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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Helpers for the host side of a virtio ring.
4 *
5 * Since these may be in userspace, we use (inline) accessors.
6 */
7#include <linux/compiler.h>
8#include <linux/module.h>
9#include <linux/vringh.h>
10#include <linux/virtio_ring.h>
11#include <linux/kernel.h>
12#include <linux/ratelimit.h>
13#include <linux/uaccess.h>
14#include <linux/slab.h>
15#include <linux/export.h>
16#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
17#include <linux/bvec.h>
18#include <linux/highmem.h>
19#include <linux/vhost_iotlb.h>
20#endif
21#include <uapi/linux/virtio_config.h>
22
23static __printf(1,2) __cold void vringh_bad(const char *fmt, ...)
24{
25 static DEFINE_RATELIMIT_STATE(vringh_rs,
26 DEFAULT_RATELIMIT_INTERVAL,
27 DEFAULT_RATELIMIT_BURST);
28 if (__ratelimit(&vringh_rs)) {
29 va_list ap;
30 va_start(ap, fmt);
31 printk(KERN_NOTICE "vringh:");
32 vprintk(fmt, ap);
33 va_end(ap);
34 }
35}
36
37/* Returns vring->num if empty, -ve on error. */
38static inline int __vringh_get_head(const struct vringh *vrh,
39 int (*getu16)(const struct vringh *vrh,
40 u16 *val, const __virtio16 *p),
41 u16 *last_avail_idx)
42{
43 u16 avail_idx, i, head;
44 int err;
45
46 err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx);
47 if (err) {
48 vringh_bad("Failed to access avail idx at %p",
49 &vrh->vring.avail->idx);
50 return err;
51 }
52
53 if (*last_avail_idx == avail_idx)
54 return vrh->vring.num;
55
56 /* Only get avail ring entries after they have been exposed by guest. */
57 virtio_rmb(vrh->weak_barriers);
58
59 i = *last_avail_idx & (vrh->vring.num - 1);
60
61 err = getu16(vrh, &head, &vrh->vring.avail->ring[i]);
62 if (err) {
63 vringh_bad("Failed to read head: idx %d address %p",
64 *last_avail_idx, &vrh->vring.avail->ring[i]);
65 return err;
66 }
67
68 if (head >= vrh->vring.num) {
69 vringh_bad("Guest says index %u > %u is available",
70 head, vrh->vring.num);
71 return -EINVAL;
72 }
73
74 (*last_avail_idx)++;
75 return head;
76}
77
78/**
79 * vringh_kiov_advance - skip bytes from vring_kiov
80 * @iov: an iov passed to vringh_getdesc_*() (updated as we consume)
81 * @len: the maximum length to advance
82 */
83void vringh_kiov_advance(struct vringh_kiov *iov, size_t len)
84{
85 while (len && iov->i < iov->used) {
86 size_t partlen = min(iov->iov[iov->i].iov_len, len);
87
88 iov->consumed += partlen;
89 iov->iov[iov->i].iov_len -= partlen;
90 iov->iov[iov->i].iov_base += partlen;
91
92 if (!iov->iov[iov->i].iov_len) {
93 /* Fix up old iov element then increment. */
94 iov->iov[iov->i].iov_len = iov->consumed;
95 iov->iov[iov->i].iov_base -= iov->consumed;
96
97 iov->consumed = 0;
98 iov->i++;
99 }
100
101 len -= partlen;
102 }
103}
104EXPORT_SYMBOL(vringh_kiov_advance);
105
106/* Copy some bytes to/from the iovec. Returns num copied. */
107static inline ssize_t vringh_iov_xfer(struct vringh *vrh,
108 struct vringh_kiov *iov,
109 void *ptr, size_t len,
110 int (*xfer)(const struct vringh *vrh,
111 void *addr, void *ptr,
112 size_t len))
113{
114 int err, done = 0;
115
116 while (len && iov->i < iov->used) {
117 size_t partlen;
118
119 partlen = min(iov->iov[iov->i].iov_len, len);
120 err = xfer(vrh, iov->iov[iov->i].iov_base, ptr, partlen);
121 if (err)
122 return err;
123 done += partlen;
124 len -= partlen;
125 ptr += partlen;
126
127 vringh_kiov_advance(iov, partlen);
128 }
129 return done;
130}
131
132/* May reduce *len if range is shorter. */
133static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len,
134 struct vringh_range *range,
135 bool (*getrange)(struct vringh *,
136 u64, struct vringh_range *))
137{
138 if (addr < range->start || addr > range->end_incl) {
139 if (!getrange(vrh, addr, range))
140 return false;
141 }
142 BUG_ON(addr < range->start || addr > range->end_incl);
143
144 /* To end of memory? */
145 if (unlikely(addr + *len == 0)) {
146 if (range->end_incl == -1ULL)
147 return true;
148 goto truncate;
149 }
150
151 /* Otherwise, don't wrap. */
152 if (addr + *len < addr) {
153 vringh_bad("Wrapping descriptor %zu@0x%llx",
154 *len, (unsigned long long)addr);
155 return false;
156 }
157
158 if (unlikely(addr + *len - 1 > range->end_incl))
159 goto truncate;
160 return true;
161
162truncate:
163 *len = range->end_incl + 1 - addr;
164 return true;
165}
166
167static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len,
168 struct vringh_range *range,
169 bool (*getrange)(struct vringh *,
170 u64, struct vringh_range *))
171{
172 return true;
173}
174
175/* No reason for this code to be inline. */
176static int move_to_indirect(const struct vringh *vrh,
177 int *up_next, u16 *i, void *addr,
178 const struct vring_desc *desc,
179 struct vring_desc **descs, int *desc_max)
180{
181 u32 len;
182
183 /* Indirect tables can't have indirect. */
184 if (*up_next != -1) {
185 vringh_bad("Multilevel indirect %u->%u", *up_next, *i);
186 return -EINVAL;
187 }
188
189 len = vringh32_to_cpu(vrh, desc->len);
190 if (unlikely(len % sizeof(struct vring_desc))) {
191 vringh_bad("Strange indirect len %u", desc->len);
192 return -EINVAL;
193 }
194
195 /* We will check this when we follow it! */
196 if (desc->flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT))
197 *up_next = vringh16_to_cpu(vrh, desc->next);
198 else
199 *up_next = -2;
200 *descs = addr;
