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Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6
[deliverable/linux.git] / drivers / vhost / vhost.c
1 /* Copyright (C) 2009 Red Hat, Inc.
2 * Copyright (C) 2006 Rusty Russell IBM Corporation
3 *
4 * Author: Michael S. Tsirkin <mst@redhat.com>
5 *
6 * Inspiration, some code, and most witty comments come from
7 * Documentation/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/miscdevice.h>
19 #include <linux/mutex.h>
20 #include <linux/rcupdate.h>
21 #include <linux/poll.h>
22 #include <linux/file.h>
23 #include <linux/highmem.h>
24 #include <linux/slab.h>
25 #include <linux/kthread.h>
26 #include <linux/cgroup.h>
27
28 #include <linux/net.h>
29 #include <linux/if_packet.h>
30 #include <linux/if_arp.h>
31
32 #include <net/sock.h>
33
34 #include "vhost.h"
35
36 enum {
37 VHOST_MEMORY_MAX_NREGIONS = 64,
38 VHOST_MEMORY_F_LOG = 0x1,
39 };
40
41 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
42 poll_table *pt)
43 {
44 struct vhost_poll *poll;
45 poll = container_of(pt, struct vhost_poll, table);
46
47 poll->wqh = wqh;
48 add_wait_queue(wqh, &poll->wait);
49 }
50
51 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
52 void *key)
53 {
54 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
55
56 if (!((unsigned long)key & poll->mask))
57 return 0;
58
59 vhost_poll_queue(poll);
60 return 0;
61 }
62
63 static void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
64 {
65 INIT_LIST_HEAD(&work->node);
66 work->fn = fn;
67 init_waitqueue_head(&work->done);
68 work->flushing = 0;
69 work->queue_seq = work->done_seq = 0;
70 }
71
72 /* Init poll structure */
73 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
74 unsigned long mask, struct vhost_dev *dev)
75 {
76 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
77 init_poll_funcptr(&poll->table, vhost_poll_func);
78 poll->mask = mask;
79 poll->dev = dev;
80
81 vhost_work_init(&poll->work, fn);
82 }
83
84 /* Start polling a file. We add ourselves to file's wait queue. The caller must
85 * keep a reference to a file until after vhost_poll_stop is called. */
86 void vhost_poll_start(struct vhost_poll *poll, struct file *file)
87 {
88 unsigned long mask;
89 mask = file->f_op->poll(file, &poll->table);
90 if (mask)
91 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
92 }
93
94 /* Stop polling a file. After this function returns, it becomes safe to drop the
95 * file reference. You must also flush afterwards. */
96 void vhost_poll_stop(struct vhost_poll *poll)
97 {
98 remove_wait_queue(poll->wqh, &poll->wait);
99 }
100
101 static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
102 {
103 unsigned seq;
104 int left;
105 int flushing;
106
107 spin_lock_irq(&dev->work_lock);
108 seq = work->queue_seq;
109 work->flushing++;
110 spin_unlock_irq(&dev->work_lock);
111 wait_event(work->done, ({
112 spin_lock_irq(&dev->work_lock);
113 left = seq - work->done_seq <= 0;
114 spin_unlock_irq(&dev->work_lock);
115 left;
116 }));
117 spin_lock_irq(&dev->work_lock);
118 flushing = --work->flushing;
119 spin_unlock_irq(&dev->work_lock);
120 BUG_ON(flushing < 0);
121 }
122
123 /* Flush any work that has been scheduled. When calling this, don't hold any
124 * locks that are also used by the callback. */
125 void vhost_poll_flush(struct vhost_poll *poll)
126 {
127 vhost_work_flush(poll->dev, &poll->work);
128 }
129
130 static inline void vhost_work_queue(struct vhost_dev *dev,
131 struct vhost_work *work)
132 {
133 unsigned long flags;
134
135 spin_lock_irqsave(&dev->work_lock, flags);
136 if (list_empty(&work->node)) {
137 list_add_tail(&work->node, &dev->work_list);
138 work->queue_seq++;
139 wake_up_process(dev->worker);
140 }
141 spin_unlock_irqrestore(&dev->work_lock, flags);
142 }
143
144 void vhost_poll_queue(struct vhost_poll *poll)
145 {
146 vhost_work_queue(poll->dev, &poll->work);
147 }
148
149 static void vhost_vq_reset(struct vhost_dev *dev,
150 struct vhost_virtqueue *vq)
151 {
152 vq->num = 1;
153 vq->desc = NULL;
154 vq->avail = NULL;
155 vq->used = NULL;
156 vq->last_avail_idx = 0;
157 vq->avail_idx = 0;
158 vq->last_used_idx = 0;
159 vq->used_flags = 0;
160 vq->used_flags = 0;
161 vq->log_used = false;
162 vq->log_addr = -1ull;
163 vq->vhost_hlen = 0;
164 vq->sock_hlen = 0;
165 vq->private_data = NULL;
166 vq->log_base = NULL;
167 vq->error_ctx = NULL;
168 vq->error = NULL;
169 vq->kick = NULL;
170 vq->call_ctx = NULL;
171 vq->call = NULL;
172 vq->log_ctx = NULL;
173 }
174
175 static int vhost_worker(void *data)
176 {
177 struct vhost_dev *dev = data;
178 struct vhost_work *work = NULL;
179 unsigned uninitialized_var(seq);
180
181 for (;;) {
182 /* mb paired w/ kthread_stop */
183 set_current_state(TASK_INTERRUPTIBLE);
184
