xref: /openbmc/linux/drivers/vhost/vhost.c (revision 68198dca)
1 /* Copyright (C) 2009 Red Hat, Inc.
2  * Copyright (C) 2006 Rusty Russell IBM Corporation
3  *
4  * Author: Michael S. Tsirkin <mst@redhat.com>
5  *
6  * Inspiration, some code, and most witty comments come from
7  * Documentation/virtual/lguest/lguest.c, by Rusty Russell
8  *
9  * This work is licensed under the terms of the GNU GPL, version 2.
10  *
11  * Generic code for virtio server in host kernel.
12  */
13 
14 #include <linux/eventfd.h>
15 #include <linux/vhost.h>
16 #include <linux/uio.h>
17 #include <linux/mm.h>
18 #include <linux/mmu_context.h>
19 #include <linux/miscdevice.h>
20 #include <linux/mutex.h>
21 #include <linux/poll.h>
22 #include <linux/file.h>
23 #include <linux/highmem.h>
24 #include <linux/slab.h>
25 #include <linux/vmalloc.h>
26 #include <linux/kthread.h>
27 #include <linux/cgroup.h>
28 #include <linux/module.h>
29 #include <linux/sort.h>
30 #include <linux/sched/mm.h>
31 #include <linux/sched/signal.h>
32 #include <linux/interval_tree_generic.h>
33 
34 #include "vhost.h"
35 
36 static ushort max_mem_regions = 64;
37 module_param(max_mem_regions, ushort, 0444);
38 MODULE_PARM_DESC(max_mem_regions,
39 	"Maximum number of memory regions in memory map. (default: 64)");
40 static int max_iotlb_entries = 2048;
41 module_param(max_iotlb_entries, int, 0444);
42 MODULE_PARM_DESC(max_iotlb_entries,
43 	"Maximum number of iotlb entries. (default: 2048)");
44 
45 enum {
46 	VHOST_MEMORY_F_LOG = 0x1,
47 };
48 
49 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
50 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
51 
52 INTERVAL_TREE_DEFINE(struct vhost_umem_node,
53 		     rb, __u64, __subtree_last,
54 		     START, LAST, static inline, vhost_umem_interval_tree);
55 
56 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
57 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
58 {
59 	vq->user_be = !virtio_legacy_is_little_endian();
60 }
61 
62 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
63 {
64 	vq->user_be = true;
65 }
66 
67 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
68 {
69 	vq->user_be = false;
70 }
71 
72 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
73 {
74 	struct vhost_vring_state s;
75 
76 	if (vq->private_data)
77 		return -EBUSY;
78 
79 	if (copy_from_user(&s, argp, sizeof(s)))
80 		return -EFAULT;
81 
82 	if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
83 	    s.num != VHOST_VRING_BIG_ENDIAN)
84 		return -EINVAL;
85 
86 	if (s.num == VHOST_VRING_BIG_ENDIAN)
87 		vhost_enable_cross_endian_big(vq);
88 	else
89 		vhost_enable_cross_endian_little(vq);
90 
91 	return 0;
92 }
93 
94 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
95 				   int __user *argp)
96 {
97 	struct vhost_vring_state s = {
98 		.index = idx,
99 		.num = vq->user_be
100 	};
101 
102 	if (copy_to_user(argp, &s, sizeof(s)))
103 		return -EFAULT;
104 
105 	return 0;
106 }
107 
108 static void vhost_init_is_le(struct vhost_virtqueue *vq)
109 {
110 	/* Note for legacy virtio: user_be is initialized at reset time
111 	 * according to the host endianness. If userspace does not set an
112 	 * explicit endianness, the default behavior is native endian, as
113 	 * expected by legacy virtio.
114 	 */
115 	vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
116 }
117 #else
118 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
119 {
120 }
121 
122 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
123 {
124 	return -ENOIOCTLCMD;
125 }
126 
127 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
128 				   int __user *argp)
129 {
130 	return -ENOIOCTLCMD;
131 }
132 
133 static void vhost_init_is_le(struct vhost_virtqueue *vq)
134 {
135 	vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
136 		|| virtio_legacy_is_little_endian();
137 }
138 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
139 
140 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
141 {
142 	vhost_init_is_le(vq);
143 }
144 
145 struct vhost_flush_struct {
146 	struct vhost_work work;
147 	struct completion wait_event;
148 };
149 
150 static void vhost_flush_work(struct vhost_work *work)
151 {
152 	struct vhost_flush_struct *s;
153 
154 	s = container_of(work, struct vhost_flush_struct, work);
155 	complete(&s->wait_event);
156 }
157 
158 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
159 			    poll_table *pt)
160 {
161 	struct vhost_poll *poll;
162 
163 	poll = container_of(pt, struct vhost_poll, table);
164 	poll->wqh = wqh;
165 	add_wait_queue(wqh, &poll->wait);
166 }
167 
168 static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
169 			     void *key)
170 {
171 	struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
172 
173 	if (!((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->avail_idx = 0;
312 	vq->last_used_idx = 0;
313 	vq->signalled_used = 0;
314 	vq->signalled_used_valid = false;
315 	vq->used_flags = 0;
316 	vq->log_used = false;
317 	vq->log_addr = -1ull;
318 	vq->private_data = NULL;
319 	vq->acked_features = 0;
320 	vq->log_base = NULL;
321 	vq->error_ctx = NULL;
322 	vq->error = NULL;
323 	vq->kick = NULL;
324 	vq->call_ctx = NULL;
325 	vq->call = NULL;
326 	vq->log_ctx = NULL;
327 	vhost_reset_is_le(vq);
328 	vhost_disable_cross_endian(vq);
329 	vq->busyloop_timeout = 0;
330 	vq->umem = NULL;
331 	vq->iotlb = NULL;
332 	__vhost_vq_meta_reset(vq);
333 }
334 
335 static int vhost_worker(void *data)
336 {
337 	struct vhost_dev *dev = data;
338 	struct vhost_work *work, *work_next;
339 	struct llist_node *node;
340 	mm_segment_t oldfs = get_fs();
341 
342 	set_fs(USER_DS);
343 	use_mm(dev->mm);
344 
345 	for (;;) {
346 		/* mb paired w/ kthread_stop */
347 		set_current_state(TASK_INTERRUPTIBLE);
348 
349 		if (kthread_should_stop()) {
350 			__set_current_state(TASK_RUNNING);
351 			break;
352 		}
353 
354 		node = llist_del_all(&dev->work_list);
355 		if (!node)
356 			schedule();
357 
358 		node = llist_reverse_order(node);
359 		/* make sure flag is seen after deletion */
360 		smp_wmb();
361 		llist_for_each_entry_safe(work, work_next, node, node) {
362 			clear_bit(VHOST_WORK_QUEUED, &work->flags);
363 			__set_current_state(TASK_RUNNING);
364 			work->fn(work);
365 			if (need_resched())
366 				schedule();
367 		}
368 	}
369 	unuse_mm(dev->mm);
370 	set_fs(oldfs);
371 	return 0;
372 }
373 
374 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
375 {
376 	kfree(vq->indirect);
377 	vq->indirect = NULL;
378 	kfree(vq->log);
379 	vq->log = NULL;
380 	kfree(vq->heads);
381 	vq->heads = NULL;
382 }
383 
384 /* Helper to allocate iovec buffers for all vqs. */
385 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
386 {
387 	struct vhost_virtqueue *vq;
388 	int i;
389 
390 	for (i = 0; i < dev->nvqs; ++i) {
391 		vq = dev->vqs[i];
392 		vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
393 				       GFP_KERNEL);
394 		vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
395 		vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
396 		if (!vq->indirect || !vq->log || !vq->heads)
397 			goto err_nomem;
398 	}
399 	return 0;
400 
401 err_nomem:
402 	for (; i >= 0; --i)
403 		vhost_vq_free_iovecs(dev->vqs[i]);
404 	return -ENOMEM;
405 }
406 
407 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
408 {
409 	int i;
410 
411 	for (i = 0; i < dev->nvqs; ++i)
412 		vhost_vq_free_iovecs(dev->vqs[i]);
413 }
414 
415 void vhost_dev_init(struct vhost_dev *dev,
416 		    struct vhost_virtqueue **vqs, int nvqs)
417 {
418 	struct vhost_virtqueue *vq;
419 	int i;
420 
421 	dev->vqs = vqs;
422 	dev->nvqs = nvqs;
423 	mutex_init(&dev->mutex);
424 	dev->log_ctx = NULL;
425 	dev->log_file = NULL;
426 	dev->umem = NULL;
427 	dev->iotlb = NULL;
428 	dev->mm = NULL;
429 	dev->worker = NULL;
430 	init_llist_head(&dev->work_list);
431 	init_waitqueue_head(&dev->wait);
432 	INIT_LIST_HEAD(&dev->read_list);
433 	INIT_LIST_HEAD(&dev->pending_list);
434 	spin_lock_init(&dev->iotlb_lock);
435 
436 
437 	for (i = 0; i < dev->nvqs; ++i) {
438 		vq = dev->vqs[i];
439 		vq->log = NULL;
440 		vq->indirect = NULL;
441 		vq->heads = NULL;
442 		vq->dev = dev;
443 		mutex_init(&vq->mutex);
444 		vhost_vq_reset(dev, vq);
445 		if (vq->handle_kick)
446 			vhost_poll_init(&vq->poll, vq->handle_kick,
447 					POLLIN, dev);
448 	}
449 }
450 EXPORT_SYMBOL_GPL(vhost_dev_init);
