media: ov5640: Add Omnivision OV5640 support
[linux-2.6.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 static 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 static inline void vhost_work_queue(struct vhost_dev *dev,
141                                     struct vhost_work *work)
142 {
143         unsigned long flags;
144
145         spin_lock_irqsave(&dev->work_lock, flags);
146         if (list_empty(&work->node)) {
147                 list_add_tail(&work->node, &dev->work_list);
148                 work->queue_seq++;
149                 wake_up_process(dev->worker);
150         }
151         spin_unlock_irqrestore(&dev->work_lock, flags);
152 }
153
154 void vhost_poll_queue(struct vhost_poll *poll)
155 {
156         vhost_work_queue(poll->dev, &poll->work);
157 }
158
159 static void vhost_vq_reset(struct vhost_dev *dev,
160                            struct vhost_virtqueue *vq)
161 {
162         vq->num = 1;
163         vq->desc = NULL;
164         vq->avail = NULL;
165         vq->used = NULL;
166         vq->last_avail_idx = 0;
167         vq->avail_idx = 0;
168         vq->last_used_idx = 0;
169         vq->signalled_used = 0;
170         vq->signalled_used_valid = false;
171         vq->used_flags = 0;
172         vq->log_used = false;
173         vq->log_addr = -1ull;
174         vq->vhost_hlen = 0;
175         vq->sock_hlen = 0;
176         vq->private_data = NULL;
177         vq->log_base = NULL;
178         vq->error_ctx = NULL;
179         vq->error = NULL;
180         vq->kick = NULL;
181         vq->call_ctx = NULL;
182         vq->call = NULL;
183         vq->log_ctx = NULL;
184         vq->upend_idx = 0;
185         vq->done_idx = 0;
186         vq->ubufs = NULL;
187 }
188
189 static int vhost_worker(void *data)
190 {
191         struct vhost_dev *dev = data;
192         struct vhost_work *work = NULL;
193         unsigned uninitialized_var(seq);
194
195         use_mm(dev->mm);
196
197         for (;;) {
198                 /* mb paired w/ kthread_stop */
199                 set_current_state(TASK_INTERRUPTIBLE);
200
201                 spin_lock_irq(&dev->work_lock);
202                 if (work) {
203                         work->done_seq = seq;
204                         if (work->flushing)
205                                 wake_up_all(&work->done);
206                 }
207
208                 if (kthread_should_stop()) {
209                         spin_unlock_irq(&dev->work_lock);
210                         __set_current_state(TASK_RUNNING);
211                         break;
212                 }
213                 if (!list_empty(&dev->work_list)) {
214                         work = list_first_entry(&dev->work_list,
215                                                 struct vhost_work, node);
216                         list_del_init(&work->node);
217                         seq = work->queue_seq;
218                 } else
219                         work = NULL;
220                 spin_unlock_irq(&dev->work_lock);
221
222                 if (work) {
223                         __set_current_state(TASK_RUNNING);
224                         work->fn(work);
225                 } else
226                         schedule();
227
228         }
229         unuse_mm(dev->mm);
230         return 0;
231 }
232
233 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
234 {
235         kfree(vq->indirect);
236         vq->indirect = NULL;
237         kfree(vq->log);
238         vq->log = NULL;
239         kfree(vq->heads);
240         vq->heads = NULL;
241         kfree(vq->ubuf_info);
242         vq->ubuf_info = NULL;
243 }
244
245 void vhost_enable_zcopy(int vq)
246 {
247         vhost_zcopy_mask |= 0x1 << vq;
248 }
249
250 /* Helper to allocate iovec buffers for all vqs. */
251 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
252 {
253         int i;
254         bool zcopy;
255
256         for (i = 0; i < dev->nvqs; ++i) {
257                 dev->vqs[i].indirect = kmalloc(sizeof *dev->vqs[i].indirect *
258                                                UIO_MAXIOV, GFP_KERNEL);
259                 dev->vqs[i].log = kmalloc(sizeof *dev->vqs[i].log * UIO_MAXIOV,
260                                           GFP_KERNEL);
261                 dev->vqs[i].heads = kmalloc(sizeof *dev->vqs[i].heads *
262                                             UIO_MAXIOV, GFP_KERNEL);
263                 zcopy = vhost_zcopy_mask & (0x1 << i);
264                 if (zcopy)
265                         dev->vqs[i].ubuf_info =
266                                 kmalloc(sizeof *dev->vqs[i].ubuf_info *
267                                         UIO_MAXIOV, GFP_KERNEL);
268                 if (!dev->vqs[i].indirect || !dev->vqs[i].log ||
269                         !dev->vqs[i].heads ||
270                         (zcopy && !dev->vqs[i].ubuf_info))
271                         goto err_nomem;
272         }
273         return 0;
274
275 err_nomem:
276         for (; i >= 0; --i)
277                 vhost_vq_free_iovecs(&dev->vqs[i]);
278         return -ENOMEM;
279 }
280
281 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
282 {
283         int i;
284
285         for (i = 0; i < dev->nvqs; ++i)
286                 vhost_vq_free_iovecs(&dev->vqs[i]);
287 }
288
289 long vhost_dev_init(struct vhost_dev *dev,
290                     struct vhost_virtqueue *vqs, int nvqs)
291 {
292         int i;
293
294         dev->vqs = vqs;
295         dev->nvqs = nvqs;
296         mutex_init(&dev->mutex);
297         dev->log_ctx = NULL;
298         dev->log_file = NULL;
299         dev->memory = NULL;
300         dev->mm = NULL;
301         spin_lock_init(&dev->work_lock);
302         INIT_LIST_HEAD(&dev->work_list);
303         dev->worker = NULL;
304
305         for (i = 0; i < dev->nvqs; ++i) {
306                 dev->vqs[i].log = NULL;
307                 dev->vqs[i].indirect = NULL;
308                 dev->vqs[i].heads = NULL;
309                 dev->vqs[i].ubuf_info = NULL;
310                 dev->vqs[i].dev = dev;
311                 mutex_init(&dev->vqs[i].mutex);
312                 vhost_vq_reset(dev, dev->vqs + i);
313                 if (dev->vqs[i].handle_kick)
314                         vhost_poll_init(&dev->vqs[i].poll,
315                                         dev->vqs[i].handle_kick, POLLIN, dev);
316         }
317
318         return 0;
319 }
320
321 /* Caller should have device mutex */
322 long vhost_dev_check_owner(struct vhost_dev *dev)
323 {
324         /* Are you the owner? If not, I don't think you mean to do that */
325         return dev->mm == current->mm ? 0 : -EPERM;
326 }
327
328 struct vhost_attach_cgroups_struct {
329         struct vhost_work work;
330         struct task_struct *owner;
331         int ret;
332 };
333
334 static void vhost_attach_cgroups_work(struct vhost_work *work)
335 {
336         struct vhost_attach_cgroups_struct *s;
337
338         s = container_of(work, struct vhost_attach_cgroups_struct, work);
339         s->ret = cgroup_attach_task_all(s->owner, current);
340 }
341
342 static int vhost_attach_cgroups(struct vhost_dev *dev)
343 {
344         struct vhost_attach_cgroups_struct attach;
345
346         attach.owner = current;
