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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/mmu_context.h>
18#include <linux/miscdevice.h>
19#include <linux/mutex.h>
20#include <linux/poll.h>
21#include <linux/file.h>
22#include <linux/highmem.h>
23#include <linux/slab.h>
24#include <linux/vmalloc.h>
25#include <linux/kthread.h>
26#include <linux/cgroup.h>
27#include <linux/module.h>
28#include <linux/sort.h>
29#include <linux/sched/mm.h>
30#include <linux/sched/signal.h>
31#include <linux/interval_tree_generic.h>
32#include <linux/nospec.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
52INTERVAL_TREE_DEFINE(struct vhost_umem_node,
53 rb, __u64, __subtree_last,
54 START, LAST, static inline, vhost_umem_interval_tree);
55
56#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
57static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
58{
59 vq->user_be = !virtio_legacy_is_little_endian();
60}
61
62static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
63{
64 vq->user_be = true;
65}
66
67static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
68{
69 vq->user_be = false;
70}
71
72static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
73{
74 struct vhost_vring_state s;
75
76 if (vq->private_data)
77 return -EBUSY;
78
79 if (copy_from_user(&s, argp, sizeof(s)))
80 return -EFAULT;
81
82 if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
83 s.num != VHOST_VRING_BIG_ENDIAN)
84 return -EINVAL;
85
86 if (s.num == VHOST_VRING_BIG_ENDIAN)
87 vhost_enable_cross_endian_big(vq);
88 else
89 vhost_enable_cross_endian_little(vq);
90
91 return 0;
92}
93
94static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
95 int __user *argp)
96{
97 struct vhost_vring_state s = {
98 .index = idx,
99 .num = vq->user_be
100 };
101
102 if (copy_to_user(argp, &s, sizeof(s)))
103 return -EFAULT;
104
105 return 0;
106}
107
108static void vhost_init_is_le(struct vhost_virtqueue *vq)
109{
110 /* Note for legacy virtio: user_be is initialized at reset time
111 * according to the host endianness. If userspace does not set an
112 * explicit endianness, the default behavior is native endian, as
113 * expected by legacy virtio.
114 */
115 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
116}
117#else
118static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
119{
120}
121
122static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
123{
124 return -ENOIOCTLCMD;
125}
126
127static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
128 int __user *argp)
129{
130 return -ENOIOCTLCMD;
131}
132
133static void vhost_init_is_le(struct vhost_virtqueue *vq)
134{
135 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
136 || virtio_legacy_is_little_endian();
137}
138#endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
139
140static void vhost_reset_is_le(struct vhost_virtqueue *vq)
141{
142 vhost_init_is_le(vq);
143}
144
145struct vhost_flush_struct {
146 struct vhost_work work;
147 struct completion wait_event;
148};
149
150static void vhost_flush_work(struct vhost_work *work)
151{
152 struct vhost_flush_struct *s;
153
154 s = container_of(work, struct vhost_flush_struct, work);
155 complete(&s->wait_event);
156}
157
158static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
159 poll_table *pt)
160{
161 struct vhost_poll *poll;
162
163 poll = container_of(pt, struct vhost_poll, table);
164 poll->wqh = wqh;
165 add_wait_queue(wqh, &poll->wait);
166}
167
168static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
169 void *key)
170{
171 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
172
173 if (!(key_to_poll(key) & poll->mask))
174 return 0;
175
176 vhost_poll_queue(poll);
177 return 0;
178}
179
180void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
181{
182 clear_bit(VHOST_WORK_QUEUED, &work->flags);
183 work->fn = fn;
184}
185EXPORT_SYMBOL_GPL(vhost_work_init);
186
187/* Init poll structure */
188void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
189 __poll_t mask, struct vhost_dev *dev)
190{
191 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
192 init_poll_funcptr(&poll->table, vhost_poll_func);
193 poll->mask = mask;
194 poll->dev = dev;
195 poll->wqh = NULL;
196
197 vhost_work_init(&poll->work, fn);
198}
199EXPORT_SYMBOL_GPL(vhost_poll_init);
200
201/* Start polling a file. We add ourselves to file's wait queue. The caller must
202 * keep a reference to a file until after vhost_poll_stop is called. */
203int vhost_poll_start(struct vhost_poll *poll, struct file *file)
204{
205 __poll_t mask;
206
207 if (poll->wqh)
208 return 0;
209
210 mask = vfs_poll(file, &poll->table);
211 if (mask)
212 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
213 if (mask & EPOLLERR) {
214 vhost_poll_stop(poll);
215 return -EINVAL;
216 }
217
218 return 0;
219}
220EXPORT_SYMBOL_GPL(vhost_poll_start);
221
222/* Stop polling a file. After this function returns, it becomes safe to drop the
223 * file reference. You must also flush afterwards. */
224void vhost_poll_stop(struct vhost_poll *poll)
225{
226 if (poll->wqh) {
227 remove_wait_queue(poll->wqh, &poll->wait);
228 poll->wqh = NULL;
229 }
230}
231EXPORT_SYMBOL_GPL(vhost_poll_stop);
232
233void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
234{
235 struct vhost_flush_struct flush;
236
237 if (dev->worker) {
238 init_completion(&flush.wait_event);
239 vhost_work_init(&flush.work, vhost_flush_work);
240
241 vhost_work_queue(dev, &flush.work);
242 wait_for_completion(&flush.wait_event);
243 }
244}
245EXPORT_SYMBOL_GPL(vhost_work_flush);
246
247/* Flush any work that has been scheduled. When calling this, don't hold any
248 * locks that are also used by the callback. */
249void vhost_poll_flush(struct vhost_poll *poll)
250{
251 vhost_work_flush(poll->dev, &poll->work);
252}
253EXPORT_SYMBOL_GPL(vhost_poll_flush);
254
255void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
256{
257 if (!dev->worker)
258 return;
259
260 if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
261 /* We can only add the work to the list after we're
262 * sure it was not in the list.
263 * test_and_set_bit() implies a memory barrier.
264 */
265 llist_add(&work->node, &dev->work_list);
266 wake_up_process(dev->worker);
267 }
268}
269EXPORT_SYMBOL_GPL(vhost_work_queue);
270
271/* A lockless hint for busy polling code to exit the loop */
272bool vhost_has_work(struct vhost_dev *dev)
273{
274 return !llist_empty(&dev->work_list);
275}
276EXPORT_SYMBOL_GPL(vhost_has_work);
277
278void vhost_poll_queue(struct vhost_poll *poll)
279{
280 vhost_work_queue(poll->dev, &poll->work);
281}
282EXPORT_SYMBOL_GPL(vhost_poll_queue);
283
284static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
285{
286 int j;
287
288 for (j = 0; j < VHOST_NUM_ADDRS; j++)
289 vq->meta_iotlb[j] = NULL;
290}
291
292static void vhost_vq_meta_reset(struct vhost_dev *d)
293{
294 int i;
295
296 for (i = 0; i < d->nvqs; ++i)
297 __vhost_vq_meta_reset(d->vqs[i]);
298}
299
300static void vhost_vq_reset(struct vhost_dev *dev,
301 struct vhost_virtqueue *vq)
302{
303 vq->num = 1;
304 vq->desc = NULL;
305 vq->avail = NULL;
306 vq->used = NULL;
307 vq->last_avail_idx = 0;
308 vq->avail_idx = 0;
309 vq->last_used_idx = 0;
310 vq->signalled_used = 0;
311 vq->signalled_used_valid = false;
312 vq->used_flags = 0;
313 vq->log_used = false;
314 vq->log_addr = -1ull;
315 vq->private_data = NULL;
316 vq->acked_features = 0;
317 vq->acked_backend_features = 0;
318 vq->log_base = NULL;
319 vq->error_ctx = NULL;
320 vq->kick = NULL;
321 vq->call_ctx = NULL;
322 vq->log_ctx = NULL;
323 vhost_reset_is_le(vq);
324 vhost_disable_cross_endian(vq);
325 vq->busyloop_timeout = 0;
326 vq->umem = NULL;
327 vq->iotlb = NULL;
328 __vhost_vq_meta_reset(vq);
329}
330
331static int vhost_worker(void *data)
332{
333 struct vhost_dev *dev = data;
334 struct vhost_work *work, *work_next;
335 struct llist_node *node;
336 mm_segment_t oldfs = get_fs();
337
338 set_fs(USER_DS);
339 use_mm(dev->mm);
340
341 for (;;) {
342 /* mb paired w/ kthread_stop */
343 set_current_state(TASK_INTERRUPTIBLE);
344
345 if (kthread_should_stop()) {
346 __set_current_state(TASK_RUNNING);
347 break;
348 }
349
350 node = llist_del_all(&dev->work_list);
351 if (!node)
352 schedule();
353
354 node = llist_reverse_order(node);
355 /* make sure flag is seen after deletion */
356 smp_wmb();
357 llist_for_each_entry_safe(work, work_next, node, node) {
358 clear_bit(VHOST_WORK_QUEUED, &work->flags);
359 __set_current_state(TASK_RUNNING);
360 work->fn(work);
361 if (need_resched())
362 schedule();
363 }
364 }
365 unuse_mm(dev->mm);
366 set_fs(oldfs);
367 return 0;
368}
369
370static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
371{
372 kfree(vq->indirect);
373 vq->indirect = NULL;
374 kfree(vq->log);
375 vq->log = NULL;
376 kfree(vq->heads);
377 vq->heads = NULL;
378}
379
380/* Helper to allocate iovec buffers for all vqs. */
381static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
382{
383 struct vhost_virtqueue *vq;
384 int i;
385
386 for (i = 0; i < dev->nvqs; ++i) {
387 vq = dev->vqs[i];
388 vq->indirect = kmalloc_array(UIO_MAXIOV,
389 sizeof(*vq->indirect),
390 GFP_KERNEL);
391 vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
392 GFP_KERNEL);
393 vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
394 GFP_KERNEL);
395 if (!vq->indirect || !vq->log || !vq->heads)
396 goto err_nomem;
397 }
398 return 0;
399
400err_nomem:
401 for (; i >= 0; --i)
402 vhost_vq_free_iovecs(dev->vqs[i]);
403 return -ENOMEM;
404}
405
406static void vhost_dev_free_iovecs(struct vhost_dev *dev)
407{
408 int i;
409
410 for (i = 0; i < dev->nvqs; ++i)
411 vhost_vq_free_iovecs(dev->vqs[i]);
412}
413
414bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
415 int pkts, int total_len)
416{
417 struct vhost_dev *dev = vq->dev;
418
419 if ((dev->byte_weight && total_len >= dev->byte_weight) ||
420 pkts >= dev->weight) {
421 vhost_poll_queue(&vq->poll);
422 return true;
423 }
424
425 return false;
426}
427EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
428
429static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
430 unsigned int num)
431{
432 size_t event __maybe_unused =
433 vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
434
435 return sizeof(*vq->avail) +
436 sizeof(*vq->avail->ring) * num + event;
437}
438
439static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
440 unsigned int num)
441{
442 size_t event __maybe_unused =
443 vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
444
445 return sizeof(*vq->used) +
446 sizeof(*vq->used->ring) * num + event;
447}
448
449static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
450 unsigned int num)
451{
452 return sizeof(*vq->desc) * num;
453}
454
455void vhost_dev_init(struct vhost_dev *dev,
456 struct vhost_virtqueue **vqs, int nvqs,
457 int iov_limit, int weight, int byte_weight)
458{
459 struct vhost_virtqueue *vq;
460 int i;
461
462 dev->vqs = vqs;
463 dev->nvqs = nvqs;
464 mutex_init(&dev->mutex);
465 dev->log_ctx = NULL;
466 dev->umem = NULL;
467 dev->iotlb = NULL;
468 dev->mm = NULL;
469 dev->worker = NULL;
470 dev->iov_limit = iov_limit;
471 dev->weight = weight;
472 dev->byte_weight = byte_weight;
473 init_llist_head(&dev->work_list);
474 init_waitqueue_head(&dev->wait);
475 INIT_LIST_HEAD(&dev->read_list);
476 INIT_LIST_HEAD(&dev->pending_list);
477 spin_lock_init(&dev->iotlb_lock);
478
479
480 for (i = 0; i < dev->nvqs; ++i) {
481 vq = dev->vqs[i];
482 vq->log = NULL;
483 vq->indirect = NULL;
484 vq->heads = NULL;
485 vq->dev = dev;
486 mutex_init(&vq->mutex);
487 vhost_vq_reset(dev, vq);
488 if (vq->handle_kick)
489 vhost_poll_init(&vq->poll, vq->handle_kick,
490 EPOLLIN, dev);
491 }
492}
493EXPORT_SYMBOL_GPL(vhost_dev_init);
494
495/* Caller should have device mutex */
496long vhost_dev_check_owner(struct vhost_dev *dev)
497{
498 /* Are you the owner? If not, I don't think you mean to do that */
499 return dev->mm == current->mm ? 0 : -EPERM;
500}
501EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
502
503struct vhost_attach_cgroups_struct {
504 struct vhost_work work;
505 struct task_struct *owner;
506 int ret;
507};
508
509static void vhost_attach_cgroups_work(struct vhost_work *work)
510{
511 struct vhost_attach_cgroups_struct *s;
512
513 s = container_of(work, struct vhost_attach_cgroups_struct, work);
514 s->ret = cgroup_attach_task_all(s->owner, current);
515}
516
517static int vhost_attach_cgroups(struct vhost_dev *dev)
518{
519 struct vhost_attach_cgroups_struct attach;
520
521 attach.owner = current;
522 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
523 vhost_work_queue(dev, &attach.work);
524 vhost_work_flush(dev, &attach.work);
525 return attach.ret;
526}
527
528/* Caller should have device mutex */
529bool vhost_dev_has_owner(struct vhost_dev *dev)
530{
531 return dev->mm;
532}
533EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
534
535/* Caller should have device mutex */
536long vhost_dev_set_owner(struct vhost_dev *dev)
537{
538 struct task_struct *worker;
539 int err;
540
541 /* Is there an owner already? */
542 if (vhost_dev_has_owner(dev)) {
543 err = -EBUSY;
544 goto err_mm;
545 }
546
547 /* No owner, become one */
548 dev->mm = get_task_mm(current);
549 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
550 if (IS_ERR(worker)) {
551 err = PTR_ERR(worker);
552 goto err_worker;
553 }
554
555 dev->worker = worker;
556 wake_up_process(worker); /* avoid contributing to loadavg */
557
558 err = vhost_attach_cgroups(dev);
559 if (err)
560 goto err_cgroup;
561
562 err = vhost_dev_alloc_iovecs(dev);
563 if (err)
564 goto err_cgroup;
565
566 return 0;
567err_cgroup:
568 kthread_stop(worker);
569 dev->worker = NULL;
570err_worker:
571 if (dev->mm)
572 mmput(dev->mm);
573 dev->mm = NULL;
574err_mm:
575 return err;
576}
577EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
578
579struct vhost_umem *vhost_dev_reset_owner_prepare(void)
580{
581 return kvzalloc(sizeof(struct vhost_umem), GFP_KERNEL);
582}
583EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
584
585/* Caller should have device mutex */
586void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
587{
588 int i;
589
590 vhost_dev_cleanup(dev);
591
592 /* Restore memory to default empty mapping. */
593 INIT_LIST_HEAD(&umem->umem_list);
594 dev->umem = umem;
595 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
596 * VQs aren't running.
597 */
598 for (i = 0; i < dev->nvqs; ++i)
599 dev->vqs[i]->umem = umem;
600}
601EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
602
603void vhost_dev_stop(struct vhost_dev *dev)
604{
605 int i;
606
607 for (i = 0; i < dev->nvqs; ++i) {
608 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
609 vhost_poll_stop(&dev->vqs[i]->poll);
610 vhost_poll_flush(&dev->vqs[i]->poll);
611 }
612 }
613}
614EXPORT_SYMBOL_GPL(vhost_dev_stop);
615
616static void vhost_umem_free(struct vhost_umem *umem,
617 struct vhost_umem_node *node)
618{
619 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
620 list_del(&node->link);
621 kfree(node);
622 umem->numem--;
623}
624
625static void vhost_umem_clean(struct vhost_umem *umem)
626{
627 struct vhost_umem_node *node, *tmp;
628
629 if (!umem)
630 return;
631
632 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
633 vhost_umem_free(umem, node);
634
635 kvfree(umem);
636}
637
638static void vhost_clear_msg(struct vhost_dev *dev)
639{
640 struct vhost_msg_node *node, *n;
641
642 spin_lock(&dev->iotlb_lock);
643
644 list_for_each_entry_safe(node, n, &dev->read_list, node) {
645 list_del(&node->node);
646 kfree(node);
647 }
648
649 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
650 list_del(&node->node);
651 kfree(node);
652 }
653
654 spin_unlock(&dev->iotlb_lock);
655}
656
657void vhost_dev_cleanup(struct vhost_dev *dev)
658{
659 int i;
660
661 for (i = 0; i < dev->nvqs; ++i) {
662 if (dev->vqs[i]->error_ctx)
663 eventfd_ctx_put(dev->vqs[i]->error_ctx);
664 if (dev->vqs[i]->kick)
665 fput(dev->vqs[i]->kick);
666 if (dev->vqs[i]->call_ctx)
667 eventfd_ctx_put(dev->vqs[i]->call_ctx);
668 vhost_vq_reset(dev, dev->vqs[i]);
669 }
670 vhost_dev_free_iovecs(dev);
671 if (dev->log_ctx)
672 eventfd_ctx_put(dev->log_ctx);
673 dev->log_ctx = NULL;
674 /* No one will access memory at this point */
675 vhost_umem_clean(dev->umem);
676 dev->umem = NULL;
677 vhost_umem_clean(dev->iotlb);
678 dev->iotlb = NULL;
679 vhost_clear_msg(dev);
680 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
681 WARN_ON(!llist_empty(&dev->work_list));
682 if (dev->worker) {
683 kthread_stop(dev->worker);
684 dev->worker = NULL;
685 }
686 if (dev->mm)
687 mmput(dev->mm);
688 dev->mm = NULL;
689}
690EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
691
692static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
693{
694 u64 a = addr / VHOST_PAGE_SIZE / 8;
695
696 /* Make sure 64 bit math will not overflow. */
697 if (a > ULONG_MAX - (unsigned long)log_base ||
698 a + (unsigned long)log_base > ULONG_MAX)
699 return false;
700
701 return access_ok(log_base + a,
702 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
703}
704
705static bool vhost_overflow(u64 uaddr, u64 size)
706{
707 /* Make sure 64 bit math will not overflow. */
708 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
709}
710
711/* Caller should have vq mutex and device mutex. */
712static bool vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
713 int log_all)
714{
715 struct vhost_umem_node *node;
716
717 if (!umem)
718 return false;
719
720 list_for_each_entry(node, &umem->umem_list, link) {
721 unsigned long a = node->userspace_addr;
722
723 if (vhost_overflow(node->userspace_addr, node->size))
724 return false;
725
726
727 if (!access_ok((void __user *)a,
728 node->size))
729 return false;
730 else if (log_all && !log_access_ok(log_base,
731 node->start,
732 node->size))
733 return false;
734 }
735 return true;
736}
737
738static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
739 u64 addr, unsigned int size,
740 int type)
741{
742 const struct vhost_umem_node *node = vq->meta_iotlb[type];
743
744 if (!node)
745 return NULL;
746
747 return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
748}
749
750/* Can we switch to this memory table? */
751/* Caller should have device mutex but not vq mutex */
752static bool memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
753 int log_all)
754{
755 int i;
756
757 for (i = 0; i < d->nvqs; ++i) {
758 bool ok;
759 bool log;
760
761 mutex_lock(&d->vqs[i]->mutex);
762 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
763 /* If ring is inactive, will check when it's enabled. */
764 if (d->vqs[i]->private_data)
765 ok = vq_memory_access_ok(d->vqs[i]->log_base,
766 umem, log);
767 else
768 ok = true;
769 mutex_unlock(&d->vqs[i]->mutex);
770 if (!ok)
771 return false;
772 }
773 return true;
774}
775
776static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
777 struct iovec iov[], int iov_size, int access);
778
779static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
780 const void *from, unsigned size)
781{
782 int ret;
783
784 if (!vq->iotlb)
785 return __copy_to_user(to, from, size);
786 else {
787 /* This function should be called after iotlb
788 * prefetch, which means we're sure that all vq
789 * could be access through iotlb. So -EAGAIN should
790 * not happen in this case.
