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 */ 6f558a845SDave Jones #include <linux/module.h> 7f87d0fbbSRusty Russell #include <linux/vringh.h> 8f87d0fbbSRusty Russell #include <linux/virtio_ring.h> 9f87d0fbbSRusty Russell #include <linux/kernel.h> 10f87d0fbbSRusty Russell #include <linux/ratelimit.h> 11f87d0fbbSRusty Russell #include <linux/uaccess.h> 12f87d0fbbSRusty Russell #include <linux/slab.h> 13f87d0fbbSRusty Russell #include <linux/export.h> 14f87d0fbbSRusty Russell 15f87d0fbbSRusty Russell static __printf(1,2) __cold void vringh_bad(const char *fmt, ...) 16f87d0fbbSRusty Russell { 17f87d0fbbSRusty Russell static DEFINE_RATELIMIT_STATE(vringh_rs, 18f87d0fbbSRusty Russell DEFAULT_RATELIMIT_INTERVAL, 19f87d0fbbSRusty Russell DEFAULT_RATELIMIT_BURST); 20f87d0fbbSRusty Russell if (__ratelimit(&vringh_rs)) { 21f87d0fbbSRusty Russell va_list ap; 22f87d0fbbSRusty Russell va_start(ap, fmt); 23f87d0fbbSRusty Russell printk(KERN_NOTICE "vringh:"); 24f87d0fbbSRusty Russell vprintk(fmt, ap); 25f87d0fbbSRusty Russell va_end(ap); 26f87d0fbbSRusty Russell } 27f87d0fbbSRusty Russell } 28f87d0fbbSRusty Russell 29f87d0fbbSRusty Russell /* Returns vring->num if empty, -ve on error. */ 30f87d0fbbSRusty Russell static inline int __vringh_get_head(const struct vringh *vrh, 31f87d0fbbSRusty Russell int (*getu16)(u16 *val, const u16 *p), 32f87d0fbbSRusty Russell u16 *last_avail_idx) 33f87d0fbbSRusty Russell { 34f87d0fbbSRusty Russell u16 avail_idx, i, head; 35f87d0fbbSRusty Russell int err; 36f87d0fbbSRusty Russell 37f87d0fbbSRusty Russell err = getu16(&avail_idx, &vrh->vring.avail->idx); 38f87d0fbbSRusty Russell if (err) { 39f87d0fbbSRusty Russell vringh_bad("Failed to access avail idx at %p", 40f87d0fbbSRusty Russell &vrh->vring.avail->idx); 41f87d0fbbSRusty Russell return err; 42f87d0fbbSRusty Russell } 43f87d0fbbSRusty Russell 44f87d0fbbSRusty Russell if (*last_avail_idx == avail_idx) 45f87d0fbbSRusty Russell return vrh->vring.num; 46f87d0fbbSRusty Russell 47f87d0fbbSRusty Russell /* Only get avail ring entries after they have been exposed by guest. */ 48f87d0fbbSRusty Russell virtio_rmb(vrh->weak_barriers); 49f87d0fbbSRusty Russell 50f87d0fbbSRusty Russell i = *last_avail_idx & (vrh->vring.num - 1); 51f87d0fbbSRusty Russell 52f87d0fbbSRusty Russell err = getu16(&head, &vrh->vring.avail->ring[i]); 53f87d0fbbSRusty Russell if (err) { 54f87d0fbbSRusty Russell vringh_bad("Failed to read head: idx %d address %p", 55f87d0fbbSRusty Russell *last_avail_idx, &vrh->vring.avail->ring[i]); 56f87d0fbbSRusty Russell return err; 57f87d0fbbSRusty Russell } 58f87d0fbbSRusty Russell 59f87d0fbbSRusty Russell if (head >= vrh->vring.num) { 60f87d0fbbSRusty Russell vringh_bad("Guest says index %u > %u is available", 61f87d0fbbSRusty Russell head, vrh->vring.num); 62f87d0fbbSRusty Russell return -EINVAL; 63f87d0fbbSRusty Russell } 64f87d0fbbSRusty Russell 65f87d0fbbSRusty Russell (*last_avail_idx)++; 66f87d0fbbSRusty Russell return head; 67f87d0fbbSRusty Russell } 68f87d0fbbSRusty Russell 69f87d0fbbSRusty Russell /* Copy some bytes to/from the iovec. Returns num copied. */ 70f87d0fbbSRusty Russell static inline ssize_t vringh_iov_xfer(struct vringh_kiov *iov, 71f87d0fbbSRusty Russell void *ptr, size_t len, 72f87d0fbbSRusty Russell int (*xfer)(void *addr, void *ptr, 73f87d0fbbSRusty Russell size_t len)) 74f87d0fbbSRusty Russell { 75f87d0fbbSRusty Russell int err, done = 0; 76f87d0fbbSRusty Russell 77f87d0fbbSRusty Russell while (len && iov->i < iov->used) { 78f87d0fbbSRusty Russell size_t partlen; 79f87d0fbbSRusty Russell 80f87d0fbbSRusty Russell partlen = min(iov->iov[iov->i].iov_len, len); 81f87d0fbbSRusty Russell err = xfer(iov->iov[iov->i].iov_base, ptr, partlen); 82f87d0fbbSRusty Russell if (err) 83f87d0fbbSRusty Russell return err; 84f87d0fbbSRusty Russell done += partlen; 85f87d0fbbSRusty Russell len -= partlen; 86f87d0fbbSRusty Russell ptr += partlen; 87f87d0fbbSRusty Russell iov->consumed += partlen; 88f87d0fbbSRusty Russell iov->iov[iov->i].iov_len -= partlen; 89f87d0fbbSRusty Russell iov->iov[iov->i].iov_base += partlen; 90f87d0fbbSRusty Russell 91f87d0fbbSRusty Russell if (!iov->iov[iov->i].iov_len) { 92f87d0fbbSRusty Russell /* Fix up old iov element then increment. */ 93f87d0fbbSRusty Russell iov->iov[iov->i].iov_len = iov->consumed; 94f87d0fbbSRusty Russell iov->iov[iov->i].iov_base -= iov->consumed; 95f87d0fbbSRusty Russell 96f87d0fbbSRusty Russell iov->consumed = 0; 97f87d0fbbSRusty Russell iov->i++; 98f87d0fbbSRusty Russell } 99f87d0fbbSRusty Russell } 100f87d0fbbSRusty Russell return done; 101f87d0fbbSRusty Russell } 102f87d0fbbSRusty Russell 103f87d0fbbSRusty Russell /* May reduce *len if range is shorter. */ 104f87d0fbbSRusty Russell static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len, 105f87d0fbbSRusty Russell struct vringh_range *range, 106f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, 107f87d0fbbSRusty Russell u64, struct vringh_range *)) 108f87d0fbbSRusty Russell { 109f87d0fbbSRusty Russell if (addr < range->start || addr > range->end_incl) { 110f87d0fbbSRusty Russell if (!getrange(vrh, addr, range)) 111f87d0fbbSRusty Russell return false; 112f87d0fbbSRusty Russell } 113f87d0fbbSRusty Russell BUG_ON(addr < range->start || addr > range->end_incl); 114f87d0fbbSRusty Russell 115f87d0fbbSRusty Russell /* To end of memory? */ 116f87d0fbbSRusty Russell if (unlikely(addr + *len == 0)) { 117f87d0fbbSRusty Russell if (range->end_incl == -1ULL) 118f87d0fbbSRusty Russell return true; 119f87d0fbbSRusty Russell goto truncate; 120f87d0fbbSRusty Russell } 121f87d0fbbSRusty Russell 122f87d0fbbSRusty Russell /* Otherwise, don't wrap. */ 123f87d0fbbSRusty Russell if (addr + *len < addr) { 124f87d0fbbSRusty Russell vringh_bad("Wrapping descriptor %zu@0x%llx", 125f87d0fbbSRusty Russell *len, (unsigned long long)addr); 126f87d0fbbSRusty Russell return false; 127f87d0fbbSRusty Russell } 128f87d0fbbSRusty Russell 129f87d0fbbSRusty Russell if (unlikely(addr + *len - 1 > range->end_incl)) 130f87d0fbbSRusty Russell goto truncate; 131f87d0fbbSRusty Russell return true; 132f87d0fbbSRusty Russell 133f87d0fbbSRusty Russell truncate: 134f87d0fbbSRusty Russell *len = range->end_incl + 1 - addr; 135f87d0fbbSRusty Russell return true; 136f87d0fbbSRusty Russell } 137f87d0fbbSRusty Russell 138f87d0fbbSRusty Russell static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len, 