347         vhost_work_init(&attach.work, vhost_attach_cgroups_work);
348         vhost_work_queue(dev, &attach.work);
349         vhost_work_flush(dev, &attach.work);
350         return attach.ret;
351 }
352
353 /* Caller should have device mutex */
354 static long vhost_dev_set_owner(struct vhost_dev *dev)
355 {
356         struct task_struct *worker;
357         int err;
358
359         /* Is there an owner already? */
360         if (dev->mm) {
361                 err = -EBUSY;
362                 goto err_mm;
363         }
364
365         /* No owner, become one */
366         dev->mm = get_task_mm(current);
367         worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
368         if (IS_ERR(worker)) {
369                 err = PTR_ERR(worker);
370                 goto err_worker;
371         }
372
373         dev->worker = worker;
374         wake_up_process(worker);        /* avoid contributing to loadavg */
375
376         err = vhost_attach_cgroups(dev);
377         if (err)
378                 goto err_cgroup;
379
380         err = vhost_dev_alloc_iovecs(dev);
381         if (err)
382                 goto err_cgroup;
383
384         return 0;
385 err_cgroup:
386         kthread_stop(worker);
387         dev->worker = NULL;
388 err_worker:
389         if (dev->mm)
390                 mmput(dev->mm);
391         dev->mm = NULL;
392 err_mm:
393         return err;
394 }
395
396 /* Caller should have device mutex */
397 long vhost_dev_reset_owner(struct vhost_dev *dev)
398 {
399         struct vhost_memory *memory;
400
401         /* Restore memory to default empty mapping. */
402         memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
403         if (!memory)
404                 return -ENOMEM;
405
406         vhost_dev_cleanup(dev);
407
408         memory->nregions = 0;
409         RCU_INIT_POINTER(dev->memory, memory);
410         return 0;
411 }
412
413 /* In case of DMA done not in order in lower device driver for some reason.
414  * upend_idx is used to track end of used idx, done_idx is used to track head
415  * of used idx. Once lower device DMA done contiguously, we will signal KVM
416  * guest used idx.
417  */
418 int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq)
419 {
420         int i;
421         int j = 0;
422
423         for (i = vq->done_idx; i != vq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
424                 if ((vq->heads[i].len == VHOST_DMA_DONE_LEN)) {
425                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
426                         vhost_add_used_and_signal(vq->dev, vq,
427                                                   vq->heads[i].id, 0);
428                         ++j;
429                 } else
430                         break;
431         }
432         if (j)
433                 vq->done_idx = i;
434         return j;
435 }
436
437 /* Caller should have device mutex */
438 void vhost_dev_cleanup(struct vhost_dev *dev)
439 {
440         int i;
441
442         for (i = 0; i < dev->nvqs; ++i) {
443                 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) {
444                         vhost_poll_stop(&dev->vqs[i].poll);
445                         vhost_poll_flush(&dev->vqs[i].poll);
446                 }
447                 /* Wait for all lower device DMAs done. */
448                 if (dev->vqs[i].ubufs)
449                         vhost_ubuf_put_and_wait(dev->vqs[i].ubufs);
450
451                 /* Signal guest as appropriate. */
452                 vhost_zerocopy_signal_used(&dev->vqs[i]);
453
454                 if (dev->vqs[i].error_ctx)
455                         eventfd_ctx_put(dev->vqs[i].error_ctx);
456                 if (dev->vqs[i].error)
457                         fput(dev->vqs[i].error);
458                 if (dev->vqs[i].kick)
459                         fput(dev->vqs[i].kick);
460                 if (dev->vqs[i].call_ctx)
461                         eventfd_ctx_put(dev->vqs[i].call_ctx);
462                 if (dev->vqs[i].call)
463                         fput(dev->vqs[i].call);
464                 vhost_vq_reset(dev, dev->vqs + i);
465         }
466         vhost_dev_free_iovecs(dev);
467         if (dev->log_ctx)
468                 eventfd_ctx_put(dev->log_ctx);
469         dev->log_ctx = NULL;
470         if (dev->log_file)
471                 fput(dev->log_file);
472         dev->log_file = NULL;
473         /* No one will access memory at this point */
474         kfree(rcu_dereference_protected(dev->memory,
475                                         lockdep_is_held(&dev->mutex)));
476         RCU_INIT_POINTER(dev->memory, NULL);
477         WARN_ON(!list_empty(&dev->work_list));
478         if (dev->worker) {
479                 kthread_stop(dev->worker);
480                 dev->worker = NULL;
481         }
482         if (dev->mm)
483                 mmput(dev->mm);
484         dev->mm = NULL;
485 }
486
487 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
488 {
489         u64 a = addr / VHOST_PAGE_SIZE / 8;
490
491         /* Make sure 64 bit math will not overflow. */
492         if (a > ULONG_MAX - (unsigned long)log_base ||
493             a + (unsigned long)log_base > ULONG_MAX)
494                 return 0;
495
496         return access_ok(VERIFY_WRITE, log_base + a,
497                          (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
498 }
499
500 /* Caller should have vq mutex and device mutex. */
501 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
502                                int log_all)
503 {
504         int i;
505
506         if (!mem)
507                 return 0;
508
509         for (i = 0; i < mem->nregions; ++i) {
510                 struct vhost_memory_region *m = mem->regions + i;
511                 unsigned long a = m->userspace_addr;
512                 if (m->memory_size > ULONG_MAX)
513                         return 0;
514                 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
515                                     m->memory_size))
516                         return 0;
517                 else if (log_all && !log_access_ok(log_base,
518                                                    m->guest_phys_addr,
519                                                    m->memory_size))
520                         return 0;
521         }
522         return 1;
523 }
524
525 /* Can we switch to this memory table? */
526 /* Caller should have device mutex but not vq mutex */
527 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
528                             int log_all)
529 {
530         int i;
531
532         for (i = 0; i < d->nvqs; ++i) {
533                 int ok;
534                 mutex_lock(&d->vqs[i].mutex);
535                 /* If ring is inactive, will check when it's enabled. */
536                 if (d->vqs[i].private_data)
537                         ok = vq_memory_access_ok(d->vqs[i].log_base, mem,
538                                                  log_all);
539                 else
540                         ok = 1;
541                 mutex_unlock(&d->vqs[i].mutex);
542                 if (!ok)
543                         return 0;
