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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
35enum {
36 VHOST_MEMORY_MAX_NREGIONS = 64,
37 VHOST_MEMORY_F_LOG = 0x1,
38};
39
40static 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
45static 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
55static 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
67static 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 */
77void 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. */
90void 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. */
101void vhost_poll_stop(struct vhost_poll *poll)
102{
103 remove_wait_queue(poll->wqh, &poll->wait);
104}
105
106static 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
117static 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. */
135void vhost_poll_flush(struct vhost_poll *poll)
136{
137 vhost_work_flush(poll->dev, &poll->work);
138}
139
140static 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
154void vhost_poll_queue(struct vhost_poll *poll)
155{
156 vhost_work_queue(poll->dev, &poll->work);
157}
158
159static 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
189static 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
233static 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
245void vhost_enable_zcopy(int vq)
246{
247 vhost_zcopy_mask |= 0x1 << vq;
248}
249
250/* Helper to allocate iovec buffers for all vqs. */
251static 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
275err_nomem:
276 for (; i >= 0; --i)
277 vhost_vq_free_iovecs(&dev->vqs[i]);
278 return -ENOMEM;
279}
280
281static 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
289long 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 */
322long 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
328struct vhost_attach_cgroups_struct {
329 struct vhost_work work;
330 struct task_struct *owner;
331 int ret;
332};
333
334static 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
342static 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 */
354static 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;
385err_cgroup:
386 kthread_stop(worker);
387 dev->worker = NULL;
388err_worker:
389 if (dev->mm)
390 mmput(dev->mm);
391 dev->mm = NULL;
392err_mm:
393 return err;
394}
395
396/* Caller should have device mutex */
397long 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 */
418int 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 */
438void 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
487static 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. */
501static 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 */
527static 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
548static 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 */
563int 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 */
574static 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 */
591int 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
597static 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
632static 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 */
827long 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 }
903done:
904 return r;
905}
906
907static 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 */
928static 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
948static 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
974int 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
998static 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
1017static 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
1036int 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
1049static 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. */
1089static 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
1107static 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. */
1203int 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. */
1326void 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. */
1333int 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
1379static 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. */
1415int 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
1448static 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. */
1485void 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! */
1493void 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 */
1502void 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. */
1511bool 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. */
1548void 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
1563static 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
1570struct 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
1586void vhost_ubuf_put(struct vhost_ubuf_ref *ubufs)
1587{
1588 kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
1589}
1590
1591void 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
1598void 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}
1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (C) 2009 Red Hat, Inc.
3 * Copyright (C) 2006 Rusty Russell IBM Corporation
4 *
5 * Author: Michael S. Tsirkin <mst@redhat.com>
6 *
7 * Inspiration, some code, and most witty comments come from
8 * Documentation/virtual/lguest/lguest.c, by Rusty Russell
9 *
10 * Generic code for virtio server in host kernel.
11 */
12
13#include <linux/eventfd.h>
14#include <linux/vhost.h>
15#include <linux/uio.h>
16#include <linux/mm.h>
17#include <linux/miscdevice.h>
18#include <linux/mutex.h>
19#include <linux/poll.h>
20#include <linux/file.h>
21#include <linux/highmem.h>
22#include <linux/slab.h>
23#include <linux/vmalloc.h>
24#include <linux/kthread.h>
25#include <linux/cgroup.h>
26#include <linux/module.h>
27#include <linux/sort.h>
28#include <linux/sched/mm.h>
29#include <linux/sched/signal.h>
30#include <linux/interval_tree_generic.h>
31#include <linux/nospec.h>
32#include <linux/kcov.h>
33
34#include "vhost.h"
35
36static ushort max_mem_regions = 64;
37module_param(max_mem_regions, ushort, 0444);
38MODULE_PARM_DESC(max_mem_regions,
39 "Maximum number of memory regions in memory map. (default: 64)");
40static int max_iotlb_entries = 2048;
41module_param(max_iotlb_entries, int, 0444);
42MODULE_PARM_DESC(max_iotlb_entries,
43 "Maximum number of iotlb entries. (default: 2048)");
44
45enum {
46 VHOST_MEMORY_F_LOG = 0x1,
47};
48
49#define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
50#define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
51
52#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
53static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
54{
55 vq->user_be = !virtio_legacy_is_little_endian();
56}
57
58static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
59{
60 vq->user_be = true;
61}
62
63static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
64{
65 vq->user_be = false;
66}
67
68static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
69{
70 struct vhost_vring_state s;
71
72 if (vq->private_data)
73 return -EBUSY;
74
75 if (copy_from_user(&s, argp, sizeof(s)))
76 return -EFAULT;
77
78 if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
79 s.num != VHOST_VRING_BIG_ENDIAN)
80 return -EINVAL;
81
82 if (s.num == VHOST_VRING_BIG_ENDIAN)
83 vhost_enable_cross_endian_big(vq);
84 else
85 vhost_enable_cross_endian_little(vq);
86
87 return 0;
88}
89
90static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
91 int __user *argp)
92{
93 struct vhost_vring_state s = {
94 .index = idx,
95 .num = vq->user_be
96 };
97
98 if (copy_to_user(argp, &s, sizeof(s)))
99 return -EFAULT;
100
101 return 0;
102}
103
104static void vhost_init_is_le(struct vhost_virtqueue *vq)
105{
106 /* Note for legacy virtio: user_be is initialized at reset time
107 * according to the host endianness. If userspace does not set an
108 * explicit endianness, the default behavior is native endian, as
109 * expected by legacy virtio.
110 */
111 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
112}
113#else
114static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
115{
116}
117
118static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
119{
120 return -ENOIOCTLCMD;
121}
122
123static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
124 int __user *argp)
125{
126 return -ENOIOCTLCMD;
127}
128
129static void vhost_init_is_le(struct vhost_virtqueue *vq)
130{
131 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
132 || virtio_legacy_is_little_endian();
133}
134#endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
135
136static void vhost_reset_is_le(struct vhost_virtqueue *vq)
137{
138 vhost_init_is_le(vq);
139}
140
141struct vhost_flush_struct {
142 struct vhost_work work;
143 struct completion wait_event;
144};
145
146static void vhost_flush_work(struct vhost_work *work)
147{
148 struct vhost_flush_struct *s;
149
150 s = container_of(work, struct vhost_flush_struct, work);
151 complete(&s->wait_event);
152}
153
154static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
155 poll_table *pt)
156{
157 struct vhost_poll *poll;
158
159 poll = container_of(pt, struct vhost_poll, table);
160 poll->wqh = wqh;
161 add_wait_queue(wqh, &poll->wait);
162}
163
164static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
165 void *key)
166{
167 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
168 struct vhost_work *work = &poll->work;
169
170 if (!(key_to_poll(key) & poll->mask))
171 return 0;
172
173 if (!poll->dev->use_worker)
174 work->fn(work);
175 else
176 vhost_poll_queue(poll);
177
178 return 0;
179}
180
181void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
182{
183 clear_bit(VHOST_WORK_QUEUED, &work->flags);
184 work->fn = fn;
185}
186EXPORT_SYMBOL_GPL(vhost_work_init);
187
188/* Init poll structure */
189void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
190 __poll_t mask, struct vhost_dev *dev)
191{
192 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
193 init_poll_funcptr(&poll->table, vhost_poll_func);
194 poll->mask = mask;
195 poll->dev = dev;
196 poll->wqh = NULL;
197
198 vhost_work_init(&poll->work, fn);
199}
200EXPORT_SYMBOL_GPL(vhost_poll_init);
201
202/* Start polling a file. We add ourselves to file's wait queue. The caller must
203 * keep a reference to a file until after vhost_poll_stop is called. */
204int vhost_poll_start(struct vhost_poll *poll, struct file *file)
205{
206 __poll_t mask;
207
208 if (poll->wqh)
209 return 0;
210
211 mask = vfs_poll(file, &poll->table);
212 if (mask)
213 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
214 if (mask & EPOLLERR) {
215 vhost_poll_stop(poll);
216 return -EINVAL;
217 }
218
219 return 0;
220}
221EXPORT_SYMBOL_GPL(vhost_poll_start);
222
223/* Stop polling a file. After this function returns, it becomes safe to drop the
224 * file reference. You must also flush afterwards. */
225void vhost_poll_stop(struct vhost_poll *poll)
226{
227 if (poll->wqh) {
228 remove_wait_queue(poll->wqh, &poll->wait);
229 poll->wqh = NULL;
230 }
231}
232EXPORT_SYMBOL_GPL(vhost_poll_stop);
233
234void vhost_work_dev_flush(struct vhost_dev *dev)
235{
236 struct vhost_flush_struct flush;
237
238 if (dev->worker) {
239 init_completion(&flush.wait_event);
240 vhost_work_init(&flush.work, vhost_flush_work);
241
242 vhost_work_queue(dev, &flush.work);
243 wait_for_completion(&flush.wait_event);
244 }
245}
246EXPORT_SYMBOL_GPL(vhost_work_dev_flush);
247
248/* Flush any work that has been scheduled. When calling this, don't hold any
249 * locks that are also used by the callback. */
250void vhost_poll_flush(struct vhost_poll *poll)
251{
252 vhost_work_dev_flush(poll->dev);
253}
254EXPORT_SYMBOL_GPL(vhost_poll_flush);
255
256void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
257{
258 if (!dev->worker)
259 return;
260
261 if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
262 /* We can only add the work to the list after we're
263 * sure it was not in the list.
264 * test_and_set_bit() implies a memory barrier.
