[PATCH net-next v8 08/10] virtio_net: xsk: rx: support fill with xsk buffer

[Xuan Zhuo]

Implement the logic of filling rq with XSK buffers.

Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
---

v8:
   1. update comment
   2. return err from virtnet_add_recvbuf_xsk() when encounters error

 drivers/net/virtio_net.c | 70 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 66 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 665b4925e545..a908f5e72677 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -354,6 +354,8 @@ struct receive_queue {

        /* xdp rxq used by xsk */
        struct xdp_rxq_info xsk_rxq_info;
+
+       struct xdp_buff **xsk_buffs;
 };

 /* This structure can contain rss message with maximum settings for 
indirection table and keysize
@@ -1054,6 +1056,53 @@ static void check_sq_full_and_disable(struct 
virtnet_info *vi,
        }
 }

+static void sg_fill_dma(struct scatterlist *sg, dma_addr_t addr, u32 len)
+{
+       sg->dma_address = addr;
+       sg->length = len;
+}
+
+static int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct 
receive_queue *rq,
+                                  struct xsk_buff_pool *pool, gfp_t gfp)
+{
+       struct xdp_buff **xsk_buffs;
+       dma_addr_t addr;
+       int err = 0;
+       u32 len, i;
+       int num;
+
+       xsk_buffs = rq->xsk_buffs;
+
+       num = xsk_buff_alloc_batch(pool, xsk_buffs, rq->vq->num_free);
+       if (!num)
+               return -ENOMEM;
+
+       len = xsk_pool_get_rx_frame_size(pool) + vi->hdr_len;
+
+       for (i = 0; i < num; ++i) {
+               /* Use the part of XDP_PACKET_HEADROOM as the virtnet hdr space.
+                * We assume XDP_PACKET_HEADROOM is larger than hdr->len.
+                * (see function virtnet_xsk_pool_enable)
+                */
+               addr = xsk_buff_xdp_get_dma(xsk_buffs[i]) - vi->hdr_len;
+
+               sg_init_table(rq->sg, 1);
+               sg_fill_dma(rq->sg, addr, len);
+
+               err = virtqueue_add_inbuf(rq->vq, rq->sg, 1, xsk_buffs[i], gfp);
+               if (err)
+                       goto err;
+       }
+
+       return num;
+
+err:
+       for (; i < num; ++i)
+               xsk_buff_free(xsk_buffs[i]);
+
+       return err;
+}
+
 static int virtnet_xsk_wakeup(struct net_device *dev, u32 qid, u32 flag)
 {
        struct virtnet_info *vi = netdev_priv(dev);
@@ -2245,7 +2294,11 @@ static bool try_fill_recv(struct virtnet_info *vi, 
struct receive_queue *rq,
                          gfp_t gfp)
 {
        int err;
-       bool oom;
+
+       if (rq->xsk_pool) {
+               err = virtnet_add_recvbuf_xsk(vi, rq, rq->xsk_pool, gfp);
+               goto kick;
+       }

        do {
                if (vi->mergeable_rx_bufs)
@@ -2255,10 +2308,11 @@ static bool try_fill_recv(struct virtnet_info *vi, 
struct receive_queue *rq,
                else
                        err = add_recvbuf_small(vi, rq, gfp);

-               oom = err == -ENOMEM;
                if (err)
                        break;
        } while (rq->vq->num_free);
+
+kick:
        if (virtqueue_kick_prepare(rq->vq) && virtqueue_notify(rq->vq)) {
                unsigned long flags;

@@ -2267,7 +2321,7 @@ static bool try_fill_recv(struct virtnet_info *vi, struct 
receive_queue *rq,
                u64_stats_update_end_irqrestore(&rq->stats.syncp, flags);
        }

-       return !oom;
+       return err != -ENOMEM;
 }

 static void skb_recv_done(struct virtqueue *rvq)
@@ -5104,7 +5158,7 @@ static int virtnet_xsk_pool_enable(struct net_device *dev,
        struct receive_queue *rq;
        struct device *dma_dev;
        struct send_queue *sq;
-       int err;
+       int err, size;

        if (vi->hdr_len > xsk_pool_get_headroom(pool))
                return -EINVAL;
@@ -5135,6 +5189,12 @@ static int virtnet_xsk_pool_enable(struct net_device 
*dev,
        if (!dma_dev)
                return -EINVAL;

+       size = virtqueue_get_vring_size(rq->vq);
+
+       rq->xsk_buffs = kvcalloc(size, sizeof(*rq->xsk_buffs), GFP_KERNEL);
+       if (!rq->xsk_buffs)
+               return -ENOMEM;
+
        err = xsk_pool_dma_map(pool, dma_dev, 0);
        if (err)
                goto err_xsk_map;
@@ -5169,6 +5229,8 @@ static int virtnet_xsk_pool_disable(struct net_device 
*dev, u16 qid)

        xsk_pool_dma_unmap(pool, 0);

+       kvfree(rq->xsk_buffs);
+
        return err;
 }

--
2.32.0.3.g01195cf9f