544         }
545         return 1;
546 }
547
548 static int vq_access_ok(struct vhost_dev *d, unsigned int num,
549                         struct vring_desc __user *desc,
550                         struct vring_avail __user *avail,
551                         struct vring_used __user *used)
552 {
553         size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
554         return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
555                access_ok(VERIFY_READ, avail,
556                          sizeof *avail + num * sizeof *avail->ring + s) &&
557                access_ok(VERIFY_WRITE, used,
558                         sizeof *used + num * sizeof *used->ring + s);
559 }
560
561 /* Can we log writes? */
562 /* Caller should have device mutex but not vq mutex */
563 int vhost_log_access_ok(struct vhost_dev *dev)
564 {
565         struct vhost_memory *mp;
566
567         mp = rcu_dereference_protected(dev->memory,
568                                        lockdep_is_held(&dev->mutex));
569         return memory_access_ok(dev, mp, 1);
570 }
571
572 /* Verify access for write logging. */
573 /* Caller should have vq mutex and device mutex */
574 static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
575                             void __user *log_base)
576 {
577         struct vhost_memory *mp;
578         size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
579
580         mp = rcu_dereference_protected(vq->dev->memory,
581                                        lockdep_is_held(&vq->mutex));
582         return vq_memory_access_ok(log_base, mp,
583                             vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
584                 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
585                                         sizeof *vq->used +
586                                         vq->num * sizeof *vq->used->ring + s));
587 }
588
589 /* Can we start vq? */
590 /* Caller should have vq mutex and device mutex */
591 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
592 {
593         return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
594                 vq_log_access_ok(vq->dev, vq, vq->log_base);
595 }
596
597 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
598 {
599         struct vhost_memory mem, *newmem, *oldmem;
600         unsigned long size = offsetof(struct vhost_memory, regions);
601
602         if (copy_from_user(&mem, m, size))
603                 return -EFAULT;
604         if (mem.padding)
605                 return -EOPNOTSUPP;
606         if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
607                 return -E2BIG;
608         newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL);
609         if (!newmem)
610                 return -ENOMEM;
611
612         memcpy(newmem, &mem, size);
613         if (copy_from_user(newmem->regions, m->regions,
614                            mem.nregions * sizeof *m->regions)) {
615                 kfree(newmem);
616                 return -EFAULT;
617         }
618
619         if (!memory_access_ok(d, newmem,
620                               vhost_has_feature(d, VHOST_F_LOG_ALL))) {
621                 kfree(newmem);
622                 return -EFAULT;
623         }
624         oldmem = rcu_dereference_protected(d->memory,
625                                            lockdep_is_held(&d->mutex));
626         rcu_assign_pointer(d->memory, newmem);
627         synchronize_rcu();
628         kfree(oldmem);
629         return 0;
630 }
631
632 static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
633 {
634         struct file *eventfp, *filep = NULL,
635                     *pollstart = NULL, *pollstop = NULL;
636         struct eventfd_ctx *ctx = NULL;
637         u32 __user *idxp = argp;
638         struct vhost_virtqueue *vq;
639         struct vhost_vring_state s;
640         struct vhost_vring_file f;
641         struct vhost_vring_addr a;
642         u32 idx;
643         long r;
644
645         r = get_user(idx, idxp);
646         if (r < 0)
647                 return r;
648         if (idx >= d->nvqs)
649                 return -ENOBUFS;
650
651         vq = d->vqs + idx;
652
653         mutex_lock(&vq->mutex);
654
655         switch (ioctl) {
656         case VHOST_SET_VRING_NUM:
657                 /* Resizing ring with an active backend?
658                  * You don't want to do that. */
659                 if (vq->private_data) {
660                         r = -EBUSY;
661                         break;
662                 }
663                 if (copy_from_user(&s, argp, sizeof s)) {
664                         r = -EFAULT;
665                         break;
666                 }
667                 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
668                         r = -EINVAL;
669                         break;
670                 }
671                 vq->num = s.num;
672                 break;
673         case VHOST_SET_VRING_BASE:
674                 /* Moving base with an active backend?
675                  * You don't want to do that. */
676                 if (vq->private_data) {
677                         r = -EBUSY;
678                         break;
679                 }
680                 if (copy_from_user(&s, argp, sizeof s)) {
681                         r = -EFAULT;
682                         break;
683                 }
684                 if (s.num > 0xffff) {
685                         r = -EINVAL;
686                         break;
687                 }
688                 vq->last_avail_idx = s.num;
689                 /* Forget the cached index value. */
690                 vq->avail_idx = vq->last_avail_idx;
691                 break;
692         case VHOST_GET_VRING_BASE:
693                 s.index = idx;
694                 s.num = vq->last_avail_idx;
695                 if (copy_to_user(argp, &s, sizeof s))
696                         r = -EFAULT;
697                 break;
698         case VHOST_SET_VRING_ADDR:
699                 if (copy_from_user(&a, argp, sizeof a)) {
700                         r = -EFAULT;
701                         break;
702                 }
703                 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
704                         r = -EOPNOTSUPP;
705                         break;
706                 }
707                 /* For 32bit, verify that the top 32bits of the user
708                    data are set to zero. */
709                 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
710                     (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
711                     (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
712                         r = -EFAULT;
713                         break;
714                 }
715                 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
716                     (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
717                     (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
718                         r = -EINVAL;
719                         break;
720                 }
721
722                 /* We only verify access here if backend is configured.