451 
452 /* Caller should have device mutex */
453 long vhost_dev_check_owner(struct vhost_dev *dev)
454 {
455 	/* Are you the owner? If not, I don't think you mean to do that */
456 	return dev->mm == current->mm ? 0 : -EPERM;
457 }
458 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
459 
460 struct vhost_attach_cgroups_struct {
461 	struct vhost_work work;
462 	struct task_struct *owner;
463 	int ret;
464 };
465 
466 static void vhost_attach_cgroups_work(struct vhost_work *work)
467 {
468 	struct vhost_attach_cgroups_struct *s;
469 
470 	s = container_of(work, struct vhost_attach_cgroups_struct, work);
471 	s->ret = cgroup_attach_task_all(s->owner, current);
472 }
473 
474 static int vhost_attach_cgroups(struct vhost_dev *dev)
475 {
476 	struct vhost_attach_cgroups_struct attach;
477 
478 	attach.owner = current;
479 	vhost_work_init(&attach.work, vhost_attach_cgroups_work);
480 	vhost_work_queue(dev, &attach.work);
481 	vhost_work_flush(dev, &attach.work);
482 	return attach.ret;
483 }
484 
485 /* Caller should have device mutex */
486 bool vhost_dev_has_owner(struct vhost_dev *dev)
487 {
488 	return dev->mm;
489 }
490 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
491 
492 /* Caller should have device mutex */
493 long vhost_dev_set_owner(struct vhost_dev *dev)
494 {
495 	struct task_struct *worker;
496 	int err;
497 
498 	/* Is there an owner already? */
499 	if (vhost_dev_has_owner(dev)) {
500 		err = -EBUSY;
501 		goto err_mm;
502 	}
503 
504 	/* No owner, become one */
505 	dev->mm = get_task_mm(current);
506 	worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
507 	if (IS_ERR(worker)) {
508 		err = PTR_ERR(worker);
509 		goto err_worker;
510 	}
511 
512 	dev->worker = worker;
513 	wake_up_process(worker);	/* avoid contributing to loadavg */
514 
515 	err = vhost_attach_cgroups(dev);
516 	if (err)
517 		goto err_cgroup;
518 
519 	err = vhost_dev_alloc_iovecs(dev);
520 	if (err)
521 		goto err_cgroup;
522 
523 	return 0;
524 err_cgroup:
525 	kthread_stop(worker);
526 	dev->worker = NULL;
527 err_worker:
528 	if (dev->mm)
529 		mmput(dev->mm);
530 	dev->mm = NULL;
531 err_mm:
532 	return err;
533 }
534 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
535 
536 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
537 {
538 	return kvzalloc(sizeof(struct vhost_umem), GFP_KERNEL);
539 }
540 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
541 
542 /* Caller should have device mutex */
543 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
544 {
545 	int i;
546 
547 	vhost_dev_cleanup(dev, true);
548 
549 	/* Restore memory to default empty mapping. */
550 	INIT_LIST_HEAD(&umem->umem_list);
551 	dev->umem = umem;
552 	/* We don't need VQ locks below since vhost_dev_cleanup makes sure
553 	 * VQs aren't running.
554 	 */
555 	for (i = 0; i < dev->nvqs; ++i)
556 		dev->vqs[i]->umem = umem;
557 }
558 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
559 
560 void vhost_dev_stop(struct vhost_dev *dev)
561 {
562 	int i;
563 
564 	for (i = 0; i < dev->nvqs; ++i) {
565 		if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
566 			vhost_poll_stop(&dev->vqs[i]->poll);
567 			vhost_poll_flush(&dev->vqs[i]->poll);
568 		}
569 	}
570 }
571 EXPORT_SYMBOL_GPL(vhost_dev_stop);
572 
573 static void vhost_umem_free(struct vhost_umem *umem,
574 			    struct vhost_umem_node *node)
575 {
576 	vhost_umem_interval_tree_remove(node, &umem->umem_tree);
577 	list_del(&node->link);
578 	kfree(node);
579 	umem->numem--;
580 }
581 
582 static void vhost_umem_clean(struct vhost_umem *umem)
583 {
584 	struct vhost_umem_node *node, *tmp;
585 
586 	if (!umem)
587 		return;
588 
589 	list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
590 		vhost_umem_free(umem, node);
591 
592 	kvfree(umem);
593 }
594 
595 static void vhost_clear_msg(struct vhost_dev *dev)
596 {
597 	struct vhost_msg_node *node, *n;
598 
599 	spin_lock(&dev->iotlb_lock);
600 
601 	list_for_each_entry_safe(node, n, &dev->read_list, node) {
602 		list_del(&node->node);
603 		kfree(node);
604 	}
605 
606 	list_for_each_entry_safe(node, n, &dev->pending_list, node) {
607 		list_del(&node->node);
608 		kfree(node);
609 	}
610 
611 	spin_unlock(&dev->iotlb_lock);
612 }
613 
614 /* Caller should have device mutex if and only if locked is set */
615 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
616 {
617 	int i;
618 
619 	for (i = 0; i < dev->nvqs; ++i) {
620 		if (dev->vqs[i]->error_ctx)
621 			eventfd_ctx_put(dev->vqs[i]->error_ctx);
622 		if (dev->vqs[i]->error)
623 			fput(dev->vqs[i]->error);
624 		if (dev->vqs[i]->kick)
625 			fput(dev->vqs[i]->kick);
626 		if (dev->vqs[i]->call_ctx)
627 			eventfd_ctx_put(dev->vqs[i]->call_ctx);
628 		if (dev->vqs[i]->call)
629 			fput(dev->vqs[i]->call);
630 		vhost_vq_reset(dev, dev->vqs[i]);
631 	}
632 	vhost_dev_free_iovecs(dev);
633 	if (dev->log_ctx)
634 		eventfd_ctx_put(dev->log_ctx);
635 	dev->log_ctx = NULL;
636 	if (dev->log_file)
637 		fput(dev->log_file);
638 	dev->log_file = NULL;
639 	/* No one will access memory at this point */
640 	vhost_umem_clean(dev->umem);
641 	dev->umem = NULL;
642 	vhost_umem_clean(dev->iotlb);
643 	dev->iotlb = NULL;
644 	vhost_clear_msg(dev);
645 	wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
646 	WARN_ON(!llist_empty(&dev->work_list));
647 	if (dev->worker) {
648 		kthread_stop(dev->worker);
649 		dev->worker = NULL;
650 	}
651 	if (dev->mm)
652 		mmput(dev->mm);
653 	dev->mm = NULL;
654 }
655 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
656 
657 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
658 {
659 	u64 a = addr / VHOST_PAGE_SIZE / 8;
660 
661 	/* Make sure 64 bit math will not overflow. */
662 	if (a > ULONG_MAX - (unsigned long)log_base ||
663 	    a + (unsigned long)log_base > ULONG_MAX)
664 		return 0;
665 
666 	return access_ok(VERIFY_WRITE, log_base + a,
667 			 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
668 }
669 
670 static bool vhost_overflow(u64 uaddr, u64 size)
671 {
672 	/* Make sure 64 bit math will not overflow. */
673 	return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
674 }
675 
676 /* Caller should have vq mutex and device mutex. */
677 static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
678 			       int log_all)
679 {
680 	struct vhost_umem_node *node;
681 
682 	if (!umem)
683 		return 0;
684 
685 	list_for_each_entry(node, &umem->umem_list, link) {
686 		unsigned long a = node->userspace_addr;
687 
688 		if (vhost_overflow(node->userspace_addr, node->size))
689 			return 0;
690 
691 
692 		if (!access_ok(VERIFY_WRITE, (void __user *)a,
693 				    node->size))
694 			return 0;
695 		else if (log_all && !log_access_ok(log_base,
696 						   node->start,
697 						   node->size))
698 			return 0;
699 	}
700 	return 1;
701 }
702 
703 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
704 					       u64 addr, unsigned int size,
705 					       int type)
706 {
707 	const struct vhost_umem_node *node = vq->meta_iotlb[type];
708 
709 	if (!node)
710 		return NULL;
711 
712 	return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
713 }
714 
715 /* Can we switch to this memory table? */
716 /* Caller should have device mutex but not vq mutex */
717 static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
718 			    int log_all)
719 {
720 	int i;
721 
722 	for (i = 0; i < d->nvqs; ++i) {
723 		int ok;
724 		bool log;
725 
726 		mutex_lock(&d->vqs[i]->mutex);
727 		log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
728 		/* If ring is inactive, will check when it's enabled. */
729 		if (d->vqs[i]->private_data)
730 			ok = vq_memory_access_ok(d->vqs[i]->log_base,
731 						 umem, log);
732 		else
733 			ok = 1;
734 		mutex_unlock(&d->vqs[i]->mutex);
735 		if (!ok)
736 			return 0;
737 	}
738 	return 1;
739 }
740 
741 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
742 			  struct iovec iov[], int iov_size, int access);
743 
744 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
745 			      const void *from, unsigned size)
746 {
747 	int ret;
748 
749 	if (!vq->iotlb)
750 		return __copy_to_user(to, from, size);
751 	else {
752 		/* This function should be called after iotlb
753 		 * prefetch, which means we're sure that all vq
754 		 * could be access through iotlb. So -EAGAIN should
755 		 * not happen in this case.