791 */
792 struct iov_iter t;
793 void __user *uaddr = vhost_vq_meta_fetch(vq,
794 (u64)(uintptr_t)to, size,
795 VHOST_ADDR_USED);
796
797 if (uaddr)
798 return __copy_to_user(uaddr, from, size);
799
800 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
801 ARRAY_SIZE(vq->iotlb_iov),
802 VHOST_ACCESS_WO);
803 if (ret < 0)
804 goto out;
805 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
806 ret = copy_to_iter(from, size, &t);
807 if (ret == size)
808 ret = 0;
809 }
810out:
811 return ret;
812}
813
814static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
815 void __user *from, unsigned size)
816{
817 int ret;
818
819 if (!vq->iotlb)
820 return __copy_from_user(to, from, size);
821 else {
822 /* This function should be called after iotlb
823 * prefetch, which means we're sure that vq
824 * could be access through iotlb. So -EAGAIN should
825 * not happen in this case.
826 */
827 void __user *uaddr = vhost_vq_meta_fetch(vq,
828 (u64)(uintptr_t)from, size,
829 VHOST_ADDR_DESC);
830 struct iov_iter f;
831
832 if (uaddr)
833 return __copy_from_user(to, uaddr, size);
834
835 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
836 ARRAY_SIZE(vq->iotlb_iov),
837 VHOST_ACCESS_RO);
838 if (ret < 0) {
839 vq_err(vq, "IOTLB translation failure: uaddr "
840 "%p size 0x%llx\n", from,
841 (unsigned long long) size);
842 goto out;
843 }
844 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
845 ret = copy_from_iter(to, size, &f);
846 if (ret == size)
847 ret = 0;
848 }
849
850out:
851 return ret;
852}
853
854static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
855 void __user *addr, unsigned int size,
856 int type)
857{
858 int ret;
859
860 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
861 ARRAY_SIZE(vq->iotlb_iov),
862 VHOST_ACCESS_RO);
863 if (ret < 0) {
864 vq_err(vq, "IOTLB translation failure: uaddr "
865 "%p size 0x%llx\n", addr,
866 (unsigned long long) size);
867 return NULL;
868 }
869
870 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
871 vq_err(vq, "Non atomic userspace memory access: uaddr "
872 "%p size 0x%llx\n", addr,
873 (unsigned long long) size);
874 return NULL;
875 }
876
877 return vq->iotlb_iov[0].iov_base;
878}
879
880/* This function should be called after iotlb
881 * prefetch, which means we're sure that vq
882 * could be access through iotlb. So -EAGAIN should
883 * not happen in this case.
884 */
885static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
886 void *addr, unsigned int size,
887 int type)
888{
889 void __user *uaddr = vhost_vq_meta_fetch(vq,
890 (u64)(uintptr_t)addr, size, type);
891 if (uaddr)
892 return uaddr;
893
894 return __vhost_get_user_slow(vq, addr, size, type);
895}
896
897#define vhost_put_user(vq, x, ptr) \
898({ \
899 int ret = -EFAULT; \
900 if (!vq->iotlb) { \
901 ret = __put_user(x, ptr); \
902 } else { \
903 __typeof__(ptr) to = \
904 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
905 sizeof(*ptr), VHOST_ADDR_USED); \
906 if (to != NULL) \
907 ret = __put_user(x, to); \
908 else \
909 ret = -EFAULT; \
910 } \
911 ret; \
912})
913
914static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
915{
916 return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
917 vhost_avail_event(vq));
918}
919
920static inline int vhost_put_used(struct vhost_virtqueue *vq,
921 struct vring_used_elem *head, int idx,
922 int count)
923{
924 return vhost_copy_to_user(vq, vq->used->ring + idx, head,
925 count * sizeof(*head));
926}
927
928static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
929
930{
931 return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
932 &vq->used->flags);
933}
934
935static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
936
937{
938 return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
939 &vq->used->idx);
940}
941
942#define vhost_get_user(vq, x, ptr, type) \
943({ \
944 int ret; \
945 if (!vq->iotlb) { \
946 ret = __get_user(x, ptr); \
947 } else { \
948 __typeof__(ptr) from = \
949 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
950 sizeof(*ptr), \
951 type); \
952 if (from != NULL) \
953 ret = __get_user(x, from); \
954 else \
955 ret = -EFAULT; \
956 } \
957 ret; \
958})
959
960#define vhost_get_avail(vq, x, ptr) \
961 vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
962
963#define vhost_get_used(vq, x, ptr) \
964 vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
965
966static void vhost_dev_lock_vqs(struct vhost_dev *d)
967{
968 int i = 0;
969 for (i = 0; i < d->nvqs; ++i)
970 mutex_lock_nested(&d->vqs[i]->mutex, i);
971}
972
973static void vhost_dev_unlock_vqs(struct vhost_dev *d)
974{
975 int i = 0;
976 for (i = 0; i < d->nvqs; ++i)
977 mutex_unlock(&d->vqs[i]->mutex);
978}
979
980static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
981 __virtio16 *idx)
982{
983 return vhost_get_avail(vq, *idx, &vq->avail->idx);
984}
985
986static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
987 __virtio16 *head, int idx)
988{
989 return vhost_get_avail(vq, *head,
990 &vq->avail->ring[idx & (vq->num - 1)]);
991}
992
993static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
994 __virtio16 *flags)
995{
996 return vhost_get_avail(vq, *flags, &vq->avail->flags);
997}
998
999static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
1000 __virtio16 *event)
1001{
1002 return vhost_get_avail(vq, *event, vhost_used_event(vq));
1003}
1004
1005static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
1006 __virtio16 *idx)
1007{
1008 return vhost_get_used(vq, *idx, &vq->used->idx);
1009}
1010
1011static inline int vhost_get_desc(struct vhost_virtqueue *vq,
1012 struct vring_desc *desc, int idx)
1013{
1014 return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
1015}
1016
1017static int vhost_new_umem_range(struct vhost_umem *umem,
1018 u64 start, u64 size, u64 end,
1019 u64 userspace_addr, int perm)
1020{
1021 struct vhost_umem_node *tmp, *node;
1022
1023 if (!size)
1024 return -EFAULT;
1025
1026 node = kmalloc(sizeof(*node), GFP_ATOMIC);
1027 if (!node)
1028 return -ENOMEM;
1029
1030 if (umem->numem == max_iotlb_entries) {
1031 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
1032 vhost_umem_free(umem, tmp);
1033 }
1034
1035 node->start = start;
1036 node->size = size;
1037 node->last = end;
1038 node->userspace_addr = userspace_addr;
1039 node->perm = perm;
1040 INIT_LIST_HEAD(&node->link);
1041 list_add_tail(&node->link, &umem->umem_list);
1042 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
1043 umem->numem++;
1044
1045 return 0;
1046}
1047
1048static void vhost_del_umem_range(struct vhost_umem *umem,
1049 u64 start, u64 end)
1050{
1051 struct vhost_umem_node *node;
1052
1053 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1054 start, end)))
1055 vhost_umem_free(umem, node);
1056}
1057
1058static void vhost_iotlb_notify_vq(struct vhost_dev *d,
1059 struct vhost_iotlb_msg *msg)
1060{
1061 struct vhost_msg_node *node, *n;
1062
1063 spin_lock(&d->iotlb_lock);
1064
1065 list_for_each_entry_safe(node, n, &d->pending_list, node) {
1066 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
1067 if (msg->iova <= vq_msg->iova &&
1068 msg->iova + msg->size - 1 >= vq_msg->iova &&
1069 vq_msg->type == VHOST_IOTLB_MISS) {
1070 vhost_poll_queue(&node->vq->poll);
1071 list_del(&node->node);
1072 kfree(node);
1073 }
1074 }
1075
1076 spin_unlock(&d->iotlb_lock);
1077}
1078
1079static bool umem_access_ok(u64 uaddr, u64 size, int access)
1080{
1081 unsigned long a = uaddr;
1082
1083 /* Make sure 64 bit math will not overflow. */
1084 if (vhost_overflow(uaddr, size))
1085 return false;
1086
1087 if ((access & VHOST_ACCESS_RO) &&
1088 !access_ok((void __user *)a, size))
1089 return false;
1090 if ((access & VHOST_ACCESS_WO) &&
1091 !access_ok((void __user *)a, size))
1092 return false;
1093 return true;
1094}
1095
1096static int vhost_process_iotlb_msg(struct vhost_dev *dev,
1097 struct vhost_iotlb_msg *msg)
1098{
1099 int ret = 0;
1100
1101 mutex_lock(&dev->mutex);
1102 vhost_dev_lock_vqs(dev);
1103 switch (msg->type) {
1104 case VHOST_IOTLB_UPDATE:
1105 if (!dev->iotlb) {
1106 ret = -EFAULT;
1107 break;
1108 }
1109 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1110 ret = -EFAULT;
1111 break;
1112 }
1113 vhost_vq_meta_reset(dev);
1114 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
1115 msg->iova + msg->size - 1,
1116 msg->uaddr, msg->perm)) {
1117 ret = -ENOMEM;
1118 break;
1119 }
1120 vhost_iotlb_notify_vq(dev, msg);
1121 break;
1122 case VHOST_IOTLB_INVALIDATE:
1123 if (!dev->iotlb) {
1124 ret = -EFAULT;
1125 break;
1126 }
1127 vhost_vq_meta_reset(dev);
1128 vhost_del_umem_range(dev->iotlb, msg->iova,
1129 msg->iova + msg->size - 1);
1130 break;
1131 default:
1132 ret = -EINVAL;
1133 break;
1134 }
1135
1136 vhost_dev_unlock_vqs(dev);
1137 mutex_unlock(&dev->mutex);
1138
1139 return ret;
1140}
1141ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1142 struct iov_iter *from)
1143{
1144 struct vhost_iotlb_msg msg;
1145 size_t offset;
1146 int type, ret;
1147
1148 ret = copy_from_iter(&type, sizeof(type), from);
1149 if (ret != sizeof(type)) {
1150 ret = -EINVAL;
1151 goto done;
1152 }
1153
1154 switch (type) {
1155 case VHOST_IOTLB_MSG:
1156 /* There maybe a hole after type for V1 message type,
1157 * so skip it here.
