Linux 3.9-rc4
[linux-2.6/cjktty.git] / drivers / vhost / vhost.c
blob9759249e6d908867cf72f53e5bb8e4ecc30db8ae
1 /* Copyright (C) 2009 Red Hat, Inc.
2 * Copyright (C) 2006 Rusty Russell IBM Corporation
4 * Author: Michael S. Tsirkin <mst@redhat.com>
6 * Inspiration, some code, and most witty comments come from
7 * Documentation/virtual/lguest/lguest.c, by Rusty Russell
9 * This work is licensed under the terms of the GNU GPL, version 2.
11 * Generic code for virtio server in host kernel.
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>
29 #include "vhost.h"
31 enum {
32 VHOST_MEMORY_MAX_NREGIONS = 64,
33 VHOST_MEMORY_F_LOG = 0x1,
36 static unsigned vhost_zcopy_mask __read_mostly;
38 #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
39 #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
41 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
42 poll_table *pt)
44 struct vhost_poll *poll;
46 poll = container_of(pt, struct vhost_poll, table);
47 poll->wqh = wqh;
48 add_wait_queue(wqh, &poll->wait);
51 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
52 void *key)
54 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
56 if (!((unsigned long)key & poll->mask))
57 return 0;
59 vhost_poll_queue(poll);
60 return 0;
63 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
65 INIT_LIST_HEAD(&work->node);
66 work->fn = fn;
67 init_waitqueue_head(&work->done);
68 work->flushing = 0;
69 work->queue_seq = work->done_seq = 0;
72 /* Init poll structure */
73 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
74 unsigned long mask, struct vhost_dev *dev)
76 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
77 init_poll_funcptr(&poll->table, vhost_poll_func);
78 poll->mask = mask;
79 poll->dev = dev;
80 poll->wqh = NULL;
82 vhost_work_init(&poll->work, fn);
85 /* Start polling a file. We add ourselves to file's wait queue. The caller must
86 * keep a reference to a file until after vhost_poll_stop is called. */
87 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
89 unsigned long mask;
90 int ret = 0;
92 mask = file->f_op->poll(file, &poll->table);
93 if (mask)
94 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
95 if (mask & POLLERR) {
96 if (poll->wqh)
97 remove_wait_queue(poll->wqh, &poll->wait);
98 ret = -EINVAL;
101 return ret;
104 /* Stop polling a file. After this function returns, it becomes safe to drop the
105 * file reference. You must also flush afterwards. */
106 void vhost_poll_stop(struct vhost_poll *poll)
108 if (poll->wqh) {
109 remove_wait_queue(poll->wqh, &poll->wait);
110 poll->wqh = NULL;
114 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
115 unsigned seq)
117 int left;
119 spin_lock_irq(&dev->work_lock);
120 left = seq - work->done_seq;
121 spin_unlock_irq(&dev->work_lock);
122 return left <= 0;
125 static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
127 unsigned seq;
128 int flushing;
130 spin_lock_irq(&dev->work_lock);
131 seq = work->queue_seq;
132 work->flushing++;
133 spin_unlock_irq(&dev->work_lock);
134 wait_event(work->done, vhost_work_seq_done(dev, work, seq));
135 spin_lock_irq(&dev->work_lock);
136 flushing = --work->flushing;
137 spin_unlock_irq(&dev->work_lock);
138 BUG_ON(flushing < 0);
141 /* Flush any work that has been scheduled. When calling this, don't hold any
142 * locks that are also used by the callback. */
143 void vhost_poll_flush(struct vhost_poll *poll)
145 vhost_work_flush(poll->dev, &poll->work);
148 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
150 unsigned long flags;
152 spin_lock_irqsave(&dev->work_lock, flags);
153 if (list_empty(&work->node)) {
154 list_add_tail(&work->node, &dev->work_list);
155 work->queue_seq++;
156 wake_up_process(dev->worker);
158 spin_unlock_irqrestore(&dev->work_lock, flags);
161 void vhost_poll_queue(struct vhost_poll *poll)
163 vhost_work_queue(poll->dev, &poll->work);
166 static void vhost_vq_reset(struct vhost_dev *dev,
167 struct vhost_virtqueue *vq)
169 vq->num = 1;
170 vq->desc = NULL;
171 vq->avail = NULL;
172 vq->used = NULL;
173 vq->last_avail_idx = 0;
174 vq->avail_idx = 0;
175 vq->last_used_idx = 0;
176 vq->signalled_used = 0;
177 vq->signalled_used_valid = false;
178 vq->used_flags = 0;
179 vq->log_used = false;
180 vq->log_addr = -1ull;
181 vq->vhost_hlen = 0;
182 vq->sock_hlen = 0;
183 vq->private_data = NULL;
184 vq->log_base = NULL;
185 vq->error_ctx = NULL;
186 vq->error = NULL;
187 vq->kick = NULL;
188 vq->call_ctx = NULL;
189 vq->call = NULL;
190 vq->log_ctx = NULL;
191 vq->upend_idx = 0;
192 vq->done_idx = 0;
193 vq->ubufs = NULL;
196 static int vhost_worker(void *data)
198 struct vhost_dev *dev = data;
199 struct vhost_work *work = NULL;
200 unsigned uninitialized_var(seq);
201 mm_segment_t oldfs = get_fs();
203 set_fs(USER_DS);
204 use_mm(dev->mm);
206 for (;;) {
207 /* mb paired w/ kthread_stop */
208 set_current_state(TASK_INTERRUPTIBLE);
210 spin_lock_irq(&dev->work_lock);
211 if (work) {
212 work->done_seq = seq;
213 if (work->flushing)
214 wake_up_all(&work->done);
217 if (kthread_should_stop()) {
218 spin_unlock_irq(&dev->work_lock);
219 __set_current_state(TASK_RUNNING);
220 break;
222 if (!list_empty(&dev->work_list)) {
223 work = list_first_entry(&dev->work_list,