723                  * If it is not, we don't as size might not have been setup.
724                  * We will verify when backend is configured. */
725                 if (vq->private_data) {
726                         if (!vq_access_ok(d, vq->num,
727                                 (void __user *)(unsigned long)a.desc_user_addr,
728                                 (void __user *)(unsigned long)a.avail_user_addr,
729                                 (void __user *)(unsigned long)a.used_user_addr)) {
730                                 r = -EINVAL;
731                                 break;
732                         }
733
734                         /* Also validate log access for used ring if enabled. */
735                         if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
736                             !log_access_ok(vq->log_base, a.log_guest_addr,
737                                            sizeof *vq->used +
738                                            vq->num * sizeof *vq->used->ring)) {
739                                 r = -EINVAL;
740                                 break;
741                         }
742                 }
743
744                 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
745                 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
746                 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
747                 vq->log_addr = a.log_guest_addr;
748                 vq->used = (void __user *)(unsigned long)a.used_user_addr;
749                 break;
750         case VHOST_SET_VRING_KICK:
751                 if (copy_from_user(&f, argp, sizeof f)) {
752                         r = -EFAULT;
753                         break;
754                 }
755                 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
756                 if (IS_ERR(eventfp)) {
757                         r = PTR_ERR(eventfp);
758                         break;
759                 }
760                 if (eventfp != vq->kick) {
761                         pollstop = filep = vq->kick;
762                         pollstart = vq->kick = eventfp;
763                 } else
764                         filep = eventfp;
765                 break;
766         case VHOST_SET_VRING_CALL:
767                 if (copy_from_user(&f, argp, sizeof f)) {
768                         r = -EFAULT;
769                         break;
770                 }
771                 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
772                 if (IS_ERR(eventfp)) {
773                         r = PTR_ERR(eventfp);
774                         break;
775                 }
776                 if (eventfp != vq->call) {
777                         filep = vq->call;
778                         ctx = vq->call_ctx;
779                         vq->call = eventfp;
780                         vq->call_ctx = eventfp ?
781                                 eventfd_ctx_fileget(eventfp) : NULL;
782                 } else
783                         filep = eventfp;
784                 break;
785         case VHOST_SET_VRING_ERR:
786                 if (copy_from_user(&f, argp, sizeof f)) {
787                         r = -EFAULT;
788                         break;
789                 }
790                 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
791                 if (IS_ERR(eventfp)) {
792                         r = PTR_ERR(eventfp);
793                         break;
794                 }
795                 if (eventfp != vq->error) {
796                         filep = vq->error;
797                         vq->error = eventfp;
798                         ctx = vq->error_ctx;
799                         vq->error_ctx = eventfp ?
800                                 eventfd_ctx_fileget(eventfp) : NULL;
801                 } else
802                         filep = eventfp;
803                 break;
804         default:
805                 r = -ENOIOCTLCMD;
806         }
807
808         if (pollstop && vq->handle_kick)
809                 vhost_poll_stop(&vq->poll);
810
811         if (ctx)
812                 eventfd_ctx_put(ctx);
813         if (filep)
814                 fput(filep);
815
816         if (pollstart && vq->handle_kick)
817                 vhost_poll_start(&vq->poll, vq->kick);
818
819         mutex_unlock(&vq->mutex);
820
821         if (pollstop && vq->handle_kick)
822                 vhost_poll_flush(&vq->poll);
823         return r;
824 }
825
826 /* Caller must have device mutex */
827 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
828 {
829         void __user *argp = (void __user *)arg;
830         struct file *eventfp, *filep = NULL;
831         struct eventfd_ctx *ctx = NULL;
832         u64 p;
833         long r;
834         int i, fd;
835
836         /* If you are not the owner, you can become one */
837         if (ioctl == VHOST_SET_OWNER) {
838                 r = vhost_dev_set_owner(d);
839                 goto done;
840         }
841
842         /* You must be the owner to do anything else */
843         r = vhost_dev_check_owner(d);
844         if (r)
845                 goto done;
846
847         switch (ioctl) {
848         case VHOST_SET_MEM_TABLE:
849                 r = vhost_set_memory(d, argp);
850                 break;
851         case VHOST_SET_LOG_BASE:
852                 if (copy_from_user(&p, argp, sizeof p)) {
853                         r = -EFAULT;
854                         break;
855                 }
856                 if ((u64)(unsigned long)p != p) {
857                         r = -EFAULT;
858                         break;
859                 }
860                 for (i = 0; i < d->nvqs; ++i) {
861                         struct vhost_virtqueue *vq;
862                         void __user *base = (void __user *)(unsigned long)p;
863                         vq = d->vqs + i;
864                         mutex_lock(&vq->mutex);
865                         /* If ring is inactive, will check when it's enabled. */
866                         if (vq->private_data && !vq_log_access_ok(d, vq, base))
867                                 r = -EFAULT;
868                         else
869                                 vq->log_base = base;
870                         mutex_unlock(&vq->mutex);
871                 }
872                 break;
873         case VHOST_SET_LOG_FD:
874                 r = get_user(fd, (int __user *)argp);
875                 if (r < 0)
876                         break;
877                 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
878                 if (IS_ERR(eventfp)) {
879                         r = PTR_ERR(eventfp);
880                         break;
881                 }
882                 if (eventfp != d->log_file) {
883                         filep = d->log_file;
884                         ctx = d->log_ctx;
885                         d->log_ctx = eventfp ?