185 spin_lock_irq(&dev->work_lock);
186 if (work) {
187 work->done_seq = seq;
188 if (work->flushing)
189 wake_up_all(&work->done);
190 }
191
192 if (kthread_should_stop()) {
193 spin_unlock_irq(&dev->work_lock);
194 __set_current_state(TASK_RUNNING);
195 return 0;
196 }
197 if (!list_empty(&dev->work_list)) {
198 work = list_first_entry(&dev->work_list,
199 struct vhost_work, node);
200 list_del_init(&work->node);
201 seq = work->queue_seq;
202 } else
203 work = NULL;
204 spin_unlock_irq(&dev->work_lock);
205
206 if (work) {
207 __set_current_state(TASK_RUNNING);
208 work->fn(work);
209 } else
210 schedule();
211
212 }
213 }
214
215 long vhost_dev_init(struct vhost_dev *dev,
216 struct vhost_virtqueue *vqs, int nvqs)
217 {
218 int i;
219
220 dev->vqs = vqs;
221 dev->nvqs = nvqs;
222 mutex_init(&dev->mutex);
223 dev->log_ctx = NULL;
224 dev->log_file = NULL;
225 dev->memory = NULL;
226 dev->mm = NULL;
227 spin_lock_init(&dev->work_lock);
228 INIT_LIST_HEAD(&dev->work_list);
229 dev->worker = NULL;
230
231 for (i = 0; i < dev->nvqs; ++i) {
232 dev->vqs[i].dev = dev;
233 mutex_init(&dev->vqs[i].mutex);
234 vhost_vq_reset(dev, dev->vqs + i);
235 if (dev->vqs[i].handle_kick)
236 vhost_poll_init(&dev->vqs[i].poll,
237 dev->vqs[i].handle_kick, POLLIN, dev);
238 }
239
240 return 0;
241 }
242
243 /* Caller should have device mutex */
244 long vhost_dev_check_owner(struct vhost_dev *dev)
245 {
246 /* Are you the owner? If not, I don't think you mean to do that */
247 return dev->mm == current->mm ? 0 : -EPERM;
248 }
249
250 struct vhost_attach_cgroups_struct {
251 struct vhost_work work;
252 struct task_struct *owner;
253 int ret;
254 };
255
256 static void vhost_attach_cgroups_work(struct vhost_work *work)
257 {
258 struct vhost_attach_cgroups_struct *s;
259 s = container_of(work, struct vhost_attach_cgroups_struct, work);
260 s->ret = cgroup_attach_task_all(s->owner, current);
261 }
262
263 static int vhost_attach_cgroups(struct vhost_dev *dev)
264 {
265 struct vhost_attach_cgroups_struct attach;
266 attach.owner = current;
267 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
268 vhost_work_queue(dev, &attach.work);
269 vhost_work_flush(dev, &attach.work);
270 return attach.ret;
271 }
272
273 /* Caller should have device mutex */
274 static long vhost_dev_set_owner(struct vhost_dev *dev)
275 {
276 struct task_struct *worker;
277 int err;
278 /* Is there an owner already? */
279 if (dev->mm) {
280 err = -EBUSY;
281 goto err_mm;
282 }
283 /* No owner, become one */
284 dev->mm = get_task_mm(current);
285 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
286 if (IS_ERR(worker)) {
287 err = PTR_ERR(worker);
288 goto err_worker;
289 }
290
291 dev->worker = worker;
292 wake_up_process(worker); /* avoid contributing to loadavg */
293
294 err = vhost_attach_cgroups(dev);
295 if (err)
296 goto err_cgroup;
297
298 return 0;
299 err_cgroup:
300 kthread_stop(worker);
301 dev->worker = NULL;
302 err_worker:
303 if (dev->mm)
304 mmput(dev->mm);
305 dev->mm = NULL;
306 err_mm:
307 return err;
308 }
309
310 /* Caller should have device mutex */
311 long vhost_dev_reset_owner(struct vhost_dev *dev)
312 {
313 struct vhost_memory *memory;
314
315 /* Restore memory to default empty mapping. */
316 memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
317 if (!memory)
318 return -ENOMEM;
319
320 vhost_dev_cleanup(dev);
321
322 memory->nregions = 0;
323 RCU_INIT_POINTER(dev->memory, memory);
324 return 0;
325 }
326
327 /* Caller should have device mutex */
328 void vhost_dev_cleanup(struct vhost_dev *dev)
329 {
330 int i;
331 for (i = 0; i < dev->nvqs; ++i) {
332 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) {
333 vhost_poll_stop(&dev->vqs[i].poll);
334 vhost_poll_flush(&dev->vqs[i].poll);
335 }
336 if (dev->vqs[i].error_ctx)
337 eventfd_ctx_put(dev->vqs[i].error_ctx);
338 if (dev->vqs[i].error)
339 fput(dev->vqs[i].error);
340 if (dev->vqs[i].kick)
341 fput(dev->vqs[i].kick);
342 if (dev->vqs[i].call_ctx)
343 eventfd_ctx_put(dev->vqs[i].call_ctx);
344 if (dev->vqs[i].call)
345 fput(dev->vqs[i].call);
346 vhost_vq_reset(dev, dev->vqs + i);
347 }
348 if (dev->log_ctx)
349 eventfd_ctx_put(dev->log_ctx);
350 dev->log_ctx = NULL;
351 if (dev->log_file)
352 fput(dev->log_file);
353 dev->log_file = NULL;
354 /* No one will access memory at this point */
355 kfree(rcu_dereference_protected(dev->memory,
356 lockdep_is_held(&dev->mutex)));
357 RCU_INIT_POINTER(dev->memory, NULL);
358 if (dev->mm)
359 mmput(dev->mm);
360 dev->mm = NULL;
361
362 WARN_ON(!list_empty(&dev->work_list));
363 if (dev->worker) {
364 kthread_stop(dev->worker);
365 dev->worker = NULL;
366 }
367 }
368
369 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
370 {
371 u64 a = addr / VHOST_PAGE_SIZE / 8;
