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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 iov->consumed += partlen;
127 iov->iov[iov->i].iov_len -= partlen;
128 iov->iov[iov->i].iov_base += partlen;
129
130 if (!iov->iov[iov->i].iov_len) {
131 /* Fix up old iov element then increment. */
132 iov->iov[iov->i].iov_len = iov->consumed;
133 iov->iov[iov->i].iov_base -= iov->consumed;
134
135 iov->consumed = 0;
136 iov->i++;
137 }
138 }
139 return done;
140}
141
142/* May reduce *len if range is shorter. */
143static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len,
144 struct vringh_range *range,
145 bool (*getrange)(struct vringh *,
146 u64, struct vringh_range *))
147{
148 if (addr < range->start || addr > range->end_incl) {
149 if (!getrange(vrh, addr, range))
150 return false;
151 }
152 BUG_ON(addr < range->start || addr > range->end_incl);
153
154 /* To end of memory? */
155 if (unlikely(addr + *len == 0)) {
156 if (range->end_incl == -1ULL)
157 return true;
158 goto truncate;
159 }
160
161 /* Otherwise, don't wrap. */
162 if (addr + *len < addr) {
163 vringh_bad("Wrapping descriptor %zu@0x%llx",
164 *len, (unsigned long long)addr);
165 return false;
166 }
167
168 if (unlikely(addr + *len - 1 > range->end_incl))
169 goto truncate;
170 return true;
171
172truncate:
173 *len = range->end_incl + 1 - addr;
174 return true;
175}
176
177static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len,
178 struct vringh_range *range,
179 bool (*getrange)(struct vringh *,
180 u64, struct vringh_range *))
181{
182 return true;
183}
184
185/* No reason for this code to be inline. */
186static int move_to_indirect(const struct vringh *vrh,
187 int *up_next, u16 *i, void *addr,
188 const struct vring_desc *desc,
189 struct vring_desc **descs, int *desc_max)
190{
191 u32 len;
192
193 /* Indirect tables can't have indirect. */
194 if (*up_next != -1) {
195 vringh_bad("Multilevel indirect %u->%u", *up_next, *i);
196 return -EINVAL;
197 }
198
199 len = vringh32_to_cpu(vrh, desc->len);
200 if (unlikely(len % sizeof(struct vring_desc))) {
201 vringh_bad("Strange indirect len %u", desc->len);
202 return -EINVAL;
203 }
204
205 /* We will check this when we follow it! */
206 if (desc->flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT))
207 *up_next = vringh16_to_cpu(vrh, desc->next);
208 else
209 *up_next = -2;
210 *descs = addr;
211 *desc_max = len / sizeof(struct vring_desc);
212
213 /* Now, start at the first indirect. */
214 *i = 0;
215 return 0;
216}
217
218static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
219{
220 struct kvec *new;
221 unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;
222
223 if (new_num < 8)
224 new_num = 8;
225
226 flag = (iov->max_num & VRINGH_IOV_ALLOCATED);
227 if (flag)
228 new = krealloc_array(iov->iov, new_num,
229 sizeof(struct iovec), gfp);
230 else {
231 new = kmalloc_array(new_num, sizeof(struct iovec), gfp);
232 if (new) {
233 memcpy(new, iov->iov,
234 iov->max_num * sizeof(struct iovec));
235 flag = VRINGH_IOV_ALLOCATED;
236 }
237 }
238 if (!new)
239 return -ENOMEM;
240 iov->iov = new;
241 iov->max_num = (new_num | flag);
242 return 0;
243}
244
245static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next,
246 struct vring_desc **descs, int *desc_max)
247{
248 u16 i = *up_next;
249
250 *up_next = -1;
251 *descs = vrh->vring.desc;
252 *desc_max = vrh->vring.num;
253 return i;
254}
255
256static int slow_copy(struct vringh *vrh, void *dst, const void *src,
257 bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
258 struct vringh_range *range,
259 bool (*getrange)(struct vringh *vrh,
260 u64,
261 struct vringh_range *)),
262 bool (*getrange)(struct vringh *vrh,
263 u64 addr,
264 struct vringh_range *r),
265 struct vringh_range *range,
266 int (*copy)(const struct vringh *vrh,
267 void *dst, const void *src, size_t len))
268{
269 size_t part, len = sizeof(struct vring_desc);
270
271 do {
272 u64 addr;
273 int err;
274
275 part = len;
276 addr = (u64)(unsigned long)src - range->offset;
277
278 if (!rcheck(vrh, addr, &part, range, getrange))
279 return -EINVAL;
280
281 err = copy(vrh, dst, src, part);
282 if (err)
283 return err;
284
285 dst += part;
286 src += part;
287 len -= part;
288 } while (len);
289 return 0;
290}
291
292static inline int
293__vringh_iov(struct vringh *vrh, u16 i,
294 struct vringh_kiov *riov,
295 struct vringh_kiov *wiov,
296 bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
297 struct vringh_range *range,
298 bool (*getrange)(struct vringh *, u64,
299 struct vringh_range *)),
300 bool (*getrange)(struct vringh *, u64, struct vringh_range *),
301 gfp_t gfp,
302 int (*copy)(const struct vringh *vrh,
303 void *dst, const void *src, size_t len))
304{
305 int err, count = 0, indirect_count = 0, up_next, desc_max;
306 struct vring_desc desc, *descs;
307 struct vringh_range range = { -1ULL, 0 }, slowrange;
308 bool slow = false;
309
310 /* We start traversing vring's descriptor table. */
311 descs = vrh->vring.desc;
312 desc_max = vrh->vring.num;
313 up_next = -1;
314
315 /* You must want something! */
316 if (WARN_ON(!riov && !wiov))
317 return -EINVAL;
318
319 if (riov)
320 riov->i = riov->used = riov->consumed = 0;
321 if (wiov)
322 wiov->i = wiov->used = wiov->consumed = 0;
323
324 for (;;) {
325 void *addr;
326 struct vringh_kiov *iov;
327 size_t len;
328
329 if (unlikely(slow))
330 err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange,
331 &slowrange, copy);
332 else
333 err = copy(vrh, &desc, &descs[i], sizeof(desc));
334 if (unlikely(err))
335 goto fail;
336
337 if (unlikely(desc.flags &
338 cpu_to_vringh16(vrh, VRING_DESC_F_INDIRECT))) {
339 u64 a = vringh64_to_cpu(vrh, desc.addr);
340
341 /* Make sure it's OK, and get offset. */
342 len = vringh32_to_cpu(vrh, desc.len);
343 if (!rcheck(vrh, a, &len, &range, getrange)) {
344 err = -EINVAL;
345 goto fail;
346 }
347
348 if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
349 slow = true;
350 /* We need to save this range to use offset */
351 slowrange = range;
352 }
353
354 addr = (void *)(long)(a + range.offset);
355 err = move_to_indirect(vrh, &up_next, &i, addr, &desc,
356 &descs, &desc_max);
357 if (err)
358 goto fail;
359 continue;
360 }
361
362 if (up_next == -1)
363 count++;
364 else
365 indirect_count++;
366
367 if (count > vrh->vring.num || indirect_count > desc_max) {
368 vringh_bad("Descriptor loop in %p", descs);
369 err = -ELOOP;
370 goto fail;
371 }
372
373 if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_WRITE))
374 iov = wiov;
375 else {
376 iov = riov;
377 if (unlikely(wiov && wiov->used)) {
378 vringh_bad("Readable desc %p after writable",
379 &descs[i]);
380 err = -EINVAL;
381 goto fail;
382 }
383 }
384
385 if (!iov) {
386 vringh_bad("Unexpected %s desc",
387 !wiov ? "writable" : "readable");
388 err = -EPROTO;
389 goto fail;
390 }
391
392 again:
393 /* Make sure it's OK, and get offset. */
394 len = vringh32_to_cpu(vrh, desc.len);
395 if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range,
396 getrange)) {
397 err = -EINVAL;
398 goto fail;
399 }
400 addr = (void *)(unsigned long)(vringh64_to_cpu(vrh, desc.addr) +
401 range.offset);
402
403 if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) {
404 err = resize_iovec(iov, gfp);
405 if (err)
406 goto fail;
407 }
408
409 iov->iov[iov->used].iov_base = addr;
410 iov->iov[iov->used].iov_len = len;
411 iov->used++;
412
413 if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
414 desc.len = cpu_to_vringh32(vrh,
415 vringh32_to_cpu(vrh, desc.len) - len);
416 desc.addr = cpu_to_vringh64(vrh,
417 vringh64_to_cpu(vrh, desc.addr) + len);
418 goto again;
419 }
420
421 if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) {
422 i = vringh16_to_cpu(vrh, desc.next);
423 } else {
424 /* Just in case we need to finish traversing above. */
425 if (unlikely(up_next > 0)) {
426 i = return_from_indirect(vrh, &up_next,
427 &descs, &desc_max);
428 slow = false;
429 indirect_count = 0;
430 } else
431 break;
432 }
433
434 if (i >= desc_max) {
435 vringh_bad("Chained index %u > %u", i, desc_max);
436 err = -EINVAL;
437 goto fail;
438 }
439 }
440
441 return 0;
442
443fail:
444 return err;
445}
446
447static inline int __vringh_complete(struct vringh *vrh,
448 const struct vring_used_elem *used,
449 unsigned int num_used,
450 int (*putu16)(const struct vringh *vrh,
451 __virtio16 *p, u16 val),
452 int (*putused)(const struct vringh *vrh,
453 struct vring_used_elem *dst,
454 const struct vring_used_elem
455 *src, unsigned num))
456{
457 struct vring_used *used_ring;
458 int err;
459 u16 used_idx, off;
460
461 used_ring = vrh->vring.used;
462 used_idx = vrh->last_used_idx + vrh->completed;
463
464 off = used_idx % vrh->vring.num;
465
466 /* Compiler knows num_used == 1 sometimes, hence extra check */
467 if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) {
468 u16 part = vrh->vring.num - off;
469 err = putused(vrh, &used_ring->ring[off], used, part);
470 if (!err)
471 err = putused(vrh, &used_ring->ring[0], used + part,
472 num_used - part);
473 } else
474 err = putused(vrh, &used_ring->ring[off], used, num_used);
475
476 if (err) {
477 vringh_bad("Failed to write %u used entries %u at %p",
478 num_used, off, &used_ring->ring[off]);
479 return err;
480 }
481
482 /* Make sure buffer is written before we update index. */
483 virtio_wmb(vrh->weak_barriers);
484