756 		 */
757 		struct iov_iter t;
758 		void __user *uaddr = vhost_vq_meta_fetch(vq,
759 				     (u64)(uintptr_t)to, size,
760 				     VHOST_ADDR_DESC);
761 
762 		if (uaddr)
763 			return __copy_to_user(uaddr, from, size);
764 
765 		ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
766 				     ARRAY_SIZE(vq->iotlb_iov),
767 				     VHOST_ACCESS_WO);
768 		if (ret < 0)
769 			goto out;
770 		iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
771 		ret = copy_to_iter(from, size, &t);
772 		if (ret == size)
773 			ret = 0;
774 	}
775 out:
776 	return ret;
777 }
778 
779 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
780 				void __user *from, unsigned size)
781 {
782 	int ret;
783 
784 	if (!vq->iotlb)
785 		return __copy_from_user(to, from, size);
786 	else {
787 		/* This function should be called after iotlb
788 		 * prefetch, which means we're sure that vq
789 		 * could be access through iotlb. So -EAGAIN should
790 		 * not happen in this case.
791 		 */
792 		void __user *uaddr = vhost_vq_meta_fetch(vq,
793 				     (u64)(uintptr_t)from, size,
794 				     VHOST_ADDR_DESC);
795 		struct iov_iter f;
796 
797 		if (uaddr)
798 			return __copy_from_user(to, uaddr, size);
799 
800 		ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
801 				     ARRAY_SIZE(vq->iotlb_iov),
802 				     VHOST_ACCESS_RO);
803 		if (ret < 0) {
804 			vq_err(vq, "IOTLB translation failure: uaddr "
805 			       "%p size 0x%llx\n", from,
806 			       (unsigned long long) size);
807 			goto out;
808 		}
809 		iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
810 		ret = copy_from_iter(to, size, &f);
811 		if (ret == size)
812 			ret = 0;
813 	}
814 
815 out:
816 	return ret;
817 }
818 
819 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
820 					  void __user *addr, unsigned int size,
821 					  int type)
822 {
823 	int ret;
824 
825 	ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
826 			     ARRAY_SIZE(vq->iotlb_iov),
827 			     VHOST_ACCESS_RO);
828 	if (ret < 0) {
829 		vq_err(vq, "IOTLB translation failure: uaddr "
830 			"%p size 0x%llx\n", addr,
831 			(unsigned long long) size);
832 		return NULL;
833 	}
834 
835 	if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
836 		vq_err(vq, "Non atomic userspace memory access: uaddr "
837 			"%p size 0x%llx\n", addr,
838 			(unsigned long long) size);
839 		return NULL;
840 	}
841 
842 	return vq->iotlb_iov[0].iov_base;
843 }
844 
845 /* This function should be called after iotlb
846  * prefetch, which means we're sure that vq
847  * could be access through iotlb. So -EAGAIN should
848  * not happen in this case.
849  */
850 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
851 					    void *addr, unsigned int size,
852 					    int type)
853 {
854 	void __user *uaddr = vhost_vq_meta_fetch(vq,
855 			     (u64)(uintptr_t)addr, size, type);
856 	if (uaddr)
857 		return uaddr;
858 
859 	return __vhost_get_user_slow(vq, addr, size, type);
860 }
861 
862 #define vhost_put_user(vq, x, ptr)		\
863 ({ \
864 	int ret = -EFAULT; \
865 	if (!vq->iotlb) { \
866 		ret = __put_user(x, ptr); \
867 	} else { \
868 		__typeof__(ptr) to = \
869 			(__typeof__(ptr)) __vhost_get_user(vq, ptr,	\
870 					  sizeof(*ptr), VHOST_ADDR_USED); \
871 		if (to != NULL) \
872 			ret = __put_user(x, to); \
873 		else \
874 			ret = -EFAULT;	\
875 	} \
876 	ret; \
877 })
878 
879 #define vhost_get_user(vq, x, ptr, type)		\
880 ({ \
881 	int ret; \
882 	if (!vq->iotlb) { \
883 		ret = __get_user(x, ptr); \
884 	} else { \
885 		__typeof__(ptr) from = \
886 			(__typeof__(ptr)) __vhost_get_user(vq, ptr, \
887 							   sizeof(*ptr), \
888 							   type); \
889 		if (from != NULL) \
890 			ret = __get_user(x, from); \
891 		else \
892 			ret = -EFAULT; \
893 	} \
894 	ret; \
895 })
896 
897 #define vhost_get_avail(vq, x, ptr) \
898 	vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
899 
900 #define vhost_get_used(vq, x, ptr) \
901 	vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
902 
903 static void vhost_dev_lock_vqs(struct vhost_dev *d)
904 {
905 	int i = 0;
906 	for (i = 0; i < d->nvqs; ++i)
907 		mutex_lock(&d->vqs[i]->mutex);
908 }
909 
910 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
911 {
912 	int i = 0;
913 	for (i = 0; i < d->nvqs; ++i)
914 		mutex_unlock(&d->vqs[i]->mutex);
915 }
916 
917 static int vhost_new_umem_range(struct vhost_umem *umem,
918 				u64 start, u64 size, u64 end,
919 				u64 userspace_addr, int perm)
920 {
921 	struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
922 
923 	if (!node)
924 		return -ENOMEM;
925 
926 	if (umem->numem == max_iotlb_entries) {
927 		tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
928 		vhost_umem_free(umem, tmp);
929 	}
930 
931 	node->start = start;
932 	node->size = size;
933 	node->last = end;
934 	node->userspace_addr = userspace_addr;
935 	node->perm = perm;
936 	INIT_LIST_HEAD(&node->link);
937 	list_add_tail(&node->link, &umem->umem_list);
938 	vhost_umem_interval_tree_insert(node, &umem->umem_tree);
939 	umem->numem++;
940 
941 	return 0;
942 }
943 
944 static void vhost_del_umem_range(struct vhost_umem *umem,
945 				 u64 start, u64 end)
946 {
947 	struct vhost_umem_node *node;
948 
949 	while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
950 							   start, end)))
951 		vhost_umem_free(umem, node);
952 }
953 
954 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
955 				  struct vhost_iotlb_msg *msg)
956 {
957 	struct vhost_msg_node *node, *n;
958 
959 	spin_lock(&d->iotlb_lock);
960 
961 	list_for_each_entry_safe(node, n, &d->pending_list, node) {
962 		struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
963 		if (msg->iova <= vq_msg->iova &&
964 		    msg->iova + msg->size - 1 > vq_msg->iova &&
965 		    vq_msg->type == VHOST_IOTLB_MISS) {
966 			vhost_poll_queue(&node->vq->poll);
967 			list_del(&node->node);
968 			kfree(node);
969 		}
970 	}
971 
972 	spin_unlock(&d->iotlb_lock);
973 }
974 
975 static int umem_access_ok(u64 uaddr, u64 size, int access)
976 {
977 	unsigned long a = uaddr;
978 
979 	/* Make sure 64 bit math will not overflow. */
980 	if (vhost_overflow(uaddr, size))
981 		return -EFAULT;
982 
983 	if ((access & VHOST_ACCESS_RO) &&
984 	    !access_ok(VERIFY_READ, (void __user *)a, size))
985 		return -EFAULT;
986 	if ((access & VHOST_ACCESS_WO) &&
987 	    !access_ok(VERIFY_WRITE, (void __user *)a, size))
988 		return -EFAULT;
989 	return 0;
990 }
991 
992 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
993 				   struct vhost_iotlb_msg *msg)
994 {
995 	int ret = 0;
996 
997 	vhost_dev_lock_vqs(dev);
998 	switch (msg->type) {
999 	case VHOST_IOTLB_UPDATE:
1000 		if (!dev->iotlb) {
1001 			ret = -EFAULT;
1002 			break;
1003 		}
1004 		if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1005 			ret = -EFAULT;
1006 			break;
1007 		}
1008 		vhost_vq_meta_reset(dev);
1009 		if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
1010 					 msg->iova + msg->size - 1,
1011 					 msg->uaddr, msg->perm)) {
1012 			ret = -ENOMEM;
1013 			break;
1014 		}
1015 		vhost_iotlb_notify_vq(dev, msg);
1016 		break;
1017 	case VHOST_IOTLB_INVALIDATE:
1018 		vhost_vq_meta_reset(dev);
1019 		vhost_del_umem_range(dev->iotlb, msg->iova,
1020 				     msg->iova + msg->size - 1);
1021 		break;
1022 	default:
1023 		ret = -EINVAL;
1024 		break;
1025 	}
1026 
1027 	vhost_dev_unlock_vqs(dev);
1028 	return ret;
1029 }
1030 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1031 			     struct iov_iter *from)
1032 {
1033 	struct vhost_msg_node node;
1034 	unsigned size = sizeof(struct vhost_msg);
1035 	size_t ret;
1036 	int err;
1037 
1038 	if (iov_iter_count(from) < size)
1039 		return 0;
1040 	ret = copy_from_iter(&node.msg, size, from);
1041 	if (ret != size)
1042 		goto done;
1043 
1044 	switch (node.msg.type) {
1045 	case VHOST_IOTLB_MSG:
1046 		err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
1047 		if (err)
1048 			ret = err;
1049 		break;
1050 	default:
1051 		ret = -EINVAL;
1052 		break;
1053 	}
1054 
1055 done:
1056 	return ret;
1057 }
1058 EXPORT_SYMBOL(vhost_chr_write_iter);
1059 
1060 unsigned int vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1061 			    poll_table *wait)
1062 {
1063 	unsigned int mask = 0;
1064 
1065 	poll_wait(file, &dev->wait, wait);
1066 
1067 	if (!list_empty(&dev->read_list))
1068 		mask |= POLLIN | POLLRDNORM;
1069 
1070 	return mask;
1071 }
1072 EXPORT_SYMBOL(vhost_chr_poll);
1073 
