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