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Merge branch 'kvm-ppc-next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus...
[deliverable/linux.git] / drivers / vhost / vhost.c
1 /* Copyright (C) 2009 Red Hat, Inc.
2 * Copyright (C) 2006 Rusty Russell IBM Corporation
3 *
4 * Author: Michael S. Tsirkin <mst@redhat.com>
5 *
6 * Inspiration, some code, and most witty comments come from
7 * Documentation/virtual/lguest/lguest.c, by Rusty Russell
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2.
10 *
11 * Generic code for virtio server in host kernel.
12 */
13
14 #include <linux/eventfd.h>
15 #include <linux/vhost.h>
16 #include <linux/uio.h>
17 #include <linux/mm.h>
18 #include <linux/mmu_context.h>
19 #include <linux/miscdevice.h>
20 #include <linux/mutex.h>
21 #include <linux/poll.h>
22 #include <linux/file.h>
23 #include <linux/highmem.h>
24 #include <linux/slab.h>
25 #include <linux/vmalloc.h>
26 #include <linux/kthread.h>
27 #include <linux/cgroup.h>
28 #include <linux/module.h>
29 #include <linux/sort.h>
30
31 #include "vhost.h"
32
33 static ushort max_mem_regions = 64;
34 module_param(max_mem_regions, ushort, 0444);
35 MODULE_PARM_DESC(max_mem_regions,
36 "Maximum number of memory regions in memory map. (default: 64)");
37
38 enum {
39 VHOST_MEMORY_F_LOG = 0x1,
40 };
41
42 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
43 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
44
45 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
46 static void vhost_vq_reset_user_be(struct vhost_virtqueue *vq)
47 {
48 vq->user_be = !virtio_legacy_is_little_endian();
49 }
50
51 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
52 {
53 struct vhost_vring_state s;
54
55 if (vq->private_data)
56 return -EBUSY;
57
58 if (copy_from_user(&s, argp, sizeof(s)))
59 return -EFAULT;
60
61 if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
62 s.num != VHOST_VRING_BIG_ENDIAN)
63 return -EINVAL;
64
65 vq->user_be = s.num;
66
67 return 0;
68 }
69
70 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
71 int __user *argp)
72 {
73 struct vhost_vring_state s = {
74 .index = idx,
75 .num = vq->user_be
76 };
77
78 if (copy_to_user(argp, &s, sizeof(s)))
79 return -EFAULT;
80
81 return 0;
82 }
83
84 static void vhost_init_is_le(struct vhost_virtqueue *vq)
85 {
86 /* Note for legacy virtio: user_be is initialized at reset time
87 * according to the host endianness. If userspace does not set an
88 * explicit endianness, the default behavior is native endian, as
89 * expected by legacy virtio.
90 */
91 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
92 }
93 #else
94 static void vhost_vq_reset_user_be(struct vhost_virtqueue *vq)
95 {
96 }
97
98 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
99 {
100 return -ENOIOCTLCMD;
101 }
102
103 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
104 int __user *argp)
105 {
106 return -ENOIOCTLCMD;
107 }
108
109 static void vhost_init_is_le(struct vhost_virtqueue *vq)
110 {
111 if (vhost_has_feature(vq, VIRTIO_F_VERSION_1))
112 vq->is_le = true;
113 }
114 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
115
116 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
117 poll_table *pt)
118 {
119 struct vhost_poll *poll;
120
121 poll = container_of(pt, struct vhost_poll, table);
122 poll->wqh = wqh;
123 add_wait_queue(wqh, &poll->wait);
124 }
125
126 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
127 void *key)
128 {
129 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
130
131 if (!((unsigned long)key & poll->mask))
132 return 0;
133
134 vhost_poll_queue(poll);
135 return 0;
136 }
137
138 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
139 {
140 INIT_LIST_HEAD(&work->node);
141 work->fn = fn;
142 init_waitqueue_head(&work->done);
143 work->flushing = 0;
144 work->queue_seq = work->done_seq = 0;
145 }
146 EXPORT_SYMBOL_GPL(vhost_work_init);
147
148 /* Init poll structure */
149 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
150 unsigned long mask, struct vhost_dev *dev)
151 {
152 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
153 init_poll_funcptr(&poll->table, vhost_poll_func);
154 poll->mask = mask;
155 poll->dev = dev;
156 poll->wqh = NULL;
157
158 vhost_work_init(&poll->work, fn);
159 }
160 EXPORT_SYMBOL_GPL(vhost_poll_init);
161
162 /* Start polling a file. We add ourselves to file's wait queue. The caller must
163 * keep a reference to a file until after vhost_poll_stop is called. */
164 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
165 {
166 unsigned long mask;
167 int ret = 0;
168
169 if (poll->wqh)
170 return 0;
171
172 mask = file->f_op->poll(file, &poll->table);
173 if (mask)
174 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
175 if (mask & POLLERR) {
176 if (poll->wqh)
177 remove_wait_queue(poll->wqh, &poll->wait);
178 ret = -EINVAL;
179 }
180
181 return ret;
182 }
183 EXPORT_SYMBOL_GPL(vhost_poll_start);
184
185 /* Stop polling a file. After this function returns, it becomes safe to drop the
186 * file reference. You must also flush afterwards. */
187 void vhost_poll_stop(struct vhost_poll *poll)
188 {
189 if (poll->wqh) {
190 remove_wait_queue(poll->wqh, &poll->wait);
191 poll->wqh = NULL;
192 }
193 }
194 EXPORT_SYMBOL_GPL(vhost_poll_stop);
195
196 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
197 unsigned seq)
198 {
199 int left;
200
201 spin_lock_irq(&dev->work_lock);
202 left = seq - work->done_seq;
203 spin_unlock_irq(&dev->work_lock);
204 return left <= 0;
205 }
206
207 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
208 {
209 unsigned seq;
210 int flushing;
211
212 spin_lock_irq(&dev->work_lock);
213 seq = work->queue_seq;
214 work->flushing++;
215 spin_unlock_irq(&dev->work_lock);
216 wait_event(work->done, vhost_work_seq_done(dev, work, seq));
217 spin_lock_irq(&dev->work_lock);
218 flushing = --work->flushing;
219 spin_unlock_irq(&dev->work_lock);
220 BUG_ON(flushing < 0);
221 }
222 EXPORT_SYMBOL_GPL(vhost_work_flush);
223
224 /* Flush any work that has been scheduled. When calling this, don't hold any
225 * locks that are also used by the callback. */
226 void vhost_poll_flush(struct vhost_poll *poll)
227 {
228 vhost_work_flush(poll->dev, &poll->work);
229 }
230 EXPORT_SYMBOL_GPL(vhost_poll_flush);
231
232 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
233 {
234 unsigned long flags;
235
236 spin_lock_irqsave(&dev->work_lock, flags);
237 if (list_empty(&work->node)) {
238 list_add_tail(&work->node, &dev->work_list);
239 work->queue_seq++;
240 spin_unlock_irqrestore(&dev->work_lock, flags);
