109c434b8SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 2f87d0fbbSRusty Russell /* 3f87d0fbbSRusty Russell * Helpers for the host side of a virtio ring. 4f87d0fbbSRusty Russell * 5f87d0fbbSRusty Russell * Since these may be in userspace, we use (inline) accessors. 6f87d0fbbSRusty Russell */ 79d1b972fSMark Rutland #include <linux/compiler.h> 8f558a845SDave Jones #include <linux/module.h> 9f87d0fbbSRusty Russell #include <linux/vringh.h> 10f87d0fbbSRusty Russell #include <linux/virtio_ring.h> 11f87d0fbbSRusty Russell #include <linux/kernel.h> 12f87d0fbbSRusty Russell #include <linux/ratelimit.h> 13f87d0fbbSRusty Russell #include <linux/uaccess.h> 14f87d0fbbSRusty Russell #include <linux/slab.h> 15f87d0fbbSRusty Russell #include <linux/export.h> 16b9f7ac8cSMichael S. Tsirkin #include <uapi/linux/virtio_config.h> 17f87d0fbbSRusty Russell 18f87d0fbbSRusty Russell static __printf(1,2) __cold void vringh_bad(const char *fmt, ...) 19f87d0fbbSRusty Russell { 20f87d0fbbSRusty Russell static DEFINE_RATELIMIT_STATE(vringh_rs, 21f87d0fbbSRusty Russell DEFAULT_RATELIMIT_INTERVAL, 22f87d0fbbSRusty Russell DEFAULT_RATELIMIT_BURST); 23f87d0fbbSRusty Russell if (__ratelimit(&vringh_rs)) { 24f87d0fbbSRusty Russell va_list ap; 25f87d0fbbSRusty Russell va_start(ap, fmt); 26f87d0fbbSRusty Russell printk(KERN_NOTICE "vringh:"); 27f87d0fbbSRusty Russell vprintk(fmt, ap); 28f87d0fbbSRusty Russell va_end(ap); 29f87d0fbbSRusty Russell } 30f87d0fbbSRusty Russell } 31f87d0fbbSRusty Russell 32f87d0fbbSRusty Russell /* Returns vring->num if empty, -ve on error. */ 33f87d0fbbSRusty Russell static inline int __vringh_get_head(const struct vringh *vrh, 34b9f7ac8cSMichael S. Tsirkin int (*getu16)(const struct vringh *vrh, 35b9f7ac8cSMichael S. Tsirkin u16 *val, const __virtio16 *p), 36f87d0fbbSRusty Russell u16 *last_avail_idx) 37f87d0fbbSRusty Russell { 38f87d0fbbSRusty Russell u16 avail_idx, i, head; 39f87d0fbbSRusty Russell int err; 40f87d0fbbSRusty Russell 41b9f7ac8cSMichael S. Tsirkin err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx); 42f87d0fbbSRusty Russell if (err) { 43f87d0fbbSRusty Russell vringh_bad("Failed to access avail idx at %p", 44f87d0fbbSRusty Russell &vrh->vring.avail->idx); 45f87d0fbbSRusty Russell return err; 46f87d0fbbSRusty Russell } 47f87d0fbbSRusty Russell 48f87d0fbbSRusty Russell if (*last_avail_idx == avail_idx) 49f87d0fbbSRusty Russell return vrh->vring.num; 50f87d0fbbSRusty Russell 51f87d0fbbSRusty Russell /* Only get avail ring entries after they have been exposed by guest. */ 52f87d0fbbSRusty Russell virtio_rmb(vrh->weak_barriers); 53f87d0fbbSRusty Russell 54f87d0fbbSRusty Russell i = *last_avail_idx & (vrh->vring.num - 1); 55f87d0fbbSRusty Russell 56b9f7ac8cSMichael S. Tsirkin err = getu16(vrh, &head, &vrh->vring.avail->ring[i]); 57f87d0fbbSRusty Russell if (err) { 58f87d0fbbSRusty Russell vringh_bad("Failed to read head: idx %d address %p", 59f87d0fbbSRusty Russell *last_avail_idx, &vrh->vring.avail->ring[i]); 60f87d0fbbSRusty Russell return err; 61f87d0fbbSRusty Russell } 62f87d0fbbSRusty Russell 63f87d0fbbSRusty Russell if (head >= vrh->vring.num) { 64f87d0fbbSRusty Russell vringh_bad("Guest says index %u > %u is available", 65f87d0fbbSRusty Russell head, vrh->vring.num); 66f87d0fbbSRusty Russell return -EINVAL; 67f87d0fbbSRusty Russell } 68f87d0fbbSRusty Russell 69f87d0fbbSRusty Russell (*last_avail_idx)++; 70f87d0fbbSRusty Russell return head; 71f87d0fbbSRusty Russell } 72f87d0fbbSRusty Russell 73f87d0fbbSRusty Russell /* Copy some bytes to/from the iovec. Returns num copied. */ 74f87d0fbbSRusty Russell static inline ssize_t vringh_iov_xfer(struct vringh_kiov *iov, 75f87d0fbbSRusty Russell void *ptr, size_t len, 76f87d0fbbSRusty Russell int (*xfer)(void *addr, void *ptr, 77f87d0fbbSRusty Russell size_t len)) 78f87d0fbbSRusty Russell { 79f87d0fbbSRusty Russell int err, done = 0; 80f87d0fbbSRusty Russell 81f87d0fbbSRusty Russell while (len && iov->i < iov->used) { 82f87d0fbbSRusty Russell size_t partlen; 83f87d0fbbSRusty Russell 84f87d0fbbSRusty Russell partlen = min(iov->iov[iov->i].iov_len, len); 85f87d0fbbSRusty Russell err = xfer(iov->iov[iov->i].iov_base, ptr, partlen); 86f87d0fbbSRusty Russell if (err) 87f87d0fbbSRusty Russell return err; 88f87d0fbbSRusty Russell done += partlen; 89f87d0fbbSRusty Russell len -= partlen; 90f87d0fbbSRusty Russell ptr += partlen; 91f87d0fbbSRusty Russell iov->consumed += partlen; 92f87d0fbbSRusty Russell iov->iov[iov->i].iov_len -= partlen; 93f87d0fbbSRusty Russell iov->iov[iov->i].iov_base += partlen; 94f87d0fbbSRusty Russell 95f87d0fbbSRusty Russell if (!iov->iov[iov->i].iov_len) { 96f87d0fbbSRusty Russell /* Fix up old iov element then increment. */ 97f87d0fbbSRusty Russell iov->iov[iov->i].iov_len = iov->consumed; 98f87d0fbbSRusty Russell iov->iov[iov->i].iov_base -= iov->consumed; 99f87d0fbbSRusty Russell 100f87d0fbbSRusty Russell iov->consumed = 0; 101f87d0fbbSRusty Russell iov->i++; 102f87d0fbbSRusty Russell } 103f87d0fbbSRusty Russell } 104f87d0fbbSRusty Russell return done; 105f87d0fbbSRusty Russell } 106f87d0fbbSRusty Russell 107f87d0fbbSRusty Russell /* May reduce *len if range is shorter. */ 108f87d0fbbSRusty Russell static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len, 109f87d0fbbSRusty Russell struct vringh_range *range, 110f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, 111f87d0fbbSRusty Russell u64, struct vringh_range *)) 112f87d0fbbSRusty Russell { 113f87d0fbbSRusty Russell if (addr < range->start || addr > range->end_incl) { 114f87d0fbbSRusty Russell if (!getrange(vrh, addr, range)) 115f87d0fbbSRusty Russell return false; 116f87d0fbbSRusty Russell } 117f87d0fbbSRusty Russell BUG_ON(addr < range->start || addr > range->end_incl); 118f87d0fbbSRusty Russell 119f87d0fbbSRusty Russell /* To end of memory? */ 120f87d0fbbSRusty Russell if (unlikely(addr + *len == 0)) { 121f87d0fbbSRusty Russell if (range->end_incl == -1ULL) 122f87d0fbbSRusty Russell return true; 123f87d0fbbSRusty Russell goto truncate; 124f87d0fbbSRusty Russell } 125f87d0fbbSRusty Russell 126f87d0fbbSRusty Russell /* Otherwise, don't wrap. */ 127f87d0fbbSRusty Russell if (addr + *len < addr) { 128f87d0fbbSRusty Russell vringh_bad("Wrapping descriptor %zu@0x%llx", 129f87d0fbbSRusty Russell *len, (unsigned long long)addr); 130f87d0fbbSRusty Russell return false; 131f87d0fbbSRusty Russell } 132f87d0fbbSRusty Russell 133f87d0fbbSRusty Russell if (unlikely(addr + *len - 1 > range->end_incl)) 134f87d0fbbSRusty Russell goto truncate; 135f87d0fbbSRusty Russell return true; 136f87d0fbbSRusty Russell 137f87d0fbbSRusty Russell truncate: 138f87d0fbbSRusty Russell *len = range->end_incl + 1 - addr; 139f87d0fbbSRusty Russell return