201 *desc_max = len / sizeof(struct vring_desc);
202
203 /* Now, start at the first indirect. */
204 *i = 0;
205 return 0;
206}
207
208static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
209{
210 struct kvec *new;
211 unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;
212
213 if (new_num < 8)
214 new_num = 8;
215
216 flag = (iov->max_num & VRINGH_IOV_ALLOCATED);
217 if (flag)
218 new = krealloc_array(iov->iov, new_num,
219 sizeof(struct iovec), gfp);
220 else {
221 new = kmalloc_array(new_num, sizeof(struct iovec), gfp);
222 if (new) {
223 memcpy(new, iov->iov,
224 iov->max_num * sizeof(struct iovec));
225 flag = VRINGH_IOV_ALLOCATED;
226 }
227 }
228 if (!new)
229 return -ENOMEM;
230 iov->iov = new;
231 iov->max_num = (new_num | flag);
232 return 0;
233}
234
235static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next,
236 struct vring_desc **descs, int *desc_max)
237{
238 u16 i = *up_next;
239
240 *up_next = -1;
241 *descs = vrh->vring.desc;
242 *desc_max = vrh->vring.num;
243 return i;
244}
245
246static int slow_copy(struct vringh *vrh, void *dst, const void *src,
247 bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
248 struct vringh_range *range,
249 bool (*getrange)(struct vringh *vrh,
250 u64,
251 struct vringh_range *)),
252 bool (*getrange)(struct vringh *vrh,
253 u64 addr,
254 struct vringh_range *r),
255 struct vringh_range *range,
256 int (*copy)(const struct vringh *vrh,
257 void *dst, const void *src, size_t len))
258{
259 size_t part, len = sizeof(struct vring_desc);
260
261 do {
262 u64 addr;
263 int err;
264
265 part = len;
266 addr = (u64)(unsigned long)src - range->offset;
267
268 if (!rcheck(vrh, addr, &part, range, getrange))
269 return -EINVAL;
270
271 err = copy(vrh, dst, src, part);
272 if (err)
273 return err;
274
275 dst += part;
276 src += part;
277 len -= part;
278 } while (len);
279 return 0;
280}
281
282static inline int
283__vringh_iov(struct vringh *vrh, u16 i,
284 struct vringh_kiov *riov,
285 struct vringh_kiov *wiov,
286 bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
287 struct vringh_range *range,
288 bool (*getrange)(struct vringh *, u64,
289 struct vringh_range *)),
290 bool (*getrange)(struct vringh *, u64, struct vringh_range *),
291 gfp_t gfp,
292 int (*copy)(const struct vringh *vrh,
293 void *dst, const void *src, size_t len))
294{
295 int err, count = 0, indirect_count = 0, up_next, desc_max;
296 struct vring_desc desc, *descs;
297 struct vringh_range range = { -1ULL, 0 }, slowrange;
298 bool slow = false;
299
300 /* We start traversing vring's descriptor table. */
301 descs = vrh->vring.desc;
302 desc_max = vrh->vring.num;
303 up_next = -1;
304
305 /* You must want something! */
306 if (WARN_ON(!riov && !wiov))
307 return -EINVAL;
308
309 if (riov)
310 riov->i = riov->used = riov->consumed = 0;
311 if (wiov)
312 wiov->i = wiov->used = wiov->consumed = 0;
313
314 for (;;) {
315 void *addr;
316 struct vringh_kiov *iov;
317 size_t len;
318
319 if (unlikely(slow))
320 err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange,
321 &slowrange, copy);
322 else
323 err = copy(vrh, &desc, &descs[i], sizeof(desc));
324 if (unlikely(err))
325 goto fail;
326
327 if (unlikely(desc.flags &
328 cpu_to_vringh16(vrh, VRING_DESC_F_INDIRECT))) {
329 u64 a = vringh64_to_cpu(vrh, desc.addr);
330
331 /* Make sure it's OK, and get offset. */
332 len = vringh32_to_cpu(vrh, desc.len);
333 if (!rcheck(vrh, a, &len, &range, getrange)) {
334 err = -EINVAL;
335 goto fail;
336 }
337
338 if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
339 slow = true;
340 /* We need to save this range to use offset */
341 slowrange = range;
342 }
343
344 addr = (void *)(long)(a + range.offset);
345 err = move_to_indirect(vrh, &up_next, &i, addr, &desc,
346 &descs, &desc_max);
347 if (err)
348 goto fail;
349 continue;
350 }
351
352 if (up_next == -1)
353 count++;
354 else
355 indirect_count++;
356
357 if (count > vrh->vring.num || indirect_count > desc_max) {
358 vringh_bad("Descriptor loop in %p", descs);
359 err = -ELOOP;
360 goto fail;
361 }
362
363 if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_WRITE))
364 iov = wiov;
365 else {
366 iov = riov;
367 if (unlikely(wiov && wiov->used)) {
368 vringh_bad("Readable desc %p after writable",
369 &descs[i]);
370 err = -EINVAL;
371 goto fail;
372 }
373 }
374
375 if (!iov) {
376 vringh_bad("Unexpected %s desc",
377 !wiov ? "writable" : "readable");
378 err = -EPROTO;
379 goto fail;
380 }
381
382 again:
383 /* Make sure it's OK, and get offset. */
384 len = vringh32_to_cpu(vrh, desc.len);
385 if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range,
386 getrange)) {
387 err = -EINVAL;
388 goto fail;
389 }
390 addr = (void *)(unsigned long)(vringh64_to_cpu(vrh, desc.addr) +
391 range.offset);
392
393 if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) {
394 err = resize_iovec(iov, gfp);
395 if (err)
396 goto fail;
397 }
398
399 iov->iov[iov->used].iov_base = addr;
400 iov->iov[iov->used].iov_len = len;
401 iov->used++;
402
403 if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
404 desc.len = cpu_to_vringh32(vrh,
405 vringh32_to_cpu(vrh, desc.len) - len);
406 desc.addr = cpu_to_vringh64(vrh,
407 vringh64_to_cpu(vrh, desc.addr) + len);
408 goto again;
409 }
410
411 if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) {
412 i = vringh16_to_cpu(vrh, desc.next);
413 } else {