1158 */
1159 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1160 break;
1161 case VHOST_IOTLB_MSG_V2:
1162 offset = sizeof(__u32);
1163 break;
1164 default:
1165 ret = -EINVAL;
1166 goto done;
1167 }
1168
1169 iov_iter_advance(from, offset);
1170 ret = copy_from_iter(&msg, sizeof(msg), from);
1171 if (ret != sizeof(msg)) {
1172 ret = -EINVAL;
1173 goto done;
1174 }
1175 if (vhost_process_iotlb_msg(dev, &msg)) {
1176 ret = -EFAULT;
1177 goto done;
1178 }
1179
1180 ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1181 sizeof(struct vhost_msg_v2);
1182done:
1183 return ret;
1184}
1185EXPORT_SYMBOL(vhost_chr_write_iter);
1186
1187__poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1188 poll_table *wait)
1189{
1190 __poll_t mask = 0;
1191
1192 poll_wait(file, &dev->wait, wait);
1193
1194 if (!list_empty(&dev->read_list))
1195 mask |= EPOLLIN | EPOLLRDNORM;
1196
1197 return mask;
1198}
1199EXPORT_SYMBOL(vhost_chr_poll);
1200
1201ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1202 int noblock)
1203{
1204 DEFINE_WAIT(wait);
1205 struct vhost_msg_node *node;
1206 ssize_t ret = 0;
1207 unsigned size = sizeof(struct vhost_msg);
1208
1209 if (iov_iter_count(to) < size)
1210 return 0;
1211
1212 while (1) {
1213 if (!noblock)
1214 prepare_to_wait(&dev->wait, &wait,
1215 TASK_INTERRUPTIBLE);
1216
1217 node = vhost_dequeue_msg(dev, &dev->read_list);
1218 if (node)
1219 break;
1220 if (noblock) {
1221 ret = -EAGAIN;
1222 break;
1223 }
1224 if (signal_pending(current)) {
1225 ret = -ERESTARTSYS;
1226 break;
1227 }
1228 if (!dev->iotlb) {
1229 ret = -EBADFD;
1230 break;
1231 }
1232
1233 schedule();
1234 }
1235
1236 if (!noblock)
1237 finish_wait(&dev->wait, &wait);
1238
1239 if (node) {
1240 struct vhost_iotlb_msg *msg;
1241 void *start = &node->msg;
1242
1243 switch (node->msg.type) {
1244 case VHOST_IOTLB_MSG:
1245 size = sizeof(node->msg);
1246 msg = &node->msg.iotlb;
1247 break;
1248 case VHOST_IOTLB_MSG_V2:
1249 size = sizeof(node->msg_v2);
1250 msg = &node->msg_v2.iotlb;
1251 break;
1252 default:
1253 BUG();
1254 break;
1255 }
1256
1257 ret = copy_to_iter(start, size, to);
1258 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1259 kfree(node);
1260 return ret;
1261 }
1262 vhost_enqueue_msg(dev, &dev->pending_list, node);
1263 }
1264
1265 return ret;
1266}
1267EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1268
1269static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1270{
1271 struct vhost_dev *dev = vq->dev;
1272 struct vhost_msg_node *node;
1273 struct vhost_iotlb_msg *msg;
1274 bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1275
1276 node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1277 if (!node)
1278 return -ENOMEM;
1279
1280 if (v2) {
1281 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1282 msg = &node->msg_v2.iotlb;
1283 } else {
1284 msg = &node->msg.iotlb;
1285 }
1286
1287 msg->type = VHOST_IOTLB_MISS;
1288 msg->iova = iova;
1289 msg->perm = access;
1290
1291 vhost_enqueue_msg(dev, &dev->read_list, node);
1292
1293 return 0;
1294}
1295
1296static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1297 struct vring_desc __user *desc,
1298 struct vring_avail __user *avail,
1299 struct vring_used __user *used)
1300
1301{
1302 return access_ok(desc, vhost_get_desc_size(vq, num)) &&
1303 access_ok(avail, vhost_get_avail_size(vq, num)) &&
1304 access_ok(used, vhost_get_used_size(vq, num));
1305}
1306
1307static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1308 const struct vhost_umem_node *node,
1309 int type)
1310{
1311 int access = (type == VHOST_ADDR_USED) ?
1312 VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1313
1314 if (likely(node->perm & access))
1315 vq->meta_iotlb[type] = node;
1316}
1317
1318static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1319 int access, u64 addr, u64 len, int type)
1320{
1321 const struct vhost_umem_node *node;
1322 struct vhost_umem *umem = vq->iotlb;
1323 u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1324
1325 if (vhost_vq_meta_fetch(vq, addr, len, type))
1326 return true;
1327
1328 while (len > s) {
1329 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1330 addr,
1331 last);
1332 if (node == NULL || node->start > addr) {
1333 vhost_iotlb_miss(vq, addr, access);
1334 return false;
1335 } else if (!(node->perm & access)) {
1336 /* Report the possible access violation by
1337 * request another translation from userspace.
