On Fri, Jun 2, 2023 at 5:22 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> If the vq is the premapped mode, use the sg_dma_address() directly.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_ring.c | 46 ++++++++++++++++++++++--------------
> 1 file changed, 28 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 2afdfb9e3e30..18212c3e056b 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -598,8 +598,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> dma_addr_t addr;
>
> - if (vring_map_one_sg(vq, sg, DMA_TO_DEVICE, &addr))
> - goto unmap_release;
> + if (vq->premapped) {
> + addr = sg_dma_address(sg);
> + } else {
> + if (vring_map_one_sg(vq, sg, DMA_TO_DEVICE, &addr))
> + goto unmap_release;
> + }
Btw, I wonder whether or not it would be simple to implement the
vq->premapped check inside vring_map_one_sg() assuming the
!use_dma_api is done there as well.
>
> prev = i;
> /* Note that we trust indirect descriptor
> @@ -614,8 +618,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> dma_addr_t addr;
>
> - if (vring_map_one_sg(vq, sg, DMA_FROM_DEVICE, &addr))
> - goto unmap_release;
> + if (vq->premapped) {
> + addr = sg_dma_address(sg);
> + } else {
> + if (vring_map_one_sg(vq, sg, DMA_FROM_DEVICE, &addr))
> + goto unmap_release;
> + }
>
> prev = i;
> /* Note that we trust indirect descriptor
> @@ -689,21 +697,23 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> return 0;
>
> unmap_release:
> - err_idx = i;
> + if (!vq->premapped) {
Can vq->premapped be true here? The label is named as "unmap_relase"
which implies "map" beforehand which seems not the case for
premapping.
Thanks
> + 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)
> + 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)
> --
> 2.32.0.3.g01195cf9f
>
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