/* * Helpers for the host side of a virtio ring. * * Since these may be in userspace, we use (inline) accessors. */ #include #include #include #include #include #include #include #include #include static __printf(1,2) __cold void vringh_bad(const char *fmt, ...) { static DEFINE_RATELIMIT_STATE(vringh_rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); if (__ratelimit(&vringh_rs)) { va_list ap; va_start(ap, fmt); printk(KERN_NOTICE "vringh:"); vprintk(fmt, ap); va_end(ap); } } /* Returns vring->num if empty, -ve on error. */ static inline int __vringh_get_head(const struct vringh *vrh, int (*getu16)(const struct vringh *vrh, u16 *val, const __virtio16 *p), u16 *last_avail_idx) { u16 avail_idx, i, head; int err; err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx); if (err) { vringh_bad("Failed to access avail idx at %p", &vrh->vring.avail->idx); return err; } if (*last_avail_idx == avail_idx) return vrh->vring.num; /* Only get avail ring entries after they have been exposed by guest. */ virtio_rmb(vrh->weak_barriers); i = *last_avail_idx & (vrh->vring.num - 1); err = getu16(vrh, &head, &vrh->vring.avail->ring[i]); if (err) { vringh_bad("Failed to read head: idx %d address %p", *last_avail_idx, &vrh->vring.avail->ring[i]); return err; } if (head >= vrh->vring.num) { vringh_bad("Guest says index %u > %u is available", head, vrh->vring.num); return -EINVAL; } (*last_avail_idx)++; return head; } /* Copy some bytes to/from the iovec. Returns num copied. */ static inline ssize_t vringh_iov_xfer(struct vringh_kiov *iov, void *ptr, size_t len, int (*xfer)(void *addr, void *ptr, size_t len)) { int err, done = 0; while (len && iov->i < iov->used) { size_t partlen; partlen = min(iov->iov[iov->i].iov_len, len); err = xfer(iov->iov[iov->i].iov_base, ptr, partlen); if (err) return err; done += partlen; len -= partlen; ptr += partlen; iov->consumed += partlen; iov->iov[iov->i].iov_len -= partlen; iov->iov[iov->i].iov_base += partlen; if (!iov->iov[iov->i].iov_len) { /* Fix up old iov element then increment. */ iov->iov[iov->i].iov_len = iov->consumed; iov->iov[iov->i].iov_base -= iov->consumed; iov->consumed = 0; iov->i++; } } return done; } /* May reduce *len if range is shorter. */ static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len, struct vringh_range *range, bool (*getrange)(struct vringh *, u64, struct vringh_range *)) { if (addr < range->start || addr > range->end_incl) { if (!getrange(vrh, addr, range)) return false; } BUG_ON(addr < range->start || addr > range->end_incl); /* To end of memory? */ if (unlikely(addr + *len == 0)) { if (range->end_incl == -1ULL) return true; goto truncate; } /* Otherwise, don't wrap. */ if (addr + *len < addr) { vringh_bad("Wrapping descriptor %zu@0x%llx", *len, (unsigned long long)addr); return false; } if (unlikely(addr + *len - 1 > range->end_incl)) goto truncate; return true; truncate: *len = range->end_incl + 1 - addr; return true; } static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len, struct vringh_range *range, bool (*getrange)(struct vringh *, u64, struct vringh_range *)) { return true; } /* No reason for this code to be inline. */ static int move_to_indirect(const struct vringh *vrh, int *up_next, u16 *i, void *addr, const struct vring_desc *desc, struct vring_desc **descs, int *desc_max) { u32 len; /* Indirect tables can't have indirect. */ if (*up_next != -1) { vringh_bad("Multilevel indirect %u->%u", *up_next, *i); return -EINVAL; } len = vringh32_to_cpu(vrh, desc->len); if (unlikely(len % sizeof(struct vring_desc))) { vringh_bad("Strange indirect len %u", desc->len); return -EINVAL; } /* We will check this when we follow it! */ if (desc->flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) *up_next = vringh16_to_cpu(vrh, desc->next); else *up_next = -2; *descs = addr; *desc_max = len / sizeof(struct vring_desc); /* Now, start at the first indirect. */ *i = 0; return 0; } static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp) { struct kvec *new; unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2; if (new_num < 8) new_num = 8; flag = (iov->max_num & VRINGH_IOV_ALLOCATED); if (flag) new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp); else { new = kmalloc(new_num * sizeof(struct iovec), gfp); if (new) { memcpy(new, iov->iov, iov->max_num * sizeof(struct iovec)); flag = VRINGH_IOV_ALLOCATED; } } if (!new) return -ENOMEM; iov->iov = new; iov->max_num = (new_num | flag); return 0; } static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next, struct vring_desc **descs, int *desc_max) { u16 i = *up_next; *up_next = -1; *descs = vrh->vring.desc; *desc_max = vrh->vring.num; return i; } static int slow_copy(struct vringh *vrh, void *dst, const void *src, bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len, struct vringh_range *range, bool (*getrange)(struct vringh *vrh, u64, struct vringh_range *)), bool (*getrange)(struct vringh *vrh, u64 addr, struct vringh_range *r), struct vringh_range *range, int (*copy)(void *dst, const void *src, size_t len)) { size_t part, len = sizeof(struct vring_desc); do { u64 addr; int err; part = len; addr = (u64)(unsigned long)src - range->offset; if (!rcheck(vrh, addr, &part, range, getrange)) return -EINVAL; err = copy(dst, src, part); if (err) return err; dst += part; src += part; len -= part; } while (len); return 0; } static inline int __vringh_iov(struct vringh *vrh, u16 i, struct vringh_kiov *riov, struct vringh_kiov *wiov, bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len, struct vringh_range *range, bool (*getrange)(struct vringh *, u64, struct vringh_range *)), bool (*getrange)(struct vringh *, u64, struct vringh_range *), gfp_t gfp, int (*copy)(void *dst, const void *src, size_t len)) { int err, count = 0, indirect_count = 0, up_next, desc_max; struct vring_desc desc, *descs; struct vringh_range range = { -1ULL, 0 }, slowrange; bool slow = false; /* We start traversing vring's descriptor table. */ descs = vrh->vring.desc; desc_max = vrh->vring.num; up_next = -1; /* You must want something! */ if (WARN_ON(!riov && !wiov)) return -EINVAL; if (riov) riov->i = riov->used = 0; if (wiov) wiov->i = wiov->used = 0; for (;;) { void *addr; struct vringh_kiov *iov; size_t len; if (unlikely(slow)) err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange, &slowrange, copy); else err = copy(&desc, &descs[i], sizeof(desc)); if (unlikely(err)) goto fail; if (unlikely(desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_INDIRECT))) { u64 a = vringh64_to_cpu(vrh, desc.addr); /* Make sure it's OK, and get offset. */ len = vringh32_to_cpu(vrh, desc.len); if (!rcheck(vrh, a, &len, &range, getrange)) { err = -EINVAL; goto fail; } if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) { slow = true; /* We need to save this range to use offset */ slowrange = range; } addr = (void *)(long)(a + range.offset); err = move_to_indirect(vrh, &up_next, &i, addr, &desc, &descs, &desc_max); if (err) goto fail; continue; } if (up_next == -1) count++; else indirect_count++; if (count > vrh->vring.num || indirect_count > desc_max) { vringh_bad("Descriptor loop in %p", descs); err = -ELOOP; goto fail; } if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_WRITE)) iov = wiov; else { iov = riov; if (unlikely(wiov && wiov->used)) { vringh_bad("Readable desc %p after writable", &descs[i]); err = -EINVAL; goto fail; } } if (!iov) { vringh_bad("Unexpected %s desc", !wiov ? "writable" : "readable"); err = -EPROTO; goto fail; } again: /* Make sure it's OK, and get offset. */ len = vringh32_to_cpu(vrh, desc.len); if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range, getrange)) { err = -EINVAL; goto fail; } addr = (void *)(unsigned long)(vringh64_to_cpu(vrh, desc.addr) + range.offset); if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) { err = resize_iovec(iov, gfp); if (err) goto fail; } iov->iov[iov->used].iov_base = addr; iov->iov[iov->used].iov_len = len; iov->used++; if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) { desc.len = cpu_to_vringh32(vrh, vringh32_to_cpu(vrh, desc.len) - len); desc.addr = cpu_to_vringh64(vrh, vringh64_to_cpu(vrh, desc.addr) + len); goto again; } if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) { i = vringh16_to_cpu(vrh, desc.next); } else { /* Just in case we need to finish traversing above. */ if (unlikely(up_next > 0)) { i = return_from_indirect(vrh, &up_next, &descs, &desc_max); slow = false; indirect_count = 0; } else break; } if (i >= desc_max) { vringh_bad("Chained index %u > %u", i, desc_max); err = -EINVAL; goto fail; } } return 0; fail: return err; } static inline int __vringh_complete(struct vringh *vrh, const struct vring_used_elem *used, unsigned int num_used, int (*putu16)(const struct vringh *vrh, __virtio16 *p, u16 val), int (*putused)(struct vring_used_elem *dst, const struct vring_used_elem *src, unsigned num)) { struct vring_used *used_ring; int err; u16 used_idx, off; used_ring = vrh->vring.used; used_idx = vrh->last_used_idx + vrh->completed; off = used_idx % vrh->vring.num; /* Compiler knows num_used == 1 sometimes, hence extra check */ if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) { u16 part = vrh->vring.num - off; err = putused(&used_ring->ring[off], used, part); if (!err) err = putused(&used_ring->ring[0], used + part, num_used - part); } else err = putused(&used_ring->ring[off], used, num_used); if (err) { vringh_bad("Failed to write %u used entries %u at %p", num_used, off, &used_ring->ring[off]); return err; } /* Make sure buffer is written before we update index. */ virtio_wmb(vrh->weak_barriers); err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used); if (err) { vringh_bad("Failed to update used index at %p", &vrh->vring.used->idx); return err; } vrh->completed += num_used; return 0; } static inline int __vringh_need_notify(struct vringh *vrh, int (*getu16)(const struct vringh *vrh, u16 *val, const __virtio16 *p)) { bool notify; u16 used_event; int err; /* Flush out used index update. This is paired with the * barrier that the Guest executes when enabling * interrupts. */ virtio_mb(vrh->weak_barriers); /* Old-style, without event indices. */ if (!vrh->event_indices) { u16 flags; err = getu16(vrh, &flags, &vrh->vring.avail->flags); if (err) { vringh_bad("Failed to get flags at %p", &vrh->vring.avail->flags); return err; } return (!(flags & VRING_AVAIL_F_NO_INTERRUPT)); } /* Modern: we know when other side wants to know. */ err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring)); if (err) { vringh_bad("Failed to get used event idx at %p", &vring_used_event(&vrh->vring)); return err; } /* Just in case we added so many that we wrap. */ if (unlikely(vrh->completed > 0xffff)) notify = true; else notify = vring_need_event(used_event, vrh->last_used_idx + vrh->completed, vrh->last_used_idx); vrh->last_used_idx += vrh->completed; vrh->completed = 0; return notify; } static inline bool __vringh_notify_enable(struct vringh *vrh, int (*getu16)(const struct vringh *vrh, u16 *val, const __virtio16 *p), int (*putu16)(const struct vringh *vrh, __virtio16 *p, u16 val)) { u16 avail; if (!vrh->event_indices) { /* Old-school; update flags. */ if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) { vringh_bad("Clearing used flags %p", &vrh->vring.used->flags); return true; } } else { if (putu16(vrh, &vring_avail_event(&vrh->vring), vrh->last_avail_idx) != 0) { vringh_bad("Updating avail event index %p", &vring_avail_event(&vrh->vring)); return true; } } /* They could have slipped one in as we were doing that: make * sure it's written, then check again. */ virtio_mb(vrh->weak_barriers); if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) { vringh_bad("Failed to check avail idx at %p", &vrh->vring.avail->idx); return true; } /* This is unlikely, so we just leave notifications enabled * (if we're using event_indices, we'll only get one * notification anyway). */ return avail == vrh->last_avail_idx; } static inline void __vringh_notify_disable(struct vringh *vrh, int (*putu16)(const struct vringh *vrh, __virtio16 *p, u16 val)) { if (!vrh->event_indices) { /* Old-school; update flags. */ if (putu16(vrh, &vrh->vring.used->flags, VRING_USED_F_NO_NOTIFY)) { vringh_bad("Setting used flags %p", &vrh->vring.used->flags); } } } /* Userspace access helpers: in this case, addresses are really userspace. */ static inline int getu16_user(const struct vringh *vrh, u16 *val, const __virtio16 *p) { __virtio16 v = 0; int rc = get_user(v, (__force __virtio16 __user *)p); *val = vringh16_to_cpu(vrh, v); return rc; } static inline int putu16_user(const struct vringh *vrh, __virtio16 *p, u16 val) { __virtio16 v = cpu_to_vringh16(vrh, val); return put_user(v, (__force __virtio16 __user *)p); } static inline int copydesc_user(void *dst, const void *src, size_t len) { return copy_from_user(dst, (__force void __user *)src, len) ? -EFAULT : 0; } static inline int putused_user(struct vring_used_elem *dst, const struct vring_used_elem *src, unsigned int num) { return copy_to_user((__force void __user *)dst, src, sizeof(*dst) * num) ? -EFAULT : 0; } static inline int xfer_from_user(void *src, void *dst, size_t len) { return copy_from_user(dst, (__force void __user *)src, len) ? -EFAULT : 0; } static inline int xfer_to_user(void *dst, void *src, size_t len) { return copy_to_user((__force void __user *)dst, src, len) ? -EFAULT : 0; } /** * vringh_init_user - initialize a vringh for a userspace vring. * @vrh: the vringh to initialize. * @features: the feature bits for this ring. * @num: the number of elements. * @weak_barriers: true if we only need memory barriers, not I/O. * @desc: the userpace descriptor pointer. * @avail: the userpace avail pointer. * @used: the userpace used pointer. * * Returns an error if num is invalid: you should check pointers * yourself! */ int vringh_init_user(struct vringh *vrh, u64 features, unsigned int num, bool weak_barriers, struct vring_desc __user *desc, struct vring_avail __user *avail, struct vring_used __user *used) { /* Sane power of 2 please! */ if (!num || num > 0xffff || (num & (num - 1))) { vringh_bad("Bad ring size %u", num); return -EINVAL; } vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1)); vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX)); vrh->weak_barriers = weak_barriers; vrh->completed = 0; vrh->last_avail_idx = 0; vrh->last_used_idx = 0; vrh->vring.num = num; /* vring expects kernel addresses, but only used via accessors. */ vrh->vring.desc = (__force struct vring_desc *)desc; vrh->vring.avail = (__force struct vring_avail *)avail; vrh->vring.used = (__force struct vring_used *)used; return 0; } EXPORT_SYMBOL(vringh_init_user); /** * vringh_getdesc_user - get next available descriptor from userspace ring. * @vrh: the userspace vring. * @riov: where to put the readable descriptors (or NULL) * @wiov: where to put the writable descriptors (or NULL) * @getrange: function to call to check ranges. * @head: head index we received, for passing to vringh_complete_user(). * * Returns 0 if there was no descriptor, 1 if there was, or -errno. * * Note that on error return, you can tell the difference between an * invalid ring and a single invalid descriptor: in the former case, * *head will be vrh->vring.num. You may be able to ignore an invalid * descriptor, but there's not much you can do with an invalid ring. * * Note that you may need to clean up riov and wiov, even on error! */ int vringh_getdesc_user(struct vringh *vrh, struct vringh_iov *riov, struct vringh_iov *wiov, bool (*getrange)(struct vringh *vrh, u64 addr, struct vringh_range *r), u16 *head) { int err; *head = vrh->vring.num; err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx); if (err < 0) return err; /* Empty... */ if (err == vrh->vring.num) return 0; /* We need the layouts to be the identical for this to work */ BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov)); BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) != offsetof(struct vringh_iov, iov)); BUILD_BUG_ON(offsetof(struct vringh_kiov, i) != offsetof(struct vringh_iov, i)); BUILD_BUG_ON(offsetof(struct vringh_kiov, used) != offsetof(struct vringh_iov, used)); BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) != offsetof(struct vringh_iov, max_num)); BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); BUILD_BUG_ON(offsetof(struct iovec, iov_base) != offsetof(struct kvec, iov_base)); BUILD_BUG_ON(offsetof(struct iovec, iov_len) != offsetof(struct kvec, iov_len)); BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base) != sizeof(((struct kvec *)NULL)->iov_base)); BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len) != sizeof(((struct kvec *)NULL)->iov_len)); *head = err; err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov, (struct vringh_kiov *)wiov, range_check, getrange, GFP_KERNEL, copydesc_user); if (err) return err; return 1; } EXPORT_SYMBOL(vringh_getdesc_user); /** * vringh_iov_pull_user - copy bytes from vring_iov. * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume) * @dst: the place to copy. * @len: the maximum length to copy. * * Returns the bytes copied <= len or a negative errno. */ ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len) { return vringh_iov_xfer((struct vringh_kiov *)riov, dst, len, xfer_from_user); } EXPORT_SYMBOL(vringh_iov_pull_user); /** * vringh_iov_push_user - copy bytes into vring_iov. * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume) * @dst: the place to copy. * @len: the maximum length to copy. * * Returns the