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spi: omap2-mcspi: Fix the redifine warning
[GitHub/mt8127/android_kernel_alcatel_ttab.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/virtio_net.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/rcupdate.h>
22 #include <linux/poll.h>
23 #include <linux/file.h>
24 #include <linux/highmem.h>
25 #include <linux/slab.h>
26 #include <linux/kthread.h>
27 #include <linux/cgroup.h>
28
29 #include <linux/net.h>
30 #include <linux/if_packet.h>
31 #include <linux/if_arp.h>
32
33 #include "vhost.h"
34
35 enum {
36 VHOST_MEMORY_MAX_NREGIONS = 64,
37 VHOST_MEMORY_F_LOG = 0x1,
38 };
39
40 static unsigned vhost_zcopy_mask __read_mostly;
41
42 #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
43 #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
44
45 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
46 poll_table *pt)
47 {
48 struct vhost_poll *poll;
49
50 poll = container_of(pt, struct vhost_poll, table);
51 poll->wqh = wqh;
52 add_wait_queue(wqh, &poll->wait);
53 }
54
55 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
56 void *key)
57 {
58 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
59
60 if (!((unsigned long)key & poll->mask))
61 return 0;
62
63 vhost_poll_queue(poll);
64 return 0;
65 }
66
67 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
68 {
69 INIT_LIST_HEAD(&work->node);
70 work->fn = fn;
71 init_waitqueue_head(&work->done);
72 work->flushing = 0;
73 work->queue_seq = work->done_seq = 0;
74 }
75
76 /* Init poll structure */
77 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
78 unsigned long mask, struct vhost_dev *dev)
79 {
80 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
81 init_poll_funcptr(&poll->table, vhost_poll_func);
82 poll->mask = mask;
83 poll->dev = dev;
84
85 vhost_work_init(&poll->work, fn);
86 }
87
88 /* Start polling a file. We add ourselves to file's wait queue. The caller must
89 * keep a reference to a file until after vhost_poll_stop is called. */
90 void vhost_poll_start(struct vhost_poll *poll, struct file *file)
91 {
92 unsigned long mask;
93
94 mask = file->f_op->poll(file, &poll->table);
95 if (mask)
96 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
97 }
98
99 /* Stop polling a file. After this function returns, it becomes safe to drop the
100 * file reference. You must also flush afterwards. */
101 void vhost_poll_stop(struct vhost_poll *poll)
102 {
103 remove_wait_queue(poll->wqh, &poll->wait);
104 }
105
106 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
107 unsigned seq)
108 {
109 int left;
110
111 spin_lock_irq(&dev->work_lock);
112 left = seq - work->done_seq;
113 spin_unlock_irq(&dev->work_lock);
114 return left <= 0;
115 }
116
117 static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
118 {
119 unsigned seq;
120 int flushing;
121
122 spin_lock_irq(&dev->work_lock);
123 seq = work->queue_seq;
124 work->flushing++;
125 spin_unlock_irq(&dev->work_lock);
126 wait_event(work->done, vhost_work_seq_done(dev, work, seq));
127 spin_lock_irq(&dev->work_lock);
128 flushing = --work->flushing;
129 spin_unlock_irq(&dev->work_lock);
130 BUG_ON(flushing < 0);
131 }
132
133 /* Flush any work that has been scheduled. When calling this, don't hold any
134 * locks that are also used by the callback. */
135 void vhost_poll_flush(struct vhost_poll *poll)
136 {
137 vhost_work_flush(poll->dev, &poll->work);
138 }
139
140 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
141 {
142 unsigned long flags;
143
144 spin_lock_irqsave(&dev->work_lock, flags);
145 if (list_empty(&work->node)) {
146 list_add_tail(&work->node, &dev->work_list);
147 work->queue_seq++;
148 wake_up_process(dev->worker);
149 }
150 spin_unlock_irqrestore(&dev->work_lock, flags);
151 }
152
153 void vhost_poll_queue(struct vhost_poll *poll)
154 {
155 vhost_work_queue(poll->dev, &poll->work);
156 }
157
158 static void vhost_vq_reset(struct vhost_dev *dev,
159 struct vhost_virtqueue *vq)
160 {
161 vq->num = 1;
162 vq->desc = NULL;
163 vq->avail = NULL;
164 vq->used = NULL;
165 vq->last_avail_idx = 0;
166 vq->avail_idx = 0;
167 vq->last_used_idx = 0;
168 vq->signalled_used = 0;
169 vq->signalled_used_valid = false;
170 vq->used_flags = 0;
171 vq->log_used = false;
172 vq->log_addr = -1ull;
173 vq->vhost_hlen = 0;
174 vq->sock_hlen = 0;
175 vq->private_data = NULL;
176 vq->log_base = NULL;
177 vq->error_ctx = NULL;
178 vq->error = NULL;
179 vq->kick = NULL;
180 vq->call_ctx = NULL;
181 vq->call = NULL;
182 vq->log_ctx = NULL;
183 vq->upend_idx = 0;
184 vq->done_idx = 0;
185 vq->ubufs = NULL;
186 }
187
188 static int vhost_worker(void *data)
189 {
190 struct vhost_dev *dev = data;
191 struct vhost_work *work = NULL;
192 unsigned uninitialized_var(seq);
193 mm_segment_t oldfs = get_fs();
194
195 set_fs(USER_DS);
196 use_mm(dev->mm);
197
198 for (;;) {
199 /* mb paired w/ kthread_stop */
200 set_current_state(TASK_INTERRUPTIBLE);
201
202 spin_lock_irq(&dev->work_lock);
203 if (work) {
204 work->done_seq = seq;
205 if (work->flushing)
206 wake_up_all(&work->done);
207 }
208
209 if (kthread_should_stop()) {
210 spin_unlock_irq(&dev->work_lock);
211 __set_current_state(TASK_RUNNING);
212 break;