1338 */
1339 return false;
1340 }
1341
1342 size = node->size - addr + node->start;
1343
1344 if (orig_addr == addr && size >= len)
1345 vhost_vq_meta_update(vq, node, type);
1346
1347 s += size;
1348 addr += size;
1349 }
1350
1351 return true;
1352}
1353
1354int vq_meta_prefetch(struct vhost_virtqueue *vq)
1355{
1356 unsigned int num = vq->num;
1357
1358 if (!vq->iotlb)
1359 return 1;
1360
1361 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1362 vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
1363 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1364 vhost_get_avail_size(vq, num),
1365 VHOST_ADDR_AVAIL) &&
1366 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1367 vhost_get_used_size(vq, num), VHOST_ADDR_USED);
1368}
1369EXPORT_SYMBOL_GPL(vq_meta_prefetch);
1370
1371/* Can we log writes? */
1372/* Caller should have device mutex but not vq mutex */
1373bool vhost_log_access_ok(struct vhost_dev *dev)
1374{
1375 return memory_access_ok(dev, dev->umem, 1);
1376}
1377EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1378
1379/* Verify access for write logging. */
1380/* Caller should have vq mutex and device mutex */
1381static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1382 void __user *log_base)
1383{
1384 return vq_memory_access_ok(log_base, vq->umem,
1385 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1386 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1387 vhost_get_used_size(vq, vq->num)));
1388}
1389
1390/* Can we start vq? */
1391/* Caller should have vq mutex and device mutex */
1392bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1393{
1394 if (!vq_log_access_ok(vq, vq->log_base))
1395 return false;
1396
1397 /* Access validation occurs at prefetch time with IOTLB */
1398 if (vq->iotlb)
1399 return true;
1400
1401 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1402}
1403EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1404
1405static struct vhost_umem *vhost_umem_alloc(void)
1406{
1407 struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1408
1409 if (!umem)
1410 return NULL;
1411
1412 umem->umem_tree = RB_ROOT_CACHED;
1413 umem->numem = 0;
1414 INIT_LIST_HEAD(&umem->umem_list);
1415
1416 return umem;
1417}
1418
1419static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1420{
1421 struct vhost_memory mem, *newmem;
1422 struct vhost_memory_region *region;
1423 struct vhost_umem *newumem, *oldumem;
1424 unsigned long size = offsetof(struct vhost_memory, regions);
1425 int i;
1426
1427 if (copy_from_user(&mem, m, size))
1428 return -EFAULT;
1429 if (mem.padding)
1430 return -EOPNOTSUPP;
1431 if (mem.nregions > max_mem_regions)
1432 return -E2BIG;
1433 newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1434 GFP_KERNEL);
1435 if (!newmem)
1436 return -ENOMEM;
1437
1438 memcpy(newmem, &mem, size);
1439 if (copy_from_user(newmem->regions, m->regions,
1440 mem.nregions * sizeof *m->regions)) {
1441 kvfree(newmem);
1442 return -EFAULT;
1443 }
1444
1445 newumem = vhost_umem_alloc();
1446 if (!newumem) {
1447 kvfree(newmem);
1448 return -ENOMEM;
1449 }
1450
1451 for (region = newmem->regions;
1452 region < newmem->regions + mem.nregions;
1453 region++) {
1454 if (vhost_new_umem_range(newumem,
1455 region->guest_phys_addr,
1456 region->memory_size,
1457 region->guest_phys_addr +
1458 region->memory_size - 1,
1459 region->userspace_addr,
1460 VHOST_ACCESS_RW))
1461 goto err;
1462 }
1463
1464 if (!memory_access_ok(d, newumem, 0))
1465 goto err;
1466
1467 oldumem = d->umem;
1468 d->umem = newumem;
1469
1470 /* All memory accesses are done under some VQ mutex. */
1471 for (i = 0; i < d->nvqs; ++i) {
1472 mutex_lock(&d->vqs[i]->mutex);
1473 d->vqs[i]->umem = newumem;
1474 mutex_unlock(&d->vqs[i]->mutex);
1475 }
1476
1477 kvfree(newmem);
1478 vhost_umem_clean(oldumem);
1479 return 0;
1480
1481err:
1482 vhost_umem_clean(newumem);
1483 kvfree(newmem);
1484 return -EFAULT;
1485}
1486
1487static long vhost_vring_set_num(struct vhost_dev *d,
1488 struct vhost_virtqueue *vq,
1489 void __user *argp)
1490{
1491 struct vhost_vring_state s;
1492
1493 /* Resizing ring with an active backend?
1494 * You don't want to do that. */
1495 if (vq->private_data)
1496 return -EBUSY;
1497
1498 if (copy_from_user(&s, argp, sizeof s))
1499 return -EFAULT;
1500
1501 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
1502 return -EINVAL;
1503 vq->num = s.num;
1504
1505 return 0;
1506}
1507
1508static long vhost_vring_set_addr(struct vhost_dev *d,
1509 struct vhost_virtqueue *vq,
1510 void __user *argp)
1511{
1512 struct vhost_vring_addr a;
1513
1514 if (copy_from_user(&a, argp, sizeof a))
1515 return -EFAULT;
1516 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
1517 return -EOPNOTSUPP;
1518
1519 /* For 32bit, verify that the top 32bits of the user
1520 data are set to zero. */
1521 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1522 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1523 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
1524 return -EFAULT;
1525
1526 /* Make sure it's safe to cast pointers to vring types. */
1527 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1528 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1529 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1530 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1531 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
1532 return -EINVAL;
1533
1534 /* We only verify access here if backend is configured.
1535 * If it is not, we don't as size might not have been setup.
1536 * We will verify when backend is configured. */
1537 if (vq->private_data) {
1538 if (!vq_access_ok(vq, vq->num,
1539 (void __user *)(unsigned long)a.desc_user_addr,
1540 (void __user *)(unsigned long)a.avail_user_addr,
1541 (void __user *)(unsigned long)a.used_user_addr))
1542 return -EINVAL;
1543
1544 /* Also validate log access for used ring if enabled. */
1545 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1546 !log_access_ok(vq->log_base, a.log_guest_addr,
1547 sizeof *vq->used +
1548 vq->num * sizeof *vq->used->ring))
1549 return -EINVAL;
1550 }
1551
1552 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1553 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1554 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1555 vq->log_addr = a.log_guest_addr;
1556 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1557
1558 return 0;
1559}
1560
1561static long vhost_vring_set_num_addr(struct vhost_dev *d,
1562 struct vhost_virtqueue *vq,
1563 unsigned int ioctl,
1564 void __user *argp)
1565{
1566 long r;
1567
1568 mutex_lock(&vq->mutex);
1569
1570 switch (ioctl) {
1571 case VHOST_SET_VRING_NUM:
1572 r = vhost_vring_set_num(d, vq, argp);
1573 break;
1574 case VHOST_SET_VRING_ADDR:
1575 r = vhost_vring_set_addr(d, vq, argp);
1576 break;
1577 default:
1578 BUG();
1579 }
1580
1581 mutex_unlock(&vq->mutex);
1582
1583 return r;
1584}
1585long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1586{
1587 struct file *eventfp, *filep = NULL;
1588 bool pollstart = false, pollstop = false;
1589 struct eventfd_ctx *ctx = NULL;
1590 u32 __user *idxp = argp;
1591 struct vhost_virtqueue *vq;
1592 struct vhost_vring_state s;
1593 struct vhost_vring_file f;
1594 u32 idx;
1595 long r;
1596
1597 r = get_user(idx, idxp);
1598 if (r < 0)
1599 return r;
1600 if (idx >= d->nvqs)
1601 return -ENOBUFS;
1602
1603 idx = array_index_nospec(idx, d->nvqs);
1604 vq = d->vqs[idx];
1605
1606 if (ioctl == VHOST_SET_VRING_NUM ||
1607 ioctl == VHOST_SET_VRING_ADDR) {
1608 return vhost_vring_set_num_addr(d, vq, ioctl, argp);
1609 }
1610
1611 mutex_lock(&vq->mutex);
1612
1613 switch (ioctl) {
1614 case VHOST_SET_VRING_BASE:
1615 /* Moving base with an active backend?
1616 * You don't want to do that. */
1617 if (vq->private_data) {
1618 r = -EBUSY;
1619 break;
1620 }
1621 if (copy_from_user(&s, argp, sizeof s)) {
1622 r = -EFAULT;
1623 break;
1624 }
1625 if (s.num > 0xffff) {
1626 r = -EINVAL;
1627 break;
1628 }
1629 vq->last_avail_idx = s.num;
1630 /* Forget the cached index value. */
1631 vq->avail_idx = vq->last_avail_idx;
1632 break;
1633 case VHOST_GET_VRING_BASE:
1634 s.index = idx;
1635 s.num = vq->last_avail_idx;
1636 if (copy_to_user(argp, &s, sizeof s))
1637 r = -EFAULT;
1638 break;