139f87d0fbbSRusty Russell struct vringh_range *range, 140f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, 141f87d0fbbSRusty Russell u64, struct vringh_range *)) 142f87d0fbbSRusty Russell { 143f87d0fbbSRusty Russell return true; 144f87d0fbbSRusty Russell } 145f87d0fbbSRusty Russell 146f87d0fbbSRusty Russell /* No reason for this code to be inline. */ 147f87d0fbbSRusty Russell static int move_to_indirect(int *up_next, u16 *i, void *addr, 148f87d0fbbSRusty Russell const struct vring_desc *desc, 149f87d0fbbSRusty Russell struct vring_desc **descs, int *desc_max) 150f87d0fbbSRusty Russell { 151f87d0fbbSRusty Russell /* Indirect tables can't have indirect. */ 152f87d0fbbSRusty Russell if (*up_next != -1) { 153f87d0fbbSRusty Russell vringh_bad("Multilevel indirect %u->%u", *up_next, *i); 154f87d0fbbSRusty Russell return -EINVAL; 155f87d0fbbSRusty Russell } 156f87d0fbbSRusty Russell 157f87d0fbbSRusty Russell if (unlikely(desc->len % sizeof(struct vring_desc))) { 158f87d0fbbSRusty Russell vringh_bad("Strange indirect len %u", desc->len); 159f87d0fbbSRusty Russell return -EINVAL; 160f87d0fbbSRusty Russell } 161f87d0fbbSRusty Russell 162f87d0fbbSRusty Russell /* We will check this when we follow it! */ 163f87d0fbbSRusty Russell if (desc->flags & VRING_DESC_F_NEXT) 164f87d0fbbSRusty Russell *up_next = desc->next; 165f87d0fbbSRusty Russell else 166f87d0fbbSRusty Russell *up_next = -2; 167f87d0fbbSRusty Russell *descs = addr; 168f87d0fbbSRusty Russell *desc_max = desc->len / sizeof(struct vring_desc); 169f87d0fbbSRusty Russell 170f87d0fbbSRusty Russell /* Now, start at the first indirect. */ 171f87d0fbbSRusty Russell *i = 0; 172f87d0fbbSRusty Russell return 0; 173f87d0fbbSRusty Russell } 174f87d0fbbSRusty Russell 175f87d0fbbSRusty Russell static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp) 176f87d0fbbSRusty Russell { 177f87d0fbbSRusty Russell struct kvec *new; 178f87d0fbbSRusty Russell unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2; 179f87d0fbbSRusty Russell 180f87d0fbbSRusty Russell if (new_num < 8) 181f87d0fbbSRusty Russell new_num = 8; 182f87d0fbbSRusty Russell 183f87d0fbbSRusty Russell flag = (iov->max_num & VRINGH_IOV_ALLOCATED); 184f87d0fbbSRusty Russell if (flag) 185f87d0fbbSRusty Russell new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp); 186f87d0fbbSRusty Russell else { 187f87d0fbbSRusty Russell new = kmalloc(new_num * sizeof(struct iovec), gfp); 188f87d0fbbSRusty Russell if (new) { 189f87d0fbbSRusty Russell memcpy(new, iov->iov, 190f87d0fbbSRusty Russell iov->max_num * sizeof(struct iovec)); 191f87d0fbbSRusty Russell flag = VRINGH_IOV_ALLOCATED; 192f87d0fbbSRusty Russell } 193f87d0fbbSRusty Russell } 194f87d0fbbSRusty Russell if (!new) 195f87d0fbbSRusty Russell return -ENOMEM; 196f87d0fbbSRusty Russell iov->iov = new; 197f87d0fbbSRusty Russell iov->max_num = (new_num | flag); 198f87d0fbbSRusty Russell return 0; 199f87d0fbbSRusty Russell } 200f87d0fbbSRusty Russell 201f87d0fbbSRusty Russell static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next, 202f87d0fbbSRusty Russell struct vring_desc **descs, int *desc_max) 203f87d0fbbSRusty Russell { 204f87d0fbbSRusty Russell u16 i = *up_next; 205f87d0fbbSRusty Russell 206f87d0fbbSRusty Russell *up_next = -1; 207f87d0fbbSRusty Russell *descs = vrh->vring.desc; 208f87d0fbbSRusty Russell *desc_max = vrh->vring.num; 209f87d0fbbSRusty Russell return i; 210f87d0fbbSRusty Russell } 211f87d0fbbSRusty Russell 212f87d0fbbSRusty Russell static int slow_copy(struct vringh *vrh, void *dst, const void *src, 213f87d0fbbSRusty Russell bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len, 214f87d0fbbSRusty Russell struct vringh_range *range, 215f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 216f87d0fbbSRusty Russell u64, 217f87d0fbbSRusty Russell struct vringh_range *)), 218f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 219f87d0fbbSRusty Russell u64 addr, 220f87d0fbbSRusty Russell struct vringh_range *r), 221f87d0fbbSRusty Russell struct vringh_range *range, 222f87d0fbbSRusty Russell int (*copy)(void *dst, const void *src, size_t len)) 223f87d0fbbSRusty Russell { 224f87d0fbbSRusty Russell size_t part, len = sizeof(struct vring_desc); 225f87d0fbbSRusty Russell 226f87d0fbbSRusty Russell do { 227f87d0fbbSRusty Russell u64 addr; 228f87d0fbbSRusty Russell int err; 229f87d0fbbSRusty Russell 230f87d0fbbSRusty Russell part = len; 231f87d0fbbSRusty Russell addr = (u64)(unsigned long)src - range->offset; 232f87d0fbbSRusty Russell 233f87d0fbbSRusty Russell if (!rcheck(vrh, addr, &part, range, getrange)) 234f87d0fbbSRusty Russell return -EINVAL; 235f87d0fbbSRusty Russell 236f87d0fbbSRusty Russell err = copy(dst, src, part); 237f87d0fbbSRusty Russell if (err) 238f87d0fbbSRusty Russell return err; 239f87d0fbbSRusty Russell 240f87d0fbbSRusty Russell dst += part; 241f87d0fbbSRusty Russell src += part; 242f87d0fbbSRusty Russell len -= part; 243f87d0fbbSRusty Russell } while (len); 244f87d0fbbSRusty Russell return 0; 245f87d0fbbSRusty Russell } 246f87d0fbbSRusty Russell 247f87d0fbbSRusty Russell static inline int 248f87d0fbbSRusty Russell __vringh_iov(struct vringh *vrh, u16 i, 249f87d0fbbSRusty Russell struct vringh_kiov *riov, 250f87d0fbbSRusty Russell struct vringh_kiov *wiov, 251f87d0fbbSRusty Russell bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len, 252f87d0fbbSRusty Russell struct vringh_range *range, 253f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, u64, 254f87d0fbbSRusty Russell struct vringh_range *)), 255f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, u64, struct vringh_range *), 256f87d0fbbSRusty Russell gfp_t gfp, 257f87d0fbbSRusty Russell int (*copy)(void *dst, const void *src, size_t len)) 258f87d0fbbSRusty Russell { 259f87d0fbbSRusty Russell int err, count = 0, up_next, desc_max; 260f87d0fbbSRusty Russell struct vring_desc desc, *descs; 261f87d0fbbSRusty Russell struct vringh_range range = { -1ULL, 0 }, slowrange; 262f87d0fbbSRusty Russell bool slow = false; 263f87d0fbbSRusty Russell 264f87d0fbbSRusty Russell /* We start traversing vring's descriptor table. */ 265f87d0fbbSRusty Russell descs = vrh->vring.desc; 266f87d0fbbSRusty Russell desc_max = vrh->vring.num; 267f87d0fbbSRusty Russell up_next = -1; 268f87d0fbbSRusty Russell 269f87d0fbbSRusty Russell if (riov) 270f87d0fbbSRusty Russell riov->i = riov->used = 0; 271f87d0fbbSRusty Russell else if (wiov) 272f87d0fbbSRusty Russell wiov->i = wiov->used = 0; 273f87d0fbbSRusty Russell else 274f87d0fbbSRusty Russell /* You must want something! */ 275f87d0fbbSRusty Russell BUG(); 276f87d0fbbSRusty Russell 277f87d0fbbSRusty Russell for (;;) { 278f87d0fbbSRusty Russell void *addr; 279f87d0fbbSRusty Russell struct vringh_kiov *iov; 280f87d0fbbSRusty Russell size_t len; 281f87d0fbbSRusty Russell 282f87d0fbbSRusty Russell if (unlikely(slow)) 283f87d0fbbSRusty Russell err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange, 284f87d0fbbSRusty Russell &slowrange, copy); 285f87d0fbbSRusty Russell else 286f87d0fbbSRusty Russell err = copy(&desc, &descs[i], sizeof(desc)); 287f87d0fbbSRusty Russell if (unlikely(err)) 288f87d0fbbSRusty Russell goto fail; 289f87d0fbbSRusty Russell 290f87d0fbbSRusty Russell if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) { 291f87d0fbbSRusty Russell /* Make sure it's OK, and get offset. */ 292f87d0fbbSRusty Russell len = desc.len; 293f87d0fbbSRusty Russell if (!rcheck(vrh, desc.addr, &len, &range, getrange)) { 294f87d0fbbSRusty Russell err = -EINVAL; 295f87d0fbbSRusty Russell goto fail; 296f87d0fbbSRusty Russell } 297f87d0fbbSRusty Russell 298f87d0fbbSRusty Russell if (unlikely(len != desc.len)) { 299f87d0fbbSRusty Russell slow = true; 300f87d0fbbSRusty Russell /* We need to save this range to use offset */ 301f87d0fbbSRusty Russell slowrange = range; 302f87d0fbbSRusty Russell } 303f87d0fbbSRusty Russell 304f87d0fbbSRusty Russell addr = (void *)(long)(desc.addr + range.offset); 305f87d0fbbSRusty Russell err = move_to_indirect(&up_next, &i, addr, &desc, 306f87d0fbbSRusty Russell &descs, &desc_max); 307f87d0fbbSRusty Russell if (err) 308f87d0fbbSRusty Russell goto fail; 309f87d0fbbSRusty Russell continue; 310f87d0fbbSRusty Russell } 311f87d0fbbSRusty Russell 312f87d0fbbSRusty Russell if (count++ == vrh->vring.num) { 313f87d0fbbSRusty Russell vringh_bad("Descriptor loop in %p", descs); 314f87d0fbbSRusty Russell err = -ELOOP; 315f87d0fbbSRusty Russell goto fail; 316f87d0fbbSRusty Russell } 317f87d0fbbSRusty Russell 318f87d0fbbSRusty Russell if (desc.flags & VRING_DESC_F_WRITE) 319f87d0fbbSRusty Russell iov = wiov; 320f87d0fbbSRusty Russell else { 321f87d0fbbSRusty Russell iov = riov; 322f87d0fbbSRusty Russell if (unlikely(wiov && wiov->i)) { 323f87d0fbbSRusty Russell vringh_bad("Readable desc %p after writable", 324f87d0fbbSRusty Russell &descs[i]); 325f87d0fbbSRusty Russell err = -EINVAL; 326f87d0fbbSRusty Russell goto fail; 327f87d0fbbSRusty Russell } 328f87d0fbbSRusty Russell } 329f87d0fbbSRusty Russell 330f87d0fbbSRusty Russell if (!iov) { 331f87d0fbbSRusty Russell vringh_bad("Unexpected %s desc", 332f87d0fbbSRusty Russell !wiov ? "writable" : "readable"); 333f87d0fbbSRusty Russell err = -EPROTO; 334f87d0fbbSRusty Russell goto fail; 335f87d0fbbSRusty Russell } 336f87d0fbbSRusty Russell 337f87d0fbbSRusty Russell again: 338f87d0fbbSRusty Russell /* Make sure it's OK, and get offset. */ 339f87d0fbbSRusty Russell len = desc.len; 340f87d0fbbSRusty Russell if (!rcheck(vrh, desc.addr, &len, &range, getrange)) { 341f87d0fbbSRusty Russell err = -EINVAL; 342f87d0fbbSRusty Russell goto fail; 343f87d0fbbSRusty Russell } 344f87d0fbbSRusty Russell addr = (void *)(unsigned long)(desc.addr + range.offset); 345f87d0fbbSRusty Russell 346f87d0fbbSRusty Russell if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) { 347f87d0fbbSRusty Russell err = resize_iovec(iov, gfp); 348f87d0fbbSRusty Russell if (err) 349f87d0fbbSRusty Russell goto fail; 350f87d0fbbSRusty Russell } 351f87d0fbbSRusty Russell 352f87d0fbbSRusty Russell iov->iov[iov->used].iov_base = addr; 353f87d0fbbSRusty Russell iov->iov[iov->used].iov_len = len; 354f87d0fbbSRusty Russell iov->used++; 355f87d0fbbSRusty Russell 356f87d0fbbSRusty Russell if (unlikely(len != desc.len)) { 357f87d0fbbSRusty Russell desc.len -= len; 358f87d0fbbSRusty Russell desc.addr += len; 359f87d0fbbSRusty Russell goto again; 360f87d0fbbSRusty Russell } 361f87d0fbbSRusty Russell 362f87d0fbbSRusty Russell if (desc.flags & VRING_DESC_F_NEXT) { 363f87d0fbbSRusty Russell i = desc.next; 364f87d0fbbSRusty Russell } else { 365f87d0fbbSRusty Russell /* Just in case we need to finish traversing above. */ 366f87d0fbbSRusty Russell if (unlikely(up_next > 0)) { 367f87d0fbbSRusty Russell i = return_from_indirect(vrh, &up_next, 368f87d0fbbSRusty Russell &descs, &desc_max); 369f87d0fbbSRusty Russell slow = false; 370f87d0fbbSRusty Russell } else 371f87d0fbbSRusty Russell break; 372f87d0fbbSRusty Russell } 373f87d0fbbSRusty Russell 374f87d0fbbSRusty Russell if (i >= desc_max) { 375f87d0fbbSRusty Russell vringh_bad("Chained index %u > %u", i, desc_max); 376f87d0fbbSRusty Russell err = -EINVAL; 377f87d0fbbSRusty Russell goto fail; 378f87d0fbbSRusty Russell } 379f87d0fbbSRusty Russell } 380f87d0fbbSRusty Russell 381f87d0fbbSRusty Russell return 0; 382f87d0fbbSRusty Russell 383f87d0fbbSRusty Russell fail: 384f87d0fbbSRusty Russell return err; 385f87d0fbbSRusty Russell } 386f87d0fbbSRusty Russell 387f87d0fbbSRusty Russell static inline int __vringh_complete(struct vringh *vrh, 388f87d0fbbSRusty Russell const struct vring_used_elem *used, 389f87d0fbbSRusty Russell unsigned int num_used, 390f87d0fbbSRusty Russell int (*putu16)(u16 *p, u16 val), 391f87d0fbbSRusty Russell int (*putused)(struct vring_used_elem *dst, 392f87d0fbbSRusty Russell const struct vring_used_elem 393f87d0fbbSRusty Russell *src, unsigned num)) 394f87d0fbbSRusty Russell { 395f87d0fbbSRusty Russell struct vring_used *used_ring; 396f87d0fbbSRusty Russell int err; 397f87d0fbbSRusty Russell u16 used_idx, off; 398f87d0fbbSRusty Russell 399f87d0fbbSRusty Russell used_ring = vrh->vring.used; 400f87d0fbbSRusty Russell used_idx = vrh->last_used_idx + vrh->completed; 401f87d0fbbSRusty Russell 402f87d0fbbSRusty Russell off = used_idx % vrh->vring.num; 403f87d0fbbSRusty Russell 404f87d0fbbSRusty Russell /* Compiler knows num_used == 1 sometimes, hence extra check */ 405f87d0fbbSRusty Russell if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) { 406f87d0fbbSRusty Russell u16 part = vrh->vring.num - off; 407f87d0fbbSRusty Russell err = putused(&used_ring->ring[off], used, part); 408f87d0fbbSRusty Russell if (!err) 409f87d0fbbSRusty Russell err = putused(&used_ring->ring[0], used + part, 410f87d0fbbSRusty Russell