414 /* Just in case we need to finish traversing above. */
415 if (unlikely(up_next > 0)) {
416 i = return_from_indirect(vrh, &up_next,
417 &descs, &desc_max);
418 slow = false;
419 indirect_count = 0;
420 } else
421 break;
422 }
423
424 if (i >= desc_max) {
425 vringh_bad("Chained index %u > %u", i, desc_max);
426 err = -EINVAL;
427 goto fail;
428 }
429 }
430
431 return 0;
432
433fail:
434 return err;
435}
436
437static inline int __vringh_complete(struct vringh *vrh,
438 const struct vring_used_elem *used,
439 unsigned int num_used,
440 int (*putu16)(const struct vringh *vrh,
441 __virtio16 *p, u16 val),
442 int (*putused)(const struct vringh *vrh,
443 struct vring_used_elem *dst,
444 const struct vring_used_elem
445 *src, unsigned num))
446{
447 struct vring_used *used_ring;
448 int err;
449 u16 used_idx, off;
450
451 used_ring = vrh->vring.used;
452 used_idx = vrh->last_used_idx + vrh->completed;
453
454 off = used_idx % vrh->vring.num;
455
456 /* Compiler knows num_used == 1 sometimes, hence extra check */
457 if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) {
458 u16 part = vrh->vring.num - off;
459 err = putused(vrh, &used_ring->ring[off], used, part);
460 if (!err)
461 err = putused(vrh, &used_ring->ring[0], used + part,
462 num_used - part);
463 } else
464 err = putused(vrh, &used_ring->ring[off], used, num_used);
465
466 if (err) {
467 vringh_bad("Failed to write %u used entries %u at %p",
468 num_used, off, &used_ring->ring[off]);
469 return err;
470 }
471
472 /* Make sure buffer is written before we update index. */
473 virtio_wmb(vrh->weak_barriers);
474
475 err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used);
476 if (err) {
477 vringh_bad("Failed to update used index at %p",
478 &vrh->vring.used->idx);
479 return err;
480 }
481
482 vrh->completed += num_used;
483 return 0;
484}
485
486
487static inline int __vringh_need_notify(struct vringh *vrh,
488 int (*getu16)(const struct vringh *vrh,
489 u16 *val,
490 const __virtio16 *p))
491{
492 bool notify;
493 u16 used_event;
494 int err;
495
496 /* Flush out used index update. This is paired with the
497 * barrier that the Guest executes when enabling
498 * interrupts. */
499 virtio_mb(vrh->weak_barriers);
500
501 /* Old-style, without event indices. */
502 if (!vrh->event_indices) {
503 u16 flags;
504 err = getu16(vrh, &flags, &vrh->vring.avail->flags);
505 if (err) {
506 vringh_bad("Failed to get flags at %p",
507 &vrh->vring.avail->flags);
508 return err;
509 }
510 return (!(flags & VRING_AVAIL_F_NO_INTERRUPT));
511 }
512
513 /* Modern: we know when other side wants to know. */
514 err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring));
515 if (err) {
516 vringh_bad("Failed to get used event idx at %p",
517 &vring_used_event(&vrh->vring));
518 return err;
519 }
520
521 /* Just in case we added so many that we wrap. */
522 if (unlikely(vrh->completed > 0xffff))
523 notify = true;
524 else
525 notify = vring_need_event(used_event,
526 vrh->last_used_idx + vrh->completed,
527 vrh->last_used_idx);
528
529 vrh->last_used_idx += vrh->completed;
530 vrh->completed = 0;
531 return notify;
532}
533
534static inline bool __vringh_notify_enable(struct vringh *vrh,
535 int (*getu16)(const struct vringh *vrh,
536 u16 *val, const __virtio16 *p),
537 int (*putu16)(const struct vringh *vrh,
538 __virtio16 *p, u16 val))
539{
540 u16 avail;
541
542 if (!vrh->event_indices) {
543 /* Old-school; update flags. */
544 if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) {
545 vringh_bad("Clearing used flags %p",
546 &vrh->vring.used->flags);
547 return true;
548 }
549 } else {
550 if (putu16(vrh, &vring_avail_event(&vrh->vring),
551 vrh->last_avail_idx) != 0) {
552 vringh_bad("Updating avail event index %p",
553 &vring_avail_event(&vrh->vring));
554 return true;
555 }
556 }
557
558 /* They could have slipped one in as we were doing that: make
559 * sure it's written, then check again. */
560 virtio_mb(vrh->weak_barriers);
561
562 if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) {
563 vringh_bad("Failed to check avail idx at %p",
564 &vrh->vring.avail->idx);
565 return true;
566 }
567
568 /* This is unlikely, so we just leave notifications enabled
569 * (if we're using event_indices, we'll only get one
570 * notification anyway). */
571 return avail == vrh->last_avail_idx;
572}
573
574static inline void __vringh_notify_disable(struct vringh *vrh,
575 int (*putu16)(const struct vringh *vrh,
576 __virtio16 *p, u16 val))
577{
578 if (!vrh->event_indices) {
579 /* Old-school; update flags. */
580 if (putu16(vrh, &vrh->vring.used->flags,
581 VRING_USED_F_NO_NOTIFY)) {
582 vringh_bad("Setting used flags %p",
583 &vrh->vring.used->flags);
584 }
585 }
586}
587
588/* Userspace access helpers: in this case, addresses are really userspace. */
589static inline int getu16_user(const struct vringh *vrh, u16 *val, const __virtio16 *p)
590{
591 __virtio16 v = 0;
592 int rc = get_user(v, (__force __virtio16 __user *)p);
593 *val = vringh16_to_cpu(vrh, v);
594 return rc;
595}
596
597static inline int putu16_user(const struct vringh *vrh, __virtio16 *p, u16 val)
598{
599 __virtio16 v = cpu_to_vringh16(vrh, val);
600 return put_user(v, (__force __virtio16 __user *)p);
601}
602
603static inline int copydesc_user(const struct vringh *vrh,
604 void *dst, const void *src, size_t len)
605{
606 return copy_from_user(dst, (__force void __user *)src, len) ?