485 err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used);
486 if (err) {
487 vringh_bad("Failed to update used index at %p",
488 &vrh->vring.used->idx);
489 return err;
490 }
491
492 vrh->completed += num_used;
493 return 0;
494}
495
496
497static inline int __vringh_need_notify(struct vringh *vrh,
498 int (*getu16)(const struct vringh *vrh,
499 u16 *val,
500 const __virtio16 *p))
501{
502 bool notify;
503 u16 used_event;
504 int err;
505
506 /* Flush out used index update. This is paired with the
507 * barrier that the Guest executes when enabling
508 * interrupts. */
509 virtio_mb(vrh->weak_barriers);
510
511 /* Old-style, without event indices. */
512 if (!vrh->event_indices) {
513 u16 flags;
514 err = getu16(vrh, &flags, &vrh->vring.avail->flags);
515 if (err) {
516 vringh_bad("Failed to get flags at %p",
517 &vrh->vring.avail->flags);
518 return err;
519 }
520 return (!(flags & VRING_AVAIL_F_NO_INTERRUPT));
521 }
522
523 /* Modern: we know when other side wants to know. */
524 err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring));
525 if (err) {
526 vringh_bad("Failed to get used event idx at %p",
527 &vring_used_event(&vrh->vring));
528 return err;
529 }
530
531 /* Just in case we added so many that we wrap. */
532 if (unlikely(vrh->completed > 0xffff))
533 notify = true;
534 else
535 notify = vring_need_event(used_event,
536 vrh->last_used_idx + vrh->completed,
537 vrh->last_used_idx);
538
539 vrh->last_used_idx += vrh->completed;
540 vrh->completed = 0;
541 return notify;
542}
543
544static inline bool __vringh_notify_enable(struct vringh *vrh,
545 int (*getu16)(const struct vringh *vrh,
546 u16 *val, const __virtio16 *p),
547 int (*putu16)(const struct vringh *vrh,
548 __virtio16 *p, u16 val))
549{
550 u16 avail;
551
552 if (!vrh->event_indices) {
553 /* Old-school; update flags. */
554 if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) {
555 vringh_bad("Clearing used flags %p",
556 &vrh->vring.used->flags);
557 return true;
558 }
559 } else {
560 if (putu16(vrh, &vring_avail_event(&vrh->vring),
561 vrh->last_avail_idx) != 0) {
562 vringh_bad("Updating avail event index %p",
563 &vring_avail_event(&vrh->vring));
564 return true;
565 }
566 }
567
568 /* They could have slipped one in as we were doing that: make
569 * sure it's written, then check again. */
570 virtio_mb(vrh->weak_barriers);
571
572 if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) {
573 vringh_bad("Failed to check avail idx at %p",
574 &vrh->vring.avail->idx);
575 return true;
576 }
577
578 /* This is unlikely, so we just leave notifications enabled
579 * (if we're using event_indices, we'll only get one
580 * notification anyway). */
581 return avail == vrh->last_avail_idx;
582}
583
584static inline void __vringh_notify_disable(struct vringh *vrh,
585 int (*putu16)(const struct vringh *vrh,
586 __virtio16 *p, u16 val))
587{
588 if (!vrh->event_indices) {
589 /* Old-school; update flags. */
590 if (putu16(vrh, &vrh->vring.used->flags,
591 VRING_USED_F_NO_NOTIFY)) {
592 vringh_bad("Setting used flags %p",
593 &vrh->vring.used->flags);
594 }
595 }
596}
597
598/* Userspace access helpers: in this case, addresses are really userspace. */
599static inline int getu16_user(const struct vringh *vrh, u16 *val, const __virtio16 *p)
600{
601 __virtio16 v = 0;
602 int rc = get_user(v, (__force __virtio16 __user *)p);
603 *val = vringh16_to_cpu(vrh, v);
604 return rc;
605}
606
607static inline int putu16_user(const struct vringh *vrh, __virtio16 *p, u16 val)
608{
609 __virtio16 v = cpu_to_vringh16(vrh, val);
610 return put_user(v, (__force __virtio16 __user *)p);
611}
612
613static inline int copydesc_user(const struct vringh *vrh,
614 void *dst, const void *src, size_t len)
615{
616 return copy_from_user(dst, (__force void __user *)src, len) ?
617 -EFAULT : 0;
618}
619
620static inline int putused_user(const struct vringh *vrh,
621 struct vring_used_elem *dst,
622 const struct vring_used_elem *src,
623 unsigned int num)
624{
625 return copy_to_user((__force void __user *)dst, src,
626 sizeof(*dst) * num) ? -EFAULT : 0;
627}
628
629static inline int xfer_from_user(const struct vringh *vrh, void *src,
630 void *dst, size_t len)
631{
632 return copy_from_user(dst, (__force void __user *)src, len) ?
633 -EFAULT : 0;
634}
635
636static inline int xfer_to_user(const struct vringh *vrh,
637 void *dst, void *src, size_t len)
638{
639 return copy_to_user((__force void __user *)dst, src, len) ?
640 -EFAULT : 0;
641}
642
643/**
644 * vringh_init_user - initialize a vringh for a userspace vring.
645 * @vrh: the vringh to initialize.
646 * @features: the feature bits for this ring.
647 * @num: the number of elements.
648 * @weak_barriers: true if we only need memory barriers, not I/O.
649 * @desc: the userspace descriptor pointer.
650 * @avail: the userspace avail pointer.
651 * @used: the userspace used pointer.
652 *
653 * Returns an error if num is invalid: you should check pointers
654 * yourself!
655 */
656int vringh_init_user(struct vringh *vrh, u64 features,
657 unsigned int num, bool weak_barriers,
658 vring_desc_t __user *desc,
659 vring_avail_t __user *avail,
660 vring_used_t __user *used)
661{
662 /* Sane power of 2 please! */
663 if (!num || num > 0xffff || (num & (num - 1))) {
664 vringh_bad("Bad ring size %u", num);
665 return -EINVAL;
666 }
667
668 vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
669 vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
670 vrh->weak_barriers = weak_barriers;
671 vrh->completed = 0;
672 vrh->last_avail_idx = 0;
673 vrh->last_used_idx = 0;
674 vrh->vring.num = num;
675 /* vring expects kernel addresses, but only used via accessors. */
676 vrh->vring.desc = (__force struct vring_desc *)desc;
677 vrh->vring.avail = (__force struct vring_avail *)avail;
678 vrh->vring.used = (__force struct vring_used *)used;
679 return 0;
680}
681EXPORT_SYMBOL(vringh_init_user);
682
683/**
684 * vringh_getdesc_user - get next available descriptor from userspace ring.
685 * @vrh: the userspace vring.
686 * @riov: where to put the readable descriptors (or NULL)
687 * @wiov: where to put the writable descriptors (or NULL)
688 * @getrange: function to call to check ranges.
689 * @head: head index we received, for passing to vringh_complete_user().
690 *
691 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
692 *
693 * Note that on error return, you can tell the difference between an
694 * invalid ring and a single invalid descriptor: in the former case,
695 * *head will be vrh->vring.num. You may be able to ignore an invalid
696 * descriptor, but there's not much you can do with an invalid ring.
697 *
698 * Note that you can reuse riov and wiov with subsequent calls. Content is
699 * overwritten and memory reallocated if more space is needed.
700 * When you don't have to use riov and wiov anymore, you should clean up them
701 * calling vringh_iov_cleanup() to release the memory, even on error!
702 */
703int vringh_getdesc_user(struct vringh *vrh,
704 struct vringh_iov *riov,
705 struct vringh_iov *wiov,
706 bool (*getrange)(struct vringh *vrh,
707 u64 addr, struct vringh_range *r),
708 u16 *head)
709{
710 int err;
711
712 *head = vrh->vring.num;
713 err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx);
714 if (err < 0)
715 return err;
716
717 /* Empty... */
718 if (err == vrh->vring.num)
719 return 0;
720
721 /* We need the layouts to be the identical for this to work */
722 BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov));
723 BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) !=
724 offsetof(struct vringh_iov, iov));
725 BUILD_BUG_ON(offsetof(struct vringh_kiov, i) !=
726 offsetof(struct vringh_iov, i));
727 BUILD_BUG_ON(offsetof(struct vringh_kiov, used) !=
728 offsetof(struct vringh_iov, used));
729 BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) !=
730 offsetof(struct vringh_iov, max_num));
731 BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
732 BUILD_BUG_ON(offsetof(struct iovec, iov_base) !=
733 offsetof(struct kvec, iov_base));
734 BUILD_BUG_ON(offsetof(struct iovec, iov_len) !=
735 offsetof(struct kvec, iov_len));
736 BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base)
737 != sizeof(((struct kvec *)NULL)->iov_base));
738 BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len)
739 != sizeof(((struct kvec *)NULL)->iov_len));
740
741 *head = err;
742 err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
743 (struct vringh_kiov *)wiov,
744 range_check, getrange, GFP_KERNEL, copydesc_user);
745 if (err)
746 return err;
747
748 return 1;
749}
750EXPORT_SYMBOL(vringh_getdesc_user);
751
752/**
753 * vringh_iov_pull_user - copy bytes from vring_iov.
754 * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume)
755 * @dst: the place to copy.
756 * @len: the maximum length to copy.
757 *
758 * Returns the bytes copied <= len or a negative errno.
759 */
760ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len)
761{
762 return vringh_iov_xfer(NULL, (struct vringh_kiov *)riov,
763 dst, len, xfer_from_user);
764}
765EXPORT_SYMBOL(vringh_iov_pull_user);
766
767/**
768 * vringh_iov_push_user - copy bytes into vring_iov.
769 * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume)
770 * @src: the place to copy from.
771 * @len: the maximum length to copy.
772 *
773 * Returns the bytes copied <= len or a negative errno.