265 */
266 llist_add(&work->node, &dev->work_list);
267 wake_up_process(dev->worker);
268 }
269}
270EXPORT_SYMBOL_GPL(vhost_work_queue);
271
272/* A lockless hint for busy polling code to exit the loop */
273bool vhost_has_work(struct vhost_dev *dev)
274{
275 return !llist_empty(&dev->work_list);
276}
277EXPORT_SYMBOL_GPL(vhost_has_work);
278
279void vhost_poll_queue(struct vhost_poll *poll)
280{
281 vhost_work_queue(poll->dev, &poll->work);
282}
283EXPORT_SYMBOL_GPL(vhost_poll_queue);
284
285static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
286{
287 int j;
288
289 for (j = 0; j < VHOST_NUM_ADDRS; j++)
290 vq->meta_iotlb[j] = NULL;
291}
292
293static void vhost_vq_meta_reset(struct vhost_dev *d)
294{
295 int i;
296
297 for (i = 0; i < d->nvqs; ++i)
298 __vhost_vq_meta_reset(d->vqs[i]);
299}
300
301static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
302{
303 call_ctx->ctx = NULL;
304 memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer));
305}
306
307bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
308{
309 return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
310}
311EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
312
313static void vhost_vq_reset(struct vhost_dev *dev,
314 struct vhost_virtqueue *vq)
315{
316 vq->num = 1;
317 vq->desc = NULL;
318 vq->avail = NULL;
319 vq->used = NULL;
320 vq->last_avail_idx = 0;
321 vq->avail_idx = 0;
322 vq->last_used_idx = 0;
323 vq->signalled_used = 0;
324 vq->signalled_used_valid = false;
325 vq->used_flags = 0;
326 vq->log_used = false;
327 vq->log_addr = -1ull;
328 vq->private_data = NULL;
329 vq->acked_features = 0;
330 vq->acked_backend_features = 0;
331 vq->log_base = NULL;
332 vq->error_ctx = NULL;
333 vq->kick = NULL;
334 vq->log_ctx = NULL;
335 vhost_disable_cross_endian(vq);
336 vhost_reset_is_le(vq);
337 vq->busyloop_timeout = 0;
338 vq->umem = NULL;
339 vq->iotlb = NULL;
340 vhost_vring_call_reset(&vq->call_ctx);
341 __vhost_vq_meta_reset(vq);
342}
343
344static int vhost_worker(void *data)
345{
346 struct vhost_dev *dev = data;
347 struct vhost_work *work, *work_next;
348 struct llist_node *node;
349
350 kthread_use_mm(dev->mm);
351
352 for (;;) {
353 /* mb paired w/ kthread_stop */
354 set_current_state(TASK_INTERRUPTIBLE);
355
356 if (kthread_should_stop()) {
357 __set_current_state(TASK_RUNNING);
358 break;
359 }
360
361 node = llist_del_all(&dev->work_list);
362 if (!node)
363 schedule();
364
365 node = llist_reverse_order(node);
366 /* make sure flag is seen after deletion */
367 smp_wmb();
368 llist_for_each_entry_safe(work, work_next, node, node) {
369 clear_bit(VHOST_WORK_QUEUED, &work->flags);
370 __set_current_state(TASK_RUNNING);
371 kcov_remote_start_common(dev->kcov_handle);
372 work->fn(work);
373 kcov_remote_stop();
374 if (need_resched())
375 schedule();
376 }
377 }
378 kthread_unuse_mm(dev->mm);
379 return 0;
380}
381
382static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
383{
384 kfree(vq->indirect);
385 vq->indirect = NULL;
386 kfree(vq->log);
387 vq->log = NULL;
388 kfree(vq->heads);
389 vq->heads = NULL;
390}
391
392/* Helper to allocate iovec buffers for all vqs. */
393static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
394{
395 struct vhost_virtqueue *vq;
396 int i;
397
398 for (i = 0; i < dev->nvqs; ++i) {
399 vq = dev->vqs[i];
400 vq->indirect = kmalloc_array(UIO_MAXIOV,
401 sizeof(*vq->indirect),
402 GFP_KERNEL);
403 vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
404 GFP_KERNEL);
405 vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
406 GFP_KERNEL);
407 if (!vq->indirect || !vq->log || !vq->heads)
408 goto err_nomem;
409 }
410 return 0;
411
412err_nomem:
413 for (; i >= 0; --i)
414 vhost_vq_free_iovecs(dev->vqs[i]);
415 return -ENOMEM;
416}
417
418static void vhost_dev_free_iovecs(struct vhost_dev *dev)
419{
420 int i;
421
422 for (i = 0; i < dev->nvqs; ++i)
423 vhost_vq_free_iovecs(dev->vqs[i]);
424}
425
426bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
427 int pkts, int total_len)
428{
429 struct vhost_dev *dev = vq->dev;
430
431 if ((dev->byte_weight && total_len >= dev->byte_weight) ||
432 pkts >= dev->weight) {
433 vhost_poll_queue(&vq->poll);
434 return true;
435 }
436
437 return false;
438}
439EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
440
441static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
442 unsigned int num)
443{
444 size_t event __maybe_unused =
445 vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
446
447 return sizeof(*vq->avail) +
448 sizeof(*vq->avail->ring) * num + event;
449}
450
451static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
452 unsigned int num)
453{
454 size_t event __maybe_unused =
455 vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
456
457 return sizeof(*vq->used) +
458 sizeof(*vq->used->ring) * num + event;
459}
460
461static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
462 unsigned int num)
463{
464 return sizeof(*vq->desc) * num;
465}
466
467void vhost_dev_init(struct vhost_dev *dev,
468 struct vhost_virtqueue **vqs, int nvqs,
469 int iov_limit, int weight, int byte_weight,
470 bool use_worker,
471 int (*msg_handler)(struct vhost_dev *dev,
472 struct vhost_iotlb_msg *msg))
473{
474 struct vhost_virtqueue *vq;
475 int i;
476
477 dev->vqs = vqs;
478 dev->nvqs = nvqs;
479 mutex_init(&dev->mutex);
480 dev->log_ctx = NULL;
481 dev->umem = NULL;
482 dev->iotlb = NULL;
483 dev->mm = NULL;
484 dev->worker = NULL;
485 dev->iov_limit = iov_limit;
486 dev->weight = weight;
487 dev->byte_weight = byte_weight;
488 dev->use_worker = use_worker;
489 dev->msg_handler = msg_handler;
490 init_llist_head(&dev->work_list);
491 init_waitqueue_head(&dev->wait);
492 INIT_LIST_HEAD(&dev->read_list);
493 INIT_LIST_HEAD(&dev->pending_list);
494 spin_lock_init(&dev->iotlb_lock);
495
496
497 for (i = 0; i < dev->nvqs; ++i) {
498 vq = dev->vqs[i];
499 vq->log = NULL;
500 vq->indirect = NULL;
501 vq->heads = NULL;
502 vq->dev = dev;
503 mutex_init(&vq->mutex);
504 vhost_vq_reset(dev, vq);
505 if (vq->handle_kick)
506 vhost_poll_init(&vq->poll, vq->handle_kick,
507 EPOLLIN, dev);
508 }
509}
510EXPORT_SYMBOL_GPL(vhost_dev_init);
511
512/* Caller should have device mutex */
513long vhost_dev_check_owner(struct vhost_dev *dev)
514{
515 /* Are you the owner? If not, I don't think you mean to do that */
516 return dev->mm == current->mm ? 0 : -EPERM;
517}
518EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
519
520struct vhost_attach_cgroups_struct {
521 struct vhost_work work;
522 struct task_struct *owner;
523 int ret;
524};
525
526static void vhost_attach_cgroups_work(struct vhost_work *work)
527{
528 struct vhost_attach_cgroups_struct *s;
529
530 s = container_of(work, struct vhost_attach_cgroups_struct, work);
531 s->ret = cgroup_attach_task_all(s->owner, current);
532}
533
534static int vhost_attach_cgroups(struct vhost_dev *dev)
535{
536 struct vhost_attach_cgroups_struct attach;
537
538 attach.owner = current;
539 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
540 vhost_work_queue(dev, &attach.work);
541 vhost_work_dev_flush(dev);
542 return attach.ret;
543}
544
545/* Caller should have device mutex */
546bool vhost_dev_has_owner(struct vhost_dev *dev)
547{
548 return dev->mm;
549}
550EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
551
552static void vhost_attach_mm(struct vhost_dev *dev)
553{
554 /* No owner, become one */
555 if (dev->use_worker) {
556 dev->mm = get_task_mm(current);
557 } else {
558 /* vDPA device does not use worker thead, so there's
559 * no need to hold the address space for mm. This help
560 * to avoid deadlock in the case of mmap() which may
561 * held the refcnt of the file and depends on release
562 * method to remove vma.
563 */
564 dev->mm = current->mm;
565 mmgrab(dev->mm);
566 }
567}
568
569static void vhost_detach_mm(struct vhost_dev *dev)
570{
571 if (!dev->mm)
572 return;
573
574 if (dev->use_worker)
575 mmput(dev->mm);
576 else
577 mmdrop(dev->mm);
578
579 dev->mm = NULL;
580}
581
582/* Caller should have device mutex */
583long vhost_dev_set_owner(struct vhost_dev *dev)
584{
585 struct task_struct *worker;
586 int err;
587
588 /* Is there an owner already? */
589 if (vhost_dev_has_owner(dev)) {
590 err = -EBUSY;
591 goto err_mm;
592 }
593
594 vhost_attach_mm(dev);
595
596 dev->kcov_handle = kcov_common_handle();
597 if (dev->use_worker) {
598 worker = kthread_create(vhost_worker, dev,
599 "vhost-%d", current->pid);
600 if (IS_ERR(worker)) {
601 err = PTR_ERR(worker);
602 goto err_worker;
603 }
604
605 dev->worker = worker;
606 wake_up_process(worker); /* avoid contributing to loadavg */
607
608 err = vhost_attach_cgroups(dev);
609 if (err)
610 goto err_cgroup;
611 }
612
613 err = vhost_dev_alloc_iovecs(dev);
614 if (err)
615 goto err_cgroup;
616
617 return 0;
618err_cgroup:
619 if (dev->worker) {
620 kthread_stop(dev->worker);
621 dev->worker = NULL;
622 }
623err_worker:
624 vhost_detach_mm(dev);
625 dev->kcov_handle = 0;
626err_mm:
627 return err;
628}
629EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
630
631static struct vhost_iotlb *iotlb_alloc(void)
632{
633 return vhost_iotlb_alloc(max_iotlb_entries,
634 VHOST_IOTLB_FLAG_RETIRE);
635}
636
637struct vhost_iotlb *vhost_dev_reset_owner_prepare(void)
638{
639 return iotlb_alloc();
640}
641EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
642
643/* Caller should have device mutex */
644void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)
645{
646 int i;
647
648 vhost_dev_cleanup(dev);
649
650 dev->umem = umem;
651 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
652 * VQs aren't running.