true; 140f87d0fbbSRusty Russell } 141f87d0fbbSRusty Russell 142f87d0fbbSRusty Russell static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len, 143f87d0fbbSRusty Russell struct vringh_range *range, 144f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, 145f87d0fbbSRusty Russell u64, struct vringh_range *)) 146f87d0fbbSRusty Russell { 147f87d0fbbSRusty Russell return true; 148f87d0fbbSRusty Russell } 149f87d0fbbSRusty Russell 150f87d0fbbSRusty Russell /* No reason for this code to be inline. */ 151b9f7ac8cSMichael S. Tsirkin static int move_to_indirect(const struct vringh *vrh, 152b9f7ac8cSMichael S. Tsirkin int *up_next, u16 *i, void *addr, 153f87d0fbbSRusty Russell const struct vring_desc *desc, 154f87d0fbbSRusty Russell struct vring_desc **descs, int *desc_max) 155f87d0fbbSRusty Russell { 156b9f7ac8cSMichael S. Tsirkin u32 len; 157b9f7ac8cSMichael S. Tsirkin 158f87d0fbbSRusty Russell /* Indirect tables can't have indirect. */ 159f87d0fbbSRusty Russell if (*up_next != -1) { 160f87d0fbbSRusty Russell vringh_bad("Multilevel indirect %u->%u", *up_next, *i); 161f87d0fbbSRusty Russell return -EINVAL; 162f87d0fbbSRusty Russell } 163f87d0fbbSRusty Russell 164b9f7ac8cSMichael S. Tsirkin len = vringh32_to_cpu(vrh, desc->len); 165b9f7ac8cSMichael S. Tsirkin if (unlikely(len % sizeof(struct vring_desc))) { 166f87d0fbbSRusty Russell vringh_bad("Strange indirect len %u", desc->len); 167f87d0fbbSRusty Russell return -EINVAL; 168f87d0fbbSRusty Russell } 169f87d0fbbSRusty Russell 170f87d0fbbSRusty Russell /* We will check this when we follow it! */ 171b9f7ac8cSMichael S. Tsirkin if (desc->flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) 172b9f7ac8cSMichael S. Tsirkin *up_next = vringh16_to_cpu(vrh, desc->next); 173f87d0fbbSRusty Russell else 174f87d0fbbSRusty Russell *up_next = -2; 175f87d0fbbSRusty Russell *descs = addr; 176b9f7ac8cSMichael S. Tsirkin *desc_max = len / sizeof(struct vring_desc); 177f87d0fbbSRusty Russell 178f87d0fbbSRusty Russell /* Now, start at the first indirect. */ 179f87d0fbbSRusty Russell *i = 0; 180f87d0fbbSRusty Russell return 0; 181f87d0fbbSRusty Russell } 182f87d0fbbSRusty Russell 183f87d0fbbSRusty Russell static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp) 184f87d0fbbSRusty Russell { 185f87d0fbbSRusty Russell struct kvec *new; 186f87d0fbbSRusty Russell unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2; 187f87d0fbbSRusty Russell 188f87d0fbbSRusty Russell if (new_num < 8) 189f87d0fbbSRusty Russell new_num = 8; 190f87d0fbbSRusty Russell 191f87d0fbbSRusty Russell flag = (iov->max_num & VRINGH_IOV_ALLOCATED); 192f87d0fbbSRusty Russell if (flag) 193f87d0fbbSRusty Russell new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp); 194f87d0fbbSRusty Russell else { 1956da2ec56SKees Cook new = kmalloc_array(new_num, sizeof(struct iovec), gfp); 196f87d0fbbSRusty Russell if (new) { 197f87d0fbbSRusty Russell memcpy(new, iov->iov, 198f87d0fbbSRusty Russell iov->max_num * sizeof(struct iovec)); 199f87d0fbbSRusty Russell flag = VRINGH_IOV_ALLOCATED; 200f87d0fbbSRusty Russell } 201f87d0fbbSRusty Russell } 202f87d0fbbSRusty Russell if (!new) 203f87d0fbbSRusty Russell return -ENOMEM; 204f87d0fbbSRusty Russell iov->iov = new; 205f87d0fbbSRusty Russell iov->max_num = (new_num | flag); 206f87d0fbbSRusty Russell return 0; 207f87d0fbbSRusty Russell } 208f87d0fbbSRusty Russell 209f87d0fbbSRusty Russell static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next, 210f87d0fbbSRusty Russell struct vring_desc **descs, int *desc_max) 211f87d0fbbSRusty Russell { 212f87d0fbbSRusty Russell u16 i = *up_next; 213f87d0fbbSRusty Russell 214f87d0fbbSRusty Russell *up_next = -1; 215f87d0fbbSRusty Russell *descs = vrh->vring.desc; 216f87d0fbbSRusty Russell *desc_max = vrh->vring.num; 217f87d0fbbSRusty Russell return i; 218f87d0fbbSRusty Russell } 219f87d0fbbSRusty Russell 220f87d0fbbSRusty Russell static int slow_copy(struct vringh *vrh, void *dst, const void *src, 221f87d0fbbSRusty Russell bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len, 222f87d0fbbSRusty Russell struct vringh_range *range, 223f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 224f87d0fbbSRusty Russell u64, 225f87d0fbbSRusty Russell struct vringh_range *)), 226f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 227f87d0fbbSRusty Russell u64 addr, 228f87d0fbbSRusty Russell struct vringh_range *r), 229f87d0fbbSRusty Russell struct vringh_range *range, 230f87d0fbbSRusty Russell int (*copy)(void *dst, const void *src, size_t len)) 231f87d0fbbSRusty Russell { 232f87d0fbbSRusty Russell size_t part, len = sizeof(struct vring_desc); 233f87d0fbbSRusty Russell 234f87d0fbbSRusty Russell do { 235f87d0fbbSRusty Russell u64 addr; 236f87d0fbbSRusty Russell int err; 237f87d0fbbSRusty Russell 238f87d0fbbSRusty Russell part = len; 239f87d0fbbSRusty Russell addr = (u64)(unsigned long)src - range->offset; 240f87d0fbbSRusty Russell 241f87d0fbbSRusty Russell if (!rcheck(vrh, addr, &part, range, getrange)) 242f87d0fbbSRusty Russell return -EINVAL; 243f87d0fbbSRusty Russell 244f87d0fbbSRusty Russell err = copy(dst, src, part); 245f87d0fbbSRusty Russell if (err) 246f87d0fbbSRusty Russell return err; 247f87d0fbbSRusty Russell 248f87d0fbbSRusty Russell dst += part; 249f87d0fbbSRusty Russell src += part; 250f87d0fbbSRusty Russell len -= part; 251f87d0fbbSRusty Russell } while (len); 252f87d0fbbSRusty Russell return 0; 253f87d0fbbSRusty Russell } 254f87d0fbbSRusty Russell 255f87d0fbbSRusty Russell static inline int 256f87d0fbbSRusty Russell __vringh_iov(struct vringh *vrh, u16 i, 257f87d0fbbSRusty Russell struct vringh_kiov *riov, 258f87d0fbbSRusty Russell struct vringh_kiov *wiov, 259f87d0fbbSRusty Russell bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len, 260f87d0fbbSRusty Russell struct vringh_range *range, 261f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, u64, 262f87d0fbbSRusty Russell struct vringh_range *)), 263f87d0fbbSRusty Russell bool (*getrange)(struct vringh *, u64, struct vringh_range *), 264f87d0fbbSRusty Russell gfp_t gfp, 265f87d0fbbSRusty Russell int (*copy)(void *dst, const void *src, size_t len)) 266f87d0fbbSRusty Russell { 267f87d0fbbSRusty Russell int err, count = 0, up_next, desc_max; 268f87d0fbbSRusty Russell struct vring_desc desc, *descs; 269f87d0fbbSRusty Russell struct vringh_range range = { -1ULL, 0 }, slowrange; 270f87d0fbbSRusty Russell bool slow = false; 271f87d0fbbSRusty Russell 272f87d0fbbSRusty Russell /* We start traversing vring's descriptor table. */ 273f87d0fbbSRusty Russell descs = vrh->vring.desc; 274f87d0fbbSRusty Russell desc_max = vrh->vring.num; 275f87d0fbbSRusty Russell up_next = -1; 276f87d0fbbSRusty Russell 277f87d0fbbSRusty Russell if (riov) 