On Mon, Mar 27, 2023 at 12:05 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> virtio core only supports virtual addresses, dma is completed in virtio
> core.
>
> In some scenarios (such as the AF_XDP), the memory is allocated
> and DMA mapping is completed in advance, so it is necessary for us to
> support passing the DMA address to virtio core.
>
> Drives can use sg->dma_address to pass the mapped dma address to virtio
> core. If one sg->dma_address is used then all sgs must use
> sg->dma_address, otherwise all must be null when passing it to the APIs
> of virtio.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Thanks
> ---
> drivers/virtio/virtio_ring.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 9d6acd59e3e0..2afff1dc6c74 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -81,6 +81,7 @@ struct vring_desc_state_packed {
> struct vring_packed_desc *indir_desc; /* Indirect descriptor, if any. */
> u16 num; /* Descriptor list length. */
> u16 last; /* The last desc state in a list. */
> + u32 flags; /* State flags. */
> };
>
> struct vring_desc_extra {
> @@ -1264,7 +1265,8 @@ static inline u16 packed_last_used(u16 last_used_idx)
> }
>
> static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
> - struct vring_desc_extra *extra)
> + struct vring_desc_extra *extra,
> + bool dma_map_internal)
> {
> u16 flags;
>
> @@ -1279,6 +1281,9 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
> (flags & VRING_DESC_F_WRITE) ?
> DMA_FROM_DEVICE : DMA_TO_DEVICE);
> } else {
> + if (!dma_map_internal)
> + return;
> +
> dma_unmap_page(vring_dma_dev(vq),
> extra->addr, extra->len,
> (flags & VRING_DESC_F_WRITE) ?
> @@ -1445,6 +1450,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
> unsigned int i, n, c, descs_used;
> __le16 head_flags, flags;
> u16 head, id, prev, curr;
> + bool dma_map_internal;
> int err;
>
> START_USE(vq);
> @@ -1490,7 +1496,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
> id = vq->free_head;
> BUG_ON(id == vq->packed.vring.num);
>
> - if (virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs)) {
> + dma_map_internal = !sgs[0]->dma_address;
> + if (dma_map_internal && virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs)) {
> END_USE(vq);
> return -EIO;
> }
> @@ -1544,6 +1551,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
> vq->packed.desc_state[id].data = data;
> vq->packed.desc_state[id].indir_desc = ctx;
> vq->packed.desc_state[id].last = prev;
> + vq->packed.desc_state[id].flags = dma_map_internal ? VRING_STATE_F_MAP_INTERNAL : 0;
>
> /*
> * A driver MUST NOT make the first descriptor in the list
> @@ -1615,8 +1623,10 @@ static void detach_buf_packed(struct vring_virtqueue *vq,
> struct vring_desc_state_packed *state = NULL;
> struct vring_packed_desc *desc;
> unsigned int i, curr;
> + bool dma_map_internal;
>
> state = &vq->packed.desc_state[id];
> + dma_map_internal = !!(state->flags & VRING_STATE_F_MAP_INTERNAL);
>
> /* Clear data ptr. */
> state->data = NULL;
> @@ -1629,7 +1639,8 @@ static void detach_buf_packed(struct vring_virtqueue *vq,
> curr = id;
> for (i = 0; i < state->num; i++) {
> vring_unmap_extra_packed(vq,
> - &vq->packed.desc_extra[curr]);
> + &vq->packed.desc_extra[curr],
> + dma_map_internal);
> curr = vq->packed.desc_extra[curr].next;
> }
> }
> --
> 2.32.0.3.g01195cf9f
>
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