653 */
654 for (i = 0; i < dev->nvqs; ++i)
655 dev->vqs[i]->umem = umem;
656}
657EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
658
659void vhost_dev_stop(struct vhost_dev *dev)
660{
661 int i;
662
663 for (i = 0; i < dev->nvqs; ++i) {
664 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
665 vhost_poll_stop(&dev->vqs[i]->poll);
666 vhost_poll_flush(&dev->vqs[i]->poll);
667 }
668 }
669}
670EXPORT_SYMBOL_GPL(vhost_dev_stop);
671
672static void vhost_clear_msg(struct vhost_dev *dev)
673{
674 struct vhost_msg_node *node, *n;
675
676 spin_lock(&dev->iotlb_lock);
677
678 list_for_each_entry_safe(node, n, &dev->read_list, node) {
679 list_del(&node->node);
680 kfree(node);
681 }
682
683 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
684 list_del(&node->node);
685 kfree(node);
686 }
687
688 spin_unlock(&dev->iotlb_lock);
689}
690
691void vhost_dev_cleanup(struct vhost_dev *dev)
692{
693 int i;
694
695 for (i = 0; i < dev->nvqs; ++i) {
696 if (dev->vqs[i]->error_ctx)
697 eventfd_ctx_put(dev->vqs[i]->error_ctx);
698 if (dev->vqs[i]->kick)
699 fput(dev->vqs[i]->kick);
700 if (dev->vqs[i]->call_ctx.ctx)
701 eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
702 vhost_vq_reset(dev, dev->vqs[i]);
703 }
704 vhost_dev_free_iovecs(dev);
705 if (dev->log_ctx)
706 eventfd_ctx_put(dev->log_ctx);
707 dev->log_ctx = NULL;
708 /* No one will access memory at this point */
709 vhost_iotlb_free(dev->umem);
710 dev->umem = NULL;
711 vhost_iotlb_free(dev->iotlb);
712 dev->iotlb = NULL;
713 vhost_clear_msg(dev);
714 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
715 WARN_ON(!llist_empty(&dev->work_list));
716 if (dev->worker) {
717 kthread_stop(dev->worker);
718 dev->worker = NULL;
719 dev->kcov_handle = 0;
720 }
721 vhost_detach_mm(dev);
722}
723EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
724
725static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
726{
727 u64 a = addr / VHOST_PAGE_SIZE / 8;
728
729 /* Make sure 64 bit math will not overflow. */
730 if (a > ULONG_MAX - (unsigned long)log_base ||
731 a + (unsigned long)log_base > ULONG_MAX)
732 return false;
733
734 return access_ok(log_base + a,
735 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
736}
737
738/* Make sure 64 bit math will not overflow. */
739static bool vhost_overflow(u64 uaddr, u64 size)
740{
741 if (uaddr > ULONG_MAX || size > ULONG_MAX)
742 return true;
743
744 if (!size)
745 return false;
746
747 return uaddr > ULONG_MAX - size + 1;
748}
749
750/* Caller should have vq mutex and device mutex. */
751static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem,
752 int log_all)
753{
754 struct vhost_iotlb_map *map;
755
756 if (!umem)
757 return false;
758
759 list_for_each_entry(map, &umem->list, link) {
760 unsigned long a = map->addr;
761
762 if (vhost_overflow(map->addr, map->size))
763 return false;
764
765
766 if (!access_ok((void __user *)a, map->size))
767 return false;
768 else if (log_all && !log_access_ok(log_base,
769 map->start,
770 map->size))
771 return false;
772 }
773 return true;
774}
775
776static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
777 u64 addr, unsigned int size,
778 int type)
779{
780 const struct vhost_iotlb_map *map = vq->meta_iotlb[type];
781
782 if (!map)
783 return NULL;
784
785 return (void __user *)(uintptr_t)(map->addr + addr - map->start);
786}
787
788/* Can we switch to this memory table? */
789/* Caller should have device mutex but not vq mutex */
790static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem,
791 int log_all)
792{
793 int i;
794
795 for (i = 0; i < d->nvqs; ++i) {
796 bool ok;
797 bool log;
798
799 mutex_lock(&d->vqs[i]->mutex);
800 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
801 /* If ring is inactive, will check when it's enabled. */
802 if (d->vqs[i]->private_data)
803 ok = vq_memory_access_ok(d->vqs[i]->log_base,
804 umem, log);
805 else
806 ok = true;
807 mutex_unlock(&d->vqs[i]->mutex);
808 if (!ok)
809 return false;
810 }
811 return true;
812}
813
814static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
815 struct iovec iov[], int iov_size, int access);
816
817static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
818 const void *from, unsigned size)
819{
820 int ret;
821
822 if (!vq->iotlb)
823 return __copy_to_user(to, from, size);
824 else {
825 /* This function should be called after iotlb
826 * prefetch, which means we're sure that all vq
827 * could be access through iotlb. So -EAGAIN should
828 * not happen in this case.
829 */
830 struct iov_iter t;
831 void __user *uaddr = vhost_vq_meta_fetch(vq,
832 (u64)(uintptr_t)to, size,
833 VHOST_ADDR_USED);
834
835 if (uaddr)
836 return __copy_to_user(uaddr, from, size);
837
838 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
839 ARRAY_SIZE(vq->iotlb_iov),
840 VHOST_ACCESS_WO);
841 if (ret < 0)
842 goto out;
843 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
844 ret = copy_to_iter(from, size, &t);
845 if (ret == size)
846 ret = 0;
847 }
848out:
849 return ret;
850}
851
852static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
853 void __user *from, unsigned size)
854{
855 int ret;
856
857 if (!vq->iotlb)
858 return __copy_from_user(to, from, size);
859 else {
860 /* This function should be called after iotlb
861 * prefetch, which means we're sure that vq
862 * could be access through iotlb. So -EAGAIN should
863 * not happen in this case.
864 */
865 void __user *uaddr = vhost_vq_meta_fetch(vq,
866 (u64)(uintptr_t)from, size,
867 VHOST_ADDR_DESC);
868 struct iov_iter f;
869
870 if (uaddr)
871 return __copy_from_user(to, uaddr, size);
872
873 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
874 ARRAY_SIZE(vq->iotlb_iov),
875 VHOST_ACCESS_RO);
876 if (ret < 0) {
877 vq_err(vq, "IOTLB translation failure: uaddr "
878 "%p size 0x%llx\n", from,
879 (unsigned long long) size);
880 goto out;
881 }
882 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
883 ret = copy_from_iter(to, size, &f);
884 if (ret == size)
885 ret = 0;
886 }
887
888out:
889 return ret;
890}
891
892static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
893 void __user *addr, unsigned int size,
894 int type)
895{
896 int ret;
897
898 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
899 ARRAY_SIZE(vq->iotlb_iov),
900 VHOST_ACCESS_RO);
901 if (ret < 0) {
902 vq_err(vq, "IOTLB translation failure: uaddr "
903 "%p size 0x%llx\n", addr,
904 (unsigned long long) size);
905 return NULL;
906 }
907
908 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
909 vq_err(vq, "Non atomic userspace memory access: uaddr "
910 "%p size 0x%llx\n", addr,
911 (unsigned long long) size);
912 return NULL;
913 }
914
915 return vq->iotlb_iov[0].iov_base;
916}
917
918/* This function should be called after iotlb
919 * prefetch, which means we're sure that vq
920 * could be access through iotlb. So -EAGAIN should
921 * not happen in this case.