774 */
775ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
776 const void *src, size_t len)
777{
778 return vringh_iov_xfer(NULL, (struct vringh_kiov *)wiov,
779 (void *)src, len, xfer_to_user);
780}
781EXPORT_SYMBOL(vringh_iov_push_user);
782
783/**
784 * vringh_abandon_user - we've decided not to handle the descriptor(s).
785 * @vrh: the vring.
786 * @num: the number of descriptors to put back (ie. num
787 * vringh_get_user() to undo).
788 *
789 * The next vringh_get_user() will return the old descriptor(s) again.
790 */
791void vringh_abandon_user(struct vringh *vrh, unsigned int num)
792{
793 /* We only update vring_avail_event(vr) when we want to be notified,
794 * so we haven't changed that yet. */
795 vrh->last_avail_idx -= num;
796}
797EXPORT_SYMBOL(vringh_abandon_user);
798
799/**
800 * vringh_complete_user - we've finished with descriptor, publish it.
801 * @vrh: the vring.
802 * @head: the head as filled in by vringh_getdesc_user.
803 * @len: the length of data we have written.
804 *
805 * You should check vringh_need_notify_user() after one or more calls
806 * to this function.
807 */
808int vringh_complete_user(struct vringh *vrh, u16 head, u32 len)
809{
810 struct vring_used_elem used;
811
812 used.id = cpu_to_vringh32(vrh, head);
813 used.len = cpu_to_vringh32(vrh, len);
814 return __vringh_complete(vrh, &used, 1, putu16_user, putused_user);
815}
816EXPORT_SYMBOL(vringh_complete_user);
817
818/**
819 * vringh_complete_multi_user - we've finished with many descriptors.
820 * @vrh: the vring.
821 * @used: the head, length pairs.
822 * @num_used: the number of used elements.
823 *
824 * You should check vringh_need_notify_user() after one or more calls
825 * to this function.
826 */
827int vringh_complete_multi_user(struct vringh *vrh,
828 const struct vring_used_elem used[],
829 unsigned num_used)
830{
831 return __vringh_complete(vrh, used, num_used,
832 putu16_user, putused_user);
833}
834EXPORT_SYMBOL(vringh_complete_multi_user);
835
836/**
837 * vringh_notify_enable_user - we want to know if something changes.
838 * @vrh: the vring.
839 *
840 * This always enables notifications, but returns false if there are
841 * now more buffers available in the vring.
842 */
843bool vringh_notify_enable_user(struct vringh *vrh)
844{
845 return __vringh_notify_enable(vrh, getu16_user, putu16_user);
846}
847EXPORT_SYMBOL(vringh_notify_enable_user);
848
849/**
850 * vringh_notify_disable_user - don't tell us if something changes.
851 * @vrh: the vring.
852 *
853 * This is our normal running state: we disable and then only enable when
854 * we're going to sleep.
855 */
856void vringh_notify_disable_user(struct vringh *vrh)
857{
858 __vringh_notify_disable(vrh, putu16_user);
859}
860EXPORT_SYMBOL(vringh_notify_disable_user);
861
862/**
863 * vringh_need_notify_user - must we tell the other side about used buffers?
864 * @vrh: the vring we've called vringh_complete_user() on.
865 *
866 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
867 */
868int vringh_need_notify_user(struct vringh *vrh)
869{
870 return __vringh_need_notify(vrh, getu16_user);
871}
872EXPORT_SYMBOL(vringh_need_notify_user);
873
874/* Kernelspace access helpers. */
875static inline int getu16_kern(const struct vringh *vrh,
876 u16 *val, const __virtio16 *p)
877{
878 *val = vringh16_to_cpu(vrh, READ_ONCE(*p));
879 return 0;
880}
881
882static inline int putu16_kern(const struct vringh *vrh, __virtio16 *p, u16 val)
883{
884 WRITE_ONCE(*p, cpu_to_vringh16(vrh, val));
885 return 0;
886}
887
888static inline int copydesc_kern(const struct vringh *vrh,
889 void *dst, const void *src, size_t len)
890{
891 memcpy(dst, src, len);
892 return 0;
893}
894
895static inline int putused_kern(const struct vringh *vrh,
896 struct vring_used_elem *dst,
897 const struct vring_used_elem *src,
898 unsigned int num)
899{
900 memcpy(dst, src, num * sizeof(*dst));
901 return 0;
902}
903
904static inline int xfer_kern(const struct vringh *vrh, void *src,
905 void *dst, size_t len)
906{
907 memcpy(dst, src, len);
908 return 0;
909}
910
911static inline int kern_xfer(const struct vringh *vrh, void *dst,
912 void *src, size_t len)
913{
914 memcpy(dst, src, len);
915 return 0;
916}
917
918/**
919 * vringh_init_kern - initialize a vringh for a kernelspace vring.
920 * @vrh: the vringh to initialize.
921 * @features: the feature bits for this ring.
922 * @num: the number of elements.
923 * @weak_barriers: true if we only need memory barriers, not I/O.
924 * @desc: the userspace descriptor pointer.
925 * @avail: the userspace avail pointer.
926 * @used: the userspace used pointer.
927 *
928 * Returns an error if num is invalid.
929 */
930int vringh_init_kern(struct vringh *vrh, u64 features,
931 unsigned int num, bool weak_barriers,
932 struct vring_desc *desc,
933 struct vring_avail *avail,
934 struct vring_used *used)
935{
936 /* Sane power of 2 please! */
937 if (!num || num > 0xffff || (num & (num - 1))) {
938 vringh_bad("Bad ring size %u", num);
939 return -EINVAL;
940 }
941
942 vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
943 vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
944 vrh->weak_barriers = weak_barriers;
945 vrh->completed = 0;
946 vrh->last_avail_idx = 0;
947 vrh->last_used_idx = 0;
948 vrh->vring.num = num;
949 vrh->vring.desc = desc;
950 vrh->vring.avail = avail;
951 vrh->vring.used = used;
952 return 0;
953}
954EXPORT_SYMBOL(vringh_init_kern);
955
956/**
957 * vringh_getdesc_kern - get next available descriptor from kernelspace ring.
958 * @vrh: the kernelspace vring.
959 * @riov: where to put the readable descriptors (or NULL)
960 * @wiov: where to put the writable descriptors (or NULL)
961 * @head: head index we received, for passing to vringh_complete_kern().
962 * @gfp: flags for allocating larger riov/wiov.
963 *
964 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
965 *
966 * Note that on error return, you can tell the difference between an
967 * invalid ring and a single invalid descriptor: in the former case,
968 * *head will be vrh->vring.num. You may be able to ignore an invalid
969 * descriptor, but there's not much you can do with an invalid ring.
970 *
971 * Note that you can reuse riov and wiov with subsequent calls. Content is
972 * overwritten and memory reallocated if more space is needed.
973 * When you don't have to use riov and wiov anymore, you should clean up them
974 * calling vringh_kiov_cleanup() to release the memory, even on error!
975 */
976int vringh_getdesc_kern(struct vringh *vrh,
977 struct vringh_kiov *riov,
978 struct vringh_kiov *wiov,
979 u16 *head,
980 gfp_t gfp)
981{
982 int err;
983
984 err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx);
985 if (err < 0)
986 return err;
987
988 /* Empty... */
989 if (err == vrh->vring.num)
990 return 0;
991
992 *head = err;
993 err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
994 gfp, copydesc_kern);
995 if (err)
996 return err;
997
998 return 1;
999}
1000EXPORT_SYMBOL(vringh_getdesc_kern);
1001
1002/**
1003 * vringh_iov_pull_kern - copy bytes from vring_iov.
1004 * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume)
1005 * @dst: the place to copy.
1006 * @len: the maximum length to copy.
1007 *
1008 * Returns the bytes copied <= len or a negative errno.
1009 */
1010ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len)
1011{
1012 return vringh_iov_xfer(NULL, riov, dst, len, xfer_kern);
1013}
1014EXPORT_SYMBOL(vringh_iov_pull_kern);
1015
1016/**
1017 * vringh_iov_push_kern - copy bytes into vring_iov.
1018 * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume)
1019 * @src: the place to copy from.
1020 * @len: the maximum length to copy.
1021 *
1022 * Returns the bytes copied <= len or a negative errno.
1023 */
1024ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
1025 const void *src, size_t len)
1026{
1027 return vringh_iov_xfer(NULL, wiov, (void *)src, len, kern_xfer);
1028}
1029EXPORT_SYMBOL(vringh_iov_push_kern);
1030
1031/**
1032 * vringh_abandon_kern - we've decided not to handle the descriptor(s).
1033 * @vrh: the vring.
1034 * @num: the number of descriptors to put back (ie. num
1035 * vringh_get_kern() to undo).
1036 *
1037 * The next vringh_get_kern() will return the old descriptor(s) again.
1038 */
1039void vringh_abandon_kern(struct vringh *vrh, unsigned int num)
1040{
1041 /* We only update vring_avail_event(vr) when we want to be notified,
1042 * so we haven't changed that yet. */
1043 vrh->last_avail_idx -= num;
1044}
1045EXPORT_SYMBOL(vringh_abandon_kern);
1046
1047/**
1048 * vringh_complete_kern - we've finished with descriptor, publish it.
1049 * @vrh: the vring.
1050 * @head: the head as filled in by vringh_getdesc_kern.
1051 * @len: the length of data we have written.
1052 *
1053 * You should check vringh_need_notify_kern() after one or more calls
1054 * to this function.
1055 */
1056int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len)
1057{
1058 struct vring_used_elem used;
1059
1060 used.id = cpu_to_vringh32(vrh, head);
1061 used.len = cpu_to_vringh32(vrh, len);
1062
1063 return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern);
1064}
1065EXPORT_SYMBOL(vringh_complete_kern);
1066
1067/**
1068 * vringh_notify_enable_kern - we want to know if something changes.
1069 * @vrh: the vring.
1070 *
1071 * This always enables notifications, but returns false if there are
1072 * now more buffers available in the vring.
1073 */
1074bool vringh_notify_enable_kern(struct vringh *vrh)
1075{
1076 return __vringh_notify_enable(vrh, getu16_kern, putu16_kern);
1077}
1078EXPORT_SYMBOL(vringh_notify_enable_kern);
1079
1080/**
1081 * vringh_notify_disable_kern - don't tell us if something changes.