1074 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1075 			    int noblock)
1076 {
1077 	DEFINE_WAIT(wait);
1078 	struct vhost_msg_node *node;
1079 	ssize_t ret = 0;
1080 	unsigned size = sizeof(struct vhost_msg);
1081 
1082 	if (iov_iter_count(to) < size)
1083 		return 0;
1084 
1085 	while (1) {
1086 		if (!noblock)
1087 			prepare_to_wait(&dev->wait, &wait,
1088 					TASK_INTERRUPTIBLE);
1089 
1090 		node = vhost_dequeue_msg(dev, &dev->read_list);
1091 		if (node)
1092 			break;
1093 		if (noblock) {
1094 			ret = -EAGAIN;
1095 			break;
1096 		}
1097 		if (signal_pending(current)) {
1098 			ret = -ERESTARTSYS;
1099 			break;
1100 		}
1101 		if (!dev->iotlb) {
1102 			ret = -EBADFD;
1103 			break;
1104 		}
1105 
1106 		schedule();
1107 	}
1108 
1109 	if (!noblock)
1110 		finish_wait(&dev->wait, &wait);
1111 
1112 	if (node) {
1113 		ret = copy_to_iter(&node->msg, size, to);
1114 
1115 		if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {
1116 			kfree(node);
1117 			return ret;
1118 		}
1119 
1120 		vhost_enqueue_msg(dev, &dev->pending_list, node);
1121 	}
1122 
1123 	return ret;
1124 }
1125 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1126 
1127 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1128 {
1129 	struct vhost_dev *dev = vq->dev;
1130 	struct vhost_msg_node *node;
1131 	struct vhost_iotlb_msg *msg;
1132 
1133 	node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
1134 	if (!node)
1135 		return -ENOMEM;
1136 
1137 	msg = &node->msg.iotlb;
1138 	msg->type = VHOST_IOTLB_MISS;
1139 	msg->iova = iova;
1140 	msg->perm = access;
1141 
1142 	vhost_enqueue_msg(dev, &dev->read_list, node);
1143 
1144 	return 0;
1145 }
1146 
1147 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1148 			struct vring_desc __user *desc,
1149 			struct vring_avail __user *avail,
1150 			struct vring_used __user *used)
1151 
1152 {
1153 	size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1154 
1155 	return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
1156 	       access_ok(VERIFY_READ, avail,
1157 			 sizeof *avail + num * sizeof *avail->ring + s) &&
1158 	       access_ok(VERIFY_WRITE, used,
1159 			sizeof *used + num * sizeof *used->ring + s);
1160 }
1161 
1162 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1163 				 const struct vhost_umem_node *node,
1164 				 int type)
1165 {
1166 	int access = (type == VHOST_ADDR_USED) ?
1167 		     VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1168 
1169 	if (likely(node->perm & access))
1170 		vq->meta_iotlb[type] = node;
1171 }
1172 
1173 static int iotlb_access_ok(struct vhost_virtqueue *vq,
1174 			   int access, u64 addr, u64 len, int type)
1175 {
1176 	const struct vhost_umem_node *node;
1177 	struct vhost_umem *umem = vq->iotlb;
1178 	u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1179 
1180 	if (vhost_vq_meta_fetch(vq, addr, len, type))
1181 		return true;
1182 
1183 	while (len > s) {
1184 		node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1185 							   addr,
1186 							   last);
1187 		if (node == NULL || node->start > addr) {
1188 			vhost_iotlb_miss(vq, addr, access);
1189 			return false;
1190 		} else if (!(node->perm & access)) {
1191 			/* Report the possible access violation by
1192 			 * request another translation from userspace.
1193 			 */
1194 			return false;
1195 		}
1196 
1197 		size = node->size - addr + node->start;
1198 
1199 		if (orig_addr == addr && size >= len)
1200 			vhost_vq_meta_update(vq, node, type);
1201 
1202 		s += size;
1203 		addr += size;
1204 	}
1205 
1206 	return true;
1207 }
1208 
1209 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1210 {
1211 	size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1212 	unsigned int num = vq->num;
1213 
1214 	if (!vq->iotlb)
1215 		return 1;
1216 
1217 	return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1218 			       num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
1219 	       iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1220 			       sizeof *vq->avail +
1221 			       num * sizeof(*vq->avail->ring) + s,
1222 			       VHOST_ADDR_AVAIL) &&
1223 	       iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1224 			       sizeof *vq->used +
1225 			       num * sizeof(*vq->used->ring) + s,
1226 			       VHOST_ADDR_USED);
1227 }
1228 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1229 
1230 /* Can we log writes? */
1231 /* Caller should have device mutex but not vq mutex */
1232 int vhost_log_access_ok(struct vhost_dev *dev)
1233 {
1234 	return memory_access_ok(dev, dev->umem, 1);
1235 }
1236 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1237 
1238 /* Verify access for write logging. */
1239 /* Caller should have vq mutex and device mutex */
1240 static int vq_log_access_ok(struct vhost_virtqueue *vq,
1241 			    void __user *log_base)
1242 {
1243 	size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1244 
1245 	return vq_memory_access_ok(log_base, vq->umem,
1246 				   vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1247 		(!vq->log_used || log_access_ok(log_base, vq->log_addr,
1248 					sizeof *vq->used +
1249 					vq->num * sizeof *vq->used->ring + s));
1250 }
1251 
1252 /* Can we start vq? */
1253 /* Caller should have vq mutex and device mutex */
1254 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
1255 {
1256 	if (vq->iotlb) {
1257 		/* When device IOTLB was used, the access validation
1258 		 * will be validated during prefetching.
1259 		 */
1260 		return 1;
1261 	}
1262 	return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
1263 		vq_log_access_ok(vq, vq->log_base);
1264 }
1265 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1266 
1267 static struct vhost_umem *vhost_umem_alloc(void)
1268 {
1269 	struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1270 
1271 	if (!umem)
1272 		return NULL;
1273 
1274 	umem->umem_tree = RB_ROOT_CACHED;
1275 	umem->numem = 0;
1276 	INIT_LIST_HEAD(&umem->umem_list);
1277 
1278 	return umem;
1279 }
1280 
1281 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1282 {
1283 	struct vhost_memory mem, *newmem;
1284 	struct vhost_memory_region *region;
1285 	struct vhost_umem *newumem, *oldumem;
1286 	unsigned long size = offsetof(struct vhost_memory, regions);
1287 	int i;
1288 
1289 	if (copy_from_user(&mem, m, size))
1290 		return -EFAULT;
1291 	if (mem.padding)
1292 		return -EOPNOTSUPP;
1293 	if (mem.nregions > max_mem_regions)
1294 		return -E2BIG;
1295 	newmem = kvzalloc(size + mem.nregions * sizeof(*m->regions), GFP_KERNEL);
1296 	if (!newmem)
1297 		return -ENOMEM;
1298 
1299 	memcpy(newmem, &mem, size);
1300 	if (copy_from_user(newmem->regions, m->regions,
1301 			   mem.nregions * sizeof *m->regions)) {
1302 		kvfree(newmem);
1303 		return -EFAULT;
1304 	}
1305 
1306 	newumem = vhost_umem_alloc();
1307 	if (!newumem) {
1308 		kvfree(newmem);
1309 		return -ENOMEM;
1310 	}
1311 
1312 	for (region = newmem->regions;
1313 	     region < newmem->regions + mem.nregions;
1314 	     region++) {
1315 		if (vhost_new_umem_range(newumem,
1316 					 region->guest_phys_addr,
1317 					 region->memory_size,
1318 					 region->guest_phys_addr +
1319 					 region->memory_size - 1,
1320 					 region->userspace_addr,
1321 					 VHOST_ACCESS_RW))
1322 			goto err;
1323 	}
1324 
1325 	if (!memory_access_ok(d, newumem, 0))
1326 		goto err;
1327 
1328 	oldumem = d->umem;
1329 	d->umem = newumem;
1330 
1331 	/* All memory accesses are done under some VQ mutex. */
1332 	for (i = 0; i < d->nvqs; ++i) {
1333 		mutex_lock(&d->vqs[i]->mutex);
1334 		d->vqs[i]->umem = newumem;
1335 		mutex_unlock(&d->vqs[i]->mutex);
1336 	}
1337 
1338 	kvfree(newmem);
1339 	vhost_umem_clean(oldumem);
1340 	return 0;
1341 
1342 err:
1343 	vhost_umem_clean(newumem);
1344 	kvfree(newmem);
1345 	return -EFAULT;
1346 }
1347 
1348 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
1349 {
1350 	struct file *eventfp, *filep = NULL;
1351 	bool pollstart = false, pollstop = false;
1352 	struct eventfd_ctx *ctx = NULL;
1353 	u32 __user *idxp = argp;
1354 	struct vhost_virtqueue *vq;
1355 	struct vhost_vring_state s;
1356 	struct vhost_vring_file f;
1357 	struct vhost_vring_addr a;
1358 	u32 idx;
1359 	long r;
1360 
1361 	r = get_user(idx, idxp);
1362 	if (r < 0)
1363 		return r;
1364 	if (idx >= d->nvqs)
1365 		return -ENOBUFS;
1366 
1367 	vq = d->vqs[idx];
1368 
1369 	mutex_lock(&vq->mutex);
1370 
1371 	switch (ioctl) {
1372 	case VHOST_SET_VRING_NUM:
1373 		/* Resizing ring with an active backend?