213 }
214 if (!list_empty(&dev->work_list)) {
215 work = list_first_entry(&dev->work_list,
216 struct vhost_work, node);
217 list_del_init(&work->node);
218 seq = work->queue_seq;
219 } else
220 work = NULL;
221 spin_unlock_irq(&dev->work_lock);
222
223 if (work) {
224 __set_current_state(TASK_RUNNING);
225 work->fn(work);
226 if (need_resched())
227 schedule();
228 } else
229 schedule();
230
231 }
232 unuse_mm(dev->mm);
233 set_fs(oldfs);
234 return 0;
235 }
236
237 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
238 {
239 kfree(vq->indirect);
240 vq->indirect = NULL;
241 kfree(vq->log);
242 vq->log = NULL;
243 kfree(vq->heads);
244 vq->heads = NULL;
245 kfree(vq->ubuf_info);
246 vq->ubuf_info = NULL;
247 }
248
249 void vhost_enable_zcopy(int vq)
250 {
251 vhost_zcopy_mask |= 0x1 << vq;
252 }
253
254 /* Helper to allocate iovec buffers for all vqs. */
255 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
256 {
257 int i;
258 bool zcopy;
259
260 for (i = 0; i < dev->nvqs; ++i) {
261 dev->vqs[i].indirect = kmalloc(sizeof *dev->vqs[i].indirect *
262 UIO_MAXIOV, GFP_KERNEL);
263 dev->vqs[i].log = kmalloc(sizeof *dev->vqs[i].log * UIO_MAXIOV,
264 GFP_KERNEL);
265 dev->vqs[i].heads = kmalloc(sizeof *dev->vqs[i].heads *
266 UIO_MAXIOV, GFP_KERNEL);
267 zcopy = vhost_zcopy_mask & (0x1 << i);
268 if (zcopy)
269 dev->vqs[i].ubuf_info =
270 kmalloc(sizeof *dev->vqs[i].ubuf_info *
271 UIO_MAXIOV, GFP_KERNEL);
272 if (!dev->vqs[i].indirect || !dev->vqs[i].log ||
273 !dev->vqs[i].heads ||
274 (zcopy && !dev->vqs[i].ubuf_info))
275 goto err_nomem;
276 }
277 return 0;
278
279 err_nomem:
280 for (; i >= 0; --i)
281 vhost_vq_free_iovecs(&dev->vqs[i]);
282 return -ENOMEM;
283 }
284
285 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
286 {
287 int i;
288
289 for (i = 0; i < dev->nvqs; ++i)
290 vhost_vq_free_iovecs(&dev->vqs[i]);
291 }
292
293 long vhost_dev_init(struct vhost_dev *dev,
294 struct vhost_virtqueue *vqs, int nvqs)
295 {
296 int i;
297
298 dev->vqs = vqs;
299 dev->nvqs = nvqs;
300 mutex_init(&dev->mutex);
301 dev->log_ctx = NULL;
302 dev->log_file = NULL;
303 dev->memory = NULL;
304 dev->mm = NULL;
305 spin_lock_init(&dev->work_lock);
306 INIT_LIST_HEAD(&dev->work_list);
307 dev->worker = NULL;
308
309 for (i = 0; i < dev->nvqs; ++i) {
310 dev->vqs[i].log = NULL;
311 dev->vqs[i].indirect = NULL;
312 dev->vqs[i].heads = NULL;
313 dev->vqs[i].ubuf_info = NULL;
314 dev->vqs[i].dev = dev;
315 mutex_init(&dev->vqs[i].mutex);
316 vhost_vq_reset(dev, dev->vqs + i);
317 if (dev->vqs[i].handle_kick)
318 vhost_poll_init(&dev->vqs[i].poll,
319 dev->vqs[i].handle_kick, POLLIN, dev);
320 }
321
322 return 0;
323 }
324
325 /* Caller should have device mutex */
326 long vhost_dev_check_owner(struct vhost_dev *dev)
327 {
328 /* Are you the owner? If not, I don't think you mean to do that */
329 return dev->mm == current->mm ? 0 : -EPERM;
330 }
331
332 struct vhost_attach_cgroups_struct {
333 struct vhost_work work;
334 struct task_struct *owner;
335 int ret;
336 };
337
338 static void vhost_attach_cgroups_work(struct vhost_work *work)
339 {
340 struct vhost_attach_cgroups_struct *s;
341
342 s = container_of(work, struct vhost_attach_cgroups_struct, work);
343 s->ret = cgroup_attach_task_all(s->owner, current);
344 }
345
346 static int vhost_attach_cgroups(struct vhost_dev *dev)
347 {
348 struct vhost_attach_cgroups_struct attach;
349
350 attach.owner = current;
351 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
352 vhost_work_queue(dev, &attach.work);
353 vhost_work_flush(dev, &attach.work);
354 return attach.ret;
355 }
356
357 /* Caller should have device mutex */
358 static long vhost_dev_set_owner(struct vhost_dev *dev)
359 {
360 struct task_struct *worker;
361 int err;
362
363 /* Is there an owner already? */
364 if (dev->mm) {
365 err = -EBUSY;
366 goto err_mm;
367 }
368
369 /* No owner, become one */
370 dev->mm = get_task_mm(current);
371 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
372 if (IS_ERR(worker)) {
373 err = PTR_ERR(worker);
374 goto err_worker;
375 }
376
377 dev->worker = worker;
378 wake_up_process(worker); /* avoid contributing to loadavg */
379
380 err = vhost_attach_cgroups(dev);
381 if (err)
382 goto err_cgroup;
383
384 err = vhost_dev_alloc_iovecs(dev);
385 if (err)
386 goto err_cgroup;
387
388 return 0;
389 err_cgroup:
390 kthread_stop(worker);
391 dev->worker = NULL;
392 err_worker:
393 if (dev->mm)
394 mmput(dev->mm);
395 dev->mm = NULL;
396 err_mm:
397 return err;
398 }
399
400 /* Caller should have device mutex */
401 long vhost_dev_reset_owner(struct vhost_dev *dev)
402 {
403 struct vhost_memory *memory;
404
405 /* Restore memory to default empty mapping. */
406 memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
407 if (!memory)
408 return -ENOMEM;
409
410 vhost_dev_cleanup(dev, true);
411
412 memory->nregions = 0;
413 RCU_INIT_POINTER(dev->memory, memory);
414 return 0;
415 }
416
417 /* In case of DMA done not in order in lower device driver for some reason.
418 * upend_idx is used to track end of used idx, done_idx is used to track head
419 * of used idx. Once lower device DMA done contiguously, we will signal KVM
420 * guest used idx.