1082 * @vrh: the vring.
1083 *
1084 * This is our normal running state: we disable and then only enable when
1085 * we're going to sleep.
1086 */
1087void vringh_notify_disable_kern(struct vringh *vrh)
1088{
1089 __vringh_notify_disable(vrh, putu16_kern);
1090}
1091EXPORT_SYMBOL(vringh_notify_disable_kern);
1092
1093/**
1094 * vringh_need_notify_kern - must we tell the other side about used buffers?
1095 * @vrh: the vring we've called vringh_complete_kern() on.
1096 *
1097 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
1098 */
1099int vringh_need_notify_kern(struct vringh *vrh)
1100{
1101 return __vringh_need_notify(vrh, getu16_kern);
1102}
1103EXPORT_SYMBOL(vringh_need_notify_kern);
1104
1105#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
1106
1107struct iotlb_vec {
1108 union {
1109 struct iovec *iovec;
1110 struct bio_vec *bvec;
1111 } iov;
1112 size_t count;
1113};
1114
1115static int iotlb_translate(const struct vringh *vrh,
1116 u64 addr, u64 len, u64 *translated,
1117 struct iotlb_vec *ivec, u32 perm)
1118{
1119 struct vhost_iotlb_map *map;
1120 struct vhost_iotlb *iotlb = vrh->iotlb;
1121 int ret = 0;
1122 u64 s = 0, last = addr + len - 1;
1123
1124 spin_lock(vrh->iotlb_lock);
1125
1126 while (len > s) {
1127 uintptr_t io_addr;
1128 size_t io_len;
1129 u64 size;
1130
1131 if (unlikely(ret >= ivec->count)) {
1132 ret = -ENOBUFS;
1133 break;
1134 }
1135
1136 map = vhost_iotlb_itree_first(iotlb, addr, last);
1137 if (!map || map->start > addr) {
1138 ret = -EINVAL;
1139 break;
1140 } else if (!(map->perm & perm)) {
1141 ret = -EPERM;
1142 break;
1143 }
1144
1145 size = map->size - addr + map->start;
1146 io_len = min(len - s, size);
1147 io_addr = map->addr - map->start + addr;
1148
1149 if (vrh->use_va) {
1150 struct iovec *iovec = ivec->iov.iovec;
1151
1152 iovec[ret].iov_len = io_len;
1153 iovec[ret].iov_base = (void __user *)io_addr;
1154 } else {
1155 u64 pfn = io_addr >> PAGE_SHIFT;
1156 struct bio_vec *bvec = ivec->iov.bvec;
1157
1158 bvec_set_page(&bvec[ret], pfn_to_page(pfn), io_len,
1159 io_addr & (PAGE_SIZE - 1));
1160 }
1161
1162 s += size;
1163 addr += size;
1164 ++ret;
1165 }
1166
1167 spin_unlock(vrh->iotlb_lock);
1168
1169 if (translated)
1170 *translated = min(len, s);
1171
1172 return ret;
1173}
1174
1175#define IOTLB_IOV_STRIDE 16
1176
1177static inline int copy_from_iotlb(const struct vringh *vrh, void *dst,
1178 void *src, size_t len)
1179{
1180 struct iotlb_vec ivec;
1181 union {
1182 struct iovec iovec[IOTLB_IOV_STRIDE];
1183 struct bio_vec bvec[IOTLB_IOV_STRIDE];
1184 } iov;
1185 u64 total_translated = 0;
1186
1187 ivec.iov.iovec = iov.iovec;
1188 ivec.count = IOTLB_IOV_STRIDE;
1189
1190 while (total_translated < len) {
1191 struct iov_iter iter;
1192 u64 translated;
1193 int ret;
1194
1195 ret = iotlb_translate(vrh, (u64)(uintptr_t)src,
1196 len - total_translated, &translated,
1197 &ivec, VHOST_MAP_RO);
1198 if (ret == -ENOBUFS)
1199 ret = IOTLB_IOV_STRIDE;
1200 else if (ret < 0)
1201 return ret;
1202
1203 if (vrh->use_va) {
1204 iov_iter_init(&iter, ITER_SOURCE, ivec.iov.iovec, ret,
1205 translated);
1206 } else {
1207 iov_iter_bvec(&iter, ITER_SOURCE, ivec.iov.bvec, ret,
1208 translated);
1209 }
1210
1211 ret = copy_from_iter(dst, translated, &iter);
1212 if (ret < 0)
1213 return ret;
1214
1215 src += translated;
1216 dst += translated;
1217 total_translated += translated;
1218 }
1219
1220 return total_translated;
1221}
1222
1223static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
1224 void *src, size_t len)
1225{
1226 struct iotlb_vec ivec;
1227 union {
1228 struct iovec iovec[IOTLB_IOV_STRIDE];
1229 struct bio_vec bvec[IOTLB_IOV_STRIDE];
1230 } iov;
1231 u64 total_translated = 0;
1232
1233 ivec.iov.iovec = iov.iovec;
1234 ivec.count = IOTLB_IOV_STRIDE;
1235
1236 while (total_translated < len) {
1237 struct iov_iter iter;
1238 u64 translated;
1239 int ret;
1240
1241 ret = iotlb_translate(vrh, (u64)(uintptr_t)dst,
1242 len - total_translated, &translated,
1243 &ivec, VHOST_MAP_WO);
1244 if (ret == -ENOBUFS)
1245 ret = IOTLB_IOV_STRIDE;
1246 else if (ret < 0)
1247 return ret;
1248
1249 if (vrh->use_va) {
1250 iov_iter_init(&iter, ITER_DEST, ivec.iov.iovec, ret,
1251 translated);
1252 } else {
1253 iov_iter_bvec(&iter, ITER_DEST, ivec.iov.bvec, ret,
1254 translated);
1255 }
1256
1257 ret = copy_to_iter(src, translated, &iter);
1258 if (ret < 0)
1259 return ret;
1260
1261 src += translated;
1262 dst += translated;
1263 total_translated += translated;
1264 }
1265
1266 return total_translated;
1267}
1268
1269static inline int getu16_iotlb(const struct vringh *vrh,
1270 u16 *val, const __virtio16 *p)
1271{
1272 struct iotlb_vec ivec;
1273 union {
1274 struct iovec iovec[1];
1275 struct bio_vec bvec[1];
1276 } iov;
1277 __virtio16 tmp;
1278 int ret;
1279
1280 ivec.iov.iovec = iov.iovec;
1281 ivec.count = 1;
1282
1283 /* Atomic read is needed for getu16 */
1284 ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p),
1285 NULL, &ivec, VHOST_MAP_RO);
1286 if (ret < 0)
1287 return ret;
1288
1289 if (vrh->use_va) {
1290 ret = __get_user(tmp, (__virtio16 __user *)ivec.iov.iovec[0].iov_base);
1291 if (ret)
1292 return ret;
1293 } else {
1294 void *kaddr = kmap_local_page(ivec.iov.bvec[0].bv_page);
1295 void *from = kaddr + ivec.iov.bvec[0].bv_offset;
1296
1297 tmp = READ_ONCE(*(__virtio16 *)from);
1298 kunmap_local(kaddr);
1299 }
1300
1301 *val = vringh16_to_cpu(vrh, tmp);
1302
1303 return 0;
1304}
1305
1306static inline int putu16_iotlb(const struct vringh *vrh,
1307 __virtio16 *p, u16 val)
1308{
1309 struct iotlb_vec ivec;
1310 union {
1311 struct iovec iovec;
1312 struct bio_vec bvec;
1313 } iov;
1314 __virtio16 tmp;
1315 int ret;
1316
1317 ivec.iov.iovec = &iov.iovec;
1318 ivec.count = 1;
1319
1320 /* Atomic write is needed for putu16 */
1321 ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p),
1322 NULL, &ivec, VHOST_MAP_RO);
1323 if (ret < 0)
1324 return ret;
1325
1326 tmp = cpu_to_vringh16(vrh, val);
1327
1328 if (vrh->use_va) {
1329 ret = __put_user(tmp, (__virtio16 __user *)ivec.iov.iovec[0].iov_base);
1330 if (ret)
1331 return ret;
1332 } else {
1333 void *kaddr = kmap_local_page(ivec.iov.bvec[0].bv_page);
1334 void *to = kaddr + ivec.iov.bvec[0].bv_offset;
1335
1336 WRITE_ONCE(*(__virtio16 *)to, tmp);
1337 kunmap_local(kaddr);
1338 }
1339
1340 return 0;
1341}
1342
1343static inline int copydesc_iotlb(const struct vringh *vrh,
1344 void *dst, const void *src, size_t len)
1345{
1346 int ret;
1347
1348 ret = copy_from_iotlb(vrh, dst, (void *)src, len);
1349 if (ret != len)
1350 return -EFAULT;
1351
1352 return 0;
1353}
1354
1355static inline int xfer_from_iotlb(const struct vringh *vrh, void *src,
1356 void *dst, size_t len)
1357{
1358 int ret;
1359
1360 ret = copy_from_iotlb(vrh, dst, src, len);
1361 if (ret != len)
1362 return -EFAULT;
1363
1364 return 0;
1365}
1366
1367static inline int xfer_to_iotlb(const struct vringh *vrh,
1368 void *dst, void *src, size_t len)
1369{
1370 int ret;
1371
1372 ret = copy_to_iotlb(vrh, dst, src, len);
1373 if (ret != len)
1374 return -EFAULT;
1375
1376 return 0;
1377}
1378
1379static inline int putused_iotlb(const struct vringh *vrh,
1380 struct vring_used_elem *dst,
1381 const struct vring_used_elem *src,
1382 unsigned int num)
1383{
1384 int size = num * sizeof(*dst);
1385 int ret;
1386
1387 ret = copy_to_iotlb(vrh, dst, (void *)src, num * sizeof(*dst));
1388 if (ret != size)
1389 return -EFAULT;
1390
1391 return 0;
1392}
1393
1394/**
1395 * vringh_init_iotlb - initialize a vringh for a ring with IOTLB.
1396 * @vrh: the vringh to initialize.
1397 * @features: the feature bits for this ring.
1398 * @num: the number of elements.