922 */
923static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
924 void __user *addr, unsigned int size,
925 int type)
926{
927 void __user *uaddr = vhost_vq_meta_fetch(vq,
928 (u64)(uintptr_t)addr, size, type);
929 if (uaddr)
930 return uaddr;
931
932 return __vhost_get_user_slow(vq, addr, size, type);
933}
934
935#define vhost_put_user(vq, x, ptr) \
936({ \
937 int ret; \
938 if (!vq->iotlb) { \
939 ret = __put_user(x, ptr); \
940 } else { \
941 __typeof__(ptr) to = \
942 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
943 sizeof(*ptr), VHOST_ADDR_USED); \
944 if (to != NULL) \
945 ret = __put_user(x, to); \
946 else \
947 ret = -EFAULT; \
948 } \
949 ret; \
950})
951
952static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
953{
954 return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
955 vhost_avail_event(vq));
956}
957
958static inline int vhost_put_used(struct vhost_virtqueue *vq,
959 struct vring_used_elem *head, int idx,
960 int count)
961{
962 return vhost_copy_to_user(vq, vq->used->ring + idx, head,
963 count * sizeof(*head));
964}
965
966static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
967
968{
969 return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
970 &vq->used->flags);
971}
972
973static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
974
975{
976 return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
977 &vq->used->idx);
978}
979
980#define vhost_get_user(vq, x, ptr, type) \
981({ \
982 int ret; \
983 if (!vq->iotlb) { \
984 ret = __get_user(x, ptr); \
985 } else { \
986 __typeof__(ptr) from = \
987 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
988 sizeof(*ptr), \
989 type); \
990 if (from != NULL) \
991 ret = __get_user(x, from); \
992 else \
993 ret = -EFAULT; \
994 } \
995 ret; \
996})
997
998#define vhost_get_avail(vq, x, ptr) \
999 vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
1000
1001#define vhost_get_used(vq, x, ptr) \
1002 vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
1003
1004static void vhost_dev_lock_vqs(struct vhost_dev *d)
1005{
1006 int i = 0;
1007 for (i = 0; i < d->nvqs; ++i)
1008 mutex_lock_nested(&d->vqs[i]->mutex, i);
1009}
1010
1011static void vhost_dev_unlock_vqs(struct vhost_dev *d)
1012{
1013 int i = 0;
1014 for (i = 0; i < d->nvqs; ++i)
1015 mutex_unlock(&d->vqs[i]->mutex);
1016}
1017
1018static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
1019 __virtio16 *idx)
1020{
1021 return vhost_get_avail(vq, *idx, &vq->avail->idx);
1022}
1023
1024static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
1025 __virtio16 *head, int idx)
1026{
1027 return vhost_get_avail(vq, *head,
1028 &vq->avail->ring[idx & (vq->num - 1)]);
1029}
1030
1031static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
1032 __virtio16 *flags)
1033{
1034 return vhost_get_avail(vq, *flags, &vq->avail->flags);
1035}
1036
1037static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
1038 __virtio16 *event)
1039{
1040 return vhost_get_avail(vq, *event, vhost_used_event(vq));
1041}
1042
1043static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
1044 __virtio16 *idx)
1045{
1046 return vhost_get_used(vq, *idx, &vq->used->idx);
1047}
1048
1049static inline int vhost_get_desc(struct vhost_virtqueue *vq,
1050 struct vring_desc *desc, int idx)
1051{
1052 return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
1053}
1054
1055static void vhost_iotlb_notify_vq(struct vhost_dev *d,
1056 struct vhost_iotlb_msg *msg)
1057{
1058 struct vhost_msg_node *node, *n;
1059
1060 spin_lock(&d->iotlb_lock);
1061
1062 list_for_each_entry_safe(node, n, &d->pending_list, node) {
1063 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
1064 if (msg->iova <= vq_msg->iova &&
1065 msg->iova + msg->size - 1 >= vq_msg->iova &&
1066 vq_msg->type == VHOST_IOTLB_MISS) {
1067 vhost_poll_queue(&node->vq->poll);
1068 list_del(&node->node);
1069 kfree(node);
1070 }
1071 }
1072
1073 spin_unlock(&d->iotlb_lock);
1074}
1075
1076static bool umem_access_ok(u64 uaddr, u64 size, int access)
1077{
1078 unsigned long a = uaddr;
1079
1080 /* Make sure 64 bit math will not overflow. */
1081 if (vhost_overflow(uaddr, size))
1082 return false;
1083
1084 if ((access & VHOST_ACCESS_RO) &&
1085 !access_ok((void __user *)a, size))
1086 return false;
1087 if ((access & VHOST_ACCESS_WO) &&
1088 !access_ok((void __user *)a, size))
1089 return false;
1090 return true;
1091}
1092
1093static int vhost_process_iotlb_msg(struct vhost_dev *dev,
1094 struct vhost_iotlb_msg *msg)
1095{
1096 int ret = 0;
1097
1098 mutex_lock(&dev->mutex);
1099 vhost_dev_lock_vqs(dev);
1100 switch (msg->type) {
1101 case VHOST_IOTLB_UPDATE:
1102 if (!dev->iotlb) {
1103 ret = -EFAULT;
1104 break;
1105 }
1106 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1107 ret = -EFAULT;
1108 break;
1109 }
1110 vhost_vq_meta_reset(dev);
1111 if (vhost_iotlb_add_range(dev->iotlb, msg->iova,
1112 msg->iova + msg->size - 1,
1113 msg->uaddr, msg->perm)) {
1114 ret = -ENOMEM;
1115 break;
1116 }
1117 vhost_iotlb_notify_vq(dev, msg);
1118 break;
1119 case VHOST_IOTLB_INVALIDATE:
1120 if (!dev->iotlb) {
1121 ret = -EFAULT;
1122 break;
1123 }
1124 vhost_vq_meta_reset(dev);
1125 vhost_iotlb_del_range(dev->iotlb, msg->iova,
1126 msg->iova + msg->size - 1);
1127 break;
1128 default:
1129 ret = -EINVAL;
1130 break;
1131 }
1132
1133 vhost_dev_unlock_vqs(dev);
1134 mutex_unlock(&dev->mutex);
1135
1136 return ret;
1137}
1138ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1139 struct iov_iter *from)
1140{
1141 struct vhost_iotlb_msg msg;
1142 size_t offset;
1143 int type, ret;
1144
1145 ret = copy_from_iter(&type, sizeof(type), from);
1146 if (ret != sizeof(type)) {
1147 ret = -EINVAL;
1148 goto done;
1149 }
1150
1151 switch (type) {
1152 case VHOST_IOTLB_MSG:
1153 /* There maybe a hole after type for V1 message type,
1154 * so skip it here.
1155 */
1156 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1157 break;
1158 case VHOST_IOTLB_MSG_V2:
1159 offset = sizeof(__u32);
1160 break;
1161 default:
1162 ret = -EINVAL;
1163 goto done;
1164 }
1165
1166 iov_iter_advance(from, offset);
1167 ret = copy_from_iter(&msg, sizeof(msg), from);
1168 if (ret != sizeof(msg)) {
1169 ret = -EINVAL;
1170 goto done;
1171 }
1172
1173 if (dev->msg_handler)
1174 ret = dev->msg_handler(dev, &msg);
1175 else
1176 ret = vhost_process_iotlb_msg(dev, &msg);
1177 if (ret) {
1178 ret = -EFAULT;
1179 goto done;
1180 }
1181
1182 ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1183 sizeof(struct vhost_msg_v2);
1184done:
1185 return ret;
1186}
1187EXPORT_SYMBOL(vhost_chr_write_iter);
1188
1189__poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1190 poll_table *wait)
1191{
1192 __poll_t mask = 0;
1193
1194 poll_wait(file, &dev->wait, wait);
1195
1196 if (!list_empty(&dev->read_list))
1197 mask |= EPOLLIN | EPOLLRDNORM;
1198
1199 return mask;
1200}
1201EXPORT_SYMBOL(vhost_chr_poll);
1202
1203ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1204 int noblock)
1205{
1206 DEFINE_WAIT(wait);
1207 struct vhost_msg_node *node;
1208 ssize_t ret = 0;
1209 unsigned size = sizeof(struct vhost_msg);
1210
1211 if (iov_iter_count(to) < size)
1212 return 0;
1213
1214 while (1) {
1215 if (!noblock)
1216 prepare_to_wait(&dev->wait, &wait,
1217 TASK_INTERRUPTIBLE);
1218
1219 node = vhost_dequeue_msg(dev, &dev->read_list);
1220 if (node)
1221 break;
1222 if (noblock) {
1223 ret = -EAGAIN;
1224 break;
1225 }
1226 if (signal_pending(current)) {
1227 ret = -ERESTARTSYS;
1228 break;
1229 }
1230 if (!dev->iotlb) {
1231 ret = -EBADFD;
1232 break;
1233 }
1234
1235 schedule();
1236 }
1237
1238 if (!noblock)
1239 finish_wait(&dev->wait, &wait);
1240
1241 if (node) {
1242 struct vhost_iotlb_msg *msg;
1243 void *start = &node->msg;
1244
1245 switch (node->msg.type) {
1246 case VHOST_IOTLB_MSG:
1247 size = sizeof(node->msg);
1248 msg = &node->msg.iotlb;
1249 break;
1250 case VHOST_IOTLB_MSG_V2:
1251 size = sizeof(node->msg_v2);
1252 msg = &node->msg_v2.iotlb;
1253 break;
1254 default:
1255 BUG();
1256 break;
1257 }
1258
1259 ret = copy_to_iter(start, size, to);
1260 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1261 kfree(node);
1262 return ret;
1263 }
1264 vhost_enqueue_msg(dev, &dev->pending_list, node);
1265 }
1266
1267 return ret;
1268}
1269EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1270
1271static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1272{
1273 struct vhost_dev *dev = vq->dev;
1274 struct vhost_msg_node *node;
1275 struct vhost_iotlb_msg *msg;
1276 bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1277
1278 node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1279 if (!node)
1280 return -ENOMEM;
1281
1282 if (v2) {
1283 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1284 msg = &node->msg_v2.iotlb;
1285 } else {
1286 msg = &node->msg.iotlb;
1287 }
1288
1289 msg->type = VHOST_IOTLB_MISS;
1290 msg->iova = iova;
1291 msg->perm = access;
1292
1293 vhost_enqueue_msg(dev, &dev->read_list, node);
1294
1295 return 0;
1296}
1297
1298static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1299 vring_desc_t __user *desc,
1300 vring_avail_t __user *avail,
1301 vring_used_t __user *used)
1302
1303{
1304 /* If an IOTLB device is present, the vring addresses are
1305 * GIOVAs. Access validation occurs at prefetch time. */
1306 if (vq->iotlb)
1307 return true;
1308
1309 return access_ok(desc, vhost_get_desc_size(vq, num)) &&
1310 access_ok(avail, vhost_get_avail_size(vq, num)) &&
1311 access_ok(used, vhost_get_used_size(vq, num));
1312}
1313
1314static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1315 const struct vhost_iotlb_map *map,
1316 int type)
1317{
1318 int access = (type == VHOST_ADDR_USED) ?
1319 VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1320
1321 if (likely(map->perm & access))
1322 vq->meta_iotlb[type] = map;
1323}
1324
1325static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1326 int access, u64 addr, u64 len, int type)
1327{
1328 const struct vhost_iotlb_map *map;
1329 struct vhost_iotlb *umem = vq->iotlb;
1330 u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1331
1332 if (vhost_vq_meta_fetch(vq, addr, len, type))
1333 return true;
1334
1335 while (len > s) {
1336 map = vhost_iotlb_itree_first(umem, addr, last);
1337 if (map == NULL || map->start > addr) {
1338 vhost_iotlb_miss(vq, addr, access);
1339 return false;
1340 } else if (!(map->perm & access)) {
1341 /* Report the possible access violation by
1342 * request another translation from userspace.