278f87d0fbbSRusty Russell riov->i = riov->used = 0; 279f87d0fbbSRusty Russell else if (wiov) 280f87d0fbbSRusty Russell wiov->i = wiov->used = 0; 281f87d0fbbSRusty Russell else 282f87d0fbbSRusty Russell /* You must want something! */ 283f87d0fbbSRusty Russell BUG(); 284f87d0fbbSRusty Russell 285f87d0fbbSRusty Russell for (;;) { 286f87d0fbbSRusty Russell void *addr; 287f87d0fbbSRusty Russell struct vringh_kiov *iov; 288f87d0fbbSRusty Russell size_t len; 289f87d0fbbSRusty Russell 290f87d0fbbSRusty Russell if (unlikely(slow)) 291f87d0fbbSRusty Russell err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange, 292f87d0fbbSRusty Russell &slowrange, copy); 293f87d0fbbSRusty Russell else 294f87d0fbbSRusty Russell err = copy(&desc, &descs[i], sizeof(desc)); 295f87d0fbbSRusty Russell if (unlikely(err)) 296f87d0fbbSRusty Russell goto fail; 297f87d0fbbSRusty Russell 298b9f7ac8cSMichael S. Tsirkin if (unlikely(desc.flags & 299b9f7ac8cSMichael S. Tsirkin cpu_to_vringh16(vrh, VRING_DESC_F_INDIRECT))) { 300b9f7ac8cSMichael S. Tsirkin u64 a = vringh64_to_cpu(vrh, desc.addr); 301b9f7ac8cSMichael S. Tsirkin 302f87d0fbbSRusty Russell /* Make sure it's OK, and get offset. */ 303b9f7ac8cSMichael S. Tsirkin len = vringh32_to_cpu(vrh, desc.len); 304b9f7ac8cSMichael S. Tsirkin if (!rcheck(vrh, a, &len, &range, getrange)) { 305f87d0fbbSRusty Russell err = -EINVAL; 306f87d0fbbSRusty Russell goto fail; 307f87d0fbbSRusty Russell } 308f87d0fbbSRusty Russell 309b9f7ac8cSMichael S. Tsirkin if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) { 310f87d0fbbSRusty Russell slow = true; 311f87d0fbbSRusty Russell /* We need to save this range to use offset */ 312f87d0fbbSRusty Russell slowrange = range; 313f87d0fbbSRusty Russell } 314f87d0fbbSRusty Russell 315b9f7ac8cSMichael S. Tsirkin addr = (void *)(long)(a + range.offset); 316b9f7ac8cSMichael S. Tsirkin err = move_to_indirect(vrh, &up_next, &i, addr, &desc, 317f87d0fbbSRusty Russell &descs, &desc_max); 318f87d0fbbSRusty Russell if (err) 319f87d0fbbSRusty Russell goto fail; 320f87d0fbbSRusty Russell continue; 321f87d0fbbSRusty Russell } 322f87d0fbbSRusty Russell 323f87d0fbbSRusty Russell if (count++ == vrh->vring.num) { 324f87d0fbbSRusty Russell vringh_bad("Descriptor loop in %p", descs); 325f87d0fbbSRusty Russell err = -ELOOP; 326f87d0fbbSRusty Russell goto fail; 327f87d0fbbSRusty Russell } 328f87d0fbbSRusty Russell 329b9f7ac8cSMichael S. Tsirkin if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_WRITE)) 330f87d0fbbSRusty Russell iov = wiov; 331f87d0fbbSRusty Russell else { 332f87d0fbbSRusty Russell iov = riov; 333f87d0fbbSRusty Russell if (unlikely(wiov && wiov->i)) { 334f87d0fbbSRusty Russell vringh_bad("Readable desc %p after writable", 335f87d0fbbSRusty Russell &descs[i]); 336f87d0fbbSRusty Russell err = -EINVAL; 337f87d0fbbSRusty Russell goto fail; 338f87d0fbbSRusty Russell } 339f87d0fbbSRusty Russell } 340f87d0fbbSRusty Russell 341f87d0fbbSRusty Russell if (!iov) { 342f87d0fbbSRusty Russell vringh_bad("Unexpected %s desc", 343f87d0fbbSRusty Russell !wiov ? "writable" : "readable"); 344f87d0fbbSRusty Russell err = -EPROTO; 345f87d0fbbSRusty Russell goto fail; 346f87d0fbbSRusty Russell } 347f87d0fbbSRusty Russell 348f87d0fbbSRusty Russell again: 349f87d0fbbSRusty Russell /* Make sure it's OK, and get offset. */ 350b9f7ac8cSMichael S. Tsirkin len = vringh32_to_cpu(vrh, desc.len); 351b9f7ac8cSMichael S. Tsirkin if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range, 352b9f7ac8cSMichael S. Tsirkin getrange)) { 353f87d0fbbSRusty Russell err = -EINVAL; 354f87d0fbbSRusty Russell goto fail; 355f87d0fbbSRusty Russell } 356b9f7ac8cSMichael S. Tsirkin addr = (void *)(unsigned long)(vringh64_to_cpu(vrh, desc.addr) + 357b9f7ac8cSMichael S. Tsirkin range.offset); 358f87d0fbbSRusty Russell 359f87d0fbbSRusty Russell if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) { 360f87d0fbbSRusty Russell err = resize_iovec(iov, gfp); 361f87d0fbbSRusty Russell if (err) 362f87d0fbbSRusty Russell goto fail; 363f87d0fbbSRusty Russell } 364f87d0fbbSRusty Russell 365f87d0fbbSRusty Russell iov->iov[iov->used].iov_base = addr; 366f87d0fbbSRusty Russell iov->iov[iov->used].iov_len = len; 367f87d0fbbSRusty Russell iov->used++; 368f87d0fbbSRusty Russell 369b9f7ac8cSMichael S. Tsirkin if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) { 370b9f7ac8cSMichael S. Tsirkin desc.len = cpu_to_vringh32(vrh, 371b9f7ac8cSMichael S. Tsirkin vringh32_to_cpu(vrh, desc.len) - len); 372b9f7ac8cSMichael S. Tsirkin desc.addr = cpu_to_vringh64(vrh, 373b9f7ac8cSMichael S. Tsirkin vringh64_to_cpu(vrh, desc.addr) + len); 374f87d0fbbSRusty Russell goto again; 375f87d0fbbSRusty Russell } 376f87d0fbbSRusty Russell 377b9f7ac8cSMichael S. Tsirkin if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) { 378b9f7ac8cSMichael S. Tsirkin i = vringh16_to_cpu(vrh, desc.next); 379f87d0fbbSRusty Russell } else { 380f87d0fbbSRusty Russell /* Just in case we need to finish traversing above. */ 381f87d0fbbSRusty Russell if (unlikely(up_next > 0)) { 382f87d0fbbSRusty Russell i = return_from_indirect(vrh, &up_next, 383f87d0fbbSRusty Russell &descs, &desc_max); 384f87d0fbbSRusty Russell slow = false; 385f87d0fbbSRusty Russell } else 386f87d0fbbSRusty Russell break; 387f87d0fbbSRusty Russell } 388f87d0fbbSRusty Russell 389f87d0fbbSRusty Russell if (i >= desc_max) { 390f87d0fbbSRusty Russell vringh_bad("Chained index %u > %u", i, desc_max); 391f87d0fbbSRusty Russell err = -EINVAL; 392f87d0fbbSRusty Russell goto fail; 393f87d0fbbSRusty Russell } 394f87d0fbbSRusty Russell } 395f87d0fbbSRusty Russell 396f87d0fbbSRusty Russell return 0; 397f87d0fbbSRusty Russell 398f87d0fbbSRusty Russell fail: 399f87d0fbbSRusty Russell return err; 400f87d0fbbSRusty Russell } 401f87d0fbbSRusty Russell 402f87d0fbbSRusty Russell static inline int __vringh_complete(struct vringh *vrh, 403f87d0fbbSRusty Russell const struct vring_used_elem *used, 404f87d0fbbSRusty Russell unsigned int num_used, 405b9f7ac8cSMichael S. Tsirkin int (*putu16)(const struct vringh *vrh, 406b9f7ac8cSMichael S. Tsirkin __virtio16 *p, u16 val), 407f87d0fbbSRusty Russell int (*putused)(struct vring_used_elem *dst, 408f87d0fbbSRusty Russell const struct vring_used_elem 409f87d0fbbSRusty Russell *src, unsigned num)) 410f87d0fbbSRusty Russell { 411f87d0fbbSRusty Russell struct vring_used *used_ring; 412f87d0fbbSRusty Russell int err; 413f87d0fbbSRusty Russell u16 used_idx, off; 414f87d0fbbSRusty Russell 415f87d0fbbSRusty Russell used_ring = vrh->vring.used; 416f87d0fbbSRusty Russell used_idx = vrh->last_used_idx + vrh->completed; 417f87d0fbbSRusty Russell 418f87d0fbbSRusty Russell off = used_idx % vrh->vring.num; 419f87d0fbbSRusty Russell 420f87d0fbbSRusty