1399 * @weak_barriers: true if we only need memory barriers, not I/O.
1400 * @desc: the userspace descriptor pointer.
1401 * @avail: the userspace avail pointer.
1402 * @used: the userspace used pointer.
1403 *
1404 * Returns an error if num is invalid.
1405 */
1406int vringh_init_iotlb(struct vringh *vrh, u64 features,
1407 unsigned int num, bool weak_barriers,
1408 struct vring_desc *desc,
1409 struct vring_avail *avail,
1410 struct vring_used *used)
1411{
1412 vrh->use_va = false;
1413
1414 return vringh_init_kern(vrh, features, num, weak_barriers,
1415 desc, avail, used);
1416}
1417EXPORT_SYMBOL(vringh_init_iotlb);
1418
1419/**
1420 * vringh_init_iotlb_va - initialize a vringh for a ring with IOTLB containing
1421 * user VA.
1422 * @vrh: the vringh to initialize.
1423 * @features: the feature bits for this ring.
1424 * @num: the number of elements.
1425 * @weak_barriers: true if we only need memory barriers, not I/O.
1426 * @desc: the userspace descriptor pointer.
1427 * @avail: the userspace avail pointer.
1428 * @used: the userspace used pointer.
1429 *
1430 * Returns an error if num is invalid.
1431 */
1432int vringh_init_iotlb_va(struct vringh *vrh, u64 features,
1433 unsigned int num, bool weak_barriers,
1434 struct vring_desc *desc,
1435 struct vring_avail *avail,
1436 struct vring_used *used)
1437{
1438 vrh->use_va = true;
1439
1440 return vringh_init_kern(vrh, features, num, weak_barriers,
1441 desc, avail, used);
1442}
1443EXPORT_SYMBOL(vringh_init_iotlb_va);
1444
1445/**
1446 * vringh_set_iotlb - initialize a vringh for a ring with IOTLB.
1447 * @vrh: the vring
1448 * @iotlb: iotlb associated with this vring
1449 * @iotlb_lock: spinlock to synchronize the iotlb accesses
1450 */
1451void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb,
1452 spinlock_t *iotlb_lock)
1453{
1454 vrh->iotlb = iotlb;
1455 vrh->iotlb_lock = iotlb_lock;
1456}
1457EXPORT_SYMBOL(vringh_set_iotlb);
1458
1459/**
1460 * vringh_getdesc_iotlb - get next available descriptor from ring with
1461 * IOTLB.
1462 * @vrh: the kernelspace vring.
1463 * @riov: where to put the readable descriptors (or NULL)
1464 * @wiov: where to put the writable descriptors (or NULL)
1465 * @head: head index we received, for passing to vringh_complete_iotlb().
1466 * @gfp: flags for allocating larger riov/wiov.
1467 *
1468 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
1469 *
1470 * Note that on error return, you can tell the difference between an
1471 * invalid ring and a single invalid descriptor: in the former case,
1472 * *head will be vrh->vring.num. You may be able to ignore an invalid
1473 * descriptor, but there's not much you can do with an invalid ring.
1474 *
1475 * Note that you can reuse riov and wiov with subsequent calls. Content is
1476 * overwritten and memory reallocated if more space is needed.
1477 * When you don't have to use riov and wiov anymore, you should clean up them
1478 * calling vringh_kiov_cleanup() to release the memory, even on error!
1479 */
1480int vringh_getdesc_iotlb(struct vringh *vrh,
1481 struct vringh_kiov *riov,
1482 struct vringh_kiov *wiov,
1483 u16 *head,
1484 gfp_t gfp)
1485{
1486 int err;
1487
1488 err = __vringh_get_head(vrh, getu16_iotlb, &vrh->last_avail_idx);
1489 if (err < 0)
1490 return err;
1491
1492 /* Empty... */
1493 if (err == vrh->vring.num)
1494 return 0;
1495
1496 *head = err;
1497 err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
1498 gfp, copydesc_iotlb);
1499 if (err)
1500 return err;
1501
1502 return 1;
1503}
1504EXPORT_SYMBOL(vringh_getdesc_iotlb);
1505
1506/**
1507 * vringh_iov_pull_iotlb - copy bytes from vring_iov.
1508 * @vrh: the vring.
1509 * @riov: the riov as passed to vringh_getdesc_iotlb() (updated as we consume)
1510 * @dst: the place to copy.
1511 * @len: the maximum length to copy.
1512 *
1513 * Returns the bytes copied <= len or a negative errno.
1514 */
1515ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
1516 struct vringh_kiov *riov,
1517 void *dst, size_t len)
1518{
1519 return vringh_iov_xfer(vrh, riov, dst, len, xfer_from_iotlb);
1520}
1521EXPORT_SYMBOL(vringh_iov_pull_iotlb);
1522
1523/**
1524 * vringh_iov_push_iotlb - copy bytes into vring_iov.
1525 * @vrh: the vring.
1526 * @wiov: the wiov as passed to vringh_getdesc_iotlb() (updated as we consume)
1527 * @src: the place to copy from.
1528 * @len: the maximum length to copy.
1529 *
1530 * Returns the bytes copied <= len or a negative errno.
1531 */
1532ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
1533 struct vringh_kiov *wiov,
1534 const void *src, size_t len)
1535{
1536 return vringh_iov_xfer(vrh, wiov, (void *)src, len, xfer_to_iotlb);
1537}
1538EXPORT_SYMBOL(vringh_iov_push_iotlb);
1539
1540/**
1541 * vringh_abandon_iotlb - we've decided not to handle the descriptor(s).
1542 * @vrh: the vring.
1543 * @num: the number of descriptors to put back (ie. num
1544 * vringh_get_iotlb() to undo).
1545 *
1546 * The next vringh_get_iotlb() will return the old descriptor(s) again.
1547 */
1548void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num)
1549{
1550 /* We only update vring_avail_event(vr) when we want to be notified,
1551 * so we haven't changed that yet.
1552 */
1553 vrh->last_avail_idx -= num;
1554}
1555EXPORT_SYMBOL(vringh_abandon_iotlb);
1556
1557/**
1558 * vringh_complete_iotlb - we've finished with descriptor, publish it.
1559 * @vrh: the vring.
1560 * @head: the head as filled in by vringh_getdesc_iotlb.
1561 * @len: the length of data we have written.
1562 *
1563 * You should check vringh_need_notify_iotlb() after one or more calls
1564 * to this function.
1565 */
1566int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len)
1567{
1568 struct vring_used_elem used;
1569
1570 used.id = cpu_to_vringh32(vrh, head);
1571 used.len = cpu_to_vringh32(vrh, len);
1572
1573 return __vringh_complete(vrh, &used, 1, putu16_iotlb, putused_iotlb);
1574}
1575EXPORT_SYMBOL(vringh_complete_iotlb);
1576
1577/**
1578 * vringh_notify_enable_iotlb - we want to know if something changes.
1579 * @vrh: the vring.
1580 *
1581 * This always enables notifications, but returns false if there are
1582 * now more buffers available in the vring.
1583 */
1584bool vringh_notify_enable_iotlb(struct vringh *vrh)
1585{
1586 return __vringh_notify_enable(vrh, getu16_iotlb, putu16_iotlb);
1587}
1588EXPORT_SYMBOL(vringh_notify_enable_iotlb);
1589
1590/**
1591 * vringh_notify_disable_iotlb - don't tell us if something changes.
1592 * @vrh: the vring.
1593 *
1594 * This is our normal running state: we disable and then only enable when
1595 * we're going to sleep.
1596 */
1597void vringh_notify_disable_iotlb(struct vringh *vrh)
1598{
1599 __vringh_notify_disable(vrh, putu16_iotlb);
1600}
1601EXPORT_SYMBOL(vringh_notify_disable_iotlb);
1602
1603/**
1604 * vringh_need_notify_iotlb - must we tell the other side about used buffers?
1605 * @vrh: the vring we've called vringh_complete_iotlb() on.
1606 *
1607 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
1608 */
1609int vringh_need_notify_iotlb(struct vringh *vrh)
1610{
1611 return __vringh_need_notify(vrh, getu16_iotlb);
1612}
1613EXPORT_SYMBOL(vringh_need_notify_iotlb);
1614
1615#endif
1616
1617MODULE_LICENSE("GPL");
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#include <uapi/linux/virtio_config.h>
17
18static __printf(1,2) __cold void vringh_bad(const char *fmt, ...)