241 wake_up_process(dev->worker);
242 } else {
243 spin_unlock_irqrestore(&dev->work_lock, flags);
244 }
245 }
246 EXPORT_SYMBOL_GPL(vhost_work_queue);
247
248 void vhost_poll_queue(struct vhost_poll *poll)
249 {
250 vhost_work_queue(poll->dev, &poll->work);
251 }
252 EXPORT_SYMBOL_GPL(vhost_poll_queue);
253
254 static void vhost_vq_reset(struct vhost_dev *dev,
255 struct vhost_virtqueue *vq)
256 {
257 vq->num = 1;
258 vq->desc = NULL;
259 vq->avail = NULL;
260 vq->used = NULL;
261 vq->last_avail_idx = 0;
262 vq->avail_idx = 0;
263 vq->last_used_idx = 0;
264 vq->signalled_used = 0;
265 vq->signalled_used_valid = false;
266 vq->used_flags = 0;
267 vq->log_used = false;
268 vq->log_addr = -1ull;
269 vq->private_data = NULL;
270 vq->acked_features = 0;
271 vq->log_base = NULL;
272 vq->error_ctx = NULL;
273 vq->error = NULL;
274 vq->kick = NULL;
275 vq->call_ctx = NULL;
276 vq->call = NULL;
277 vq->log_ctx = NULL;
278 vq->memory = NULL;
279 vq->is_le = virtio_legacy_is_little_endian();
280 vhost_vq_reset_user_be(vq);
281 }
282
283 static int vhost_worker(void *data)
284 {
285 struct vhost_dev *dev = data;
286 struct vhost_work *work = NULL;
287 unsigned uninitialized_var(seq);
288 mm_segment_t oldfs = get_fs();
289
290 set_fs(USER_DS);
291 use_mm(dev->mm);
292
293 for (;;) {
294 /* mb paired w/ kthread_stop */
295 set_current_state(TASK_INTERRUPTIBLE);
296
297 spin_lock_irq(&dev->work_lock);
298 if (work) {
299 work->done_seq = seq;
300 if (work->flushing)
301 wake_up_all(&work->done);
302 }
303
304 if (kthread_should_stop()) {
305 spin_unlock_irq(&dev->work_lock);
306 __set_current_state(TASK_RUNNING);
307 break;
308 }
309 if (!list_empty(&dev->work_list)) {
310 work = list_first_entry(&dev->work_list,
311 struct vhost_work, node);
312 list_del_init(&work->node);
313 seq = work->queue_seq;
314 } else
315 work = NULL;
316 spin_unlock_irq(&dev->work_lock);
317
318 if (work) {
319 __set_current_state(TASK_RUNNING);
320 work->fn(work);
321 if (need_resched())
322 schedule();
323 } else
324 schedule();
325
326 }
327 unuse_mm(dev->mm);
328 set_fs(oldfs);
329 return 0;
330 }
331
332 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
333 {
334 kfree(vq->indirect);
335 vq->indirect = NULL;
336 kfree(vq->log);
337 vq->log = NULL;
338 kfree(vq->heads);
339 vq->heads = NULL;
340 }
341
342 /* Helper to allocate iovec buffers for all vqs. */
343 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
344 {
345 struct vhost_virtqueue *vq;
346 int i;
347
348 for (i = 0; i < dev->nvqs; ++i) {
349 vq = dev->vqs[i];
350 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
351 GFP_KERNEL);
352 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
353 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
354 if (!vq->indirect || !vq->log || !vq->heads)
355 goto err_nomem;
356 }
357 return 0;
358
359 err_nomem:
360 for (; i >= 0; --i)
361 vhost_vq_free_iovecs(dev->vqs[i]);
362 return -ENOMEM;
363 }
364
365 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
366 {
367 int i;
368
369 for (i = 0; i < dev->nvqs; ++i)
370 vhost_vq_free_iovecs(dev->vqs[i]);
371 }
372
373 void vhost_dev_init(struct vhost_dev *dev,
374 struct vhost_virtqueue **vqs, int nvqs)
375 {
376 struct vhost_virtqueue *vq;
377 int i;
378
379 dev->vqs = vqs;
380 dev->nvqs = nvqs;
381 mutex_init(&dev->mutex);
382 dev->log_ctx = NULL;
383 dev->log_file = NULL;
384 dev->memory = NULL;
385 dev->mm = NULL;
386 spin_lock_init(&dev->work_lock);
387 INIT_LIST_HEAD(&dev->work_list);
388 dev->worker = NULL;
389
390 for (i = 0; i < dev->nvqs; ++i) {
391 vq = dev->vqs[i];
392 vq->log = NULL;
393 vq->indirect = NULL;
394 vq->heads = NULL;
395 vq->dev = dev;
396 mutex_init(&vq->mutex);
397 vhost_vq_reset(dev, vq);
398 if (vq->handle_kick)
399 vhost_poll_init(&vq->poll, vq->handle_kick,
400 POLLIN, dev);
401 }
402 }
403 EXPORT_SYMBOL_GPL(vhost_dev_init);
404
405 /* Caller should have device mutex */
406 long vhost_dev_check_owner(struct vhost_dev *dev)
407 {
408 /* Are you the owner? If not, I don't think you mean to do that */
409 return dev->mm == current->mm ? 0 : -EPERM;
410 }
411 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
412
413 struct vhost_attach_cgroups_struct {
414 struct vhost_work work;
415 struct task_struct *owner;
416 int ret;
417 };
418
419 static void vhost_attach_cgroups_work(struct vhost_work *work)
420 {
421 struct vhost_attach_cgroups_struct *s;
422
423 s = container_of(work, struct vhost_attach_cgroups_struct, work);
424 s->ret = cgroup_attach_task_all(s->owner, current);
425 }
426
427 static int vhost_attach_cgroups(struct vhost_dev *dev)
428 {
429 struct vhost_attach_cgroups_struct attach;
430
431 attach.owner = current;
432 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
433 vhost_work_queue(dev, &attach.work);
434 vhost_work_flush(dev, &attach.work);
435 return attach.ret;
436 }
437
438 /* Caller should have device mutex */
439 bool vhost_dev_has_owner(struct vhost_dev *dev)
440 {
441 return dev->mm;
442 }
443 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
444
445 /* Caller should have device mutex */
446 long vhost_dev_set_owner(struct vhost_dev *dev)
447 {
448 struct task_struct *worker;
449 int err;
450
451 /* Is there an owner already? */
452 if (vhost_dev_has_owner(dev)) {
453 err = -EBUSY;
454 goto err_mm;
455 }
456
457 /* No owner, become one */
458 dev->mm = get_task_mm(current);
459 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
460 if (IS_ERR(worker)) {
461 err = PTR_ERR(worker);
462 goto err_worker;
463 }
464
465 dev->worker = worker;
466 wake_up_process(worker); /* avoid contributing to loadavg */
467
468 err = vhost_attach_cgroups(dev);
469 if (err)
470 goto err_cgroup;
471
472 err = vhost_dev_alloc_iovecs(dev);
473 if (err)
474 goto err_cgroup;
475
476 return 0;
477 err_cgroup:
478 kthread_stop(worker);
479 dev->worker = NULL;
480 err_worker:
481 if (dev->mm)
482 mmput(dev->mm);
483 dev->mm = NULL;
484 err_mm:
485 return err;
486 }
487 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
488
489 struct vhost_memory *vhost_dev_reset_owner_prepare(void)
490 {
491 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
492 }
493 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
494
495 /* Caller should have device mutex */
496 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory)
497 {
498 int i;
499
500 vhost_dev_cleanup(dev, true);
501
502 /* Restore memory to default empty mapping. */
503 memory->nregions = 0;
504 dev->memory = memory;
505 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
506 * VQs aren't running.
