[PATCH vhost v10 03/10] virtio_ring: split: support add premapped buf

From: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
To: virtualization@lists.linux-foundation.org
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH vhost v10 03/10] virtio_ring: split: support add premapped buf
Date: Fri,  2 Jun 2023 17:21:59 +0800	[thread overview]
Message-ID: <20230602092206.50108-4-xuanzhuo@linux.alibaba.com> (raw)
In-Reply-To: <20230602092206.50108-1-xuanzhuo@linux.alibaba.com>

If the vq is the premapped mode, use the sg_dma_address() directly.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 46 ++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 18 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 2afdfb9e3e30..18212c3e056b 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -598,8 +598,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
 			dma_addr_t addr;
 
-			if (vring_map_one_sg(vq, sg, DMA_TO_DEVICE, &addr))
-				goto unmap_release;
+			if (vq->premapped) {
+				addr = sg_dma_address(sg);
+			} else {
+				if (vring_map_one_sg(vq, sg, DMA_TO_DEVICE, &addr))
+					goto unmap_release;
+			}
 
 			prev = i;
 			/* Note that we trust indirect descriptor
@@ -614,8 +618,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
 			dma_addr_t addr;
 
-			if (vring_map_one_sg(vq, sg, DMA_FROM_DEVICE, &addr))
-				goto unmap_release;
+			if (vq->premapped) {
+				addr = sg_dma_address(sg);
+			} else {
+				if (vring_map_one_sg(vq, sg, DMA_FROM_DEVICE, &addr))
+					goto unmap_release;
+			}
 
 			prev = i;
 			/* Note that we trust indirect descriptor
@@ -689,21 +697,23 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 	return 0;
 
 unmap_release:
-	err_idx = i;
+	if (!vq->premapped) {
+		err_idx = i;
 
-	if (indirect)
-		i = 0;
-	else
-		i = head;
-
-	for (n = 0; n < total_sg; n++) {
-		if (i == err_idx)
-			break;
-		if (indirect) {
-			vring_unmap_one_split_indirect(vq, &desc[i]);
-			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
-		} else
-			i = vring_unmap_one_split(vq, i);
+		if (indirect)
+			i = 0;
+		else
+			i = head;
+
+		for (n = 0; n < total_sg; n++) {
+			if (i == err_idx)
+				break;
+			if (indirect) {
+				vring_unmap_one_split_indirect(vq, &desc[i]);
+				i = virtio16_to_cpu(_vq->vdev, desc[i].next);
+			} else
+				i = vring_unmap_one_split(vq, i);
+		}
 	}
 
 	if (indirect)
-- 
2.32.0.3.g01195cf9f