19{
20 static DEFINE_RATELIMIT_STATE(vringh_rs,
21 DEFAULT_RATELIMIT_INTERVAL,
22 DEFAULT_RATELIMIT_BURST);
23 if (__ratelimit(&vringh_rs)) {
24 va_list ap;
25 va_start(ap, fmt);
26 printk(KERN_NOTICE "vringh:");
27 vprintk(fmt, ap);
28 va_end(ap);
29 }
30}
31
32/* Returns vring->num if empty, -ve on error. */
33static inline int __vringh_get_head(const struct vringh *vrh,
34 int (*getu16)(const struct vringh *vrh,
35 u16 *val, const __virtio16 *p),
36 u16 *last_avail_idx)
37{
38 u16 avail_idx, i, head;
39 int err;
40
41 err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx);
42 if (err) {
43 vringh_bad("Failed to access avail idx at %p",
44 &vrh->vring.avail->idx);
45 return err;
46 }
47
48 if (*last_avail_idx == avail_idx)
49 return vrh->vring.num;
50
51 /* Only get avail ring entries after they have been exposed by guest. */
52 virtio_rmb(vrh->weak_barriers);
53
54 i = *last_avail_idx & (vrh->vring.num - 1);
55
56 err = getu16(vrh, &head, &vrh->vring.avail->ring[i]);
57 if (err) {
58 vringh_bad("Failed to read head: idx %d address %p",
59 *last_avail_idx, &vrh->vring.avail->ring[i]);
60 return err;
61 }
62
63 if (head >= vrh->vring.num) {
64 vringh_bad("Guest says index %u > %u is available",
65 head, vrh->vring.num);
66 return -EINVAL;
67 }
68
69 (*last_avail_idx)++;
70 return head;
71}
72
73/* Copy some bytes to/from the iovec. Returns num copied. */
74static inline ssize_t vringh_iov_xfer(struct vringh_kiov *iov,
75 void *ptr, size_t len,
76 int (*xfer)(void *addr, void *ptr,
77 size_t len))
78{
79 int err, done = 0;
80
81 while (len && iov->i < iov->used) {
82 size_t partlen;
83
84 partlen = min(iov->iov[iov->i].iov_len, len);
85 err = xfer(iov->iov[iov->i].iov_base, ptr, partlen);
86 if (err)
87 return err;
88 done += partlen;
89 len -= partlen;
90 ptr += partlen;
91 iov->consumed += partlen;
92 iov->iov[iov->i].iov_len -= partlen;
93 iov->iov[iov->i].iov_base += partlen;
94
95 if (!iov->iov[iov->i].iov_len) {
96 /* Fix up old iov element then increment. */
97 iov->iov[iov->i].iov_len = iov->consumed;
98 iov->iov[iov->i].iov_base -= iov->consumed;
99
100 iov->consumed = 0;
101 iov->i++;
102 }
103 }
104 return done;
105}
106
107/* May reduce *len if range is shorter. */
108static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len,
109 struct vringh_range *range,
110 bool (*getrange)(struct vringh *,
111 u64, struct vringh_range *))
112{
113 if (addr < range->start || addr > range->end_incl) {
114 if (!getrange(vrh, addr, range))
115 return false;
116 }
117 BUG_ON(addr < range->start || addr > range->end_incl);
118
119 /* To end of memory? */
120 if (unlikely(addr + *len == 0)) {
121 if (range->end_incl == -1ULL)
122 return true;
123 goto truncate;
124 }
125
126 /* Otherwise, don't wrap. */
127 if (addr + *len < addr) {
128 vringh_bad("Wrapping descriptor %zu@0x%llx",
129 *len, (unsigned long long)addr);
130 return false;
131 }
132
133 if (unlikely(addr + *len - 1 > range->end_incl))
134 goto truncate;
135 return true;
136
137truncate:
138 *len = range->end_incl + 1 - addr;
139 return true;
140}
141
142static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len,
143 struct vringh_range *range,
144 bool (*getrange)(struct vringh *,
145 u64, struct vringh_range *))
146{
147 return true;
148}
149
150/* No reason for this code to be inline. */
151static int move_to_indirect(const struct vringh *vrh,
152 int *up_next, u16 *i, void *addr,
153 const struct vring_desc *desc,
154 struct vring_desc **descs, int *desc_max)
155{
156 u32 len;
157
158 /* Indirect tables can't have indirect. */
159 if (*up_next != -1) {
160 vringh_bad("Multilevel indirect %u->%u", *up_next, *i);
161 return -EINVAL;
162 }
163
164 len = vringh32_to_cpu(vrh, desc->len);
165 if (unlikely(len % sizeof(struct vring_desc))) {
166 vringh_bad("Strange indirect len %u", desc->len);
167 return -EINVAL;
168 }
169
170 /* We will check this when we follow it! */
171 if (desc->flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT))
172 *up_next = vringh16_to_cpu(vrh, desc->next);
173 else
174 *up_next = -2;
175 *descs = addr;
176 *desc_max = len / sizeof(struct vring_desc);
177
178 /* Now, start at the first indirect. */
179 *i = 0;
180 return 0;
181}
182
183static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
184{
185 struct kvec *new;
186 unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;
187
188 if (new_num < 8)
189 new_num = 8;
190
191 flag = (iov->max_num & VRINGH_IOV_ALLOCATED);
192 if (flag)
193 new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp);
194 else {
195 new = kmalloc_array(new_num, sizeof(struct iovec), gfp);
196 if (new) {
197 memcpy(new, iov->iov,
198 iov->max_num * sizeof(struct iovec));
199 flag = VRINGH_IOV_ALLOCATED;
200 }
201 }
202 if (!new)
203 return -ENOMEM;
204 iov->iov = new;
205 iov->max_num = (new_num | flag);
206 return 0;
207}
208
209static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next,
210 struct vring_desc **descs, int *desc_max)
211{
212 u16 i = *up_next;
213
214 *up_next = -1;
215 *descs = vrh->vring.desc;
216 *desc_max = vrh->vring.num;
217 return i;
218}
219
220static int slow_copy(struct vringh *vrh, void *dst, const void *src,
221 bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
222 struct vringh_range *range,
223 bool (*getrange)(struct vringh *vrh,
224 u64,
225 struct vringh_range *)),
226 bool (*getrange)(struct vringh *vrh,
227 u64 addr,
228 struct vringh_range *r),
229 struct vringh_range *range,
230 int (*copy)(void *dst, const void *src, size_t len))
231{
232 size_t part, len = sizeof(struct vring_desc);
233
234 do {
235 u64 addr;
236 int err;
237
238 part = len;
239 addr = (u64)(unsigned long)src - range->offset;
240
241 if (!rcheck(vrh, addr, &part, range, getrange))
242 return -EINVAL;
243
244 err = copy(dst, src, part);
245 if (err)
246 return err;
247
248 dst += part;
249 src += part;
250 len -= part;
251 } while (len);
252 return 0;
253}
254
255static inline int
256__vringh_iov(struct vringh *vrh, u16 i,
257 struct vringh_kiov *riov,
258 struct vringh_kiov *wiov,
259 bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
260 struct vringh_range *range,
261 bool (*getrange)(struct vringh *, u64,
262 struct vringh_range *)),
263 bool (*getrange)(struct vringh *, u64, struct vringh_range *),
264 gfp_t gfp,
265 int (*copy)(void *dst, const void *src, size_t len))
266{
267 int err, count = 0, up_next, desc_max;
268 struct vring_desc desc, *descs;
269 struct vringh_range range = { -1ULL, 0 }, slowrange;
270 bool slow = false;
271
272 /* We start traversing vring's descriptor table. */
273 descs = vrh->vring.desc;
274 desc_max = vrh->vring.num;
275 up_next = -1;
276
277 if (riov)
278 riov->i = riov->used = 0;
279 else if (wiov)
280 wiov->i = wiov->used = 0;
281 else
282 /* You must want something! */
283 BUG();
284
285 for (;;) {
286 void *addr;
287 struct vringh_kiov *iov;
288 size_t len;
289
290 if (unlikely(slow))
291 err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange,
292 &slowrange, copy);
293 else
294 err = copy(&desc, &descs[i], sizeof(desc));
295 if (unlikely(err))
296 goto fail;
297
298 if (unlikely(desc.flags &
299 cpu_to_vringh16(vrh, VRING_DESC_F_INDIRECT))) {
300 u64 a = vringh64_to_cpu(vrh, desc.addr);
301
302 /* Make sure it's OK, and get offset. */
303 len = vringh32_to_cpu(vrh, desc.len);
304 if (!rcheck(vrh, a, &len, &range, getrange)) {
305 err = -EINVAL;
306 goto fail;
307 }
308
309 if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
310 slow = true;
311 /* We need to save this range to use offset */
312 slowrange = range;
313 }
314
315 addr = (void *)(long)(a + range.offset);
316 err = move_to_indirect(vrh, &up_next, &i, addr, &desc,
317 &descs, &desc_max);
318 if (err)
319 goto fail;
320 continue;
321 }
322
323 if (count++ == vrh->vring.num) {
324 vringh_bad("Descriptor loop in %p", descs);
325 err = -ELOOP;
326 goto fail;
327 }
328
329 if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_WRITE))
330 iov = wiov;
331 else {
332 iov = riov;
333 if (unlikely(wiov && wiov->i)) {
334 vringh_bad("Readable desc %p after writable",
335 &descs[i]);
336 err = -EINVAL;
337 goto fail;
338 }
339 }
340
341 if (!iov) {
342 vringh_bad("Unexpected %s desc",
343 !wiov ? "writable" : "readable");
344 err = -EPROTO;
345 goto fail;
346 }
347
348 again:
349 /* Make sure it's OK, and get offset. */
350 len = vringh32_to_cpu(vrh, desc.len);
351 if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range,
352 getrange)) {
353 err = -EINVAL;
354 goto fail;
355 }
356 addr = (void *)(unsigned long)(vringh64_to_cpu(vrh, desc.addr) +
357 range.offset);
358
359 if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) {
360 err = resize_iovec(iov, gfp);
361 if (err)
362 goto fail;
363 }
364
365 iov->iov[iov->used].iov_base = addr;
366 iov->iov[iov->used].iov_len = len;
367 iov->used++;
368
369 if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
370 desc.len = cpu_to_vringh32(vrh,
371 vringh32_to_cpu(vrh, desc.len) - len);
372 desc.addr = cpu_to_vringh64(vrh,
373 vringh64_to_cpu(vrh, desc.addr) + len);
374 goto again;
375 }
376
377 if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) {
378 i = vringh16_to_cpu(vrh, desc.next);
379 } else {
380 /* Just in case we need to finish traversing above. */
381 if (unlikely(up_next > 0)) {
382 i = return_from_indirect(vrh, &up_next,
383 &descs, &desc_max);
384 slow = false;
385 } else
386 break;
387 }
388
389 if (i >= desc_max) {
390 vringh_bad("Chained index %u > %u", i, desc_max);
391 err = -EINVAL;
392 goto fail;
393 }
394 }
395
396 return 0;
397
398fail:
399 return err;
400}
401
402static inline int __vringh_complete(struct vringh *vrh,
403 const struct vring_used_elem *used,
404 unsigned int num_used,
405 int (*putu16)(const struct vringh *vrh,
406 __virtio16 *p, u16 val),
407 int (*putused)(struct vring_used_elem *dst,
408 const struct vring_used_elem
409 *src, unsigned num))
410{
411 struct vring_used *used_ring;
412 int err;
413 u16 used_idx, off;
414
415 used_ring = vrh->vring.used;
416 used_idx = vrh->last_used_idx + vrh->completed;
417
418 off = used_idx % vrh->vring.num;