1374 		 * You don't want to do that. */
1375 		if (vq->private_data) {
1376 			r = -EBUSY;
1377 			break;
1378 		}
1379 		if (copy_from_user(&s, argp, sizeof s)) {
1380 			r = -EFAULT;
1381 			break;
1382 		}
1383 		if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1384 			r = -EINVAL;
1385 			break;
1386 		}
1387 		vq->num = s.num;
1388 		break;
1389 	case VHOST_SET_VRING_BASE:
1390 		/* Moving base with an active backend?
1391 		 * You don't want to do that. */
1392 		if (vq->private_data) {
1393 			r = -EBUSY;
1394 			break;
1395 		}
1396 		if (copy_from_user(&s, argp, sizeof s)) {
1397 			r = -EFAULT;
1398 			break;
1399 		}
1400 		if (s.num > 0xffff) {
1401 			r = -EINVAL;
1402 			break;
1403 		}
1404 		vq->last_avail_idx = s.num;
1405 		/* Forget the cached index value. */
1406 		vq->avail_idx = vq->last_avail_idx;
1407 		break;
1408 	case VHOST_GET_VRING_BASE:
1409 		s.index = idx;
1410 		s.num = vq->last_avail_idx;
1411 		if (copy_to_user(argp, &s, sizeof s))
1412 			r = -EFAULT;
1413 		break;
1414 	case VHOST_SET_VRING_ADDR:
1415 		if (copy_from_user(&a, argp, sizeof a)) {
1416 			r = -EFAULT;
1417 			break;
1418 		}
1419 		if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1420 			r = -EOPNOTSUPP;
1421 			break;
1422 		}
1423 		/* For 32bit, verify that the top 32bits of the user
1424 		   data are set to zero. */
1425 		if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1426 		    (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1427 		    (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1428 			r = -EFAULT;
1429 			break;
1430 		}
1431 
1432 		/* Make sure it's safe to cast pointers to vring types. */
1433 		BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1434 		BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1435 		if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1436 		    (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1437 		    (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1438 			r = -EINVAL;
1439 			break;
1440 		}
1441 
1442 		/* We only verify access here if backend is configured.
1443 		 * If it is not, we don't as size might not have been setup.
1444 		 * We will verify when backend is configured. */
1445 		if (vq->private_data) {
1446 			if (!vq_access_ok(vq, vq->num,
1447 				(void __user *)(unsigned long)a.desc_user_addr,
1448 				(void __user *)(unsigned long)a.avail_user_addr,
1449 				(void __user *)(unsigned long)a.used_user_addr)) {
1450 				r = -EINVAL;
1451 				break;
1452 			}
1453 
1454 			/* Also validate log access for used ring if enabled. */
1455 			if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1456 			    !log_access_ok(vq->log_base, a.log_guest_addr,
1457 					   sizeof *vq->used +
1458 					   vq->num * sizeof *vq->used->ring)) {
1459 				r = -EINVAL;
1460 				break;
1461 			}
1462 		}
1463 
1464 		vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1465 		vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1466 		vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1467 		vq->log_addr = a.log_guest_addr;
1468 		vq->used = (void __user *)(unsigned long)a.used_user_addr;
1469 		break;
1470 	case VHOST_SET_VRING_KICK:
1471 		if (copy_from_user(&f, argp, sizeof f)) {
1472 			r = -EFAULT;
1473 			break;
1474 		}
1475 		eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1476 		if (IS_ERR(eventfp)) {
1477 			r = PTR_ERR(eventfp);
1478 			break;
1479 		}
1480 		if (eventfp != vq->kick) {
1481 			pollstop = (filep = vq->kick) != NULL;
1482 			pollstart = (vq->kick = eventfp) != NULL;
1483 		} else
1484 			filep = eventfp;
1485 		break;
1486 	case VHOST_SET_VRING_CALL:
1487 		if (copy_from_user(&f, argp, sizeof f)) {
1488 			r = -EFAULT;
1489 			break;
1490 		}
1491 		eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1492 		if (IS_ERR(eventfp)) {
1493 			r = PTR_ERR(eventfp);
1494 			break;
1495 		}
1496 		if (eventfp != vq->call) {
1497 			filep = vq->call;
1498 			ctx = vq->call_ctx;
1499 			vq->call = eventfp;
1500 			vq->call_ctx = eventfp ?
1501 				eventfd_ctx_fileget(eventfp) : NULL;
1502 		} else
1503 			filep = eventfp;
1504 		break;
1505 	case VHOST_SET_VRING_ERR:
1506 		if (copy_from_user(&f, argp, sizeof f)) {
1507 			r = -EFAULT;
1508 			break;
1509 		}
1510 		eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1511 		if (IS_ERR(eventfp)) {
1512 			r = PTR_ERR(eventfp);
1513 			break;
1514 		}
1515 		if (eventfp != vq->error) {
1516 			filep = vq->error;
1517 			vq->error = eventfp;
1518 			ctx = vq->error_ctx;
1519 			vq->error_ctx = eventfp ?
1520 				eventfd_ctx_fileget(eventfp) : NULL;
1521 		} else
1522 			filep = eventfp;
1523 		break;
1524 	case VHOST_SET_VRING_ENDIAN:
1525 		r = vhost_set_vring_endian(vq, argp);
1526 		break;
1527 	case VHOST_GET_VRING_ENDIAN:
1528 		r = vhost_get_vring_endian(vq, idx, argp);
1529 		break;
1530 	case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1531 		if (copy_from_user(&s, argp, sizeof(s))) {
1532 			r = -EFAULT;
1533 			break;
1534 		}
1535 		vq->busyloop_timeout = s.num;
1536 		break;
1537 	case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1538 		s.index = idx;
1539 		s.num = vq->busyloop_timeout;
1540 		if (copy_to_user(argp, &s, sizeof(s)))
1541 			r = -EFAULT;
1542 		break;
1543 	default:
1544 		r = -ENOIOCTLCMD;
1545 	}
1546 
1547 	if (pollstop && vq->handle_kick)
1548 		vhost_poll_stop(&vq->poll);
1549 
1550 	if (ctx)
1551 		eventfd_ctx_put(ctx);
1552 	if (filep)
1553 		fput(filep);
1554 
1555 	if (pollstart && vq->handle_kick)
1556 		r = vhost_poll_start(&vq->poll, vq->kick);
1557 
1558 	mutex_unlock(&vq->mutex);
1559 
1560 	if (pollstop && vq->handle_kick)
1561 		vhost_poll_flush(&vq->poll);
1562 	return r;
1563 }
1564 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1565 
1566 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1567 {
1568 	struct vhost_umem *niotlb, *oiotlb;
1569 	int i;
1570 
1571 	niotlb = vhost_umem_alloc();
1572 	if (!niotlb)
1573 		return -ENOMEM;
1574 
1575 	oiotlb = d->iotlb;
1576 	d->iotlb = niotlb;
1577 
1578 	for (i = 0; i < d->nvqs; ++i) {
1579 		mutex_lock(&d->vqs[i]->mutex);
1580 		d->vqs[i]->iotlb = niotlb;
1581 		mutex_unlock(&d->vqs[i]->mutex);
1582 	}
1583 
1584 	vhost_umem_clean(oiotlb);
1585 
1586 	return 0;
1587 }
1588 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1589 
1590 /* Caller must have device mutex */
1591 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1592 {
1593 	struct file *eventfp, *filep = NULL;
1594 	struct eventfd_ctx *ctx = NULL;
1595 	u64 p;
1596 	long r;
1597 	int i, fd;
1598 
1599 	/* If you are not the owner, you can become one */
1600 	if (ioctl == VHOST_SET_OWNER) {
1601 		r = vhost_dev_set_owner(d);
1602 		goto done;
1603 	}
1604 
1605 	/* You must be the owner to do anything else */
1606 	r = vhost_dev_check_owner(d);
1607 	if (r)
1608 		goto done;
1609 
1610 	switch (ioctl) {
1611 	case VHOST_SET_MEM_TABLE:
1612 		r = vhost_set_memory(d, argp);
1613 		break;
1614 	case VHOST_SET_LOG_BASE:
1615 		if (copy_from_user(&p, argp, sizeof p)) {
1616 			r = -EFAULT;
1617 			break;
1618 		}
1619 		if ((u64)(unsigned long)p != p) {
1620 			r = -EFAULT;
1621 			break;
1622 		}
1623 		for (i = 0; i < d->nvqs; ++i) {
1624 			struct vhost_virtqueue *vq;
1625 			void __user *base = (void __user *)(unsigned long)p;
1626 			vq = d->vqs[i];
1627 			mutex_lock(&vq->mutex);
1628 			/* If ring is inactive, will check when it's enabled. */
1629 			if (vq->private_data && !vq_log_access_ok(vq, base))
1630 				r = -EFAULT;
1631 			else
1632 				vq->log_base = base;
1633 			mutex_unlock(&vq->mutex);
1634 		}
1635 		break;
1636 	case VHOST_SET_LOG_FD:
1637 		r = get_user(fd, (int __user *)argp);
1638 		if (r < 0)
1639 			break;
1640 		eventfp = fd == -1 ? NULL : eventfd_fget(fd);
1641 		if (IS_ERR(eventfp)) {
1642 			r = PTR_ERR(eventfp);
1643 			break;
1644 		}
1645 		if (eventfp != d->log_file) {
1646 			filep = d->log_file;
1647 			d->log_file = eventfp;
1648 			ctx = d->log_ctx;
1649 			d->log_ctx = eventfp ?
