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().
This patch stipulates that if sg->dma_address is not NULL, use this
address as the DMA address. And record this information in extra->flags,
which can be skipped when executing dma unmap.
extra->flags |= VRING_DESC_F_PREDMA;
This relies on the previous patch, in the indirect scenario, for each
desc allocated, an extra is allocated at the same time.
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index add8430d9678..e165bc2e1344 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1010,6 +1010,9 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
} else {
+ if (flags & VRING_DESC_F_PREDMA)
+ return;
+
dma_unmap_page(vring_dma_dev(vq),
extra->addr, extra->len,
(flags & VRING_DESC_F_WRITE) ?
@@ -1092,6 +1095,8 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
extra->addr = addr;
extra->len = sg->length;
extra->flags = flags;
+ if (sg_is_predma(sg))
+ extra->flags |= VRING_DESC_F_PREDMA;
i++;
}
@@ -1249,9 +1254,14 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
if (unlikely(vq->use_dma_api)) {
vq->packed.desc_extra[curr].addr = addr;
vq->packed.desc_extra[curr].len = sg->length;
- vq->packed.desc_extra[curr].flags =
- le16_to_cpu(flags);
}
+
+ vq->packed.desc_extra[curr].flags = le16_to_cpu(flags);
+
+ if (sg_is_predma(sg))
+ vq->packed.desc_extra[curr].flags |=
+ VRING_DESC_F_PREDMA;
+
prev = curr;
curr = vq->packed.desc_extra[curr].next;
--
2.31.0
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