Russell /* Compiler knows num_used == 1 sometimes, hence extra check */ 421f87d0fbbSRusty Russell if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) { 422f87d0fbbSRusty Russell u16 part = vrh->vring.num - off; 423f87d0fbbSRusty Russell err = putused(&used_ring->ring[off], used, part); 424f87d0fbbSRusty Russell if (!err) 425f87d0fbbSRusty Russell err = putused(&used_ring->ring[0], used + part, 426f87d0fbbSRusty Russell num_used - part); 427f87d0fbbSRusty Russell } else 428f87d0fbbSRusty Russell err = putused(&used_ring->ring[off], used, num_used); 429f87d0fbbSRusty Russell 430f87d0fbbSRusty Russell if (err) { 431f87d0fbbSRusty Russell vringh_bad("Failed to write %u used entries %u at %p", 432f87d0fbbSRusty Russell num_used, off, &used_ring->ring[off]); 433f87d0fbbSRusty Russell return err; 434f87d0fbbSRusty Russell } 435f87d0fbbSRusty Russell 436f87d0fbbSRusty Russell /* Make sure buffer is written before we update index. */ 437f87d0fbbSRusty Russell virtio_wmb(vrh->weak_barriers); 438f87d0fbbSRusty Russell 439b9f7ac8cSMichael S. Tsirkin err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used); 440f87d0fbbSRusty Russell if (err) { 441f87d0fbbSRusty Russell vringh_bad("Failed to update used index at %p", 442f87d0fbbSRusty Russell &vrh->vring.used->idx); 443f87d0fbbSRusty Russell return err; 444f87d0fbbSRusty Russell } 445f87d0fbbSRusty Russell 446f87d0fbbSRusty Russell vrh->completed += num_used; 447f87d0fbbSRusty Russell return 0; 448f87d0fbbSRusty Russell } 449f87d0fbbSRusty Russell 450f87d0fbbSRusty Russell 451f87d0fbbSRusty Russell static inline int __vringh_need_notify(struct vringh *vrh, 452b9f7ac8cSMichael S. Tsirkin int (*getu16)(const struct vringh *vrh, 453b9f7ac8cSMichael S. Tsirkin u16 *val, 454b9f7ac8cSMichael S. Tsirkin const __virtio16 *p)) 455f87d0fbbSRusty Russell { 456f87d0fbbSRusty Russell bool notify; 457f87d0fbbSRusty Russell u16 used_event; 458f87d0fbbSRusty Russell int err; 459f87d0fbbSRusty Russell 460f87d0fbbSRusty Russell /* Flush out used index update. This is paired with the 461f87d0fbbSRusty Russell * barrier that the Guest executes when enabling 462f87d0fbbSRusty Russell * interrupts. */ 463f87d0fbbSRusty Russell virtio_mb(vrh->weak_barriers); 464f87d0fbbSRusty Russell 465f87d0fbbSRusty Russell /* Old-style, without event indices. */ 466f87d0fbbSRusty Russell if (!vrh->event_indices) { 467f87d0fbbSRusty Russell u16 flags; 468b9f7ac8cSMichael S. Tsirkin err = getu16(vrh, &flags, &vrh->vring.avail->flags); 469f87d0fbbSRusty Russell if (err) { 470f87d0fbbSRusty Russell vringh_bad("Failed to get flags at %p", 471f87d0fbbSRusty Russell &vrh->vring.avail->flags); 472f87d0fbbSRusty Russell return err; 473f87d0fbbSRusty Russell } 474f87d0fbbSRusty Russell return (!(flags & VRING_AVAIL_F_NO_INTERRUPT)); 475f87d0fbbSRusty Russell } 476f87d0fbbSRusty Russell 477f87d0fbbSRusty Russell /* Modern: we know when other side wants to know. */ 478b9f7ac8cSMichael S. Tsirkin err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring)); 479f87d0fbbSRusty Russell if (err) { 480f87d0fbbSRusty Russell vringh_bad("Failed to get used event idx at %p", 481f87d0fbbSRusty Russell &vring_used_event(&vrh->vring)); 482f87d0fbbSRusty Russell return err; 483f87d0fbbSRusty Russell } 484f87d0fbbSRusty Russell 485f87d0fbbSRusty Russell /* Just in case we added so many that we wrap. */ 486f87d0fbbSRusty Russell if (unlikely(vrh->completed > 0xffff)) 487f87d0fbbSRusty Russell notify = true; 488f87d0fbbSRusty Russell else 489f87d0fbbSRusty Russell notify = vring_need_event(used_event, 490f87d0fbbSRusty Russell vrh->last_used_idx + vrh->completed, 491f87d0fbbSRusty Russell vrh->last_used_idx); 492f87d0fbbSRusty Russell 493f87d0fbbSRusty Russell vrh->last_used_idx += vrh->completed; 494f87d0fbbSRusty Russell vrh->completed = 0; 495f87d0fbbSRusty Russell return notify; 496f87d0fbbSRusty Russell } 497f87d0fbbSRusty Russell 498f87d0fbbSRusty Russell static inline bool __vringh_notify_enable(struct vringh *vrh, 499b9f7ac8cSMichael S. Tsirkin int (*getu16)(const struct vringh *vrh, 500b9f7ac8cSMichael S. Tsirkin u16 *val, const __virtio16 *p), 501b9f7ac8cSMichael S. Tsirkin int (*putu16)(const struct vringh *vrh, 502b9f7ac8cSMichael S. Tsirkin __virtio16 *p, u16 val)) 503f87d0fbbSRusty Russell { 504f87d0fbbSRusty Russell u16 avail; 505f87d0fbbSRusty Russell 506f87d0fbbSRusty Russell if (!vrh->event_indices) { 507f87d0fbbSRusty Russell /* Old-school; update flags. */ 508b9f7ac8cSMichael S. Tsirkin if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) { 509f87d0fbbSRusty Russell vringh_bad("Clearing used flags %p", 510f87d0fbbSRusty Russell &vrh->vring.used->flags); 511f87d0fbbSRusty Russell return true; 512f87d0fbbSRusty Russell } 513f87d0fbbSRusty Russell } else { 514b9f7ac8cSMichael S. Tsirkin if (putu16(vrh, &vring_avail_event(&vrh->vring), 515f87d0fbbSRusty Russell vrh->last_avail_idx) != 0) { 516f87d0fbbSRusty Russell vringh_bad("Updating avail event index %p", 517f87d0fbbSRusty Russell &vring_avail_event(&vrh->vring)); 518f87d0fbbSRusty Russell return true; 519f87d0fbbSRusty Russell } 520f87d0fbbSRusty Russell } 521f87d0fbbSRusty Russell 522f87d0fbbSRusty Russell /* They could have slipped one in as we were doing that: make 523f87d0fbbSRusty Russell * sure it's written, then check again. */ 524f87d0fbbSRusty Russell virtio_mb(vrh->weak_barriers); 525f87d0fbbSRusty Russell 526b9f7ac8cSMichael S. Tsirkin if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) { 527f87d0fbbSRusty Russell vringh_bad("Failed to check avail idx at %p", 528f87d0fbbSRusty Russell &vrh->vring.avail->idx); 529f87d0fbbSRusty Russell return true; 530f87d0fbbSRusty Russell } 531f87d0fbbSRusty Russell 532f87d0fbbSRusty Russell /* This is unlikely, so we just leave notifications enabled 533f87d0fbbSRusty Russell * (if we're using event_indices, we'll only get one 534f87d0fbbSRusty Russell * notification anyway). */ 535f87d0fbbSRusty Russell return avail == vrh->last_avail_idx; 536f87d0fbbSRusty Russell } 537f87d0fbbSRusty Russell 538f87d0fbbSRusty Russell static inline void __vringh_notify_disable(struct vringh *vrh, 539b9f7ac8cSMichael S. Tsirkin int (*putu16)(const struct vringh *vrh, 540b9f7ac8cSMichael S. Tsirkin __virtio16 *p, u16 val)) 541f87d0fbbSRusty Russell { 542f87d0fbbSRusty Russell if (!vrh->event_indices) { 543f87d0fbbSRusty Russell /* Old-school; update flags. */ 544b9f7ac8cSMichael S. Tsirkin if (putu16(vrh, &vrh->vring.used->flags, 545b9f7ac8cSMichael S. Tsirkin VRING_USED_F_NO_NOTIFY)) { 546f87d0fbbSRusty Russell vringh_bad("Setting used flags %p", 547f87d0fbbSRusty Russell &vrh->vring.used->flags); 548f87d0fbbSRusty Russell } 549f87d0fbbSRusty Russell } 550f87d0fbbSRusty