607 -EFAULT : 0;
608}
609
610static inline int putused_user(const struct vringh *vrh,
611 struct vring_used_elem *dst,
612 const struct vring_used_elem *src,
613 unsigned int num)
614{
615 return copy_to_user((__force void __user *)dst, src,
616 sizeof(*dst) * num) ? -EFAULT : 0;
617}
618
619static inline int xfer_from_user(const struct vringh *vrh, void *src,
620 void *dst, size_t len)
621{
622 return copy_from_user(dst, (__force void __user *)src, len) ?
623 -EFAULT : 0;
624}
625
626static inline int xfer_to_user(const struct vringh *vrh,
627 void *dst, void *src, size_t len)
628{
629 return copy_to_user((__force void __user *)dst, src, len) ?
630 -EFAULT : 0;
631}
632
633/**
634 * vringh_init_user - initialize a vringh for a userspace vring.
635 * @vrh: the vringh to initialize.
636 * @features: the feature bits for this ring.
637 * @num: the number of elements.
638 * @weak_barriers: true if we only need memory barriers, not I/O.
639 * @desc: the userpace descriptor pointer.
640 * @avail: the userpace avail pointer.
641 * @used: the userpace used pointer.
642 *
643 * Returns an error if num is invalid: you should check pointers
644 * yourself!
645 */
646int vringh_init_user(struct vringh *vrh, u64 features,
647 unsigned int num, bool weak_barriers,
648 vring_desc_t __user *desc,
649 vring_avail_t __user *avail,
650 vring_used_t __user *used)
651{
652 /* Sane power of 2 please! */
653 if (!num || num > 0xffff || (num & (num - 1))) {
654 vringh_bad("Bad ring size %u", num);
655 return -EINVAL;
656 }
657
658 vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
659 vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
660 vrh->weak_barriers = weak_barriers;
661 vrh->completed = 0;
662 vrh->last_avail_idx = 0;
663 vrh->last_used_idx = 0;
664 vrh->vring.num = num;
665 /* vring expects kernel addresses, but only used via accessors. */
666 vrh->vring.desc = (__force struct vring_desc *)desc;
667 vrh->vring.avail = (__force struct vring_avail *)avail;
668 vrh->vring.used = (__force struct vring_used *)used;
669 return 0;
670}
671EXPORT_SYMBOL(vringh_init_user);
672
673/**
674 * vringh_getdesc_user - get next available descriptor from userspace ring.
675 * @vrh: the userspace vring.
676 * @riov: where to put the readable descriptors (or NULL)
677 * @wiov: where to put the writable descriptors (or NULL)
678 * @getrange: function to call to check ranges.
679 * @head: head index we received, for passing to vringh_complete_user().
680 *
681 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
682 *
683 * Note that on error return, you can tell the difference between an
684 * invalid ring and a single invalid descriptor: in the former case,
685 * *head will be vrh->vring.num. You may be able to ignore an invalid
686 * descriptor, but there's not much you can do with an invalid ring.
687 *
688 * Note that you can reuse riov and wiov with subsequent calls. Content is
689 * overwritten and memory reallocated if more space is needed.
690 * When you don't have to use riov and wiov anymore, you should clean up them
691 * calling vringh_iov_cleanup() to release the memory, even on error!
692 */
693int vringh_getdesc_user(struct vringh *vrh,
694 struct vringh_iov *riov,
695 struct vringh_iov *wiov,
696 bool (*getrange)(struct vringh *vrh,
697 u64 addr, struct vringh_range *r),
698 u16 *head)
699{
700 int err;
701
702 *head = vrh->vring.num;
703 err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx);
704 if (err < 0)
705 return err;
706
707 /* Empty... */
708 if (err == vrh->vring.num)
709 return 0;
710
711 /* We need the layouts to be the identical for this to work */
712 BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov));
713 BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) !=
714 offsetof(struct vringh_iov, iov));
715 BUILD_BUG_ON(offsetof(struct vringh_kiov, i) !=
716 offsetof(struct vringh_iov, i));
717 BUILD_BUG_ON(offsetof(struct vringh_kiov, used) !=
718 offsetof(struct vringh_iov, used));
719 BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) !=
720 offsetof(struct vringh_iov, max_num));
721 BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
722 BUILD_BUG_ON(offsetof(struct iovec, iov_base) !=
723 offsetof(struct kvec, iov_base));
724 BUILD_BUG_ON(offsetof(struct iovec, iov_len) !=
725 offsetof(struct kvec, iov_len));
726 BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base)
727 != sizeof(((struct kvec *)NULL)->iov_base));
728 BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len)
729 != sizeof(((struct kvec *)NULL)->iov_len));
730
731 *head = err;
732 err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
733 (struct vringh_kiov *)wiov,
734 range_check, getrange, GFP_KERNEL, copydesc_user);
735 if (err)
736 return err;
737
738 return 1;
739}
740EXPORT_SYMBOL(vringh_getdesc_user);
741
742/**
743 * vringh_iov_pull_user - copy bytes from vring_iov.
744 * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume)
745 * @dst: the place to copy.
746 * @len: the maximum length to copy.
747 *
748 * Returns the bytes copied <= len or a negative errno.
749 */
750ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len)
751{
752 return vringh_iov_xfer(NULL, (struct vringh_kiov *)riov,
753 dst, len, xfer_from_user);
754}
755EXPORT_SYMBOL(vringh_iov_pull_user);
756
757/**
758 * vringh_iov_push_user - copy bytes into vring_iov.
759 * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume)
760 * @src: the place to copy from.
761 * @len: the maximum length to copy.
762 *
763 * Returns the bytes copied <= len or a negative errno.
764 */
765ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
766 const void *src, size_t len)
767{
768 return vringh_iov_xfer(NULL, (struct vringh_kiov *)wiov,
769 (void *)src, len, xfer_to_user);
770}
771EXPORT_SYMBOL(vringh_iov_push_user);
772
773/**
774 * vringh_abandon_user - we've decided not to handle the descriptor(s).
775 * @vrh: the vring.
