On Thu, Mar 2, 2023 at 7:59 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> DMA-related logic is separated from the virtqueue_add_vring_split() to
> prepare for subsequent support for premapped.
>
> DMA address will be saved as sg->dma_address, then
> virtqueue_add_vring_split() will use it directly.
>
> If it is a premapped scene, the transmitted sgs should have saved DMA
> address in dma_address, and in virtio core, we need to pass
> virtqueue_map_sgs().
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_ring.c | 116 ++++++++++++++++++++++++-----------
> 1 file changed, 80 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 3005893ecc61..17520f0d7649 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -520,6 +520,73 @@ static inline unsigned int virtqueue_add_desc_split(struct virtqueue *vq,
> return next;
> }
>
> +static int virtqueue_map_sgs(struct vring_virtqueue *vq,
> + struct scatterlist *sgs[],
> + unsigned int total_sg,
> + unsigned int out_sgs,
> + unsigned int in_sgs)
> +{
> + struct scatterlist *sg;
> + unsigned int n;
> +
> + for (n = 0; n < out_sgs; n++) {
> + for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> + dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
> +
> + if (vring_mapping_error(vq, addr))
> + return -ENOMEM;
> +
> + sg->dma_address = addr;
> + }
> + }
> +
> + for (; n < (out_sgs + in_sgs); n++) {
> + for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> + dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
> +
> + if (vring_mapping_error(vq, addr))
> + return -ENOMEM;
> +
> + sg->dma_address = addr;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static void virtqueue_unmap_sgs(struct vring_virtqueue *vq,
> + struct scatterlist *sgs[],
> + unsigned int total_sg,
> + unsigned int out_sgs,
> + unsigned int in_sgs)
> +{
> + struct scatterlist *sg;
> + unsigned int n;
> +
> + if (!vq->use_dma_api)
> + return;
> +
> + for (n = 0; n < out_sgs; n++) {
> + for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> + if (!sg->dma_address)
> + return;
> +
> + dma_unmap_page(vring_dma_dev(vq), sg->dma_address,
> + sg->length, DMA_TO_DEVICE);
> + }
> + }
> +
> + for (; n < (out_sgs + in_sgs); n++) {
> + for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> + if (!sg->dma_address)
> + return;
> +
> + dma_unmap_page(vring_dma_dev(vq), sg->dma_address,
> + sg->length, DMA_FROM_DEVICE);
> + }
> + }
> +}
> +
> /* note: return NULL means no indirect that is valid. */
> static struct vring_desc *virtqueue_get_desc_split(struct vring_virtqueue *vq,
> unsigned int total_sg,
> @@ -577,7 +644,7 @@ static inline int virtqueue_add_vring_split(struct vring_virtqueue *vq,
> {
> struct virtqueue *_vq = &vq->vq;
> struct scatterlist *sg;
> - unsigned int i, n, avail, descs_used, prev, err_idx;
> + unsigned int i, n, avail, descs_used, prev;
> int head;
> bool indirect;
>
> @@ -598,30 +665,25 @@ static inline int virtqueue_add_vring_split(struct vring_virtqueue *vq,
>
> for (n = 0; n < out_sgs; n++) {
> for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> - dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
> - if (vring_mapping_error(vq, addr))
> - goto unmap_release;
> -
> prev = i;
> /* Note that we trust indirect descriptor
> * table since it use stream DMA mapping.
> */
> - i = virtqueue_add_desc_split(_vq, desc, i, addr, sg->length,
> + i = virtqueue_add_desc_split(_vq, desc, i,
> + sg->dma_address,
> + sg->length,
> VRING_DESC_F_NEXT,
> indirect);
> }
> }
> for (; n < (out_sgs + in_sgs); n++) {
> for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> - dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
> - if (vring_mapping_error(vq, addr))
> - goto unmap_release;
> -
> prev = i;
> /* Note that we trust indirect descriptor
> * table since it use stream DMA mapping.
> */
> - i = virtqueue_add_desc_split(_vq, desc, i, addr,
> + i = virtqueue_add_desc_split(_vq, desc, i,
> + sg->dma_address,
> sg->length,
> VRING_DESC_F_NEXT |
> VRING_DESC_F_WRITE,
> @@ -640,7 +702,7 @@ static inline int virtqueue_add_vring_split(struct vring_virtqueue *vq,
> vq, desc, total_sg * sizeof(struct vring_desc),
> DMA_TO_DEVICE);
> if (vring_mapping_error(vq, addr))
> - goto unmap_release;
> + return -ENOMEM;
>
> virtqueue_add_desc_split(_vq, vq->split.vring.desc,
> head, addr,
> @@ -680,30 +742,6 @@ static inline int virtqueue_add_vring_split(struct vring_virtqueue *vq,
> virtqueue_kick(_vq);
>
> return 0;
> -
> -unmap_release:
> - err_idx = i;
> -
> - if (indirect)
> - i = 0;
> - else
> - i = head;
> -
> - for (n = 0; n < total_sg; n++) {
> - if (i == err_idx)
> - break;
> - if (indirect) {
> - vring_unmap_one_split_indirect(vq, &desc[i]);
> - i = virtio16_to_cpu(_vq->vdev, desc[i].next);
> - } else
> - i = vring_unmap_one_split(vq, i);
> - }
> -
> - if (indirect)
> - kfree(desc);
> -
> - END_USE(vq);
> - return -ENOMEM;
> }
>
> static inline int virtqueue_add_split(struct virtqueue *_vq,
> @@ -729,6 +767,10 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> goto end;
> }
>
> + err = virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
> + if (err)
> + goto err;
> +
> head = vq->free_head;
> err = virtqueue_add_vring_split(vq, sgs, total_sg, out_sgs, in_sgs, desc);
Any reason we don't do virtqueue_map_sgs()/virtqueue_unmap_sgs()
inside virtqueue_add_vring_split()?
Thanks
> if (err)
> @@ -741,6 +783,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> goto end;
>
> err:
> + virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
> +
> kfree(desc);
>
> end:
> --
> 2.32.0.3.g01195cf9f
>
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