372 /* Make sure 64 bit math will not overflow. */
373 if (a > ULONG_MAX - (unsigned long)log_base ||
374 a + (unsigned long)log_base > ULONG_MAX)
375 return -EFAULT;
376
377 return access_ok(VERIFY_WRITE, log_base + a,
378 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
379 }
380
381 /* Caller should have vq mutex and device mutex. */
382 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
383 int log_all)
384 {
385 int i;
386
387 if (!mem)
388 return 0;
389
390 for (i = 0; i < mem->nregions; ++i) {
391 struct vhost_memory_region *m = mem->regions + i;
392 unsigned long a = m->userspace_addr;
393 if (m->memory_size > ULONG_MAX)
394 return 0;
395 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
396 m->memory_size))
397 return 0;
398 else if (log_all && !log_access_ok(log_base,
399 m->guest_phys_addr,
400 m->memory_size))
401 return 0;
402 }
403 return 1;
404 }
405
406 /* Can we switch to this memory table? */
407 /* Caller should have device mutex but not vq mutex */
408 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
409 int log_all)
410 {
411 int i;
412 for (i = 0; i < d->nvqs; ++i) {
413 int ok;
414 mutex_lock(&d->vqs[i].mutex);
415 /* If ring is inactive, will check when it's enabled. */
416 if (d->vqs[i].private_data)
417 ok = vq_memory_access_ok(d->vqs[i].log_base, mem,
418 log_all);
419 else
420 ok = 1;
421 mutex_unlock(&d->vqs[i].mutex);
422 if (!ok)
423 return 0;
424 }
425 return 1;
426 }
427
428 static int vq_access_ok(unsigned int num,
429 struct vring_desc __user *desc,
430 struct vring_avail __user *avail,
431 struct vring_used __user *used)
432 {
433 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
434 access_ok(VERIFY_READ, avail,
435 sizeof *avail + num * sizeof *avail->ring) &&
436 access_ok(VERIFY_WRITE, used,
437 sizeof *used + num * sizeof *used->ring);
438 }
439
440 /* Can we log writes? */
441 /* Caller should have device mutex but not vq mutex */
442 int vhost_log_access_ok(struct vhost_dev *dev)
443 {
444 struct vhost_memory *mp;
445
446 mp = rcu_dereference_protected(dev->memory,
447 lockdep_is_held(&dev->mutex));
448 return memory_access_ok(dev, mp, 1);
449 }
450
451 /* Verify access for write logging. */
452 /* Caller should have vq mutex and device mutex */
453 static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base)
454 {
455 struct vhost_memory *mp;
456
457 mp = rcu_dereference_protected(vq->dev->memory,
458 lockdep_is_held(&vq->mutex));
459 return vq_memory_access_ok(log_base, mp,
460 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
461 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
462 sizeof *vq->used +
463 vq->num * sizeof *vq->used->ring));
464 }
465
466 /* Can we start vq? */
467 /* Caller should have vq mutex and device mutex */
468 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
469 {
470 return vq_access_ok(vq->num, vq->desc, vq->avail, vq->used) &&
471 vq_log_access_ok(vq, vq->log_base);
472 }
473
474 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
475 {
476 struct vhost_memory mem, *newmem, *oldmem;
477 unsigned long size = offsetof(struct vhost_memory, regions);
478 if (copy_from_user(&mem, m, size))
479 return -EFAULT;
480 if (mem.padding)
481 return -EOPNOTSUPP;
482 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
483 return -E2BIG;
484 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL);
485 if (!newmem)
486 return -ENOMEM;
487
488 memcpy(newmem, &mem, size);
489 if (copy_from_user(newmem->regions, m->regions,
490 mem.nregions * sizeof *m->regions)) {
491 kfree(newmem);
492 return -EFAULT;
493 }
494
495 if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL))) {
496 kfree(newmem);
497 return -EFAULT;
498 }
499 oldmem = rcu_dereference_protected(d->memory,
500 lockdep_is_held(&d->mutex));
501 rcu_assign_pointer(d->memory, newmem);
502 synchronize_rcu();
503 kfree(oldmem);
504 return 0;
505 }
506
507 static int init_used(struct vhost_virtqueue *vq,
508 struct vring_used __user *used)
509 {
510 int r = put_user(vq->used_flags, &used->flags);
511 if (r)
512 return r;
513 return get_user(vq->last_used_idx, &used->idx);
514 }
515
516 static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
517 {
518 struct file *eventfp, *filep = NULL,
519 *pollstart = NULL, *pollstop = NULL;
520 struct eventfd_ctx *ctx = NULL;
521 u32 __user *idxp = argp;
522 struct vhost_virtqueue *vq;
523 struct vhost_vring_state s;
524 struct vhost_vring_file f;
525 struct vhost_vring_addr a;
526 u32 idx;
527 long r;
528
529 r = get_user(idx, idxp);
530 if (r < 0)
531 return r;
532 if (idx >= d->nvqs)
533 return -ENOBUFS;
534
535 vq = d->vqs + idx;
536
537 mutex_lock(&vq->mutex);
538
539 switch (ioctl) {
540 case VHOST_SET_VRING_NUM:
541 /* Resizing ring with an active backend?
