| /* |
| * Helpers for the host side of a virtio ring. |
| * |
| * Since these may be in userspace, we use (inline) accessors. |
| */ |
| #include <linux/module.h> |
| #include <linux/vringh.h> |
| #include <linux/virtio_ring.h> |
| #include <linux/kernel.h> |
| #include <linux/ratelimit.h> |
| #include <linux/uaccess.h> |
| #include <linux/slab.h> |
| #include <linux/export.h> |
| |
| 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)(u16 *val, const u16 *p), |
| u16 *last_avail_idx) |
| { |
| u16 avail_idx, i, head; |
| int err; |
| |
| err = getu16(&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(&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(int *up_next, u16 *i, void *addr, |
| const struct vring_desc *desc, |
| struct vring_desc **descs, int *desc_max) |
| { |
| /* Indirect tables can't have indirect. */ |
| if (*up_next != -1) { |
| vringh_bad("Multilevel indirect %u->%u", *up_next, *i); |
| return -EINVAL; |
| } |
| |
| if (unlikely(desc->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 & VRING_DESC_F_NEXT) |
| *up_next = desc->next; |
| else |
| *up_next = -2; |
| *descs = addr; |
| *desc_max = desc->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, 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; |
| |
| if (riov) |
| riov->i = riov->used = 0; |
| else if (wiov) |
| wiov->i = wiov->used = 0; |
| else |
| /* You must want something! */ |
| BUG(); |
| |
| 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 & VRING_DESC_F_INDIRECT)) { |
| /* Make sure it's OK, and get offset. */ |
| len = desc.len; |
| if (!rcheck(vrh, desc.addr, &len, &range, getrange)) { |
| err = -EINVAL; |
| goto fail; |
| } |
| |
| if (unlikely(len != desc.len)) { |
| slow = true; |
| /* We need to save this range to use offset */ |
| slowrange = range; |
| } |
| |
| addr = (void *)(long)(desc.addr + range.offset); |
| err = move_to_indirect(&up_next, &i, addr, &desc, |
| &descs, &desc_max); |
| if (err) |
| goto fail; |
| continue; |
| } |
| |
| if (count++ == vrh->vring.num) { |
| vringh_bad("Descriptor loop in %p", descs); |
| err = -ELOOP; |
| goto fail; |
| } |
| |
| if (desc.flags & VRING_DESC_F_WRITE) |
| iov = wiov; |
| else { |
| iov = riov; |
| if (unlikely(wiov && wiov->i)) { |
| 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 = desc.len; |
| if (!rcheck(vrh, desc.addr, &len, &range, getrange)) { |
| err = -EINVAL; |
| goto fail; |
| } |
| addr = (void *)(unsigned long)(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 != desc.len)) { |
| desc.len -= len; |
| desc.addr += len; |
| goto again; |
| } |
| |
| if (desc.flags & VRING_DESC_F_NEXT) { |
| i = 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; |
| } 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)(u16 *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->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)(u16 *val, const u16 *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(&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(&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)(u16 *val, const u16 *p), |
| int (*putu16)(u16 *p, u16 val)) |
| { |
| u16 avail; |
| |
| if (!vrh->event_indices) { |
| /* Old-school; update flags. */ |
| if (putu16(&vrh->vring.used->flags, 0) != 0) { |
| vringh_bad("Clearing used flags %p", |
| &vrh->vring.used->flags); |
| return true; |
| } |
| } else { |
| if (putu16(&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(&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)(u16 *p, u16 val)) |
| { |
| if (!vrh->event_indices) { |
| /* Old-school; update flags. */ |
| if (putu16(&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(u16 *val, const u16 *p) |
| { |
| return get_user(*val, (__force u16 __user *)p); |
| } |
| |
| static inline int putu16_user(u16 *p, u16 val) |
| { |
| return put_user(val, (__force u16 __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, u32 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->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 = head; |
| used.len = 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(u16 *val, const u16 *p) |
| { |
| *val = ACCESS_ONCE(*p); |
| return 0; |
| } |
| |
| static inline int putu16_kern(u16 *p, u16 val) |
| { |
| ACCESS_ONCE(*p) = 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, u32 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->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 = head; |
| used.len = 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"); |