776 * @num: the number of descriptors to put back (ie. num
777 * vringh_get_user() to undo).
778 *
779 * The next vringh_get_user() will return the old descriptor(s) again.
780 */
781void vringh_abandon_user(struct vringh *vrh, unsigned int num)
782{
783 /* We only update vring_avail_event(vr) when we want to be notified,
784 * so we haven't changed that yet. */
785 vrh->last_avail_idx -= num;
786}
787EXPORT_SYMBOL(vringh_abandon_user);
788
789/**
790 * vringh_complete_user - we've finished with descriptor, publish it.
791 * @vrh: the vring.
792 * @head: the head as filled in by vringh_getdesc_user.
793 * @len: the length of data we have written.
794 *
795 * You should check vringh_need_notify_user() after one or more calls
796 * to this function.
797 */
798int vringh_complete_user(struct vringh *vrh, u16 head, u32 len)
799{
800 struct vring_used_elem used;
801
802 used.id = cpu_to_vringh32(vrh, head);
803 used.len = cpu_to_vringh32(vrh, len);
804 return __vringh_complete(vrh, &used, 1, putu16_user, putused_user);
805}
806EXPORT_SYMBOL(vringh_complete_user);
807
808/**
809 * vringh_complete_multi_user - we've finished with many descriptors.
810 * @vrh: the vring.
811 * @used: the head, length pairs.
812 * @num_used: the number of used elements.
813 *
814 * You should check vringh_need_notify_user() after one or more calls
815 * to this function.
816 */
817int vringh_complete_multi_user(struct vringh *vrh,
818 const struct vring_used_elem used[],
819 unsigned num_used)
820{
821 return __vringh_complete(vrh, used, num_used,
822 putu16_user, putused_user);
823}
824EXPORT_SYMBOL(vringh_complete_multi_user);
825
826/**
827 * vringh_notify_enable_user - we want to know if something changes.
828 * @vrh: the vring.
829 *
830 * This always enables notifications, but returns false if there are
831 * now more buffers available in the vring.
832 */
833bool vringh_notify_enable_user(struct vringh *vrh)
834{
835 return __vringh_notify_enable(vrh, getu16_user, putu16_user);
836}
837EXPORT_SYMBOL(vringh_notify_enable_user);
838
839/**
840 * vringh_notify_disable_user - don't tell us if something changes.
841 * @vrh: the vring.
842 *
843 * This is our normal running state: we disable and then only enable when
844 * we're going to sleep.
845 */
846void vringh_notify_disable_user(struct vringh *vrh)
847{
848 __vringh_notify_disable(vrh, putu16_user);
849}
850EXPORT_SYMBOL(vringh_notify_disable_user);
851
852/**
853 * vringh_need_notify_user - must we tell the other side about used buffers?
854 * @vrh: the vring we've called vringh_complete_user() on.
855 *
856 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
857 */
858int vringh_need_notify_user(struct vringh *vrh)
859{
860 return __vringh_need_notify(vrh, getu16_user);
861}
862EXPORT_SYMBOL(vringh_need_notify_user);
863
864/* Kernelspace access helpers. */
865static inline int getu16_kern(const struct vringh *vrh,
866 u16 *val, const __virtio16 *p)
867{
868 *val = vringh16_to_cpu(vrh, READ_ONCE(*p));
869 return 0;
870}
871
872static inline int putu16_kern(const struct vringh *vrh, __virtio16 *p, u16 val)
873{
874 WRITE_ONCE(*p, cpu_to_vringh16(vrh, val));
875 return 0;
876}
877
878static inline int copydesc_kern(const struct vringh *vrh,
879 void *dst, const void *src, size_t len)
880{
881 memcpy(dst, src, len);
882 return 0;
883}
884
885static inline int putused_kern(const struct vringh *vrh,
886 struct vring_used_elem *dst,
887 const struct vring_used_elem *src,
888 unsigned int num)
889{
890 memcpy(dst, src, num * sizeof(*dst));
891 return 0;
892}
893
894static inline int xfer_kern(const struct vringh *vrh, void *src,
895 void *dst, size_t len)
896{
897 memcpy(dst, src, len);
898 return 0;
899}
900
901static inline int kern_xfer(const struct vringh *vrh, void *dst,
902 void *src, size_t len)
903{
904 memcpy(dst, src, len);
905 return 0;
906}
907
908/**
909 * vringh_init_kern - initialize a vringh for a kernelspace vring.
910 * @vrh: the vringh to initialize.
911 * @features: the feature bits for this ring.
912 * @num: the number of elements.
913 * @weak_barriers: true if we only need memory barriers, not I/O.
914 * @desc: the userpace descriptor pointer.
915 * @avail: the userpace avail pointer.
916 * @used: the userpace used pointer.
917 *
918 * Returns an error if num is invalid.
919 */
920int vringh_init_kern(struct vringh *vrh, u64 features,
921 unsigned int num, bool weak_barriers,
922 struct vring_desc *desc,
923 struct vring_avail *avail,
924 struct vring_used *used)
925{
926 /* Sane power of 2 please! */
927 if (!num || num > 0xffff || (num & (num - 1))) {
928 vringh_bad("Bad ring size %u", num);
929 return -EINVAL;
930 }
931
932 vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
933 vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
934 vrh->weak_barriers = weak_barriers;
935 vrh->completed = 0;
936 vrh->last_avail_idx = 0;
937 vrh->last_used_idx = 0;
938 vrh->vring.num = num;
939 vrh->vring.desc = desc;
940 vrh->vring.avail = avail;
941 vrh->vring.used = used;
942 return 0;
943}
944EXPORT_SYMBOL(vringh_init_kern);
945
946/**
947 * vringh_getdesc_kern - get next available descriptor from kernelspace ring.
948 * @vrh: the kernelspace vring.
949 * @riov: where to put the readable descriptors (or NULL)
950 * @wiov: where to put the writable descriptors (or NULL)
951 * @head: head index we received, for passing to vringh_complete_kern().
952 * @gfp: flags for allocating larger riov/wiov.