542 * You don't want to do that. */
543 if (vq->private_data) {
544 r = -EBUSY;
545 break;
546 }
547 if (copy_from_user(&s, argp, sizeof s)) {
548 r = -EFAULT;
549 break;
550 }
551 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
552 r = -EINVAL;
553 break;
554 }
555 vq->num = s.num;
556 break;
557 case VHOST_SET_VRING_BASE:
558 /* Moving base with an active backend?
559 * You don't want to do that. */
560 if (vq->private_data) {
561 r = -EBUSY;
562 break;
563 }
564 if (copy_from_user(&s, argp, sizeof s)) {
565 r = -EFAULT;
566 break;
567 }
568 if (s.num > 0xffff) {
569 r = -EINVAL;
570 break;
571 }
572 vq->last_avail_idx = s.num;
573 /* Forget the cached index value. */
574 vq->avail_idx = vq->last_avail_idx;
575 break;
576 case VHOST_GET_VRING_BASE:
577 s.index = idx;
578 s.num = vq->last_avail_idx;
579 if (copy_to_user(argp, &s, sizeof s))
580 r = -EFAULT;
581 break;
582 case VHOST_SET_VRING_ADDR:
583 if (copy_from_user(&a, argp, sizeof a)) {
584 r = -EFAULT;
585 break;
586 }
587 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
588 r = -EOPNOTSUPP;
589 break;
590 }
591 /* For 32bit, verify that the top 32bits of the user
592 data are set to zero. */
593 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
594 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
595 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
596 r = -EFAULT;
597 break;
598 }
599 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
600 (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
601 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
602 r = -EINVAL;
603 break;
604 }
605
606 /* We only verify access here if backend is configured.
607 * If it is not, we don't as size might not have been setup.
608 * We will verify when backend is configured. */
609 if (vq->private_data) {
610 if (!vq_access_ok(vq->num,
611 (void __user *)(unsigned long)a.desc_user_addr,
612 (void __user *)(unsigned long)a.avail_user_addr,
613 (void __user *)(unsigned long)a.used_user_addr)) {
614 r = -EINVAL;
615 break;
616 }
617
618 /* Also validate log access for used ring if enabled. */
619 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
620 !log_access_ok(vq->log_base, a.log_guest_addr,
621 sizeof *vq->used +
622 vq->num * sizeof *vq->used->ring)) {
623 r = -EINVAL;
624 break;
625 }
626 }
627
628 r = init_used(vq, (struct vring_used __user *)(unsigned long)
629 a.used_user_addr);
630 if (r)
631 break;
632 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
633 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
634 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
635 vq->log_addr = a.log_guest_addr;
636 vq->used = (void __user *)(unsigned long)a.used_user_addr;
637 break;
638 case VHOST_SET_VRING_KICK:
639 if (copy_from_user(&f, argp, sizeof f)) {
640 r = -EFAULT;
641 break;
642 }
643 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
644 if (IS_ERR(eventfp)) {
645 r = PTR_ERR(eventfp);
646 break;
647 }
648 if (eventfp != vq->kick) {
649 pollstop = filep = vq->kick;
650 pollstart = vq->kick = eventfp;
651 } else
652 filep = eventfp;
653 break;
654 case VHOST_SET_VRING_CALL:
655 if (copy_from_user(&f, argp, sizeof f)) {
656 r = -EFAULT;
657 break;
658 }
659 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
660 if (IS_ERR(eventfp)) {
661 r = PTR_ERR(eventfp);
662 break;
663 }
664 if (eventfp != vq->call) {
665 filep = vq->call;
666 ctx = vq->call_ctx;
667 vq->call = eventfp;
668 vq->call_ctx = eventfp ?
669 eventfd_ctx_fileget(eventfp) : NULL;
670 } else
671 filep = eventfp;
672 break;
673 case VHOST_SET_VRING_ERR:
674 if (copy_from_user(&f, argp, sizeof f)) {
675 r = -EFAULT;
676 break;
677 }
678 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
679 if (IS_ERR(eventfp)) {
680 r = PTR_ERR(eventfp);
681 break;
682 }
683 if (eventfp != vq->error) {
684 filep = vq->error;
685 vq->error = eventfp;
686 ctx = vq->error_ctx;
687 vq->error_ctx = eventfp ?