421 */
422 int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq)
423 {
424 int i;
425 int j = 0;
426
427 for (i = vq->done_idx; i != vq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
428 if ((vq->heads[i].len == VHOST_DMA_DONE_LEN)) {
429 vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
430 vhost_add_used_and_signal(vq->dev, vq,
431 vq->heads[i].id, 0);
432 ++j;
433 } else
434 break;
435 }
436 if (j)
437 vq->done_idx = i;
438 return j;
439 }
440
441 /* Caller should have device mutex if and only if locked is set */
442 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
443 {
444 int i;
445
446 for (i = 0; i < dev->nvqs; ++i) {
447 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) {
448 vhost_poll_stop(&dev->vqs[i].poll);
449 vhost_poll_flush(&dev->vqs[i].poll);
450 }
451 /* Wait for all lower device DMAs done. */
452 if (dev->vqs[i].ubufs)
453 vhost_ubuf_put_and_wait(dev->vqs[i].ubufs);
454
455 /* Signal guest as appropriate. */
456 vhost_zerocopy_signal_used(&dev->vqs[i]);
457
458 if (dev->vqs[i].error_ctx)
459 eventfd_ctx_put(dev->vqs[i].error_ctx);
460 if (dev->vqs[i].error)
461 fput(dev->vqs[i].error);
462 if (dev->vqs[i].kick)
463 fput(dev->vqs[i].kick);
464 if (dev->vqs[i].call_ctx)
465 eventfd_ctx_put(dev->vqs[i].call_ctx);
466 if (dev->vqs[i].call)
467 fput(dev->vqs[i].call);
468 vhost_vq_reset(dev, dev->vqs + i);
469 }
470 vhost_dev_free_iovecs(dev);
471 if (dev->log_ctx)
472 eventfd_ctx_put(dev->log_ctx);
473 dev->log_ctx = NULL;
474 if (dev->log_file)
475 fput(dev->log_file);
476 dev->log_file = NULL;
477 /* No one will access memory at this point */
478 kfree(rcu_dereference_protected(dev->memory,
479 locked ==
480 lockdep_is_held(&dev->mutex)));
481 RCU_INIT_POINTER(dev->memory, NULL);
482 WARN_ON(!list_empty(&dev->work_list));
483 if (dev->worker) {
484 kthread_stop(dev->worker);
485 dev->worker = NULL;
486 }
487 if (dev->mm)
488 mmput(dev->mm);
489 dev->mm = NULL;
490 }
491
492 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
493 {
494 u64 a = addr / VHOST_PAGE_SIZE / 8;
495
496 /* Make sure 64 bit math will not overflow. */
497 if (a > ULONG_MAX - (unsigned long)log_base ||
498 a + (unsigned long)log_base > ULONG_MAX)
499 return 0;
500
501 return access_ok(VERIFY_WRITE, log_base + a,
502 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
503 }
504
505 /* Caller should have vq mutex and device mutex. */
506 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
507 int log_all)
508 {
509 int i;
510
511 if (!mem)
512 return 0;
513
514 for (i = 0; i < mem->nregions; ++i) {
515 struct vhost_memory_region *m = mem->regions + i;
516 unsigned long a = m->userspace_addr;
517 if (m->memory_size > ULONG_MAX)
518 return 0;
519 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
520 m->memory_size))
521 return 0;
522 else if (log_all && !log_access_ok(log_base,
523 m->guest_phys_addr,
524 m->memory_size))
525 return 0;
526 }
527 return 1;
528 }
529
530 /* Can we switch to this memory table? */
531 /* Caller should have device mutex but not vq mutex */
532 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
533 int log_all)
534 {
535 int i;
536
537 for (i = 0; i < d->nvqs; ++i) {
538 int ok;
539 mutex_lock(&d->vqs[i].mutex);
540 /* If ring is inactive, will check when it's enabled. */
541 if (d->vqs[i].private_data)
542 ok = vq_memory_access_ok(d->vqs[i].log_base, mem,
543 log_all);
544 else
545 ok = 1;
546 mutex_unlock(&d->vqs[i].mutex);
547 if (!ok)
548 return 0;
549 }
550 return 1;
551 }
552
553 static int vq_access_ok(struct vhost_dev *d, unsigned int num,
554 struct vring_desc __user *desc,
555 struct vring_avail __user *avail,
556 struct vring_used __user *used)
557 {
558 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
559 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
560 access_ok(VERIFY_READ, avail,
561 sizeof *avail + num * sizeof *avail->ring + s) &&
562 access_ok(VERIFY_WRITE, used,
563 sizeof *used + num * sizeof *used->ring + s);
564 }
565
566 /* Can we log writes? */
567 /* Caller should have device mutex but not vq mutex */
568 int vhost_log_access_ok(struct vhost_dev *dev)
569 {
570 struct vhost_memory *mp;
571
572 mp = rcu_dereference_protected(dev->memory,
573 lockdep_is_held(&dev->mutex));
574 return memory_access_ok(dev, mp, 1);
575 }
576
577 /* Verify access for write logging. */
578 /* Caller should have vq mutex and device mutex */
579 static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
580 void __user *log_base)
581 {
582 struct vhost_memory *mp;
583 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
584
585 mp = rcu_dereference_protected(vq->dev->memory,
586 lockdep_is_held(&vq->mutex));
587 return vq_memory_access_ok(log_base, mp,
588 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
589 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
590 sizeof *vq->used +
591 vq->num * sizeof *vq->used->ring + s));
592 }
593
594 /* Can we start vq? */
595 /* Caller should have vq mutex and device mutex */
596 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
597 {
598 return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
599 vq_log_access_ok(vq->dev, vq, vq->log_base);
600 }
601
602 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
603 {
604 struct vhost_memory mem, *newmem, *oldmem;
605 unsigned long size = offsetof(struct vhost_memory, regions);
606
607 if (copy_from_user(&mem, m, size))
608 return -EFAULT;
609 if (mem.padding)
610 return -EOPNOTSUPP;
611 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
612 return -E2BIG;
613 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL);
614 if (!newmem)
615 return -ENOMEM;
616
617 memcpy(newmem, &mem, size);
618 if (copy_from_user(newmem->regions, m->regions,
619 mem.nregions * sizeof *m->regions)) {
620 kfree(newmem);
621 return -EFAULT;
622 }
623
624 if (!memory_access_ok(d, newmem,
625 vhost_has_feature(d, VHOST_F_LOG_ALL))) {
626 kfree(newmem);
627 return -EFAULT;
628 }
629 oldmem = rcu_dereference_protected(d->memory,
630 lockdep_is_held(&d->mutex));
631 rcu_assign_pointer(d->memory, newmem);
632 synchronize_rcu();
633 kfree(oldmem);
634 return 0;
635 }
636
637 static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
638 {
639 struct file *eventfp, *filep = NULL;
640 bool pollstart = false, pollstop = false;
641 struct eventfd_ctx *ctx = NULL;
642 u32 __user *idxp = argp;
643 struct vhost_virtqueue *vq;
644 struct vhost_vring_state s;
645 struct vhost_vring_file f;
646 struct vhost_vring_addr a;
647 u32 idx;
648 long r;
649
650 r = get_user(idx, idxp);
651 if (r < 0)
652 return r;
653 if (idx >= d->nvqs)
654 return -ENOBUFS;
655
656 vq = d->vqs + idx;
657
658 mutex_lock(&vq->mutex);
659
660 switch (ioctl) {
661 case VHOST_SET_VRING_NUM:
662 /* Resizing ring with an active backend?