507 */
508 for (i = 0; i < dev->nvqs; ++i)
509 dev->vqs[i]->memory = memory;
510 }
511 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
512
513 void vhost_dev_stop(struct vhost_dev *dev)
514 {
515 int i;
516
517 for (i = 0; i < dev->nvqs; ++i) {
518 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
519 vhost_poll_stop(&dev->vqs[i]->poll);
520 vhost_poll_flush(&dev->vqs[i]->poll);
521 }
522 }
523 }
524 EXPORT_SYMBOL_GPL(vhost_dev_stop);
525
526 /* Caller should have device mutex if and only if locked is set */
527 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
528 {
529 int i;
530
531 for (i = 0; i < dev->nvqs; ++i) {
532 if (dev->vqs[i]->error_ctx)
533 eventfd_ctx_put(dev->vqs[i]->error_ctx);
534 if (dev->vqs[i]->error)
535 fput(dev->vqs[i]->error);
536 if (dev->vqs[i]->kick)
537 fput(dev->vqs[i]->kick);
538 if (dev->vqs[i]->call_ctx)
539 eventfd_ctx_put(dev->vqs[i]->call_ctx);
540 if (dev->vqs[i]->call)
541 fput(dev->vqs[i]->call);
542 vhost_vq_reset(dev, dev->vqs[i]);
543 }
544 vhost_dev_free_iovecs(dev);
545 if (dev->log_ctx)
546 eventfd_ctx_put(dev->log_ctx);
547 dev->log_ctx = NULL;
548 if (dev->log_file)
549 fput(dev->log_file);
550 dev->log_file = NULL;
551 /* No one will access memory at this point */
552 kvfree(dev->memory);
553 dev->memory = NULL;
554 WARN_ON(!list_empty(&dev->work_list));
555 if (dev->worker) {
556 kthread_stop(dev->worker);
557 dev->worker = NULL;
558 }
559 if (dev->mm)
560 mmput(dev->mm);
561 dev->mm = NULL;
562 }
563 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
564
565 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
566 {
567 u64 a = addr / VHOST_PAGE_SIZE / 8;
568
569 /* Make sure 64 bit math will not overflow. */
570 if (a > ULONG_MAX - (unsigned long)log_base ||
571 a + (unsigned long)log_base > ULONG_MAX)
572 return 0;
573
574 return access_ok(VERIFY_WRITE, log_base + a,
575 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
576 }
577
578 /* Caller should have vq mutex and device mutex. */
579 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
580 int log_all)
581 {
582 int i;
583
584 if (!mem)
585 return 0;
586
587 for (i = 0; i < mem->nregions; ++i) {
588 struct vhost_memory_region *m = mem->regions + i;
589 unsigned long a = m->userspace_addr;
590 if (m->memory_size > ULONG_MAX)
591 return 0;
592 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
593 m->memory_size))
594 return 0;
595 else if (log_all && !log_access_ok(log_base,
596 m->guest_phys_addr,
597 m->memory_size))
598 return 0;
599 }
600 return 1;
601 }
602
603 /* Can we switch to this memory table? */
604 /* Caller should have device mutex but not vq mutex */
605 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
606 int log_all)
607 {
608 int i;
609
610 for (i = 0; i < d->nvqs; ++i) {
611 int ok;
612 bool log;
613
614 mutex_lock(&d->vqs[i]->mutex);
615 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
616 /* If ring is inactive, will check when it's enabled. */
617 if (d->vqs[i]->private_data)
618 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log);
619 else
620 ok = 1;
621 mutex_unlock(&d->vqs[i]->mutex);
622 if (!ok)
623 return 0;
624 }
625 return 1;
626 }
627
628 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
629 struct vring_desc __user *desc,
630 struct vring_avail __user *avail,
631 struct vring_used __user *used)
632 {
633 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
634 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
635 access_ok(VERIFY_READ, avail,
636 sizeof *avail + num * sizeof *avail->ring + s) &&
637 access_ok(VERIFY_WRITE, used,
638 sizeof *used + num * sizeof *used->ring + s);
639 }
640
641 /* Can we log writes? */
642 /* Caller should have device mutex but not vq mutex */
643 int vhost_log_access_ok(struct vhost_dev *dev)
644 {
645 return memory_access_ok(dev, dev->memory, 1);
646 }
647 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
648
649 /* Verify access for write logging. */
650 /* Caller should have vq mutex and device mutex */
651 static int vq_log_access_ok(struct vhost_virtqueue *vq,
652 void __user *log_base)
653 {
654 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
655
656 return vq_memory_access_ok(log_base, vq->memory,
657 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
658 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
659 sizeof *vq->used +
660 vq->num * sizeof *vq->used->ring + s));
661 }
662
663 /* Can we start vq? */
664 /* Caller should have vq mutex and device mutex */
665 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
666 {
667 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
668 vq_log_access_ok(vq, vq->log_base);
669 }
670 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
671
672 static int vhost_memory_reg_sort_cmp(const void *p1, const void *p2)
673 {
674 const struct vhost_memory_region *r1 = p1, *r2 = p2;
675 if (r1->guest_phys_addr < r2->guest_phys_addr)
676 return 1;
677 if (r1->guest_phys_addr > r2->guest_phys_addr)
678 return -1;
679 return 0;
680 }
681
682 static void *vhost_kvzalloc(unsigned long size)
683 {
684 void *n = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
685
686 if (!n)
687 n = vzalloc(size);
688 return n;
689 }
690
691 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
692 {