688 eventfd_ctx_fileget(eventfp) : NULL;
689 } else
690 filep = eventfp;
691 break;
692 default:
693 r = -ENOIOCTLCMD;
694 }
695
696 if (pollstop && vq->handle_kick)
697 vhost_poll_stop(&vq->poll);
698
699 if (ctx)
700 eventfd_ctx_put(ctx);
701 if (filep)
702 fput(filep);
703
704 if (pollstart && vq->handle_kick)
705 vhost_poll_start(&vq->poll, vq->kick);
706
707 mutex_unlock(&vq->mutex);
708
709 if (pollstop && vq->handle_kick)
710 vhost_poll_flush(&vq->poll);
711 return r;
712 }
713
714 /* Caller must have device mutex */
715 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
716 {
717 void __user *argp = (void __user *)arg;
718 struct file *eventfp, *filep = NULL;
719 struct eventfd_ctx *ctx = NULL;
720 u64 p;
721 long r;
722 int i, fd;
723
724 /* If you are not the owner, you can become one */
725 if (ioctl == VHOST_SET_OWNER) {
726 r = vhost_dev_set_owner(d);
727 goto done;
728 }
729
730 /* You must be the owner to do anything else */
731 r = vhost_dev_check_owner(d);
732 if (r)
733 goto done;
734
735 switch (ioctl) {
736 case VHOST_SET_MEM_TABLE:
737 r = vhost_set_memory(d, argp);
738 break;
739 case VHOST_SET_LOG_BASE:
740 if (copy_from_user(&p, argp, sizeof p)) {
741 r = -EFAULT;
742 break;
743 }
744 if ((u64)(unsigned long)p != p) {
745 r = -EFAULT;
746 break;
747 }
748 for (i = 0; i < d->nvqs; ++i) {
749 struct vhost_virtqueue *vq;
750 void __user *base = (void __user *)(unsigned long)p;
751 vq = d->vqs + i;
752 mutex_lock(&vq->mutex);
753 /* If ring is inactive, will check when it's enabled. */
754 if (vq->private_data && !vq_log_access_ok(vq, base))
755 r = -EFAULT;
756 else
757 vq->log_base = base;
758 mutex_unlock(&vq->mutex);
759 }
760 break;
761 case VHOST_SET_LOG_FD:
762 r = get_user(fd, (int __user *)argp);
763 if (r < 0)
764 break;
765 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
766 if (IS_ERR(eventfp)) {
767 r = PTR_ERR(eventfp);
768 break;
769 }
770 if (eventfp != d->log_file) {
771 filep = d->log_file;
772 ctx = d->log_ctx;
773 d->log_ctx = eventfp ?
774 eventfd_ctx_fileget(eventfp) : NULL;
775 } else
776 filep = eventfp;
777 for (i = 0; i < d->nvqs; ++i) {
778 mutex_lock(&d->vqs[i].mutex);
779 d->vqs[i].log_ctx = d->log_ctx;
780 mutex_unlock(&d->vqs[i].mutex);
781 }
782 if (ctx)
783 eventfd_ctx_put(ctx);
784 if (filep)
785 fput(filep);
786 break;
787 default:
788 r = vhost_set_vring(d, ioctl, argp);
789 break;
790 }
791 done:
792 return r;
793 }
794
795 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
796 __u64 addr, __u32 len)
797 {
798 struct vhost_memory_region *reg;
799 int i;
800 /* linear search is not brilliant, but we really have on the order of 6
801 * regions in practice */
802 for (i = 0; i < mem->nregions; ++i) {
803 reg = mem->regions + i;
804 if (reg->guest_phys_addr <= addr &&
805 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
806 return reg;
807 }
808 return NULL;
809 }
810
811 /* TODO: This is really inefficient. We need something like get_user()
812 * (instruction directly accesses the data, with an exception table entry
813 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
814 */
815 static int set_bit_to_user(int nr, void __user *addr)
816 {
817 unsigned long log = (unsigned long)addr;
818 struct page *page;
819 void *base;
820 int bit = nr + (log % PAGE_SIZE) * 8;
821 int r;
822 r = get_user_pages_fast(log, 1, 1, &page);
823 if (r < 0)
824 return r;
825 BUG_ON(r != 1);
826 base = kmap_atomic(page, KM_USER0);
827 set_bit(bit, base);
828 kunmap_atomic(base, KM_USER0);
829 set_page_dirty_lock(page);
830 put_page(page);
831 return 0;
832 }
833
834 static int log_write(void __user *log_base,
835 u64 write_address, u64 write_length)
836 {
837 int r;
838 if (!write_length)
839 return 0;
840 write_address /= VHOST_PAGE_SIZE;
841 for (;;) {
842 u64 base = (u64)(unsigned long)log_base;
843 u64 log = base + write_address / 8;
844 int bit = write_address % 8;
845 if ((u64)(unsigned long)log != log)
846 return -EFAULT;
847 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
848 if (r < 0)
849 return r;
850 if (write_length <= VHOST_PAGE_SIZE)
851 break;
852 write_length -= VHOST_PAGE_SIZE;
853 write_address += VHOST_PAGE_SIZE;
854 }
855 return r;
856 }
857
858 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
859 unsigned int log_num, u64 len)
860 {
861 int i, r;
862
863 /* Make sure data written is seen before log. */
864 smp_wmb();
865 for (i = 0; i < log_num; ++i) {
866 u64 l = min(log[i].len, len);
867 r = log_write(vq->log_base, log[i].addr, l);
868 if (r < 0)
869 return r;
870 len -= l;
871 if (!len) {
872 if (vq->log_ctx)
873 eventfd_signal(vq->log_ctx, 1);
874 return 0;
875 }
876 }