num_used - part); 411f87d0fbbSRusty Russell } else 412f87d0fbbSRusty Russell err = putused(&used_ring->ring[off], used, num_used); 413f87d0fbbSRusty Russell 414f87d0fbbSRusty Russell if (err) { 415f87d0fbbSRusty Russell vringh_bad("Failed to write %u used entries %u at %p", 416f87d0fbbSRusty Russell num_used, off, &used_ring->ring[off]); 417f87d0fbbSRusty Russell return err; 418f87d0fbbSRusty Russell } 419f87d0fbbSRusty Russell 420f87d0fbbSRusty Russell /* Make sure buffer is written before we update index. */ 421f87d0fbbSRusty Russell virtio_wmb(vrh->weak_barriers); 422f87d0fbbSRusty Russell 423f87d0fbbSRusty Russell err = putu16(&vrh->vring.used->idx, used_idx + num_used); 424f87d0fbbSRusty Russell if (err) { 425f87d0fbbSRusty Russell vringh_bad("Failed to update used index at %p", 426f87d0fbbSRusty Russell &vrh->vring.used->idx); 427f87d0fbbSRusty Russell return err; 428f87d0fbbSRusty Russell } 429f87d0fbbSRusty Russell 430f87d0fbbSRusty Russell vrh->completed += num_used; 431f87d0fbbSRusty Russell return 0; 432f87d0fbbSRusty Russell } 433f87d0fbbSRusty Russell 434f87d0fbbSRusty Russell 435f87d0fbbSRusty Russell static inline int __vringh_need_notify(struct vringh *vrh, 436f87d0fbbSRusty Russell int (*getu16)(u16 *val, const u16 *p)) 437f87d0fbbSRusty Russell { 438f87d0fbbSRusty Russell bool notify; 439f87d0fbbSRusty Russell u16 used_event; 440f87d0fbbSRusty Russell int err; 441f87d0fbbSRusty Russell 442f87d0fbbSRusty Russell /* Flush out used index update. This is paired with the 443f87d0fbbSRusty Russell * barrier that the Guest executes when enabling 444f87d0fbbSRusty Russell * interrupts. */ 445f87d0fbbSRusty Russell virtio_mb(vrh->weak_barriers); 446f87d0fbbSRusty Russell 447f87d0fbbSRusty Russell /* Old-style, without event indices. */ 448f87d0fbbSRusty Russell if (!vrh->event_indices) { 449f87d0fbbSRusty Russell u16 flags; 450f87d0fbbSRusty Russell err = getu16(&flags, &vrh->vring.avail->flags); 451f87d0fbbSRusty Russell if (err) { 452f87d0fbbSRusty Russell vringh_bad("Failed to get flags at %p", 453f87d0fbbSRusty Russell &vrh->vring.avail->flags); 454f87d0fbbSRusty Russell return err; 455f87d0fbbSRusty Russell } 456f87d0fbbSRusty Russell return (!(flags & VRING_AVAIL_F_NO_INTERRUPT)); 457f87d0fbbSRusty Russell } 458f87d0fbbSRusty Russell 459f87d0fbbSRusty Russell /* Modern: we know when other side wants to know. */ 460f87d0fbbSRusty Russell err = getu16(&used_event, &vring_used_event(&vrh->vring)); 461f87d0fbbSRusty Russell if (err) { 462f87d0fbbSRusty Russell vringh_bad("Failed to get used event idx at %p", 463f87d0fbbSRusty Russell &vring_used_event(&vrh->vring)); 464f87d0fbbSRusty Russell return err; 465f87d0fbbSRusty Russell } 466f87d0fbbSRusty Russell 467f87d0fbbSRusty Russell /* Just in case we added so many that we wrap. */ 468f87d0fbbSRusty Russell if (unlikely(vrh->completed > 0xffff)) 469f87d0fbbSRusty Russell notify = true; 470f87d0fbbSRusty Russell else 471f87d0fbbSRusty Russell notify = vring_need_event(used_event, 472f87d0fbbSRusty Russell vrh->last_used_idx + vrh->completed, 473f87d0fbbSRusty Russell vrh->last_used_idx); 474f87d0fbbSRusty Russell 475f87d0fbbSRusty Russell vrh->last_used_idx += vrh->completed; 476f87d0fbbSRusty Russell vrh->completed = 0; 477f87d0fbbSRusty Russell return notify; 478f87d0fbbSRusty Russell } 479f87d0fbbSRusty Russell 480f87d0fbbSRusty Russell static inline bool __vringh_notify_enable(struct vringh *vrh, 481f87d0fbbSRusty Russell int (*getu16)(u16 *val, const u16 *p), 482f87d0fbbSRusty Russell int (*putu16)(u16 *p, u16 val)) 483f87d0fbbSRusty Russell { 484f87d0fbbSRusty Russell u16 avail; 485f87d0fbbSRusty Russell 486f87d0fbbSRusty Russell if (!vrh->event_indices) { 487f87d0fbbSRusty Russell /* Old-school; update flags. */ 488f87d0fbbSRusty Russell if (putu16(&vrh->vring.used->flags, 0) != 0) { 489f87d0fbbSRusty Russell vringh_bad("Clearing used flags %p", 490f87d0fbbSRusty Russell &vrh->vring.used->flags); 491f87d0fbbSRusty Russell return true; 492f87d0fbbSRusty Russell } 493f87d0fbbSRusty Russell } else { 494f87d0fbbSRusty Russell if (putu16(&vring_avail_event(&vrh->vring), 495f87d0fbbSRusty Russell vrh->last_avail_idx) != 0) { 496f87d0fbbSRusty Russell vringh_bad("Updating avail event index %p", 497f87d0fbbSRusty Russell &vring_avail_event(&vrh->vring)); 498f87d0fbbSRusty Russell return true; 499f87d0fbbSRusty Russell } 500f87d0fbbSRusty Russell } 501f87d0fbbSRusty Russell 502f87d0fbbSRusty Russell /* They could have slipped one in as we were doing that: make 503f87d0fbbSRusty Russell * sure it's written, then check again. */ 504f87d0fbbSRusty Russell virtio_mb(vrh->weak_barriers); 505f87d0fbbSRusty Russell 506f87d0fbbSRusty Russell if (getu16(&avail, &vrh->vring.avail->idx) != 0) { 507f87d0fbbSRusty Russell vringh_bad("Failed to check avail idx at %p", 508f87d0fbbSRusty Russell &vrh->vring.avail->idx); 509f87d0fbbSRusty Russell return true; 510f87d0fbbSRusty Russell } 511f87d0fbbSRusty Russell 512f87d0fbbSRusty Russell /* This is unlikely, so we just leave notifications enabled 513f87d0fbbSRusty Russell * (if we're using event_indices, we'll only get one 514f87d0fbbSRusty Russell * notification anyway). */ 515f87d0fbbSRusty Russell return avail == vrh->last_avail_idx; 516f87d0fbbSRusty Russell } 517f87d0fbbSRusty Russell 518f87d0fbbSRusty Russell static inline void __vringh_notify_disable(struct vringh *vrh, 519f87d0fbbSRusty Russell int (*putu16)(u16 *p, u16 val)) 520f87d0fbbSRusty Russell { 521f87d0fbbSRusty Russell if (!vrh->event_indices) { 522f87d0fbbSRusty Russell /* Old-school; update flags. */ 523f87d0fbbSRusty Russell if (putu16(&vrh->vring.used->flags, VRING_USED_F_NO_NOTIFY)) { 524f87d0fbbSRusty Russell vringh_bad("Setting used flags %p", 525f87d0fbbSRusty Russell &vrh->vring.used->flags); 526f87d0fbbSRusty Russell } 527f87d0fbbSRusty Russell } 528f87d0fbbSRusty Russell } 529f87d0fbbSRusty Russell 530f87d0fbbSRusty Russell /* Userspace access helpers: in this case, addresses are really userspace. */ 531f87d0fbbSRusty Russell static inline int getu16_user(u16 *val, const u16 *p) 532f87d0fbbSRusty Russell { 533f87d0fbbSRusty Russell return get_user(*val, (__force u16 __user *)p); 534f87d0fbbSRusty Russell } 535f87d0fbbSRusty Russell 536f87d0fbbSRusty Russell static inline int putu16_user(u16 *p, u16 val) 537f87d0fbbSRusty Russell { 538f87d0fbbSRusty Russell return put_user(val, (__force u16 __user *)p); 539f87d0fbbSRusty Russell } 540f87d0fbbSRusty Russell 541f87d0fbbSRusty Russell static inline int copydesc_user(void *dst, const void *src, size_t len) 542f87d0fbbSRusty Russell { 543f87d0fbbSRusty Russell return copy_from_user(dst, (__force void __user *)src, len) ? 