Russell } 551f87d0fbbSRusty Russell 552f87d0fbbSRusty Russell /* Userspace access helpers: in this case, addresses are really userspace. */ 553b9f7ac8cSMichael S. Tsirkin static inline int getu16_user(const struct vringh *vrh, u16 *val, const __virtio16 *p) 554f87d0fbbSRusty Russell { 555b9f7ac8cSMichael S. Tsirkin __virtio16 v = 0; 556b9f7ac8cSMichael S. Tsirkin int rc = get_user(v, (__force __virtio16 __user *)p); 557b9f7ac8cSMichael S. Tsirkin *val = vringh16_to_cpu(vrh, v); 558b9f7ac8cSMichael S. Tsirkin return rc; 559f87d0fbbSRusty Russell } 560f87d0fbbSRusty Russell 561b9f7ac8cSMichael S. Tsirkin static inline int putu16_user(const struct vringh *vrh, __virtio16 *p, u16 val) 562f87d0fbbSRusty Russell { 563b9f7ac8cSMichael S. Tsirkin __virtio16 v = cpu_to_vringh16(vrh, val); 564b9f7ac8cSMichael S. Tsirkin return put_user(v, (__force __virtio16 __user *)p); 565f87d0fbbSRusty Russell } 566f87d0fbbSRusty Russell 567f87d0fbbSRusty Russell static inline int copydesc_user(void *dst, const void *src, size_t len) 568f87d0fbbSRusty Russell { 569f87d0fbbSRusty Russell return copy_from_user(dst, (__force void __user *)src, len) ? 570f87d0fbbSRusty Russell -EFAULT : 0; 571f87d0fbbSRusty Russell } 572f87d0fbbSRusty Russell 573f87d0fbbSRusty Russell static inline int putused_user(struct vring_used_elem *dst, 574f87d0fbbSRusty Russell const struct vring_used_elem *src, 575f87d0fbbSRusty Russell unsigned int num) 576f87d0fbbSRusty Russell { 577f87d0fbbSRusty Russell return copy_to_user((__force void __user *)dst, src, 578f87d0fbbSRusty Russell sizeof(*dst) * num) ? -EFAULT : 0; 579f87d0fbbSRusty Russell } 580f87d0fbbSRusty Russell 581f87d0fbbSRusty Russell static inline int xfer_from_user(void *src, void *dst, size_t len) 582f87d0fbbSRusty Russell { 583f87d0fbbSRusty Russell return copy_from_user(dst, (__force void __user *)src, len) ? 584f87d0fbbSRusty Russell -EFAULT : 0; 585f87d0fbbSRusty Russell } 586f87d0fbbSRusty Russell 587f87d0fbbSRusty Russell static inline int xfer_to_user(void *dst, void *src, size_t len) 588f87d0fbbSRusty Russell { 589f87d0fbbSRusty Russell return copy_to_user((__force void __user *)dst, src, len) ? 590f87d0fbbSRusty Russell -EFAULT : 0; 591f87d0fbbSRusty Russell } 592f87d0fbbSRusty Russell 593f87d0fbbSRusty Russell /** 594f87d0fbbSRusty Russell * vringh_init_user - initialize a vringh for a userspace vring. 595f87d0fbbSRusty Russell * @vrh: the vringh to initialize. 596f87d0fbbSRusty Russell * @features: the feature bits for this ring. 597f87d0fbbSRusty Russell * @num: the number of elements. 598f87d0fbbSRusty Russell * @weak_barriers: true if we only need memory barriers, not I/O. 599f87d0fbbSRusty Russell * @desc: the userpace descriptor pointer. 600f87d0fbbSRusty Russell * @avail: the userpace avail pointer. 601f87d0fbbSRusty Russell * @used: the userpace used pointer. 602f87d0fbbSRusty Russell * 603f87d0fbbSRusty Russell * Returns an error if num is invalid: you should check pointers 604f87d0fbbSRusty Russell * yourself! 605f87d0fbbSRusty Russell */ 606b97a8a90SMichael S. Tsirkin int vringh_init_user(struct vringh *vrh, u64 features, 607f87d0fbbSRusty Russell unsigned int num, bool weak_barriers, 608f87d0fbbSRusty Russell struct vring_desc __user *desc, 609f87d0fbbSRusty Russell struct vring_avail __user *avail, 610f87d0fbbSRusty Russell struct vring_used __user *used) 611f87d0fbbSRusty Russell { 612f87d0fbbSRusty Russell /* Sane power of 2 please! */ 613f87d0fbbSRusty Russell if (!num || num > 0xffff || (num & (num - 1))) { 614f87d0fbbSRusty Russell vringh_bad("Bad ring size %u", num); 615f87d0fbbSRusty Russell return -EINVAL; 616f87d0fbbSRusty Russell } 617f87d0fbbSRusty Russell 618b9f7ac8cSMichael S. Tsirkin vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1)); 619f87d0fbbSRusty Russell vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX)); 620f87d0fbbSRusty Russell vrh->weak_barriers = weak_barriers; 621f87d0fbbSRusty Russell vrh->completed = 0; 622f87d0fbbSRusty Russell vrh->last_avail_idx = 0; 623f87d0fbbSRusty Russell vrh->last_used_idx = 0; 624f87d0fbbSRusty Russell vrh->vring.num = num; 625f87d0fbbSRusty Russell /* vring expects kernel addresses, but only used via accessors. */ 626f87d0fbbSRusty Russell vrh->vring.desc = (__force struct vring_desc *)desc; 627f87d0fbbSRusty Russell vrh->vring.avail = (__force struct vring_avail *)avail; 628f87d0fbbSRusty Russell vrh->vring.used = (__force struct vring_used *)used; 629f87d0fbbSRusty Russell return 0; 630f87d0fbbSRusty Russell } 631f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_init_user); 632f87d0fbbSRusty Russell 633f87d0fbbSRusty Russell /** 634f87d0fbbSRusty Russell * vringh_getdesc_user - get next available descriptor from userspace ring. 635f87d0fbbSRusty Russell * @vrh: the userspace vring. 636f87d0fbbSRusty Russell * @riov: where to put the readable descriptors (or NULL) 637f87d0fbbSRusty Russell * @wiov: where to put the writable descriptors (or NULL) 638f87d0fbbSRusty Russell * @getrange: function to call to check ranges. 639f87d0fbbSRusty Russell * @head: head index we received, for passing to vringh_complete_user(). 640f87d0fbbSRusty Russell * 641f87d0fbbSRusty Russell * Returns 0 if there was no descriptor, 1 if there was, or -errno. 642f87d0fbbSRusty Russell * 643f87d0fbbSRusty Russell * Note that on error return, you can tell the difference between an 644f87d0fbbSRusty Russell * invalid ring and a single invalid descriptor: in the former case, 645f87d0fbbSRusty Russell * *head will be vrh->vring.num. You may be able to ignore an invalid 646f87d0fbbSRusty Russell * descriptor, but there's not much you can do with an invalid ring. 647f87d0fbbSRusty Russell * 648f87d0fbbSRusty Russell * Note that you may need to clean up riov and wiov, even on error! 