877 /* Length written exceeds what we have stored. This is a bug. */
878 BUG();
879 return 0;
880 }
881
882 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
883 struct iovec iov[], int iov_size)
884 {
885 const struct vhost_memory_region *reg;
886 struct vhost_memory *mem;
887 struct iovec *_iov;
888 u64 s = 0;
889 int ret = 0;
890
891 rcu_read_lock();
892
893 mem = rcu_dereference(dev->memory);
894 while ((u64)len > s) {
895 u64 size;
896 if (unlikely(ret >= iov_size)) {
897 ret = -ENOBUFS;
898 break;
899 }
900 reg = find_region(mem, addr, len);
901 if (unlikely(!reg)) {
902 ret = -EFAULT;
903 break;
904 }
905 _iov = iov + ret;
906 size = reg->memory_size - addr + reg->guest_phys_addr;
907 _iov->iov_len = min((u64)len, size);
908 _iov->iov_base = (void __user *)(unsigned long)
909 (reg->userspace_addr + addr - reg->guest_phys_addr);
910 s += size;
911 addr += size;
912 ++ret;
913 }
914
915 rcu_read_unlock();
916 return ret;
917 }
918
919 /* Each buffer in the virtqueues is actually a chain of descriptors. This
920 * function returns the next descriptor in the chain,
921 * or -1U if we're at the end. */
922 static unsigned next_desc(struct vring_desc *desc)
923 {
924 unsigned int next;
925
926 /* If this descriptor says it doesn't chain, we're done. */
927 if (!(desc->flags & VRING_DESC_F_NEXT))
928 return -1U;
929
930 /* Check they're not leading us off end of descriptors. */
931 next = desc->next;
932 /* Make sure compiler knows to grab that: we don't want it changing! */
933 /* We will use the result as an index in an array, so most
934 * architectures only need a compiler barrier here. */
935 read_barrier_depends();
936
937 return next;
938 }
939
940 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
941 struct iovec iov[], unsigned int iov_size,
942 unsigned int *out_num, unsigned int *in_num,
943 struct vhost_log *log, unsigned int *log_num,
944 struct vring_desc *indirect)
945 {
946 struct vring_desc desc;
947 unsigned int i = 0, count, found = 0;
948 int ret;
949
950 /* Sanity check */
951 if (unlikely(indirect->len % sizeof desc)) {
952 vq_err(vq, "Invalid length in indirect descriptor: "
953 "len 0x%llx not multiple of 0x%zx\n",
954 (unsigned long long)indirect->len,
955 sizeof desc);
956 return -EINVAL;
957 }
958
959 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect,
960 ARRAY_SIZE(vq->indirect));
961 if (unlikely(ret < 0)) {
962 vq_err(vq, "Translation failure %d in indirect.\n", ret);
963 return ret;
964 }
965
966 /* We will use the result as an address to read from, so most
967 * architectures only need a compiler barrier here. */
968 read_barrier_depends();
969
970 count = indirect->len / sizeof desc;
971 /* Buffers are chained via a 16 bit next field, so
972 * we can have at most 2^16 of these. */
973 if (unlikely(count > USHRT_MAX + 1)) {
974 vq_err(vq, "Indirect buffer length too big: %d\n",
975 indirect->len);
976 return -E2BIG;
977 }
978
979 do {
980 unsigned iov_count = *in_num + *out_num;
981 if (unlikely(++found > count)) {
982 vq_err(vq, "Loop detected: last one at %u "
983 "indirect size %u\n",
984 i, count);
985 return -EINVAL;
986 }
987 if (unlikely(memcpy_fromiovec((unsigned char *)&desc, vq->indirect,
988 sizeof desc))) {
989 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
990 i, (size_t)indirect->addr + i * sizeof desc);
991 return -EINVAL;
992 }
993 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
994 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
995 i, (size_t)indirect->addr + i * sizeof desc);
996 return -EINVAL;
997 }
998
999 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1000 iov_size - iov_count);
1001 if (unlikely(ret < 0)) {
1002 vq_err(vq, "Translation failure %d indirect idx %d\n",
1003 ret, i);
1004 return ret;
1005 }
1006 /* If this is an input descriptor, increment that count. */
1007 if (desc.flags & VRING_DESC_F_WRITE) {
1008 *in_num += ret;
1009 if (unlikely(log)) {
1010 log[*log_num].addr = desc.addr;
1011 log[*log_num].len = desc.len;
1012 ++*log_num;
1013 }
1014 } else {
1015 /* If it's an output descriptor, they're all supposed
1016 * to come before any input descriptors. */
1017 if (unlikely(*in_num)) {
1018 vq_err(vq, "Indirect descriptor "
1019 "has out after in: idx %d\n", i);
1020 return -EINVAL;
1021 }
1022 *out_num += ret;
1023 }
1024 } while ((i = next_desc(&desc)) != -1);
1025 return 0;
1026 }
1027
1028 /* This looks in the virtqueue and for the first available buffer, and converts
1029 * it to an iovec for convenient access. Since descriptors consist of some
1030 * number of output then some number of input descriptors, it's actually two
1031 * iovecs, but we pack them into one and note how many of each there were.