693 struct vhost_memory mem, *newmem, *oldmem;
694 unsigned long size = offsetof(struct vhost_memory, regions);
695 int i;
696
697 if (copy_from_user(&mem, m, size))
698 return -EFAULT;
699 if (mem.padding)
700 return -EOPNOTSUPP;
701 if (mem.nregions > max_mem_regions)
702 return -E2BIG;
703 newmem = vhost_kvzalloc(size + mem.nregions * sizeof(*m->regions));
704 if (!newmem)
705 return -ENOMEM;
706
707 memcpy(newmem, &mem, size);
708 if (copy_from_user(newmem->regions, m->regions,
709 mem.nregions * sizeof *m->regions)) {
710 kvfree(newmem);
711 return -EFAULT;
712 }
713 sort(newmem->regions, newmem->nregions, sizeof(*newmem->regions),
714 vhost_memory_reg_sort_cmp, NULL);
715
716 if (!memory_access_ok(d, newmem, 0)) {
717 kvfree(newmem);
718 return -EFAULT;
719 }
720 oldmem = d->memory;
721 d->memory = newmem;
722
723 /* All memory accesses are done under some VQ mutex. */
724 for (i = 0; i < d->nvqs; ++i) {
725 mutex_lock(&d->vqs[i]->mutex);
726 d->vqs[i]->memory = newmem;
727 mutex_unlock(&d->vqs[i]->mutex);
728 }
729 kvfree(oldmem);
730 return 0;
731 }
732
733 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
734 {
735 struct file *eventfp, *filep = NULL;
736 bool pollstart = false, pollstop = false;
737 struct eventfd_ctx *ctx = NULL;
738 u32 __user *idxp = argp;
739 struct vhost_virtqueue *vq;
740 struct vhost_vring_state s;
741 struct vhost_vring_file f;
742 struct vhost_vring_addr a;
743 u32 idx;
744 long r;
745
746 r = get_user(idx, idxp);
747 if (r < 0)
748 return r;
749 if (idx >= d->nvqs)
750 return -ENOBUFS;
751
752 vq = d->vqs[idx];
753
754 mutex_lock(&vq->mutex);
755
756 switch (ioctl) {
757 case VHOST_SET_VRING_NUM:
758 /* Resizing ring with an active backend?
759 * You don't want to do that. */
760 if (vq->private_data) {
761 r = -EBUSY;
762 break;
763 }
764 if (copy_from_user(&s, argp, sizeof s)) {
765 r = -EFAULT;
766 break;
767 }
768 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
769 r = -EINVAL;
770 break;
771 }
772 vq->num = s.num;
773 break;
774 case VHOST_SET_VRING_BASE:
775 /* Moving base with an active backend?
776 * You don't want to do that. */
777 if (vq->private_data) {
778 r = -EBUSY;
779 break;
780 }
781 if (copy_from_user(&s, argp, sizeof s)) {
782 r = -EFAULT;
783 break;
784 }
785 if (s.num > 0xffff) {
786 r = -EINVAL;
787 break;
788 }
789 vq->last_avail_idx = s.num;
790 /* Forget the cached index value. */
791 vq->avail_idx = vq->last_avail_idx;
792 break;
793 case VHOST_GET_VRING_BASE:
794 s.index = idx;
795 s.num = vq->last_avail_idx;
796 if (copy_to_user(argp, &s, sizeof s))
797 r = -EFAULT;
798 break;
799 case VHOST_SET_VRING_ADDR:
800 if (copy_from_user(&a, argp, sizeof a)) {
801 r = -EFAULT;
802 break;
803 }
804 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
805 r = -EOPNOTSUPP;
806 break;
807 }
808 /* For 32bit, verify that the top 32bits of the user
809 data are set to zero. */
810 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
811 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
812 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
813 r = -EFAULT;
814 break;
815 }
816
817 /* Make sure it's safe to cast pointers to vring types. */
818 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
819 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
820 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
821 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
822 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
823 r = -EINVAL;
824 break;
825 }
826
827 /* We only verify access here if backend is configured.
828 * If it is not, we don't as size might not have been setup.
829 * We will verify when backend is configured. */
830 if (vq->private_data) {
831 if (!vq_access_ok(vq, vq->num,
832 (void __user *)(unsigned long)a.desc_user_addr,
833 (void __user *)(unsigned long)a.avail_user_addr,
834 (void __user *)(unsigned long)a.used_user_addr)) {
835 r = -EINVAL;
836 break;
837 }
838
839 /* Also validate log access for used ring if enabled. */
840 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
841 !log_access_ok(vq->log_base, a.log_guest_addr,
842 sizeof *vq->used +
843 vq->num * sizeof *vq->used->ring)) {
844 r = -EINVAL;
845 break;
846 }
847 }
848
849 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
850 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
851 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
852 vq->log_addr = a.log_guest_addr;
853 vq->used = (void __user *)(unsigned long)a.used_user_addr;
854 break;
855 case VHOST_SET_VRING_KICK:
856 if (copy_from_user(&f, argp, sizeof f)) {
857 r = -EFAULT;
858 break;
859 }
860 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
861 if (IS_ERR(eventfp)) {
862 r = PTR_ERR(eventfp);
863 break;
864 }
865 if (eventfp != vq->kick) {
866 pollstop = (filep = vq->kick) != NULL;
867 pollstart = (vq->kick = eventfp) != NULL;
868 } else
869 filep = eventfp;
870 break;
871 case VHOST_SET_VRING_CALL:
872 if (copy_from_user(&f, argp, sizeof f)) {
873 r = -EFAULT;
874 break;
875 }
876 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
877 if (IS_ERR(eventfp)) {
878 r = PTR_ERR(eventfp);
879 break;
880 }
881 if (eventfp != vq->call) {
882 filep = vq->call;
883 ctx = vq->call_ctx;
884 vq->call = eventfp;
885 vq->call_ctx = eventfp ?