886                                 eventfd_ctx_fileget(eventfp) : NULL;
887                 } else
888                         filep = eventfp;
889                 for (i = 0; i < d->nvqs; ++i) {
890                         mutex_lock(&d->vqs[i].mutex);
891                         d->vqs[i].log_ctx = d->log_ctx;
892                         mutex_unlock(&d->vqs[i].mutex);
893                 }
894                 if (ctx)
895                         eventfd_ctx_put(ctx);
896                 if (filep)
897                         fput(filep);
898                 break;
899         default:
900                 r = vhost_set_vring(d, ioctl, argp);
901                 break;
902         }
903 done:
904         return r;
905 }
906
907 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
908                                                      __u64 addr, __u32 len)
909 {
910         struct vhost_memory_region *reg;
911         int i;
912
913         /* linear search is not brilliant, but we really have on the order of 6
914          * regions in practice */
915         for (i = 0; i < mem->nregions; ++i) {
916                 reg = mem->regions + i;
917                 if (reg->guest_phys_addr <= addr &&
918                     reg->guest_phys_addr + reg->memory_size - 1 >= addr)
919                         return reg;
920         }
921         return NULL;
922 }
923
924 /* TODO: This is really inefficient.  We need something like get_user()
925  * (instruction directly accesses the data, with an exception table entry
926  * returning -EFAULT). See Documentation/x86/exception-tables.txt.
927  */
928 static int set_bit_to_user(int nr, void __user *addr)
929 {
930         unsigned long log = (unsigned long)addr;
931         struct page *page;
932         void *base;
933         int bit = nr + (log % PAGE_SIZE) * 8;
934         int r;
935
936         r = get_user_pages_fast(log, 1, 1, &page);
937         if (r < 0)
938                 return r;
939         BUG_ON(r != 1);
940         base = kmap_atomic(page, KM_USER0);
941         set_bit(bit, base);
942         kunmap_atomic(base, KM_USER0);
943         set_page_dirty_lock(page);
944         put_page(page);
945         return 0;
946 }
947
948 static int log_write(void __user *log_base,
949                      u64 write_address, u64 write_length)
950 {
951         u64 write_page = write_address / VHOST_PAGE_SIZE;
952         int r;
953
954         if (!write_length)
955                 return 0;
956         write_length += write_address % VHOST_PAGE_SIZE;
957         for (;;) {
958                 u64 base = (u64)(unsigned long)log_base;
959                 u64 log = base + write_page / 8;
960                 int bit = write_page % 8;
961                 if ((u64)(unsigned long)log != log)
962                         return -EFAULT;
963                 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
964                 if (r < 0)
965                         return r;
966                 if (write_length <= VHOST_PAGE_SIZE)
967                         break;
968                 write_length -= VHOST_PAGE_SIZE;
969                 write_page += 1;
970         }
971         return r;
972 }
973
974 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
975                     unsigned int log_num, u64 len)
976 {
977         int i, r;
978
979         /* Make sure data written is seen before log. */
980         smp_wmb();
981         for (i = 0; i < log_num; ++i) {
982                 u64 l = min(log[i].len, len);
983                 r = log_write(vq->log_base, log[i].addr, l);
984                 if (r < 0)
985                         return r;
986                 len -= l;
987                 if (!len) {
988                         if (vq->log_ctx)
989                                 eventfd_signal(vq->log_ctx, 1);
990                         return 0;
991                 }
992         }
993         /* Length written exceeds what we have stored. This is a bug. */
994         BUG();
995         return 0;
996 }
997
998 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
999 {
1000         void __user *used;
1001         if (__put_user(vq->used_flags, &vq->used->flags) < 0)
1002                 return -EFAULT;
1003         if (unlikely(vq->log_used)) {
1004                 /* Make sure the flag is seen before log. */
1005                 smp_wmb();
1006                 /* Log used flag write. */
1007                 used = &vq->used->flags;
1008                 log_write(vq->log_base, vq->log_addr +
1009                           (used - (void __user *)vq->used),
1010                           sizeof vq->used->flags);
1011                 if (vq->log_ctx)
1012                         eventfd_signal(vq->log_ctx, 1);
1013         }
1014         return 0;
1015 }
1016
1017 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1018 {
1019         if (__put_user(vq->avail_idx, vhost_avail_event(vq)))
1020                 return -EFAULT;
1021         if (unlikely(vq->log_used)) {
1022                 void __user *used;
1023                 /* Make sure the event is seen before log. */
1024                 smp_wmb();
1025                 /* Log avail event write */
1026                 used = vhost_avail_event(vq);
1027                 log_write(vq->log_base, vq->log_addr +
1028                           (used - (void __user *)vq->used),
1029                           sizeof *vhost_avail_event(vq));
1030                 if (vq->log_ctx)
1031                         eventfd_signal(vq->log_ctx, 1);
1032         }
1033         return 0;
1034 }
1035
1036 int vhost_init_used(struct vhost_virtqueue *vq)
1037 {
1038         int r;
1039         if (!vq->private_data)
1040                 return 0;
1041
1042         r = vhost_update_used_flags(vq);
1043         if (r)
1044                 return r;
1045         vq->signalled_used_valid = false;
1046         return get_user(vq->last_used_idx, &vq->used->idx);
1047 }
1048
1049 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
1050                           struct iovec iov[], int iov_size)
1051 {
1052         const struct vhost_memory_region *reg;
1053         struct vhost_memory *mem;
1054         struct iovec *_iov;
1055         u64 s = 0;
1056         int ret = 0;
1057
1058         rcu_read_lock();
1059
1060         mem = rcu_dereference(dev->memory);
1061         while ((u64)len > s) {
1062                 u64 size;
1063                 if (unlikely(ret >= iov_size)) {
1064                         ret = -ENOBUFS;
1065                         break;
1066                 }
1067                 reg = find_region(mem, addr, len);
1068                 if (unlikely(!reg)) {
1069                         ret = -EFAULT;
1070                         break;
1071                 }
1072                 _iov = iov + ret;
1073                 size = reg->memory_size - addr + reg->guest_phys_addr;
1074                 _iov->iov_len = min((u64)len, size);
1075                 _iov->iov_base = (void __user *)(unsigned long)
1076                         (reg->userspace_addr + addr - reg->guest_phys_addr);
1077                 s += size;
1078                 addr += size;
1079                 ++ret;
1080         }
1081
1082         rcu_read_unlock();
1083         return ret;
1084 }
1085
1086 /* Each buffer in the virtqueues is actually a chain of descriptors.  This
1087  * function returns the next descriptor in the chain,
1088  * or -1U if we're at the end. */
1089 static unsigned next_desc(struct vring_desc *desc)
1090 {
1091         unsigned int next;