1032 *
1033 * This function returns the descriptor number found, or vq->num (which is
1034 * never a valid descriptor number) if none was found. A negative code is
1035 * returned on error. */
1036 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1037 struct iovec iov[], unsigned int iov_size,
1038 unsigned int *out_num, unsigned int *in_num,
1039 struct vhost_log *log, unsigned int *log_num)
1040 {
1041 struct vring_desc desc;
1042 unsigned int i, head, found = 0;
1043 u16 last_avail_idx;
1044 int ret;
1045
1046 /* Check it isn't doing very strange things with descriptor numbers. */
1047 last_avail_idx = vq->last_avail_idx;
1048 if (unlikely(get_user(vq->avail_idx, &vq->avail->idx))) {
1049 vq_err(vq, "Failed to access avail idx at %p\n",
1050 &vq->avail->idx);
1051 return -EFAULT;
1052 }
1053
1054 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1055 vq_err(vq, "Guest moved used index from %u to %u",
1056 last_avail_idx, vq->avail_idx);
1057 return -EFAULT;
1058 }
1059
1060 /* If there's nothing new since last we looked, return invalid. */
1061 if (vq->avail_idx == last_avail_idx)
1062 return vq->num;
1063
1064 /* Only get avail ring entries after they have been exposed by guest. */
1065 smp_rmb();
1066
1067 /* Grab the next descriptor number they're advertising, and increment
1068 * the index we've seen. */
1069 if (unlikely(get_user(head,
1070 &vq->avail->ring[last_avail_idx % vq->num]))) {
1071 vq_err(vq, "Failed to read head: idx %d address %p\n",
1072 last_avail_idx,
1073 &vq->avail->ring[last_avail_idx % vq->num]);
1074 return -EFAULT;
1075 }
1076
1077 /* If their number is silly, that's an error. */
1078 if (unlikely(head >= vq->num)) {
1079 vq_err(vq, "Guest says index %u > %u is available",
1080 head, vq->num);
1081 return -EINVAL;
1082 }
1083
1084 /* When we start there are none of either input nor output. */
1085 *out_num = *in_num = 0;
1086 if (unlikely(log))
1087 *log_num = 0;
1088
1089 i = head;
1090 do {
1091 unsigned iov_count = *in_num + *out_num;
1092 if (unlikely(i >= vq->num)) {
1093 vq_err(vq, "Desc index is %u > %u, head = %u",
1094 i, vq->num, head);
1095 return -EINVAL;
1096 }
1097 if (unlikely(++found > vq->num)) {
1098 vq_err(vq, "Loop detected: last one at %u "
1099 "vq size %u head %u\n",
1100 i, vq->num, head);
1101 return -EINVAL;
1102 }
1103 ret = copy_from_user(&desc, vq->desc + i, sizeof desc);
1104 if (unlikely(ret)) {
1105 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1106 i, vq->desc + i);
1107 return -EFAULT;
1108 }
1109 if (desc.flags & VRING_DESC_F_INDIRECT) {
1110 ret = get_indirect(dev, vq, iov, iov_size,
1111 out_num, in_num,
1112 log, log_num, &desc);
1113 if (unlikely(ret < 0)) {
1114 vq_err(vq, "Failure detected "
1115 "in indirect descriptor at idx %d\n", i);
1116 return ret;
1117 }
1118 continue;
1119 }
1120
1121 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1122 iov_size - iov_count);
1123 if (unlikely(ret < 0)) {
1124 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1125 ret, i);
1126 return ret;
1127 }
1128 if (desc.flags & VRING_DESC_F_WRITE) {
1129 /* If this is an input descriptor,
1130 * increment that count. */
1131 *in_num += ret;
1132 if (unlikely(log)) {
1133 log[*log_num].addr = desc.addr;
1134 log[*log_num].len = desc.len;
1135 ++*log_num;
1136 }
1137 } else {
1138 /* If it's an output descriptor, they're all supposed
1139 * to come before any input descriptors. */
1140 if (unlikely(*in_num)) {
1141 vq_err(vq, "Descriptor has out after in: "
1142 "idx %d\n", i);
1143 return -EINVAL;
1144 }
1145 *out_num += ret;
1146 }
1147 } while ((i = next_desc(&desc)) != -1);
1148
1149 /* On success, increment avail index. */
1150 vq->last_avail_idx++;
1151 return head;
1152 }
1153
1154 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1155 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1156 {
1157 vq->last_avail_idx -= n;
1158 }
1159
1160 /* After we've used one of their buffers, we tell them about it. We'll then
1161 * want to notify the guest, using eventfd. */
1162 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1163 {
1164 struct vring_used_elem __user *used;
1165
1166 /* The virtqueue contains a ring of used buffers. Get a pointer to the
1167 * next entry in that used ring. */
1168 used = &vq->used->ring[vq->last_used_idx % vq->num];
1169 if (put_user(head, &used->id)) {
1170 vq_err(vq, "Failed to write used id");
1171 return -EFAULT;
1172 }
1173 if (put_user(len, &used->len)) {
1174 vq_err(vq, "Failed to write used len");
1175 return -EFAULT;
1176 }
1177 /* Make sure buffer is written before we update index. */
1178 smp_wmb();
1179 if (put_user(vq->last_used_idx + 1, &vq->used->idx)) {
1180 vq_err(vq, "Failed to increment used idx");
1181 return -EFAULT;
1182 }
1183 if (unlikely(vq->log_used)) {
1184 /* Make sure data is seen before log. */