886 eventfd_ctx_fileget(eventfp) : NULL;
887 } else
888 filep = eventfp;
889 break;
890 case VHOST_SET_VRING_ERR:
891 if (copy_from_user(&f, argp, sizeof f)) {
892 r = -EFAULT;
893 break;
894 }
895 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
896 if (IS_ERR(eventfp)) {
897 r = PTR_ERR(eventfp);
898 break;
899 }
900 if (eventfp != vq->error) {
901 filep = vq->error;
902 vq->error = eventfp;
903 ctx = vq->error_ctx;
904 vq->error_ctx = eventfp ?
905 eventfd_ctx_fileget(eventfp) : NULL;
906 } else
907 filep = eventfp;
908 break;
909 case VHOST_SET_VRING_ENDIAN:
910 r = vhost_set_vring_endian(vq, argp);
911 break;
912 case VHOST_GET_VRING_ENDIAN:
913 r = vhost_get_vring_endian(vq, idx, argp);
914 break;
915 default:
916 r = -ENOIOCTLCMD;
917 }
918
919 if (pollstop && vq->handle_kick)
920 vhost_poll_stop(&vq->poll);
921
922 if (ctx)
923 eventfd_ctx_put(ctx);
924 if (filep)
925 fput(filep);
926
927 if (pollstart && vq->handle_kick)
928 r = vhost_poll_start(&vq->poll, vq->kick);
929
930 mutex_unlock(&vq->mutex);
931
932 if (pollstop && vq->handle_kick)
933 vhost_poll_flush(&vq->poll);
934 return r;
935 }
936 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
937
938 /* Caller must have device mutex */
939 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
940 {
941 struct file *eventfp, *filep = NULL;
942 struct eventfd_ctx *ctx = NULL;
943 u64 p;
944 long r;
945 int i, fd;
946
947 /* If you are not the owner, you can become one */
948 if (ioctl == VHOST_SET_OWNER) {
949 r = vhost_dev_set_owner(d);
950 goto done;
951 }
952
953 /* You must be the owner to do anything else */
954 r = vhost_dev_check_owner(d);
955 if (r)
956 goto done;
957
958 switch (ioctl) {
959 case VHOST_SET_MEM_TABLE:
960 r = vhost_set_memory(d, argp);
961 break;
962 case VHOST_SET_LOG_BASE:
963 if (copy_from_user(&p, argp, sizeof p)) {
964 r = -EFAULT;
965 break;
966 }
967 if ((u64)(unsigned long)p != p) {
968 r = -EFAULT;
969 break;
970 }
971 for (i = 0; i < d->nvqs; ++i) {
972 struct vhost_virtqueue *vq;
973 void __user *base = (void __user *)(unsigned long)p;
974 vq = d->vqs[i];
975 mutex_lock(&vq->mutex);
976 /* If ring is inactive, will check when it's enabled. */
977 if (vq->private_data && !vq_log_access_ok(vq, base))
978 r = -EFAULT;
979 else
980 vq->log_base = base;
981 mutex_unlock(&vq->mutex);
982 }
983 break;
984 case VHOST_SET_LOG_FD:
985 r = get_user(fd, (int __user *)argp);
986 if (r < 0)
987 break;
988 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
989 if (IS_ERR(eventfp)) {
990 r = PTR_ERR(eventfp);
991 break;
992 }
993 if (eventfp != d->log_file) {
994 filep = d->log_file;
995 d->log_file = eventfp;
996 ctx = d->log_ctx;
997 d->log_ctx = eventfp ?
998 eventfd_ctx_fileget(eventfp) : NULL;
999 } else
1000 filep = eventfp;
1001 for (i = 0; i < d->nvqs; ++i) {
1002 mutex_lock(&d->vqs[i]->mutex);
1003 d->vqs[i]->log_ctx = d->log_ctx;
1004 mutex_unlock(&d->vqs[i]->mutex);
1005 }
1006 if (ctx)
1007 eventfd_ctx_put(ctx);
1008 if (filep)
1009 fput(filep);
1010 break;
1011 default:
1012 r = -ENOIOCTLCMD;
1013 break;
1014 }
1015 done:
1016 return r;
1017 }
1018 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1019
1020 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
1021 __u64 addr, __u32 len)
1022 {
1023 const struct vhost_memory_region *reg;
1024 int start = 0, end = mem->nregions;
1025
1026 while (start < end) {
1027 int slot = start + (end - start) / 2;
1028 reg = mem->regions + slot;
1029 if (addr >= reg->guest_phys_addr)
1030 end = slot;
1031 else
1032 start = slot + 1;
1033 }
1034
1035 reg = mem->regions + start;
1036 if (addr >= reg->guest_phys_addr &&
1037 reg->guest_phys_addr + reg->memory_size > addr)
1038 return reg;
1039 return NULL;
1040 }
1041
1042 /* TODO: This is really inefficient. We need something like get_user()
1043 * (instruction directly accesses the data, with an exception table entry
1044 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1045 */
1046 static int set_bit_to_user(int nr, void __user *addr)
1047 {
1048 unsigned long log = (unsigned long)addr;
1049 struct page *page;
1050 void *base;
1051 int bit = nr + (log % PAGE_SIZE) * 8;
1052 int r;
1053
1054 r = get_user_pages_fast(log, 1, 1, &page);
1055 if (r < 0)
1056 return r;
1057 BUG_ON(r != 1);
1058 base = kmap_atomic(page);
1059 set_bit(bit, base);
1060 kunmap_atomic(base);
1061 set_page_dirty_lock(page);
1062 put_page(page);
1063 return 0;
1064 }
1065
1066 static int log_write(void __user *log_base,
1067 u64 write_address, u64 write_length)
1068 {
1069 u64 write_page = write_address / VHOST_PAGE_SIZE;
1070 int r;
1071
1072 if (!write_length)
1073 return 0;
1074 write_length += write_address % VHOST_PAGE_SIZE;
1075 for (;;) {
1076 u64 base = (u64)(unsigned long)log_base;
1077 u64 log = base + write_page / 8;
1078 int bit = write_page % 8;
1079 if ((u64)(unsigned long)log != log)
1080 return -EFAULT;
1081 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1082 if (r < 0)
1083 return r;
1084 if (write_length <= VHOST_PAGE_SIZE)
1085 break;
1086 write_length -= VHOST_PAGE_SIZE;
1087 write_page += 1;
1088 }
1089 return r;
1090 }
1091
1092 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1093 unsigned int log_num, u64 len)
1094 {
1095 int i, r;
1096
1097 /* Make sure data written is seen before log. */
1098 smp_wmb();
1099 for (i = 0; i < log_num; ++i) {
1100 u64 l = min(log[i].len, len);
1101 r = log_write(vq->log_base, log[i].addr, l);
1102 if (r < 0)
1103 return r;
1104 len -= l;
1105 if (!len) {
1106 if (vq->log_ctx)
1107 eventfd_signal(vq->log_ctx, 1);
1108 return 0;
1109 }
1110 }
1111 /* Length written exceeds what we have stored. This is a bug. */
1112 BUG();
1113 return 0;
1114 }
1115 EXPORT_SYMBOL_GPL(vhost_log_write);
1116
1117 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1118 {
1119 void __user *used;
1120 if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0)
1121 return -EFAULT;
1122 if (unlikely(vq->log_used)) {
1123 /* Make sure the flag is seen before log. */
1124 smp_wmb();
1125 /* Log used flag write. */
1126 used = &vq->used->flags;
1127 log_write(vq->log_base, vq->log_addr +
1128 (used - (void __user *)vq->used),
1129 sizeof vq->used->flags);