1650 				eventfd_ctx_fileget(eventfp) : NULL;
1651 		} else
1652 			filep = eventfp;
1653 		for (i = 0; i < d->nvqs; ++i) {
1654 			mutex_lock(&d->vqs[i]->mutex);
1655 			d->vqs[i]->log_ctx = d->log_ctx;
1656 			mutex_unlock(&d->vqs[i]->mutex);
1657 		}
1658 		if (ctx)
1659 			eventfd_ctx_put(ctx);
1660 		if (filep)
1661 			fput(filep);
1662 		break;
1663 	default:
1664 		r = -ENOIOCTLCMD;
1665 		break;
1666 	}
1667 done:
1668 	return r;
1669 }
1670 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1671 
1672 /* TODO: This is really inefficient.  We need something like get_user()
1673  * (instruction directly accesses the data, with an exception table entry
1674  * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1675  */
1676 static int set_bit_to_user(int nr, void __user *addr)
1677 {
1678 	unsigned long log = (unsigned long)addr;
1679 	struct page *page;
1680 	void *base;
1681 	int bit = nr + (log % PAGE_SIZE) * 8;
1682 	int r;
1683 
1684 	r = get_user_pages_fast(log, 1, 1, &page);
1685 	if (r < 0)
1686 		return r;
1687 	BUG_ON(r != 1);
1688 	base = kmap_atomic(page);
1689 	set_bit(bit, base);
1690 	kunmap_atomic(base);
1691 	set_page_dirty_lock(page);
1692 	put_page(page);
1693 	return 0;
1694 }
1695 
1696 static int log_write(void __user *log_base,
1697 		     u64 write_address, u64 write_length)
1698 {
1699 	u64 write_page = write_address / VHOST_PAGE_SIZE;
1700 	int r;
1701 
1702 	if (!write_length)
1703 		return 0;
1704 	write_length += write_address % VHOST_PAGE_SIZE;
1705 	for (;;) {
1706 		u64 base = (u64)(unsigned long)log_base;
1707 		u64 log = base + write_page / 8;
1708 		int bit = write_page % 8;
1709 		if ((u64)(unsigned long)log != log)
1710 			return -EFAULT;
1711 		r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1712 		if (r < 0)
1713 			return r;
1714 		if (write_length <= VHOST_PAGE_SIZE)
1715 			break;
1716 		write_length -= VHOST_PAGE_SIZE;
1717 		write_page += 1;
1718 	}
1719 	return r;
1720 }
1721 
1722 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1723 		    unsigned int log_num, u64 len)
1724 {
1725 	int i, r;
1726 
1727 	/* Make sure data written is seen before log. */
1728 	smp_wmb();
1729 	for (i = 0; i < log_num; ++i) {
1730 		u64 l = min(log[i].len, len);
1731 		r = log_write(vq->log_base, log[i].addr, l);
1732 		if (r < 0)
1733 			return r;
1734 		len -= l;
1735 		if (!len) {
1736 			if (vq->log_ctx)
1737 				eventfd_signal(vq->log_ctx, 1);
1738 			return 0;
1739 		}
1740 	}
1741 	/* Length written exceeds what we have stored. This is a bug. */
1742 	BUG();
1743 	return 0;
1744 }
1745 EXPORT_SYMBOL_GPL(vhost_log_write);
1746 
1747 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1748 {
1749 	void __user *used;
1750 	if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1751 			   &vq->used->flags) < 0)
1752 		return -EFAULT;
1753 	if (unlikely(vq->log_used)) {
1754 		/* Make sure the flag is seen before log. */
1755 		smp_wmb();
1756 		/* Log used flag write. */
1757 		used = &vq->used->flags;
1758 		log_write(vq->log_base, vq->log_addr +
1759 			  (used - (void __user *)vq->used),
1760 			  sizeof vq->used->flags);
1761 		if (vq->log_ctx)
1762 			eventfd_signal(vq->log_ctx, 1);
1763 	}
1764 	return 0;
1765 }
1766 
1767 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1768 {
1769 	if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1770 			   vhost_avail_event(vq)))
1771 		return -EFAULT;
1772 	if (unlikely(vq->log_used)) {
1773 		void __user *used;
1774 		/* Make sure the event is seen before log. */
1775 		smp_wmb();
1776 		/* Log avail event write */
1777 		used = vhost_avail_event(vq);
1778 		log_write(vq->log_base, vq->log_addr +
1779 			  (used - (void __user *)vq->used),
1780 			  sizeof *vhost_avail_event(vq));
1781 		if (vq->log_ctx)
1782 			eventfd_signal(vq->log_ctx, 1);
1783 	}
1784 	return 0;
1785 }
1786 
1787 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1788 {
1789 	__virtio16 last_used_idx;
1790 	int r;
1791 	bool is_le = vq->is_le;
1792 
1793 	if (!vq->private_data)
1794 		return 0;
1795 
1796 	vhost_init_is_le(vq);
1797 
1798 	r = vhost_update_used_flags(vq);
1799 	if (r)
1800 		goto err;
1801 	vq->signalled_used_valid = false;
1802 	if (!vq->iotlb &&
1803 	    !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1804 		r = -EFAULT;
1805 		goto err;
1806 	}
1807 	r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
1808 	if (r) {
1809 		vq_err(vq, "Can't access used idx at %p\n",
1810 		       &vq->used->idx);
1811 		goto err;
1812 	}
1813 	vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1814 	return 0;
1815 
1816 err:
1817 	vq->is_le = is_le;
1818 	return r;
1819 }
1820 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1821 
1822 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1823 			  struct iovec iov[], int iov_size, int access)
1824 {
1825 	const struct vhost_umem_node *node;
1826 	struct vhost_dev *dev = vq->dev;
1827 	struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1828 	struct iovec *_iov;
1829 	u64 s = 0;
1830 	int ret = 0;
1831 
1832 	while ((u64)len > s) {
1833 		u64 size;
1834 		if (unlikely(ret >= iov_size)) {
1835 			ret = -ENOBUFS;
1836 			break;
1837 		}
1838 
1839 		node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1840 							addr, addr + len - 1);
1841 		if (node == NULL || node->start > addr) {
1842 			if (umem != dev->iotlb) {
1843 				ret = -EFAULT;
1844 				break;
1845 			}
1846 			ret = -EAGAIN;
1847 			break;
1848 		} else if (!(node->perm & access)) {
1849 			ret = -EPERM;
1850 			break;
1851 		}
1852 
1853 		_iov = iov + ret;
1854 		size = node->size - addr + node->start;
1855 		_iov->iov_len = min((u64)len - s, size);
1856 		_iov->iov_base = (void __user *)(unsigned long)
1857 			(node->userspace_addr + addr - node->start);
1858 		s += size;
1859 		addr += size;
1860 		++ret;
1861 	}
1862 
1863 	if (ret == -EAGAIN)
1864 		vhost_iotlb_miss(vq, addr, access);
1865 	return ret;
1866 }
1867 
1868 /* Each buffer in the virtqueues is actually a chain of descriptors.  This
1869  * function returns the next descriptor in the chain,
1870  * or -1U if we're at the end. */
1871 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1872 {
1873 	unsigned int next;
1874 
1875 	/* If this descriptor says it doesn't chain, we're done. */
1876 	if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1877 		return -1U;
1878 
1879 	/* Check they're not leading us off end of descriptors. */
1880 	next = vhost16_to_cpu(vq, desc->next);
1881 	/* Make sure compiler knows to grab that: we don't want it changing! */
1882 	/* We will use the result as an index in an array, so most
1883 	 * architectures only need a compiler barrier here. */
1884 	read_barrier_depends();
1885 
1886 	return next;
1887 }
1888 
1889 static int get_indirect(struct vhost_virtqueue *vq,
1890 			struct iovec iov[], unsigned int iov_size,
1891 			unsigned int *out_num, unsigned int *in_num,
1892 			struct vhost_log *log, unsigned int *log_num,
1893 			struct vring_desc *indirect)
1894 {
1895 	struct vring_desc desc;
1896 	unsigned int i = 0, count, found = 0;
1897 	u32 len = vhost32_to_cpu(vq, indirect->len);
1898 	struct iov_iter from;
1899 	int ret, access;
1900 
1901 	/* Sanity check */
1902 	if (unlikely(len % sizeof desc)) {
1903 		vq_err(vq, "Invalid length in indirect descriptor: "
1904 		       "len 0x%llx not multiple of 0x%zx\n",
1905 		       (unsigned long long)len,
1906 		       sizeof desc);
1907 		return -EINVAL;
1908 	}
1909 
1910 	ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1911 			     UIO_MAXIOV, VHOST_ACCESS_RO);
1912 	if (unlikely(ret < 0)) {
1913 		if (ret != -EAGAIN)
1914 			vq_err(vq, "Translation failure %d in indirect.\n", ret);
1915 		return ret;
1916 	}
1917 	iov_iter_init(&from, READ, vq->indirect, ret, len);
1918 
1919 	/* We will use the result as an address to read from, so most
1920 	 * architectures only need a compiler barrier here. */
1921 	read_barrier_depends();
1922 
1923 	count = len / sizeof desc;
1924 	/* Buffers are chained via a 16 bit next field, so
1925 	 * we can have at most 2^16 of these. */
1926 	if (unlikely(count > USHRT_MAX + 1)) {
1927 		vq_err(vq, "Indirect buffer length too big: %d\n",
1928 		       indirect->len);
1929 		return -E2BIG;
1930 	}
1931 
1932 	do {
