /* If there's nothing new since last we looked, return
2035 * invalid.
2036 */
2037 if (vq->avail_idx == last_avail_idx)
2038 return vq->num;
2039
2040 /* Only get avail ring entries after they have been
2041 * exposed by guest.
2042 */
2043 smp_rmb();
2044 }
2045
2046 /* Grab the next descriptor number they're advertising, and increment
2047 * the index we've seen. */
2048 if (unlikely(vhost_get_avail(vq, ring_head,
2049 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
2050 vq_err(vq, "Failed to read head: idx %d address %p\n",
2051 last_avail_idx,
2052 &vq->avail->ring[last_avail_idx % vq->num]);
2053 return -EFAULT;
2054 }
2055
2056 head = vhost16_to_cpu(vq, ring_head);
2057
2058 /* If their number is silly, that's an error. */
2059 if (unlikely(head >= vq->num)) {
2060 vq_err(vq, "Guest says index %u > %u is available",
2061 head, vq->num);
2062 return -EINVAL;
2063 }
2064
2065 /* When we start there are none of either input nor output. */
2066 *out_num = *in_num = 0;
2067 if (unlikely(log))
2068 *log_num = 0;
2069
2070 i = head;
2071 do {
2072 unsigned iov_count = *in_num + *out_num;
2073 if (unlikely(i >= vq->num)) {
2074 vq_err(vq, "Desc index is %u > %u, head = %u",
2075 i, vq->num, head);
2076 return -EINVAL;
2077 }
2078 if (unlikely(++found > vq->num)) {
2079 vq_err(vq, "Loop detected: last one at %u "
2080 "vq size %u head %u\n",
2081 i, vq->num, head);
2082 return -EINVAL;
2083 }
2084 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
2085 sizeof desc);
2086 if (unlikely(ret)) {
2087 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2088 i, vq->desc + i);
2089 return -EFAULT;
2090 }
2091 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2092 ret = get_indirect(vq, iov, iov_size,
2093 out_num, in_num,
2094 log, log_num, &desc);
2095 if (unlikely(ret < 0)) {
2096 if (ret != -EAGAIN)
2097 vq_err(vq, "Failure detected "
2098 "in indirect descriptor at idx %d\n", i);
2099 return ret;
2100 }
2101 continue;
2102 }
2103
2104 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2105 access = VHOST_ACCESS_WO;
2106 else
2107 access = VHOST_ACCESS_RO;
2108 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2109 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2110 iov_size - iov_count, access);
2111 if (unlikely(ret < 0)) {
2112 if (ret != -EAGAIN)
2113 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2114 ret, i);
2115 return ret;
2116 }
2117 if (access == VHOST_ACCESS_WO) {
2118 /* If this is an input descriptor,
2119 * increment that count. */
2120 *in_num += ret;
2121 if (unlikely(log)) {
2122 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2123 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2124 ++*log_num;
2125 }
2126 } else {
2127 /* If it's an output descriptor, they're all supposed
2128 * to come before any input descriptors. */
2129 if (unlikely(*in_num)) {
2130 vq_err(vq, "Descriptor has out after in: "
2131 "idx %d\n", i);
2132 return -EINVAL;
2133 }
2134 *out_num += ret;
2135 }
2136 } while ((i = next_desc(vq, &desc)) != -1);
2137
2138 /* On success, increment avail index. */
2139 vq->last_avail_idx++;
2140
2141 /* Assume notifications from guest are disabled at this point,
2142 * if they aren't we would need to update avail_event index. */
2143 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2144 return head;
2145 }
2146 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2147
2148 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2149 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2150 {
2151 vq->last_avail_idx -= n;
2152 }
2153 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2154
2155 /* After we've used one of their buffers, we tell them about it. We'll then
2156 * want to notify the guest, using eventfd. */
2157 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2158 {
2159 struct vring_used_elem heads = {
2160 cpu_to_vhost32(vq, head),
2161 cpu_to_vhost32(vq, len)
2162 };
2163
2164 return vhost_add_used_n(vq, &heads, 1);
2165 }
2166 EXPORT_SYMBOL_GPL(vhost_add_used);
2167
2168 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2169 struct vring_used_elem *heads,
2170 unsigned count)
2171 {
2172 struct vring_used_elem __user *used;
2173 u16 old, new;
2174 int start;
2175
2176 start = vq->last_used_idx & (vq->num - 1);
2177 used = vq->used->ring + start;
