On Thu, 21 Mar 2024 12:47:18 +0800, Jason Wang [off-list ref] wrote:

On Tue, Mar 12, 2024 at 11:36 AM Xuan Zhuo [off-list ref] wrote:

quoted

This commit structure the indirect desc table.
Then we can get the desc num directly when doing unmap.

And save the dma info to the struct, then the indirect
will not use the dma fields of the desc_extra. The subsequent
commits will make the dma fields are optional. But for
the indirect case, we must record the dma info.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 66 +++++++++++++++++++++---------------
 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 0dfbd17e5a87..22a588bba166 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c

@@ -72,9 +72,16 @@ struct vring_desc_state_split {
        struct vring_desc *indir_desc;  /* Indirect descriptor, if any. */
 };

+struct vring_packed_desc_indir {
+       dma_addr_t addr;                /* Descriptor Array DMA addr. */
+       u32 len;                        /* Descriptor Array length. */
+       u32 num;
+       struct vring_packed_desc desc[];
+};
+
 struct vring_desc_state_packed {
        void *data;                     /* Data for callback. */
-       struct vring_packed_desc *indir_desc; /* Indirect descriptor, if any. */
+       struct vring_packed_desc_indir *indir_desc; /* Indirect descriptor, if any. */

Maybe it's better just to have a vring_desc_extra here.

Do you mean replacing vring_packed_desc_indir by vring_desc_extra?

I am ok for that. But vring_desc_extra has two extra items:

	u16 flags;			/* Descriptor flags. */
	u16 next;			/* The next desc state in a list. */

vring_packed_desc_indir has "desc". I think that is more convenient.

So, I think vring_packed_desc_indir is appropriate.
Or I missed something.


Thanks.

Thanks