1933 		unsigned iov_count = *in_num + *out_num;
1934 		if (unlikely(++found > count)) {
1935 			vq_err(vq, "Loop detected: last one at %u "
1936 			       "indirect size %u\n",
1937 			       i, count);
1938 			return -EINVAL;
1939 		}
1940 		if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1941 			vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1942 			       i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1943 			return -EINVAL;
1944 		}
1945 		if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1946 			vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1947 			       i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1948 			return -EINVAL;
1949 		}
1950 
1951 		if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1952 			access = VHOST_ACCESS_WO;
1953 		else
1954 			access = VHOST_ACCESS_RO;
1955 
1956 		ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1957 				     vhost32_to_cpu(vq, desc.len), iov + iov_count,
1958 				     iov_size - iov_count, access);
1959 		if (unlikely(ret < 0)) {
1960 			if (ret != -EAGAIN)
1961 				vq_err(vq, "Translation failure %d indirect idx %d\n",
1962 					ret, i);
1963 			return ret;
1964 		}
1965 		/* If this is an input descriptor, increment that count. */
1966 		if (access == VHOST_ACCESS_WO) {
1967 			*in_num += ret;
1968 			if (unlikely(log)) {
1969 				log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1970 				log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1971 				++*log_num;
1972 			}
1973 		} else {
1974 			/* If it's an output descriptor, they're all supposed
1975 			 * to come before any input descriptors. */
1976 			if (unlikely(*in_num)) {
1977 				vq_err(vq, "Indirect descriptor "
1978 				       "has out after in: idx %d\n", i);
1979 				return -EINVAL;
1980 			}
1981 			*out_num += ret;
1982 		}
1983 	} while ((i = next_desc(vq, &desc)) != -1);
1984 	return 0;
1985 }
1986 
1987 /* This looks in the virtqueue and for the first available buffer, and converts
1988  * it to an iovec for convenient access.  Since descriptors consist of some
1989  * number of output then some number of input descriptors, it's actually two
1990  * iovecs, but we pack them into one and note how many of each there were.
1991  *
1992  * This function returns the descriptor number found, or vq->num (which is
1993  * never a valid descriptor number) if none was found.  A negative code is
1994  * returned on error. */
1995 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1996 		      struct iovec iov[], unsigned int iov_size,
1997 		      unsigned int *out_num, unsigned int *in_num,
1998 		      struct vhost_log *log, unsigned int *log_num)
1999 {
2000 	struct vring_desc desc;
2001 	unsigned int i, head, found = 0;
2002 	u16 last_avail_idx;
2003 	__virtio16 avail_idx;
2004 	__virtio16 ring_head;
2005 	int ret, access;
2006 
2007 	/* Check it isn't doing very strange things with descriptor numbers. */
2008 	last_avail_idx = vq->last_avail_idx;
2009 
2010 	if (vq->avail_idx == vq->last_avail_idx) {
2011 		if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
2012 			vq_err(vq, "Failed to access avail idx at %p\n",
2013 				&vq->avail->idx);
2014 			return -EFAULT;
2015 		}
2016 		vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2017 
2018 		if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2019 			vq_err(vq, "Guest moved used index from %u to %u",
2020 				last_avail_idx, vq->avail_idx);
2021 			return -EFAULT;
2022 		}
2023 
2024 		/* If there's nothing new since last we looked, return
2025 		 * invalid.
2026 		 */
2027 		if (vq->avail_idx == last_avail_idx)
2028 			return vq->num;
2029 
2030 		/* Only get avail ring entries after they have been
2031 		 * exposed by guest.
2032 		 */
2033 		smp_rmb();
2034 	}
2035 
2036 	/* Grab the next descriptor number they're advertising, and increment
2037 	 * the index we've seen. */
2038 	if (unlikely(vhost_get_avail(vq, ring_head,
2039 		     &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
2040 		vq_err(vq, "Failed to read head: idx %d address %p\n",
2041 		       last_avail_idx,
2042 		       &vq->avail->ring[last_avail_idx % vq->num]);
2043 		return -EFAULT;
2044 	}
2045 
2046 	head = vhost16_to_cpu(vq, ring_head);
2047 
2048 	/* If their number is silly, that's an error. */
2049 	if (unlikely(head >= vq->num)) {
2050 		vq_err(vq, "Guest says index %u > %u is available",
2051 		       head, vq->num);
2052 		return -EINVAL;
2053 	}
2054 
2055 	/* When we start there are none of either input nor output. */
2056 	*out_num = *in_num = 0;
2057 	if (unlikely(log))
2058 		*log_num = 0;
2059 
2060 	i = head;
2061 	do {
2062 		unsigned iov_count = *in_num + *out_num;
2063 		if (unlikely(i >= vq->num)) {
2064 			vq_err(vq, "Desc index is %u > %u, head = %u",
2065 			       i, vq->num, head);
2066 			return -EINVAL;
2067 		}
2068 		if (unlikely(++found > vq->num)) {
2069 			vq_err(vq, "Loop detected: last one at %u "
2070 			       "vq size %u head %u\n",
2071 			       i, vq->num, head);
2072 			return -EINVAL;
2073 		}
2074 		ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
2075 					   sizeof desc);
2076 		if (unlikely(ret)) {
2077 			vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2078 			       i, vq->desc + i);
2079 			return -EFAULT;
2080 		}
2081 		if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2082 			ret = get_indirect(vq, iov, iov_size,
2083 					   out_num, in_num,
2084 					   log, log_num, &desc);
2085 			if (unlikely(ret < 0)) {
2086 				if (ret != -EAGAIN)
2087 					vq_err(vq, "Failure detected "
2088 						"in indirect descriptor at idx %d\n", i);
2089 				return ret;
2090 			}
2091 			continue;
2092 		}
2093 
2094 		if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2095 			access = VHOST_ACCESS_WO;
2096 		else
2097 			access = VHOST_ACCESS_RO;
2098 		ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2099 				     vhost32_to_cpu(vq, desc.len), iov + iov_count,
2100 				     iov_size - iov_count, access);
2101 		if (unlikely(ret < 0)) {
2102 			if (ret != -EAGAIN)
2103 				vq_err(vq, "Translation failure %d descriptor idx %d\n",
2104 					ret, i);
2105 			return ret;
2106 		}
2107 		if (access == VHOST_ACCESS_WO) {
2108 			/* If this is an input descriptor,
2109 			 * increment that count. */
2110 			*in_num += ret;
2111 			if (unlikely(log)) {
2112 				log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2113 				log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2114 				++*log_num;
2115 			}
2116 		} else {
2117 			/* If it's an output descriptor, they're all supposed
2118 			 * to come before any input descriptors. */
2119 			if (unlikely(*in_num)) {
2120 				vq_err(vq, "Descriptor has out after in: "
2121 				       "idx %d\n", i);
2122 				return -EINVAL;
2123 			}
2124 			*out_num += ret;
2125 		}
2126 	} while ((i = next_desc(vq, &desc)) != -1);
2127 
2128 	/* On success, increment avail index. */
2129 	vq->last_avail_idx++;
2130 
2131 	/* Assume notifications from guest are disabled at this point,
2132 	 * if they aren't we would need to update avail_event index. */
2133 	BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2134 	return head;
2135 }
2136 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2137 
2138 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2139 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2140 {
2141 	vq->last_avail_idx -= n;
2142 }
2143 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2144 
2145 /* After we've used one of their buffers, we tell them about it.  We'll then
2146  * want to notify the guest, using eventfd. */
2147 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2148 {
2149 	struct vring_used_elem heads = {
2150 		cpu_to_vhost32(vq, head),
2151 		cpu_to_vhost32(vq, len)
2152 	};
2153 
2154 	return vhost_add_used_n(vq, &heads, 1);
2155 }
2156 EXPORT_SYMBOL_GPL(vhost_add_used);
2157 
2158 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2159 			    struct vring_used_elem *heads,
2160 			    unsigned count)
2161 {
2162 	struct vring_used_elem __user *used;
2163 	u16 old, new;
2164 	int start;
2165 
2166 	start = vq->last_used_idx & (vq->num - 1);
2167 	used = vq->used->ring + start;
2168 	if (count == 1) {
2169 		if (vhost_put_user(vq, heads[0].id, &used->id)) {
2170 			vq_err(vq, "Failed to write used id");