649f87d0fbbSRusty Russell */ 650f87d0fbbSRusty Russell int vringh_getdesc_user(struct vringh *vrh, 651f87d0fbbSRusty Russell struct vringh_iov *riov, 652f87d0fbbSRusty Russell struct vringh_iov *wiov, 653f87d0fbbSRusty Russell bool (*getrange)(struct vringh *vrh, 654f87d0fbbSRusty Russell u64 addr, struct vringh_range *r), 655f87d0fbbSRusty Russell u16 *head) 656f87d0fbbSRusty Russell { 657f87d0fbbSRusty Russell int err; 658f87d0fbbSRusty Russell 659f87d0fbbSRusty Russell *head = vrh->vring.num; 660f87d0fbbSRusty Russell err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx); 661f87d0fbbSRusty Russell if (err < 0) 662f87d0fbbSRusty Russell return err; 663f87d0fbbSRusty Russell 664f87d0fbbSRusty Russell /* Empty... */ 665f87d0fbbSRusty Russell if (err == vrh->vring.num) 666f87d0fbbSRusty Russell return 0; 667f87d0fbbSRusty Russell 668f87d0fbbSRusty Russell /* We need the layouts to be the identical for this to work */ 669f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov)); 670f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) != 671f87d0fbbSRusty Russell offsetof(struct vringh_iov, iov)); 672f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, i) != 673f87d0fbbSRusty Russell offsetof(struct vringh_iov, i)); 674f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, used) != 675f87d0fbbSRusty Russell offsetof(struct vringh_iov, used)); 676f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) != 677f87d0fbbSRusty Russell offsetof(struct vringh_iov, max_num)); 678f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); 679f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct iovec, iov_base) != 680f87d0fbbSRusty Russell offsetof(struct kvec, iov_base)); 681f87d0fbbSRusty Russell BUILD_BUG_ON(offsetof(struct iovec, iov_len) != 682f87d0fbbSRusty Russell offsetof(struct kvec, iov_len)); 683f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base) 684f87d0fbbSRusty Russell != sizeof(((struct kvec *)NULL)->iov_base)); 685f87d0fbbSRusty Russell BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len) 686f87d0fbbSRusty Russell != sizeof(((struct kvec *)NULL)->iov_len)); 687f87d0fbbSRusty Russell 688f87d0fbbSRusty Russell *head = err; 689f87d0fbbSRusty Russell err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov, 690f87d0fbbSRusty Russell (struct vringh_kiov *)wiov, 691f87d0fbbSRusty Russell range_check, getrange, GFP_KERNEL, copydesc_user); 692f87d0fbbSRusty Russell if (err) 693f87d0fbbSRusty Russell return err; 694f87d0fbbSRusty Russell 695f87d0fbbSRusty Russell return 1; 696f87d0fbbSRusty Russell } 697f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_getdesc_user); 698f87d0fbbSRusty Russell 699f87d0fbbSRusty Russell /** 700f87d0fbbSRusty Russell * vringh_iov_pull_user - copy bytes from vring_iov. 701f87d0fbbSRusty Russell * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume) 702f87d0fbbSRusty Russell * @dst: the place to copy. 703f87d0fbbSRusty Russell * @len: the maximum length to copy. 704f87d0fbbSRusty Russell * 705f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 706f87d0fbbSRusty Russell */ 707f87d0fbbSRusty Russell ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len) 708f87d0fbbSRusty Russell { 709f87d0fbbSRusty Russell return vringh_iov_xfer((struct vringh_kiov *)riov, 710f87d0fbbSRusty Russell dst, len, xfer_from_user); 711f87d0fbbSRusty Russell } 712f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_pull_user); 713f87d0fbbSRusty Russell 714f87d0fbbSRusty Russell /** 715f87d0fbbSRusty Russell * vringh_iov_push_user - copy bytes into vring_iov. 716f87d0fbbSRusty Russell * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume) 717f87d0fbbSRusty Russell * @dst: the place to copy. 718f87d0fbbSRusty Russell * @len: the maximum length to copy. 719f87d0fbbSRusty Russell * 720f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 721f87d0fbbSRusty Russell */ 722f87d0fbbSRusty Russell ssize_t vringh_iov_push_user(struct vringh_iov *wiov, 723f87d0fbbSRusty Russell const void *src, size_t len) 724f87d0fbbSRusty Russell { 725f87d0fbbSRusty Russell return vringh_iov_xfer((struct vringh_kiov *)wiov, 726f87d0fbbSRusty Russell (void *)src, len, xfer_to_user); 727f87d0fbbSRusty Russell } 728f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_push_user); 729f87d0fbbSRusty Russell 730f87d0fbbSRusty Russell /** 731f87d0fbbSRusty Russell * vringh_abandon_user - we've decided not to handle the descriptor(s). 732f87d0fbbSRusty Russell * @vrh: the vring. 733f87d0fbbSRusty Russell * @num: the number of descriptors to put back (ie. num 734f87d0fbbSRusty Russell * vringh_get_user() to undo). 735f87d0fbbSRusty Russell * 736f87d0fbbSRusty Russell * The next vringh_get_user() will return the old descriptor(s) again. 737f87d0fbbSRusty Russell */ 738f87d0fbbSRusty Russell void vringh_abandon_user(struct vringh *vrh, unsigned int num) 739f87d0fbbSRusty Russell { 740f87d0fbbSRusty Russell /* We only update vring_avail_event(vr) when we want to be notified, 741f87d0fbbSRusty Russell * so we haven't changed that yet. */ 742f87d0fbbSRusty Russell vrh->last_avail_idx -= num; 743f87d0fbbSRusty Russell } 744f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_abandon_user); 745f87d0fbbSRusty Russell 746f87d0fbbSRusty Russell /** 747f87d0fbbSRusty Russell * vringh_complete_user - we've finished with descriptor, publish it. 748f87d0fbbSRusty Russell * @vrh: the vring. 749f87d0fbbSRusty Russell * @head: the head as filled in by vringh_getdesc_user. 750f87d0fbbSRusty Russell * @len: the length of data we have written. 751f87d0fbbSRusty Russell * 752f87d0fbbSRusty Russell * You should check vringh_need_notify_user() after one or more calls 753f87d0fbbSRusty Russell * to this function. 754f87d0fbbSRusty Russell */ 755f87d0fbbSRusty Russell int vringh_complete_user(struct vringh *vrh, u16 head, u32 len) 756f87d0fbbSRusty Russell { 757f87d0fbbSRusty Russell struct vring_used_elem used; 758f87d0fbbSRusty Russell 759b9f7ac8cSMichael S. Tsirkin used.id = cpu_to_vringh32(vrh, head); 760b9f7ac8cSMichael S. Tsirkin used.len = cpu_to_vringh32(vrh, len); 761f87d0fbbSRusty Russell return __vringh_complete(vrh, &used, 1, putu16_user, putused_user); 762f87d0fbbSRusty Russell } 763f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_user); 764f87d0fbbSRusty Russell 765f87d0fbbSRusty Russell /** 766f87d0fbbSRusty Russell * vringh_complete_multi_user - we've finished with many descriptors. 767f87d0fbbSRusty Russell * @vrh: the vring. 768f87d0fbbSRusty Russell * @used: the head, length pairs. 769f87d0fbbSRusty Russell * @num_used: the number of used elements. 770f87d0fbbSRusty Russell * 771f87d0fbbSRusty Russell * You should check vringh_need_notify_user() after one or more calls 772f87d0fbbSRusty Russell * to this function. 773f87d0fbbSRusty Russell */ 774f87d0fbbSRusty Russell int vringh_complete_multi_user(struct vringh *vrh, 775f87d0fbbSRusty Russell const struct vring_used_elem used[], 776f87d0fbbSRusty Russell unsigned num_used) 777f87d0fbbSRusty Russell { 778f87d0fbbSRusty Russell return __vringh_complete(vrh, used, num_used, 779f87d0fbbSRusty Russell putu16_user, putused_user); 780f87d0fbbSRusty Russell } 781f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_multi_user); 782f87d0fbbSRusty Russell 783f87d0fbbSRusty Russell /** 784f87d0fbbSRusty Russell * vringh_notify_enable_user - we want to know if something changes. 785f87d0fbbSRusty Russell * @vrh: the vring. 786f87d0fbbSRusty Russell * 787f87d0fbbSRusty Russell * This always enables notifications, but returns false if there are 788f87d0fbbSRusty Russell * now more buffers available in the vring. 