1f87d0fbbSRusty Russell /* 2f87d0fbbSRusty Russell * Helpers for the host side of a virtio ring. 3f87d0fbbSRusty Russell * 4f87d0fbbSRusty Russell * Since these may be in userspace, we use (inline) accessors. 5f87d0fbbSRusty Russell */ 6f87d0fbbSRusty Russell #include <linux/vringh.h> 7f87d0fbbSRusty Russell #include <linux/virtio_ring.h> 8f87d0fbbSRusty Russell #include <linux/kernel.h> 9f87d0fbbSRusty Russell #include <linux/ratelimit.h> 10f87d0fbbSRusty Russell #include <linux/uaccess.h> 11f87d0fbbSRusty Russell #include <linux/slab.h> 12f87d0fbbSRusty Russell #include <linux/export.h> 13f87d0fbbSRusty Russell 14f87d0fbbSRusty Russell static __printf(1,2) __cold void vringh_bad(const char *fmt, ...) 15f87d0fbbSRusty Russell { 16f87d0fbbSRusty Russell static DEFINE_RATELIMIT_STATE(vringh_rs, 17f87d0fbbSRusty Russell DEFAULT_RATELIMIT_INTERVAL, 18f87d0fbbSRusty Russell DEFAULT_RATELIMIT_BURST); 19f87d0fbbSRusty Russell if (__ratelimit(&vringh_rs)) { 20f87d0fbbSRusty Russell va_list ap; 21f87d0fbbSRusty Russell va_start(ap, fmt); 22f87d0fbbSRusty Russell printk(KERN_NOTICE "vringh:"); 23f87d0fbbSRusty Russell vprintk(fmt, ap); 24f87d0fbbSRusty Russell va_end(ap); 25f87d0fbbSRusty Russell } 26f87d0fbbSRusty Russell } 27f87d0fbbSRusty Russell 28f87d0fbbSRusty Russell /* Returns vring->num if empty, -ve on error. */ 29f87d0fbbSRusty Russell static inline int __vringh_get_head(const struct vringh *vrh, 30f87d0fbbSRusty Russell int (*getu16)(u16 *val, const u16 *p), 31f87d0fbbSRusty Russell u16 *last_avail_idx) 32f87d0fbbSRusty Russell { 33f87d0fbbSRusty Russell u16 avail_idx, i, head; 34f87d0fbbSRusty Russell int err; 35f87d0fbbSRusty Russell 36f87d0fbbSRusty Russell err = getu16(&avail_idx, &vrh->vring.avail->idx); 37f87d0fbbSRusty Russell if (err) { 38f87d0fbbSRusty Russell vringh_bad("Failed to access avail idx at %p", 39f87d0fbbSRusty Russell &vrh->vring.avail->idx); 40f87d0fbbSRusty Russell return err; 41f87d0fbbSRusty Russell } 42f87d0fbbSRusty Russell 43f87d0fbbSRusty Russell if (*last_avail_idx == avail_idx) 44f87d0fbbSRusty Russell return vrh->vring.num; 45f87d0fbbSRusty Russell 46f87d0fbbSRusty Russell /* Only get avail ring entries after they have been exposed by guest. */ 47f87d0fbbSRusty Russell virtio_rmb(vrh->weak_barriers); 48f87d0fbbSRusty Russell 49f87d0fbbSRusty Russell i = *last_avail_idx & (vrh->vring.num - 1); 50f87d0fbbSRusty Russell 51f87d0fbbSRusty Russell err = getu16(&head, &vrh->vring.avail->ring[i]); 52f87d0fbbSRusty Russell if (err) { 53f87d0fbbSRusty Russell vringh_bad("Failed to read head: idx %d address %p", 54f87d0fbbSRusty Russell *last_avail_idx, &vrh->vring.avail->ring[i]); 55f87d0fbbSRusty Russell return err; 56f87d0fbbSRusty Russell } 57f87d0fbbSRusty Russell 58f87d0fbbSRusty Russell if (head >= vrh->vring.num) { 59f87d0fbbSRusty Russell vringh_bad("Guest says index %u > %u is available", 60f87d0fbbSRusty Russell head, vrh->vring.num); 61f87d0fbbSRusty Russell return -EINVAL; 62f87d0fbbSRusty Russell } 63f87d0fbbSRusty Russell 64f87d0fbbSRusty Russell (*last_avail_idx)++; 65f87d0fbbSRusty Russell return head; 66f87d0fbbSRusty Russell } 67f87d0fbbSRusty Russell 68f87d0fbbSRusty Russell /* Copy some bytes to/from the iovec. Returns num copied. */ 69f87d0fbbSRusty Russell static inline ssize_t vringh_iov_xfer(struct vringh_kiov *iov, 70f87d0fbbSRusty Russell void *ptr, size_t len, 71f87d0fbbSRusty Russell int (*xfer)(void *addr, void *ptr, 72f87d0fbbSRusty Russell size_t len)) 73f87d0fbbSRusty Russell { 74f87d0fbbSRusty Russell int err, done = 0; 75f87d0fbbSRusty Russell 76f87d0fbbSRusty Russell while (len && iov->i < iov->used) { 77f87d0fbbSRusty Russell size_t partlen; 78f87d0fbbSRusty Russell 79f87d0fbbSRusty Russell partlen = min(iov->iov[iov->i].iov_len, len); 80f87d0fbbSRusty Russell err = xfer(iov->iov[iov->i].iov_base, ptr, partlen); 81f87d0fbbSRusty Russell if (err) 82f87d0fbbSRusty Russell return err; 83f87d0fbbSRusty Russell done += partlen; 84f87d0fbbSRusty Russell len -= partlen; 85f87d0fbbSRusty Russell ptr += partlen; 86f87d0fbbSRusty Russell iov->consumed += partlen; 87f87d0fbbSRusty Russell iov->iov[iov->i].iov_len -= partlen; 88f87d0fbbSRusty Russell iov->iov[iov->i].iov_base += partlen; 89f87d0fbbSRusty Russell 90f87d0fbbSRusty Russell if (!iov->iov[iov->i].iov_len) { 91f87d0fbbSRusty Russell /* Fix up old iov element then increment. */ 92f87d0fbbSRusty Russell iov->iov[iov->i].iov_len = iov->consumed; 93f87d0fbbSRusty Russell iov->iov[iov->i].iov_base -= iov->consumed; 94f87d0fbbSRusty Russell 95f87d0fbbSRusty Russell iov->consumed = 0; 96f87d0fbbSRusty Russell iov->i++; 97f87d0fbbSRusty Russell } 98f87d0fbbSRusty Russell } 99f87d0fbbSRusty Russell return done; 100f87d0fbbSRusty Russell } 101f87d0fbbSRusty Russell 102f87d0fbbSRusty Russell /* May reduce *len if range is shorter. */ 103f87d0fbbSRusty Russell static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len, 104f87d0fbbSRusty Russell struct vringh_range *range, 105f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, 106f87d0fbbSRusty Russell u64, struct vringh_range *)) 107f87d0fbbSRusty Russell { 108f87d0fbbSRusty Russell if (addr < range->start || addr > range->end_incl) { 109f87d0fbbSRusty Russell if (!getrange(vrh, addr, range)) 110f87d0fbbSRusty Russell return false; 111f87d0fbbSRusty Russell } 112f87d0fbbSRusty Russell BUG_ON(addr < range->start || addr > range->end_incl); 113f87d0fbbSRusty Russell 114f87d0fbbSRusty Russell /* To end of memory? */ 115f87d0fbbSRusty Russell if (unlikely(addr + *len == 0)) { 116f87d0fbbSRusty Russell if (range->end_incl == -1ULL) 117f87d0fbbSRusty Russell return true; 118f87d0fbbSRusty Russell goto truncate; 119f87d0fbbSRusty Russell } 120f87d0fbbSRusty Russell 121f87d0fbbSRusty Russell /* Otherwise, don't wrap. */ 122f87d0fbbSRusty Russell if (addr + *len < addr) { 123f87d0fbbSRusty Russell vringh_bad("Wrapping descriptor %zu@0x%llx", 124f87d0fbbSRusty Russell *len, (unsigned long long)addr); 125f87d0fbbSRusty Russell return false; 126f87d0fbbSRusty Russell } 127f87d0fbbSRusty Russell 128f87d0fbbSRusty Russell if (unlikely(addr + *len - 1 > range->end_incl)) 129f87d0fbbSRusty Russell goto truncate; 130f87d0fbbSRusty Russell return true; 131f87d0fbbSRusty Russell 132f87d0fbbSRusty Russell truncate: 133f87d0fbbSRusty Russell *len = range->end_incl + 1 - addr; 134f87d0fbbSRusty Russell return