953 *
954 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
955 *
956 * Note that on error return, you can tell the difference between an
957 * invalid ring and a single invalid descriptor: in the former case,
958 * *head will be vrh->vring.num. You may be able to ignore an invalid
959 * descriptor, but there's not much you can do with an invalid ring.
960 *
961 * Note that you can reuse riov and wiov with subsequent calls. Content is
962 * overwritten and memory reallocated if more space is needed.
963 * When you don't have to use riov and wiov anymore, you should clean up them
964 * calling vringh_kiov_cleanup() to release the memory, even on error!
965 */
966int vringh_getdesc_kern(struct vringh *vrh,
967 struct vringh_kiov *riov,
968 struct vringh_kiov *wiov,
969 u16 *head,
970 gfp_t gfp)
971{
972 int err;
973
974 err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx);
975 if (err < 0)
976 return err;
977
978 /* Empty... */
979 if (err == vrh->vring.num)
980 return 0;
981
982 *head = err;
983 err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
984 gfp, copydesc_kern);
985 if (err)
986 return err;
987
988 return 1;
989}
990EXPORT_SYMBOL(vringh_getdesc_kern);
991
992/**
993 * vringh_iov_pull_kern - copy bytes from vring_iov.
994 * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume)
995 * @dst: the place to copy.
996 * @len: the maximum length to copy.
997 *
998 * Returns the bytes copied <= len or a negative errno.
999 */
1000ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len)
1001{
1002 return vringh_iov_xfer(NULL, riov, dst, len, xfer_kern);
1003}
1004EXPORT_SYMBOL(vringh_iov_pull_kern);
1005
1006/**
1007 * vringh_iov_push_kern - copy bytes into vring_iov.
1008 * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume)
1009 * @src: the place to copy from.
1010 * @len: the maximum length to copy.
1011 *
1012 * Returns the bytes copied <= len or a negative errno.
1013 */
1014ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
1015 const void *src, size_t len)
1016{
1017 return vringh_iov_xfer(NULL, wiov, (void *)src, len, kern_xfer);
1018}
1019EXPORT_SYMBOL(vringh_iov_push_kern);
1020
1021/**
1022 * vringh_abandon_kern - we've decided not to handle the descriptor(s).
1023 * @vrh: the vring.
1024 * @num: the number of descriptors to put back (ie. num
1025 * vringh_get_kern() to undo).
1026 *
1027 * The next vringh_get_kern() will return the old descriptor(s) again.
1028 */
1029void vringh_abandon_kern(struct vringh *vrh, unsigned int num)
1030{
1031 /* We only update vring_avail_event(vr) when we want to be notified,
1032 * so we haven't changed that yet. */
1033 vrh->last_avail_idx -= num;
1034}
1035EXPORT_SYMBOL(vringh_abandon_kern);
1036
1037/**
1038 * vringh_complete_kern - we've finished with descriptor, publish it.
1039 * @vrh: the vring.
1040 * @head: the head as filled in by vringh_getdesc_kern.
1041 * @len: the length of data we have written.
1042 *
1043 * You should check vringh_need_notify_kern() after one or more calls
1044 * to this function.
1045 */
1046int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len)
1047{
1048 struct vring_used_elem used;
1049
1050 used.id = cpu_to_vringh32(vrh, head);
1051 used.len = cpu_to_vringh32(vrh, len);
1052
1053 return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern);
1054}
1055EXPORT_SYMBOL(vringh_complete_kern);
1056
1057/**
1058 * vringh_notify_enable_kern - we want to know if something changes.
1059 * @vrh: the vring.
1060 *
1061 * This always enables notifications, but returns false if there are
1062 * now more buffers available in the vring.
1063 */
1064bool vringh_notify_enable_kern(struct vringh *vrh)
1065{
1066 return __vringh_notify_enable(vrh, getu16_kern, putu16_kern);
1067}
1068EXPORT_SYMBOL(vringh_notify_enable_kern);
1069
1070/**
1071 * vringh_notify_disable_kern - don't tell us if something changes.
1072 * @vrh: the vring.
1073 *
1074 * This is our normal running state: we disable and then only enable when
1075 * we're going to sleep.
1076 */
1077void vringh_notify_disable_kern(struct vringh *vrh)
1078{
1079 __vringh_notify_disable(vrh, putu16_kern);
1080}
1081EXPORT_SYMBOL(vringh_notify_disable_kern);
1082
1083/**
1084 * vringh_need_notify_kern - must we tell the other side about used buffers?
1085 * @vrh: the vring we've called vringh_complete_kern() on.
