The virtnet_xdp_handler() is re-used. But

1. We need to copy data to create skb for XDP_PASS.
2. We need to call xsk_buff_free() to release the buffer.
3. The handle for xdp_buff is difference.

If we pushed this logic into existing receive handle(merge and small),
we would have to maintain code scattered inside merge and small (and big).
So I think it is a good choice for us to put the xsk code into an
independent function.

Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
---
 drivers/net/virtio/main.c       |  40 ++++--
 drivers/net/virtio/virtio_net.h |   4 +
 drivers/net/virtio/xsk.c        | 216 ++++++++++++++++++++++++++++++++
 drivers/net/virtio/xsk.h        |   4 +
 4 files changed, 251 insertions(+), 13 deletions(-)

diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
index fb8dbce11e53..35f0daaea7e5 100644
--- a/drivers/net/virtio/main.c
+++ b/drivers/net/virtio/main.c
@@ -801,10 +801,10 @@ static void put_xdp_frags(struct xdp_buff *xdp)
        }
 }
 
-static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
-                              struct net_device *dev,
-                              unsigned int *xdp_xmit,
-                              struct virtnet_rq_stats *stats)
+int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
+                       struct net_device *dev,
+                       unsigned int *xdp_xmit,
+                       struct virtnet_rq_stats *stats)
 {
        struct xdp_frame *xdpf;
        int err;
@@ -1897,23 +1897,37 @@ static int virtnet_receive(struct virtnet_rq *rq, int 
budget,
 {
        struct virtnet_info *vi = rq->vq->vdev->priv;
        struct virtnet_rq_stats stats = {};
+       void *buf, *ctx, *pctx = NULL;
        unsigned int len;
        int packets = 0;
-       void *buf;
        int i;
 
-       if (!vi->big_packets || vi->mergeable_rx_bufs) {
-               void *ctx;
+       if (rq->xsk.pool) {
+               struct sk_buff *skb;
+
+               while (packets < budget) {
+                       buf = virtqueue_get_buf(rq->vq, &len);
+                       if (!buf)
+                               break;
+
+                       skb = virtnet_receive_xsk_buf(vi, rq, buf, len, 
xdp_xmit, &stats);
+                       if (skb)
+                               virtnet_receive_done(vi, rq, skb);
 
-               while (packets < budget &&
-                      (buf = virtnet_rq_get_buf(rq, &len, &ctx))) {
-                       receive_buf(vi, rq, buf, len, ctx, xdp_xmit, &stats);
                        packets++;
                }
        } else {
-               while (packets < budget &&
-                      (buf = virtnet_rq_get_buf(rq, &len, NULL)) != NULL) {
-                       receive_buf(vi, rq, buf, len, NULL, xdp_xmit, &stats);
+               if (!vi->big_packets || vi->mergeable_rx_bufs)
+                       pctx = &ctx;
+               else
+                       ctx = NULL;
+
+               while (packets < budget) {
+                       buf = virtnet_rq_get_buf(rq, &len, pctx);
+                       if (!buf)
+                               break;
+
+                       receive_buf(vi, rq, buf, len, ctx, xdp_xmit, &stats);
                        packets++;
                }
        }
diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h
index c07a1e58bf0f..98dcf1825448 100644
--- a/drivers/net/virtio/virtio_net.h
+++ b/drivers/net/virtio/virtio_net.h
@@ -345,4 +345,8 @@ struct sk_buff *virtnet_skb_append_frag(struct sk_buff 
*head_skb,
                                        struct sk_buff *curr_skb,
                                        struct page *page, void *buf,
                                        int len, int truesize);
+int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
+                       struct net_device *dev,
+                       unsigned int *xdp_xmit,
+                       struct virtnet_rq_stats *stats);
 #endif
diff --git a/drivers/net/virtio/xsk.c b/drivers/net/virtio/xsk.c
index c54cd08e9c77..6f4fa32b1184 100644
--- a/drivers/net/virtio/xsk.c
+++ b/drivers/net/virtio/xsk.c
@@ -14,6 +14,222 @@ static void sg_fill_dma(struct scatterlist *sg, dma_addr_t 
addr, u32 len)
        sg->length = len;
 }
 
