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 mapping 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 must be null when passing it to the APIs
of virtio.
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a2a77a0dafe6..cafb720cbdc1 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 dma_map_internal; /* Do dma map internally. */
};
struct vring_desc_extra {
@@ -1259,7 +1260,8 @@ 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 dma_map_internal)
{
u16 flags;
@@ -1274,6 +1276,9 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
} else {
+ if (!dma_map_internal)
+ return;
+
dma_unmap_page(vring_dma_dev(vq),
extra->addr, extra->len,
(flags & VRING_DESC_F_WRITE) ?
@@ -1439,6 +1444,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
unsigned int i, n, c, descs_used;
__le16 head_flags, flags;
u16 head, id, prev, curr;
+ bool dma_map_internal;
int err;
START_USE(vq);
@@ -1484,7 +1490,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
id = vq->free_head;
BUG_ON(id == vq->packed.vring.num);
- if (virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs))
+ dma_map_internal = !sgs[0]->dma_address;
+ if (dma_map_internal && virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs))
return -ENOMEM;
curr = id;
@@ -1536,6 +1543,7 @@ 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].dma_map_internal = dma_map_internal;
/*
* A driver MUST NOT make the first descriptor in the list
@@ -1621,7 +1629,8 @@ 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],
+ state->dma_map_internal);
curr = vq->packed.desc_extra[curr].next;
}
}
--
2.32.0.3.g01195cf9f
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