1343 */
1344 return false;
1345 }
1346
1347 size = map->size - addr + map->start;
1348
1349 if (orig_addr == addr && size >= len)
1350 vhost_vq_meta_update(vq, map, type);
1351
1352 s += size;
1353 addr += size;
1354 }
1355
1356 return true;
1357}
1358
1359int vq_meta_prefetch(struct vhost_virtqueue *vq)
1360{
1361 unsigned int num = vq->num;
1362
1363 if (!vq->iotlb)
1364 return 1;
1365
1366 return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc,
1367 vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
1368 iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail,
1369 vhost_get_avail_size(vq, num),
1370 VHOST_ADDR_AVAIL) &&
1371 iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used,
1372 vhost_get_used_size(vq, num), VHOST_ADDR_USED);
1373}
1374EXPORT_SYMBOL_GPL(vq_meta_prefetch);
1375
1376/* Can we log writes? */
1377/* Caller should have device mutex but not vq mutex */
1378bool vhost_log_access_ok(struct vhost_dev *dev)
1379{
1380 return memory_access_ok(dev, dev->umem, 1);
1381}
1382EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1383
1384static bool vq_log_used_access_ok(struct vhost_virtqueue *vq,
1385 void __user *log_base,
1386 bool log_used,
1387 u64 log_addr)
1388{
1389 /* If an IOTLB device is present, log_addr is a GIOVA that
1390 * will never be logged by log_used(). */
1391 if (vq->iotlb)
1392 return true;
1393
1394 return !log_used || log_access_ok(log_base, log_addr,
1395 vhost_get_used_size(vq, vq->num));
1396}
1397
1398/* Verify access for write logging. */
1399/* Caller should have vq mutex and device mutex */
1400static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1401 void __user *log_base)
1402{
1403 return vq_memory_access_ok(log_base, vq->umem,
1404 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1405 vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr);
1406}
1407
1408/* Can we start vq? */
1409/* Caller should have vq mutex and device mutex */
1410bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1411{
1412 if (!vq_log_access_ok(vq, vq->log_base))
1413 return false;
1414
1415 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1416}
1417EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1418
1419static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1420{
1421 struct vhost_memory mem, *newmem;
1422 struct vhost_memory_region *region;
1423 struct vhost_iotlb *newumem, *oldumem;
1424 unsigned long size = offsetof(struct vhost_memory, regions);
1425 int i;
1426
1427 if (copy_from_user(&mem, m, size))
1428 return -EFAULT;
1429 if (mem.padding)
1430 return -EOPNOTSUPP;
1431 if (mem.nregions > max_mem_regions)
1432 return -E2BIG;
1433 newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1434 GFP_KERNEL);
1435 if (!newmem)
1436 return -ENOMEM;
1437
1438 memcpy(newmem, &mem, size);
1439 if (copy_from_user(newmem->regions, m->regions,
1440 flex_array_size(newmem, regions, mem.nregions))) {
1441 kvfree(newmem);
1442 return -EFAULT;
1443 }
1444
1445 newumem = iotlb_alloc();
1446 if (!newumem) {
1447 kvfree(newmem);
1448 return -ENOMEM;
1449 }
1450
1451 for (region = newmem->regions;
1452 region < newmem->regions + mem.nregions;
1453 region++) {
1454 if (vhost_iotlb_add_range(newumem,
1455 region->guest_phys_addr,
1456 region->guest_phys_addr +
1457 region->memory_size - 1,
1458 region->userspace_addr,
1459 VHOST_MAP_RW))
1460 goto err;
1461 }
1462
1463 if (!memory_access_ok(d, newumem, 0))
1464 goto err;
1465
1466 oldumem = d->umem;
1467 d->umem = newumem;
1468
1469 /* All memory accesses are done under some VQ mutex. */
1470 for (i = 0; i < d->nvqs; ++i) {
1471 mutex_lock(&d->vqs[i]->mutex);
1472 d->vqs[i]->umem = newumem;
1473 mutex_unlock(&d->vqs[i]->mutex);
1474 }
1475
1476 kvfree(newmem);
1477 vhost_iotlb_free(oldumem);
1478 return 0;
1479
1480err:
1481 vhost_iotlb_free(newumem);
1482 kvfree(newmem);
1483 return -EFAULT;
1484}
1485
1486static long vhost_vring_set_num(struct vhost_dev *d,
1487 struct vhost_virtqueue *vq,
1488 void __user *argp)
1489{
1490 struct vhost_vring_state s;
1491
1492 /* Resizing ring with an active backend?
1493 * You don't want to do that. */
1494 if (vq->private_data)
1495 return -EBUSY;
1496
1497 if (copy_from_user(&s, argp, sizeof s))
1498 return -EFAULT;
1499
1500 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
1501 return -EINVAL;
1502 vq->num = s.num;
1503
1504 return 0;
1505}
1506
1507static long vhost_vring_set_addr(struct vhost_dev *d,
1508 struct vhost_virtqueue *vq,
1509 void __user *argp)
1510{
1511 struct vhost_vring_addr a;
1512
1513 if (copy_from_user(&a, argp, sizeof a))
1514 return -EFAULT;
1515 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
1516 return -EOPNOTSUPP;
1517
1518 /* For 32bit, verify that the top 32bits of the user
1519 data are set to zero. */
1520 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1521 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1522 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
1523 return -EFAULT;
1524
1525 /* Make sure it's safe to cast pointers to vring types. */
1526 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1527 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1528 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1529 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1530 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
1531 return -EINVAL;
1532
1533 /* We only verify access here if backend is configured.
1534 * If it is not, we don't as size might not have been setup.
1535 * We will verify when backend is configured. */
1536 if (vq->private_data) {
1537 if (!vq_access_ok(vq, vq->num,
1538 (void __user *)(unsigned long)a.desc_user_addr,
1539 (void __user *)(unsigned long)a.avail_user_addr,
1540 (void __user *)(unsigned long)a.used_user_addr))
1541 return -EINVAL;
1542
1543 /* Also validate log access for used ring if enabled. */
1544 if (!vq_log_used_access_ok(vq, vq->log_base,
1545 a.flags & (0x1 << VHOST_VRING_F_LOG),
1546 a.log_guest_addr))
1547 return -EINVAL;
1548 }
1549
1550 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1551 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1552 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1553 vq->log_addr = a.log_guest_addr;
1554 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1555
1556 return 0;
1557}
1558
1559static long vhost_vring_set_num_addr(struct vhost_dev *d,
1560 struct vhost_virtqueue *vq,
1561 unsigned int ioctl,
1562 void __user *argp)
1563{
1564 long r;
1565
1566 mutex_lock(&vq->mutex);
1567
1568 switch (ioctl) {
1569 case VHOST_SET_VRING_NUM:
1570 r = vhost_vring_set_num(d, vq, argp);
1571 break;
1572 case VHOST_SET_VRING_ADDR:
1573 r = vhost_vring_set_addr(d, vq, argp);
1574 break;
1575 default:
1576 BUG();
1577 }
1578
1579 mutex_unlock(&vq->mutex);
1580
1581 return r;
1582}
1583long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1584{
1585 struct file *eventfp, *filep = NULL;
1586 bool pollstart = false, pollstop = false;
1587 struct eventfd_ctx *ctx = NULL;
1588 u32 __user *idxp = argp;
1589 struct vhost_virtqueue *vq;
1590 struct vhost_vring_state s;
1591 struct vhost_vring_file f;
1592 u32 idx;
1593 long r;
1594
1595 r = get_user(idx, idxp);
1596 if (r < 0)
1597 return r;
1598 if (idx >= d->nvqs)
1599 return -ENOBUFS;
1600
1601 idx = array_index_nospec(idx, d->nvqs);
1602 vq = d->vqs[idx];
1603
1604 if (ioctl == VHOST_SET_VRING_NUM ||
1605 ioctl == VHOST_SET_VRING_ADDR) {
1606 return vhost_vring_set_num_addr(d, vq, ioctl, argp);
1607 }
1608
1609 mutex_lock(&vq->mutex);
1610
1611 switch (ioctl) {
1612 case VHOST_SET_VRING_BASE:
1613 /* Moving base with an active backend?