544f87d0fbbSRusty Russell -EFAULT : 0; 545f87d0fbbSRusty Russell } 546f87d0fbbSRusty Russell 547f87d0fbbSRusty Russell static inline int putused_user(struct vring_used_elem *dst, 548f87d0fbbSRusty Russell const struct vring_used_elem *src, 549f87d0fbbSRusty Russell unsigned int num) 550f87d0fbbSRusty Russell { 551f87d0fbbSRusty Russell return copy_to_user((__force void __user *)dst, src, 552f87d0fbbSRusty Russell sizeof(*dst) * num) ? -EFAULT : 0; 553f87d0fbbSRusty Russell } 554f87d0fbbSRusty Russell 555f87d0fbbSRusty Russell static inline int xfer_from_user(void *src, void *dst, size_t len) 556f87d0fbbSRusty Russell { 557f87d0fbbSRusty Russell return copy_from_user(dst, (__force void __user *)src, len) ? 558f87d0fbbSRusty Russell -EFAULT : 0; 559f87d0fbbSRusty Russell } 560f87d0fbbSRusty Russell 561f87d0fbbSRusty Russell static inline int xfer_to_user(void *dst, void *src, size_t len) 562f87d0fbbSRusty Russell { 563f87d0fbbSRusty Russell return copy_to_user((__force void __user *)dst, src, len) ? 564f87d0fbbSRusty Russell -EFAULT : 0; 565f87d0fbbSRusty Russell } 566f87d0fbbSRusty Russell 567f87d0fbbSRusty Russell /** 568f87d0fbbSRusty Russell * vringh_init_user - initialize a vringh for a userspace vring. 569f87d0fbbSRusty Russell * @vrh: the vringh to initialize. 570f87d0fbbSRusty Russell * @features: the feature bits for this ring. 571f87d0fbbSRusty Russell * @num: the number of elements. 572f87d0fbbSRusty Russell * @weak_barriers: true if we only need memory barriers, not I/O. 573f87d0fbbSRusty Russell * @desc: the userpace descriptor pointer. 574f87d0fbbSRusty Russell * @avail: the userpace avail pointer. 575f87d0fbbSRusty Russell * @used: the userpace used pointer. 576f87d0fbbSRusty Russell * 577f87d0fbbSRusty Russell * Returns an error if num is invalid: you should check pointers 578f87d0fbbSRusty Russell * yourself! 579f87d0fbbSRusty Russell */ 580f87d0fbbSRusty Russell int vringh_init_user(struct vringh *vrh, u32 features, 581f87d0fbbSRusty Russell unsigned int num, bool weak_barriers, 582f87d0fbbSRusty Russell struct vring_desc __user *desc, 583f87d0fbbSRusty Russell struct vring_avail __user *avail, 584f87d0fbbSRusty Russell struct vring_used __user *used) 585f87d0fbbSRusty Russell { 586f87d0fbbSRusty Russell /* Sane power of 2 please! */ 587f87d0fbbSRusty Russell if (!num || num > 0xffff || (num & (num - 1))) { 588f87d0fbbSRusty Russell vringh_bad("Bad ring size %u", num); 589f87d0fbbSRusty Russell return -EINVAL; 590f87d0fbbSRusty Russell } 591f87d0fbbSRusty Russell 592f87d0fbbSRusty Russell vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX)); 593f87d0fbbSRusty Russell vrh->weak_barriers = weak_barriers; 594f87d0fbbSRusty Russell vrh->completed = 0; 595f87d0fbbSRusty Russell vrh->last_avail_idx = 0; 596f87d0fbbSRusty Russell vrh->last_used_idx = 0; 597f87d0fbbSRusty Russell vrh->vring.num = num; 598f87d0fbbSRusty Russell /* vring expects kernel addresses, but only used via accessors. */ 599f87d0fbbSRusty Russell vrh->vring.desc = (__force struct vring_desc *)desc; 600f87d0fbbSRusty Russell vrh->vring.avail = (__force struct vring_avail *)avail; 601f87d0fbbSRusty Russell vrh->vring.used = (__force struct vring_used *)used; 602f87d0fbbSRusty Russell return 0; 603f87d0fbbSRusty Russell } 604f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_init_user); 605f87d0fbbSRusty Russell 606f87d0fbbSRusty Russell /** 607f87d0fbbSRusty Russell * vringh_getdesc_user - get next available descriptor from userspace ring. 608f87d0fbbSRusty Russell * @vrh: the userspace vring. 609f87d0fbbSRusty Russell * @riov: where to put the readable descriptors (or NULL) 610f87d0fbbSRusty Russell * @wiov: where to put the writable descriptors (or NULL) 611f87d0fbbSRusty Russell * @getrange: function to call to check ranges. 612f87d0fbbSRusty Russell * @head: head index we received, for passing to vringh_complete_user(). 613f87d0fbbSRusty Russell * 614f87d0fbbSRusty Russell * Returns 0 if there was no descriptor, 1 if there was, or -errno. 615f87d0fbbSRusty Russell * 616f87d0fbbSRusty Russell * Note that on error return, you can tell the difference between an 617f87d0fbbSRusty Russell * invalid ring and a single invalid descriptor: in the former case, 618f87d0fbbSRusty Russell * *head will be vrh->vring.num. You may be able to ignore an invalid 619f87d0fbbSRusty Russell * descriptor, but there's not much you can do with an invalid ring. 620f87d0fbbSRusty Russell * 621f87d0fbbSRusty Russell * Note that you may need to clean up riov and wiov, even on error! 622f87d0fbbSRusty Russell */ 623f87d0fbbSRusty Russell int vringh_getdesc_user(struct vringh *vrh, 624f87d0fbbSRusty Russell struct vringh_iov *riov, 625f87d0fbbSRusty Russell struct vringh_iov *wiov, 626f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 627f87d0fbbSRusty Russell u64 addr, struct vringh_range *r), 628f87d0fbbSRusty Russell u16 *head) 629f87d0fbbSRusty Russell { 630f87d0fbbSRusty Russell int err; 631f87d0fbbSRusty Russell 632f87d0fbbSRusty Russell *head = vrh->vring.num; 633f87d0fbbSRusty Russell err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx); 634f87d0fbbSRusty Russell if (err < 0) 635f87d0fbbSRusty Russell return err; 636f87d0fbbSRusty Russell 637f87d0fbbSRusty Russell /* Empty... */ 638f87d0fbbSRusty Russell if (err == vrh->vring.num) 639f87d0fbbSRusty Russell return 0; 640f87d0fbbSRusty Russell 641f87d0fbbSRusty Russell /* We need the layouts to be the identical for this to work */ 642f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov)); 643f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) != 644f87d0fbbSRusty Russell offsetof(struct vringh_iov, iov)); 645f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, i) != 646f87d0fbbSRusty Russell offsetof(struct vringh_iov, i)); 647f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, used) != 648f87d0fbbSRusty Russell offsetof(struct vringh_iov, used)); 649f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) != 650f87d0fbbSRusty Russell offsetof(struct vringh_iov, max_num)); 