true; 135f87d0fbbSRusty Russell } 136f87d0fbbSRusty Russell 137f87d0fbbSRusty Russell static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len, 138f87d0fbbSRusty Russell struct vringh_range *range, 139f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, 140f87d0fbbSRusty Russell u64, struct vringh_range *)) 141f87d0fbbSRusty Russell { 142f87d0fbbSRusty Russell return true; 143f87d0fbbSRusty Russell } 144f87d0fbbSRusty Russell 145f87d0fbbSRusty Russell /* No reason for this code to be inline. */ 146f87d0fbbSRusty Russell static int move_to_indirect(int *up_next, u16 *i, void *addr, 147f87d0fbbSRusty Russell const struct vring_desc *desc, 148f87d0fbbSRusty Russell struct vring_desc **descs, int *desc_max) 149f87d0fbbSRusty Russell { 150f87d0fbbSRusty Russell /* Indirect tables can't have indirect. */ 151f87d0fbbSRusty Russell if (*up_next != -1) { 152f87d0fbbSRusty Russell vringh_bad("Multilevel indirect %u->%u", *up_next, *i); 153f87d0fbbSRusty Russell return -EINVAL; 154f87d0fbbSRusty Russell } 155f87d0fbbSRusty Russell 156f87d0fbbSRusty Russell if (unlikely(desc->len % sizeof(struct vring_desc))) { 157f87d0fbbSRusty Russell vringh_bad("Strange indirect len %u", desc->len); 158f87d0fbbSRusty Russell return -EINVAL; 159f87d0fbbSRusty Russell } 160f87d0fbbSRusty Russell 161f87d0fbbSRusty Russell /* We will check this when we follow it! */ 162f87d0fbbSRusty Russell if (desc->flags & VRING_DESC_F_NEXT) 163f87d0fbbSRusty Russell *up_next = desc->next; 164f87d0fbbSRusty Russell else 165f87d0fbbSRusty Russell *up_next = -2; 166f87d0fbbSRusty Russell *descs = addr; 167f87d0fbbSRusty Russell *desc_max = desc->len / sizeof(struct vring_desc); 168f87d0fbbSRusty Russell 169f87d0fbbSRusty Russell /* Now, start at the first indirect. */ 170f87d0fbbSRusty Russell *i = 0; 171f87d0fbbSRusty Russell return 0; 172f87d0fbbSRusty Russell } 173f87d0fbbSRusty Russell 174f87d0fbbSRusty Russell static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp) 175f87d0fbbSRusty Russell { 176f87d0fbbSRusty Russell struct kvec *new; 177f87d0fbbSRusty Russell unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2; 178f87d0fbbSRusty Russell 179f87d0fbbSRusty Russell if (new_num < 8) 180f87d0fbbSRusty Russell new_num = 8; 181f87d0fbbSRusty Russell 182f87d0fbbSRusty Russell flag = (iov->max_num & VRINGH_IOV_ALLOCATED); 183f87d0fbbSRusty Russell if (flag) 184f87d0fbbSRusty Russell new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp); 185f87d0fbbSRusty Russell else { 186f87d0fbbSRusty Russell new = kmalloc(new_num * sizeof(struct iovec), gfp); 187f87d0fbbSRusty Russell if (new) { 188f87d0fbbSRusty Russell memcpy(new, iov->iov, 189f87d0fbbSRusty Russell iov->max_num * sizeof(struct iovec)); 190f87d0fbbSRusty Russell flag = VRINGH_IOV_ALLOCATED; 191f87d0fbbSRusty Russell } 192f87d0fbbSRusty Russell } 193f87d0fbbSRusty Russell if (!new) 194f87d0fbbSRusty Russell return -ENOMEM; 195f87d0fbbSRusty Russell iov->iov = new; 196f87d0fbbSRusty Russell iov->max_num = (new_num | flag); 197f87d0fbbSRusty Russell return 0; 198f87d0fbbSRusty Russell } 199f87d0fbbSRusty Russell 200f87d0fbbSRusty Russell static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next, 201f87d0fbbSRusty Russell struct vring_desc **descs, int *desc_max) 202f87d0fbbSRusty Russell { 203f87d0fbbSRusty Russell u16 i = *up_next; 204f87d0fbbSRusty Russell 205f87d0fbbSRusty Russell *up_next = -1; 206f87d0fbbSRusty Russell *descs = vrh->vring.desc; 207f87d0fbbSRusty Russell *desc_max = vrh->vring.num; 208f87d0fbbSRusty Russell return i; 209f87d0fbbSRusty Russell } 210f87d0fbbSRusty Russell 211f87d0fbbSRusty Russell static int slow_copy(struct vringh *vrh, void *dst, const void *src, 212f87d0fbbSRusty Russell bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len, 213f87d0fbbSRusty Russell struct vringh_range *range, 214f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 215f87d0fbbSRusty Russell u64, 216f87d0fbbSRusty Russell struct vringh_range *)), 217f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 218f87d0fbbSRusty Russell u64 addr, 219f87d0fbbSRusty Russell struct vringh_range *r), 220f87d0fbbSRusty Russell struct vringh_range *range, 221f87d0fbbSRusty Russell int (*copy)(void *dst, const void *src, size_t len)) 222f87d0fbbSRusty Russell { 223f87d0fbbSRusty Russell size_t part, len = sizeof(struct vring_desc); 224f87d0fbbSRusty Russell 225f87d0fbbSRusty Russell do { 226f87d0fbbSRusty Russell u64 addr; 227f87d0fbbSRusty Russell int err; 228f87d0fbbSRusty Russell 229f87d0fbbSRusty Russell part = len; 230f87d0fbbSRusty Russell addr = (u64)(unsigned long)src - range->offset; 231f87d0fbbSRusty Russell 232f87d0fbbSRusty Russell if (!rcheck(vrh, addr, &part, range, getrange)) 233f87d0fbbSRusty Russell return -EINVAL; 234f87d0fbbSRusty Russell 235f87d0fbbSRusty Russell err = copy(dst, src, part); 236f87d0fbbSRusty Russell if (err) 237f87d0fbbSRusty Russell return err; 238f87d0fbbSRusty Russell 239f87d0fbbSRusty Russell dst += part; 240f87d0fbbSRusty Russell src += part; 241f87d0fbbSRusty Russell len -= part; 242f87d0fbbSRusty Russell } while (len); 243f87d0fbbSRusty Russell return 0; 244f87d0fbbSRusty Russell } 245f87d0fbbSRusty Russell 246f87d0fbbSRusty Russell static inline int 247f87d0fbbSRusty Russell __vringh_iov(struct vringh *vrh, u16 i, 248f87d0fbbSRusty Russell struct vringh_kiov *riov, 249f87d0fbbSRusty Russell struct vringh_kiov *wiov, 250f87d0fbbSRusty Russell bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len, 251f87d0fbbSRusty Russell struct vringh_range *range, 252f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, u64, 253f87d0fbbSRusty Russell struct vringh_range *)), 254f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, u64, struct vringh_range *), 255f87d0fbbSRusty Russell gfp_t gfp, 256f87d0fbbSRusty Russell int (*copy)(void *dst, const void *src, size_t len)) 257f87d0fbbSRusty Russell { 258f87d0fbbSRusty Russell int err, count = 0, up_next, desc_max; 259f87d0fbbSRusty Russell struct vring_desc desc, *descs; 260f87d0fbbSRusty Russell struct vringh_range range = { -1ULL, 0 }, slowrange; 261f87d0fbbSRusty Russell bool slow = false; 262f87d0fbbSRusty Russell 263f87d0fbbSRusty Russell /* We start traversing vring's descriptor table. */ 264f87d0fbbSRusty Russell descs = vrh->vring.desc; 265f87d0fbbSRusty Russell desc_max = vrh->vring.num; 266f87d0fbbSRusty Russell up_next = -1; 267f87d0fbbSRusty Russell 268f87d0fbbSRusty Russell if (riov) 269f87d0fbbSRusty Russell riov->i = riov->used = 0; 270f87d0fbbSRusty Russell else if (wiov) 271f87d0fbbSRusty Russell wiov->i = wiov->used = 0; 272f87d0fbbSRusty Russell else 273f87d0fbbSRusty Russell /* You must want something! */ 274f87d0fbbSRusty Russell BUG(); 275f87d0fbbSRusty Russell 276f87d0fbbSRusty Russell for (;;) { 277f87d0fbbSRusty Russell void *addr; 278f87d0fbbSRusty Russell struct vringh_kiov *iov; 279f87d0fbbSRusty Russell size_t len; 280f87d0fbbSRusty Russell 281f87d0fbbSRusty Russell if (unlikely(slow)) 282f87d0fbbSRusty Russell err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange, 283f87d0fbbSRusty Russell &slowrange, copy); 284f87d0fbbSRusty Russell else 285f87d0fbbSRusty Russell err = copy(&desc, &descs[i], sizeof(desc)); 286f87d0fbbSRusty Russell if (unlikely(err)) 287f87d0fbbSRusty Russell goto fail; 288f87d0fbbSRusty Russell 289f87d0fbbSRusty Russell if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) { 290f87d0fbbSRusty Russell /* Make sure it's OK, and get offset. */ 291f87d0fbbSRusty Russell len = desc.len; 292f87d0fbbSRusty Russell if (!rcheck(vrh, desc.addr, &len, &range, getrange)) { 293f87d0fbbSRusty Russell err = -EINVAL; 294f87d0fbbSRusty Russell goto fail; 295f87d0fbbSRusty Russell } 296f87d0fbbSRusty Russell 297f87d0fbbSRusty Russell if (unlikely(len != desc.len)) { 298f87d0fbbSRusty Russell slow = true; 299f87d0fbbSRusty Russell /* We need to save this range to use offset */ 300f87d0fbbSRusty Russell slowrange = range; 301f87d0fbbSRusty Russell } 302f87d0fbbSRusty Russell 303f87d0fbbSRusty Russell addr = (void *)(long)(desc.addr + range.offset); 304f87d0fbbSRusty Russell err = move_to_indirect(&up_next, &i, addr, &desc, 305f87d0fbbSRusty Russell &descs, &desc_max); 306f87d0fbbSRusty Russell if (err) 307f87d0fbbSRusty Russell goto fail; 308f87d0fbbSRusty Russell continue; 309f87d0fbbSRusty Russell } 310f87d0fbbSRusty Russell 311f87d0fbbSRusty Russell if (count++ == vrh->vring.num) { 312f87d0fbbSRusty Russell vringh_bad("Descriptor loop in %p", descs); 313f87d0fbbSRusty Russell err = -ELOOP; 314f87d0fbbSRusty Russell goto fail; 315f87d0fbbSRusty Russell } 316f87d0fbbSRusty Russell 317f87d0fbbSRusty Russell if (desc.flags & VRING_DESC_F_WRITE) 318f87d0fbbSRusty Russell iov = wiov; 319f87d0fbbSRusty Russell else { 320f87d0fbbSRusty Russell iov = riov; 321f87d0fbbSRusty Russell if (unlikely(wiov && wiov->i)) { 322f87d0fbbSRusty Russell vringh_bad("Readable desc %p after writable", 323f87d0fbbSRusty Russell &descs[i]); 324f87d0fbbSRusty Russell err = -EINVAL; 325f87d0fbbSRusty Russell goto fail; 326f87d0fbbSRusty Russell } 327f87d0fbbSRusty Russell } 328f87d0fbbSRusty Russell 329f87d0fbbSRusty Russell if (!iov) { 330f87d0fbbSRusty Russell vringh_bad("Unexpected %s desc", 331f87d0fbbSRusty Russell !wiov ? "writable" : "readable"); 332f87d0fbbSRusty Russell err = -EPROTO; 333f87d0fbbSRusty Russell goto fail; 334f87d0fbbSRusty Russell } 335f87d0fbbSRusty Russell 336f87d0fbbSRusty Russell again: 337f87d0fbbSRusty Russell /* Make sure it's OK, and get offset. */ 338f87d0fbbSRusty Russell len = desc.len; 339f87d0fbbSRusty Russell if (!rcheck(vrh, desc.addr, &len, &range, getrange)) { 340f87d0fbbSRusty Russell err = -EINVAL; 341f87d0fbbSRusty Russell goto fail; 342f87d0fbbSRusty Russell } 343f87d0fbbSRusty Russell addr = (void *)(unsigned long)(desc.addr + range.offset); 344f87d0fbbSRusty Russell 345f87d0fbbSRusty Russell if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) { 346f87d0fbbSRusty Russell err = resize_iovec(iov, gfp); 347f87d0fbbSRusty Russell if (err) 348f87d0fbbSRusty Russell goto fail; 349f87d0fbbSRusty Russell } 350f87d0fbbSRusty Russell 351f87d0fbbSRusty Russell iov->iov[iov->used].iov_base = addr; 352f87d0fbbSRusty Russell iov->iov[iov->used].iov_len = len; 353f87d0fbbSRusty Russell iov->used++; 354f87d0fbbSRusty Russell 355f87d0fbbSRusty Russell if (unlikely(len != desc.len)) { 356f87d0fbbSRusty Russell desc.len -= len; 357f87d0fbbSRusty Russell desc.addr += len; 358f87d0fbbSRusty Russell goto again; 359f87d0fbbSRusty Russell } 360f87d0fbbSRusty Russell 361f87d0fbbSRusty Russell if (desc.flags & VRING_DESC_F_NEXT) { 362f87d0fbbSRusty Russell i = desc.next; 363f87d0fbbSRusty Russell } else { 364f87d0fbbSRusty Russell /* Just in case we need to finish traversing above. */ 365f87d0fbbSRusty Russell if (unlikely(up_next > 0)) { 366f87d0fbbSRusty Russell i = return_from_indirect(vrh, &up_next, 367f87d0fbbSRusty Russell &descs, &desc_max); 368f87d0fbbSRusty Russell slow = false; 369f87d0fbbSRusty Russell } else 370f87d0fbbSRusty Russell break; 371f87d0fbbSRusty Russell } 372f87d0fbbSRusty Russell 373f87d0fbbSRusty Russell if (i >= desc_max) { 374f87d0fbbSRusty Russell vringh_bad("Chained index %u > %u", i, desc_max); 375f87d0fbbSRusty Russell err = -EINVAL; 376f87d0fbbSRusty Russell goto fail; 377f87d0fbbSRusty Russell } 378f87d0fbbSRusty Russell } 379f87d0fbbSRusty Russell 380f87d0fbbSRusty Russell return 0; 381f87d0fbbSRusty Russell 382f87d0fbbSRusty Russell fail: 383f87d0fbbSRusty Russell return err; 384f87d0fbbSRusty Russell } 385f87d0fbbSRusty Russell 386f87d0fbbSRusty Russell static inline int __vringh_complete(struct vringh *vrh, 387f87d0fbbSRusty Russell const struct vring_used_elem *used, 388f87d0fbbSRusty Russell unsigned int num_used, 389f87d0fbbSRusty Russell int (*putu16)(u16 *p, u16 val), 390f87d0fbbSRusty Russell int (*putused)(struct vring_used_elem *dst, 391f87d0fbbSRusty Russell const struct vring_used_elem 392f87d0fbbSRusty Russell *src, unsigned num)) 393f87d0fbbSRusty Russell { 394f87d0fbbSRusty Russell struct vring_used *used_ring; 395f87d0fbbSRusty Russell int err; 396f87d0fbbSRusty Russell u16 used_idx, off; 397f87d0fbbSRusty Russell 398f87d0fbbSRusty Russell used_ring = vrh->vring.used; 399f87d0fbbSRusty Russell used_idx = vrh->last_used_idx + vrh->completed; 400f87d0fbbSRusty Russell 401f87d0fbbSRusty Russell off = used_idx % vrh->vring.num; 402f87d0fbbSRusty Russell 403f87d0fbbSRusty Russell /* Compiler knows num_used == 1 sometimes, hence extra check */ 404f87d0fbbSRusty Russell if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) { 405f87d0fbbSRusty Russell u16 part = vrh->vring.num - off; 406f87d0fbbSRusty Russell err = putused(&used_ring->ring[off], used, part); 407f87d0fbbSRusty Russell