2178 if (count == 1) {
2179 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2180 vq_err(vq, "Failed to write used id");
2181 return -EFAULT;
2182 }
2183 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2184 vq_err(vq, "Failed to write used len");
2185 return -EFAULT;
2186 }
2187 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2188 vq_err(vq, "Failed to write used");
2189 return -EFAULT;
2190 }
2191 if (unlikely(vq->log_used)) {
2192 /* Make sure data is seen before log. */
2193 smp_wmb();
2194 /* Log used ring entry write. */
2195 log_write(vq->log_base,
2196 vq->log_addr +
2197 ((void __user *)used - (void __user *)vq->used),
2198 count * sizeof *used);
2199 }
2200 old = vq->last_used_idx;
2201 new = (vq->last_used_idx += count);
2202 /* If the driver never bothers to signal in a very long while,
2203 * used index might wrap around. If that happens, invalidate
2204 * signalled_used index we stored. TODO: make sure driver
2205 * signals at least once in 2^16 and remove this. */
2206 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2207 vq->signalled_used_valid = false;
2208 return 0;
2209 }
2210
2211 /* After we've used one of their buffers, we tell them about it. We'll then
2212 * want to notify the guest, using eventfd. */
2213 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2214 unsigned count)
2215 {
2216 int start, n, r;
2217
2218 start = vq->last_used_idx & (vq->num - 1);
2219 n = vq->num - start;
2220 if (n < count) {
2221 r = __vhost_add_used_n(vq, heads, n);
2222 if (r < 0)
2223 return r;
2224 heads += n;
2225 count -= n;
2226 }
2227 r = __vhost_add_used_n(vq, heads, count);
2228
2229 /* Make sure buffer is written before we update index. */
2230 smp_wmb();
2231 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2232 &vq->used->idx)) {
2233 vq_err(vq, "Failed to increment used idx");
2234 return -EFAULT;
2235 }
2236 if (unlikely(vq->log_used)) {
2237 /* Log used index update. */
2238 log_write(vq->log_base,
2239 vq->log_addr + offsetof(struct vring_used, idx),
2240 sizeof vq->used->idx);
2241 if (vq->log_ctx)
2242 eventfd_signal(vq->log_ctx, 1);
2243 }
2244 return r;
2245 }
2246 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2247
2248 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2249 {
2250 __u16 old, new;
2251 __virtio16 event;
2252 bool v;
2253
2254 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2255 unlikely(vq->avail_idx == vq->last_avail_idx))
2256 return true;
2257
2258 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2259 __virtio16 flags;
2260 /* Flush out used index updates. This is paired
2261 * with the barrier that the Guest executes when enabling
2262 * interrupts. */
2263 smp_mb();
2264 if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
2265 vq_err(vq, "Failed to get flags");
2266 return true;
2267 }
2268 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2269 }
2270 old = vq->signalled_used;
2271 v = vq->signalled_used_valid;
2272 new = vq->signalled_used = vq->last_used_idx;
2273 vq->signalled_used_valid = true;
2274
2275 if (unlikely(!v))
2276 return true;
2277
2278 /* We're sure if the following conditions are met, there's no
2279 * need to notify guest:
2280 * 1) cached used event is ahead of new
2281 * 2) old to new updating does not cross cached used event. */
2282 if (vring_need_event(vq->last_used_event, new + vq->num, new) &&
2283 !vring_need_event(vq->last_used_event, new, old))
2284 return false;
2285
2286 /* Flush out used index updates. This is paired
2287 * with the barrier that the Guest executes when enabling
2288 * interrupts. */
2289 smp_mb();
2290
2291 if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
2292 vq_err(vq, "Failed to get used event idx");
2293 return true;
2294 }
2295 vq->last_used_event = vhost16_to_cpu(vq, event);
2296
2297 return vring_need_event(vq->last_used_event, new, old);
2298 }
2299
2300 /* This actually signals the guest, using eventfd. */
2301 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2302 {
2303 /* Signal the Guest tell them we used something up. */
2304 if (vq->call_ctx && vhost_notify(dev, vq))
2305 eventfd_signal(vq->call_ctx, 1);
2306 }
2307 EXPORT_SYMBOL_GPL(vhost_signal);
2308
2309 /* And here's the combo meal deal. Supersize me! */
2310 void vhost_add_used_and_signal(struct vhost_dev *dev,