419
420 /* Compiler knows num_used == 1 sometimes, hence extra check */
421 if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) {
422 u16 part = vrh->vring.num - off;
423 err = putused(&used_ring->ring[off], used, part);
424 if (!err)
425 err = putused(&used_ring->ring[0], used + part,
426 num_used - part);
427 } else
428 err = putused(&used_ring->ring[off], used, num_used);
429
430 if (err) {
431 vringh_bad("Failed to write %u used entries %u at %p",
432 num_used, off, &used_ring->ring[off]);
433 return err;
434 }
435
436 /* Make sure buffer is written before we update index. */
437 virtio_wmb(vrh->weak_barriers);
438
439 err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used);
440 if (err) {
441 vringh_bad("Failed to update used index at %p",
442 &vrh->vring.used->idx);
443 return err;
444 }
445
446 vrh->completed += num_used;
447 return 0;
448}
449
450
451static inline int __vringh_need_notify(struct vringh *vrh,
452 int (*getu16)(const struct vringh *vrh,
453 u16 *val,
454 const __virtio16 *p))
455{
456 bool notify;
457 u16 used_event;
458 int err;
459
460 /* Flush out used index update. This is paired with the
461 * barrier that the Guest executes when enabling
462 * interrupts. */
463 virtio_mb(vrh->weak_barriers);
464
465 /* Old-style, without event indices. */
466 if (!vrh->event_indices) {
467 u16 flags;
468 err = getu16(vrh, &flags, &vrh->vring.avail->flags);
469 if (err) {
470 vringh_bad("Failed to get flags at %p",
471 &vrh->vring.avail->flags);
472 return err;
473 }
474 return (!(flags & VRING_AVAIL_F_NO_INTERRUPT));
475 }
476
477 /* Modern: we know when other side wants to know. */
478 err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring));
479 if (err) {
480 vringh_bad("Failed to get used event idx at %p",
481 &vring_used_event(&vrh->vring));
482 return err;
483 }
484
485 /* Just in case we added so many that we wrap. */
486 if (unlikely(vrh->completed > 0xffff))
487 notify = true;
488 else
489 notify = vring_need_event(used_event,
490 vrh->last_used_idx + vrh->completed,
491 vrh->last_used_idx);
492
493 vrh->last_used_idx += vrh->completed;
494 vrh->completed = 0;
495 return notify;
496}
497
498static inline bool __vringh_notify_enable(struct vringh *vrh,
499 int (*getu16)(const struct vringh *vrh,
500 u16 *val, const __virtio16 *p),
501 int (*putu16)(const struct vringh *vrh,
502 __virtio16 *p, u16 val))
503{
504 u16 avail;
505
506 if (!vrh->event_indices) {
507 /* Old-school; update flags. */
508 if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) {
509 vringh_bad("Clearing used flags %p",
510 &vrh->vring.used->flags);
511 return true;
512 }
513 } else {
514 if (putu16(vrh, &vring_avail_event(&vrh->vring),
515 vrh->last_avail_idx) != 0) {
516 vringh_bad("Updating avail event index %p",
517 &vring_avail_event(&vrh->vring));
518 return true;
519 }
520 }
521
522 /* They could have slipped one in as we were doing that: make
523 * sure it's written, then check again. */
524 virtio_mb(vrh->weak_barriers);
525
526 if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) {
527 vringh_bad("Failed to check avail idx at %p",
528 &vrh->vring.avail->idx);
529 return true;
530 }
531
532 /* This is unlikely, so we just leave notifications enabled
533 * (if we're using event_indices, we'll only get one
534 * notification anyway). */
535 return avail == vrh->last_avail_idx;
536}
537
538static inline void __vringh_notify_disable(struct vringh *vrh,
539 int (*putu16)(const struct vringh *vrh,
540 __virtio16 *p, u16 val))
541{
542 if (!vrh->event_indices) {
543 /* Old-school; update flags. */
544 if (putu16(vrh, &vrh->vring.used->flags,
545 VRING_USED_F_NO_NOTIFY)) {
546 vringh_bad("Setting used flags %p",
547 &vrh->vring.used->flags);
548 }
549 }
550}
551
552/* Userspace access helpers: in this case, addresses are really userspace. */
553static inline int getu16_user(const struct vringh *vrh, u16 *val, const __virtio16 *p)
554{
555 __virtio16 v = 0;
556 int rc = get_user(v, (__force __virtio16 __user *)p);
557 *val = vringh16_to_cpu(vrh, v);
558 return rc;
559}
560
561static inline int putu16_user(const struct vringh *vrh, __virtio16 *p, u16 val)
562{
563 __virtio16 v = cpu_to_vringh16(vrh, val);
564 return put_user(v, (__force __virtio16 __user *)p);
565}
566
567static inline int copydesc_user(void *dst, const void *src, size_t len)
568{
569 return copy_from_user(dst, (__force void __user *)src, len) ?
570 -EFAULT : 0;
571}
572
573static inline int putused_user(struct vring_used_elem *dst,
574 const struct vring_used_elem *src,
575 unsigned int num)
576{
577 return copy_to_user((__force void __user *)dst, src,
578 sizeof(*dst) * num) ? -EFAULT : 0;
579}
580
581static inline int xfer_from_user(void *src, void *dst, size_t len)
582{
583 return copy_from_user(dst, (__force void __user *)src, len) ?
584 -EFAULT : 0;
585}
586
587static inline int xfer_to_user(void *dst, void *src, size_t len)
588{
589 return copy_to_user((__force void __user *)dst, src, len) ?
590 -EFAULT : 0;
591}
592
593/**
594 * vringh_init_user - initialize a vringh for a userspace vring.
595 * @vrh: the vringh to initialize.
596 * @features: the feature bits for this ring.
597 * @num: the number of elements.
598 * @weak_barriers: true if we only need memory barriers, not I/O.
599 * @desc: the userpace descriptor pointer.
600 * @avail: the userpace avail pointer.
601 * @used: the userpace used pointer.
602 *
603 * Returns an error if num is invalid: you should check pointers
604 * yourself!
605 */
606int vringh_init_user(struct vringh *vrh, u64 features,
607 unsigned int num, bool weak_barriers,
608 struct vring_desc __user *desc,
609 struct vring_avail __user *avail,
610 struct vring_used __user *used)
611{
612 /* Sane power of 2 please! */
613 if (!num || num > 0xffff || (num & (num - 1))) {
614 vringh_bad("Bad ring size %u", num);
615 return -EINVAL;
616 }
617
618 vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
619 vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
620 vrh->weak_barriers = weak_barriers;
621 vrh->completed = 0;
622 vrh->last_avail_idx = 0;
623 vrh->last_used_idx = 0;
624 vrh->vring.num = num;
625 /* vring expects kernel addresses, but only used via accessors. */
626 vrh->vring.desc = (__force struct vring_desc *)desc;
627 vrh->vring.avail = (__force struct vring_avail *)avail;
628 vrh->vring.used = (__force struct vring_used *)used;
629 return 0;
630}
631EXPORT_SYMBOL(vringh_init_user);
632
633/**
634 * vringh_getdesc_user - get next available descriptor from userspace ring.
635 * @vrh: the userspace vring.
636 * @riov: where to put the readable descriptors (or NULL)
637 * @wiov: where to put the writable descriptors (or NULL)
638 * @getrange: function to call to check ranges.
639 * @head: head index we received, for passing to vringh_complete_user().
640 *
641 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
642 *
643 * Note that on error return, you can tell the difference between an
644 * invalid ring and a single invalid descriptor: in the former case,
645 * *head will be vrh->vring.num. You may be able to ignore an invalid
646 * descriptor, but there's not much you can do with an invalid ring.
647 *
648 * Note that you may need to clean up riov and wiov, even on error!
649 */
650int vringh_getdesc_user(struct vringh *vrh,
651 struct vringh_iov *riov,
652 struct vringh_iov *wiov,
653 bool (*getrange)(struct vringh *vrh,
654 u64 addr, struct vringh_range *r),
655 u16 *head)
656{
657 int err;
658
659 *head = vrh->vring.num;
660 err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx);
661 if (err < 0)
662 return err;
663
664 /* Empty... */
665 if (err == vrh->vring.num)
666 return 0;
667
668 /* We need the layouts to be the identical for this to work */
669 BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov));
670 BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) !=
671 offsetof(struct vringh_iov, iov));
672 BUILD_BUG_ON(offsetof(struct vringh_kiov, i) !=
673 offsetof(struct vringh_iov, i));
674 BUILD_BUG_ON(offsetof(struct vringh_kiov, used) !=
675 offsetof(struct vringh_iov, used));
676 BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) !=
677 offsetof(struct vringh_iov, max_num));
678 BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
679 BUILD_BUG_ON(offsetof(struct iovec, iov_base) !=
680 offsetof(struct kvec, iov_base));
681 BUILD_BUG_ON(offsetof(struct iovec, iov_len) !=
682 offsetof(struct kvec, iov_len));
683 BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base)
684 != sizeof(((struct kvec *)NULL)->iov_base));
685 BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len)
686 != sizeof(((struct kvec *)NULL)->iov_len));
687
688 *head = err;
689 err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
690 (struct vringh_kiov *)wiov,
691 range_check, getrange, GFP_KERNEL, copydesc_user);
692 if (err)
693 return err;
694
695 return 1;
696}
697EXPORT_SYMBOL(vringh_getdesc_user);
698
699/**
700 * vringh_iov_pull_user - copy bytes from vring_iov.
701 * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume)
702 * @dst: the place to copy.
703 * @len: the maximum length to copy.
704 *
705 * Returns the bytes copied <= len or a negative errno.
706 */
707ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len)
708{
709 return vringh_iov_xfer((struct vringh_kiov *)riov,
710 dst, len, xfer_from_user);
711}
712EXPORT_SYMBOL(vringh_iov_pull_user);
713
714/**
715 * vringh_iov_push_user - copy bytes into vring_iov.
716 * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume)
717 * @dst: the place to copy.
718 * @len: the maximum length to copy.
719 *
720 * Returns the bytes copied <= len or a negative errno.
721 */
722ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
723 const void *src, size_t len)
724{
725 return vringh_iov_xfer((struct vringh_kiov *)wiov,
726 (void *)src, len, xfer_to_user);
727}
728EXPORT_SYMBOL(vringh_iov_push_user);
729
730/**
731 * vringh_abandon_user - we've decided not to handle the descriptor(s).
732 * @vrh: the vring.
733 * @num: the number of descriptors to put back (ie. num
734 * vringh_get_user() to undo).