1130 if (vq->log_ctx)
1131 eventfd_signal(vq->log_ctx, 1);
1132 }
1133 return 0;
1134 }
1135
1136 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1137 {
1138 if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq)))
1139 return -EFAULT;
1140 if (unlikely(vq->log_used)) {
1141 void __user *used;
1142 /* Make sure the event is seen before log. */
1143 smp_wmb();
1144 /* Log avail event write */
1145 used = vhost_avail_event(vq);
1146 log_write(vq->log_base, vq->log_addr +
1147 (used - (void __user *)vq->used),
1148 sizeof *vhost_avail_event(vq));
1149 if (vq->log_ctx)
1150 eventfd_signal(vq->log_ctx, 1);
1151 }
1152 return 0;
1153 }
1154
1155 int vhost_init_used(struct vhost_virtqueue *vq)
1156 {
1157 __virtio16 last_used_idx;
1158 int r;
1159 if (!vq->private_data) {
1160 vq->is_le = virtio_legacy_is_little_endian();
1161 return 0;
1162 }
1163
1164 vhost_init_is_le(vq);
1165
1166 r = vhost_update_used_flags(vq);
1167 if (r)
1168 return r;
1169 vq->signalled_used_valid = false;
1170 if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx))
1171 return -EFAULT;
1172 r = __get_user(last_used_idx, &vq->used->idx);
1173 if (r)
1174 return r;
1175 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1176 return 0;
1177 }
1178 EXPORT_SYMBOL_GPL(vhost_init_used);
1179
1180 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1181 struct iovec iov[], int iov_size)
1182 {
1183 const struct vhost_memory_region *reg;
1184 struct vhost_memory *mem;
1185 struct iovec *_iov;
1186 u64 s = 0;
1187 int ret = 0;
1188
1189 mem = vq->memory;
1190 while ((u64)len > s) {
1191 u64 size;
1192 if (unlikely(ret >= iov_size)) {
1193 ret = -ENOBUFS;
1194 break;
1195 }
1196 reg = find_region(mem, addr, len);
1197 if (unlikely(!reg)) {
1198 ret = -EFAULT;
1199 break;
1200 }
1201 _iov = iov + ret;
1202 size = reg->memory_size - addr + reg->guest_phys_addr;
1203 _iov->iov_len = min((u64)len - s, size);
1204 _iov->iov_base = (void __user *)(unsigned long)
1205 (reg->userspace_addr + addr - reg->guest_phys_addr);
1206 s += size;
1207 addr += size;
1208 ++ret;
1209 }
1210
1211 return ret;
1212 }
1213
1214 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1215 * function returns the next descriptor in the chain,
1216 * or -1U if we're at the end. */
1217 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1218 {
1219 unsigned int next;
1220
1221 /* If this descriptor says it doesn't chain, we're done. */
1222 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1223 return -1U;
1224
1225 /* Check they're not leading us off end of descriptors. */
1226 next = vhost16_to_cpu(vq, desc->next);
1227 /* Make sure compiler knows to grab that: we don't want it changing! */
1228 /* We will use the result as an index in an array, so most
1229 * architectures only need a compiler barrier here. */
1230 read_barrier_depends();
1231
1232 return next;
1233 }
1234
1235 static int get_indirect(struct vhost_virtqueue *vq,
1236 struct iovec iov[], unsigned int iov_size,
1237 unsigned int *out_num, unsigned int *in_num,
1238 struct vhost_log *log, unsigned int *log_num,
1239 struct vring_desc *indirect)
1240 {
1241 struct vring_desc desc;
1242 unsigned int i = 0, count, found = 0;
1243 u32 len = vhost32_to_cpu(vq, indirect->len);
1244 struct iov_iter from;
1245 int ret;
1246
1247 /* Sanity check */
1248 if (unlikely(len % sizeof desc)) {
1249 vq_err(vq, "Invalid length in indirect descriptor: "
1250 "len 0x%llx not multiple of 0x%zx\n",
1251 (unsigned long long)len,
1252 sizeof desc);
1253 return -EINVAL;
1254 }
1255
1256 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1257 UIO_MAXIOV);
1258 if (unlikely(ret < 0)) {
1259 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1260 return ret;
1261 }
1262 iov_iter_init(&from, READ, vq->indirect, ret, len);
1263
1264 /* We will use the result as an address to read from, so most
1265 * architectures only need a compiler barrier here. */
1266 read_barrier_depends();
1267
1268 count = len / sizeof desc;
1269 /* Buffers are chained via a 16 bit next field, so
1270 * we can have at most 2^16 of these. */
1271 if (unlikely(count > USHRT_MAX + 1)) {
1272 vq_err(vq, "Indirect buffer length too big: %d\n",
1273 indirect->len);
1274 return -E2BIG;
1275 }
1276
1277 do {
1278 unsigned iov_count = *in_num + *out_num;
1279 if (unlikely(++found > count)) {
1280 vq_err(vq, "Loop detected: last one at %u "
1281 "indirect size %u\n",
1282 i, count);
1283 return -EINVAL;
1284 }
1285 if (unlikely(copy_from_iter(&desc, sizeof(desc), &from) !=
1286 sizeof(desc))) {
1287 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1288 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1289 return -EINVAL;
1290 }
1291 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1292 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1293 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1294 return -EINVAL;
1295 }
1296
1297 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1298 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1299 iov_size - iov_count);
1300 if (unlikely(ret < 0)) {
1301 vq_err(vq, "Translation failure %d indirect idx %d\n",
1302 ret, i);
1303 return ret;
1304 }
1305 /* If this is an input descriptor, increment that count. */
1306 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
1307 *in_num += ret;
1308 if (unlikely(log)) {
1309 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1310 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1311 ++*log_num;
1312 }
1313 } else {
1314 /* If it's an output descriptor, they're all supposed
1315 * to come before any input descriptors. */
1316 if (unlikely(*in_num)) {
1317 vq_err(vq, "Indirect descriptor "
1318 "has out after in: idx %d\n", i);
1319 return -EINVAL;
1320 }
1321 *out_num += ret;
1322 }
1323 } while ((i = next_desc(vq, &desc)) != -1);
1324 return 0;
1325 }
1326
1327 /* This looks in the virtqueue and for the first available buffer, and converts
1328 * it to an iovec for convenient access. Since descriptors consist of some
1329 * number of output then some number of input descriptors, it's actually two
1330 * iovecs, but we pack them into one and note how many of each there were.