1092
1093         /* If this descriptor says it doesn't chain, we're done. */
1094         if (!(desc->flags & VRING_DESC_F_NEXT))
1095                 return -1U;
1096
1097         /* Check they're not leading us off end of descriptors. */
1098         next = desc->next;
1099         /* Make sure compiler knows to grab that: we don't want it changing! */
1100         /* We will use the result as an index in an array, so most
1101          * architectures only need a compiler barrier here. */
1102         read_barrier_depends();
1103
1104         return next;
1105 }
1106
1107 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1108                         struct iovec iov[], unsigned int iov_size,
1109                         unsigned int *out_num, unsigned int *in_num,
1110                         struct vhost_log *log, unsigned int *log_num,
1111                         struct vring_desc *indirect)
1112 {
1113         struct vring_desc desc;
1114         unsigned int i = 0, count, found = 0;
1115         int ret;
1116
1117         /* Sanity check */
1118         if (unlikely(indirect->len % sizeof desc)) {
1119                 vq_err(vq, "Invalid length in indirect descriptor: "
1120                        "len 0x%llx not multiple of 0x%zx\n",
1121                        (unsigned long long)indirect->len,
1122                        sizeof desc);
1123                 return -EINVAL;
1124         }
1125
1126         ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect,
1127                              UIO_MAXIOV);
1128         if (unlikely(ret < 0)) {
1129                 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1130                 return ret;
1131         }
1132
1133         /* We will use the result as an address to read from, so most
1134          * architectures only need a compiler barrier here. */
1135         read_barrier_depends();
1136
1137         count = indirect->len / sizeof desc;
1138         /* Buffers are chained via a 16 bit next field, so
1139          * we can have at most 2^16 of these. */
1140         if (unlikely(count > USHRT_MAX + 1)) {
1141                 vq_err(vq, "Indirect buffer length too big: %d\n",
1142                        indirect->len);
1143                 return -E2BIG;
1144         }
1145
1146         do {
1147                 unsigned iov_count = *in_num + *out_num;
1148                 if (unlikely(++found > count)) {
1149                         vq_err(vq, "Loop detected: last one at %u "
1150                                "indirect size %u\n",
1151                                i, count);
1152                         return -EINVAL;
1153                 }
1154                 if (unlikely(memcpy_fromiovec((unsigned char *)&desc,
1155                                               vq->indirect, sizeof desc))) {
1156                         vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1157                                i, (size_t)indirect->addr + i * sizeof desc);
1158                         return -EINVAL;
1159                 }
1160                 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
1161                         vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1162                                i, (size_t)indirect->addr + i * sizeof desc);
1163                         return -EINVAL;
1164                 }
1165
1166                 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1167                                      iov_size - iov_count);
1168                 if (unlikely(ret < 0)) {
1169                         vq_err(vq, "Translation failure %d indirect idx %d\n",
1170                                ret, i);
1171                         return ret;
1172                 }
1173                 /* If this is an input descriptor, increment that count. */
1174                 if (desc.flags & VRING_DESC_F_WRITE) {
1175                         *in_num += ret;
1176                         if (unlikely(log)) {
1177                                 log[*log_num].addr = desc.addr;
1178                                 log[*log_num].len = desc.len;
1179                                 ++*log_num;
1180                         }
1181                 } else {
1182                         /* If it's an output descriptor, they're all supposed
1183                          * to come before any input descriptors. */
1184                         if (unlikely(*in_num)) {
1185                                 vq_err(vq, "Indirect descriptor "
1186                                        "has out after in: idx %d\n", i);
1187                                 return -EINVAL;
1188                         }
1189                         *out_num += ret;
1190                 }
1191         } while ((i = next_desc(&desc)) != -1);
1192         return 0;
1193 }
1194
1195 /* This looks in the virtqueue and for the first available buffer, and converts
1196  * it to an iovec for convenient access.  Since descriptors consist of some
1197  * number of output then some number of input descriptors, it's actually two
1198  * iovecs, but we pack them into one and note how many of each there were.
1199  *
1200  * This function returns the descriptor number found, or vq->num (which is
1201  * never a valid descriptor number) if none was found.  A negative code is
1202  * returned on error. */
1203 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1204                       struct iovec iov[], unsigned int iov_size,
1205                       unsigned int *out_num, unsigned int *in_num,
1206                       struct vhost_log *log, unsigned int *log_num)
1207 {
1208         struct vring_desc desc;
1209         unsigned int i, head, found = 0;
1210         u16 last_avail_idx;
1211         int ret;
1212
1213         /* Check it isn't doing very strange things with descriptor numbers. */
1214         last_avail_idx = vq->last_avail_idx;
1215         if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) {
1216                 vq_err(vq, "Failed to access avail idx at %p\n",
1217                        &vq->avail->idx);
1218                 return -EFAULT;
1219         }
1220
1221         if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1222                 vq_err(vq, "Guest moved used index from %u to %u",
1223                        last_avail_idx, vq->avail_idx);
1224                 return -EFAULT;
1225         }
1226
1227         /* If there's nothing new since last we looked, return invalid. */
1228         if (vq->avail_idx == last_avail_idx)
1229                 return vq->num;
1230
1231         /* Only get avail ring entries after they have been exposed by guest. */
1232         smp_rmb();
1233
1234         /* Grab the next descriptor number they're advertising, and increment
1235          * the index we've seen. */
1236         if (unlikely(__get_user(head,
1237                                 &vq->avail->ring[last_avail_idx % vq->num]))) {
1238                 vq_err(vq, "Failed to read head: idx %d address %p\n",
1239                        last_avail_idx,
1240                        &vq->avail->ring[last_avail_idx % vq->num]);
1241                 return -EFAULT;
1242         }
1243
1244         /* If their number is silly, that's an error. */
1245         if (unlikely(head >= vq->num)) {
1246                 vq_err(vq, "Guest says index %u > %u is available",
1247                        head, vq->num);
1248                 return -EINVAL;
1249         }
1250
1251         /* When we start there are none of either input nor output. */