789f87d0fbbSRusty Russell */ 790f87d0fbbSRusty Russell bool vringh_notify_enable_user(struct vringh *vrh) 791f87d0fbbSRusty Russell { 792f87d0fbbSRusty Russell return __vringh_notify_enable(vrh, getu16_user, putu16_user); 793f87d0fbbSRusty Russell } 794f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_enable_user); 795f87d0fbbSRusty Russell 796f87d0fbbSRusty Russell /** 797f87d0fbbSRusty Russell * vringh_notify_disable_user - don't tell us if something changes. 798f87d0fbbSRusty Russell * @vrh: the vring. 799f87d0fbbSRusty Russell * 800f87d0fbbSRusty Russell * This is our normal running state: we disable and then only enable when 801f87d0fbbSRusty Russell * we're going to sleep. 802f87d0fbbSRusty Russell */ 803f87d0fbbSRusty Russell void vringh_notify_disable_user(struct vringh *vrh) 804f87d0fbbSRusty Russell { 805f87d0fbbSRusty Russell __vringh_notify_disable(vrh, putu16_user); 806f87d0fbbSRusty Russell } 807f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_disable_user); 808f87d0fbbSRusty Russell 809f87d0fbbSRusty Russell /** 810f87d0fbbSRusty Russell * vringh_need_notify_user - must we tell the other side about used buffers? 811f87d0fbbSRusty Russell * @vrh: the vring we've called vringh_complete_user() on. 812f87d0fbbSRusty Russell * 813f87d0fbbSRusty Russell * Returns -errno or 0 if we don't need to tell the other side, 1 if we do. 814f87d0fbbSRusty Russell */ 815f87d0fbbSRusty Russell int vringh_need_notify_user(struct vringh *vrh) 816f87d0fbbSRusty Russell { 817f87d0fbbSRusty Russell return __vringh_need_notify(vrh, getu16_user); 818f87d0fbbSRusty Russell } 819f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_need_notify_user); 820f87d0fbbSRusty Russell 821f87d0fbbSRusty Russell /* Kernelspace access helpers. */ 822b9f7ac8cSMichael S. Tsirkin static inline int getu16_kern(const struct vringh *vrh, 823b9f7ac8cSMichael S. Tsirkin u16 *val, const __virtio16 *p) 824f87d0fbbSRusty Russell { 8259d1b972fSMark Rutland *val = vringh16_to_cpu(vrh, READ_ONCE(*p)); 826f87d0fbbSRusty Russell return 0; 827f87d0fbbSRusty Russell } 828f87d0fbbSRusty Russell 829b9f7ac8cSMichael S. Tsirkin static inline int putu16_kern(const struct vringh *vrh, __virtio16 *p, u16 val) 830f87d0fbbSRusty Russell { 8319d1b972fSMark Rutland WRITE_ONCE(*p, cpu_to_vringh16(vrh, val)); 832f87d0fbbSRusty Russell return 0; 833f87d0fbbSRusty Russell } 834f87d0fbbSRusty Russell 835f87d0fbbSRusty Russell static inline int copydesc_kern(void *dst, const void *src, size_t len) 836f87d0fbbSRusty Russell { 837f87d0fbbSRusty Russell memcpy(dst, src, len); 838f87d0fbbSRusty Russell return 0; 839f87d0fbbSRusty Russell } 840f87d0fbbSRusty Russell 841f87d0fbbSRusty Russell static inline int putused_kern(struct vring_used_elem *dst, 842f87d0fbbSRusty Russell const struct vring_used_elem *src, 843f87d0fbbSRusty Russell unsigned int num) 844f87d0fbbSRusty Russell { 845f87d0fbbSRusty Russell memcpy(dst, src, num * sizeof(*dst)); 846f87d0fbbSRusty Russell return 0; 847f87d0fbbSRusty Russell } 848f87d0fbbSRusty Russell 849f87d0fbbSRusty Russell static inline int xfer_kern(void *src, void *dst, size_t len) 850f87d0fbbSRusty Russell { 851f87d0fbbSRusty Russell memcpy(dst, src, len); 852f87d0fbbSRusty Russell return 0; 853f87d0fbbSRusty Russell } 854f87d0fbbSRusty Russell 855f87d0fbbSRusty Russell /** 856f87d0fbbSRusty Russell * vringh_init_kern - initialize a vringh for a kernelspace vring. 857f87d0fbbSRusty Russell * @vrh: the vringh to initialize. 858f87d0fbbSRusty Russell * @features: the feature bits for this ring. 859f87d0fbbSRusty Russell * @num: the number of elements. 860f87d0fbbSRusty Russell * @weak_barriers: true if we only need memory barriers, not I/O. 861f87d0fbbSRusty Russell * @desc: the userpace descriptor pointer. 862f87d0fbbSRusty Russell * @avail: the userpace avail pointer. 863f87d0fbbSRusty Russell * @used: the userpace used pointer. 864f87d0fbbSRusty Russell * 865f87d0fbbSRusty Russell * Returns an error if num is invalid. 866f87d0fbbSRusty Russell */ 867b97a8a90SMichael S. Tsirkin int vringh_init_kern(struct vringh *vrh, u64 features, 868f87d0fbbSRusty Russell unsigned int num, bool weak_barriers, 869f87d0fbbSRusty Russell struct vring_desc *desc, 870f87d0fbbSRusty Russell struct vring_avail *avail, 871f87d0fbbSRusty Russell struct vring_used *used) 872f87d0fbbSRusty Russell { 873f87d0fbbSRusty Russell /* Sane power of 2 please! */ 874f87d0fbbSRusty Russell if (!num || num > 0xffff || (num & (num - 1))) { 875f87d0fbbSRusty Russell vringh_bad("Bad ring size %u", num); 876f87d0fbbSRusty Russell return -EINVAL; 877f87d0fbbSRusty Russell } 878f87d0fbbSRusty Russell 879b9f7ac8cSMichael S. Tsirkin vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1)); 880f87d0fbbSRusty Russell vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX)); 881f87d0fbbSRusty Russell vrh->weak_barriers = weak_barriers; 882f87d0fbbSRusty Russell vrh->completed = 0; 883f87d0fbbSRusty Russell vrh->last_avail_idx = 0; 884f87d0fbbSRusty Russell vrh->last_used_idx = 0; 885f87d0fbbSRusty Russell vrh->vring.num = num; 886f87d0fbbSRusty Russell vrh->vring.desc = desc; 887f87d0fbbSRusty Russell vrh->vring.avail = avail; 888f87d0fbbSRusty Russell vrh->vring.used = used; 889f87d0fbbSRusty Russell return 0; 890f87d0fbbSRusty Russell } 891f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_init_kern); 892f87d0fbbSRusty Russell 893f87d0fbbSRusty Russell /** 894f87d0fbbSRusty Russell * vringh_getdesc_kern - get next available descriptor from kernelspace ring. 895f87d0fbbSRusty Russell * @vrh: the kernelspace vring. 896f87d0fbbSRusty Russell * @riov: where to put the readable descriptors (or NULL) 897f87d0fbbSRusty Russell * @wiov: where to put the writable descriptors (or NULL) 898f87d0fbbSRusty Russell * @head: head index we received, for passing to vringh_complete_kern(). 899f87d0fbbSRusty Russell * @gfp: flags for allocating larger riov/wiov. 900f87d0fbbSRusty Russell * 901f87d0fbbSRusty Russell * Returns 0 if there was no descriptor, 1 if there was, or -errno. 902f87d0fbbSRusty Russell * 903f87d0fbbSRusty Russell * Note that on error return, you can tell the difference between an 904f87d0fbbSRusty Russell * invalid ring and a single invalid descriptor: in the former case, 905f87d0fbbSRusty Russell * *head will be vrh->vring.num. You may be able to ignore an invalid 906f87d0fbbSRusty Russell * descriptor, but there's not much you can do with an invalid ring. 907f87d0fbbSRusty Russell * 908f87d0fbbSRusty Russell * Note that you may need to clean up riov and wiov, even on error! 