2171 			return -EFAULT;
2172 		}
2173 		if (vhost_put_user(vq, heads[0].len, &used->len)) {
2174 			vq_err(vq, "Failed to write used len");
2175 			return -EFAULT;
2176 		}
2177 	} else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2178 		vq_err(vq, "Failed to write used");
2179 		return -EFAULT;
2180 	}
2181 	if (unlikely(vq->log_used)) {
2182 		/* Make sure data is seen before log. */
2183 		smp_wmb();
2184 		/* Log used ring entry write. */
2185 		log_write(vq->log_base,
2186 			  vq->log_addr +
2187 			   ((void __user *)used - (void __user *)vq->used),
2188 			  count * sizeof *used);
2189 	}
2190 	old = vq->last_used_idx;
2191 	new = (vq->last_used_idx += count);
2192 	/* If the driver never bothers to signal in a very long while,
2193 	 * used index might wrap around. If that happens, invalidate
2194 	 * signalled_used index we stored. TODO: make sure driver
2195 	 * signals at least once in 2^16 and remove this. */
2196 	if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2197 		vq->signalled_used_valid = false;
2198 	return 0;
2199 }
2200 
2201 /* After we've used one of their buffers, we tell them about it.  We'll then
2202  * want to notify the guest, using eventfd. */
2203 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2204 		     unsigned count)
2205 {
2206 	int start, n, r;
2207 
2208 	start = vq->last_used_idx & (vq->num - 1);
2209 	n = vq->num - start;
2210 	if (n < count) {
2211 		r = __vhost_add_used_n(vq, heads, n);
2212 		if (r < 0)
2213 			return r;
2214 		heads += n;
2215 		count -= n;
2216 	}
2217 	r = __vhost_add_used_n(vq, heads, count);
2218 
2219 	/* Make sure buffer is written before we update index. */
2220 	smp_wmb();
2221 	if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2222 			   &vq->used->idx)) {
2223 		vq_err(vq, "Failed to increment used idx");
2224 		return -EFAULT;
2225 	}
2226 	if (unlikely(vq->log_used)) {
2227 		/* Log used index update. */
2228 		log_write(vq->log_base,
2229 			  vq->log_addr + offsetof(struct vring_used, idx),
2230 			  sizeof vq->used->idx);
2231 		if (vq->log_ctx)
2232 			eventfd_signal(vq->log_ctx, 1);
2233 	}
2234 	return r;
2235 }
2236 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2237 
2238 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2239 {
2240 	__u16 old, new;
2241 	__virtio16 event;
2242 	bool v;
2243 	/* Flush out used index updates. This is paired
2244 	 * with the barrier that the Guest executes when enabling
2245 	 * interrupts. */
2246 	smp_mb();
2247 
2248 	if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2249 	    unlikely(vq->avail_idx == vq->last_avail_idx))
2250 		return true;
2251 
2252 	if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2253 		__virtio16 flags;
2254 		if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
2255 			vq_err(vq, "Failed to get flags");
2256 			return true;
2257 		}
2258 		return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2259 	}
2260 	old = vq->signalled_used;
2261 	v = vq->signalled_used_valid;
2262 	new = vq->signalled_used = vq->last_used_idx;
2263 	vq->signalled_used_valid = true;
2264 
2265 	if (unlikely(!v))
2266 		return true;
2267 
2268 	if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
2269 		vq_err(vq, "Failed to get used event idx");
2270 		return true;
2271 	}
2272 	return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2273 }
2274 
2275 /* This actually signals the guest, using eventfd. */
2276 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2277 {
2278 	/* Signal the Guest tell them we used something up. */
2279 	if (vq->call_ctx && vhost_notify(dev, vq))
2280 		eventfd_signal(vq->call_ctx, 1);
2281 }
2282 EXPORT_SYMBOL_GPL(vhost_signal);
2283 
2284 /* And here's the combo meal deal.  Supersize me! */
2285 void vhost_add_used_and_signal(struct vhost_dev *dev,
2286 			       struct vhost_virtqueue *vq,
2287 			       unsigned int head, int len)
2288 {
2289 	vhost_add_used(vq, head, len);
2290 	vhost_signal(dev, vq);
2291 }
2292 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2293 
2294 /* multi-buffer version of vhost_add_used_and_signal */
2295 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2296 				 struct vhost_virtqueue *vq,
2297 				 struct vring_used_elem *heads, unsigned count)
2298 {
2299 	vhost_add_used_n(vq, heads, count);
2300 	vhost_signal(dev, vq);
2301 }
2302 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2303 
2304 /* return true if we're sure that avaiable ring is empty */
2305 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2306 {
2307 	__virtio16 avail_idx;
2308 	int r;
2309 
2310 	if (vq->avail_idx != vq->last_avail_idx)
2311 		return false;
2312 
2313 	r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2314 	if (unlikely(r))
2315 		return false;
2316 	vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2317 
2318 	return vq->avail_idx == vq->last_avail_idx;
2319 }
2320 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2321 
2322 /* OK, now we need to know about added descriptors. */
2323 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2324 {
2325 	__virtio16 avail_idx;
2326 	int r;
2327 
2328 	if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2329 		return false;
2330 	vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2331 	if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2332 		r = vhost_update_used_flags(vq);
2333 		if (r) {
2334 			vq_err(vq, "Failed to enable notification at %p: %d\n",
2335 			       &vq->used->flags, r);
2336 			return false;
2337 		}
2338 	} else {
2339 		r = vhost_update_avail_event(vq, vq->avail_idx);
2340 		if (r) {
2341 			vq_err(vq, "Failed to update avail event index at %p: %d\n",
2342 			       vhost_avail_event(vq), r);
2343 			return false;
2344 		}
2345 	}
2346 	/* They could have slipped one in as we were doing that: make
2347 	 * sure it's written, then check again. */
2348 	smp_mb();
2349 	r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2350 	if (r) {
2351 		vq_err(vq, "Failed to check avail idx at %p: %d\n",
2352 		       &vq->avail->idx, r);
2353 		return false;
2354 	}
2355 
2356 	return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2357 }
2358 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2359 
2360 /* We don't need to be notified again. */
2361 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2362 {
2363 	int r;
2364 
2365 	if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2366 		return;
2367 	vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2368 	if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2369 		r = vhost_update_used_flags(vq);
2370 		if (r)
2371 			vq_err(vq, "Failed to enable notification at %p: %d\n",
2372 			       &vq->used->flags, r);
2373 	}
2374 }
2375 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2376 
2377 /* Create a new message. */
2378 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2379 {
2380 	struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2381 	if (!node)
2382 		return NULL;
2383 	node->vq = vq;
2384 	node->msg.type = type;
2385 	return node;
2386 }
2387 EXPORT_SYMBOL_GPL(vhost_new_msg);
2388 
2389 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2390 		       struct vhost_msg_node *node)
2391 {
2392 	spin_lock(&dev->iotlb_lock);
2393 	list_add_tail(&node->node, head);
2394 	spin_unlock(&dev->iotlb_lock);
2395 
2396 	wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
2397 }
2398 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2399 
2400 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2401 					 struct list_head *head)
2402 {
2403 	struct vhost_msg_node *node = NULL;
2404 
2405 	spin_lock(&dev->iotlb_lock);
2406 	if (!list_empty(head)) {
2407 		node = list_first_entry(head, struct vhost_msg_node,
2408 					node);
2409 		list_del(&node->node);
2410 	}
2411 	spin_unlock(&dev->iotlb_lock);
2412 
2413 	return node;
2414 }
2415 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2416 
2417 
2418 static int __init vhost_init(void)
2419 {
2420 	return 0;
2421 }
2422 
2423 static void __exit vhost_exit(void)
2424 {
2425 }
2426 
2427 module_init(vhost_init);
2428 module_exit(vhost_exit);
2429 
2430 MODULE_VERSION("0.0.1");
2431 MODULE_LICENSE("GPL v2");
2432 MODULE_AUTHOR("Michael S. Tsirkin");
2433 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
2434