1185 smp_wmb();
1186 /* Log used ring entry write. */
1187 log_write(vq->log_base,
1188 vq->log_addr +
1189 ((void __user *)used - (void __user *)vq->used),
1190 sizeof *used);
1191 /* Log used index update. */
1192 log_write(vq->log_base,
1193 vq->log_addr + offsetof(struct vring_used, idx),
1194 sizeof vq->used->idx);
1195 if (vq->log_ctx)
1196 eventfd_signal(vq->log_ctx, 1);
1197 }
1198 vq->last_used_idx++;
1199 return 0;
1200 }
1201
1202 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1203 struct vring_used_elem *heads,
1204 unsigned count)
1205 {
1206 struct vring_used_elem __user *used;
1207 int start;
1208
1209 start = vq->last_used_idx % vq->num;
1210 used = vq->used->ring + start;
1211 if (copy_to_user(used, heads, count * sizeof *used)) {
1212 vq_err(vq, "Failed to write used");
1213 return -EFAULT;
1214 }
1215 if (unlikely(vq->log_used)) {
1216 /* Make sure data is seen before log. */
1217 smp_wmb();
1218 /* Log used ring entry write. */
1219 log_write(vq->log_base,
1220 vq->log_addr +
1221 ((void __user *)used - (void __user *)vq->used),
1222 count * sizeof *used);
1223 }
1224 vq->last_used_idx += count;
1225 return 0;
1226 }
1227
1228 /* After we've used one of their buffers, we tell them about it. We'll then
1229 * want to notify the guest, using eventfd. */
1230 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1231 unsigned count)
1232 {
1233 int start, n, r;
1234
1235 start = vq->last_used_idx % vq->num;
1236 n = vq->num - start;
1237 if (n < count) {
1238 r = __vhost_add_used_n(vq, heads, n);
1239 if (r < 0)
1240 return r;
1241 heads += n;
1242 count -= n;
1243 }
1244 r = __vhost_add_used_n(vq, heads, count);
1245
1246 /* Make sure buffer is written before we update index. */
1247 smp_wmb();
1248 if (put_user(vq->last_used_idx, &vq->used->idx)) {
1249 vq_err(vq, "Failed to increment used idx");
1250 return -EFAULT;
1251 }
1252 if (unlikely(vq->log_used)) {
1253 /* Log used index update. */
1254 log_write(vq->log_base,
1255 vq->log_addr + offsetof(struct vring_used, idx),
1256 sizeof vq->used->idx);
1257 if (vq->log_ctx)
1258 eventfd_signal(vq->log_ctx, 1);
1259 }
1260 return r;
1261 }
1262
1263 /* This actually signals the guest, using eventfd. */
1264 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1265 {
1266 __u16 flags;
1267 /* Flush out used index updates. This is paired
1268 * with the barrier that the Guest executes when enabling
1269 * interrupts. */
1270 smp_mb();
1271
1272 if (get_user(flags, &vq->avail->flags)) {
1273 vq_err(vq, "Failed to get flags");
1274 return;
1275 }
1276
1277 /* If they don't want an interrupt, don't signal, unless empty. */
1278 if ((flags & VRING_AVAIL_F_NO_INTERRUPT) &&
1279 (vq->avail_idx != vq->last_avail_idx ||
1280 !vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY)))
1281 return;
1282
1283 /* Signal the Guest tell them we used something up. */
1284 if (vq->call_ctx)
1285 eventfd_signal(vq->call_ctx, 1);
1286 }
1287
1288 /* And here's the combo meal deal. Supersize me! */
1289 void vhost_add_used_and_signal(struct vhost_dev *dev,
1290 struct vhost_virtqueue *vq,
1291 unsigned int head, int len)
1292 {
1293 vhost_add_used(vq, head, len);
1294 vhost_signal(dev, vq);
1295 }
1296
1297 /* multi-buffer version of vhost_add_used_and_signal */
1298 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1299 struct vhost_virtqueue *vq,
1300 struct vring_used_elem *heads, unsigned count)
1301 {
1302 vhost_add_used_n(vq, heads, count);
1303 vhost_signal(dev, vq);
1304 }
1305
1306 /* OK, now we need to know about added descriptors. */
1307 bool vhost_enable_notify(struct vhost_virtqueue *vq)
1308 {
1309 u16 avail_idx;
1310 int r;
1311 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1312 return false;
1313 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1314 r = put_user(vq->used_flags, &vq->used->flags);
1315 if (r) {
1316 vq_err(vq, "Failed to enable notification at %p: %d\n",
1317 &vq->used->flags, r);
1318 return false;
1319 }
1320 /* They could have slipped one in as we were doing that: make
1321 * sure it's written, then check again. */
1322 smp_mb();
1323 r = get_user(avail_idx, &vq->avail->idx);
1324 if (r) {
1325 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1326 &vq->avail->idx, r);
1327 return false;
1328 }
1329
1330 return avail_idx != vq->avail_idx;
1331 }
1332
1333 /* We don't need to be notified again. */
1334 void vhost_disable_notify(struct vhost_virtqueue *vq)
1335 {
1336 int r;
1337 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1338 return;
1339 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1340 r = put_user(vq->used_flags, &vq->used->flags);
1341 if (r)
1342 vq_err(vq, "Failed to enable notification at %p: %d\n",
1343 &vq->used->flags, r);
1344 }
Linux kernel - Deliverables
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