663 * You don't want to do that. */
664 if (vq->private_data) {
665 r = -EBUSY;
666 break;
667 }
668 if (copy_from_user(&s, argp, sizeof s)) {
669 r = -EFAULT;
670 break;
671 }
672 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
673 r = -EINVAL;
674 break;
675 }
676 vq->num = s.num;
677 break;
678 case VHOST_SET_VRING_BASE:
679 /* Moving base with an active backend?
680 * You don't want to do that. */
681 if (vq->private_data) {
682 r = -EBUSY;
683 break;
684 }
685 if (copy_from_user(&s, argp, sizeof s)) {
686 r = -EFAULT;
687 break;
688 }
689 if (s.num > 0xffff) {
690 r = -EINVAL;
691 break;
692 }
693 vq->last_avail_idx = s.num;
694 /* Forget the cached index value. */
695 vq->avail_idx = vq->last_avail_idx;
696 break;
697 case VHOST_GET_VRING_BASE:
698 s.index = idx;
699 s.num = vq->last_avail_idx;
700 if (copy_to_user(argp, &s, sizeof s))
701 r = -EFAULT;
702 break;
703 case VHOST_SET_VRING_ADDR:
704 if (copy_from_user(&a, argp, sizeof a)) {
705 r = -EFAULT;
706 break;
707 }
708 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
709 r = -EOPNOTSUPP;
710 break;
711 }
712 /* For 32bit, verify that the top 32bits of the user
713 data are set to zero. */
714 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
715 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
716 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
717 r = -EFAULT;
718 break;
719 }
720 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
721 (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
722 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
723 r = -EINVAL;
724 break;
725 }
726
727 /* We only verify access here if backend is configured.
728 * If it is not, we don't as size might not have been setup.
729 * We will verify when backend is configured. */
730 if (vq->private_data) {
731 if (!vq_access_ok(d, vq->num,
732 (void __user *)(unsigned long)a.desc_user_addr,
733 (void __user *)(unsigned long)a.avail_user_addr,
734 (void __user *)(unsigned long)a.used_user_addr)) {
735 r = -EINVAL;
736 break;
737 }
738
739 /* Also validate log access for used ring if enabled. */
740 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
741 !log_access_ok(vq->log_base, a.log_guest_addr,
742 sizeof *vq->used +
743 vq->num * sizeof *vq->used->ring)) {
744 r = -EINVAL;
745 break;
746 }
747 }
748
749 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
750 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
751 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
752 vq->log_addr = a.log_guest_addr;
753 vq->used = (void __user *)(unsigned long)a.used_user_addr;
754 break;
755 case VHOST_SET_VRING_KICK:
756 if (copy_from_user(&f, argp, sizeof f)) {
757 r = -EFAULT;
758 break;
759 }
760 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
761 if (IS_ERR(eventfp)) {
762 r = PTR_ERR(eventfp);
763 break;
764 }
765 if (eventfp != vq->kick) {
766 pollstop = (filep = vq->kick) != NULL;
767 pollstart = (vq->kick = eventfp) != NULL;
768 } else
769 filep = eventfp;
770 break;
771 case VHOST_SET_VRING_CALL:
772 if (copy_from_user(&f, argp, sizeof f)) {
773 r = -EFAULT;
774 break;
775 }
776 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
777 if (IS_ERR(eventfp)) {
778 r = PTR_ERR(eventfp);
779 break;
780 }
781 if (eventfp != vq->call) {
782 filep = vq->call;
783 ctx = vq->call_ctx;
784 vq->call = eventfp;
785 vq->call_ctx = eventfp ?
786 eventfd_ctx_fileget(eventfp) : NULL;
787 } else
788 filep = eventfp;
789 break;
790 case VHOST_SET_VRING_ERR:
791 if (copy_from_user(&f, argp, sizeof f)) {
792 r = -EFAULT;
793 break;
794 }
795 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
796 if (IS_ERR(eventfp)) {
797 r = PTR_ERR(eventfp);
798 break;
799 }
800 if (eventfp != vq->error) {
801 filep = vq->error;
802 vq->error = eventfp;
803 ctx = vq->error_ctx;
804 vq->error_ctx = eventfp ?