735 *
736 * The next vringh_get_user() will return the old descriptor(s) again.
737 */
738void vringh_abandon_user(struct vringh *vrh, unsigned int num)
739{
740 /* We only update vring_avail_event(vr) when we want to be notified,
741 * so we haven't changed that yet. */
742 vrh->last_avail_idx -= num;
743}
744EXPORT_SYMBOL(vringh_abandon_user);
745
746/**
747 * vringh_complete_user - we've finished with descriptor, publish it.
748 * @vrh: the vring.
749 * @head: the head as filled in by vringh_getdesc_user.
750 * @len: the length of data we have written.
751 *
752 * You should check vringh_need_notify_user() after one or more calls
753 * to this function.
754 */
755int vringh_complete_user(struct vringh *vrh, u16 head, u32 len)
756{
757 struct vring_used_elem used;
758
759 used.id = cpu_to_vringh32(vrh, head);
760 used.len = cpu_to_vringh32(vrh, len);
761 return __vringh_complete(vrh, &used, 1, putu16_user, putused_user);
762}
763EXPORT_SYMBOL(vringh_complete_user);
764
765/**
766 * vringh_complete_multi_user - we've finished with many descriptors.
767 * @vrh: the vring.
768 * @used: the head, length pairs.
769 * @num_used: the number of used elements.
770 *
771 * You should check vringh_need_notify_user() after one or more calls
772 * to this function.
773 */
774int vringh_complete_multi_user(struct vringh *vrh,
775 const struct vring_used_elem used[],
776 unsigned num_used)
777{
778 return __vringh_complete(vrh, used, num_used,
779 putu16_user, putused_user);
780}
781EXPORT_SYMBOL(vringh_complete_multi_user);
782
783/**
784 * vringh_notify_enable_user - we want to know if something changes.
785 * @vrh: the vring.
786 *
787 * This always enables notifications, but returns false if there are
788 * now more buffers available in the vring.
789 */
790bool vringh_notify_enable_user(struct vringh *vrh)
791{
792 return __vringh_notify_enable(vrh, getu16_user, putu16_user);
793}
794EXPORT_SYMBOL(vringh_notify_enable_user);
795
796/**
797 * vringh_notify_disable_user - don't tell us if something changes.
798 * @vrh: the vring.
799 *
800 * This is our normal running state: we disable and then only enable when
801 * we're going to sleep.
802 */
803void vringh_notify_disable_user(struct vringh *vrh)
804{
805 __vringh_notify_disable(vrh, putu16_user);
806}
807EXPORT_SYMBOL(vringh_notify_disable_user);
808
809/**
810 * vringh_need_notify_user - must we tell the other side about used buffers?
811 * @vrh: the vring we've called vringh_complete_user() on.
812 *
813 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
814 */
815int vringh_need_notify_user(struct vringh *vrh)
816{
817 return __vringh_need_notify(vrh, getu16_user);
818}
819EXPORT_SYMBOL(vringh_need_notify_user);
820
821/* Kernelspace access helpers. */
822static inline int getu16_kern(const struct vringh *vrh,
823 u16 *val, const __virtio16 *p)
824{
825 *val = vringh16_to_cpu(vrh, READ_ONCE(*p));
826 return 0;
827}
828
829static inline int putu16_kern(const struct vringh *vrh, __virtio16 *p, u16 val)
830{
831 WRITE_ONCE(*p, cpu_to_vringh16(vrh, val));
832 return 0;
833}
834
835static inline int copydesc_kern(void *dst, const void *src, size_t len)
836{
837 memcpy(dst, src, len);
838 return 0;
839}
840
841static inline int putused_kern(struct vring_used_elem *dst,
842 const struct vring_used_elem *src,
843 unsigned int num)
844{
845 memcpy(dst, src, num * sizeof(*dst));
846 return 0;
847}
848
849static inline int xfer_kern(void *src, void *dst, size_t len)
850{
851 memcpy(dst, src, len);
852 return 0;
853}
854
855static inline int kern_xfer(void *dst, void *src, size_t len)
856{
857 memcpy(dst, src, len);
858 return 0;
859}
860
861/**
862 * vringh_init_kern - initialize a vringh for a kernelspace vring.
863 * @vrh: the vringh to initialize.
864 * @features: the feature bits for this ring.
865 * @num: the number of elements.
866 * @weak_barriers: true if we only need memory barriers, not I/O.
867 * @desc: the userpace descriptor pointer.
868 * @avail: the userpace avail pointer.
869 * @used: the userpace used pointer.
870 *
871 * Returns an error if num is invalid.
872 */
873int vringh_init_kern(struct vringh *vrh, u64 features,
874 unsigned int num, bool weak_barriers,
875 struct vring_desc *desc,
876 struct vring_avail *avail,
877 struct vring_used *used)
878{
879 /* Sane power of 2 please! */
880 if (!num || num > 0xffff || (num & (num - 1))) {
881 vringh_bad("Bad ring size %u", num);
882 return -EINVAL;
883 }
884
885 vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
886 vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
887 vrh->weak_barriers = weak_barriers;
888 vrh->completed = 0;
889 vrh->last_avail_idx = 0;
890 vrh->last_used_idx = 0;
891 vrh->vring.num = num;
892 vrh->vring.desc = desc;
893 vrh->vring.avail = avail;
894 vrh->vring.used = used;
895 return 0;
896}
897EXPORT_SYMBOL(vringh_init_kern);
898
899/**
900 * vringh_getdesc_kern - get next available descriptor from kernelspace ring.
901 * @vrh: the kernelspace vring.
902 * @riov: where to put the readable descriptors (or NULL)
903 * @wiov: where to put the writable descriptors (or NULL)
904 * @head: head index we received, for passing to vringh_complete_kern().
905 * @gfp: flags for allocating larger riov/wiov.
906 *
907 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
908 *
909 * Note that on error return, you can tell the difference between an
910 * invalid ring and a single invalid descriptor: in the former case,
911 * *head will be vrh->vring.num. You may be able to ignore an invalid
912 * descriptor, but there's not much you can do with an invalid ring.
913 *
914 * Note that you may need to clean up riov and wiov, even on error!
915 */
916int vringh_getdesc_kern(struct vringh *vrh,
917 struct vringh_kiov *riov,
918 struct vringh_kiov *wiov,
919 u16 *head,
920 gfp_t gfp)
921{
922 int err;
923
924 err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx);
925 if (err < 0)
926 return err;
927
928 /* Empty... */
929 if (err == vrh->vring.num)
930 return 0;
931
932 *head = err;
933 err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
934 gfp, copydesc_kern);
935 if (err)
936 return err;
937
938 return 1;
939}
940EXPORT_SYMBOL(vringh_getdesc_kern);
941
942/**
943 * vringh_iov_pull_kern - copy bytes from vring_iov.
944 * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume)
945 * @dst: the place to copy.
946 * @len: the maximum length to copy.
947 *
948 * Returns the bytes copied <= len or a negative errno.
949 */
950ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len)
951{
952 return vringh_iov_xfer(riov, dst, len, xfer_kern);
953}
954EXPORT_SYMBOL(vringh_iov_pull_kern);
955
956/**
957 * vringh_iov_push_kern - copy bytes into vring_iov.
958 * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume)
959 * @dst: the place to copy.
960 * @len: the maximum length to copy.
961 *
962 * Returns the bytes copied <= len or a negative errno.
963 */
964ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
965 const void *src, size_t len)
966{
967 return vringh_iov_xfer(wiov, (void *)src, len, kern_xfer);
968}
969EXPORT_SYMBOL(vringh_iov_push_kern);
970
971/**
972 * vringh_abandon_kern - we've decided not to handle the descriptor(s).
973 * @vrh: the vring.
974 * @num: the number of descriptors to put back (ie. num
975 * vringh_get_kern() to undo).
976 *
977 * The next vringh_get_kern() will return the old descriptor(s) again.
978 */
979void vringh_abandon_kern(struct vringh *vrh, unsigned int num)
980{
981 /* We only update vring_avail_event(vr) when we want to be notified,
982 * so we haven't changed that yet. */
983 vrh->last_avail_idx -= num;
984}
985EXPORT_SYMBOL(vringh_abandon_kern);
986
987/**
988 * vringh_complete_kern - we've finished with descriptor, publish it.
989 * @vrh: the vring.
990 * @head: the head as filled in by vringh_getdesc_kern.
991 * @len: the length of data we have written.
992 *
993 * You should check vringh_need_notify_kern() after one or more calls
994 * to this function.
995 */
996int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len)
997{
998 struct vring_used_elem used;
999
1000 used.id = cpu_to_vringh32(vrh, head);
1001 used.len = cpu_to_vringh32(vrh, len);
1002
1003 return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern);
1004}
1005EXPORT_SYMBOL(vringh_complete_kern);
1006
1007/**
1008 * vringh_notify_enable_kern - we want to know if something changes.
1009 * @vrh: the vring.
1010 *
1011 * This always enables notifications, but returns false if there are
1012 * now more buffers available in the vring.
1013 */
1014bool vringh_notify_enable_kern(struct vringh *vrh)
1015{
1016 return __vringh_notify_enable(vrh, getu16_kern, putu16_kern);
1017}
1018EXPORT_SYMBOL(vringh_notify_enable_kern);
1019
1020/**
1021 * vringh_notify_disable_kern - don't tell us if something changes.
1022 * @vrh: the vring.
1023 *
1024 * This is our normal running state: we disable and then only enable when
1025 * we're going to sleep.
1026 */
1027void vringh_notify_disable_kern(struct vringh *vrh)
1028{
1029 __vringh_notify_disable(vrh, putu16_kern);
1030}
1031EXPORT_SYMBOL(vringh_notify_disable_kern);
1032
1033/**
1034 * vringh_need_notify_kern - must we tell the other side about used buffers?
1035 * @vrh: the vring we've called vringh_complete_kern() on.
1036 *
1037 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
1038 */
1039int vringh_need_notify_kern(struct vringh *vrh)
1040{
1041 return __vringh_need_notify(vrh, getu16_kern);
1042}
1043EXPORT_SYMBOL(vringh_need_notify_kern);
1044
1045MODULE_LICENSE("GPL");