if (!err) 408f87d0fbbSRusty Russell err = putused(&used_ring->ring[0], used + part, 409f87d0fbbSRusty Russell num_used - part); 410f87d0fbbSRusty Russell } else 411f87d0fbbSRusty Russell err = putused(&used_ring->ring[off], used, num_used); 412f87d0fbbSRusty Russell 413f87d0fbbSRusty Russell if (err) { 414f87d0fbbSRusty Russell vringh_bad("Failed to write %u used entries %u at %p", 415f87d0fbbSRusty Russell num_used, off, &used_ring->ring[off]); 416f87d0fbbSRusty Russell return err; 417f87d0fbbSRusty Russell } 418f87d0fbbSRusty Russell 419f87d0fbbSRusty Russell /* Make sure buffer is written before we update index. */ 420f87d0fbbSRusty Russell virtio_wmb(vrh->weak_barriers); 421f87d0fbbSRusty Russell 422f87d0fbbSRusty Russell err = putu16(&vrh->vring.used->idx, used_idx + num_used); 423f87d0fbbSRusty Russell if (err) { 424f87d0fbbSRusty Russell vringh_bad("Failed to update used index at %p", 425f87d0fbbSRusty Russell &vrh->vring.used->idx); 426f87d0fbbSRusty Russell return err; 427f87d0fbbSRusty Russell } 428f87d0fbbSRusty Russell 429f87d0fbbSRusty Russell vrh->completed += num_used; 430f87d0fbbSRusty Russell return 0; 431f87d0fbbSRusty Russell } 432f87d0fbbSRusty Russell 433f87d0fbbSRusty Russell 434f87d0fbbSRusty Russell static inline int __vringh_need_notify(struct vringh *vrh, 435f87d0fbbSRusty Russell int (*getu16)(u16 *val, const u16 *p)) 436f87d0fbbSRusty Russell { 437f87d0fbbSRusty Russell bool notify; 438f87d0fbbSRusty Russell u16 used_event; 439f87d0fbbSRusty Russell int err; 440f87d0fbbSRusty Russell 441f87d0fbbSRusty Russell /* Flush out used index update. This is paired with the 442f87d0fbbSRusty Russell * barrier that the Guest executes when enabling 443f87d0fbbSRusty Russell * interrupts. */ 444f87d0fbbSRusty Russell virtio_mb(vrh->weak_barriers); 445f87d0fbbSRusty Russell 446f87d0fbbSRusty Russell /* Old-style, without event indices. */ 447f87d0fbbSRusty Russell if (!vrh->event_indices) { 448f87d0fbbSRusty Russell u16 flags; 449f87d0fbbSRusty Russell err = getu16(&flags, &vrh->vring.avail->flags); 450f87d0fbbSRusty Russell if (err) { 451f87d0fbbSRusty Russell vringh_bad("Failed to get flags at %p", 452f87d0fbbSRusty Russell &vrh->vring.avail->flags); 453f87d0fbbSRusty Russell return err; 454f87d0fbbSRusty Russell } 455f87d0fbbSRusty Russell return (!(flags & VRING_AVAIL_F_NO_INTERRUPT)); 456f87d0fbbSRusty Russell } 457f87d0fbbSRusty Russell 458f87d0fbbSRusty Russell /* Modern: we know when other side wants to know. */ 459f87d0fbbSRusty Russell err = getu16(&used_event, &vring_used_event(&vrh->vring)); 460f87d0fbbSRusty Russell if (err) { 461f87d0fbbSRusty Russell vringh_bad("Failed to get used event idx at %p", 462f87d0fbbSRusty Russell &vring_used_event(&vrh->vring)); 463f87d0fbbSRusty Russell return err; 464f87d0fbbSRusty Russell } 465f87d0fbbSRusty Russell 466f87d0fbbSRusty Russell /* Just in case we added so many that we wrap. */ 467f87d0fbbSRusty Russell if (unlikely(vrh->completed > 0xffff)) 468f87d0fbbSRusty Russell notify = true; 469f87d0fbbSRusty Russell else 470f87d0fbbSRusty Russell notify = vring_need_event(used_event, 471f87d0fbbSRusty Russell vrh->last_used_idx + vrh->completed, 472f87d0fbbSRusty Russell vrh->last_used_idx); 473f87d0fbbSRusty Russell 474f87d0fbbSRusty Russell vrh->last_used_idx += vrh->completed; 475f87d0fbbSRusty Russell vrh->completed = 0; 476f87d0fbbSRusty Russell return notify; 477f87d0fbbSRusty Russell } 478f87d0fbbSRusty Russell 479f87d0fbbSRusty Russell static inline bool __vringh_notify_enable(struct vringh *vrh, 480f87d0fbbSRusty Russell int (*getu16)(u16 *val, const u16 *p), 481f87d0fbbSRusty Russell int (*putu16)(u16 *p, u16 val)) 482f87d0fbbSRusty Russell { 483f87d0fbbSRusty Russell u16 avail; 484f87d0fbbSRusty Russell 485f87d0fbbSRusty Russell if (!vrh->event_indices) { 486f87d0fbbSRusty Russell /* Old-school; update flags. */ 487f87d0fbbSRusty Russell if (putu16(&vrh->vring.used->flags, 0) != 0) { 488f87d0fbbSRusty Russell vringh_bad("Clearing used flags %p", 489f87d0fbbSRusty Russell &vrh->vring.used->flags); 490f87d0fbbSRusty Russell return true; 491f87d0fbbSRusty Russell } 492f87d0fbbSRusty Russell } else { 493f87d0fbbSRusty Russell if (putu16(&vring_avail_event(&vrh->vring), 494f87d0fbbSRusty Russell vrh->last_avail_idx) != 0) { 495f87d0fbbSRusty Russell vringh_bad("Updating avail event index %p", 496f87d0fbbSRusty Russell &vring_avail_event(&vrh->vring)); 497f87d0fbbSRusty Russell return true; 498f87d0fbbSRusty Russell } 499f87d0fbbSRusty Russell } 500f87d0fbbSRusty Russell 501f87d0fbbSRusty Russell /* They could have slipped one in as we were doing that: make 502f87d0fbbSRusty Russell * sure it's written, then check again. */ 503f87d0fbbSRusty Russell virtio_mb(vrh->weak_barriers); 504f87d0fbbSRusty Russell 505f87d0fbbSRusty Russell if (getu16(&avail, &vrh->vring.avail->idx) != 0) { 506f87d0fbbSRusty Russell vringh_bad("Failed to check avail idx at %p", 507f87d0fbbSRusty Russell &vrh->vring.avail->idx); 508f87d0fbbSRusty Russell return true; 509f87d0fbbSRusty Russell } 510f87d0fbbSRusty Russell 511f87d0fbbSRusty Russell /* This is unlikely, so we just leave notifications enabled 512f87d0fbbSRusty Russell * (if we're using event_indices, we'll only get one 513f87d0fbbSRusty Russell * notification anyway). */ 514f87d0fbbSRusty Russell return avail == vrh->last_avail_idx; 515f87d0fbbSRusty Russell } 516f87d0fbbSRusty Russell 517f87d0fbbSRusty Russell static inline void __vringh_notify_disable(struct vringh *vrh, 518f87d0fbbSRusty Russell int (*putu16)(u16 *p, u16 val)) 519f87d0fbbSRusty Russell { 520f87d0fbbSRusty Russell if (!vrh->event_indices) { 521f87d0fbbSRusty Russell /* Old-school; update flags. */ 522f87d0fbbSRusty Russell if (putu16(&vrh->vring.used->flags, VRING_USED_F_NO_NOTIFY)) { 523f87d0fbbSRusty Russell vringh_bad("Setting used flags %p", 524f87d0fbbSRusty Russell &vrh->vring.used->flags); 525f87d0fbbSRusty Russell } 526f87d0fbbSRusty Russell } 527f87d0fbbSRusty Russell } 528f87d0fbbSRusty Russell 529f87d0fbbSRusty Russell /* Userspace access helpers: in this case, addresses are really userspace. */ 530f87d0fbbSRusty Russell static inline int getu16_user(u16 *val, const u16 *p) 531f87d0fbbSRusty Russell { 532f87d0fbbSRusty Russell return get_user(*val, (__force u16 __user *)p); 533f87d0fbbSRusty Russell } 534f87d0fbbSRusty Russell 535f87d0fbbSRusty Russell static inline int putu16_user(u16 *p, u16 val) 536f87d0fbbSRusty Russell { 537f87d0fbbSRusty Russell return put_user(val, (__force u16 __user *)p); 538f87d0fbbSRusty Russell } 539f87d0fbbSRusty Russell 540f87d0fbbSRusty Russell static inline int copydesc_user(void *dst, const void *src, size_t len) 541f87d0fbbSRusty Russell { 542f87d0fbbSRusty Russell return copy_from_user(dst, (__force void __user *)src, len) ? 