651f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); 652f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct iovec, iov_base) != 653f87d0fbbSRusty Russell offsetof(struct kvec, iov_base)); 654f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct iovec, iov_len) != 655f87d0fbbSRusty Russell offsetof(struct kvec, iov_len)); 656f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base) 657f87d0fbbSRusty Russell != sizeof(((struct kvec *)NULL)->iov_base)); 658f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len) 659f87d0fbbSRusty Russell != sizeof(((struct kvec *)NULL)->iov_len)); 660f87d0fbbSRusty Russell 661f87d0fbbSRusty Russell *head = err; 662f87d0fbbSRusty Russell err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov, 663f87d0fbbSRusty Russell (struct vringh_kiov *)wiov, 664f87d0fbbSRusty Russell range_check, getrange, GFP_KERNEL, copydesc_user); 665f87d0fbbSRusty Russell if (err) 666f87d0fbbSRusty Russell return err; 667f87d0fbbSRusty Russell 668f87d0fbbSRusty Russell return 1; 669f87d0fbbSRusty Russell } 670f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_getdesc_user); 671f87d0fbbSRusty Russell 672f87d0fbbSRusty Russell /** 673f87d0fbbSRusty Russell * vringh_iov_pull_user - copy bytes from vring_iov. 674f87d0fbbSRusty Russell * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume) 675f87d0fbbSRusty Russell * @dst: the place to copy. 676f87d0fbbSRusty Russell * @len: the maximum length to copy. 677f87d0fbbSRusty Russell * 678f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 679f87d0fbbSRusty Russell */ 680f87d0fbbSRusty Russell ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len) 681f87d0fbbSRusty Russell { 682f87d0fbbSRusty Russell return vringh_iov_xfer((struct vringh_kiov *)riov, 683f87d0fbbSRusty Russell dst, len, xfer_from_user); 684f87d0fbbSRusty Russell } 685f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_pull_user); 686f87d0fbbSRusty Russell 687f87d0fbbSRusty Russell /** 688f87d0fbbSRusty Russell * vringh_iov_push_user - copy bytes into vring_iov. 689f87d0fbbSRusty Russell * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume) 690f87d0fbbSRusty Russell * @dst: the place to copy. 691f87d0fbbSRusty Russell * @len: the maximum length to copy. 692f87d0fbbSRusty Russell * 693f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 694f87d0fbbSRusty Russell */ 695f87d0fbbSRusty Russell ssize_t vringh_iov_push_user(struct vringh_iov *wiov, 696f87d0fbbSRusty Russell const void *src, size_t len) 697f87d0fbbSRusty Russell { 698f87d0fbbSRusty Russell return vringh_iov_xfer((struct vringh_kiov *)wiov, 699f87d0fbbSRusty Russell (void *)src, len, xfer_to_user); 700f87d0fbbSRusty Russell } 701f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_push_user); 702f87d0fbbSRusty Russell 703f87d0fbbSRusty Russell /** 704f87d0fbbSRusty Russell * vringh_abandon_user - we've decided not to handle the descriptor(s). 705f87d0fbbSRusty Russell * @vrh: the vring. 706f87d0fbbSRusty Russell * @num: the number of descriptors to put back (ie. num 707f87d0fbbSRusty Russell * vringh_get_user() to undo). 708f87d0fbbSRusty Russell * 709f87d0fbbSRusty Russell * The next vringh_get_user() will return the old descriptor(s) again. 710f87d0fbbSRusty Russell */ 711f87d0fbbSRusty Russell void vringh_abandon_user(struct vringh *vrh, unsigned int num) 712f87d0fbbSRusty Russell { 713f87d0fbbSRusty Russell /* We only update vring_avail_event(vr) when we want to be notified, 714f87d0fbbSRusty Russell * so we haven't changed that yet. */ 715f87d0fbbSRusty Russell vrh->last_avail_idx -= num; 716f87d0fbbSRusty Russell } 717f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_abandon_user); 718f87d0fbbSRusty Russell 719f87d0fbbSRusty Russell /** 720f87d0fbbSRusty Russell * vringh_complete_user - we've finished with descriptor, publish it. 721f87d0fbbSRusty Russell * @vrh: the vring. 722f87d0fbbSRusty Russell * @head: the head as filled in by vringh_getdesc_user. 723f87d0fbbSRusty Russell * @len: the length of data we have written. 724f87d0fbbSRusty Russell * 725f87d0fbbSRusty Russell * You should check vringh_need_notify_user() after one or more calls 726f87d0fbbSRusty Russell * to this function. 727f87d0fbbSRusty Russell */ 728f87d0fbbSRusty Russell int vringh_complete_user(struct vringh *vrh, u16 head, u32 len) 729f87d0fbbSRusty Russell { 730f87d0fbbSRusty Russell struct vring_used_elem used; 731f87d0fbbSRusty Russell 732f87d0fbbSRusty Russell used.id = head; 733f87d0fbbSRusty Russell used.len = len; 734f87d0fbbSRusty Russell return __vringh_complete(vrh, &used, 1, putu16_user, putused_user); 735f87d0fbbSRusty Russell } 736f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_user); 737f87d0fbbSRusty Russell 738f87d0fbbSRusty Russell /** 739f87d0fbbSRusty Russell * vringh_complete_multi_user - we've finished with many descriptors. 740f87d0fbbSRusty Russell * @vrh: the vring. 741f87d0fbbSRusty Russell * @used: the head, length pairs. 742f87d0fbbSRusty Russell * @num_used: the number of used elements. 743f87d0fbbSRusty Russell * 744f87d0fbbSRusty Russell * You should check vringh_need_notify_user() after one or more calls 745f87d0fbbSRusty Russell * to this function. 746f87d0fbbSRusty Russell */ 747f87d0fbbSRusty Russell int vringh_complete_multi_user(struct vringh *vrh, 748f87d0fbbSRusty Russell const struct vring_used_elem used[], 749f87d0fbbSRusty Russell unsigned num_used) 750f87d0fbbSRusty Russell { 751f87d0fbbSRusty Russell return __vringh_complete(vrh, used, num_used, 752f87d0fbbSRusty Russell putu16_user, putused_user); 753f87d0fbbSRusty Russell } 754f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_multi_user); 755f87d0fbbSRusty Russell 756f87d0fbbSRusty Russell /** 757f87d0fbbSRusty Russell * vringh_notify_enable_user - we want to know if something changes. 758f87d0fbbSRusty Russell * @vrh: the vring. 759f87d0fbbSRusty Russell * 760f87d0fbbSRusty Russell * This always enables notifications, but returns false if there are 761f87d0fbbSRusty Russell * now more buffers available in the vring. 762f87d0fbbSRusty Russell */ 763f87d0fbbSRusty Russell bool vringh_notify_enable_user(struct vringh *vrh) 764f87d0fbbSRusty Russell { 765f87d0fbbSRusty Russell return __vringh_notify_enable(vrh, getu16_user, putu16_user); 766f87d0fbbSRusty Russell } 767f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_enable_user); 768f87d0fbbSRusty Russell 769f87d0fbbSRusty Russell /** 770f87d0fbbSRusty Russell * vringh_notify_disable_user - don't tell us if something changes. 