virtio_ring: support add premapped buf

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

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Message-Id: <20230810123057.43407-5-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 8e81b01..f9f772e 100644 (file)
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -361,6 +361,11 @@ static struct device *vring_dma_dev(const struct vring_virtqueue *vq)
 static int vring_map_one_sg(const struct vring_virtqueue *vq, struct scatterlist *sg,
                            enum dma_data_direction direction, dma_addr_t *addr)
 {
+       if (vq->premapped) {
+               *addr = sg_dma_address(sg);
+               return 0;
+       }
+
        if (!vq->use_dma_api) {
                /*
                 * If DMA is not used, KMSAN doesn't know that the scatterlist
@@ -639,8 +644,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
                dma_addr_t addr = vring_map_single(
                        vq, desc, total_sg * sizeof(struct vring_desc),
                        DMA_TO_DEVICE);
-               if (vring_mapping_error(vq, addr))
+               if (vring_mapping_error(vq, addr)) {
+                       if (vq->premapped)
+                               goto free_indirect;
+
                        goto unmap_release;
+               }
 
                virtqueue_add_desc_split(_vq, vq->split.vring.desc,
                                         head, addr,
@@ -706,6 +715,7 @@ unmap_release:
                        i = vring_unmap_one_split(vq, i);
        }
 
+free_indirect:
        if (indirect)
                kfree(desc);
 
@@ -1307,8 +1317,12 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
        addr = vring_map_single(vq, desc,
                        total_sg * sizeof(struct vring_packed_desc),
                        DMA_TO_DEVICE);
-       if (vring_mapping_error(vq, addr))
+       if (vring_mapping_error(vq, addr)) {
+               if (vq->premapped)
+                       goto free_desc;
+
                goto unmap_release;
+       }
 
        vq->packed.vring.desc[head].addr = cpu_to_le64(addr);
        vq->packed.vring.desc[head].len = cpu_to_le32(total_sg *
@@ -1366,6 +1380,7 @@ unmap_release:
        for (i = 0; i < err_idx; i++)
                vring_unmap_desc_packed(vq, &desc[i]);
 
+free_desc:
        kfree(desc);
 
        END_USE(vq);