805 eventfd_ctx_fileget(eventfp) : NULL;
806 } else
807 filep = eventfp;
808 break;
809 default:
810 r = -ENOIOCTLCMD;
811 }
812
813 if (pollstop && vq->handle_kick)
814 vhost_poll_stop(&vq->poll);
815
816 if (ctx)
817 eventfd_ctx_put(ctx);
818 if (filep)
819 fput(filep);
820
821 if (pollstart && vq->handle_kick)
822 vhost_poll_start(&vq->poll, vq->kick);
823
824 mutex_unlock(&vq->mutex);
825
826 if (pollstop && vq->handle_kick)
827 vhost_poll_flush(&vq->poll);
828 return r;
829 }
830
831 /* Caller must have device mutex */
832 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
833 {
834 void __user *argp = (void __user *)arg;
835 struct file *eventfp, *filep = NULL;
836 struct eventfd_ctx *ctx = NULL;
837 u64 p;
838 long r;
839 int i, fd;
840
841 /* If you are not the owner, you can become one */
842 if (ioctl == VHOST_SET_OWNER) {
843 r = vhost_dev_set_owner(d);
844 goto done;
845 }
846
847 /* You must be the owner to do anything else */
848 r = vhost_dev_check_owner(d);
849 if (r)
850 goto done;
851
852 switch (ioctl) {
853 case VHOST_SET_MEM_TABLE:
854 r = vhost_set_memory(d, argp);
855 break;
856 case VHOST_SET_LOG_BASE:
857 if (copy_from_user(&p, argp, sizeof p)) {
858 r = -EFAULT;
859 break;
860 }
861 if ((u64)(unsigned long)p != p) {
862 r = -EFAULT;
863 break;
864 }
865 for (i = 0; i < d->nvqs; ++i) {
866 struct vhost_virtqueue *vq;
867 void __user *base = (void __user *)(unsigned long)p;
868 vq = d->vqs + i;
869 mutex_lock(&vq->mutex);
870 /* If ring is inactive, will check when it's enabled. */
871 if (vq->private_data && !vq_log_access_ok(d, vq, base))
872 r = -EFAULT;
873 else
874 vq->log_base = base;
875 mutex_unlock(&vq->mutex);
876 }
877 break;
878 case VHOST_SET_LOG_FD:
879 r = get_user(fd, (int __user *)argp);
880 if (r < 0)
881 break;
882 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
883 if (IS_ERR(eventfp)) {
884 r = PTR_ERR(eventfp);
885 break;
886 }
887 if (eventfp != d->log_file) {
888 filep = d->log_file;
889 ctx = d->log_ctx;
890 d->log_ctx = eventfp ?
891 eventfd_ctx_fileget(eventfp) : NULL;
892 } else
893 filep = eventfp;
894 for (i = 0; i < d->nvqs; ++i) {
895 mutex_lock(&d->vqs[i].mutex);
896 d->vqs[i].log_ctx = d->log_ctx;
897 mutex_unlock(&d->vqs[i].mutex);
898 }
899 if (ctx)
900 eventfd_ctx_put(ctx);
901 if (filep)
902 fput(filep);
903 break;
904 default:
905 r = vhost_set_vring(d, ioctl, argp);
906 break;
907 }
908 done:
909 return r;
910 }
911
912 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
913 __u64 addr, __u32 len)
914 {
915 struct vhost_memory_region *reg;
916 int i;
917
918 /* linear search is not brilliant, but we really have on the order of 6
919 * regions in practice */
920 for (i = 0; i < mem->nregions; ++i) {
921 reg = mem->regions + i;
922 if (reg->guest_phys_addr <= addr &&
923 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
924 return reg;
925 }
926 return NULL;
927 }
928
929 /* TODO: This is really inefficient. We need something like get_user()
930 * (instruction directly accesses the data, with an exception table entry
931 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
932 */
933 static int set_bit_to_user(int nr, void __user *addr)
934 {
935 unsigned long log = (unsigned long)addr;
936 struct page *page;
937 void *base;
938 int bit = nr + (log % PAGE_SIZE) * 8;
939 int r;
940
941 r = get_user_pages_fast(log, 1, 1, &page);
942 if (r < 0)
943 return r;
944 BUG_ON(r != 1);
945 base = kmap_atomic(page);
946 set_bit(bit, base);
947 kunmap_atomic(base);
948 set_page_dirty_lock(page);
949 put_page(page);
950 return 0;
951 }
952
953 static int log_write(void __user *log_base,
954 u64 write_address, u64 write_length)
955 {
956 u64 write_page = write_address / VHOST_PAGE_SIZE;
957 int r;
958
959 if (!write_length)
960 return 0;
961 write_length += write_address % VHOST_PAGE_SIZE;
962 for (;;) {
963 u64 base = (u64)(unsigned long)log_base;
964 u64 log = base + write_page / 8;
965 int bit = write_page % 8;
966 if ((u64)(unsigned long)log != log)
967 return -EFAULT;
968 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
969 if (r < 0)
970 return r;
971 if (write_length <= VHOST_PAGE_SIZE)
972 break;
973 write_length -= VHOST_PAGE_SIZE;
974 write_page += 1;
975 }
976 return r;
977 }
978
979 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
980 unsigned int log_num, u64 len)
981 {
982 int i, r;
983
984 /* Make sure data written is seen before log. */
985 smp_wmb();
986 for (i = 0; i < log_num; ++i) {
987 u64 l = min(log[i].len, len);
988 r = log_write(vq->log_base, log[i].addr, l);
989 if (r < 0)
990 return r;
991 len -= l;
992 if (!len) {
993 if (vq->log_ctx)
994 eventfd_signal(vq->log_ctx, 1);
995 return 0;
996 }
997 }
998 /* Length written exceeds what we have stored. This is a bug. */
999 BUG();
1000 return 0;
1001 }
1002
1003 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1004 {
1005 void __user *used;
1006 if (__put_user(vq->used_flags, &vq->used->flags) < 0)
1007 return -EFAULT;
1008 if (unlikely(vq->log_used)) {
1009 /* Make sure the flag is seen before log. */
1010 smp_wmb();
1011 /* Log used flag write. */
1012 used = &vq->used->flags;
1013 log_write(vq->log_base, vq->log_addr +
1014 (used - (void __user *)vq->used),
1015 sizeof vq->used->flags);
1016 if (vq->log_ctx)
1017 eventfd_signal(vq->log_ctx, 1);
1018 }
1019 return 0;
1020 }
1021
1022 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1023 {
1024 if (__put_user(vq->avail_idx, vhost_avail_event(vq)))