1614 * You don't want to do that. */
1615 if (vq->private_data) {
1616 r = -EBUSY;
1617 break;
1618 }
1619 if (copy_from_user(&s, argp, sizeof s)) {
1620 r = -EFAULT;
1621 break;
1622 }
1623 if (s.num > 0xffff) {
1624 r = -EINVAL;
1625 break;
1626 }
1627 vq->last_avail_idx = s.num;
1628 /* Forget the cached index value. */
1629 vq->avail_idx = vq->last_avail_idx;
1630 break;
1631 case VHOST_GET_VRING_BASE:
1632 s.index = idx;
1633 s.num = vq->last_avail_idx;
1634 if (copy_to_user(argp, &s, sizeof s))
1635 r = -EFAULT;
1636 break;
1637 case VHOST_SET_VRING_KICK:
1638 if (copy_from_user(&f, argp, sizeof f)) {
1639 r = -EFAULT;
1640 break;
1641 }
1642 eventfp = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_fget(f.fd);
1643 if (IS_ERR(eventfp)) {
1644 r = PTR_ERR(eventfp);
1645 break;
1646 }
1647 if (eventfp != vq->kick) {
1648 pollstop = (filep = vq->kick) != NULL;
1649 pollstart = (vq->kick = eventfp) != NULL;
1650 } else
1651 filep = eventfp;
1652 break;
1653 case VHOST_SET_VRING_CALL:
1654 if (copy_from_user(&f, argp, sizeof f)) {
1655 r = -EFAULT;
1656 break;
1657 }
1658 ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
1659 if (IS_ERR(ctx)) {
1660 r = PTR_ERR(ctx);
1661 break;
1662 }
1663
1664 swap(ctx, vq->call_ctx.ctx);
1665 break;
1666 case VHOST_SET_VRING_ERR:
1667 if (copy_from_user(&f, argp, sizeof f)) {
1668 r = -EFAULT;
1669 break;
1670 }
1671 ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
1672 if (IS_ERR(ctx)) {
1673 r = PTR_ERR(ctx);
1674 break;
1675 }
1676 swap(ctx, vq->error_ctx);
1677 break;
1678 case VHOST_SET_VRING_ENDIAN:
1679 r = vhost_set_vring_endian(vq, argp);
1680 break;
1681 case VHOST_GET_VRING_ENDIAN:
1682 r = vhost_get_vring_endian(vq, idx, argp);
1683 break;
1684 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1685 if (copy_from_user(&s, argp, sizeof(s))) {
1686 r = -EFAULT;
1687 break;
1688 }
1689 vq->busyloop_timeout = s.num;
1690 break;
1691 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1692 s.index = idx;
1693 s.num = vq->busyloop_timeout;
1694 if (copy_to_user(argp, &s, sizeof(s)))
1695 r = -EFAULT;
1696 break;
1697 default:
1698 r = -ENOIOCTLCMD;
1699 }
1700
1701 if (pollstop && vq->handle_kick)
1702 vhost_poll_stop(&vq->poll);
1703
1704 if (!IS_ERR_OR_NULL(ctx))
1705 eventfd_ctx_put(ctx);
1706 if (filep)
1707 fput(filep);
1708
1709 if (pollstart && vq->handle_kick)
1710 r = vhost_poll_start(&vq->poll, vq->kick);
1711
1712 mutex_unlock(&vq->mutex);
1713
1714 if (pollstop && vq->handle_kick)
1715 vhost_poll_flush(&vq->poll);
1716 return r;
1717}
1718EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1719
1720int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1721{
1722 struct vhost_iotlb *niotlb, *oiotlb;
1723 int i;
1724
1725 niotlb = iotlb_alloc();
1726 if (!niotlb)
1727 return -ENOMEM;
1728
1729 oiotlb = d->iotlb;
1730 d->iotlb = niotlb;
1731
1732 for (i = 0; i < d->nvqs; ++i) {
1733 struct vhost_virtqueue *vq = d->vqs[i];
1734
1735 mutex_lock(&vq->mutex);
1736 vq->iotlb = niotlb;
1737 __vhost_vq_meta_reset(vq);
1738 mutex_unlock(&vq->mutex);
1739 }
1740
1741 vhost_iotlb_free(oiotlb);
1742
1743 return 0;
1744}
1745EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1746
1747/* Caller must have device mutex */
1748long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1749{
1750 struct eventfd_ctx *ctx;
1751 u64 p;
1752 long r;
1753 int i, fd;
1754
1755 /* If you are not the owner, you can become one */
1756 if (ioctl == VHOST_SET_OWNER) {
1757 r = vhost_dev_set_owner(d);
1758 goto done;
1759 }
1760
1761 /* You must be the owner to do anything else */
1762 r = vhost_dev_check_owner(d);
1763 if (r)
1764 goto done;
1765
1766 switch (ioctl) {
1767 case VHOST_SET_MEM_TABLE:
1768 r = vhost_set_memory(d, argp);
1769 break;
1770 case VHOST_SET_LOG_BASE:
1771 if (copy_from_user(&p, argp, sizeof p)) {
1772 r = -EFAULT;
1773 break;
1774 }
1775 if ((u64)(unsigned long)p != p) {
1776 r = -EFAULT;
1777 break;
1778 }
1779 for (i = 0; i < d->nvqs; ++i) {
1780 struct vhost_virtqueue *vq;
1781 void __user *base = (void __user *)(unsigned long)p;
1782 vq = d->vqs[i];
1783 mutex_lock(&vq->mutex);
1784 /* If ring is inactive, will check when it's enabled. */
1785 if (vq->private_data && !vq_log_access_ok(vq, base))
1786 r = -EFAULT;
1787 else
1788 vq->log_base = base;
1789 mutex_unlock(&vq->mutex);
1790 }
1791 break;
1792 case VHOST_SET_LOG_FD:
1793 r = get_user(fd, (int __user *)argp);
1794 if (r < 0)
1795 break;
1796 ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd);
1797 if (IS_ERR(ctx)) {
1798 r = PTR_ERR(ctx);
1799 break;
1800 }
1801 swap(ctx, d->log_ctx);
1802 for (i = 0; i < d->nvqs; ++i) {
1803 mutex_lock(&d->vqs[i]->mutex);
1804 d->vqs[i]->log_ctx = d->log_ctx;
1805 mutex_unlock(&d->vqs[i]->mutex);
1806 }
1807 if (ctx)
1808 eventfd_ctx_put(ctx);
1809 break;
1810 default:
1811 r = -ENOIOCTLCMD;
1812 break;
1813 }
1814done:
1815 return r;
1816}
1817EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1818
1819/* TODO: This is really inefficient. We need something like get_user()
1820 * (instruction directly accesses the data, with an exception table entry
1821 * returning -EFAULT). See Documentation/x86/exception-tables.rst.
1822 */
1823static int set_bit_to_user(int nr, void __user *addr)
1824{
1825 unsigned long log = (unsigned long)addr;
1826 struct page *page;
1827 void *base;
1828 int bit = nr + (log % PAGE_SIZE) * 8;
1829 int r;
1830
1831 r = pin_user_pages_fast(log, 1, FOLL_WRITE, &page);
1832 if (r < 0)
1833 return r;
1834 BUG_ON(r != 1);
1835 base = kmap_atomic(page);
1836 set_bit(bit, base);
1837 kunmap_atomic(base);
1838 unpin_user_pages_dirty_lock(&page, 1, true);
1839 return 0;
1840}
1841
1842static int log_write(void __user *log_base,
1843 u64 write_address, u64 write_length)
1844{
1845 u64 write_page = write_address / VHOST_PAGE_SIZE;
1846 int r;
1847
1848 if (!write_length)
1849 return 0;
1850 write_length += write_address % VHOST_PAGE_SIZE;
1851 for (;;) {
1852 u64 base = (u64)(unsigned long)log_base;
1853 u64 log = base + write_page / 8;
1854 int bit = write_page % 8;
1855 if ((u64)(unsigned long)log != log)
1856 return -EFAULT;
1857 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1858 if (r < 0)
1859 return r;
1860 if (write_length <= VHOST_PAGE_SIZE)
1861 break;
1862 write_length -= VHOST_PAGE_SIZE;
1863 write_page += 1;
1864 }
1865 return r;
1866}
1867
1868static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
1869{
1870 struct vhost_iotlb *umem = vq->umem;
1871 struct vhost_iotlb_map *u;
1872 u64 start, end, l, min;
1873 int r;
1874 bool hit = false;
1875
1876 while (len) {
1877 min = len;
1878 /* More than one GPAs can be mapped into a single HVA. So
1879 * iterate all possible umems here to be safe.
1880 */
1881 list_for_each_entry(u, &umem->list, link) {
1882 if (u->addr > hva - 1 + len ||
1883 u->addr - 1 + u->size < hva)
1884 continue;
1885 start = max(u->addr, hva);
1886 end = min(u->addr - 1 + u->size, hva - 1 + len);
1887 l = end - start + 1;
1888 r = log_write(vq->log_base,
1889 u->start + start - u->addr,
1890 l);
1891 if (r < 0)
1892 return r;
1893 hit = true;
1894 min = min(l, min);
1895 }
1896
1897 if (!hit)
1898 return -EFAULT;
1899
1900 len -= min;
1901 hva += min;
1902 }
1903
1904 return 0;
1905}
1906
1907static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
1908{
1909 struct iovec *iov = vq->log_iov;
1910 int i, ret;
1911
1912 if (!vq->iotlb)
1913 return log_write(vq->log_base, vq->log_addr + used_offset, len);
1914
1915 ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
1916 len, iov, 64, VHOST_ACCESS_WO);
1917 if (ret < 0)
1918 return ret;
1919
1920 for (i = 0; i < ret; i++) {
1921 ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1922 iov[i].iov_len);
1923 if (ret)
1924 return ret;
1925 }
1926
1927 return 0;
1928}
1929
1930int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1931 unsigned int log_num, u64 len, struct iovec *iov, int count)
1932{
1933 int i, r;
1934
1935 /* Make sure data written is seen before log. */
1936 smp_wmb();
1937
1938 if (vq->iotlb) {
1939 for (i = 0; i < count; i++) {
1940 r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1941 iov[i].iov_len);
1942 if (r < 0)
1943 return r;
1944 }
1945 return 0;
1946 }
1947
1948 for (i = 0; i < log_num; ++i) {
1949 u64 l = min(log[i].len, len);
1950 r = log_write(vq->log_base, log[i].addr, l);
1951 if (r < 0)
1952 return r;
1953 len -= l;