224 struct vhost_work, node);
225 list_del_init(&work->node);
226 seq = work->queue_seq;
227 } else
228 work = NULL;
229 spin_unlock_irq(&dev->work_lock);
231 if (work) {
232 __set_current_state(TASK_RUNNING);
233 work->fn(work);
234 if (need_resched())
235 schedule();
236 } else
237 schedule();
240 unuse_mm(dev->mm);
241 set_fs(oldfs);
242 return 0;
245 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
247 kfree(vq->indirect);
248 vq->indirect = NULL;
249 kfree(vq->log);
250 vq->log = NULL;
251 kfree(vq->heads);
252 vq->heads = NULL;
253 kfree(vq->ubuf_info);
254 vq->ubuf_info = NULL;
257 void vhost_enable_zcopy(int vq)
259 vhost_zcopy_mask |= 0x1 << vq;
262 /* Helper to allocate iovec buffers for all vqs. */
263 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
265 int i;
266 bool zcopy;
268 for (i = 0; i < dev->nvqs; ++i) {
269 dev->vqs[i].indirect = kmalloc(sizeof *dev->vqs[i].indirect *
270 UIO_MAXIOV, GFP_KERNEL);
271 dev->vqs[i].log = kmalloc(sizeof *dev->vqs[i].log * UIO_MAXIOV,
272 GFP_KERNEL);
273 dev->vqs[i].heads = kmalloc(sizeof *dev->vqs[i].heads *
274 UIO_MAXIOV, GFP_KERNEL);
275 zcopy = vhost_zcopy_mask & (0x1 << i);
276 if (zcopy)
277 dev->vqs[i].ubuf_info =
278 kmalloc(sizeof *dev->vqs[i].ubuf_info *
279 UIO_MAXIOV, GFP_KERNEL);
280 if (!dev->vqs[i].indirect || !dev->vqs[i].log ||
281 !dev->vqs[i].heads ||
282 (zcopy && !dev->vqs[i].ubuf_info))
283 goto err_nomem;
285 return 0;
287 err_nomem:
288 for (; i >= 0; --i)
289 vhost_vq_free_iovecs(&dev->vqs[i]);
290 return -ENOMEM;
293 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
295 int i;
297 for (i = 0; i < dev->nvqs; ++i)
298 vhost_vq_free_iovecs(&dev->vqs[i]);
301 long vhost_dev_init(struct vhost_dev *dev,
302 struct vhost_virtqueue *vqs, int nvqs)
304 int i;
306 dev->vqs = vqs;
307 dev->nvqs = nvqs;
308 mutex_init(&dev->mutex);
309 dev->log_ctx = NULL;
310 dev->log_file = NULL;
311 dev->memory = NULL;
312 dev->mm = NULL;
313 spin_lock_init(&dev->work_lock);
314 INIT_LIST_HEAD(&dev->work_list);
315 dev->worker = NULL;
317 for (i = 0; i < dev->nvqs; ++i) {
318 dev->vqs[i].log = NULL;
319 dev->vqs[i].indirect = NULL;
320 dev->vqs[i].heads = NULL;
321 dev->vqs[i].ubuf_info = NULL;
322 dev->vqs[i].dev = dev;
323 mutex_init(&dev->vqs[i].mutex);
324 vhost_vq_reset(dev, dev->vqs + i);
325 if (dev->vqs[i].handle_kick)
326 vhost_poll_init(&dev->vqs[i].poll,
327 dev->vqs[i].handle_kick, POLLIN, dev);
330 return 0;
333 /* Caller should have device mutex */
334 long vhost_dev_check_owner(struct vhost_dev *dev)
336 /* Are you the owner? If not, I don't think you mean to do that */
337 return dev->mm == current->mm ? 0 : -EPERM;
340 struct vhost_attach_cgroups_struct {
341 struct vhost_work work;
342 struct task_struct *owner;
343 int ret;
346 static void vhost_attach_cgroups_work(struct vhost_work *work)
348 struct vhost_attach_cgroups_struct *s;
350 s = container_of(work, struct vhost_attach_cgroups_struct, work);
351 s->ret = cgroup_attach_task_all(s->owner, current);
354 static int vhost_attach_cgroups(struct vhost_dev *dev)
356 struct vhost_attach_cgroups_struct attach;
358 attach.owner = current;
359 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
360 vhost_work_queue(dev, &attach.work);
361 vhost_work_flush(dev, &attach.work);
362 return attach.ret;
365 /* Caller should have device mutex */
366 static long vhost_dev_set_owner(struct vhost_dev *dev)
368 struct task_struct *worker;
369 int err;
371 /* Is there an owner already? */
372 if (dev->mm) {
373 err = -EBUSY;
374 goto err_mm;
377 /* No owner, become one */
378 dev->mm = get_task_mm(current);
379 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
380 if (IS_ERR(worker)) {
381 err = PTR_ERR(worker);
382 goto err_worker;
385 dev->worker = worker;
386 wake_up_process(worker); /* avoid contributing to loadavg */
388 err = vhost_attach_cgroups(dev);
389 if (err)
390 goto err_cgroup;
392 err = vhost_dev_alloc_iovecs(dev);
393 if (err)
394 goto err_cgroup;
396 return 0;
397 err_cgroup:
398 kthread_stop(worker);
399 dev->worker = NULL;
400 err_worker:
401 if (dev->mm)
402 mmput(dev->mm);
403 dev->mm = NULL;
404 err_mm:
405 return err;
408 /* Caller should have device mutex */
409 long vhost_dev_reset_owner(struct vhost_dev *dev)
411 struct vhost_memory *memory;
413 /* Restore memory to default empty mapping. */
414 memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
415 if (!memory)
416 return -ENOMEM;
418 vhost_dev_cleanup(dev, true);
420 memory->nregions = 0;
421 RCU_INIT_POINTER(dev->memory, memory);
422 return 0;
425 void vhost_dev_stop(struct vhost_dev *dev)
427 int i;
429 for (i = 0; i < dev->nvqs; ++i) {
430 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) {
431 vhost_poll_stop(&dev->vqs[i].poll);
432 vhost_poll_flush(&dev->vqs[i].poll);
437 /* Caller should have device mutex if and only if locked is set */
438 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
440 int i;
442 for (i = 0; i < dev->nvqs; ++i) {
443 if (dev->vqs[i].error_ctx)
444 eventfd_ctx_put(dev->vqs[i].error_ctx);
445 if (dev->vqs[i].error)
446 fput(dev->vqs[i].error);
447 if (dev->vqs[i].kick)
448 fput(dev->vqs[i].kick);
449 if (dev->vqs[i].call_ctx)
450 eventfd_ctx_put(dev->vqs[i].call_ctx);
451 if (dev->vqs[i].call)