1639 case VHOST_SET_VRING_KICK:
1640 if (copy_from_user(&f, argp, sizeof f)) {
1641 r = -EFAULT;
1642 break;
1643 }
1644 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1645 if (IS_ERR(eventfp)) {
1646 r = PTR_ERR(eventfp);
1647 break;
1648 }
1649 if (eventfp != vq->kick) {
1650 pollstop = (filep = vq->kick) != NULL;
1651 pollstart = (vq->kick = eventfp) != NULL;
1652 } else
1653 filep = eventfp;
1654 break;
1655 case VHOST_SET_VRING_CALL:
1656 if (copy_from_user(&f, argp, sizeof f)) {
1657 r = -EFAULT;
1658 break;
1659 }
1660 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1661 if (IS_ERR(ctx)) {
1662 r = PTR_ERR(ctx);
1663 break;
1664 }
1665 swap(ctx, vq->call_ctx);
1666 break;
1667 case VHOST_SET_VRING_ERR:
1668 if (copy_from_user(&f, argp, sizeof f)) {
1669 r = -EFAULT;
1670 break;
1671 }
1672 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1673 if (IS_ERR(ctx)) {
1674 r = PTR_ERR(ctx);
1675 break;
1676 }
1677 swap(ctx, vq->error_ctx);
1678 break;
1679 case VHOST_SET_VRING_ENDIAN:
1680 r = vhost_set_vring_endian(vq, argp);
1681 break;
1682 case VHOST_GET_VRING_ENDIAN:
1683 r = vhost_get_vring_endian(vq, idx, argp);
1684 break;
1685 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1686 if (copy_from_user(&s, argp, sizeof(s))) {
1687 r = -EFAULT;
1688 break;
1689 }
1690 vq->busyloop_timeout = s.num;
1691 break;
1692 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1693 s.index = idx;
1694 s.num = vq->busyloop_timeout;
1695 if (copy_to_user(argp, &s, sizeof(s)))
1696 r = -EFAULT;
1697 break;
1698 default:
1699 r = -ENOIOCTLCMD;
1700 }
1701
1702 if (pollstop && vq->handle_kick)
1703 vhost_poll_stop(&vq->poll);
1704
1705 if (!IS_ERR_OR_NULL(ctx))
1706 eventfd_ctx_put(ctx);
1707 if (filep)
1708 fput(filep);
1709
1710 if (pollstart && vq->handle_kick)
1711 r = vhost_poll_start(&vq->poll, vq->kick);
1712
1713 mutex_unlock(&vq->mutex);
1714
1715 if (pollstop && vq->handle_kick)
1716 vhost_poll_flush(&vq->poll);
1717 return r;
1718}
1719EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1720
1721int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1722{
1723 struct vhost_umem *niotlb, *oiotlb;
1724 int i;
1725
1726 niotlb = vhost_umem_alloc();
1727 if (!niotlb)
1728 return -ENOMEM;
1729
1730 oiotlb = d->iotlb;
1731 d->iotlb = niotlb;
1732
1733 for (i = 0; i < d->nvqs; ++i) {
1734 struct vhost_virtqueue *vq = d->vqs[i];
1735
1736 mutex_lock(&vq->mutex);
1737 vq->iotlb = niotlb;
1738 __vhost_vq_meta_reset(vq);
1739 mutex_unlock(&vq->mutex);
1740 }
1741
1742 vhost_umem_clean(oiotlb);
1743
1744 return 0;
1745}
1746EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1747
1748/* Caller must have device mutex */
1749long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1750{
1751 struct eventfd_ctx *ctx;
1752 u64 p;
1753 long r;
1754 int i, fd;
1755
1756 /* If you are not the owner, you can become one */
1757 if (ioctl == VHOST_SET_OWNER) {
1758 r = vhost_dev_set_owner(d);
1759 goto done;
1760 }
1761
1762 /* You must be the owner to do anything else */
1763 r = vhost_dev_check_owner(d);
1764 if (r)
1765 goto done;
1766
1767 switch (ioctl) {
1768 case VHOST_SET_MEM_TABLE:
1769 r = vhost_set_memory(d, argp);
1770 break;
1771 case VHOST_SET_LOG_BASE:
1772 if (copy_from_user(&p, argp, sizeof p)) {
1773 r = -EFAULT;
1774 break;
1775 }
1776 if ((u64)(unsigned long)p != p) {
1777 r = -EFAULT;
1778 break;
1779 }
1780 for (i = 0; i < d->nvqs; ++i) {
1781 struct vhost_virtqueue *vq;
1782 void __user *base = (void __user *)(unsigned long)p;
1783 vq = d->vqs[i];
1784 mutex_lock(&vq->mutex);
1785 /* If ring is inactive, will check when it's enabled. */
1786 if (vq->private_data && !vq_log_access_ok(vq, base))
1787 r = -EFAULT;
1788 else
1789 vq->log_base = base;
1790 mutex_unlock(&vq->mutex);
1791 }
1792 break;
1793 case VHOST_SET_LOG_FD:
1794 r = get_user(fd, (int __user *)argp);
1795 if (r < 0)
1796 break;
1797 ctx = fd == -1 ? NULL : eventfd_ctx_fdget(fd);
1798 if (IS_ERR(ctx)) {
1799 r = PTR_ERR(ctx);
1800 break;
1801 }
1802 swap(ctx, d->log_ctx);
1803 for (i = 0; i < d->nvqs; ++i) {
1804 mutex_lock(&d->vqs[i]->mutex);
1805 d->vqs[i]->log_ctx = d->log_ctx;
1806 mutex_unlock(&d->vqs[i]->mutex);
1807 }
1808 if (ctx)
1809 eventfd_ctx_put(ctx);
1810 break;
1811 default:
1812 r = -ENOIOCTLCMD;
1813 break;
1814 }
1815done:
1816 return r;
1817}
1818EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1819
1820/* TODO: This is really inefficient. We need something like get_user()
1821 * (instruction directly accesses the data, with an exception table entry
1822 * returning -EFAULT). See Documentation/x86/exception-tables.rst.
1823 */
1824static int set_bit_to_user(int nr, void __user *addr)
1825{
1826 unsigned long log = (unsigned long)addr;
1827 struct page *page;
1828 void *base;
1829 int bit = nr + (log % PAGE_SIZE) * 8;
1830 int r;
1831
1832 r = get_user_pages_fast(log, 1, FOLL_WRITE, &page);
1833 if (r < 0)
1834 return r;
1835 BUG_ON(r != 1);
1836 base = kmap_atomic(page);
1837 set_bit(bit, base);
1838 kunmap_atomic(base);
1839 set_page_dirty_lock(page);
1840 put_page(page);
1841 return 0;
1842}
1843
1844static int log_write(void __user *log_base,
1845 u64 write_address, u64 write_length)
1846{
1847 u64 write_page = write_address / VHOST_PAGE_SIZE;
1848 int r;
1849
1850 if (!write_length)
1851 return 0;
1852 write_length += write_address % VHOST_PAGE_SIZE;
1853 for (;;) {
1854 u64 base = (u64)(unsigned long)log_base;
1855 u64 log = base + write_page / 8;
1856 int bit = write_page % 8;
1857 if ((u64)(unsigned long)log != log)
1858 return -EFAULT;
1859 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1860 if (r < 0)
1861 return r;
1862 if (write_length <= VHOST_PAGE_SIZE)
1863 break;
1864 write_length -= VHOST_PAGE_SIZE;
1865 write_page += 1;
1866 }
1867 return r;
1868}
1869
1870static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
1871{
1872 struct vhost_umem *umem = vq->umem;
1873 struct vhost_umem_node *u;
1874 u64 start, end, l, min;
1875 int r;
1876 bool hit = false;
1877
1878 while (len) {
1879 min = len;
1880 /* More than one GPAs can be mapped into a single HVA. So
1881 * iterate all possible umems here to be safe.
1882 */
1883 list_for_each_entry(u, &umem->umem_list, link) {
1884 if (u->userspace_addr > hva - 1 + len ||
1885 u->userspace_addr - 1 + u->size < hva)
1886 continue;
1887 start = max(u->userspace_addr, hva);
1888 end = min(u->userspace_addr - 1 + u->size,
1889 hva - 1 + len);
1890 l = end - start + 1;
1891 r = log_write(vq->log_base,
1892 u->start + start - u->userspace_addr,
1893 l);
1894 if (r < 0)
1895 return r;
1896 hit = true;
1897 min = min(l, min);
1898 }
1899
1900 if (!hit)
1901 return -EFAULT;
1902
1903 len -= min;
1904 hva += min;
1905 }
1906
1907 return 0;
1908}
1909
1910static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
1911{
1912 struct iovec iov[64];
1913 int i, ret;
1914
1915 if (!vq->iotlb)
1916 return log_write(vq->log_base, vq->log_addr + used_offset, len);
1917
1918 ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
1919 len, iov, 64, VHOST_ACCESS_WO);
1920 if (ret < 0)
1921 return ret;
1922
1923 for (i = 0; i < ret; i++) {
1924 ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1925 iov[i].iov_len);
1926 if (ret)
1927 return ret;
1928 }
1929
1930 return 0;
1931}
1932
1933int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1934 unsigned int log_num, u64 len, struct iovec *iov, int count)
1935{
1936 int i, r;
1937
1938 /* Make sure data written is seen before log. */
1939 smp_wmb();
1940
1941 if (vq->iotlb) {
1942 for (i = 0; i < count; i++) {
1943 r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1944 iov[i].iov_len);
1945 if (r < 0)
1946 return r;
1947 }
1948 return 0;
1949 }
1950
1951 for (i = 0; i < log_num; ++i) {
1952 u64 l = min(log[i].len, len);
1953 r = log_write(vq->log_base, log[i].addr, l);
1954 if (r < 0)
1955 return r;
1956 len -= l;
1957 if (!len) {
1958 if (vq->log_ctx)
1959 eventfd_signal(vq->log_ctx, 1);
1960 return 0;
1961 }
1962 }
1963 /* Length written exceeds what we have stored. This is a bug. */
1964 BUG();
1965 return 0;
1966}
1967EXPORT_SYMBOL_GPL(vhost_log_write);
1968
1969static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1970{
1971 void __user *used;