543f87d0fbbSRusty Russell -EFAULT : 0; 544f87d0fbbSRusty Russell } 545f87d0fbbSRusty Russell 546f87d0fbbSRusty Russell static inline int putused_user(struct vring_used_elem *dst, 547f87d0fbbSRusty Russell const struct vring_used_elem *src, 548f87d0fbbSRusty Russell unsigned int num) 549f87d0fbbSRusty Russell { 550f87d0fbbSRusty Russell return copy_to_user((__force void __user *)dst, src, 551f87d0fbbSRusty Russell sizeof(*dst) * num) ? -EFAULT : 0; 552f87d0fbbSRusty Russell } 553f87d0fbbSRusty Russell 554f87d0fbbSRusty Russell static inline int xfer_from_user(void *src, void *dst, size_t len) 555f87d0fbbSRusty Russell { 556f87d0fbbSRusty Russell return copy_from_user(dst, (__force void __user *)src, len) ? 557f87d0fbbSRusty Russell -EFAULT : 0; 558f87d0fbbSRusty Russell } 559f87d0fbbSRusty Russell 560f87d0fbbSRusty Russell static inline int xfer_to_user(void *dst, void *src, size_t len) 561f87d0fbbSRusty Russell { 562f87d0fbbSRusty Russell return copy_to_user((__force void __user *)dst, src, len) ? 563f87d0fbbSRusty Russell -EFAULT : 0; 564f87d0fbbSRusty Russell } 565f87d0fbbSRusty Russell 566f87d0fbbSRusty Russell /** 567f87d0fbbSRusty Russell * vringh_init_user - initialize a vringh for a userspace vring. 568f87d0fbbSRusty Russell * @vrh: the vringh to initialize. 569f87d0fbbSRusty Russell * @features: the feature bits for this ring. 570f87d0fbbSRusty Russell * @num: the number of elements. 571f87d0fbbSRusty Russell * @weak_barriers: true if we only need memory barriers, not I/O. 572f87d0fbbSRusty Russell * @desc: the userpace descriptor pointer. 573f87d0fbbSRusty Russell * @avail: the userpace avail pointer. 574f87d0fbbSRusty Russell * @used: the userpace used pointer. 575f87d0fbbSRusty Russell * 576f87d0fbbSRusty Russell * Returns an error if num is invalid: you should check pointers 577f87d0fbbSRusty Russell * yourself! 578f87d0fbbSRusty Russell */ 579f87d0fbbSRusty Russell int vringh_init_user(struct vringh *vrh, u32 features, 580f87d0fbbSRusty Russell unsigned int num, bool weak_barriers, 581f87d0fbbSRusty Russell struct vring_desc __user *desc, 582f87d0fbbSRusty Russell struct vring_avail __user *avail, 583f87d0fbbSRusty Russell struct vring_used __user *used) 584f87d0fbbSRusty Russell { 585f87d0fbbSRusty Russell /* Sane power of 2 please! */ 586f87d0fbbSRusty Russell if (!num || num > 0xffff || (num & (num - 1))) { 587f87d0fbbSRusty Russell vringh_bad("Bad ring size %u", num); 588f87d0fbbSRusty Russell return -EINVAL; 589f87d0fbbSRusty Russell } 590f87d0fbbSRusty Russell 591f87d0fbbSRusty Russell vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX)); 592f87d0fbbSRusty Russell vrh->weak_barriers = weak_barriers; 593f87d0fbbSRusty Russell vrh->completed = 0; 594f87d0fbbSRusty Russell vrh->last_avail_idx = 0; 595f87d0fbbSRusty Russell vrh->last_used_idx = 0; 596f87d0fbbSRusty Russell vrh->vring.num = num; 597f87d0fbbSRusty Russell /* vring expects kernel addresses, but only used via accessors. */ 598f87d0fbbSRusty Russell vrh->vring.desc = (__force struct vring_desc *)desc; 599f87d0fbbSRusty Russell vrh->vring.avail = (__force struct vring_avail *)avail; 600f87d0fbbSRusty Russell vrh->vring.used = (__force struct vring_used *)used; 601f87d0fbbSRusty Russell return 0; 602f87d0fbbSRusty Russell } 603f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_init_user); 604f87d0fbbSRusty Russell 605f87d0fbbSRusty Russell /** 606f87d0fbbSRusty Russell * vringh_getdesc_user - get next available descriptor from userspace ring. 607f87d0fbbSRusty Russell * @vrh: the userspace vring. 608f87d0fbbSRusty Russell * @riov: where to put the readable descriptors (or NULL) 609f87d0fbbSRusty Russell * @wiov: where to put the writable descriptors (or NULL) 610f87d0fbbSRusty Russell * @getrange: function to call to check ranges. 611f87d0fbbSRusty Russell * @head: head index we received, for passing to vringh_complete_user(). 612f87d0fbbSRusty Russell * 613f87d0fbbSRusty Russell * Returns 0 if there was no descriptor, 1 if there was, or -errno. 614f87d0fbbSRusty Russell * 615f87d0fbbSRusty Russell * Note that on error return, you can tell the difference between an 616f87d0fbbSRusty Russell * invalid ring and a single invalid descriptor: in the former case, 617f87d0fbbSRusty Russell * *head will be vrh->vring.num. You may be able to ignore an invalid 618f87d0fbbSRusty Russell * descriptor, but there's not much you can do with an invalid ring. 619f87d0fbbSRusty Russell * 620f87d0fbbSRusty Russell * Note that you may need to clean up riov and wiov, even on error! 621f87d0fbbSRusty Russell */ 622f87d0fbbSRusty Russell int vringh_getdesc_user(struct vringh *vrh, 623f87d0fbbSRusty Russell struct vringh_iov *riov, 624f87d0fbbSRusty Russell struct vringh_iov *wiov, 625f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 626f87d0fbbSRusty Russell u64 addr, struct vringh_range *r), 627f87d0fbbSRusty Russell u16 *head) 628f87d0fbbSRusty Russell { 629f87d0fbbSRusty Russell int err; 630f87d0fbbSRusty Russell 631f87d0fbbSRusty Russell *head = vrh->vring.num; 632f87d0fbbSRusty Russell err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx); 633f87d0fbbSRusty Russell if (err < 0) 634f87d0fbbSRusty Russell return err; 635f87d0fbbSRusty Russell 636f87d0fbbSRusty Russell /* Empty... */ 637f87d0fbbSRusty Russell if (err == vrh->vring.num) 638f87d0fbbSRusty Russell return 0; 639f87d0fbbSRusty Russell 640f87d0fbbSRusty Russell /* We need the layouts to be the identical for this to work */ 641f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov)); 642f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) != 643f87d0fbbSRusty Russell offsetof(struct vringh_iov, iov)); 644f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, i) != 645f87d0fbbSRusty Russell offsetof(struct vringh_iov, i)); 646f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, used) != 647f87d0fbbSRusty Russell offsetof(struct vringh_iov, used)); 648f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) != 