[PATCH v2 6/9] virtio_ring: packed: virtqueue_add_packed() support premapped

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virtqueue_add_packed() only supports virtual addresses, dma is completed
in virtqueue_add_packed().

In some scenarios (such as the AF_XDP scenario), the memory is allocated
and DMA is completed in advance, so it is necessary for us to support
passing the DMA address to virtqueue_add_packed().

Record this premapped information in desc_extra[id]->premapped, which
can be skipped when executing dma unmap.

Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c | 76 +++++++++++++++++++++++++-----------
 1 file changed, 54 insertions(+), 22 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 35cb804dcf2d..c8d63cae8b33 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1007,7 +1007,8 @@ static struct virtqueue *vring_create_virtqueue_split(
  */
 
 static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
-				     struct vring_desc_extra *extra)
+				     struct vring_desc_extra *extra,
+				     bool premapped)
 {
 	u16 flags;
 
@@ -1022,6 +1023,9 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
 				 (flags & VRING_DESC_F_WRITE) ?
 				 DMA_FROM_DEVICE : DMA_TO_DEVICE);
 	} else {
+		if (premapped)
+			return;
+
 		dma_unmap_page(vring_dma_dev(vq),
 			       extra->addr, extra->len,
 			       (flags & VRING_DESC_F_WRITE) ?
@@ -1069,7 +1073,8 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 					 unsigned int out_sgs,
 					 unsigned int in_sgs,
 					 void *data,
-					 gfp_t gfp)
+					 gfp_t gfp,
+					 bool premapped)
 {
 	struct vring_packed_desc *desc;
 	struct scatterlist *sg;
@@ -1095,10 +1100,15 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 
 	for (n = 0; n < out_sgs + in_sgs; n++) {
 		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
-			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;
+			if (premapped) {
+				addr = sg_dma_address(sg);
+
+			} else {
+				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;
+			}
 
 			desc[i].flags = cpu_to_le16(n < out_sgs ?
 						0 : VRING_DESC_F_WRITE);
@@ -1128,6 +1138,8 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 						  vq->packed.avail_used_flags;
 	}
 
+	vq->packed.desc_extra[id].premapped = premapped;
+
 	/*
 	 * A driver MUST NOT make the first descriptor in the list
 	 * available before all subsequent descriptors comprising
@@ -1166,10 +1178,11 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 	return 0;
 
 unmap_release:
-	err_idx = i;
-
-	for (i = 0; i < err_idx; i++)
-		vring_unmap_desc_packed(vq, &desc[i]);
+	if (!premapped) {
+		err_idx = i;
+		for (i = 0; i < err_idx; i++)
+			vring_unmap_desc_packed(vq, &desc[i]);
+	}
 
 	kfree(desc);
 
@@ -1184,7 +1197,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 				       unsigned int in_sgs,
 				       void *data,
 				       void *ctx,
-				       gfp_t gfp)
+				       gfp_t gfp,
+				       bool premapped)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 	struct vring_packed_desc *desc;
@@ -1210,7 +1224,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 
 	if (virtqueue_use_indirect(_vq, total_sg)) {
 		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
-						    in_sgs, data, gfp);
+						    in_sgs, data, gfp, premapped);
 		if (err != -ENOMEM) {
 			END_USE(vq);
 			return err;
@@ -1242,10 +1256,17 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 	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;
+			dma_addr_t addr;
+
+			if (premapped) {
+				addr = sg_dma_address(sg);
+
+			} else {
+				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) |
@@ -1265,6 +1286,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 				vq->packed.desc_extra[curr].flags =
 					le16_to_cpu(flags);
 			}
+
 			prev = curr;
 			curr = vq->packed.desc_extra[curr].next;
 
@@ -1293,6 +1315,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 	vq->packed.desc_state[id].indir_desc = ctx;
 	vq->packed.desc_state[id].last = prev;
 
+	vq->packed.desc_extra[id].premapped = premapped;
+
 	/*
 	 * A driver MUST NOT make the first descriptor in the list
 	 * available before all subsequent descriptors comprising
@@ -1308,22 +1332,26 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 	return 0;
 
 unmap_release:
+	vq->packed.avail_used_flags = avail_used_flags;
+
+	if (premapped)
+		goto unmap_free;
+
 	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]);
+		vring_unmap_extra_packed(vq, &vq->packed.desc_extra[curr], false);
 		curr = vq->packed.desc_extra[curr].next;
 		i++;
 		if (i >= vq->packed.vring.num)
 			i = 0;
 	}
 
+unmap_free:
 	END_USE(vq);
 	return -EIO;
 }
@@ -1383,9 +1411,12 @@ 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 premapped;
 
 	state = &vq->packed.desc_state[id];
 
+	premapped = vq->packed.desc_extra[state->last].premapped;
+
 	/* Clear data ptr. */
 	state->data = NULL;
 
@@ -1397,7 +1428,8 @@ 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],
+						 premapped);
 			curr = vq->packed.desc_extra[curr].next;
 		}
 	}
@@ -1410,7 +1442,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq,
 		if (!desc)
 			return;
 
-		if (vq->use_dma_api) {
+		if (vq->use_dma_api && !premapped) {
 			len = vq->packed.desc_extra[id].len;
 			for (i = 0; i < len / sizeof(struct vring_packed_desc);
 					i++)
@@ -1816,7 +1848,7 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
 	return vq->packed_ring ? virtqueue_add_packed(_vq, sgs, total_sg,
-					out_sgs, in_sgs, data, ctx, gfp) :
+					out_sgs, in_sgs, data, ctx, gfp, premapped) :
 				 virtqueue_add_split(_vq, sgs, total_sg,
 					out_sgs, in_sgs, data, ctx, gfp, premapped);
 }
-- 
2.31.0

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