1025 return -EFAULT;
1026 if (unlikely(vq->log_used)) {
1027 void __user *used;
1028 /* Make sure the event is seen before log. */
1029 smp_wmb();
1030 /* Log avail event write */
1031 used = vhost_avail_event(vq);
1032 log_write(vq->log_base, vq->log_addr +
1033 (used - (void __user *)vq->used),
1034 sizeof *vhost_avail_event(vq));
1035 if (vq->log_ctx)
1036 eventfd_signal(vq->log_ctx, 1);
1037 }
1038 return 0;
1039 }
1040
1041 int vhost_init_used(struct vhost_virtqueue *vq)
1042 {
1043 int r;
1044 if (!vq->private_data)
1045 return 0;
1046
1047 r = vhost_update_used_flags(vq);
1048 if (r)
1049 return r;
1050 vq->signalled_used_valid = false;
1051 return get_user(vq->last_used_idx, &vq->used->idx);
1052 }
1053
1054 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
1055 struct iovec iov[], int iov_size)
1056 {
1057 const struct vhost_memory_region *reg;
1058 struct vhost_memory *mem;
1059 struct iovec *_iov;
1060 u64 s = 0;
1061 int ret = 0;
1062
1063 rcu_read_lock();
1064
1065 mem = rcu_dereference(dev->memory);
1066 while ((u64)len > s) {
1067 u64 size;
1068 if (unlikely(ret >= iov_size)) {
1069 ret = -ENOBUFS;
1070 break;
1071 }
1072 reg = find_region(mem, addr, len);
1073 if (unlikely(!reg)) {
1074 ret = -EFAULT;
1075 break;
1076 }
1077 _iov = iov + ret;
1078 size = reg->memory_size - addr + reg->guest_phys_addr;
1079 _iov->iov_len = min((u64)len, size);
1080 _iov->iov_base = (void __user *)(unsigned long)
1081 (reg->userspace_addr + addr - reg->guest_phys_addr);
1082 s += size;
1083 addr += size;
1084 ++ret;
1085 }
1086
1087 rcu_read_unlock();
1088 return ret;
1089 }
1090
1091 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1092 * function returns the next descriptor in the chain,
1093 * or -1U if we're at the end. */
1094 static unsigned next_desc(struct vring_desc *desc)
1095 {
1096 unsigned int next;
1097
1098 /* If this descriptor says it doesn't chain, we're done. */
1099 if (!(desc->flags & VRING_DESC_F_NEXT))
1100 return -1U;
1101
1102 /* Check they're not leading us off end of descriptors. */
1103 next = desc->next;
1104 /* Make sure compiler knows to grab that: we don't want it changing! */
1105 /* We will use the result as an index in an array, so most
1106 * architectures only need a compiler barrier here. */
1107 read_barrier_depends();
1108
1109 return next;
1110 }
1111
1112 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1113 struct iovec iov[], unsigned int iov_size,
1114 unsigned int *out_num, unsigned int *in_num,
1115 struct vhost_log *log, unsigned int *log_num,
1116 struct vring_desc *indirect)
1117 {
1118 struct vring_desc desc;
1119 unsigned int i = 0, count, found = 0;
1120 int ret;
1121
1122 /* Sanity check */
1123 if (unlikely(indirect->len % sizeof desc)) {
1124 vq_err(vq, "Invalid length in indirect descriptor: "
1125 "len 0x%llx not multiple of 0x%zx\n",
1126 (unsigned long long)indirect->len,
1127 sizeof desc);
1128 return -EINVAL;
1129 }
1130
1131 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect,
1132 UIO_MAXIOV);
1133 if (unlikely(ret < 0)) {
1134 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1135 return ret;
1136 }
1137
1138 /* We will use the result as an address to read from, so most
1139 * architectures only need a compiler barrier here. */
1140 read_barrier_depends();
1141
1142 count = indirect->len / sizeof desc;
1143 /* Buffers are chained via a 16 bit next field, so
1144 * we can have at most 2^16 of these. */
1145 if (unlikely(count > USHRT_MAX + 1)) {
1146 vq_err(vq, "Indirect buffer length too big: %d\n",
1147 indirect->len);
1148 return -E2BIG;
1149 }
1150
1151 do {
1152 unsigned iov_count = *in_num + *out_num;
1153 if (unlikely(++found > count)) {
1154 vq_err(vq, "Loop detected: last one at %u "
1155 "indirect size %u\n",
1156 i, count);
1157 return -EINVAL;
1158 }
1159 if (unlikely(memcpy_fromiovec((unsigned char *)&desc,
1160 vq->indirect, sizeof desc))) {
1161 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1162 i, (size_t)indirect->addr + i * sizeof desc);
1163 return -EINVAL;
1164 }
1165 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
1166 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1167 i, (size_t)indirect->addr + i * sizeof desc);
1168 return -EINVAL;
1169 }
1170
1171 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1172 iov_size - iov_count);
1173 if (unlikely(ret < 0)) {
1174 vq_err(vq, "Translation failure %d indirect idx %d\n",
1175 ret, i);
1176 return ret;
1177 }
1178 /* If this is an input descriptor, increment that count. */
1179 if (desc.flags & VRING_DESC_F_WRITE) {
1180 *in_num += ret;
1181 if (unlikely(log)) {
1182 log[*log_num].addr = desc.addr;
1183 log[*log_num].len = desc.len;
1184 ++*log_num;
1185 }
1186 } else {
1187 /* If it's an output descriptor, they're all supposed
1188 * to come before any input descriptors. */
1189 if (unlikely(*in_num)) {
1190 vq_err(vq, "Indirect descriptor "
1191 "has out after in: idx %d\n", i);
1192 return -EINVAL;
1193 }
1194 *out_num += ret;
1195 }
1196 } while ((i = next_desc(&desc)) != -1);
1197 return 0;
1198 }
1199
1200 /* This looks in the virtqueue and for the first available buffer, and converts
1201 * it to an iovec for convenient access. Since descriptors consist of some
1202 * number of output then some number of input descriptors, it's actually two
1203 * iovecs, but we pack them into one and note how many of each there were.