452 fput(dev->vqs[i].call);
453 vhost_vq_reset(dev, dev->vqs + i);
455 vhost_dev_free_iovecs(dev);
456 if (dev->log_ctx)
457 eventfd_ctx_put(dev->log_ctx);
458 dev->log_ctx = NULL;
459 if (dev->log_file)
460 fput(dev->log_file);
461 dev->log_file = NULL;
462 /* No one will access memory at this point */
463 kfree(rcu_dereference_protected(dev->memory,
464 locked ==
465 lockdep_is_held(&dev->mutex)));
466 RCU_INIT_POINTER(dev->memory, NULL);
467 WARN_ON(!list_empty(&dev->work_list));
468 if (dev->worker) {
469 kthread_stop(dev->worker);
470 dev->worker = NULL;
472 if (dev->mm)
473 mmput(dev->mm);
474 dev->mm = NULL;
477 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
479 u64 a = addr / VHOST_PAGE_SIZE / 8;
481 /* Make sure 64 bit math will not overflow. */
482 if (a > ULONG_MAX - (unsigned long)log_base ||
483 a + (unsigned long)log_base > ULONG_MAX)
484 return 0;
486 return access_ok(VERIFY_WRITE, log_base + a,
487 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
490 /* Caller should have vq mutex and device mutex. */
491 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
492 int log_all)
494 int i;
496 if (!mem)
497 return 0;
499 for (i = 0; i < mem->nregions; ++i) {
500 struct vhost_memory_region *m = mem->regions + i;
501 unsigned long a = m->userspace_addr;
502 if (m->memory_size > ULONG_MAX)
503 return 0;
504 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
505 m->memory_size))
506 return 0;
507 else if (log_all && !log_access_ok(log_base,
508 m->guest_phys_addr,
509 m->memory_size))
510 return 0;
512 return 1;
515 /* Can we switch to this memory table? */
516 /* Caller should have device mutex but not vq mutex */
517 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
518 int log_all)
520 int i;
522 for (i = 0; i < d->nvqs; ++i) {
523 int ok;
524 mutex_lock(&d->vqs[i].mutex);
525 /* If ring is inactive, will check when it's enabled. */
526 if (d->vqs[i].private_data)
527 ok = vq_memory_access_ok(d->vqs[i].log_base, mem,
528 log_all);
529 else
530 ok = 1;
531 mutex_unlock(&d->vqs[i].mutex);
532 if (!ok)
533 return 0;
535 return 1;
538 static int vq_access_ok(struct vhost_dev *d, unsigned int num,
539 struct vring_desc __user *desc,
540 struct vring_avail __user *avail,
541 struct vring_used __user *used)
543 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
544 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
545 access_ok(VERIFY_READ, avail,
546 sizeof *avail + num * sizeof *avail->ring + s) &&
547 access_ok(VERIFY_WRITE, used,
548 sizeof *used + num * sizeof *used->ring + s);
551 /* Can we log writes? */
552 /* Caller should have device mutex but not vq mutex */
553 int vhost_log_access_ok(struct vhost_dev *dev)
555 struct vhost_memory *mp;
557 mp = rcu_dereference_protected(dev->memory,
558 lockdep_is_held(&dev->mutex));
559 return memory_access_ok(dev, mp, 1);
562 /* Verify access for write logging. */
563 /* Caller should have vq mutex and device mutex */
564 static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
565 void __user *log_base)
567 struct vhost_memory *mp;
568 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
570 mp = rcu_dereference_protected(vq->dev->memory,
571 lockdep_is_held(&vq->mutex));
572 return vq_memory_access_ok(log_base, mp,
573 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
574 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
575 sizeof *vq->used +
576 vq->num * sizeof *vq->used->ring + s));
579 /* Can we start vq? */
580 /* Caller should have vq mutex and device mutex */
581 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
583 return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
584 vq_log_access_ok(vq->dev, vq, vq->log_base);
587 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
589 struct vhost_memory mem, *newmem, *oldmem;
590 unsigned long size = offsetof(struct vhost_memory, regions);
592 if (copy_from_user(&mem, m, size))
593 return -EFAULT;
594 if (mem.padding)
595 return -EOPNOTSUPP;
596 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
597 return -E2BIG;
598 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL);
599 if (!newmem)
600 return -ENOMEM;
602 memcpy(newmem, &mem, size);
603 if (copy_from_user(newmem->regions, m->regions,
604 mem.nregions * sizeof *m->regions)) {
605 kfree(newmem);
606 return -EFAULT;
609 if (!memory_access_ok(d, newmem,
610 vhost_has_feature(d, VHOST_F_LOG_ALL))) {
611 kfree(newmem);
612 return -EFAULT;
614 oldmem = rcu_dereference_protected(d->memory,
615 lockdep_is_held(&d->mutex));
616 rcu_assign_pointer(d->memory, newmem);
617 synchronize_rcu();
618 kfree(oldmem);
619 return 0;
622 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
624 struct file *eventfp, *filep = NULL;
625 bool pollstart = false, pollstop = false;
626 struct eventfd_ctx *ctx = NULL;
627 u32 __user *idxp = argp;
628 struct vhost_virtqueue *vq;
629 struct vhost_vring_state s;
630 struct vhost_vring_file f;
631 struct vhost_vring_addr a;
632 u32 idx;
633 long r;
635 r = get_user(idx, idxp);
636 if (r < 0)
637 return r;
638 if (idx >= d->nvqs)
639 return -ENOBUFS;
641 vq = d->vqs + idx;
643 mutex_lock(&vq->mutex);
645 switch (ioctl) {
646 case VHOST_SET_VRING_NUM:
647 /* Resizing ring with an active backend?