771f87d0fbbSRusty Russell * @vrh: the vring. 772f87d0fbbSRusty Russell * 773f87d0fbbSRusty Russell * This is our normal running state: we disable and then only enable when 774f87d0fbbSRusty Russell * we're going to sleep. 775f87d0fbbSRusty Russell */ 776f87d0fbbSRusty Russell void vringh_notify_disable_user(struct vringh *vrh) 777f87d0fbbSRusty Russell { 778f87d0fbbSRusty Russell __vringh_notify_disable(vrh, putu16_user); 779f87d0fbbSRusty Russell } 780f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_disable_user); 781f87d0fbbSRusty Russell 782f87d0fbbSRusty Russell /** 783f87d0fbbSRusty Russell * vringh_need_notify_user - must we tell the other side about used buffers? 784f87d0fbbSRusty Russell * @vrh: the vring we've called vringh_complete_user() on. 785f87d0fbbSRusty Russell * 786f87d0fbbSRusty Russell * Returns -errno or 0 if we don't need to tell the other side, 1 if we do. 787f87d0fbbSRusty Russell */ 788f87d0fbbSRusty Russell int vringh_need_notify_user(struct vringh *vrh) 789f87d0fbbSRusty Russell { 790f87d0fbbSRusty Russell return __vringh_need_notify(vrh, getu16_user); 791f87d0fbbSRusty Russell } 792f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_need_notify_user); 793f87d0fbbSRusty Russell 794f87d0fbbSRusty Russell /* Kernelspace access helpers. */ 795f87d0fbbSRusty Russell static inline int getu16_kern(u16 *val, const u16 *p) 796f87d0fbbSRusty Russell { 797f87d0fbbSRusty Russell *val = ACCESS_ONCE(*p); 798f87d0fbbSRusty Russell return 0; 799f87d0fbbSRusty Russell } 800f87d0fbbSRusty Russell 801f87d0fbbSRusty Russell static inline int putu16_kern(u16 *p, u16 val) 802f87d0fbbSRusty Russell { 803f87d0fbbSRusty Russell ACCESS_ONCE(*p) = val; 804f87d0fbbSRusty Russell return 0; 805f87d0fbbSRusty Russell } 806f87d0fbbSRusty Russell 807f87d0fbbSRusty Russell static inline int copydesc_kern(void *dst, const void *src, size_t len) 808f87d0fbbSRusty Russell { 809f87d0fbbSRusty Russell memcpy(dst, src, len); 810f87d0fbbSRusty Russell return 0; 811f87d0fbbSRusty Russell } 812f87d0fbbSRusty Russell 813f87d0fbbSRusty Russell static inline int putused_kern(struct vring_used_elem *dst, 814f87d0fbbSRusty Russell const struct vring_used_elem *src, 815f87d0fbbSRusty Russell unsigned int num) 816f87d0fbbSRusty Russell { 817f87d0fbbSRusty Russell memcpy(dst, src, num * sizeof(*dst)); 818f87d0fbbSRusty Russell return 0; 819f87d0fbbSRusty Russell } 820f87d0fbbSRusty Russell 821f87d0fbbSRusty Russell static inline int xfer_kern(void *src, void *dst, size_t len) 822f87d0fbbSRusty Russell { 823f87d0fbbSRusty Russell memcpy(dst, src, len); 824f87d0fbbSRusty Russell return 0; 825f87d0fbbSRusty Russell } 826f87d0fbbSRusty Russell 827f87d0fbbSRusty Russell /** 828f87d0fbbSRusty Russell * vringh_init_kern - initialize a vringh for a kernelspace vring. 829f87d0fbbSRusty Russell * @vrh: the vringh to initialize. 830f87d0fbbSRusty Russell * @features: the feature bits for this ring. 831f87d0fbbSRusty Russell * @num: the number of elements. 832f87d0fbbSRusty Russell * @weak_barriers: true if we only need memory barriers, not I/O. 833f87d0fbbSRusty Russell * @desc: the userpace descriptor pointer. 834f87d0fbbSRusty Russell * @avail: the userpace avail pointer. 835f87d0fbbSRusty Russell * @used: the userpace used pointer. 836f87d0fbbSRusty Russell * 837f87d0fbbSRusty Russell * Returns an error if num is invalid. 838f87d0fbbSRusty Russell */ 839f87d0fbbSRusty Russell int vringh_init_kern(struct vringh *vrh, u32 features, 840f87d0fbbSRusty Russell unsigned int num, bool weak_barriers, 841f87d0fbbSRusty Russell struct vring_desc *desc, 842f87d0fbbSRusty Russell struct vring_avail *avail, 843f87d0fbbSRusty Russell struct vring_used *used) 844f87d0fbbSRusty Russell { 845f87d0fbbSRusty Russell /* Sane power of 2 please! */ 846f87d0fbbSRusty Russell if (!num || num > 0xffff || (num & (num - 1))) { 847f87d0fbbSRusty Russell vringh_bad("Bad ring size %u", num); 848f87d0fbbSRusty Russell return -EINVAL; 849f87d0fbbSRusty Russell } 850f87d0fbbSRusty Russell 851f87d0fbbSRusty Russell vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX)); 852f87d0fbbSRusty Russell vrh->weak_barriers = weak_barriers; 853f87d0fbbSRusty Russell vrh->completed = 0; 854f87d0fbbSRusty Russell vrh->last_avail_idx = 0; 855f87d0fbbSRusty Russell vrh->last_used_idx = 0; 856f87d0fbbSRusty Russell vrh->vring.num = num; 857f87d0fbbSRusty Russell vrh->vring.desc = desc; 858f87d0fbbSRusty Russell vrh->vring.avail = avail; 859f87d0fbbSRusty Russell vrh->vring.used = used; 860f87d0fbbSRusty Russell return 0; 861f87d0fbbSRusty Russell } 862f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_init_kern); 863f87d0fbbSRusty Russell 864f87d0fbbSRusty Russell /** 865f87d0fbbSRusty Russell * vringh_getdesc_kern - get next available descriptor from kernelspace ring. 866f87d0fbbSRusty Russell * @vrh: the kernelspace vring. 867f87d0fbbSRusty Russell * @riov: where to put the readable descriptors (or NULL) 868f87d0fbbSRusty Russell * @wiov: where to put the writable descriptors (or NULL) 869f87d0fbbSRusty Russell * @head: head index we received, for passing to vringh_complete_kern(). 870f87d0fbbSRusty Russell * @gfp: flags for allocating larger riov/wiov. 871f87d0fbbSRusty Russell * 872f87d0fbbSRusty Russell * Returns 0 if there was no descriptor, 1 if there was, or -errno. 873f87d0fbbSRusty Russell * 874f87d0fbbSRusty Russell * Note that on error return, you can tell the difference between an 875f87d0fbbSRusty Russell * invalid ring and a single invalid descriptor: in the former case, 876f87d0fbbSRusty Russell * *head will be vrh->vring.num. You may be able to ignore an invalid 877f87d0fbbSRusty Russell * descriptor, but there's not much you can do with an invalid ring. 878f87d0fbbSRusty Russell * 879f87d0fbbSRusty Russell * Note that you may need to clean up riov and wiov, even on error! 