1252         *out_num = *in_num = 0;
1253         if (unlikely(log))
1254                 *log_num = 0;
1255
1256         i = head;
1257         do {
1258                 unsigned iov_count = *in_num + *out_num;
1259                 if (unlikely(i >= vq->num)) {
1260                         vq_err(vq, "Desc index is %u > %u, head = %u",
1261                                i, vq->num, head);
1262                         return -EINVAL;
1263                 }
1264                 if (unlikely(++found > vq->num)) {
1265                         vq_err(vq, "Loop detected: last one at %u "
1266                                "vq size %u head %u\n",
1267                                i, vq->num, head);
1268                         return -EINVAL;
1269                 }
1270                 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1271                 if (unlikely(ret)) {
1272                         vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1273                                i, vq->desc + i);
1274                         return -EFAULT;
1275                 }
1276                 if (desc.flags & VRING_DESC_F_INDIRECT) {
1277                         ret = get_indirect(dev, vq, iov, iov_size,
1278                                            out_num, in_num,
1279                                            log, log_num, &desc);
1280                         if (unlikely(ret < 0)) {
1281                                 vq_err(vq, "Failure detected "
1282                                        "in indirect descriptor at idx %d\n", i);
1283                                 return ret;
1284                         }
1285                         continue;
1286                 }
1287
1288                 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1289                                      iov_size - iov_count);
1290                 if (unlikely(ret < 0)) {
1291                         vq_err(vq, "Translation failure %d descriptor idx %d\n",
1292                                ret, i);
1293                         return ret;
1294                 }
1295                 if (desc.flags & VRING_DESC_F_WRITE) {
1296                         /* If this is an input descriptor,
1297                          * increment that count. */
1298                         *in_num += ret;
1299                         if (unlikely(log)) {
1300                                 log[*log_num].addr = desc.addr;
1301                                 log[*log_num].len = desc.len;
1302                                 ++*log_num;
1303                         }
1304                 } else {
1305                         /* If it's an output descriptor, they're all supposed
1306                          * to come before any input descriptors. */
1307                         if (unlikely(*in_num)) {
1308                                 vq_err(vq, "Descriptor has out after in: "
1309                                        "idx %d\n", i);
1310                                 return -EINVAL;
1311                         }
1312                         *out_num += ret;
1313                 }
1314         } while ((i = next_desc(&desc)) != -1);
1315
1316         /* On success, increment avail index. */
1317         vq->last_avail_idx++;
1318
1319         /* Assume notifications from guest are disabled at this point,
1320          * if they aren't we would need to update avail_event index. */
1321         BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1322         return head;
1323 }
1324
1325 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1326 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1327 {
1328         vq->last_avail_idx -= n;
1329 }
1330
1331 /* After we've used one of their buffers, we tell them about it.  We'll then
1332  * want to notify the guest, using eventfd. */
1333 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1334 {
1335         struct vring_used_elem __user *used;
1336
1337         /* The virtqueue contains a ring of used buffers.  Get a pointer to the
1338          * next entry in that used ring. */
1339         used = &vq->used->ring[vq->last_used_idx % vq->num];
1340         if (__put_user(head, &used->id)) {
1341                 vq_err(vq, "Failed to write used id");
1342                 return -EFAULT;
1343         }
1344         if (__put_user(len, &used->len)) {
1345                 vq_err(vq, "Failed to write used len");
1346                 return -EFAULT;
1347         }
1348         /* Make sure buffer is written before we update index. */
1349         smp_wmb();
1350         if (__put_user(vq->last_used_idx + 1, &vq->used->idx)) {
1351                 vq_err(vq, "Failed to increment used idx");
1352                 return -EFAULT;
1353         }
1354         if (unlikely(vq->log_used)) {
1355                 /* Make sure data is seen before log. */
1356                 smp_wmb();
1357                 /* Log used ring entry write. */
1358                 log_write(vq->log_base,
1359                           vq->log_addr +
1360                            ((void __user *)used - (void __user *)vq->used),
1361                           sizeof *used);
1362                 /* Log used index update. */
1363                 log_write(vq->log_base,
1364                           vq->log_addr + offsetof(struct vring_used, idx),
1365                           sizeof vq->used->idx);
1366                 if (vq->log_ctx)
1367                         eventfd_signal(vq->log_ctx, 1);
1368         }
1369         vq->last_used_idx++;
1370         /* If the driver never bothers to signal in a very long while,
1371          * used index might wrap around. If that happens, invalidate
1372          * signalled_used index we stored. TODO: make sure driver
1373          * signals at least once in 2^16 and remove this. */
1374         if (unlikely(vq->last_used_idx == vq->signalled_used))
1375                 vq->signalled_used_valid = false;
1376         return 0;
1377 }
1378
1379 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1380                             struct vring_used_elem *heads,
1381                             unsigned count)
1382 {
1383         struct vring_used_elem __user *used;
1384         u16 old, new;
1385         int start;
1386
1387         start = vq->last_used_idx % vq->num;
1388         used = vq->used->ring + start;
1389         if (__copy_to_user(used, heads, count * sizeof *used)) {
1390                 vq_err(vq, "Failed to write used");
1391                 return -EFAULT;
1392         }
1393         if (unlikely(vq->log_used)) {
1394                 /* Make sure data is seen before log. */
1395                 smp_wmb();
1396                 /* Log used ring entry write. */
1397                 log_write(vq->log_base,
1398                           vq->log_addr +
1399                            ((void __user *)used - (void __user *)vq->used),
1400                           count * sizeof *used);
1401         }
1402         old = vq->last_used_idx;
1403         new = (vq->last_used_idx += count);
1404         /* If the driver never bothers to signal in a very long while,
1405          * used index might wrap around. If that happens, invalidate
1406          * signalled_used index we stored. TODO: make sure driver
1407          * signals at least once in 2^16 and remove this. */
1408         if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1409                 vq->signalled_used_valid = false;
1410         return 0;
1411 }
1412