648 * You don't want to do that. */
649 if (vq->private_data) {
650 r = -EBUSY;
651 break;
653 if (copy_from_user(&s, argp, sizeof s)) {
654 r = -EFAULT;
655 break;
657 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
658 r = -EINVAL;
659 break;
661 vq->num = s.num;
662 break;
663 case VHOST_SET_VRING_BASE:
664 /* Moving base with an active backend?
665 * You don't want to do that. */
666 if (vq->private_data) {
667 r = -EBUSY;
668 break;
670 if (copy_from_user(&s, argp, sizeof s)) {
671 r = -EFAULT;
672 break;
674 if (s.num > 0xffff) {
675 r = -EINVAL;
676 break;
678 vq->last_avail_idx = s.num;
679 /* Forget the cached index value. */
680 vq->avail_idx = vq->last_avail_idx;
681 break;
682 case VHOST_GET_VRING_BASE:
683 s.index = idx;
684 s.num = vq->last_avail_idx;
685 if (copy_to_user(argp, &s, sizeof s))
686 r = -EFAULT;
687 break;
688 case VHOST_SET_VRING_ADDR:
689 if (copy_from_user(&a, argp, sizeof a)) {
690 r = -EFAULT;
691 break;
693 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
694 r = -EOPNOTSUPP;
695 break;
697 /* For 32bit, verify that the top 32bits of the user
698 data are set to zero. */
699 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
700 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
701 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
702 r = -EFAULT;
703 break;
705 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
706 (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
707 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
708 r = -EINVAL;
709 break;
712 /* We only verify access here if backend is configured.
713 * If it is not, we don't as size might not have been setup.
714 * We will verify when backend is configured. */
715 if (vq->private_data) {
716 if (!vq_access_ok(d, vq->num,
717 (void __user *)(unsigned long)a.desc_user_addr,
718 (void __user *)(unsigned long)a.avail_user_addr,
719 (void __user *)(unsigned long)a.used_user_addr)) {
720 r = -EINVAL;
721 break;
724 /* Also validate log access for used ring if enabled. */
725 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
726 !log_access_ok(vq->log_base, a.log_guest_addr,
727 sizeof *vq->used +
728 vq->num * sizeof *vq->used->ring)) {
729 r = -EINVAL;
730 break;
734 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
735 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
736 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
737 vq->log_addr = a.log_guest_addr;
738 vq->used = (void __user *)(unsigned long)a.used_user_addr;
739 break;
740 case VHOST_SET_VRING_KICK:
741 if (copy_from_user(&f, argp, sizeof f)) {
742 r = -EFAULT;
743 break;
745 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
746 if (IS_ERR(eventfp)) {
747 r = PTR_ERR(eventfp);
748 break;
750 if (eventfp != vq->kick) {
751 pollstop = (filep = vq->kick) != NULL;
752 pollstart = (vq->kick = eventfp) != NULL;
753 } else
754 filep = eventfp;
755 break;
756 case VHOST_SET_VRING_CALL:
757 if (copy_from_user(&f, argp, sizeof f)) {
758 r = -EFAULT;
759 break;
761 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
762 if (IS_ERR(eventfp)) {
763 r = PTR_ERR(eventfp);
764 break;
766 if (eventfp != vq->call) {
767 filep = vq->call;
768 ctx = vq->call_ctx;
769 vq->call = eventfp;
770 vq->call_ctx = eventfp ?
771 eventfd_ctx_fileget(eventfp) : NULL;
772 } else
773 filep = eventfp;
774 break;
775 case VHOST_SET_VRING_ERR:
776 if (copy_from_user(&f, argp, sizeof f)) {
777 r = -EFAULT;
778 break;
780 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
781 if (IS_ERR(eventfp)) {
782 r = PTR_ERR(eventfp);
783 break;
785 if (eventfp != vq->error) {
786 filep = vq->error;
787 vq->error = eventfp;
788 ctx = vq->error_ctx;
789 vq->error_ctx = eventfp ?