649f87d0fbbSRusty Russell offsetof(struct vringh_iov, max_num)); 650f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); 651f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct iovec, iov_base) != 652f87d0fbbSRusty Russell offsetof(struct kvec, iov_base)); 653f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct iovec, iov_len) != 654f87d0fbbSRusty Russell offsetof(struct kvec, iov_len)); 655f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base) 656f87d0fbbSRusty Russell != sizeof(((struct kvec *)NULL)->iov_base)); 657f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len) 658f87d0fbbSRusty Russell != sizeof(((struct kvec *)NULL)->iov_len)); 659f87d0fbbSRusty Russell 660f87d0fbbSRusty Russell *head = err; 661f87d0fbbSRusty Russell err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov, 662f87d0fbbSRusty Russell (struct vringh_kiov *)wiov, 663f87d0fbbSRusty Russell range_check, getrange, GFP_KERNEL, copydesc_user); 664f87d0fbbSRusty Russell if (err) 665f87d0fbbSRusty Russell return err; 666f87d0fbbSRusty Russell 667f87d0fbbSRusty Russell return 1; 668f87d0fbbSRusty Russell } 669f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_getdesc_user); 670f87d0fbbSRusty Russell 671f87d0fbbSRusty Russell /** 672f87d0fbbSRusty Russell * vringh_iov_pull_user - copy bytes from vring_iov. 673f87d0fbbSRusty Russell * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume) 674f87d0fbbSRusty Russell * @dst: the place to copy. 675f87d0fbbSRusty Russell * @len: the maximum length to copy. 676f87d0fbbSRusty Russell * 677f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 678f87d0fbbSRusty Russell */ 679f87d0fbbSRusty Russell ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len) 680f87d0fbbSRusty Russell { 681f87d0fbbSRusty Russell return vringh_iov_xfer((struct vringh_kiov *)riov, 682f87d0fbbSRusty Russell dst, len, xfer_from_user); 683f87d0fbbSRusty Russell } 684f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_pull_user); 685f87d0fbbSRusty Russell 686f87d0fbbSRusty Russell /** 687f87d0fbbSRusty Russell * vringh_iov_push_user - copy bytes into vring_iov. 688f87d0fbbSRusty Russell * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume) 689f87d0fbbSRusty Russell * @dst: the place to copy. 690f87d0fbbSRusty Russell * @len: the maximum length to copy. 691f87d0fbbSRusty Russell * 692f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 693f87d0fbbSRusty Russell */ 694f87d0fbbSRusty Russell ssize_t vringh_iov_push_user(struct vringh_iov *wiov, 695f87d0fbbSRusty Russell const void *src, size_t len) 696f87d0fbbSRusty Russell { 697f87d0fbbSRusty Russell return vringh_iov_xfer((struct vringh_kiov *)wiov, 698f87d0fbbSRusty Russell (void *)src, len, xfer_to_user); 699f87d0fbbSRusty Russell } 700f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_push_user); 701f87d0fbbSRusty Russell 702f87d0fbbSRusty Russell /** 703f87d0fbbSRusty Russell * vringh_abandon_user - we've decided not to handle the descriptor(s). 704f87d0fbbSRusty Russell * @vrh: the vring. 705f87d0fbbSRusty Russell * @num: the number of descriptors to put back (ie. num 706f87d0fbbSRusty Russell * vringh_get_user() to undo). 707f87d0fbbSRusty Russell * 708f87d0fbbSRusty Russell * The next vringh_get_user() will return the old descriptor(s) again. 709f87d0fbbSRusty Russell */ 710f87d0fbbSRusty Russell void vringh_abandon_user(struct vringh *vrh, unsigned int num) 711f87d0fbbSRusty Russell { 712f87d0fbbSRusty Russell /* We only update vring_avail_event(vr) when we want to be notified, 713f87d0fbbSRusty Russell * so we haven't changed that yet. */ 714f87d0fbbSRusty Russell vrh->last_avail_idx -= num; 715f87d0fbbSRusty Russell } 716f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_abandon_user); 717f87d0fbbSRusty Russell 718f87d0fbbSRusty Russell /** 719f87d0fbbSRusty Russell * vringh_complete_user - we've finished with descriptor, publish it. 720f87d0fbbSRusty Russell * @vrh: the vring. 721f87d0fbbSRusty Russell * @head: the head as filled in by vringh_getdesc_user. 722f87d0fbbSRusty Russell * @len: the length of data we have written. 723f87d0fbbSRusty Russell * 724f87d0fbbSRusty Russell * You should check vringh_need_notify_user() after one or more calls 725f87d0fbbSRusty Russell * to this function. 726f87d0fbbSRusty Russell */ 727f87d0fbbSRusty Russell int vringh_complete_user(struct vringh *vrh, u16 head, u32 len) 728f87d0fbbSRusty Russell { 729f87d0fbbSRusty Russell struct vring_used_elem used; 730f87d0fbbSRusty Russell 731f87d0fbbSRusty Russell used.id = head; 732f87d0fbbSRusty Russell used.len = len; 733f87d0fbbSRusty Russell return __vringh_complete(vrh, &used, 1, putu16_user, putused_user); 734f87d0fbbSRusty Russell } 735f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_user); 736f87d0fbbSRusty Russell 737f87d0fbbSRusty Russell /** 738f87d0fbbSRusty Russell * vringh_complete_multi_user - we've finished with many descriptors. 739f87d0fbbSRusty Russell * @vrh: the vring. 740f87d0fbbSRusty Russell * @used: the head, length pairs. 741f87d0fbbSRusty Russell * @num_used: the number of used elements. 742f87d0fbbSRusty Russell * 743f87d0fbbSRusty Russell * You should check vringh_need_notify_user() after one or more calls 744f87d0fbbSRusty Russell * to this function. 745f87d0fbbSRusty Russell */ 746f87d0fbbSRusty Russell int vringh_complete_multi_user(struct vringh *vrh, 747f87d0fbbSRusty Russell const struct vring_used_elem used[], 748f87d0fbbSRusty Russell unsigned num_used) 749f87d0fbbSRusty Russell { 750f87d0fbbSRusty Russell return __vringh_complete(vrh, used, num_used, 751f87d0fbbSRusty Russell putu16_user, putused_user); 752f87d0fbbSRusty Russell } 753f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_multi_user); 754f87d0fbbSRusty Russell 755f87d0fbbSRusty Russell /** 756f87d0fbbSRusty Russell * vringh_notify_enable_user - we want to know if something changes. 757f87d0fbbSRusty Russell * @vrh: the vring. 758f87d0fbbSRusty Russell * 759f87d0fbbSRusty Russell * This always enables notifications, but returns false if there are 760f87d0fbbSRusty Russell * now more buffers available in the vring. 761f87d0fbbSRusty Russell */ 762f87d0fbbSRusty Russell bool vringh_notify_enable_user(struct vringh *vrh) 763f87d0fbbSRusty Russell { 764f87d0fbbSRusty Russell return __vringh_notify_enable(vrh, getu16_user, putu16_user); 765f87d0fbbSRusty Russell } 766f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_enable_user); 767f87d0fbbSRusty Russell 768f87d0fbbSRusty Russell /** 769f87d0fbbSRusty Russell * vringh_notify_disable_user - don't tell us if something changes. 