1972 if (vhost_put_used_flags(vq))
1973 return -EFAULT;
1974 if (unlikely(vq->log_used)) {
1975 /* Make sure the flag is seen before log. */
1976 smp_wmb();
1977 /* Log used flag write. */
1978 used = &vq->used->flags;
1979 log_used(vq, (used - (void __user *)vq->used),
1980 sizeof vq->used->flags);
1981 if (vq->log_ctx)
1982 eventfd_signal(vq->log_ctx, 1);
1983 }
1984 return 0;
1985}
1986
1987static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1988{
1989 if (vhost_put_avail_event(vq))
1990 return -EFAULT;
1991 if (unlikely(vq->log_used)) {
1992 void __user *used;
1993 /* Make sure the event is seen before log. */
1994 smp_wmb();
1995 /* Log avail event write */
1996 used = vhost_avail_event(vq);
1997 log_used(vq, (used - (void __user *)vq->used),
1998 sizeof *vhost_avail_event(vq));
1999 if (vq->log_ctx)
2000 eventfd_signal(vq->log_ctx, 1);
2001 }
2002 return 0;
2003}
2004
2005int vhost_vq_init_access(struct vhost_virtqueue *vq)
2006{
2007 __virtio16 last_used_idx;
2008 int r;
2009 bool is_le = vq->is_le;
2010
2011 if (!vq->private_data)
2012 return 0;
2013
2014 vhost_init_is_le(vq);
2015
2016 r = vhost_update_used_flags(vq);
2017 if (r)
2018 goto err;
2019 vq->signalled_used_valid = false;
2020 if (!vq->iotlb &&
2021 !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
2022 r = -EFAULT;
2023 goto err;
2024 }
2025 r = vhost_get_used_idx(vq, &last_used_idx);
2026 if (r) {
2027 vq_err(vq, "Can't access used idx at %p\n",
2028 &vq->used->idx);
2029 goto err;
2030 }
2031 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
2032 return 0;
2033
2034err:
2035 vq->is_le = is_le;
2036 return r;
2037}
2038EXPORT_SYMBOL_GPL(vhost_vq_init_access);
2039
2040static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
2041 struct iovec iov[], int iov_size, int access)
2042{
2043 const struct vhost_umem_node *node;
2044 struct vhost_dev *dev = vq->dev;
2045 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
2046 struct iovec *_iov;
2047 u64 s = 0;
2048 int ret = 0;
2049
2050 while ((u64)len > s) {
2051 u64 size;
2052 if (unlikely(ret >= iov_size)) {
2053 ret = -ENOBUFS;
2054 break;
2055 }
2056
2057 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
2058 addr, addr + len - 1);
2059 if (node == NULL || node->start > addr) {
2060 if (umem != dev->iotlb) {
2061 ret = -EFAULT;
2062 break;
2063 }
2064 ret = -EAGAIN;
2065 break;
2066 } else if (!(node->perm & access)) {
2067 ret = -EPERM;
2068 break;
2069 }
2070
2071 _iov = iov + ret;
2072 size = node->size - addr + node->start;
2073 _iov->iov_len = min((u64)len - s, size);
2074 _iov->iov_base = (void __user *)(unsigned long)
2075 (node->userspace_addr + addr - node->start);
2076 s += size;
2077 addr += size;
2078 ++ret;
2079 }
2080
2081 if (ret == -EAGAIN)
2082 vhost_iotlb_miss(vq, addr, access);
2083 return ret;
2084}
2085
2086/* Each buffer in the virtqueues is actually a chain of descriptors. This
2087 * function returns the next descriptor in the chain,
2088 * or -1U if we're at the end. */
2089static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
2090{
2091 unsigned int next;
2092
2093 /* If this descriptor says it doesn't chain, we're done. */
2094 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
2095 return -1U;
2096
2097 /* Check they're not leading us off end of descriptors. */
2098 next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
2099 return next;
2100}
2101
2102static int get_indirect(struct vhost_virtqueue *vq,
2103 struct iovec iov[], unsigned int iov_size,
2104 unsigned int *out_num, unsigned int *in_num,
2105 struct vhost_log *log, unsigned int *log_num,
2106 struct vring_desc *indirect)
2107{
2108 struct vring_desc desc;
2109 unsigned int i = 0, count, found = 0;
2110 u32 len = vhost32_to_cpu(vq, indirect->len);
2111 struct iov_iter from;
2112 int ret, access;
2113
2114 /* Sanity check */
2115 if (unlikely(len % sizeof desc)) {
2116 vq_err(vq, "Invalid length in indirect descriptor: "
2117 "len 0x%llx not multiple of 0x%zx\n",
2118 (unsigned long long)len,
2119 sizeof desc);
2120 return -EINVAL;
2121 }
2122
2123 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
2124 UIO_MAXIOV, VHOST_ACCESS_RO);
2125 if (unlikely(ret < 0)) {
2126 if (ret != -EAGAIN)
2127 vq_err(vq, "Translation failure %d in indirect.\n", ret);
2128 return ret;
2129 }
2130 iov_iter_init(&from, READ, vq->indirect, ret, len);
2131
2132 /* We will use the result as an address to read from, so most
2133 * architectures only need a compiler barrier here. */
2134 read_barrier_depends();
2135
2136 count = len / sizeof desc;
2137 /* Buffers are chained via a 16 bit next field, so
2138 * we can have at most 2^16 of these. */
2139 if (unlikely(count > USHRT_MAX + 1)) {
2140 vq_err(vq, "Indirect buffer length too big: %d\n",
2141 indirect->len);
2142 return -E2BIG;
2143 }
2144
2145 do {
2146 unsigned iov_count = *in_num + *out_num;
2147 if (unlikely(++found > count)) {
2148 vq_err(vq, "Loop detected: last one at %u "
2149 "indirect size %u\n",
2150 i, count);
2151 return -EINVAL;
2152 }
2153 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
2154 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
2155 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2156 return -EINVAL;
2157 }
2158 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
2159 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
2160 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2161 return -EINVAL;
2162 }
2163
2164 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2165 access = VHOST_ACCESS_WO;
2166 else
2167 access = VHOST_ACCESS_RO;
2168
2169 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2170 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2171 iov_size - iov_count, access);
2172 if (unlikely(ret < 0)) {
2173 if (ret != -EAGAIN)
2174 vq_err(vq, "Translation failure %d indirect idx %d\n",
2175 ret, i);
2176 return ret;
2177 }
2178 /* If this is an input descriptor, increment that count. */
2179 if (access == VHOST_ACCESS_WO) {
2180 *in_num += ret;
2181 if (unlikely(log && ret)) {
2182 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2183 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2184 ++*log_num;
2185 }
2186 } else {
2187 /* If it's an output descriptor, they're all supposed
2188 * to come before any input descriptors. */
2189 if (unlikely(*in_num)) {
2190 vq_err(vq, "Indirect descriptor "
2191 "has out after in: idx %d\n", i);
2192 return -EINVAL;
2193 }
2194 *out_num += ret;
2195 }
2196 } while ((i = next_desc(vq, &desc)) != -1);
2197 return 0;
2198}
2199
2200/* This looks in the virtqueue and for the first available buffer, and converts
2201 * it to an iovec for convenient access. Since descriptors consist of some
2202 * number of output then some number of input descriptors, it's actually two
2203 * iovecs, but we pack them into one and note how many of each there were.
2204 *
2205 * This function returns the descriptor number found, or vq->num (which is
2206 * never a valid descriptor number) if none was found. A negative code is
2207 * returned on error. */
2208int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2209 struct iovec iov[], unsigned int iov_size,
2210 unsigned int *out_num, unsigned int *in_num,
2211 struct vhost_log *log, unsigned int *log_num)
2212{
2213 struct vring_desc desc;
2214 unsigned int i, head, found = 0;
2215 u16 last_avail_idx;
2216 __virtio16 avail_idx;
2217 __virtio16 ring_head;
2218 int ret, access;
2219
2220 /* Check it isn't doing very strange things with descriptor numbers. */
2221 last_avail_idx = vq->last_avail_idx;
2222
2223 if (vq->avail_idx == vq->last_avail_idx) {
2224 if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
2225 vq_err(vq, "Failed to access avail idx at %p\n",
2226 &vq->avail->idx);
2227 return -EFAULT;
2228 }
2229 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2230
2231 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2232 vq_err(vq, "Guest moved used index from %u to %u",
2233 last_avail_idx, vq->avail_idx);
2234 return -EFAULT;
2235 }
2236
2237 /* If there's nothing new since last we looked, return
2238 * invalid.
2239 */
2240 if (vq->avail_idx == last_avail_idx)
2241 return vq->num;
2242
2243 /* Only get avail ring entries after they have been
2244 * exposed by guest.