1954 if (!len) {
1955 if (vq->log_ctx)
1956 eventfd_signal(vq->log_ctx, 1);
1957 return 0;
1958 }
1959 }
1960 /* Length written exceeds what we have stored. This is a bug. */
1961 BUG();
1962 return 0;
1963}
1964EXPORT_SYMBOL_GPL(vhost_log_write);
1965
1966static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1967{
1968 void __user *used;
1969 if (vhost_put_used_flags(vq))
1970 return -EFAULT;
1971 if (unlikely(vq->log_used)) {
1972 /* Make sure the flag is seen before log. */
1973 smp_wmb();
1974 /* Log used flag write. */
1975 used = &vq->used->flags;
1976 log_used(vq, (used - (void __user *)vq->used),
1977 sizeof vq->used->flags);
1978 if (vq->log_ctx)
1979 eventfd_signal(vq->log_ctx, 1);
1980 }
1981 return 0;
1982}
1983
1984static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1985{
1986 if (vhost_put_avail_event(vq))
1987 return -EFAULT;
1988 if (unlikely(vq->log_used)) {
1989 void __user *used;
1990 /* Make sure the event is seen before log. */
1991 smp_wmb();
1992 /* Log avail event write */
1993 used = vhost_avail_event(vq);
1994 log_used(vq, (used - (void __user *)vq->used),
1995 sizeof *vhost_avail_event(vq));
1996 if (vq->log_ctx)
1997 eventfd_signal(vq->log_ctx, 1);
1998 }
1999 return 0;
2000}
2001
2002int vhost_vq_init_access(struct vhost_virtqueue *vq)
2003{
2004 __virtio16 last_used_idx;
2005 int r;
2006 bool is_le = vq->is_le;
2007
2008 if (!vq->private_data)
2009 return 0;
2010
2011 vhost_init_is_le(vq);
2012
2013 r = vhost_update_used_flags(vq);
2014 if (r)
2015 goto err;
2016 vq->signalled_used_valid = false;
2017 if (!vq->iotlb &&
2018 !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
2019 r = -EFAULT;
2020 goto err;
2021 }
2022 r = vhost_get_used_idx(vq, &last_used_idx);
2023 if (r) {
2024 vq_err(vq, "Can't access used idx at %p\n",
2025 &vq->used->idx);
2026 goto err;
2027 }
2028 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
2029 return 0;
2030
2031err:
2032 vq->is_le = is_le;
2033 return r;
2034}
2035EXPORT_SYMBOL_GPL(vhost_vq_init_access);
2036
2037static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
2038 struct iovec iov[], int iov_size, int access)
2039{
2040 const struct vhost_iotlb_map *map;
2041 struct vhost_dev *dev = vq->dev;
2042 struct vhost_iotlb *umem = dev->iotlb ? dev->iotlb : dev->umem;
2043 struct iovec *_iov;
2044 u64 s = 0;
2045 int ret = 0;
2046
2047 while ((u64)len > s) {
2048 u64 size;
2049 if (unlikely(ret >= iov_size)) {
2050 ret = -ENOBUFS;
2051 break;
2052 }
2053
2054 map = vhost_iotlb_itree_first(umem, addr, addr + len - 1);
2055 if (map == NULL || map->start > addr) {
2056 if (umem != dev->iotlb) {
2057 ret = -EFAULT;
2058 break;
2059 }
2060 ret = -EAGAIN;
2061 break;
2062 } else if (!(map->perm & access)) {
2063 ret = -EPERM;
2064 break;
2065 }
2066
2067 _iov = iov + ret;
2068 size = map->size - addr + map->start;
2069 _iov->iov_len = min((u64)len - s, size);
2070 _iov->iov_base = (void __user *)(unsigned long)
2071 (map->addr + addr - map->start);
2072 s += size;
2073 addr += size;
2074 ++ret;
2075 }
2076
2077 if (ret == -EAGAIN)
2078 vhost_iotlb_miss(vq, addr, access);
2079 return ret;
2080}
2081
2082/* Each buffer in the virtqueues is actually a chain of descriptors. This
2083 * function returns the next descriptor in the chain,
2084 * or -1U if we're at the end. */
2085static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
2086{
2087 unsigned int next;
2088
2089 /* If this descriptor says it doesn't chain, we're done. */
2090 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
2091 return -1U;
2092
2093 /* Check they're not leading us off end of descriptors. */
2094 next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
2095 return next;
2096}
2097
2098static int get_indirect(struct vhost_virtqueue *vq,
2099 struct iovec iov[], unsigned int iov_size,
2100 unsigned int *out_num, unsigned int *in_num,
2101 struct vhost_log *log, unsigned int *log_num,
2102 struct vring_desc *indirect)
2103{
2104 struct vring_desc desc;
2105 unsigned int i = 0, count, found = 0;
2106 u32 len = vhost32_to_cpu(vq, indirect->len);
2107 struct iov_iter from;
2108 int ret, access;
2109
2110 /* Sanity check */
2111 if (unlikely(len % sizeof desc)) {
2112 vq_err(vq, "Invalid length in indirect descriptor: "
2113 "len 0x%llx not multiple of 0x%zx\n",
2114 (unsigned long long)len,
2115 sizeof desc);
2116 return -EINVAL;
2117 }
2118
2119 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
2120 UIO_MAXIOV, VHOST_ACCESS_RO);
2121 if (unlikely(ret < 0)) {
2122 if (ret != -EAGAIN)
2123 vq_err(vq, "Translation failure %d in indirect.\n", ret);
2124 return ret;
2125 }
2126 iov_iter_init(&from, READ, vq->indirect, ret, len);
2127 count = len / sizeof desc;
2128 /* Buffers are chained via a 16 bit next field, so
2129 * we can have at most 2^16 of these. */
2130 if (unlikely(count > USHRT_MAX + 1)) {
2131 vq_err(vq, "Indirect buffer length too big: %d\n",
2132 indirect->len);
2133 return -E2BIG;
2134 }
2135
2136 do {
2137 unsigned iov_count = *in_num + *out_num;
2138 if (unlikely(++found > count)) {
2139 vq_err(vq, "Loop detected: last one at %u "
2140 "indirect size %u\n",
2141 i, count);
2142 return -EINVAL;
2143 }
2144 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
2145 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
2146 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2147 return -EINVAL;
2148 }
2149 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
2150 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
2151 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2152 return -EINVAL;
2153 }
2154
2155 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2156 access = VHOST_ACCESS_WO;
2157 else
2158 access = VHOST_ACCESS_RO;
2159
2160 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2161 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2162 iov_size - iov_count, access);
2163 if (unlikely(ret < 0)) {
2164 if (ret != -EAGAIN)
2165 vq_err(vq, "Translation failure %d indirect idx %d\n",
2166 ret, i);
2167 return ret;
2168 }
2169 /* If this is an input descriptor, increment that count. */
2170 if (access == VHOST_ACCESS_WO) {
2171 *in_num += ret;
2172 if (unlikely(log && ret)) {
2173 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2174 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2175 ++*log_num;
2176 }
2177 } else {
2178 /* If it's an output descriptor, they're all supposed
2179 * to come before any input descriptors. */
2180 if (unlikely(*in_num)) {
2181 vq_err(vq, "Indirect descriptor "
2182 "has out after in: idx %d\n", i);
2183 return -EINVAL;
2184 }
2185 *out_num += ret;
2186 }
2187 } while ((i = next_desc(vq, &desc)) != -1);
2188 return 0;
2189}
2190
2191/* This looks in the virtqueue and for the first available buffer, and converts
2192 * it to an iovec for convenient access. Since descriptors consist of some
2193 * number of output then some number of input descriptors, it's actually two
2194 * iovecs, but we pack them into one and note how many of each there were.
2195 *
2196 * This function returns the descriptor number found, or vq->num (which is
2197 * never a valid descriptor number) if none was found. A negative code is
2198 * returned on error. */
2199int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2200 struct iovec iov[], unsigned int iov_size,
2201 unsigned int *out_num, unsigned int *in_num,
2202 struct vhost_log *log, unsigned int *log_num)
2203{
2204 struct vring_desc desc;
2205 unsigned int i, head, found = 0;
2206 u16 last_avail_idx;
2207 __virtio16 avail_idx;
2208 __virtio16 ring_head;
2209 int ret, access;
2210
2211 /* Check it isn't doing very strange things with descriptor numbers. */
2212 last_avail_idx = vq->last_avail_idx;
2213
2214 if (vq->avail_idx == vq->last_avail_idx) {
2215 if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
2216 vq_err(vq, "Failed to access avail idx at %p\n",
2217 &vq->avail->idx);
2218 return -EFAULT;
2219 }
2220 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2221
2222 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2223 vq_err(vq, "Guest moved used index from %u to %u",
2224 last_avail_idx, vq->avail_idx);
2225 return -EFAULT;
2226 }
2227
2228 /* If there's nothing new since last we looked, return
2229 * invalid.
2230 */
2231 if (vq->avail_idx == last_avail_idx)
2232 return vq->num;
2233
2234 /* Only get avail ring entries after they have been
2235 * exposed by guest.