880f87d0fbbSRusty Russell */ 881f87d0fbbSRusty Russell int vringh_getdesc_kern(struct vringh *vrh, 882f87d0fbbSRusty Russell struct vringh_kiov *riov, 883f87d0fbbSRusty Russell struct vringh_kiov *wiov, 884f87d0fbbSRusty Russell u16 *head, 885f87d0fbbSRusty Russell gfp_t gfp) 886f87d0fbbSRusty Russell { 887f87d0fbbSRusty Russell int err; 888f87d0fbbSRusty Russell 889f87d0fbbSRusty Russell err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx); 890f87d0fbbSRusty Russell if (err < 0) 891f87d0fbbSRusty Russell return err; 892f87d0fbbSRusty Russell 893f87d0fbbSRusty Russell /* Empty... */ 894f87d0fbbSRusty Russell if (err == vrh->vring.num) 895f87d0fbbSRusty Russell return 0; 896f87d0fbbSRusty Russell 897f87d0fbbSRusty Russell *head = err; 898f87d0fbbSRusty Russell err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL, 899f87d0fbbSRusty Russell gfp, copydesc_kern); 900f87d0fbbSRusty Russell if (err) 901f87d0fbbSRusty Russell return err; 902f87d0fbbSRusty Russell 903f87d0fbbSRusty Russell return 1; 904f87d0fbbSRusty Russell } 905f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_getdesc_kern); 906f87d0fbbSRusty Russell 907f87d0fbbSRusty Russell /** 908f87d0fbbSRusty Russell * vringh_iov_pull_kern - copy bytes from vring_iov. 909f87d0fbbSRusty Russell * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume) 910f87d0fbbSRusty Russell * @dst: the place to copy. 911f87d0fbbSRusty Russell * @len: the maximum length to copy. 912f87d0fbbSRusty Russell * 913f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 914f87d0fbbSRusty Russell */ 915f87d0fbbSRusty Russell ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len) 916f87d0fbbSRusty Russell { 917f87d0fbbSRusty Russell return vringh_iov_xfer(riov, dst, len, xfer_kern); 918f87d0fbbSRusty Russell } 919f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_pull_kern); 920f87d0fbbSRusty Russell 921f87d0fbbSRusty Russell /** 922f87d0fbbSRusty Russell * vringh_iov_push_kern - copy bytes into vring_iov. 923f87d0fbbSRusty Russell * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume) 924f87d0fbbSRusty Russell * @dst: the place to copy. 925f87d0fbbSRusty Russell * @len: the maximum length to copy. 926f87d0fbbSRusty Russell * 927f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 928f87d0fbbSRusty Russell */ 929f87d0fbbSRusty Russell ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov, 930f87d0fbbSRusty Russell const void *src, size_t len) 931f87d0fbbSRusty Russell { 932f87d0fbbSRusty Russell return vringh_iov_xfer(wiov, (void *)src, len, xfer_kern); 933f87d0fbbSRusty Russell } 934f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_push_kern); 935f87d0fbbSRusty Russell 936f87d0fbbSRusty Russell /** 937f87d0fbbSRusty Russell * vringh_abandon_kern - we've decided not to handle the descriptor(s). 938f87d0fbbSRusty Russell * @vrh: the vring. 939f87d0fbbSRusty Russell * @num: the number of descriptors to put back (ie. num 940f87d0fbbSRusty Russell * vringh_get_kern() to undo). 941f87d0fbbSRusty Russell * 942f87d0fbbSRusty Russell * The next vringh_get_kern() will return the old descriptor(s) again. 943f87d0fbbSRusty Russell */ 944f87d0fbbSRusty Russell void vringh_abandon_kern(struct vringh *vrh, unsigned int num) 945f87d0fbbSRusty Russell { 946f87d0fbbSRusty Russell /* We only update vring_avail_event(vr) when we want to be notified, 947f87d0fbbSRusty Russell * so we haven't changed that yet. */ 948f87d0fbbSRusty Russell vrh->last_avail_idx -= num; 949f87d0fbbSRusty Russell } 950f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_abandon_kern); 951f87d0fbbSRusty Russell 952f87d0fbbSRusty Russell /** 953f87d0fbbSRusty Russell * vringh_complete_kern - we've finished with descriptor, publish it. 954f87d0fbbSRusty Russell * @vrh: the vring. 955f87d0fbbSRusty Russell * @head: the head as filled in by vringh_getdesc_kern. 956f87d0fbbSRusty Russell * @len: the length of data we have written. 957f87d0fbbSRusty Russell * 958f87d0fbbSRusty Russell * You should check vringh_need_notify_kern() after one or more calls 959f87d0fbbSRusty Russell * to this function. 960f87d0fbbSRusty Russell */ 961f87d0fbbSRusty Russell int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len) 962f87d0fbbSRusty Russell { 963f87d0fbbSRusty Russell struct vring_used_elem used; 964f87d0fbbSRusty Russell 965f87d0fbbSRusty Russell used.id = head; 966f87d0fbbSRusty Russell used.len = len; 967f87d0fbbSRusty Russell 968f87d0fbbSRusty Russell return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern); 969f87d0fbbSRusty Russell } 970f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_kern); 971f87d0fbbSRusty Russell 972f87d0fbbSRusty Russell /** 973f87d0fbbSRusty Russell * vringh_notify_enable_kern - we want to know if something changes. 974f87d0fbbSRusty Russell * @vrh: the vring. 975f87d0fbbSRusty Russell * 976f87d0fbbSRusty Russell * This always enables notifications, but returns false if there are 977f87d0fbbSRusty Russell * now more buffers available in the vring. 978f87d0fbbSRusty Russell */ 979f87d0fbbSRusty Russell bool vringh_notify_enable_kern(struct vringh *vrh) 980f87d0fbbSRusty Russell { 981f87d0fbbSRusty Russell return __vringh_notify_enable(vrh, getu16_kern, putu16_kern); 982f87d0fbbSRusty Russell } 983f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_enable_kern); 984f87d0fbbSRusty Russell 985f87d0fbbSRusty Russell /** 986f87d0fbbSRusty Russell * vringh_notify_disable_kern - don't tell us if something changes. 987f87d0fbbSRusty Russell * @vrh: the vring. 988f87d0fbbSRusty Russell * 989f87d0fbbSRusty Russell * This is our normal running state: we disable and then only enable when 990f87d0fbbSRusty Russell * we're going to sleep. 991f87d0fbbSRusty Russell */ 992f87d0fbbSRusty Russell void vringh_notify_disable_kern(struct vringh *vrh) 993f87d0fbbSRusty Russell { 994f87d0fbbSRusty Russell __vringh_notify_disable(vrh, putu16_kern); 995f87d0fbbSRusty Russell } 996f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_disable_kern); 997f87d0fbbSRusty Russell 998f87d0fbbSRusty Russell /** 999f87d0fbbSRusty Russell * vringh_need_notify_kern - must we tell the other side about used buffers? 1000f87d0fbbSRusty Russell * @vrh: the vring we've called vringh_complete_kern() on. 1001f87d0fbbSRusty Russell * 1002f87d0fbbSRusty Russell * Returns -errno or 0 if we don't need to tell the other side, 1 if we do. 1003f87d0fbbSRusty Russell */ 1004f87d0fbbSRusty Russell int vringh_need_notify_kern(struct vringh *vrh) 1005f87d0fbbSRusty Russell { 1006f87d0fbbSRusty Russell return __vringh_need_notify(vrh, getu16_kern); 1007f87d0fbbSRusty Russell } 1008f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_need_notify_kern); 1009f558a845SDave Jones 1010f558a845SDave Jones MODULE_LICENSE("GPL"); 1011