1204 *
1205 * This function returns the descriptor number found, or vq->num (which is
1206 * never a valid descriptor number) if none was found. A negative code is
1207 * returned on error. */
1208 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1209 struct iovec iov[], unsigned int iov_size,
1210 unsigned int *out_num, unsigned int *in_num,
1211 struct vhost_log *log, unsigned int *log_num)
1212 {
1213 struct vring_desc desc;
1214 unsigned int i, head, found = 0;
1215 u16 last_avail_idx;
1216 int ret;
1217
1218 /* Check it isn't doing very strange things with descriptor numbers. */
1219 last_avail_idx = vq->last_avail_idx;
1220 if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) {
1221 vq_err(vq, "Failed to access avail idx at %p\n",
1222 &vq->avail->idx);
1223 return -EFAULT;
1224 }
1225
1226 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1227 vq_err(vq, "Guest moved used index from %u to %u",
1228 last_avail_idx, vq->avail_idx);
1229 return -EFAULT;
1230 }
1231
1232 /* If there's nothing new since last we looked, return invalid. */
1233 if (vq->avail_idx == last_avail_idx)
1234 return vq->num;
1235
1236 /* Only get avail ring entries after they have been exposed by guest. */
1237 smp_rmb();
1238
1239 /* Grab the next descriptor number they're advertising, and increment
1240 * the index we've seen. */
1241 if (unlikely(__get_user(head,
1242 &vq->avail->ring[last_avail_idx % vq->num]))) {
1243 vq_err(vq, "Failed to read head: idx %d address %p\n",
1244 last_avail_idx,
1245 &vq->avail->ring[last_avail_idx % vq->num]);
1246 return -EFAULT;
1247 }
1248
1249 /* If their number is silly, that's an error. */
1250 if (unlikely(head >= vq->num)) {
1251 vq_err(vq, "Guest says index %u > %u is available",
1252 head, vq->num);
1253 return -EINVAL;
1254 }
1255
1256 /* When we start there are none of either input nor output. */
1257 *out_num = *in_num = 0;
1258 if (unlikely(log))
1259 *log_num = 0;
1260
1261 i = head;
1262 do {
1263 unsigned iov_count = *in_num + *out_num;
1264 if (unlikely(i >= vq->num)) {
1265 vq_err(vq, "Desc index is %u > %u, head = %u",
1266 i, vq->num, head);
1267 return -EINVAL;
1268 }
1269 if (unlikely(++found > vq->num)) {
1270 vq_err(vq, "Loop detected: last one at %u "
1271 "vq size %u head %u\n",
1272 i, vq->num, head);
1273 return -EINVAL;
1274 }
1275 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1276 if (unlikely(ret)) {
1277 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1278 i, vq->desc + i);
1279 return -EFAULT;
1280 }
1281 if (desc.flags & VRING_DESC_F_INDIRECT) {
1282 ret = get_indirect(dev, vq, iov, iov_size,
1283 out_num, in_num,
1284 log, log_num, &desc);
1285 if (unlikely(ret < 0)) {
1286 vq_err(vq, "Failure detected "
1287 "in indirect descriptor at idx %d\n", i);
1288 return ret;
1289 }
1290 continue;
1291 }
1292
1293 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1294 iov_size - iov_count);
1295 if (unlikely(ret < 0)) {
1296 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1297 ret, i);
1298 return ret;
1299 }
1300 if (desc.flags & VRING_DESC_F_WRITE) {
1301 /* If this is an input descriptor,
1302 * increment that count. */
1303 *in_num += ret;
1304 if (unlikely(log)) {
1305 log[*log_num].addr = desc.addr;
1306 log[*log_num].len = desc.len;
1307 ++*log_num;
1308 }
1309 } else {
1310 /* If it's an output descriptor, they're all supposed
1311 * to come before any input descriptors. */
1312 if (unlikely(*in_num)) {
1313 vq_err(vq, "Descriptor has out after in: "
1314 "idx %d\n", i);
1315 return -EINVAL;
1316 }
1317 *out_num += ret;
1318 }
1319 } while ((i = next_desc(&desc)) != -1);
1320
1321 /* On success, increment avail index. */
1322 vq->last_avail_idx++;
1323
1324 /* Assume notifications from guest are disabled at this point,
1325 * if they aren't we would need to update avail_event index. */
1326 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1327 return head;
1328 }
1329
1330 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1331 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1332 {
1333 vq->last_avail_idx -= n;
1334 }
1335
1336 /* After we've used one of their buffers, we tell them about it. We'll then
1337 * want to notify the guest, using eventfd. */
1338 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1339 {
1340 struct vring_used_elem __user *used;
1341
1342 /* The virtqueue contains a ring of used buffers. Get a pointer to the
1343 * next entry in that used ring. */
1344 used = &vq->used->ring[vq->last_used_idx % vq->num];
1345 if (__put_user(head, &used->id)) {
1346 vq_err(vq, "Failed to write used id");
1347 return -EFAULT;
1348 }
1349 if (__put_user(len, &used->len)) {
1350 vq_err(vq, "Failed to write used len");
1351 return -EFAULT;
1352 }
1353 /* Make sure buffer is written before we update index. */
1354 smp_wmb();
1355 if (__put_user(vq->last_used_idx + 1, &vq->used->idx)) {
1356 vq_err(vq, "Failed to increment used idx");
1357 return -EFAULT;
1358 }
1359 if (unlikely(vq->log_used)) {
1360 /* Make sure data is seen before log. */
1361 smp_wmb();
1362 /* Log used ring entry write. */
1363 log_write(vq->log_base,
1364 vq->log_addr +
1365 ((void __user *)used - (void __user *)vq->used),
1366 sizeof *used);
1367 /* Log used index update. */
1368 log_write(vq->log_base,
1369 vq->log_addr + offsetof(struct vring_used, idx),
1370 sizeof vq->used->idx);
1371 if (vq->log_ctx)
1372 eventfd_signal(vq->log_ctx, 1);
1373 }
1374 vq->last_used_idx++;
1375 /* If the driver never bothers to signal in a very long while,
1376 * used index might wrap around. If that happens, invalidate
1377 * signalled_used index we stored. TODO: make sure driver
1378 * signals at least once in 2^16 and remove this. */
1379 if (unlikely(vq->last_used_idx == vq->signalled_used))
1380 vq->signalled_used_valid = false;
1381 return 0;
1382 }
1383
1384 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1385 struct vring_used_elem *heads,
1386 unsigned count)
1387 {
1388 struct vring_used_elem __user *used;
1389 u16 old, new;
1390 int start;
1391
1392 start = vq->last_used_idx % vq->num;
1393 used = vq->used->ring + start;
1394 if (__copy_to_user(used, heads, count * sizeof *used)) {
1395 vq_err(vq, "Failed to write used");
1396 return -EFAULT;
1397 }
1398 if (unlikely(vq->log_used)) {
1399 /* Make sure data is seen before log. */
1400 smp_wmb();
1401 /* Log used ring entry write. */
1402 log_write(vq->log_base,