2236 */
2237 smp_rmb();
2238 }
2239
2240 /* Grab the next descriptor number they're advertising, and increment
2241 * the index we've seen. */
2242 if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
2243 vq_err(vq, "Failed to read head: idx %d address %p\n",
2244 last_avail_idx,
2245 &vq->avail->ring[last_avail_idx % vq->num]);
2246 return -EFAULT;
2247 }
2248
2249 head = vhost16_to_cpu(vq, ring_head);
2250
2251 /* If their number is silly, that's an error. */
2252 if (unlikely(head >= vq->num)) {
2253 vq_err(vq, "Guest says index %u > %u is available",
2254 head, vq->num);
2255 return -EINVAL;
2256 }
2257
2258 /* When we start there are none of either input nor output. */
2259 *out_num = *in_num = 0;
2260 if (unlikely(log))
2261 *log_num = 0;
2262
2263 i = head;
2264 do {
2265 unsigned iov_count = *in_num + *out_num;
2266 if (unlikely(i >= vq->num)) {
2267 vq_err(vq, "Desc index is %u > %u, head = %u",
2268 i, vq->num, head);
2269 return -EINVAL;
2270 }
2271 if (unlikely(++found > vq->num)) {
2272 vq_err(vq, "Loop detected: last one at %u "
2273 "vq size %u head %u\n",
2274 i, vq->num, head);
2275 return -EINVAL;
2276 }
2277 ret = vhost_get_desc(vq, &desc, i);
2278 if (unlikely(ret)) {
2279 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2280 i, vq->desc + i);
2281 return -EFAULT;
2282 }
2283 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2284 ret = get_indirect(vq, iov, iov_size,
2285 out_num, in_num,
2286 log, log_num, &desc);
2287 if (unlikely(ret < 0)) {
2288 if (ret != -EAGAIN)
2289 vq_err(vq, "Failure detected "
2290 "in indirect descriptor at idx %d\n", i);
2291 return ret;
2292 }
2293 continue;
2294 }
2295
2296 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2297 access = VHOST_ACCESS_WO;
2298 else
2299 access = VHOST_ACCESS_RO;
2300 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2301 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2302 iov_size - iov_count, access);
2303 if (unlikely(ret < 0)) {
2304 if (ret != -EAGAIN)
2305 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2306 ret, i);
2307 return ret;
2308 }
2309 if (access == VHOST_ACCESS_WO) {
2310 /* If this is an input descriptor,
2311 * increment that count. */
2312 *in_num += ret;
2313 if (unlikely(log && ret)) {
2314 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2315 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2316 ++*log_num;
2317 }
2318 } else {
2319 /* If it's an output descriptor, they're all supposed
2320 * to come before any input descriptors. */
2321 if (unlikely(*in_num)) {
2322 vq_err(vq, "Descriptor has out after in: "
2323 "idx %d\n", i);
2324 return -EINVAL;
2325 }
2326 *out_num += ret;
2327 }
2328 } while ((i = next_desc(vq, &desc)) != -1);
2329
2330 /* On success, increment avail index. */
2331 vq->last_avail_idx++;
2332
2333 /* Assume notifications from guest are disabled at this point,
2334 * if they aren't we would need to update avail_event index. */
2335 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2336 return head;
2337}
2338EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2339
2340/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2341void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2342{
2343 vq->last_avail_idx -= n;
2344}
2345EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2346
2347/* After we've used one of their buffers, we tell them about it. We'll then
2348 * want to notify the guest, using eventfd. */
2349int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2350{
2351 struct vring_used_elem heads = {
2352 cpu_to_vhost32(vq, head),
2353 cpu_to_vhost32(vq, len)
2354 };
2355
2356 return vhost_add_used_n(vq, &heads, 1);
2357}
2358EXPORT_SYMBOL_GPL(vhost_add_used);
2359
2360static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2361 struct vring_used_elem *heads,
2362 unsigned count)
2363{
2364 vring_used_elem_t __user *used;
2365 u16 old, new;
2366 int start;
2367
2368 start = vq->last_used_idx & (vq->num - 1);
2369 used = vq->used->ring + start;
2370 if (vhost_put_used(vq, heads, start, count)) {
2371 vq_err(vq, "Failed to write used");
2372 return -EFAULT;
2373 }
2374 if (unlikely(vq->log_used)) {
2375 /* Make sure data is seen before log. */
2376 smp_wmb();
2377 /* Log used ring entry write. */
2378 log_used(vq, ((void __user *)used - (void __user *)vq->used),
2379 count * sizeof *used);
2380 }
2381 old = vq->last_used_idx;
2382 new = (vq->last_used_idx += count);
2383 /* If the driver never bothers to signal in a very long while,
2384 * used index might wrap around. If that happens, invalidate
2385 * signalled_used index we stored. TODO: make sure driver
2386 * signals at least once in 2^16 and remove this. */
2387 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2388 vq->signalled_used_valid = false;
2389 return 0;
2390}
2391
2392/* After we've used one of their buffers, we tell them about it. We'll then
2393 * want to notify the guest, using eventfd. */
2394int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2395 unsigned count)
2396{
2397 int start, n, r;
2398
2399 start = vq->last_used_idx & (vq->num - 1);
2400 n = vq->num - start;
2401 if (n < count) {
2402 r = __vhost_add_used_n(vq, heads, n);
2403 if (r < 0)
2404 return r;
2405 heads += n;
2406 count -= n;
2407 }
2408 r = __vhost_add_used_n(vq, heads, count);
2409
2410 /* Make sure buffer is written before we update index. */
2411 smp_wmb();
2412 if (vhost_put_used_idx(vq)) {
2413 vq_err(vq, "Failed to increment used idx");
2414 return -EFAULT;
2415 }
2416 if (unlikely(vq->log_used)) {
2417 /* Make sure used idx is seen before log. */
2418 smp_wmb();
2419 /* Log used index update. */
2420 log_used(vq, offsetof(struct vring_used, idx),
2421 sizeof vq->used->idx);
2422 if (vq->log_ctx)
2423 eventfd_signal(vq->log_ctx, 1);
2424 }
2425 return r;
2426}
2427EXPORT_SYMBOL_GPL(vhost_add_used_n);
2428
2429static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2430{
2431 __u16 old, new;
2432 __virtio16 event;
2433 bool v;
2434 /* Flush out used index updates. This is paired
2435 * with the barrier that the Guest executes when enabling
2436 * interrupts. */
2437 smp_mb();
2438
2439 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2440 unlikely(vq->avail_idx == vq->last_avail_idx))
2441 return true;
2442
2443 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2444 __virtio16 flags;
2445 if (vhost_get_avail_flags(vq, &flags)) {
2446 vq_err(vq, "Failed to get flags");
2447 return true;
2448 }
2449 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2450 }
2451 old = vq->signalled_used;
2452 v = vq->signalled_used_valid;
2453 new = vq->signalled_used = vq->last_used_idx;
2454 vq->signalled_used_valid = true;
2455
2456 if (unlikely(!v))
2457 return true;
2458
2459 if (vhost_get_used_event(vq, &event)) {
2460 vq_err(vq, "Failed to get used event idx");
2461 return true;
2462 }
2463 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2464}
2465
2466/* This actually signals the guest, using eventfd. */
2467void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2468{
2469 /* Signal the Guest tell them we used something up. */
2470 if (vq->call_ctx.ctx && vhost_notify(dev, vq))
2471 eventfd_signal(vq->call_ctx.ctx, 1);
2472}
2473EXPORT_SYMBOL_GPL(vhost_signal);
2474
2475/* And here's the combo meal deal. Supersize me! */
2476void vhost_add_used_and_signal(struct vhost_dev *dev,
2477 struct vhost_virtqueue *vq,
2478 unsigned int head, int len)
2479{
2480 vhost_add_used(vq, head, len);
2481 vhost_signal(dev, vq);
2482}
2483EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2484
2485/* multi-buffer version of vhost_add_used_and_signal */
2486void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2487 struct vhost_virtqueue *vq,
2488 struct vring_used_elem *heads, unsigned count)
2489{
2490 vhost_add_used_n(vq, heads, count);
2491 vhost_signal(dev, vq);
2492}
2493EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2494
2495/* return true if we're sure that avaiable ring is empty */
2496bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2497{
2498 __virtio16 avail_idx;
2499 int r;
2500
2501 if (vq->avail_idx != vq->last_avail_idx)
2502 return false;
2503
2504 r = vhost_get_avail_idx(vq, &avail_idx);
2505 if (unlikely(r))
2506 return false;
2507 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2508
2509 return vq->avail_idx == vq->last_avail_idx;
2510}
2511EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2512
2513/* OK, now we need to know about added descriptors. */
2514bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2515{
2516 __virtio16 avail_idx;
2517 int r;
2518
2519 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2520 return false;
2521 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2522 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2523 r = vhost_update_used_flags(vq);
2524 if (r) {
2525 vq_err(vq, "Failed to enable notification at %p: %d\n",
2526 &vq->used->flags, r);
2527 return false;
2528 }
2529 } else {
2530 r = vhost_update_avail_event(vq, vq->avail_idx);
2531 if (r) {
2532 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2533 vhost_avail_event(vq), r);
2534 return false;
2535 }
2536 }
2537 /* They could have slipped one in as we were doing that: make
2538 * sure it's written, then check again. */
2539 smp_mb();
2540 r = vhost_get_avail_idx(vq, &avail_idx);
2541 if (r) {
2542 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2543 &vq->avail->idx, r);
2544 return false;
2545 }
2546
2547 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2548}
2549EXPORT_SYMBOL_GPL(vhost_enable_notify);
2550
2551/* We don't need to be notified again. */
2552void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2553{
2554 int r;
2555
2556 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2557 return;
2558 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2559 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2560 r = vhost_update_used_flags(vq);
2561 if (r)
2562 vq_err(vq, "Failed to disable notification at %p: %d\n",
2563 &vq->used->flags, r);
2564 }
2565}
2566EXPORT_SYMBOL_GPL(vhost_disable_notify);
2567
2568/* Create a new message. */
2569struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2570{
2571 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2572 if (!node)
2573 return NULL;
2574
2575 /* Make sure all padding within the structure is initialized. */
2576 memset(&node->msg, 0, sizeof node->msg);
2577 node->vq = vq;
2578 node->msg.type = type;
2579 return node;
2580}
2581EXPORT_SYMBOL_GPL(vhost_new_msg);
2582
2583void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2584 struct vhost_msg_node *node)
2585{
2586 spin_lock(&dev->iotlb_lock);
2587 list_add_tail(&node->node, head);
2588 spin_unlock(&dev->iotlb_lock);
2589
2590 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2591}
2592EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2593
2594struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2595 struct list_head *head)
2596{
2597 struct vhost_msg_node *node = NULL;
2598
2599 spin_lock(&dev->iotlb_lock);
2600 if (!list_empty(head)) {
2601 node = list_first_entry(head, struct vhost_msg_node,
2602 node);
2603 list_del(&node->node);
2604 }
2605 spin_unlock(&dev->iotlb_lock);
2606
2607 return node;
2608}
2609EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2610
2611void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
2612{
2613 struct vhost_virtqueue *vq;
2614 int i;
2615
2616 mutex_lock(&dev->mutex);
2617 for (i = 0; i < dev->nvqs; ++i) {
2618 vq = dev->vqs[i];
2619 mutex_lock(&vq->mutex);
2620 vq->acked_backend_features = features;
2621 mutex_unlock(&vq->mutex);
2622 }
2623 mutex_unlock(&dev->mutex);
2624}
2625EXPORT_SYMBOL_GPL(vhost_set_backend_features);
2626
2627static int __init vhost_init(void)
2628{
2629 return 0;
2630}
2631
2632static void __exit vhost_exit(void)
2633{
2634}
2635
2636module_init(vhost_init);
2637module_exit(vhost_exit);
2638
2639MODULE_VERSION("0.0.1");
2640MODULE_LICENSE("GPL v2");
2641MODULE_AUTHOR("Michael S. Tsirkin");
2642MODULE_DESCRIPTION("Host kernel accelerator for virtio");