1331 *
1332 * This function returns the descriptor number found, or vq->num (which is
1333 * never a valid descriptor number) if none was found. A negative code is
1334 * returned on error. */
1335 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1336 struct iovec iov[], unsigned int iov_size,
1337 unsigned int *out_num, unsigned int *in_num,
1338 struct vhost_log *log, unsigned int *log_num)
1339 {
1340 struct vring_desc desc;
1341 unsigned int i, head, found = 0;
1342 u16 last_avail_idx;
1343 __virtio16 avail_idx;
1344 __virtio16 ring_head;
1345 int ret;
1346
1347 /* Check it isn't doing very strange things with descriptor numbers. */
1348 last_avail_idx = vq->last_avail_idx;
1349 if (unlikely(__get_user(avail_idx, &vq->avail->idx))) {
1350 vq_err(vq, "Failed to access avail idx at %p\n",
1351 &vq->avail->idx);
1352 return -EFAULT;
1353 }
1354 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1355
1356 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1357 vq_err(vq, "Guest moved used index from %u to %u",
1358 last_avail_idx, vq->avail_idx);
1359 return -EFAULT;
1360 }
1361
1362 /* If there's nothing new since last we looked, return invalid. */
1363 if (vq->avail_idx == last_avail_idx)
1364 return vq->num;
1365
1366 /* Only get avail ring entries after they have been exposed by guest. */
1367 smp_rmb();
1368
1369 /* Grab the next descriptor number they're advertising, and increment
1370 * the index we've seen. */
1371 if (unlikely(__get_user(ring_head,
1372 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
1373 vq_err(vq, "Failed to read head: idx %d address %p\n",
1374 last_avail_idx,
1375 &vq->avail->ring[last_avail_idx % vq->num]);
1376 return -EFAULT;
1377 }
1378
1379 head = vhost16_to_cpu(vq, ring_head);
1380
1381 /* If their number is silly, that's an error. */
1382 if (unlikely(head >= vq->num)) {
1383 vq_err(vq, "Guest says index %u > %u is available",
1384 head, vq->num);
1385 return -EINVAL;
1386 }
1387
1388 /* When we start there are none of either input nor output. */
1389 *out_num = *in_num = 0;
1390 if (unlikely(log))
1391 *log_num = 0;
1392
1393 i = head;
1394 do {
1395 unsigned iov_count = *in_num + *out_num;
1396 if (unlikely(i >= vq->num)) {
1397 vq_err(vq, "Desc index is %u > %u, head = %u",
1398 i, vq->num, head);
1399 return -EINVAL;
1400 }
1401 if (unlikely(++found > vq->num)) {
1402 vq_err(vq, "Loop detected: last one at %u "
1403 "vq size %u head %u\n",
1404 i, vq->num, head);
1405 return -EINVAL;
1406 }
1407 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1408 if (unlikely(ret)) {
1409 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1410 i, vq->desc + i);
1411 return -EFAULT;
1412 }
1413 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
1414 ret = get_indirect(vq, iov, iov_size,
1415 out_num, in_num,
1416 log, log_num, &desc);
1417 if (unlikely(ret < 0)) {
1418 vq_err(vq, "Failure detected "
1419 "in indirect descriptor at idx %d\n", i);
1420 return ret;
1421 }
1422 continue;
1423 }
1424
1425 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1426 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1427 iov_size - iov_count);
1428 if (unlikely(ret < 0)) {
1429 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1430 ret, i);
1431 return ret;
1432 }
1433 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
1434 /* If this is an input descriptor,
1435 * increment that count. */
1436 *in_num += ret;
1437 if (unlikely(log)) {
1438 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1439 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1440 ++*log_num;
1441 }
1442 } else {
1443 /* If it's an output descriptor, they're all supposed
1444 * to come before any input descriptors. */
1445 if (unlikely(*in_num)) {
1446 vq_err(vq, "Descriptor has out after in: "
1447 "idx %d\n", i);
1448 return -EINVAL;
1449 }
1450 *out_num += ret;
1451 }
1452 } while ((i = next_desc(vq, &desc)) != -1);
1453
1454 /* On success, increment avail index. */
1455 vq->last_avail_idx++;
1456
1457 /* Assume notifications from guest are disabled at this point,
1458 * if they aren't we would need to update avail_event index. */
1459 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1460 return head;
1461 }
1462 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
1463
1464 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1465 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1466 {
1467 vq->last_avail_idx -= n;
1468 }
1469 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
1470
1471 /* After we've used one of their buffers, we tell them about it. We'll then
1472 * want to notify the guest, using eventfd. */
1473 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1474 {
1475 struct vring_used_elem heads = {
1476 cpu_to_vhost32(vq, head),
1477 cpu_to_vhost32(vq, len)
1478 };
1479
1480 return vhost_add_used_n(vq, &heads, 1);
1481 }
1482 EXPORT_SYMBOL_GPL(vhost_add_used);
1483
1484 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1485 struct vring_used_elem *heads,
1486 unsigned count)
1487 {
1488 struct vring_used_elem __user *used;
1489 u16 old, new;
1490 int start;
1491
1492 start = vq->last_used_idx & (vq->num - 1);
1493 used = vq->used->ring + start;
1494 if (count == 1) {
1495 if (__put_user(heads[0].id, &used->id)) {
1496 vq_err(vq, "Failed to write used id");
1497 return -EFAULT;
1498 }
1499 if (__put_user(heads[0].len, &used->len)) {
1500 vq_err(vq, "Failed to write used len");
1501 return -EFAULT;
1502 }
1503 } else if (__copy_to_user(used, heads, count * sizeof *used)) {
1504 vq_err(vq, "Failed to write used");
1505 return -EFAULT;
1506 }
1507 if (unlikely(vq->log_used)) {
1508 /* Make sure data is seen before log. */
1509 smp_wmb();
1510 /* Log used ring entry write. */
1511 log_write(vq->log_base,
1512 vq->log_addr +