790 eventfd_ctx_fileget(eventfp) : NULL;
791 } else
792 filep = eventfp;
793 break;
794 default:
795 r = -ENOIOCTLCMD;
798 if (pollstop && vq->handle_kick)
799 vhost_poll_stop(&vq->poll);
801 if (ctx)
802 eventfd_ctx_put(ctx);
803 if (filep)
804 fput(filep);
806 if (pollstart && vq->handle_kick)
807 r = vhost_poll_start(&vq->poll, vq->kick);
809 mutex_unlock(&vq->mutex);
811 if (pollstop && vq->handle_kick)
812 vhost_poll_flush(&vq->poll);
813 return r;
816 /* Caller must have device mutex */
817 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
819 struct file *eventfp, *filep = NULL;
820 struct eventfd_ctx *ctx = NULL;
821 u64 p;
822 long r;
823 int i, fd;
825 /* If you are not the owner, you can become one */
826 if (ioctl == VHOST_SET_OWNER) {
827 r = vhost_dev_set_owner(d);
828 goto done;
831 /* You must be the owner to do anything else */
832 r = vhost_dev_check_owner(d);
833 if (r)
834 goto done;
836 switch (ioctl) {
837 case VHOST_SET_MEM_TABLE:
838 r = vhost_set_memory(d, argp);
839 break;
840 case VHOST_SET_LOG_BASE:
841 if (copy_from_user(&p, argp, sizeof p)) {
842 r = -EFAULT;
843 break;
845 if ((u64)(unsigned long)p != p) {
846 r = -EFAULT;
847 break;
849 for (i = 0; i < d->nvqs; ++i) {
850 struct vhost_virtqueue *vq;
851 void __user *base = (void __user *)(unsigned long)p;
852 vq = d->vqs + i;
853 mutex_lock(&vq->mutex);
854 /* If ring is inactive, will check when it's enabled. */
855 if (vq->private_data && !vq_log_access_ok(d, vq, base))
856 r = -EFAULT;
857 else
858 vq->log_base = base;
859 mutex_unlock(&vq->mutex);
861 break;
862 case VHOST_SET_LOG_FD:
863 r = get_user(fd, (int __user *)argp);
864 if (r < 0)
865 break;
866 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
867 if (IS_ERR(eventfp)) {
868 r = PTR_ERR(eventfp);
869 break;
871 if (eventfp != d->log_file) {
872 filep = d->log_file;
873 ctx = d->log_ctx;
874 d->log_ctx = eventfp ?
875 eventfd_ctx_fileget(eventfp) : NULL;
876 } else
877 filep = eventfp;
878 for (i = 0; i < d->nvqs; ++i) {
879 mutex_lock(&d->vqs[i].mutex);
880 d->vqs[i].log_ctx = d->log_ctx;
881 mutex_unlock(&d->vqs[i].mutex);
883 if (ctx)
884 eventfd_ctx_put(ctx);
885 if (filep)
886 fput(filep);
887 break;
888 default:
889 r = -ENOIOCTLCMD;
890 break;
892 done:
893 return r;
896 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
897 __u64 addr, __u32 len)
899 struct vhost_memory_region *reg;
900 int i;
902 /* linear search is not brilliant, but we really have on the order of 6
903 * regions in practice */
904 for (i = 0; i < mem->nregions; ++i) {
905 reg = mem->regions + i;
906 if (reg->guest_phys_addr <= addr &&
907 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
908 return reg;
910 return NULL;
913 /* TODO: This is really inefficient. We need something like get_user()
914 * (instruction directly accesses the data, with an exception table entry
915 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
917 static int set_bit_to_user(int nr, void __user *addr)
919 unsigned long log = (unsigned long)addr;
920 struct page *page;
921 void *base;
922 int bit = nr + (log % PAGE_SIZE) * 8;
923 int r;
925 r = get_user_pages_fast(log, 1, 1, &page);
926 if (r < 0)
927 return r;
928 BUG_ON(r != 1);
929 base = kmap_atomic(page);
930 set_bit(bit, base);
931 kunmap_atomic(base);
932 set_page_dirty_lock(page);
933 put_page(page);
934 return 0;
937 static int log_write(void __user *log_base,
938 u64 write_address, u64 write_length)
940 u64 write_page = write_address / VHOST_PAGE_SIZE;
941 int r;
943 if (!write_length)
944 return 0;
945 write_length += write_address % VHOST_PAGE_SIZE;
946 for (;;) {
947 u64 base = (u64)(unsigned long)log_base;
948 u64 log = base + write_page / 8;
949 int bit = write_page % 8;
950 if ((u64)(unsigned long)log != log)
951 return -EFAULT;
952 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
953 if (r < 0)
954 return r;
955 if (write_length <= VHOST_PAGE_SIZE)
956 break;
957 write_length -= VHOST_PAGE_SIZE;
958 write_page += 1;
960 return r;
963 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
964 unsigned int log_num, u64 len)
966 int i, r;
968 /* Make sure data written is seen before log. */
969 smp_wmb();
970 for (i = 0; i < log_num; ++i) {
971 u64 l = min(log[i].len, len);
972 r = log_write(vq->log_base, log[i].addr, l);
973 if (r < 0)
974 return r;
975 len -= l;
976 if (!len) {
977 if (vq->log_ctx)
978 eventfd_signal(vq->log_ctx, 1);
979 return 0;
982 /* Length written exceeds what we have stored. This is a bug. */
983 BUG();
984 return 0;
987 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
989 void __user *used;
990 if (__put_user(vq->used_flags, &vq->used->flags) < 0)
991 return -EFAULT;
992 if (unlikely(vq->log_used)) {
993 /* Make sure the flag is seen before log. */
994 smp_wmb();
995 /* Log used flag write. */
996 used = &vq->used->flags;
997 log_write(vq->log_base, vq->log_addr +
998 (used - (void __user *)vq->used),
999 sizeof vq->used->flags);
1000 if (vq->log_ctx)
1001 eventfd_signal(vq->log_ctx, 1);
1003 return 0;
1006 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1008 if (__put_user(vq->avail_idx, vhost_avail_event(vq)))