2311 struct vhost_virtqueue *vq,
2312 unsigned int head, int len)
2313 {
2314 vhost_add_used(vq, head, len);
2315 vhost_signal(dev, vq);
2316 }
2317 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2318
2319 /* multi-buffer version of vhost_add_used_and_signal */
2320 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2321 struct vhost_virtqueue *vq,
2322 struct vring_used_elem *heads, unsigned count)
2323 {
2324 vhost_add_used_n(vq, heads, count);
2325 vhost_signal(dev, vq);
2326 }
2327 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2328
2329 /* return true if we're sure that avaiable ring is empty */
2330 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2331 {
2332 __virtio16 avail_idx;
2333 int r;
2334
2335 if (vq->avail_idx != vq->last_avail_idx)
2336 return false;
2337
2338 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2339 if (unlikely(r))
2340 return false;
2341 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2342
2343 return vq->avail_idx == vq->last_avail_idx;
2344 }
2345 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2346
2347 /* OK, now we need to know about added descriptors. */
2348 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2349 {
2350 __virtio16 avail_idx;
2351 int r;
2352
2353 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2354 return false;
2355 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2356 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2357 r = vhost_update_used_flags(vq);
2358 if (r) {
2359 vq_err(vq, "Failed to enable notification at %p: %d\n",
2360 &vq->used->flags, r);
2361 return false;
2362 }
2363 } else {
2364 r = vhost_update_avail_event(vq, vq->avail_idx);
2365 if (r) {
2366 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2367 vhost_avail_event(vq), r);
2368 return false;
2369 }
2370 }
2371 /* They could have slipped one in as we were doing that: make
2372 * sure it's written, then check again. */
2373 smp_mb();
2374 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2375 if (r) {
2376 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2377 &vq->avail->idx, r);
2378 return false;
2379 }
2380
2381 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2382 }
2383 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2384
2385 /* We don't need to be notified again. */
2386 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2387 {
2388 int r;
2389
2390 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2391 return;
2392 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2393 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2394 r = vhost_update_used_flags(vq);
2395 if (r)
2396 vq_err(vq, "Failed to enable notification at %p: %d\n",
2397 &vq->used->flags, r);
2398 }
2399 }
2400 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2401
2402 /* Create a new message. */
2403 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2404 {
2405 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2406 if (!node)
2407 return NULL;
2408 node->vq = vq;
2409 node->msg.type = type;
2410 return node;
2411 }
2412 EXPORT_SYMBOL_GPL(vhost_new_msg);
2413
2414 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2415 struct vhost_msg_node *node)
2416 {
2417 spin_lock(&dev->iotlb_lock);
2418 list_add_tail(&node->node, head);
2419 spin_unlock(&dev->iotlb_lock);
2420
2421 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
2422 }
2423 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2424
2425 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2426 struct list_head *head)
2427 {
2428 struct vhost_msg_node *node = NULL;
2429
2430 spin_lock(&dev->iotlb_lock);
2431 if (!list_empty(head)) {
2432 node = list_first_entry(head, struct vhost_msg_node,
2433 node);
2434 list_del(&node->node);
2435 }
2436 spin_unlock(&dev->iotlb_lock);
2437
2438 return node;
2439 }
2440 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2441
2442
2443 static int __init vhost_init(void)
2444 {
2445 return 0;
2446 }
2447
2448 static void __exit vhost_exit(void)
2449 {
2450 }
2451
2452 module_init(vhost_init);
2453 module_exit(vhost_exit);
2454
2455 MODULE_VERSION("0.0.1");
2456 MODULE_LICENSE("GPL v2");
2457 MODULE_AUTHOR("Michael S. Tsirkin");
2458 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
Linux with added FPC-III support