1086 *
1087 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
1088 */
1089int vringh_need_notify_kern(struct vringh *vrh)
1090{
1091 return __vringh_need_notify(vrh, getu16_kern);
1092}
1093EXPORT_SYMBOL(vringh_need_notify_kern);
1094
1095#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
1096
1097static int iotlb_translate(const struct vringh *vrh,
1098 u64 addr, u64 len, u64 *translated,
1099 struct bio_vec iov[],
1100 int iov_size, u32 perm)
1101{
1102 struct vhost_iotlb_map *map;
1103 struct vhost_iotlb *iotlb = vrh->iotlb;
1104 int ret = 0;
1105 u64 s = 0, last = addr + len - 1;
1106
1107 spin_lock(vrh->iotlb_lock);
1108
1109 while (len > s) {
1110 u64 size, pa, pfn;
1111
1112 if (unlikely(ret >= iov_size)) {
1113 ret = -ENOBUFS;
1114 break;
1115 }
1116
1117 map = vhost_iotlb_itree_first(iotlb, addr, last);
1118 if (!map || map->start > addr) {
1119 ret = -EINVAL;
1120 break;
1121 } else if (!(map->perm & perm)) {
1122 ret = -EPERM;
1123 break;
1124 }
1125
1126 size = map->size - addr + map->start;
1127 pa = map->addr + addr - map->start;
1128 pfn = pa >> PAGE_SHIFT;
1129 iov[ret].bv_page = pfn_to_page(pfn);
1130 iov[ret].bv_len = min(len - s, size);
1131 iov[ret].bv_offset = pa & (PAGE_SIZE - 1);
1132 s += size;
1133 addr += size;
1134 ++ret;
1135 }
1136
1137 spin_unlock(vrh->iotlb_lock);
1138
1139 if (translated)
1140 *translated = min(len, s);
1141
1142 return ret;
1143}
1144
1145static inline int copy_from_iotlb(const struct vringh *vrh, void *dst,
1146 void *src, size_t len)
1147{
1148 u64 total_translated = 0;
1149
1150 while (total_translated < len) {
1151 struct bio_vec iov[16];
1152 struct iov_iter iter;
1153 u64 translated;
1154 int ret;
1155
1156 ret = iotlb_translate(vrh, (u64)(uintptr_t)src,
1157 len - total_translated, &translated,
1158 iov, ARRAY_SIZE(iov), VHOST_MAP_RO);
1159 if (ret == -ENOBUFS)
1160 ret = ARRAY_SIZE(iov);
1161 else if (ret < 0)
1162 return ret;
1163
1164 iov_iter_bvec(&iter, ITER_SOURCE, iov, ret, translated);
1165
1166 ret = copy_from_iter(dst, translated, &iter);
1167 if (ret < 0)
1168 return ret;
1169
1170 src += translated;
1171 dst += translated;
1172 total_translated += translated;
1173 }
1174
1175 return total_translated;
1176}
1177
1178static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
1179 void *src, size_t len)
1180{
1181 u64 total_translated = 0;
1182
1183 while (total_translated < len) {
1184 struct bio_vec iov[16];
1185 struct iov_iter iter;
1186 u64 translated;
1187 int ret;
1188
1189 ret = iotlb_translate(vrh, (u64)(uintptr_t)dst,
1190 len - total_translated, &translated,
1191 iov, ARRAY_SIZE(iov), VHOST_MAP_WO);
1192 if (ret == -ENOBUFS)
1193 ret = ARRAY_SIZE(iov);
1194 else if (ret < 0)
1195 return ret;
1196
1197 iov_iter_bvec(&iter, ITER_DEST, iov, ret, translated);
1198
1199 ret = copy_to_iter(src, translated, &iter);
1200 if (ret < 0)
1201 return ret;
1202
1203 src += translated;
1204 dst += translated;
1205 total_translated += translated;
1206 }
1207
1208 return total_translated;
1209}
1210
1211static inline int getu16_iotlb(const struct vringh *vrh,
1212 u16 *val, const __virtio16 *p)
1213{
1214 struct bio_vec iov;
1215 void *kaddr, *from;
1216 int ret;
1217
1218 /* Atomic read is needed for getu16 */
1219 ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p), NULL,
1220 &iov, 1, VHOST_MAP_RO);
1221 if (ret < 0)
1222 return ret;
1223
1224 kaddr = kmap_atomic(iov.bv_page);
1225 from = kaddr + iov.bv_offset;
1226 *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from));
1227 kunmap_atomic(kaddr);
1228
1229 return 0;
1230}
1231
1232static inline int putu16_iotlb(const struct vringh *vrh,
1233 __virtio16 *p, u16 val)
1234{
1235 struct bio_vec iov;
1236 void *kaddr, *to;
1237 int ret;
1238
1239 /* Atomic write is needed for putu16 */
1240 ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p), NULL,
1241 &iov, 1, VHOST_MAP_WO);
1242 if (ret < 0)
1243 return ret;
1244
1245 kaddr = kmap_atomic(iov.bv_page);
1246 to = kaddr + iov.bv_offset;
1247 WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val));
1248 kunmap_atomic(kaddr);
1249
1250 return 0;
1251}
1252
1253static inline int copydesc_iotlb(const struct vringh *vrh,
1254 void *dst, const void *src, size_t len)
1255{
1256 int ret;
1257
1258 ret = copy_from_iotlb(vrh, dst, (void *)src, len);
1259 if (ret != len)
1260 return -EFAULT;
1261
1262 return 0;
1263}
1264
1265static inline int xfer_from_iotlb(const struct vringh *vrh, void *src,
1266 void *dst, size_t len)
1267{
1268 int ret;
1269
1270 ret = copy_from_iotlb(vrh, dst, src, len);
1271 if (ret != len)
1272 return -EFAULT;
1273
1274 return 0;
1275}
1276
1277static inline int xfer_to_iotlb(const struct vringh *vrh,
1278 void *dst, void *src, size_t len)
1279{
1280 int ret;
1281
1282 ret = copy_to_iotlb(vrh, dst, src, len);
1283 if (ret != len)
1284 return -EFAULT;
1285
1286 return 0;
1287}
1288
1289static inline int putused_iotlb(const struct vringh *vrh,
1290 struct vring_used_elem *dst,
1291 const struct vring_used_elem *src,
1292 unsigned int num)
1293{
1294 int size = num * sizeof(*dst);
1295 int ret;
1296
1297 ret = copy_to_iotlb(vrh, dst, (void *)src, num * sizeof(*dst));
1298 if (ret != size)
1299 return -EFAULT;
1300
1301 return 0;
1302}
1303
1304/**
1305 * vringh_init_iotlb - initialize a vringh for a ring with IOTLB.
1306 * @vrh: the vringh to initialize.
1307 * @features: the feature bits for this ring.
1308 * @num: the number of elements.
1309 * @weak_barriers: true if we only need memory barriers, not I/O.
1310 * @desc: the userpace descriptor pointer.
1311 * @avail: the userpace avail pointer.
1312 * @used: the userpace used pointer.
1313 *
1314 * Returns an error if num is invalid.
1315 */
1316int vringh_init_iotlb(struct vringh *vrh, u64 features,
1317 unsigned int num, bool weak_barriers,
1318 struct vring_desc *desc,
1319 struct vring_avail *avail,
1320 struct vring_used *used)
1321{
1322 return vringh_init_kern(vrh, features, num, weak_barriers,
1323 desc, avail, used);
1324}
1325EXPORT_SYMBOL(vringh_init_iotlb);
1326
1327/**
1328 * vringh_set_iotlb - initialize a vringh for a ring with IOTLB.
1329 * @vrh: the vring
1330 * @iotlb: iotlb associated with this vring
1331 * @iotlb_lock: spinlock to synchronize the iotlb accesses
1332 */
1333void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb,
1334 spinlock_t *iotlb_lock)
1335{
1336 vrh->iotlb = iotlb;
1337 vrh->iotlb_lock = iotlb_lock;
1338}
1339EXPORT_SYMBOL(vringh_set_iotlb);
1340
1341/**
1342 * vringh_getdesc_iotlb - get next available descriptor from ring with
1343 * IOTLB.
