virtio core only supports virtual addresses, dma is completed in virtio
core.
In some scenarios (such as the AF_XDP), the memory is allocated
and DMA is completed in advance, so it is necessary for us to support
passing the DMA address to virtio core.
Drives can use sg->dma_address to pass the mapped dma address to virtio
core. If one sg->dma_address is used then all sgs must use sg->dma_address,
otherwise all dma_address must be null.
On the indirect path, if dma_address is used, desc_state.indir_desc will
be mixed with VRING_INDIRECT_PREMAPPED. So when do unmap, we can pass it.
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 66a071e3bdef..11827d2e56a8 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -231,6 +231,18 @@ static void vring_free(struct virtqueue *_vq);
* Helpers.
*/
+#define VRING_INDIRECT_PREMAPPED BIT(0)
+
+#define desc_mix_dma_map(do_map, desc) \
+ (do_map ? desc : (typeof(desc))((unsigned long)(desc) | VRING_INDIRECT_PREMAPPED))
+
+#define desc_rm_dma_map(desc) \
+ ((typeof(desc))((unsigned long)(desc) & ~VRING_INDIRECT_PREMAPPED))
+
+#define desc_map_inter(desc) \
+ !((unsigned long)(desc) & VRING_INDIRECT_PREMAPPED)
+
+
#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
static inline bool virtqueue_use_indirect(struct vring_virtqueue *vq,
@@ -725,7 +737,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
/* Store token and indirect buffer state. */
vq->split.desc_state[head].data = data;
if (indirect)
- vq->split.desc_state[head].indir_desc = desc;
+ vq->split.desc_state[head].indir_desc = desc_mix_dma_map(do_map, desc);
else
vq->split.desc_state[head].indir_desc = ctx;
@@ -820,22 +832,26 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
vq->vq.num_free++;
if (vq->indirect) {
- struct vring_desc *indir_desc =
- vq->split.desc_state[head].indir_desc;
+ struct vring_desc *mix = vq->split.desc_state[head].indir_desc;
+ struct vring_desc *indir_desc;
u32 len;
/* Free the indirect table, if any, now that it's unmapped. */
- if (!indir_desc)
+ if (!mix)
return;
+ indir_desc = desc_rm_dma_map(mix);
+
len = vq->split.desc_extra[head].len;
BUG_ON(!(vq->split.desc_extra[head].flags &
VRING_DESC_F_INDIRECT));
BUG_ON(len == 0 || len % sizeof(struct vring_desc));
- for (j = 0; j < len / sizeof(struct vring_desc); j++)
- vring_unmap_one_split_indirect(vq, &indir_desc[j]);
+ if (desc_map_inter(mix)) {
+ for (j = 0; j < len / sizeof(struct vring_desc); j++)
+ vring_unmap_one_split_indirect(vq, &indir_desc[j]);
+ }
kfree(indir_desc);
vq->split.desc_state[head].indir_desc = NULL;
--
2.32.0.3.g01195cf9f
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