2245 */
2246 smp_rmb();
2247 }
2248
2249 /* Grab the next descriptor number they're advertising, and increment
2250 * the index we've seen. */
2251 if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
2252 vq_err(vq, "Failed to read head: idx %d address %p\n",
2253 last_avail_idx,
2254 &vq->avail->ring[last_avail_idx % vq->num]);
2255 return -EFAULT;
2256 }
2257
2258 head = vhost16_to_cpu(vq, ring_head);
2259
2260 /* If their number is silly, that's an error. */
2261 if (unlikely(head >= vq->num)) {
2262 vq_err(vq, "Guest says index %u > %u is available",
2263 head, vq->num);
2264 return -EINVAL;
2265 }
2266
2267 /* When we start there are none of either input nor output. */
2268 *out_num = *in_num = 0;
2269 if (unlikely(log))
2270 *log_num = 0;
2271
2272 i = head;
2273 do {
2274 unsigned iov_count = *in_num + *out_num;
2275 if (unlikely(i >= vq->num)) {
2276 vq_err(vq, "Desc index is %u > %u, head = %u",
2277 i, vq->num, head);
2278 return -EINVAL;
2279 }
2280 if (unlikely(++found > vq->num)) {
2281 vq_err(vq, "Loop detected: last one at %u "
2282 "vq size %u head %u\n",
2283 i, vq->num, head);
2284 return -EINVAL;
2285 }
2286 ret = vhost_get_desc(vq, &desc, i);
2287 if (unlikely(ret)) {
2288 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2289 i, vq->desc + i);
2290 return -EFAULT;
2291 }
2292 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2293 ret = get_indirect(vq, iov, iov_size,
2294 out_num, in_num,
2295 log, log_num, &desc);
2296 if (unlikely(ret < 0)) {
2297 if (ret != -EAGAIN)
2298 vq_err(vq, "Failure detected "
2299 "in indirect descriptor at idx %d\n", i);
2300 return ret;
2301 }
2302 continue;
2303 }
2304
2305 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2306 access = VHOST_ACCESS_WO;
2307 else
2308 access = VHOST_ACCESS_RO;
2309 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2310 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2311 iov_size - iov_count, access);
2312 if (unlikely(ret < 0)) {
2313 if (ret != -EAGAIN)
2314 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2315 ret, i);
2316 return ret;
2317 }
2318 if (access == VHOST_ACCESS_WO) {
2319 /* If this is an input descriptor,
2320 * increment that count. */
2321 *in_num += ret;
2322 if (unlikely(log && ret)) {
2323 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2324 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2325 ++*log_num;
2326 }
2327 } else {
2328 /* If it's an output descriptor, they're all supposed
2329 * to come before any input descriptors. */
2330 if (unlikely(*in_num)) {
2331 vq_err(vq, "Descriptor has out after in: "
2332 "idx %d\n", i);
2333 return -EINVAL;
2334 }
2335 *out_num += ret;
2336 }
2337 } while ((i = next_desc(vq, &desc)) != -1);
2338
2339 /* On success, increment avail index. */
2340 vq->last_avail_idx++;
2341
2342 /* Assume notifications from guest are disabled at this point,
2343 * if they aren't we would need to update avail_event index. */
2344 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2345 return head;
2346}
2347EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2348
2349/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2350void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2351{
2352 vq->last_avail_idx -= n;
2353}
2354EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2355
2356/* After we've used one of their buffers, we tell them about it. We'll then
2357 * want to notify the guest, using eventfd. */
2358int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2359{
2360 struct vring_used_elem heads = {
2361 cpu_to_vhost32(vq, head),
2362 cpu_to_vhost32(vq, len)
2363 };
2364
2365 return vhost_add_used_n(vq, &heads, 1);
2366}
2367EXPORT_SYMBOL_GPL(vhost_add_used);
2368
2369static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2370 struct vring_used_elem *heads,
2371 unsigned count)
2372{
2373 struct vring_used_elem __user *used;
2374 u16 old, new;
2375 int start;
2376
2377 start = vq->last_used_idx & (vq->num - 1);
2378 used = vq->used->ring + start;
2379 if (vhost_put_used(vq, heads, start, count)) {
2380 vq_err(vq, "Failed to write used");
2381 return -EFAULT;
2382 }
2383 if (unlikely(vq->log_used)) {
2384 /* Make sure data is seen before log. */
2385 smp_wmb();
2386 /* Log used ring entry write. */
2387 log_used(vq, ((void __user *)used - (void __user *)vq->used),
2388 count * sizeof *used);
2389 }
2390 old = vq->last_used_idx;
2391 new = (vq->last_used_idx += count);
2392 /* If the driver never bothers to signal in a very long while,
2393 * used index might wrap around. If that happens, invalidate
2394 * signalled_used index we stored. TODO: make sure driver
2395 * signals at least once in 2^16 and remove this. */
2396 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2397 vq->signalled_used_valid = false;
2398 return 0;
2399}
2400
2401/* After we've used one of their buffers, we tell them about it. We'll then
2402 * want to notify the guest, using eventfd. */
2403int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2404 unsigned count)
2405{
2406 int start, n, r;
2407
2408 start = vq->last_used_idx & (vq->num - 1);
2409 n = vq->num - start;
2410 if (n < count) {
2411 r = __vhost_add_used_n(vq, heads, n);
2412 if (r < 0)
2413 return r;
2414 heads += n;
2415 count -= n;
2416 }
2417 r = __vhost_add_used_n(vq, heads, count);
2418
2419 /* Make sure buffer is written before we update index. */
2420 smp_wmb();
2421 if (vhost_put_used_idx(vq)) {
2422 vq_err(vq, "Failed to increment used idx");
2423 return -EFAULT;
2424 }
2425 if (unlikely(vq->log_used)) {
2426 /* Make sure used idx is seen before log. */
2427 smp_wmb();
2428 /* Log used index update. */
2429 log_used(vq, offsetof(struct vring_used, idx),
2430 sizeof vq->used->idx);
2431 if (vq->log_ctx)
2432 eventfd_signal(vq->log_ctx, 1);
2433 }
2434 return r;
2435}
2436EXPORT_SYMBOL_GPL(vhost_add_used_n);
2437
2438static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2439{
2440 __u16 old, new;
2441 __virtio16 event;
2442 bool v;
2443 /* Flush out used index updates. This is paired
2444 * with the barrier that the Guest executes when enabling
2445 * interrupts. */
2446 smp_mb();
2447
2448 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2449 unlikely(vq->avail_idx == vq->last_avail_idx))
2450 return true;
2451
2452 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2453 __virtio16 flags;
2454 if (vhost_get_avail_flags(vq, &flags)) {
2455 vq_err(vq, "Failed to get flags");
2456 return true;
2457 }
2458 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2459 }
2460 old = vq->signalled_used;
2461 v = vq->signalled_used_valid;
2462 new = vq->signalled_used = vq->last_used_idx;
2463 vq->signalled_used_valid = true;
2464
2465 if (unlikely(!v))
2466 return true;
2467
2468 if (vhost_get_used_event(vq, &event)) {
2469 vq_err(vq, "Failed to get used event idx");
2470 return true;
2471 }
2472 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2473}
2474
2475/* This actually signals the guest, using eventfd. */
2476void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2477{
2478 /* Signal the Guest tell them we used something up. */
2479 if (vq->call_ctx && vhost_notify(dev, vq))
2480 eventfd_signal(vq->call_ctx, 1);
2481}
2482EXPORT_SYMBOL_GPL(vhost_signal);
2483
2484/* And here's the combo meal deal. Supersize me! */
2485void vhost_add_used_and_signal(struct vhost_dev *dev,
2486 struct vhost_virtqueue *vq,
2487 unsigned int head, int len)
2488{
2489 vhost_add_used(vq, head, len);
2490 vhost_signal(dev, vq);
2491}
2492EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2493
2494/* multi-buffer version of vhost_add_used_and_signal */
2495void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2496 struct vhost_virtqueue *vq,
2497 struct vring_used_elem *heads, unsigned count)
2498{
2499 vhost_add_used_n(vq, heads, count);
2500 vhost_signal(dev, vq);
2501}
2502EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2503
2504/* return true if we're sure that avaiable ring is empty */
2505bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2506{
2507 __virtio16 avail_idx;
2508 int r;
2509
2510 if (vq->avail_idx != vq->last_avail_idx)
2511 return false;
2512
2513 r = vhost_get_avail_idx(vq, &avail_idx);
2514 if (unlikely(r))
2515 return false;
2516 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2517
2518 return vq->avail_idx == vq->last_avail_idx;
2519}
2520EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2521
2522/* OK, now we need to know about added descriptors. */
2523bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2524{
2525 __virtio16 avail_idx;
2526 int r;
2527
2528 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2529 return false;
2530 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2531 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2532 r = vhost_update_used_flags(vq);
2533 if (r) {
2534 vq_err(vq, "Failed to enable notification at %p: %d\n",
2535 &vq->used->flags, r);
2536 return false;
2537 }
2538 } else {
2539 r = vhost_update_avail_event(vq, vq->avail_idx);
2540 if (r) {
2541 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2542 vhost_avail_event(vq), r);
2543 return false;
2544 }
2545 }
2546 /* They could have slipped one in as we were doing that: make
2547 * sure it's written, then check again. */
2548 smp_mb();
2549 r = vhost_get_avail_idx(vq, &avail_idx);
2550 if (r) {
2551 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2552 &vq->avail->idx, r);
2553 return false;
2554 }
2555
2556 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2557}
2558EXPORT_SYMBOL_GPL(vhost_enable_notify);
2559
2560/* We don't need to be notified again. */
2561void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2562{
2563 int r;
2564
2565 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2566 return;
2567 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2568 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2569 r = vhost_update_used_flags(vq);
2570 if (r)
2571 vq_err(vq, "Failed to enable notification at %p: %d\n",
2572 &vq->used->flags, r);
2573 }
2574}
2575EXPORT_SYMBOL_GPL(vhost_disable_notify);
2576
2577/* Create a new message. */
2578struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2579{
2580 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2581 if (!node)
2582 return NULL;
2583
2584 /* Make sure all padding within the structure is initialized. */
2585 memset(&node->msg, 0, sizeof node->msg);
2586 node->vq = vq;
2587 node->msg.type = type;
2588 return node;
2589}
2590EXPORT_SYMBOL_GPL(vhost_new_msg);
2591
2592void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2593 struct vhost_msg_node *node)
2594{
2595 spin_lock(&dev->iotlb_lock);
2596 list_add_tail(&node->node, head);
2597 spin_unlock(&dev->iotlb_lock);
2598
2599 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2600}
2601EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2602
2603struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2604 struct list_head *head)
2605{
2606 struct vhost_msg_node *node = NULL;
2607
2608 spin_lock(&dev->iotlb_lock);
2609 if (!list_empty(head)) {
2610 node = list_first_entry(head, struct vhost_msg_node,
2611 node);
2612 list_del(&node->node);
2613 }
2614 spin_unlock(&dev->iotlb_lock);
2615
2616 return node;
2617}
2618EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2619
2620
2621static int __init vhost_init(void)
2622{
2623 return 0;
2624}
2625
2626static void __exit vhost_exit(void)
2627{
2628}
2629
2630module_init(vhost_init);
2631module_exit(vhost_exit);
2632
2633MODULE_VERSION("0.0.1");
2634MODULE_LICENSE("GPL v2");
2635MODULE_AUTHOR("Michael S. Tsirkin");
2636MODULE_DESCRIPTION("Host kernel accelerator for virtio");