1513 ((void __user *)used - (void __user *)vq->used),
1514 count * sizeof *used);
1515 }
1516 old = vq->last_used_idx;
1517 new = (vq->last_used_idx += count);
1518 /* If the driver never bothers to signal in a very long while,
1519 * used index might wrap around. If that happens, invalidate
1520 * signalled_used index we stored. TODO: make sure driver
1521 * signals at least once in 2^16 and remove this. */
1522 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1523 vq->signalled_used_valid = false;
1524 return 0;
1525 }
1526
1527 /* After we've used one of their buffers, we tell them about it. We'll then
1528 * want to notify the guest, using eventfd. */
1529 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1530 unsigned count)
1531 {
1532 int start, n, r;
1533
1534 start = vq->last_used_idx & (vq->num - 1);
1535 n = vq->num - start;
1536 if (n < count) {
1537 r = __vhost_add_used_n(vq, heads, n);
1538 if (r < 0)
1539 return r;
1540 heads += n;
1541 count -= n;
1542 }
1543 r = __vhost_add_used_n(vq, heads, count);
1544
1545 /* Make sure buffer is written before we update index. */
1546 smp_wmb();
1547 if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) {
1548 vq_err(vq, "Failed to increment used idx");
1549 return -EFAULT;
1550 }
1551 if (unlikely(vq->log_used)) {
1552 /* Log used index update. */
1553 log_write(vq->log_base,
1554 vq->log_addr + offsetof(struct vring_used, idx),
1555 sizeof vq->used->idx);
1556 if (vq->log_ctx)
1557 eventfd_signal(vq->log_ctx, 1);
1558 }
1559 return r;
1560 }
1561 EXPORT_SYMBOL_GPL(vhost_add_used_n);
1562
1563 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1564 {
1565 __u16 old, new;
1566 __virtio16 event;
1567 bool v;
1568 /* Flush out used index updates. This is paired
1569 * with the barrier that the Guest executes when enabling
1570 * interrupts. */
1571 smp_mb();
1572
1573 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1574 unlikely(vq->avail_idx == vq->last_avail_idx))
1575 return true;
1576
1577 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1578 __virtio16 flags;
1579 if (__get_user(flags, &vq->avail->flags)) {
1580 vq_err(vq, "Failed to get flags");
1581 return true;
1582 }
1583 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
1584 }
1585 old = vq->signalled_used;
1586 v = vq->signalled_used_valid;
1587 new = vq->signalled_used = vq->last_used_idx;
1588 vq->signalled_used_valid = true;
1589
1590 if (unlikely(!v))
1591 return true;
1592
1593 if (__get_user(event, vhost_used_event(vq))) {
1594 vq_err(vq, "Failed to get used event idx");
1595 return true;
1596 }
1597 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
1598 }
1599
1600 /* This actually signals the guest, using eventfd. */
1601 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1602 {
1603 /* Signal the Guest tell them we used something up. */
1604 if (vq->call_ctx && vhost_notify(dev, vq))
1605 eventfd_signal(vq->call_ctx, 1);
1606 }
1607 EXPORT_SYMBOL_GPL(vhost_signal);
1608
1609 /* And here's the combo meal deal. Supersize me! */
1610 void vhost_add_used_and_signal(struct vhost_dev *dev,
1611 struct vhost_virtqueue *vq,
1612 unsigned int head, int len)
1613 {
1614 vhost_add_used(vq, head, len);
1615 vhost_signal(dev, vq);
1616 }
1617 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
1618
1619 /* multi-buffer version of vhost_add_used_and_signal */
1620 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1621 struct vhost_virtqueue *vq,
1622 struct vring_used_elem *heads, unsigned count)
1623 {
1624 vhost_add_used_n(vq, heads, count);
1625 vhost_signal(dev, vq);
1626 }
1627 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
1628
1629 /* OK, now we need to know about added descriptors. */
1630 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1631 {
1632 __virtio16 avail_idx;
1633 int r;
1634
1635 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1636 return false;
1637 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1638 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1639 r = vhost_update_used_flags(vq);
1640 if (r) {
1641 vq_err(vq, "Failed to enable notification at %p: %d\n",
1642 &vq->used->flags, r);
1643 return false;
1644 }
1645 } else {
1646 r = vhost_update_avail_event(vq, vq->avail_idx);
1647 if (r) {
1648 vq_err(vq, "Failed to update avail event index at %p: %d\n",
1649 vhost_avail_event(vq), r);
1650 return false;
1651 }
1652 }
1653 /* They could have slipped one in as we were doing that: make
1654 * sure it's written, then check again. */
1655 smp_mb();
1656 r = __get_user(avail_idx, &vq->avail->idx);
1657 if (r) {
1658 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1659 &vq->avail->idx, r);
1660 return false;
1661 }
1662
1663 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
1664 }
1665 EXPORT_SYMBOL_GPL(vhost_enable_notify);
1666
1667 /* We don't need to be notified again. */
1668 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1669 {
1670 int r;
1671
1672 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1673 return;
1674 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1675 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1676 r = vhost_update_used_flags(vq);
1677 if (r)
1678 vq_err(vq, "Failed to enable notification at %p: %d\n",
1679 &vq->used->flags, r);
1680 }
1681 }
1682 EXPORT_SYMBOL_GPL(vhost_disable_notify);
1683
1684 static int __init vhost_init(void)
1685 {
1686 return 0;
1687 }
1688
1689 static void __exit vhost_exit(void)
1690 {
1691 }
1692
1693 module_init(vhost_init);
1694 module_exit(vhost_exit);
1695
1696 MODULE_VERSION("0.0.1");
1697 MODULE_LICENSE("GPL v2");
1698 MODULE_AUTHOR("Michael S. Tsirkin");
1699 MODULE_DESCRIPTION("Host kernel accelerator for virtio");
Linux kernel - Deliverables
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