770f87d0fbbSRusty Russell * @vrh: the vring. 771f87d0fbbSRusty Russell * 772f87d0fbbSRusty Russell * This is our normal running state: we disable and then only enable when 773f87d0fbbSRusty Russell * we're going to sleep. 774f87d0fbbSRusty Russell */ 775f87d0fbbSRusty Russell void vringh_notify_disable_user(struct vringh *vrh) 776f87d0fbbSRusty Russell { 777f87d0fbbSRusty Russell __vringh_notify_disable(vrh, putu16_user); 778f87d0fbbSRusty Russell } 779f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_disable_user); 780f87d0fbbSRusty Russell 781f87d0fbbSRusty Russell /** 782f87d0fbbSRusty Russell * vringh_need_notify_user - must we tell the other side about used buffers? 783f87d0fbbSRusty Russell * @vrh: the vring we've called vringh_complete_user() on. 784f87d0fbbSRusty Russell * 785f87d0fbbSRusty Russell * Returns -errno or 0 if we don't need to tell the other side, 1 if we do. 786f87d0fbbSRusty Russell */ 787f87d0fbbSRusty Russell int vringh_need_notify_user(struct vringh *vrh) 788f87d0fbbSRusty Russell { 789f87d0fbbSRusty Russell return __vringh_need_notify(vrh, getu16_user); 790f87d0fbbSRusty Russell } 791f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_need_notify_user); 792f87d0fbbSRusty Russell 793f87d0fbbSRusty Russell /* Kernelspace access helpers. */ 794f87d0fbbSRusty Russell static inline int getu16_kern(u16 *val, const u16 *p) 795f87d0fbbSRusty Russell { 796f87d0fbbSRusty Russell *val = ACCESS_ONCE(*p); 797f87d0fbbSRusty Russell return 0; 798f87d0fbbSRusty Russell } 799f87d0fbbSRusty Russell 800f87d0fbbSRusty Russell static inline int putu16_kern(u16 *p, u16 val) 801f87d0fbbSRusty Russell { 802f87d0fbbSRusty Russell ACCESS_ONCE(*p) = val; 803f87d0fbbSRusty Russell return 0; 804f87d0fbbSRusty Russell } 805f87d0fbbSRusty Russell 806f87d0fbbSRusty Russell static inline int copydesc_kern(void *dst, const void *src, size_t len) 807f87d0fbbSRusty Russell { 808f87d0fbbSRusty Russell memcpy(dst, src, len); 809f87d0fbbSRusty Russell return 0; 810f87d0fbbSRusty Russell } 811f87d0fbbSRusty Russell 812f87d0fbbSRusty Russell static inline int putused_kern(struct vring_used_elem *dst, 813f87d0fbbSRusty Russell const struct vring_used_elem *src, 814f87d0fbbSRusty Russell unsigned int num) 815f87d0fbbSRusty Russell { 816f87d0fbbSRusty Russell memcpy(dst, src, num * sizeof(*dst)); 817f87d0fbbSRusty Russell return 0; 818f87d0fbbSRusty Russell } 819f87d0fbbSRusty Russell 820f87d0fbbSRusty Russell static inline int xfer_kern(void *src, void *dst, size_t len) 821f87d0fbbSRusty Russell { 822f87d0fbbSRusty Russell memcpy(dst, src, len); 823f87d0fbbSRusty Russell return 0; 824f87d0fbbSRusty Russell } 825f87d0fbbSRusty Russell 826f87d0fbbSRusty Russell /** 827f87d0fbbSRusty Russell * vringh_init_kern - initialize a vringh for a kernelspace vring. 828f87d0fbbSRusty Russell * @vrh: the vringh to initialize. 829f87d0fbbSRusty Russell * @features: the feature bits for this ring. 830f87d0fbbSRusty Russell * @num: the number of elements. 831f87d0fbbSRusty Russell * @weak_barriers: true if we only need memory barriers, not I/O. 832f87d0fbbSRusty Russell * @desc: the userpace descriptor pointer. 833f87d0fbbSRusty Russell * @avail: the userpace avail pointer. 834f87d0fbbSRusty Russell * @used: the userpace used pointer. 835f87d0fbbSRusty Russell * 836f87d0fbbSRusty Russell * Returns an error if num is invalid. 837f87d0fbbSRusty Russell */ 838f87d0fbbSRusty Russell int vringh_init_kern(struct vringh *vrh, u32 features, 839f87d0fbbSRusty Russell unsigned int num, bool weak_barriers, 840f87d0fbbSRusty Russell struct vring_desc *desc, 841f87d0fbbSRusty Russell struct vring_avail *avail, 842f87d0fbbSRusty Russell struct vring_used *used) 843f87d0fbbSRusty Russell { 844f87d0fbbSRusty Russell /* Sane power of 2 please! */ 845f87d0fbbSRusty Russell if (!num || num > 0xffff || (num & (num - 1))) { 846f87d0fbbSRusty Russell vringh_bad("Bad ring size %u", num); 847f87d0fbbSRusty Russell return -EINVAL; 848f87d0fbbSRusty Russell } 849f87d0fbbSRusty Russell 850f87d0fbbSRusty Russell vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX)); 851f87d0fbbSRusty Russell vrh->weak_barriers = weak_barriers; 852f87d0fbbSRusty Russell vrh->completed = 0; 853f87d0fbbSRusty Russell vrh->last_avail_idx = 0; 854f87d0fbbSRusty Russell vrh->last_used_idx = 0; 855f87d0fbbSRusty Russell vrh->vring.num = num; 856f87d0fbbSRusty Russell vrh->vring.desc = desc; 857f87d0fbbSRusty Russell vrh->vring.avail = avail; 858f87d0fbbSRusty Russell vrh->vring.used = used; 859f87d0fbbSRusty Russell return 0; 860f87d0fbbSRusty Russell } 861f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_init_kern); 862f87d0fbbSRusty Russell 863f87d0fbbSRusty Russell /** 864f87d0fbbSRusty Russell * vringh_getdesc_kern - get next available descriptor from kernelspace ring. 865f87d0fbbSRusty Russell * @vrh: the kernelspace vring. 866f87d0fbbSRusty Russell * @riov: where to put the readable descriptors (or NULL) 867f87d0fbbSRusty Russell * @wiov: where to put the writable descriptors (or NULL) 868f87d0fbbSRusty Russell * @head: head index we received, for passing to vringh_complete_kern(). 869f87d0fbbSRusty Russell * @gfp: flags for allocating larger riov/wiov. 870f87d0fbbSRusty Russell * 871f87d0fbbSRusty Russell * Returns 0 if there was no descriptor, 1 if there was, or -errno. 872f87d0fbbSRusty Russell * 873f87d0fbbSRusty Russell * Note that on error return, you can tell the difference between an 874f87d0fbbSRusty Russell * invalid ring and a single invalid descriptor: in the former case, 875f87d0fbbSRusty Russell * *head will be vrh->vring.num. You may be able to ignore an invalid 876f87d0fbbSRusty Russell * descriptor, but there's not much you can do with an invalid ring. 877f87d0fbbSRusty Russell * 878f87d0fbbSRusty Russell * Note that you may need to clean up riov and wiov, even on error! 