1344 * @vrh: the kernelspace vring.
1345 * @riov: where to put the readable descriptors (or NULL)
1346 * @wiov: where to put the writable descriptors (or NULL)
1347 * @head: head index we received, for passing to vringh_complete_iotlb().
1348 * @gfp: flags for allocating larger riov/wiov.
1349 *
1350 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
1351 *
1352 * Note that on error return, you can tell the difference between an
1353 * invalid ring and a single invalid descriptor: in the former case,
1354 * *head will be vrh->vring.num. You may be able to ignore an invalid
1355 * descriptor, but there's not much you can do with an invalid ring.
1356 *
1357 * Note that you can reuse riov and wiov with subsequent calls. Content is
1358 * overwritten and memory reallocated if more space is needed.
1359 * When you don't have to use riov and wiov anymore, you should clean up them
1360 * calling vringh_kiov_cleanup() to release the memory, even on error!
1361 */
1362int vringh_getdesc_iotlb(struct vringh *vrh,
1363 struct vringh_kiov *riov,
1364 struct vringh_kiov *wiov,
1365 u16 *head,
1366 gfp_t gfp)
1367{
1368 int err;
1369
1370 err = __vringh_get_head(vrh, getu16_iotlb, &vrh->last_avail_idx);
1371 if (err < 0)
1372 return err;
1373
1374 /* Empty... */
1375 if (err == vrh->vring.num)
1376 return 0;
1377
1378 *head = err;
1379 err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
1380 gfp, copydesc_iotlb);
1381 if (err)
1382 return err;
1383
1384 return 1;
1385}
1386EXPORT_SYMBOL(vringh_getdesc_iotlb);
1387
1388/**
1389 * vringh_iov_pull_iotlb - copy bytes from vring_iov.
1390 * @vrh: the vring.
1391 * @riov: the riov as passed to vringh_getdesc_iotlb() (updated as we consume)
1392 * @dst: the place to copy.
1393 * @len: the maximum length to copy.
1394 *
1395 * Returns the bytes copied <= len or a negative errno.
1396 */
1397ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
1398 struct vringh_kiov *riov,
1399 void *dst, size_t len)
1400{
1401 return vringh_iov_xfer(vrh, riov, dst, len, xfer_from_iotlb);
1402}
1403EXPORT_SYMBOL(vringh_iov_pull_iotlb);
1404
1405/**
1406 * vringh_iov_push_iotlb - copy bytes into vring_iov.
1407 * @vrh: the vring.
1408 * @wiov: the wiov as passed to vringh_getdesc_iotlb() (updated as we consume)
1409 * @src: the place to copy from.
1410 * @len: the maximum length to copy.
1411 *
1412 * Returns the bytes copied <= len or a negative errno.
1413 */
1414ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
1415 struct vringh_kiov *wiov,
1416 const void *src, size_t len)
1417{
1418 return vringh_iov_xfer(vrh, wiov, (void *)src, len, xfer_to_iotlb);
1419}
1420EXPORT_SYMBOL(vringh_iov_push_iotlb);
1421
1422/**
1423 * vringh_abandon_iotlb - we've decided not to handle the descriptor(s).
1424 * @vrh: the vring.
1425 * @num: the number of descriptors to put back (ie. num
1426 * vringh_get_iotlb() to undo).
1427 *
1428 * The next vringh_get_iotlb() will return the old descriptor(s) again.
1429 */
1430void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num)
1431{
1432 /* We only update vring_avail_event(vr) when we want to be notified,
1433 * so we haven't changed that yet.
1434 */
1435 vrh->last_avail_idx -= num;
1436}
1437EXPORT_SYMBOL(vringh_abandon_iotlb);
1438
1439/**
1440 * vringh_complete_iotlb - we've finished with descriptor, publish it.
1441 * @vrh: the vring.
1442 * @head: the head as filled in by vringh_getdesc_iotlb.
1443 * @len: the length of data we have written.
1444 *
1445 * You should check vringh_need_notify_iotlb() after one or more calls
1446 * to this function.
1447 */
1448int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len)
1449{
1450 struct vring_used_elem used;
1451
1452 used.id = cpu_to_vringh32(vrh, head);
1453 used.len = cpu_to_vringh32(vrh, len);
1454
1455 return __vringh_complete(vrh, &used, 1, putu16_iotlb, putused_iotlb);
1456}
1457EXPORT_SYMBOL(vringh_complete_iotlb);
1458
1459/**
1460 * vringh_notify_enable_iotlb - we want to know if something changes.
1461 * @vrh: the vring.
1462 *
1463 * This always enables notifications, but returns false if there are
1464 * now more buffers available in the vring.
1465 */
1466bool vringh_notify_enable_iotlb(struct vringh *vrh)
1467{
1468 return __vringh_notify_enable(vrh, getu16_iotlb, putu16_iotlb);
1469}
1470EXPORT_SYMBOL(vringh_notify_enable_iotlb);
1471
1472/**
1473 * vringh_notify_disable_iotlb - don't tell us if something changes.
1474 * @vrh: the vring.
1475 *
1476 * This is our normal running state: we disable and then only enable when
1477 * we're going to sleep.
1478 */
1479void vringh_notify_disable_iotlb(struct vringh *vrh)
1480{
1481 __vringh_notify_disable(vrh, putu16_iotlb);
1482}
1483EXPORT_SYMBOL(vringh_notify_disable_iotlb);
1484
1485/**
1486 * vringh_need_notify_iotlb - must we tell the other side about used buffers?
1487 * @vrh: the vring we've called vringh_complete_iotlb() on.
1488 *
1489 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
1490 */
1491int vringh_need_notify_iotlb(struct vringh *vrh)
1492{
1493 return __vringh_need_notify(vrh, getu16_iotlb);
1494}
1495EXPORT_SYMBOL(vringh_need_notify_iotlb);
1496
1497#endif
1498
1499MODULE_LICENSE("GPL");