On Wed, 31 Jan 2024 17:12:47 +0800, Jason Wang [off-list ref] wrote:

On Tue, Jan 30, 2024 at 7:43 PM Xuan Zhuo [off-list ref] wrote:

quoted

If the xsk is enabling, the xsk tx will share the send queue.
But the xsk requires that the send queue use the premapped mode.
So the send queue must support premapped mode.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/net/virtio_net.c | 167 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 163 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 226ab830870e..cf0c67380b07 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -46,6 +46,7 @@ module_param(napi_tx, bool, 0644);
 #define VIRTIO_XDP_REDIR       BIT(1)

 #define VIRTIO_XDP_FLAG        BIT(0)
+#define VIRTIO_DMA_FLAG        BIT(1)

 /* RX packet size EWMA. The average packet size is used to determine the packet
  * buffer size when refilling RX rings. As the entire RX ring may be refilled

@@ -140,6 +141,21 @@ struct virtnet_rq_dma {
        u16 need_sync;
 };

+struct virtnet_sq_dma {
+       union {
+               struct virtnet_sq_dma *next;
+               void *data;
+       };
+       dma_addr_t addr;
+       u32 len;
+       bool is_tail;
+};
+
+struct virtnet_sq_dma_head {
+       struct virtnet_sq_dma *free;
+       struct virtnet_sq_dma *head;

Any reason the head must be a pointer instead of a simple index?

The head is used for kfree.
Maybe I need to rename it.

About the index(next) of the virtnet_sq_dma.
If we use the index, the struct will be:

struct virtnet_sq_dma {
       dma_addr_t addr;
       u32 len;

       u32 next;
       void *data
};

The size of virtnet_sq_dma is same. 

quoted

+};
+
 /* Internal representation of a send virtqueue */
 struct send_queue {
        /* Virtqueue associated with this send _queue */

@@ -159,6 +175,8 @@ struct send_queue {

        /* Record whether sq is in reset state. */
        bool reset;
+
+       struct virtnet_sq_dma_head dmainfo;
 };

....

quoted

+
+static int virtnet_sq_init_dma_mate(struct send_queue *sq)
+{
+       struct virtnet_sq_dma *d;
+       int size, i;
+
+       size = virtqueue_get_vring_size(sq->vq);
+
+       size += MAX_SKB_FRAGS + 2;

Is this enough for the case where an indirect descriptor is used?

This is for the case, when the ring is full, the xmit_skb is called.

I will add comment.

Thanks.

Thanks