1009 return -EFAULT;
1010 if (unlikely(vq->log_used)) {
1011 void __user *used;
1012 /* Make sure the event is seen before log. */
1013 smp_wmb();
1014 /* Log avail event write */
1015 used = vhost_avail_event(vq);
1016 log_write(vq->log_base, vq->log_addr +
1017 (used - (void __user *)vq->used),
1018 sizeof *vhost_avail_event(vq));
1019 if (vq->log_ctx)
1020 eventfd_signal(vq->log_ctx, 1);
1022 return 0;
1025 int vhost_init_used(struct vhost_virtqueue *vq)
1027 int r;
1028 if (!vq->private_data)
1029 return 0;
1031 r = vhost_update_used_flags(vq);
1032 if (r)
1033 return r;
1034 vq->signalled_used_valid = false;
1035 return get_user(vq->last_used_idx, &vq->used->idx);
1038 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
1039 struct iovec iov[], int iov_size)
1041 const struct vhost_memory_region *reg;
1042 struct vhost_memory *mem;
1043 struct iovec *_iov;
1044 u64 s = 0;
1045 int ret = 0;
1047 rcu_read_lock();
1049 mem = rcu_dereference(dev->memory);
1050 while ((u64)len > s) {
1051 u64 size;
1052 if (unlikely(ret >= iov_size)) {
1053 ret = -ENOBUFS;
1054 break;
1056 reg = find_region(mem, addr, len);
1057 if (unlikely(!reg)) {
1058 ret = -EFAULT;
1059 break;
1061 _iov = iov + ret;
1062 size = reg->memory_size - addr + reg->guest_phys_addr;
1063 _iov->iov_len = min((u64)len - s, size);
1064 _iov->iov_base = (void __user *)(unsigned long)
1065 (reg->userspace_addr + addr - reg->guest_phys_addr);
1066 s += size;
1067 addr += size;
1068 ++ret;
1071 rcu_read_unlock();
1072 return ret;
1075 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1076 * function returns the next descriptor in the chain,
1077 * or -1U if we're at the end. */
1078 static unsigned next_desc(struct vring_desc *desc)
1080 unsigned int next;
1082 /* If this descriptor says it doesn't chain, we're done. */
1083 if (!(desc->flags & VRING_DESC_F_NEXT))
1084 return -1U;
1086 /* Check they're not leading us off end of descriptors. */
1087 next = desc->next;
1088 /* Make sure compiler knows to grab that: we don't want it changing! */
1089 /* We will use the result as an index in an array, so most
1090 * architectures only need a compiler barrier here. */
1091 read_barrier_depends();
1093 return next;
1096 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1097 struct iovec iov[], unsigned int iov_size,
1098 unsigned int *out_num, unsigned int *in_num,
1099 struct vhost_log *log, unsigned int *log_num,
1100 struct vring_desc *indirect)
1102 struct vring_desc desc;
1103 unsigned int i = 0, count, found = 0;
1104 int ret;
1106 /* Sanity check */
1107 if (unlikely(indirect->len % sizeof desc)) {
1108 vq_err(vq, "Invalid length in indirect descriptor: "
1109 "len 0x%llx not multiple of 0x%zx\n",
1110 (unsigned long long)indirect->len,
1111 sizeof desc);
1112 return -EINVAL;
1115 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect,
1116 UIO_MAXIOV);
1117 if (unlikely(ret < 0)) {
1118 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1119 return ret;
1122 /* We will use the result as an address to read from, so most
1123 * architectures only need a compiler barrier here. */
1124 read_barrier_depends();
1126 count = indirect->len / sizeof desc;
1127 /* Buffers are chained via a 16 bit next field, so
1128 * we can have at most 2^16 of these. */
1129 if (unlikely(count > USHRT_MAX + 1)) {
1130 vq_err(vq, "Indirect buffer length too big: %d\n",
1131 indirect->len);
1132 return -E2BIG;
1135 do {
1136 unsigned iov_count = *in_num + *out_num;
1137 if (unlikely(++found > count)) {
1138 vq_err(vq, "Loop detected: last one at %u "
1139 "indirect size %u\n",
1140 i, count);
1141 return -EINVAL;
1143 if (unlikely(memcpy_fromiovec((unsigned char *)&desc,
1144 vq->indirect, sizeof desc))) {
1145 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1146 i, (size_t)indirect->addr + i * sizeof desc);
1147 return -EINVAL;
1149 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
1150 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1151 i, (size_t)indirect->addr + i * sizeof desc);
1152 return -EINVAL;
1155 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1156 iov_size - iov_count);
1157 if (unlikely(ret < 0)) {
1158 vq_err(vq, "Translation failure %d indirect idx %d\n",
1159 ret, i);
1160 return ret;
1162 /* If this is an input descriptor, increment that count. */
1163 if (desc.flags & VRING_DESC_F_WRITE) {
1164 *in_num += ret;
1165 if (unlikely(log)) {
1166 log[*log_num].addr = desc.addr;
1167 log[*log_num].len = desc.len;
1168 ++*log_num;
1170 } else {
1171 /* If it's an output descriptor, they're all supposed
1172 * to come before any input descriptors. */
1173 if (unlikely(*in_num)) {
1174 vq_err(vq, "Indirect descriptor "
1175 "has out after in: idx %d\n", i);
1176 return -EINVAL;
1178 *out_num += ret;
1180 } while ((i = next_desc(&desc)) != -1);
1181 return 0;
1184 /* This looks in the virtqueue and for the first available buffer, and converts
1185 * it to an iovec for convenient access. Since descriptors consist of some
1186 * number of output then some number of input descriptors, it's actually two
1187 * iovecs, but we pack them into one and note how many of each there were.
