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| author | Jason Wang <jasowang@redhat.com> | 2025-12-30 09:46:44 +0300 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2025-12-31 13:39:18 +0300 |
| commit | 03f05c4eeb7bc5019deb25f7415a7af8dc3fdd3f (patch) | |
| tree | aaa28eff7cd7902a68497966a6a31b5369701701 | |
| parent | 1208473f9b5eb273e787bb1b07a4b2a323692a10 (diff) | |
| download | linux-03f05c4eeb7bc5019deb25f7415a7af8dc3fdd3f.tar.xz | |
virtio_ring: determine descriptor flags at one time
Let's determine the last descriptor by counting the number of sg. This
would be consistent with packed virtqueue implementation and ease the
future in-order implementation.
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20251230064649.55597-15-jasowang@redhat.com>
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 28 |
1 files changed, 13 insertions, 15 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index d0904ac0aa93..e55b26a03037 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -574,7 +574,7 @@ static inline int virtqueue_add_split(struct vring_virtqueue *vq, struct vring_desc_extra *extra; struct scatterlist *sg; struct vring_desc *desc; - unsigned int i, n, avail, descs_used, prev, err_idx; + unsigned int i, n, avail, descs_used, err_idx, sg_count = 0; int head; bool indirect; @@ -634,42 +634,40 @@ static inline int virtqueue_add_split(struct vring_virtqueue *vq, for (sg = sgs[n]; sg; sg = sg_next(sg)) { dma_addr_t addr; u32 len; + u16 flags = 0; + + if (++sg_count != total_sg) + flags |= VRING_DESC_F_NEXT; if (vring_map_one_sg(vq, sg, DMA_TO_DEVICE, &addr, &len, premapped)) 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, extra, i, addr, len, - VRING_DESC_F_NEXT, - premapped); + i = virtqueue_add_desc_split(vq, desc, extra, i, addr, + len, flags, premapped); } } for (; n < (out_sgs + in_sgs); n++) { for (sg = sgs[n]; sg; sg = sg_next(sg)) { dma_addr_t addr; u32 len; + u16 flags = VRING_DESC_F_WRITE; + + if (++sg_count != total_sg) + flags |= VRING_DESC_F_NEXT; if (vring_map_one_sg(vq, sg, DMA_FROM_DEVICE, &addr, &len, premapped)) 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, extra, i, addr, len, - VRING_DESC_F_NEXT | - VRING_DESC_F_WRITE, - premapped); + i = virtqueue_add_desc_split(vq, desc, extra, i, addr, + len, flags, premapped); } } - /* Last one doesn't continue. */ - desc[prev].flags &= cpu_to_virtio16(vq->vq.vdev, ~VRING_DESC_F_NEXT); - if (!indirect && vring_need_unmap_buffer(vq, &extra[prev])) - vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &= - ~VRING_DESC_F_NEXT; if (indirect) { /* Now that the indirect table is filled in, map it. */ |