1403 vq->log_addr +
1404 ((void __user *)used - (void __user *)vq->used),
1405 count * sizeof *used);
1406 }
1407 old = vq->last_used_idx;
1408 new = (vq->last_used_idx += count);
1409 /* If the driver never bothers to signal in a very long while,
1410 * used index might wrap around. If that happens, invalidate
1411 * signalled_used index we stored. TODO: make sure driver
1412 * signals at least once in 2^16 and remove this. */
1413 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1414 vq->signalled_used_valid = false;
1415 return 0;
1416 }
1417
1418 /* After we've used one of their buffers, we tell them about it. We'll then
1419 * want to notify the guest, using eventfd. */
1420 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1421 unsigned count)
1422 {
1423 int start, n, r;
1424
1425 start = vq->last_used_idx % vq->num;
1426 n = vq->num - start;
1427 if (n < count) {
1428 r = __vhost_add_used_n(vq, heads, n);
1429 if (r < 0)
1430 return r;
1431 heads += n;
1432 count -= n;
1433 }
1434 r = __vhost_add_used_n(vq, heads, count);
1435
1436 /* Make sure buffer is written before we update index. */
1437 smp_wmb();
1438 if (put_user(vq->last_used_idx, &vq->used->idx)) {
1439 vq_err(vq, "Failed to increment used idx");
1440 return -EFAULT;
1441 }
1442 if (unlikely(vq->log_used)) {
1443 /* Log used index update. */
1444 log_write(vq->log_base,
1445 vq->log_addr + offsetof(struct vring_used, idx),
1446 sizeof vq->used->idx);
1447 if (vq->log_ctx)
1448 eventfd_signal(vq->log_ctx, 1);
1449 }
1450 return r;
1451 }
1452
1453 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1454 {
1455 __u16 old, new, event;
1456 bool v;
1457 /* Flush out used index updates. This is paired
1458 * with the barrier that the Guest executes when enabling
1459 * interrupts. */
1460 smp_mb();
1461
1462 if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1463 unlikely(vq->avail_idx == vq->last_avail_idx))
1464 return true;
1465
1466 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1467 __u16 flags;
1468 if (__get_user(flags, &vq->avail->flags)) {
1469 vq_err(vq, "Failed to get flags");
1470 return true;
1471 }
1472 return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
1473 }
1474 old = vq->signalled_used;
1475 v = vq->signalled_used_valid;
1476 new = vq->signalled_used = vq->last_used_idx;
1477 vq->signalled_used_valid = true;
1478
1479 if (unlikely(!v))
1480 return true;
1481
1482 if (get_user(event, vhost_used_event(vq))) {
1483 vq_err(vq, "Failed to get used event idx");
1484 return true;
1485 }
1486 return vring_need_event(event, new, old);
1487 }
1488
1489 /* This actually signals the guest, using eventfd. */
1490 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1491 {
1492 /* Signal the Guest tell them we used something up. */
1493 if (vq->call_ctx && vhost_notify(dev, vq))
1494 eventfd_signal(vq->call_ctx, 1);
1495 }
1496
1497 /* And here's the combo meal deal. Supersize me! */
1498 void vhost_add_used_and_signal(struct vhost_dev *dev,
1499 struct vhost_virtqueue *vq,
1500 unsigned int head, int len)
1501 {
1502 vhost_add_used(vq, head, len);
1503 vhost_signal(dev, vq);
1504 }
1505
1506 /* multi-buffer version of vhost_add_used_and_signal */
1507 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1508 struct vhost_virtqueue *vq,
1509 struct vring_used_elem *heads, unsigned count)
1510 {
1511 vhost_add_used_n(vq, heads, count);
1512 vhost_signal(dev, vq);
1513 }
1514
1515 /* OK, now we need to know about added descriptors. */
1516 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1517 {
1518 u16 avail_idx;
1519 int r;
1520
1521 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1522 return false;
1523 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1524 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1525 r = vhost_update_used_flags(vq);
1526 if (r) {
1527 vq_err(vq, "Failed to enable notification at %p: %d\n",
1528 &vq->used->flags, r);
1529 return false;
1530 }
1531 } else {
1532 r = vhost_update_avail_event(vq, vq->avail_idx);
1533 if (r) {
1534 vq_err(vq, "Failed to update avail event index at %p: %d\n",
1535 vhost_avail_event(vq), r);
1536 return false;
1537 }
1538 }
1539 /* They could have slipped one in as we were doing that: make
1540 * sure it's written, then check again. */
1541 smp_mb();
1542 r = __get_user(avail_idx, &vq->avail->idx);
1543 if (r) {
1544 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1545 &vq->avail->idx, r);
1546 return false;
1547 }
1548
1549 return avail_idx != vq->avail_idx;
1550 }
1551
1552 /* We don't need to be notified again. */
1553 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1554 {
1555 int r;
1556
1557 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1558 return;
1559 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1560 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1561 r = vhost_update_used_flags(vq);
1562 if (r)
1563 vq_err(vq, "Failed to enable notification at %p: %d\n",
1564 &vq->used->flags, r);
1565 }
1566 }
1567
1568 static void vhost_zerocopy_done_signal(struct kref *kref)
1569 {
1570 struct vhost_ubuf_ref *ubufs = container_of(kref, struct vhost_ubuf_ref,
1571 kref);
1572 wake_up(&ubufs->wait);
1573 }
1574
1575 struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *vq,
1576 bool zcopy)
1577 {
1578 struct vhost_ubuf_ref *ubufs;
1579 /* No zero copy backend? Nothing to count. */
1580 if (!zcopy)
1581 return NULL;
1582 ubufs = kmalloc(sizeof *ubufs, GFP_KERNEL);
1583 if (!ubufs)
1584 return ERR_PTR(-ENOMEM);
1585 kref_init(&ubufs->kref);
1586 init_waitqueue_head(&ubufs->wait);
1587 ubufs->vq = vq;
1588 return ubufs;
1589 }
1590
1591 void vhost_ubuf_put(struct vhost_ubuf_ref *ubufs)
1592 {
1593 kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1594 }
1595
1596 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *ubufs)
1597 {
1598 kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1599 wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount));
1600 kfree(ubufs);
1601 }
1602
1603 void vhost_zerocopy_callback(struct ubuf_info *ubuf)
1604 {
1605 struct vhost_ubuf_ref *ubufs = ubuf->ctx;
1606 struct vhost_virtqueue *vq = ubufs->vq;
1607
1608 vhost_poll_queue(&vq->poll);
1609 /* set len = 1 to mark this desc buffers done DMA */
1610 vq->heads[ubuf->desc].len = VHOST_DMA_DONE_LEN;
1611 kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1612 }
kernel source for telekom puls (alcatel/mediatek)