1189 * This function returns the descriptor number found, or vq->num (which is
1190 * never a valid descriptor number) if none was found. A negative code is
1191 * returned on error. */
1192 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1193 struct iovec iov[], unsigned int iov_size,
1194 unsigned int *out_num, unsigned int *in_num,
1195 struct vhost_log *log, unsigned int *log_num)
1197 struct vring_desc desc;
1198 unsigned int i, head, found = 0;
1199 u16 last_avail_idx;
1200 int ret;
1202 /* Check it isn't doing very strange things with descriptor numbers. */
1203 last_avail_idx = vq->last_avail_idx;
1204 if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) {
1205 vq_err(vq, "Failed to access avail idx at %p\n",
1206 &vq->avail->idx);
1207 return -EFAULT;
1210 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1211 vq_err(vq, "Guest moved used index from %u to %u",
1212 last_avail_idx, vq->avail_idx);
1213 return -EFAULT;
1216 /* If there's nothing new since last we looked, return invalid. */
1217 if (vq->avail_idx == last_avail_idx)
1218 return vq->num;
1220 /* Only get avail ring entries after they have been exposed by guest. */
1221 smp_rmb();
1223 /* Grab the next descriptor number they're advertising, and increment
1224 * the index we've seen. */
1225 if (unlikely(__get_user(head,
1226 &vq->avail->ring[last_avail_idx % vq->num]))) {
1227 vq_err(vq, "Failed to read head: idx %d address %p\n",
1228 last_avail_idx,
1229 &vq->avail->ring[last_avail_idx % vq->num]);
1230 return -EFAULT;
1233 /* If their number is silly, that's an error. */
1234 if (unlikely(head >= vq->num)) {
1235 vq_err(vq, "Guest says index %u > %u is available",
1236 head, vq->num);
1237 return -EINVAL;
1240 /* When we start there are none of either input nor output. */
1241 *out_num = *in_num = 0;
1242 if (unlikely(log))
1243 *log_num = 0;
1245 i = head;
1246 do {
1247 unsigned iov_count = *in_num + *out_num;
1248 if (unlikely(i >= vq->num)) {
1249 vq_err(vq, "Desc index is %u > %u, head = %u",
1250 i, vq->num, head);
1251 return -EINVAL;
1253 if (unlikely(++found > vq->num)) {
1254 vq_err(vq, "Loop detected: last one at %u "
1255 "vq size %u head %u\n",
1256 i, vq->num, head);
1257 return -EINVAL;
1259 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1260 if (unlikely(ret)) {
1261 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1262 i, vq->desc + i);
1263 return -EFAULT;
1265 if (desc.flags & VRING_DESC_F_INDIRECT) {
1266 ret = get_indirect(dev, vq, iov, iov_size,
1267 out_num, in_num,
1268 log, log_num, &desc);
1269 if (unlikely(ret < 0)) {
1270 vq_err(vq, "Failure detected "
1271 "in indirect descriptor at idx %d\n", i);
1272 return ret;
1274 continue;
1277 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1278 iov_size - iov_count);
1279 if (unlikely(ret < 0)) {
1280 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1281 ret, i);
1282 return ret;
1284 if (desc.flags & VRING_DESC_F_WRITE) {
1285 /* If this is an input descriptor,
1286 * increment that count. */
1287 *in_num += ret;
1288 if (unlikely(log)) {
1289 log[*log_num].addr = desc.addr;
1290 log[*log_num].len = desc.len;
1291 ++*log_num;
1293 } else {
1294 /* If it's an output descriptor, they're all supposed
1295 * to come before any input descriptors. */
1296 if (unlikely(*in_num)) {
1297 vq_err(vq, "Descriptor has out after in: "
1298 "idx %d\n", i);
1299 return -EINVAL;
1301 *out_num += ret;
1303 } while ((i = next_desc(&desc)) != -1);
1305 /* On success, increment avail index. */
1306 vq->last_avail_idx++;
1308 /* Assume notifications from guest are disabled at this point,
1309 * if they aren't we would need to update avail_event index. */
1310 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1311 return head;
1314 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1315 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1317 vq->last_avail_idx -= n;
1320 /* After we've used one of their buffers, we tell them about it. We'll then
1321 * want to notify the guest, using eventfd. */
1322 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1324 struct vring_used_elem __user *used;
1326 /* The virtqueue contains a ring of used buffers. Get a pointer to the
1327 * next entry in that used ring. */
1328 used = &vq->used->ring[vq->last_used_idx % vq->num];
1329 if (__put_user(head, &used->id)) {
1330 vq_err(vq, "Failed to write used id");
1331 return -EFAULT;
1333 if (__put_user(len, &used->len)) {
1334 vq_err(vq, "Failed to write used len");
1335 return -EFAULT;
1337 /* Make sure buffer is written before we update index. */
1338 smp_wmb();
1339 if (__put_user(vq->last_used_idx + 1, &vq->used->idx)) {
1340 vq_err(vq, "Failed to increment used idx");
1341 return -EFAULT;
1343 if (unlikely(vq->log_used)) {
1344 /* Make sure data is seen before log. */
1345 smp_wmb();
1346 /* Log used ring entry write. */
1347 log_write(vq->log_base,
1348 vq->log_addr +
1349 ((void __user *)used - (void __user *)vq->used),
1350 sizeof *used);
1351 /* Log used index update. */
1352 log_write(vq->log_base,
1353 vq->log_addr + offsetof(struct vring_used, idx),
1354 sizeof vq->used->idx);
1355 if (vq->log_ctx)
1356 eventfd_signal(vq->log_ctx, 1);
1358 vq->last_used_idx++;
1359 /* If the driver never bothers to signal in a very long while,
1360 * used index might wrap around. If that happens, invalidate
1361 * signalled_used index we stored. TODO: make sure driver
1362 * signals at least once in 2^16 and remove this. */
1363 if (unlikely(vq->last_used_idx == vq->signalled_used))
1364 vq->signalled_used_valid = false;
1365 return 0;
1368 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1369 struct vring_used_elem *heads,
1370 unsigned count)
1372 struct vring_used_elem __user *used;
1373 u16 old, new;
1374 int start;
1376 start = vq->last_used_idx % vq->num;
1377 used = vq->used->ring + start;
1378 if (__copy_to_user(used, heads, count * sizeof *used)) {