bytes copied <= len or a negative errno. */ ssize_t vringh_iov_push_user(struct vringh_iov *wiov, const void *src, size_t len) { return vringh_iov_xfer((struct vringh_kiov *)wiov, (void *)src, len, xfer_to_user); } EXPORT_SYMBOL(vringh_iov_push_user); /** * vringh_abandon_user - we've decided not to handle the descriptor(s). * @vrh: the vring. * @num: the number of descriptors to put back (ie. num * vringh_get_user() to undo). * * The next vringh_get_user() will return the old descriptor(s) again. */ void vringh_abandon_user(struct vringh *vrh, unsigned int num) { /* We only update vring_avail_event(vr) when we want to be notified, * so we haven't changed that yet. */ vrh->last_avail_idx -= num; } EXPORT_SYMBOL(vringh_abandon_user); /** * vringh_complete_user - we've finished with descriptor, publish it. * @vrh: the vring. * @head: the head as filled in by vringh_getdesc_user. * @len: the length of data we have written. * * You should check vringh_need_notify_user() after one or more calls * to this function. */ int vringh_complete_user(struct vringh *vrh, u16 head, u32 len) { struct vring_used_elem used; used.id = cpu_to_vringh32(vrh, head); used.len = cpu_to_vringh32(vrh, len); return __vringh_complete(vrh, &used, 1, putu16_user, putused_user); } EXPORT_SYMBOL(vringh_complete_user); /** * vringh_complete_multi_user - we've finished with many descriptors. * @vrh: the vring. * @used: the head, length pairs. * @num_used: the number of used elements. * * You should check vringh_need_notify_user() after one or more calls * to this function. */ int vringh_complete_multi_user(struct vringh *vrh, const struct vring_used_elem used[], unsigned num_used) { return __vringh_complete(vrh, used, num_used, putu16_user, putused_user); } EXPORT_SYMBOL(vringh_complete_multi_user); /** * vringh_notify_enable_user - we want to know if something changes. * @vrh: the vring. * * This always enables notifications, but returns false if there are * now more buffers available in the vring. */ bool vringh_notify_enable_user(struct vringh *vrh) { return __vringh_notify_enable(vrh, getu16_user, putu16_user); } EXPORT_SYMBOL(vringh_notify_enable_user); /** * vringh_notify_disable_user - don't tell us if something changes. * @vrh: the vring. * * This is our normal running state: we disable and then only enable when * we're going to sleep. */ void vringh_notify_disable_user(struct vringh *vrh) { __vringh_notify_disable(vrh, putu16_user); } EXPORT_SYMBOL(vringh_notify_disable_user); /** * vringh_need_notify_user - must we tell the other side about used buffers? * @vrh: the vring we've called vringh_complete_user() on. * * Returns -errno or 0 if we don't need to tell the other side, 1 if we do. */ int vringh_need_notify_user(struct vringh *vrh) { return __vringh_need_notify(vrh, getu16_user); } EXPORT_SYMBOL(vringh_need_notify_user); /* Kernelspace access helpers. */ static inline int getu16_kern(const struct vringh *vrh, u16 *val, const __virtio16 *p) { *val = vringh16_to_cpu(vrh, ACCESS_ONCE(*p)); return 0; } static inline int putu16_kern(const struct vringh *vrh, __virtio16 *p, u16 val) { ACCESS_ONCE(*p) = cpu_to_vringh16(vrh, val); return 0; } static inline int copydesc_kern(void *dst, const void *src, size_t len) { memcpy(dst, src, len); return 0; } static inline int putused_kern(struct vring_used_elem *dst, const struct vring_used_elem *src, unsigned int num) { memcpy(dst, src, num * sizeof(*dst)); return 0; } static inline int xfer_kern(void *src, void *dst, size_t len) { memcpy(dst, src, len); return 0; } /** * vringh_init_kern - initialize a vringh for a kernelspace vring. * @vrh: the vringh to initialize. * @features: the feature bits for this ring. * @num: the number of elements. * @weak_barriers: true if we only need memory barriers, not I/O. * @desc: the userpace descriptor pointer. * @avail: the userpace avail pointer. * @used: the userpace used pointer. * * Returns an error if num is invalid. */ int vringh_init_kern(struct vringh *vrh, u64 features, unsigned int num, bool weak_barriers, struct vring_desc *desc, struct vring_avail *avail, struct vring_used *used) { /* Sane power of 2 please! */ if (!num || num > 0xffff || (num & (num - 1))) { vringh_bad("Bad ring size %u", num); return -EINVAL; } vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1)); vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX)); vrh->weak_barriers = weak_barriers; vrh->completed = 0; vrh->last_avail_idx = 0; vrh->last_used_idx = 0; vrh->vring.num = num; vrh->vring.desc = desc; vrh->vring.avail = avail; vrh->vring.used = used; return 0; } EXPORT_SYMBOL(vringh_init_kern); /** * vringh_getdesc_kern - get next available descriptor from kernelspace ring. * @vrh: the kernelspace vring. * @riov: where to put the readable descriptors (or NULL) * @wiov: where to put the writable descriptors (or NULL) * @head: head index we received, for passing to vringh_complete_kern(). * @gfp: flags for allocating larger riov/wiov. * * Returns 0 if there was no descriptor, 1 if there was, or -errno. * * Note that on error return, you can tell the difference between an * invalid ring and a single invalid descriptor: in the former case, * *head will be vrh->vring.num. You may be able to ignore an invalid * descriptor, but there's not much you can do with an invalid ring. * * Note that you may need to clean up riov and wiov, even on error! */ int vringh_getdesc_kern(struct vringh *vrh, struct vringh_kiov *riov, struct vringh_kiov *wiov, u16 *head, gfp_t gfp) { int err; err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx); if (err < 0) return err; /* Empty... */ if (err == vrh->vring.num) return 0; *head = err; err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL, gfp, copydesc_kern); if (err) return err; return 1; } EXPORT_SYMBOL(vringh_getdesc_kern); /** * vringh_iov_pull_kern - copy bytes from vring_iov. * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume) * @dst: the place to copy. * @len: the maximum length to copy. * * Returns the bytes copied <= len or a negative errno. */ ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len) { return vringh_iov_xfer(riov, dst, len, xfer_kern); } EXPORT_SYMBOL(vringh_iov_pull_kern); /** * vringh_iov_push_kern - copy bytes into vring_iov. * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume) * @dst: the place to copy. * @len: the maximum length to copy. * * Returns the bytes copied <= len or a negative errno. */ ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov, const void *src, size_t len) { return vringh_iov_xfer(wiov, (void *)src, len, xfer_kern); } EXPORT_SYMBOL(vringh_iov_push_kern); /** * vringh_abandon_kern - we've decided not to handle the descriptor(s). * @vrh: the vring. * @num: the number of descriptors to put back (ie. num * vringh_get_kern() to undo). * * The next vringh_get_kern() will return the old descriptor(s) again. */ void vringh_abandon_kern(struct vringh *vrh, unsigned int num) { /* We only update vring_avail_event(vr) when we want to be notified, * so we haven't changed that yet. */ vrh->last_avail_idx -= num; } EXPORT_SYMBOL(vringh_abandon_kern); /** * vringh_complete_kern - we've finished with descriptor, publish it. * @vrh: the vring. * @head: the head as filled in by vringh_getdesc_kern. * @len: the length of data we have written. * * You should check vringh_need_notify_kern() after one or more calls * to this function. */ int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len) { struct vring_used_elem used; used.id = cpu_to_vringh32(vrh, head); used.len = cpu_to_vringh32(vrh, len); return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern); } EXPORT_SYMBOL(vringh_complete_kern); /** * vringh_notify_enable_kern - we want to know if something changes. * @vrh: the vring. * * This always enables notifications, but returns false if there are * now more buffers available in the vring. */ bool vringh_notify_enable_kern(struct vringh *vrh) { return __vringh_notify_enable(vrh, getu16_kern, putu16_kern); } EXPORT_SYMBOL(vringh_notify_enable_kern); /** * vringh_notify_disable_kern - don't tell us if something changes. * @vrh: the vring. * * This is our normal running state: we disable and then only enable when * we're going to sleep. */ void vringh_notify_disable_kern(struct vringh *vrh) { __vringh_notify_disable(vrh, putu16_kern); } EXPORT_SYMBOL(vringh_notify_disable_kern); /** * vringh_need_notify_kern - must we tell the other side about used buffers? * @vrh: the vring we've called vringh_complete_kern() on. * * Returns -errno or 0 if we don't need to tell the other side, 1 if we do. */ int vringh_need_notify_kern(struct vringh *vrh) { return __vringh_need_notify(vrh, getu16_kern); } EXPORT_SYMBOL(vringh_need_notify_kern); MODULE_LICENSE("GPL");