[PATCH 03/33] 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 information in desc_state, we can skip unmap based on this
when executing dma unmap.

Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c | 71 +++++++++++++++++++++++++-----------
 1 file changed, 50 insertions(+), 21 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index ec622403cbd5..25027a35fcf8 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -78,6 +78,7 @@ 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. */
+	bool premapped;
 };
 
 struct vring_desc_extra {
@@ -1200,7 +1201,8 @@ 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 premapped)
 {
 	u16 flags;
 
@@ -1215,6 +1217,9 @@ 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) ?
@@ -1262,7 +1267,8 @@ 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;
@@ -1288,10 +1294,15 @@ 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);
@@ -1350,6 +1361,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 	vq->packed.desc_state[id].data = data;
 	vq->packed.desc_state[id].indir_desc = desc;
 	vq->packed.desc_state[id].last = id;
+	vq->packed.desc_state[id].premapped = premapped;
 
 	vq->num_added += 1;
 
@@ -1359,10 +1371,11 @@ 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);
 
@@ -1377,6 +1390,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 				       unsigned int in_sgs,
 				       void *data,
 				       void *ctx,
+				       bool premapped,
 				       gfp_t gfp)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
@@ -1403,7 +1417,7 @@ 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;
@@ -1435,10 +1449,17 @@ 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) |
@@ -1485,6 +1506,7 @@ 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].premapped = premapped;
 
 	/*
 	 * A driver MUST NOT make the first descriptor in the list
@@ -1501,22 +1523,26 @@ 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;
 }
@@ -1576,8 +1602,10 @@ 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 premapped;
 
 	state = &vq->packed.desc_state[id];
+	premapped = state->premapped;
 
 	/* Clear data ptr. */
 	state->data = NULL;
@@ -1590,7 +1618,8 @@ 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;
 		}
 	}
@@ -1603,7 +1632,7 @@ 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++)
@@ -2122,7 +2151,7 @@ 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, premapped, gfp) :
 				 virtqueue_add_split(_vq, sgs, total_sg,
 					out_sgs, in_sgs, data, ctx, premapped, gfp);
 }
-- 
2.32.0.3.g01195cf9f




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