1379 vq_err(vq, "Failed to write used");
1380 return -EFAULT;
1382 if (unlikely(vq->log_used)) {
1383 /* Make sure data is seen before log. */
1384 smp_wmb();
1385 /* Log used ring entry write. */
1386 log_write(vq->log_base,
1387 vq->log_addr +
1388 ((void __user *)used - (void __user *)vq->used),
1389 count * sizeof *used);
1391 old = vq->last_used_idx;
1392 new = (vq->last_used_idx += count);
1393 /* If the driver never bothers to signal in a very long while,
1394 * used index might wrap around. If that happens, invalidate
1395 * signalled_used index we stored. TODO: make sure driver
1396 * signals at least once in 2^16 and remove this. */
1397 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1398 vq->signalled_used_valid = false;
1399 return 0;
1402 /* After we've used one of their buffers, we tell them about it. We'll then
1403 * want to notify the guest, using eventfd. */
1404 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1405 unsigned count)
1407 int start, n, r;
1409 start = vq->last_used_idx % vq->num;
1410 n = vq->num - start;
1411 if (n < count) {
1412 r = __vhost_add_used_n(vq, heads, n);
1413 if (r < 0)
1414 return r;
1415 heads += n;
1416 count -= n;
1418 r = __vhost_add_used_n(vq, heads, count);
1420 /* Make sure buffer is written before we update index. */
1421 smp_wmb();
1422 if (put_user(vq->last_used_idx, &vq->used->idx)) {
1423 vq_err(vq, "Failed to increment used idx");
1424 return -EFAULT;
1426 if (unlikely(vq->log_used)) {
1427 /* Log used index update. */
1428 log_write(vq->log_base,
1429 vq->log_addr + offsetof(struct vring_used, idx),
1430 sizeof vq->used->idx);
1431 if (vq->log_ctx)
1432 eventfd_signal(vq->log_ctx, 1);
1434 return r;
1437 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1439 __u16 old, new, event;
1440 bool v;
1441 /* Flush out used index updates. This is paired
1442 * with the barrier that the Guest executes when enabling
1443 * interrupts. */
1444 smp_mb();
1446 if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1447 unlikely(vq->avail_idx == vq->last_avail_idx))
1448 return true;
1450 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1451 __u16 flags;
1452 if (__get_user(flags, &vq->avail->flags)) {
1453 vq_err(vq, "Failed to get flags");
1454 return true;
1456 return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
1458 old = vq->signalled_used;
1459 v = vq->signalled_used_valid;
1460 new = vq->signalled_used = vq->last_used_idx;
1461 vq->signalled_used_valid = true;
1463 if (unlikely(!v))
1464 return true;
1466 if (get_user(event, vhost_used_event(vq))) {
1467 vq_err(vq, "Failed to get used event idx");
1468 return true;
1470 return vring_need_event(event, new, old);
1473 /* This actually signals the guest, using eventfd. */
1474 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1476 /* Signal the Guest tell them we used something up. */
1477 if (vq->call_ctx && vhost_notify(dev, vq))
1478 eventfd_signal(vq->call_ctx, 1);
1481 /* And here's the combo meal deal. Supersize me! */
1482 void vhost_add_used_and_signal(struct vhost_dev *dev,
1483 struct vhost_virtqueue *vq,
1484 unsigned int head, int len)
1486 vhost_add_used(vq, head, len);
1487 vhost_signal(dev, vq);
1490 /* multi-buffer version of vhost_add_used_and_signal */
1491 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1492 struct vhost_virtqueue *vq,
1493 struct vring_used_elem *heads, unsigned count)
1495 vhost_add_used_n(vq, heads, count);
1496 vhost_signal(dev, vq);
1499 /* OK, now we need to know about added descriptors. */
1500 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1502 u16 avail_idx;
1503 int r;
1505 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1506 return false;
1507 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1508 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1509 r = vhost_update_used_flags(vq);
1510 if (r) {
1511 vq_err(vq, "Failed to enable notification at %p: %d\n",
1512 &vq->used->flags, r);
1513 return false;
1515 } else {
1516 r = vhost_update_avail_event(vq, vq->avail_idx);
1517 if (r) {
1518 vq_err(vq, "Failed to update avail event index at %p: %d\n",
1519 vhost_avail_event(vq), r);
1520 return false;
1523 /* They could have slipped one in as we were doing that: make
1524 * sure it's written, then check again. */
1525 smp_mb();
1526 r = __get_user(avail_idx, &vq->avail->idx);
1527 if (r) {
1528 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1529 &vq->avail->idx, r);
1530 return false;
1533 return avail_idx != vq->avail_idx;
1536 /* We don't need to be notified again. */
1537 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1539 int r;
1541 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1542 return;
1543 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1544 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
1545 r = vhost_update_used_flags(vq);
1546 if (r)
1547 vq_err(vq, "Failed to enable notification at %p: %d\n",
1548 &vq->used->flags, r);
1552 static void vhost_zerocopy_done_signal(struct kref *kref)
1554 struct vhost_ubuf_ref *ubufs = container_of(kref, struct vhost_ubuf_ref,
1555 kref);
1556 wake_up(&ubufs->wait);
1559 struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *vq,
1560 bool zcopy)
1562 struct vhost_ubuf_ref *ubufs;
1563 /* No zero copy backend? Nothing to count. */
1564 if (!zcopy)
1565 return NULL;
1566 ubufs = kmalloc(sizeof *ubufs, GFP_KERNEL);
1567 if (!ubufs)
1568 return ERR_PTR(-ENOMEM);
1569 kref_init(&ubufs->kref);
1570 init_waitqueue_head(&ubufs->wait);
1571 ubufs->vq = vq;
1572 return ubufs;
1575 void vhost_ubuf_put(struct vhost_ubuf_ref *ubufs)
1577 kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1580 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *ubufs)
1582 kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1583 wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount));
1584 kfree(ubufs);