1413 /* After we've used one of their buffers, we tell them about it.  We'll then
1414  * want to notify the guest, using eventfd. */
1415 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1416                      unsigned count)
1417 {
1418         int start, n, r;
1419
1420         start = vq->last_used_idx % vq->num;
1421         n = vq->num - start;
1422         if (n < count) {
1423                 r = __vhost_add_used_n(vq, heads, n);
1424                 if (r < 0)
1425                         return r;
1426                 heads += n;
1427                 count -= n;
1428         }
1429         r = __vhost_add_used_n(vq, heads, count);
1430
1431         /* Make sure buffer is written before we update index. */
1432         smp_wmb();
1433         if (put_user(vq->last_used_idx, &vq->used->idx)) {
1434                 vq_err(vq, "Failed to increment used idx");
1435                 return -EFAULT;
1436         }
1437         if (unlikely(vq->log_used)) {
1438                 /* Log used index update. */
1439                 log_write(vq->log_base,
1440                           vq->log_addr + offsetof(struct vring_used, idx),
1441                           sizeof vq->used->idx);
1442                 if (vq->log_ctx)
1443                         eventfd_signal(vq->log_ctx, 1);
1444         }
1445         return r;
1446 }
1447
1448 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1449 {
1450         __u16 old, new, event;
1451         bool v;
1452         /* Flush out used index updates. This is paired
1453          * with the barrier that the Guest executes when enabling
1454          * interrupts. */
1455         smp_mb();
1456
1457         if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1458             unlikely(vq->avail_idx == vq->last_avail_idx))
1459                 return true;
1460
1461         if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1462                 __u16 flags;
1463                 if (__get_user(flags, &vq->avail->flags)) {
1464                         vq_err(vq, "Failed to get flags");
1465                         return true;
1466                 }
1467                 return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
1468         }
1469         old = vq->signalled_used;
1470         v = vq->signalled_used_valid;
1471         new = vq->signalled_used = vq->last_used_idx;
1472         vq->signalled_used_valid = true;
1473
1474         if (unlikely(!v))
1475                 return true;
1476
1477         if (get_user(event, vhost_used_event(vq))) {
1478                 vq_err(vq, "Failed to get used event idx");
1479                 return true;
1480         }
1481         return vring_need_event(event, new, old);
1482 }
1483
1484 /* This actually signals the guest, using eventfd. */
1485 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1486 {
1487         /* Signal the Guest tell them we used something up. */
1488         if (vq->call_ctx && vhost_notify(dev, vq))
1489                 eventfd_signal(vq->call_ctx, 1);
1490 }
1491
1492 /* And here's the combo meal deal.  Supersize me! */
1493 void vhost_add_used_and_signal(struct vhost_dev *dev,
1494                                struct vhost_virtqueue *vq,
1495                                unsigned int head, int len)
1496 {
1497         vhost_add_used(vq, head, len);
1498         vhost_signal(dev, vq);
1499 }
1500
1501 /* multi-buffer version of vhost_add_used_and_signal */
1502 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1503                                  struct vhost_virtqueue *vq,
1504                                  struct vring_used_elem *heads, unsigned count)
1505 {
1506         vhost_add_used_n(vq, heads, count);
1507         vhost_signal(dev, vq);
1508 }
1509
1510 /* OK, now we need to know about added descriptors. */
1511 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1512 {
1513         u16 avail_idx;
1514         int r;
1515
1516         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1517                 return false;
1518         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1519         if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1520                 r = vhost_update_used_flags(vq);
1521                 if (r) {
1522                         vq_err(vq, "Failed to enable notification at %p: %d\n",
1523                                &vq->used->flags, r);
1524                         return false;
1525                 }
1526         } else {
1527                 r = vhost_update_avail_event(vq, vq->avail_idx);
1528                 if (r) {
1529                         vq_err(vq, "Failed to update avail event index at %p: %d\n",
1530                                vhost_avail_event(vq), r);
1531                         return false;
1532                 }
1533         }
1534         /* They could have slipped one in as we were doing that: make
1535          * sure it's written, then check again. */
1536         smp_mb();
1537         r = __get_user(avail_idx, &vq->avail->idx);
1538         if (r) {
1539                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1540                        &vq->avail->idx, r);
1541                 return false;
1542         }
1543
1544         return avail_idx != vq->avail_idx;
1545 }
1546
1547 /* We don't need to be notified again. */
1548 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1549 {
1550         int r;
1551
1552         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1553                 return;
1554         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1555         if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1556                 r = vhost_update_used_flags(vq);
1557                 if (r)
1558                         vq_err(vq, "Failed to enable notification at %p: %d\n",
1559                                &vq->used->flags, r);
1560         }
1561 }
1562
1563 static void vhost_zerocopy_done_signal(struct kref *kref)
1564 {
1565         struct vhost_ubuf_ref *ubufs = container_of(kref, struct vhost_ubuf_ref,
1566                                                     kref);
1567         wake_up(&ubufs->wait);
1568 }
1569
1570 struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *vq,
1571                                         bool zcopy)
1572 {
1573         struct vhost_ubuf_ref *ubufs;
1574         /* No zero copy backend? Nothing to count. */
1575         if (!zcopy)
1576                 return NULL;
1577         ubufs = kmalloc(sizeof *ubufs, GFP_KERNEL);
1578         if (!ubufs)
1579                 return ERR_PTR(-ENOMEM);
1580         kref_init(&ubufs->kref);
1581         init_waitqueue_head(&ubufs->wait);
1582         ubufs->vq = vq;
1583         return ubufs;
1584 }
1585
1586 void vhost_ubuf_put(struct vhost_ubuf_ref *ubufs)
1587 {
1588         kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1589 }
1590
1591 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *ubufs)
1592 {
1593         kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1594         wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount));
1595         kfree(ubufs);
1596 }
1597
1598 void vhost_zerocopy_callback(void *arg)
1599 {
1600         struct ubuf_info *ubuf = arg;
1601         struct vhost_ubuf_ref *ubufs = ubuf->arg;
1602         struct vhost_virtqueue *vq = ubufs->vq;
1603
1604         /* set len = 1 to mark this desc buffers done DMA */
1605         vq->heads[ubuf->desc].len = VHOST_DMA_DONE_LEN;
1606         kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1607 }