[PATCH vhost v2 02/12] virtio_ring: packed: separate dma codes

Xuan Zhuo
2023-03-08T06:44:33Z

DMA-related logic is separated from the virtqueue_add_packed(). DMA
address will be saved as sg->dma_address, then virtqueue_add_packed()
will use it directly. Unmap operation will be simpler.

The purpose of this is to facilitate subsequent support to receive
dma address mapped by drivers.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 37 +++++++-----------------------------
 1 file changed, 7 insertions(+), 30 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 8ace2f503953..b4beb51072f7 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1419,9 +1419,9 @@ static inline int virtqueue_add_packed(struct virtqueue
*_vq,
 	struct vring_virtqueue *vq = to_vvq(_vq);
 	struct vring_packed_desc *desc;
 	struct scatterlist *sg;
-	unsigned int i, n, c, descs_used, err_idx;
+	unsigned int i, n, c, descs_used;
 	__le16 head_flags, flags;
-	u16 head, id, prev, curr, avail_used_flags;
+	u16 head, id, prev, curr;
 	int err;

 	START_USE(vq);
@@ -1450,7 +1450,6 @@ static inline int virtqueue_add_packed(struct virtqueue
*_vq,
 	}

 	head = vq->packed.next_avail_idx;
-	avail_used_flags = vq->packed.avail_used_flags;

 	WARN_ON_ONCE(total_sg > vq->packed.vring.num &&
!vq->indirect);

@@ -1468,15 +1467,13 @@ 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))
+		return -ENOMEM;
+
 	curr = id;
 	c = 0;
 	for (n = 0; 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, n < out_sgs ?
-					DMA_TO_DEVICE : DMA_FROM_DEVICE);
-			if (vring_mapping_error(vq, addr))
-				goto unmap_release;
-
 			flags = cpu_to_le16(vq->packed.avail_used_flags |
 				    (++c == total_sg ? 0 : VRING_DESC_F_NEXT) |
 				    (n < out_sgs ? 0 : VRING_DESC_F_WRITE));
@@ -1485,12 +1482,12 @@ static inline int virtqueue_add_packed(struct virtqueue
*_vq,
 			else
 				desc[i].flags = flags;

-			desc[i].addr = cpu_to_le64(addr);
+			desc[i].addr = cpu_to_le64(sg->dma_address);
 			desc[i].len = cpu_to_le32(sg->length);
 			desc[i].id = cpu_to_le16(id);

 			if (unlikely(vq->use_dma_api)) {
-				vq->packed.desc_extra[curr].addr = addr;
+				vq->packed.desc_extra[curr].addr = sg->dma_address;
 				vq->packed.desc_extra[curr].len = sg->length;
 				vq->packed.desc_extra[curr].flags  					le16_to_cpu(flags);
@@ -1536,26 +1533,6 @@ static inline int virtqueue_add_packed(struct virtqueue
*_vq,
 	END_USE(vq);

 	return 0;
-
-unmap_release:
-	err_idx = i;
-	i = head;
-	curr = vq->free_head;
-
-	vq->packed.avail_used_flags = avail_used_flags;
-
-	for (n = 0; n < total_sg; n++) {
-		if (i == err_idx)
-			break;
-		vring_unmap_extra_packed(vq, &vq->packed.desc_extra[curr]);
-		curr = vq->packed.desc_extra[curr].next;
-		i++;
-		if (i >= vq->packed.vring.num)
-			i = 0;
-	}
-
-	END_USE(vq);
-	return -EIO;
 }

 static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
--
2.32.0.3.g01195cf9f