909f87d0fbbSRusty Russell */ 910f87d0fbbSRusty Russell int vringh_getdesc_kern(struct vringh *vrh, 911f87d0fbbSRusty Russell struct vringh_kiov *riov, 912f87d0fbbSRusty Russell struct vringh_kiov *wiov, 913f87d0fbbSRusty Russell u16 *head, 914f87d0fbbSRusty Russell gfp_t gfp) 915f87d0fbbSRusty Russell { 916f87d0fbbSRusty Russell int err; 917f87d0fbbSRusty Russell 918f87d0fbbSRusty Russell err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx); 919f87d0fbbSRusty Russell if (err < 0) 920f87d0fbbSRusty Russell return err; 921f87d0fbbSRusty Russell 922f87d0fbbSRusty Russell /* Empty... */ 923f87d0fbbSRusty Russell if (err == vrh->vring.num) 924f87d0fbbSRusty Russell return 0; 925f87d0fbbSRusty Russell 926f87d0fbbSRusty Russell *head = err; 927f87d0fbbSRusty Russell err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL, 928f87d0fbbSRusty Russell gfp, copydesc_kern); 929f87d0fbbSRusty Russell if (err) 930f87d0fbbSRusty Russell return err; 931f87d0fbbSRusty Russell 932f87d0fbbSRusty Russell return 1; 933f87d0fbbSRusty Russell } 934f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_getdesc_kern); 935f87d0fbbSRusty Russell 936f87d0fbbSRusty Russell /** 937f87d0fbbSRusty Russell * vringh_iov_pull_kern - copy bytes from vring_iov. 938f87d0fbbSRusty Russell * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume) 939f87d0fbbSRusty Russell * @dst: the place to copy. 940f87d0fbbSRusty Russell * @len: the maximum length to copy. 941f87d0fbbSRusty Russell * 942f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 943f87d0fbbSRusty Russell */ 944f87d0fbbSRusty Russell ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len) 945f87d0fbbSRusty Russell { 946f87d0fbbSRusty Russell return vringh_iov_xfer(riov, dst, len, xfer_kern); 947f87d0fbbSRusty Russell } 948f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_pull_kern); 949f87d0fbbSRusty Russell 950f87d0fbbSRusty Russell /** 951f87d0fbbSRusty Russell * vringh_iov_push_kern - copy bytes into vring_iov. 952f87d0fbbSRusty Russell * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume) 953f87d0fbbSRusty Russell * @dst: the place to copy. 954f87d0fbbSRusty Russell * @len: the maximum length to copy. 955f87d0fbbSRusty Russell * 956f87d0fbbSRusty Russell * Returns the bytes copied <= len or a negative errno. 957f87d0fbbSRusty Russell */ 958f87d0fbbSRusty Russell ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov, 959f87d0fbbSRusty Russell const void *src, size_t len) 960f87d0fbbSRusty Russell { 961f87d0fbbSRusty Russell return vringh_iov_xfer(wiov, (void *)src, len, xfer_kern); 962f87d0fbbSRusty Russell } 963f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_iov_push_kern); 964f87d0fbbSRusty Russell 965f87d0fbbSRusty Russell /** 966f87d0fbbSRusty Russell * vringh_abandon_kern - we've decided not to handle the descriptor(s). 967f87d0fbbSRusty Russell * @vrh: the vring. 968f87d0fbbSRusty Russell * @num: the number of descriptors to put back (ie. num 969f87d0fbbSRusty Russell * vringh_get_kern() to undo). 970f87d0fbbSRusty Russell * 971f87d0fbbSRusty Russell * The next vringh_get_kern() will return the old descriptor(s) again. 972f87d0fbbSRusty Russell */ 973f87d0fbbSRusty Russell void vringh_abandon_kern(struct vringh *vrh, unsigned int num) 974f87d0fbbSRusty Russell { 975f87d0fbbSRusty Russell /* We only update vring_avail_event(vr) when we want to be notified, 976f87d0fbbSRusty Russell * so we haven't changed that yet. */ 977f87d0fbbSRusty Russell vrh->last_avail_idx -= num; 978f87d0fbbSRusty Russell } 979f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_abandon_kern); 980f87d0fbbSRusty Russell 981f87d0fbbSRusty Russell /** 982f87d0fbbSRusty Russell * vringh_complete_kern - we've finished with descriptor, publish it. 983f87d0fbbSRusty Russell * @vrh: the vring. 984f87d0fbbSRusty Russell * @head: the head as filled in by vringh_getdesc_kern. 985f87d0fbbSRusty Russell * @len: the length of data we have written. 986f87d0fbbSRusty Russell * 987f87d0fbbSRusty Russell * You should check vringh_need_notify_kern() after one or more calls 988f87d0fbbSRusty Russell * to this function. 989f87d0fbbSRusty Russell */ 990f87d0fbbSRusty Russell int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len) 991f87d0fbbSRusty Russell { 992f87d0fbbSRusty Russell struct vring_used_elem used; 993f87d0fbbSRusty Russell 994b9f7ac8cSMichael S. Tsirkin used.id = cpu_to_vringh32(vrh, head); 995b9f7ac8cSMichael S. Tsirkin used.len = cpu_to_vringh32(vrh, len); 996f87d0fbbSRusty Russell 997f87d0fbbSRusty Russell return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern); 998f87d0fbbSRusty Russell } 999f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_complete_kern); 1000f87d0fbbSRusty Russell 1001f87d0fbbSRusty Russell /** 1002f87d0fbbSRusty Russell * vringh_notify_enable_kern - we want to know if something changes. 1003f87d0fbbSRusty Russell * @vrh: the vring. 1004f87d0fbbSRusty Russell * 1005f87d0fbbSRusty Russell * This always enables notifications, but returns false if there are 1006f87d0fbbSRusty Russell * now more buffers available in the vring. 1007f87d0fbbSRusty Russell */ 1008f87d0fbbSRusty Russell bool vringh_notify_enable_kern(struct vringh *vrh) 1009f87d0fbbSRusty Russell { 1010f87d0fbbSRusty Russell return __vringh_notify_enable(vrh, getu16_kern, putu16_kern); 1011f87d0fbbSRusty Russell } 1012f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_enable_kern); 1013f87d0fbbSRusty Russell 1014f87d0fbbSRusty Russell /** 1015f87d0fbbSRusty Russell * vringh_notify_disable_kern - don't tell us if something changes. 1016f87d0fbbSRusty Russell * @vrh: the vring. 1017f87d0fbbSRusty Russell * 1018f87d0fbbSRusty Russell * This is our normal running state: we disable and then only enable when 1019f87d0fbbSRusty Russell * we're going to sleep. 1020f87d0fbbSRusty Russell */ 1021f87d0fbbSRusty Russell void vringh_notify_disable_kern(struct vringh *vrh) 1022f87d0fbbSRusty Russell { 1023f87d0fbbSRusty Russell __vringh_notify_disable(vrh, putu16_kern); 1024f87d0fbbSRusty Russell } 1025f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_notify_disable_kern); 1026f87d0fbbSRusty Russell 1027f87d0fbbSRusty Russell /** 1028f87d0fbbSRusty Russell * vringh_need_notify_kern - must we tell the other side about used buffers? 1029f87d0fbbSRusty Russell * @vrh: the vring we've called vringh_complete_kern() on. 1030f87d0fbbSRusty Russell * 1031f87d0fbbSRusty Russell * Returns -errno or 0 if we don't need to tell the other side, 1 if we do. 1032f87d0fbbSRusty Russell */ 1033f87d0fbbSRusty Russell int vringh_need_notify_kern(struct vringh *vrh) 1034f87d0fbbSRusty Russell { 1035f87d0fbbSRusty Russell return __vringh_need_notify(vrh, getu16_kern); 1036f87d0fbbSRusty Russell } 1037f87d0fbbSRusty Russell EXPORT_SYMBOL(vringh_need_notify_kern); 1038f558a845SDave Jones 1039f558a845SDave Jones MODULE_LICENSE("GPL"); 1040