879f87d0fbbSRusty Russell */ 880f87d0fbbSRusty Russell int vringh_getdesc_kern(struct vringh *vrh, 881f87d0fbbSRusty Russell struct vringh_kiov *riov, 882f87d0fbbSRusty Russell struct vringh_kiov *wiov, 883f87d0fbbSRusty Russell u16 *head, 884f87d0fbbSRusty Russell gfp_t gfp) 885f87d0fbbSRusty Russell { 886f87d0fbbSRusty Russell int err; 887f87d0fbbSRusty Russell 888f87d0fbbSRusty Russell err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx); 889f87d0fbbSRusty Russell if (err < 0) 890f87d0fbbSRusty Russell return err; 891f87d0fbbSRusty Russell 892f87d0fbbSRusty Russell /* Empty... */ 893f87d0fbbSRusty Russell if (err == vrh->vring.num) 894f87d0fbbSRusty Russell return 0; 895f87d0fbbSRusty Russell 896f87d0fbbSRusty Russell *head = err; 897f87d0fbbSRusty Russell err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL, 898f87d0fbbSRusty Russell gfp, copydesc_kern); 899f87d0fbbSRusty Russell if (err) 900f87d0fbbSRusty Russell return err; 901f87d0fbbSRusty Russell 902f87d0fbbSRusty Russell return 1; 903f87d0fbbSRusty Russell } 904f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_getdesc_kern); 905f87d0fbbSRusty Russell 906f87d0fbbSRusty Russell /** 907f87d0fbbSRusty Russell * vringh_iov_pull_kern - copy bytes from vring_iov. 908f87d0fbbSRusty Russell * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume) 909f87d0fbbSRusty Russell * @dst: the place to copy. 910f87d0fbbSRusty Russell * @len: the maximum length to copy. 911f87d0fbbSRusty Russell * 912f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 913f87d0fbbSRusty Russell */ 914f87d0fbbSRusty Russell ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len) 915f87d0fbbSRusty Russell { 916f87d0fbbSRusty Russell return vringh_iov_xfer(riov, dst, len, xfer_kern); 917f87d0fbbSRusty Russell } 918f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_pull_kern); 919f87d0fbbSRusty Russell 920f87d0fbbSRusty Russell /** 921f87d0fbbSRusty Russell * vringh_iov_push_kern - copy bytes into vring_iov. 922f87d0fbbSRusty Russell * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume) 923f87d0fbbSRusty Russell * @dst: the place to copy. 924f87d0fbbSRusty Russell * @len: the maximum length to copy. 925f87d0fbbSRusty Russell * 926f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 927f87d0fbbSRusty Russell */ 928f87d0fbbSRusty Russell ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov, 929f87d0fbbSRusty Russell const void *src, size_t len) 930f87d0fbbSRusty Russell { 931f87d0fbbSRusty Russell return vringh_iov_xfer(wiov, (void *)src, len, xfer_kern); 932f87d0fbbSRusty Russell } 933f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_push_kern); 934f87d0fbbSRusty Russell 935f87d0fbbSRusty Russell /** 936f87d0fbbSRusty Russell * vringh_abandon_kern - we've decided not to handle the descriptor(s). 937f87d0fbbSRusty Russell * @vrh: the vring. 938f87d0fbbSRusty Russell * @num: the number of descriptors to put back (ie. num 939f87d0fbbSRusty Russell * vringh_get_kern() to undo). 940f87d0fbbSRusty Russell * 941f87d0fbbSRusty Russell * The next vringh_get_kern() will return the old descriptor(s) again. 942f87d0fbbSRusty Russell */ 943f87d0fbbSRusty Russell void vringh_abandon_kern(struct vringh *vrh, unsigned int num) 944f87d0fbbSRusty Russell { 945f87d0fbbSRusty Russell /* We only update vring_avail_event(vr) when we want to be notified, 946f87d0fbbSRusty Russell * so we haven't changed that yet. */ 947f87d0fbbSRusty Russell vrh->last_avail_idx -= num; 948f87d0fbbSRusty Russell } 949f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_abandon_kern); 950f87d0fbbSRusty Russell 951f87d0fbbSRusty Russell /** 952f87d0fbbSRusty Russell * vringh_complete_kern - we've finished with descriptor, publish it. 953f87d0fbbSRusty Russell * @vrh: the vring. 954f87d0fbbSRusty Russell * @head: the head as filled in by vringh_getdesc_kern. 955f87d0fbbSRusty Russell * @len: the length of data we have written. 956f87d0fbbSRusty Russell * 957f87d0fbbSRusty Russell * You should check vringh_need_notify_kern() after one or more calls 958f87d0fbbSRusty Russell * to this function. 959f87d0fbbSRusty Russell */ 960f87d0fbbSRusty Russell int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len) 961f87d0fbbSRusty Russell { 962f87d0fbbSRusty Russell struct vring_used_elem used; 963f87d0fbbSRusty Russell 964f87d0fbbSRusty Russell used.id = head; 965f87d0fbbSRusty Russell used.len = len; 966f87d0fbbSRusty Russell 967f87d0fbbSRusty Russell return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern); 968f87d0fbbSRusty Russell } 969f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_kern); 970f87d0fbbSRusty Russell 971f87d0fbbSRusty Russell /** 972f87d0fbbSRusty Russell * vringh_notify_enable_kern - we want to know if something changes. 973f87d0fbbSRusty Russell * @vrh: the vring. 974f87d0fbbSRusty Russell * 975f87d0fbbSRusty Russell * This always enables notifications, but returns false if there are 976f87d0fbbSRusty Russell * now more buffers available in the vring. 977f87d0fbbSRusty Russell */ 978f87d0fbbSRusty Russell bool vringh_notify_enable_kern(struct vringh *vrh) 979f87d0fbbSRusty Russell { 980f87d0fbbSRusty Russell return __vringh_notify_enable(vrh, getu16_kern, putu16_kern); 981f87d0fbbSRusty Russell } 982f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_enable_kern); 983f87d0fbbSRusty Russell 984f87d0fbbSRusty Russell /** 985f87d0fbbSRusty Russell * vringh_notify_disable_kern - don't tell us if something changes. 986f87d0fbbSRusty Russell * @vrh: the vring. 987f87d0fbbSRusty Russell * 988f87d0fbbSRusty Russell * This is our normal running state: we disable and then only enable when 989f87d0fbbSRusty Russell * we're going to sleep. 990f87d0fbbSRusty Russell */ 991f87d0fbbSRusty Russell void vringh_notify_disable_kern(struct vringh *vrh) 992f87d0fbbSRusty Russell { 993f87d0fbbSRusty Russell __vringh_notify_disable(vrh, putu16_kern); 994f87d0fbbSRusty Russell } 995f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_disable_kern); 996f87d0fbbSRusty Russell 997f87d0fbbSRusty Russell /** 998f87d0fbbSRusty Russell * vringh_need_notify_kern - must we tell the other side about used buffers? 999f87d0fbbSRusty Russell * @vrh: the vring we've called vringh_complete_kern() on. 1000f87d0fbbSRusty Russell * 1001f87d0fbbSRusty Russell * Returns -errno or 0 if we don't need to tell the other side, 1 if we do. 1002f87d0fbbSRusty Russell */ 1003f87d0fbbSRusty Russell int vringh_need_notify_kern(struct vringh *vrh) 1004f87d0fbbSRusty Russell { 1005f87d0fbbSRusty Russell return __vringh_need_notify(vrh, getu16_kern); 1006f87d0fbbSRusty Russell } 1007f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_need_notify_kern); 1008