diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 220 |
1 files changed, 157 insertions, 63 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 245177c..a78ad45 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -98,16 +98,36 @@ struct vring_virtqueue #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) +static inline struct scatterlist *sg_next_chained(struct scatterlist *sg, + unsigned int *count) +{ + return sg_next(sg); +} + +static inline struct scatterlist *sg_next_arr(struct scatterlist *sg, + unsigned int *count) +{ + if (--(*count) == 0) + return NULL; + return sg + 1; +} + /* Set up an indirect table of descriptors and add it to the queue. */ -static int vring_add_indirect(struct vring_virtqueue *vq, - struct scatterlist sg[], - unsigned int out, - unsigned int in, - gfp_t gfp) +static inline int vring_add_indirect(struct vring_virtqueue *vq, + struct scatterlist *sgs[], + struct scatterlist *(*next) + (struct scatterlist *, unsigned int *), + unsigned int total_sg, + unsigned int total_out, + unsigned int total_in, + unsigned int out_sgs, + unsigned int in_sgs, + gfp_t gfp) { struct vring_desc *desc; unsigned head; - int i; + struct scatterlist *sg; + int i, n; /* * We require lowmem mappings for the descriptors because @@ -116,25 +136,31 @@ static int vring_add_indirect(struct vring_virtqueue *vq, */ gfp &= ~(__GFP_HIGHMEM | __GFP_HIGH); - desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); + desc = kmalloc(total_sg * sizeof(struct vring_desc), gfp); if (!desc) return -ENOMEM; - /* Transfer entries from the sg list into the indirect page */ - for (i = 0; i < out; i++) { - desc[i].flags = VRING_DESC_F_NEXT; - desc[i].addr = sg_phys(sg); - desc[i].len = sg->length; - desc[i].next = i+1; - sg++; + /* Transfer entries from the sg lists into the indirect page */ + i = 0; + for (n = 0; n < out_sgs; n++) { + for (sg = sgs[n]; sg; sg = next(sg, &total_out)) { + desc[i].flags = VRING_DESC_F_NEXT; + desc[i].addr = sg_phys(sg); + desc[i].len = sg->length; + desc[i].next = i+1; + i++; + } } - for (; i < (out + in); i++) { - desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; - desc[i].addr = sg_phys(sg); - desc[i].len = sg->length; - desc[i].next = i+1; - sg++; + for (; n < (out_sgs + in_sgs); n++) { + for (sg = sgs[n]; sg; sg = next(sg, &total_in)) { + desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; + desc[i].addr = sg_phys(sg); + desc[i].len = sg->length; + desc[i].next = i+1; + i++; + } } + BUG_ON(i != total_sg); /* Last one doesn't continue. */ desc[i-1].flags &= ~VRING_DESC_F_NEXT; @@ -155,29 +181,20 @@ static int vring_add_indirect(struct vring_virtqueue *vq, return head; } -/** - * virtqueue_add_buf - expose buffer to other end - * @vq: the struct virtqueue we're talking about. - * @sg: the description of the buffer(s). - * @out_num: the number of sg readable by other side - * @in_num: the number of sg which are writable (after readable ones) - * @data: the token identifying the buffer. - * @gfp: how to do memory allocations (if necessary). - * - * Caller must ensure we don't call this with other virtqueue operations - * at the same time (except where noted). - * - * Returns zero or a negative error (ie. ENOSPC, ENOMEM). - */ -int virtqueue_add_buf(struct virtqueue *_vq, - struct scatterlist sg[], - unsigned int out, - unsigned int in, - void *data, - gfp_t gfp) +static inline int virtqueue_add(struct virtqueue *_vq, + struct scatterlist *sgs[], + struct scatterlist *(*next) + (struct scatterlist *, unsigned int *), + unsigned int total_out, + unsigned int total_in, + unsigned int out_sgs, + unsigned int in_sgs, + void *data, + gfp_t gfp) { struct vring_virtqueue *vq = to_vvq(_vq); - unsigned int i, avail, uninitialized_var(prev); + struct scatterlist *sg; + unsigned int i, n, avail, uninitialized_var(prev), total_sg; int head; START_USE(vq); @@ -197,46 +214,54 @@ int virtqueue_add_buf(struct virtqueue *_vq, } #endif + total_sg = total_in + total_out; + /* If the host supports indirect descriptor tables, and we have multiple * buffers, then go indirect. FIXME: tune this threshold */ - if (vq->indirect && (out + in) > 1 && vq->vq.num_free) { - head = vring_add_indirect(vq, sg, out, in, gfp); + if (vq->indirect && total_sg > 1 && vq->vq.num_free) { + head = vring_add_indirect(vq, sgs, next, total_sg, total_out, + total_in, + out_sgs, in_sgs, gfp); if (likely(head >= 0)) goto add_head; } - BUG_ON(out + in > vq->vring.num); - BUG_ON(out + in == 0); + BUG_ON(total_sg > vq->vring.num); + BUG_ON(total_sg == 0); - if (vq->vq.num_free < out + in) { + if (vq->vq.num_free < total_sg) { pr_debug("Can't add buf len %i - avail = %i\n", - out + in, vq->vq.num_free); + total_sg, vq->vq.num_free); /* FIXME: for historical reasons, we force a notify here if * there are outgoing parts to the buffer. Presumably the * host should service the ring ASAP. */ - if (out) + if (out_sgs) vq->notify(&vq->vq); END_USE(vq); return -ENOSPC; } /* We're about to use some buffers from the free list. */ - vq->vq.num_free -= out + in; - - head = vq->free_head; - for (i = vq->free_head; out; i = vq->vring.desc[i].next, out--) { - vq->vring.desc[i].flags = VRING_DESC_F_NEXT; - vq->vring.desc[i].addr = sg_phys(sg); - vq->vring.desc[i].len = sg->length; - prev = i; - sg++; + vq->vq.num_free -= total_sg; + + head = i = vq->free_head; + for (n = 0; n < out_sgs; n++) { + for (sg = sgs[n]; sg; sg = next(sg, &total_out)) { + vq->vring.desc[i].flags = VRING_DESC_F_NEXT; + vq->vring.desc[i].addr = sg_phys(sg); + vq->vring.desc[i].len = sg->length; + prev = i; + i = vq->vring.desc[i].next; + } } - for (; in; i = vq->vring.desc[i].next, in--) { - vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; - vq->vring.desc[i].addr = sg_phys(sg); - vq->vring.desc[i].len = sg->length; - prev = i; - sg++; + for (; n < (out_sgs + in_sgs); n++) { + for (sg = sgs[n]; sg; sg = next(sg, &total_in)) { + vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; + vq->vring.desc[i].addr = sg_phys(sg); + vq->vring.desc[i].len = sg->length; + prev = i; + i = vq->vring.desc[i].next; + } } /* Last one doesn't continue. */ vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT; @@ -269,9 +294,78 @@ add_head: return 0; } + +/** + * virtqueue_add_buf - expose buffer to other end + * @vq: the struct virtqueue we're talking about. + * @sg: the description of the buffer(s). + * @out_num: the number of sg readable by other side + * @in_num: the number of sg which are writable (after readable ones) + * @data: the token identifying the buffer. + * @gfp: how to do memory allocations (if necessary). + * + * Caller must ensure we don't call this with other virtqueue operations + * at the same time (except where noted). + * + * Returns zero or a negative error (ie. ENOSPC, ENOMEM). + */ +int virtqueue_add_buf(struct virtqueue *_vq, + struct scatterlist sg[], + unsigned int out, + unsigned int in, + void *data, + gfp_t gfp) +{ + struct scatterlist *sgs[2]; + + sgs[0] = sg; + sgs[1] = sg + out; + + return virtqueue_add(_vq, sgs, sg_next_arr, + out, in, out ? 1 : 0, in ? 1 : 0, data, gfp); +} EXPORT_SYMBOL_GPL(virtqueue_add_buf); /** + * virtqueue_add_sgs - expose buffers to other end + * @vq: the struct virtqueue we're talking about. + * @sgs: array of terminated scatterlists. + * @out_num: the number of scatterlists readable by other side + * @in_num: the number of scatterlists which are writable (after readable ones) + * @data: the token identifying the buffer. + * @gfp: how to do memory allocations (if necessary). + * + * Caller must ensure we don't call this with other virtqueue operations + * at the same time (except where noted). + * + * Returns zero or a negative error (ie. ENOSPC, ENOMEM). + */ +int virtqueue_add_sgs(struct virtqueue *_vq, + struct scatterlist *sgs[], + unsigned int out_sgs, + unsigned int in_sgs, + void *data, + gfp_t gfp) +{ + unsigned int i, total_out, total_in; + + /* Count them first. */ + for (i = total_out = total_in = 0; i < out_sgs; i++) { + struct scatterlist *sg; + for (sg = sgs[i]; sg; sg = sg_next(sg)) + total_out++; + } + for (; i < out_sgs + in_sgs; i++) { + struct scatterlist *sg; + for (sg = sgs[i]; sg; sg = sg_next(sg)) + total_in++; + } + return virtqueue_add(_vq, sgs, sg_next_chained, + total_out, total_in, out_sgs, in_sgs, data, gfp); +} +EXPORT_SYMBOL_GPL(virtqueue_add_sgs); + +/** * virtqueue_kick_prepare - first half of split virtqueue_kick call. * @vq: the struct virtqueue * |