+static void xsk_drop_follow_bufs(struct net_device *dev,
+                                struct virtnet_rq *rq,
+                                u32 num_buf,
+                                struct virtnet_rq_stats *stats)
+{
+       struct xdp_buff *xdp;
+       u32 len;
+
+       while (num_buf-- > 1) {
+               xdp = virtqueue_get_buf(rq->vq, &len);
+               if (unlikely(!xdp)) {
+                       pr_debug("%s: rx error: %d buffers missing\n",
+                                dev->name, num_buf);
+                       DEV_STATS_INC(dev, rx_length_errors);
+                       break;
+               }
+               u64_stats_add(&stats->bytes, len);
+               xsk_buff_free(xdp);
+       }
+}
+
+static struct xdp_buff *buf_to_xdp(struct virtnet_info *vi,
+                                  struct virtnet_rq *rq, void *buf, u32 len)
+{
+       struct xdp_buff *xdp;
+       u32 bufsize;
+
+       xdp = (struct xdp_buff *)buf;
+
+       bufsize = xsk_pool_get_rx_frame_size(rq->xsk.pool) + vi->hdr_len;
+
+       if (unlikely(len > bufsize)) {
+               pr_debug("%s: rx error: len %u exceeds truesize %u\n",
+                        vi->dev->name, len, bufsize);
+               DEV_STATS_INC(vi->dev, rx_length_errors);
+               xsk_buff_free(xdp);
+               return NULL;
+       }
+
+       xsk_buff_set_size(xdp, len);
+       xsk_buff_dma_sync_for_cpu(xdp, rq->xsk.pool);
+
+       return xdp;
+}
+
+static int xsk_append_merge_buffer(struct virtnet_info *vi,
+                                  struct virtnet_rq *rq,
+                                  struct sk_buff *head_skb,
+                                  u32 num_buf,
+                                  struct virtio_net_hdr_mrg_rxbuf *hdr,
+                                  struct virtnet_rq_stats *stats)
+{
+       struct sk_buff *curr_skb;
+       struct xdp_buff *xdp;
+       u32 len, truesize;
+       struct page *page;
+       void *buf;
+
+       curr_skb = head_skb;
+
+       while (--num_buf) {
+               buf = virtqueue_get_buf(rq->vq, &len);
+               if (unlikely(!buf)) {
+                       pr_debug("%s: rx error: %d buffers out of %d missing\n",
+                                vi->dev->name, num_buf,
+                                virtio16_to_cpu(vi->vdev,
+                                                hdr->num_buffers));
+                       DEV_STATS_INC(vi->dev, rx_length_errors);
+                       return -EINVAL;
+               }
+
+               u64_stats_add(&stats->bytes, len);
+
+               xdp = buf_to_xdp(vi, rq, buf, len);
+               if (!xdp)
+                       goto err;
+
+               buf = napi_alloc_frag(len);
+               if (!buf) {
+                       xsk_buff_free(xdp);
+                       goto err;
+               }
+
+               memcpy(buf, xdp->data - vi->hdr_len, len);
+
+               xsk_buff_free(xdp);
+
+               page = virt_to_page(buf);
+
+               truesize = len;
+
+               curr_skb  = virtnet_skb_append_frag(head_skb, curr_skb, page,
+                                                   buf, len, truesize);
+               if (!curr_skb) {
+                       put_page(page);
+                       goto err;
+               }
+       }
+
+       return 0;
+
+err:
+       xsk_drop_follow_bufs(vi->dev, rq, num_buf, stats);
+       return -EINVAL;
+}
+
+static struct sk_buff *xdp_construct_skb(struct virtnet_rq *rq,
+                                        struct xdp_buff *xdp)
+{
+       unsigned int metasize = xdp->data - xdp->data_meta;
+       struct sk_buff *skb;
+       unsigned int size;
+
+       size = xdp->data_end - xdp->data_hard_start;
+       skb = napi_alloc_skb(&rq->napi, size);
+       if (unlikely(!skb)) {
+               xsk_buff_free(xdp);
+               return NULL;
+       }
+
+       skb_reserve(skb, xdp->data_meta - xdp->data_hard_start);
+
+       size = xdp->data_end - xdp->data_meta;
+       memcpy(__skb_put(skb, size), xdp->data_meta, size);
+
+       if (metasize) {
+               __skb_pull(skb, metasize);
+               skb_metadata_set(skb, metasize);
+       }
+
+       xsk_buff_free(xdp);
+
+       return skb;
+}
+
+static struct sk_buff *virtnet_receive_xsk_merge(struct net_device *dev, 
struct virtnet_info *vi,
+                                                struct virtnet_rq *rq, struct 
xdp_buff *xdp,
+                                                unsigned int *xdp_xmit,
+                                                struct virtnet_rq_stats *stats)
+{
+       struct virtio_net_hdr_mrg_rxbuf *hdr;
+       struct bpf_prog *prog;
+       struct sk_buff *skb;
+       u32 ret, num_buf;
+
+       hdr = xdp->data - vi->hdr_len;
+       num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
+
+       ret = XDP_PASS;
+       rcu_read_lock();
+       prog = rcu_dereference(rq->xdp_prog);
+       /* TODO: support multi buffer. */
+       if (prog && num_buf == 1)
+               ret = virtnet_xdp_handler(prog, xdp, dev, xdp_xmit, stats);
+       rcu_read_unlock();
+
+       switch (ret) {
+       case XDP_PASS:
+               skb = xdp_construct_skb(rq, xdp);
+               if (!skb)
+                       goto drop_bufs;
+
+               if (xsk_append_merge_buffer(vi, rq, skb, num_buf, hdr, stats)) {
+                       dev_kfree_skb(skb);
+                       goto drop;
+               }
+
+               return skb;
+
+       case XDP_TX:
+       case XDP_REDIRECT:
+               return NULL;
+
+       default:
+               /* drop packet */
+               xsk_buff_free(xdp);
+       }
+
+drop_bufs:
+       xsk_drop_follow_bufs(dev, rq, num_buf, stats);
+
+drop:
+       u64_stats_inc(&stats->drops);
+       return NULL;
+}
+
+struct sk_buff *virtnet_receive_xsk_buf(struct virtnet_info *vi, struct 
virtnet_rq *rq,
+                                       void *buf, u32 len,
+                                       unsigned int *xdp_xmit,
+                                       struct virtnet_rq_stats *stats)
+{
+       struct net_device *dev = vi->dev;
+       struct sk_buff *skb = NULL;
+       struct xdp_buff *xdp;
+
+       len -= vi->hdr_len;
+
+       u64_stats_add(&stats->bytes, len);
+
+       xdp = buf_to_xdp(vi, rq, buf, len);
+       if (!xdp)
+               return NULL;
+
+       if (unlikely(len < ETH_HLEN)) {
+               pr_debug("%s: short packet %i\n", dev->name, len);
+               DEV_STATS_INC(dev, rx_length_errors);
+               xsk_buff_free(xdp);
+               return NULL;
+       }
+
+       if (vi->mergeable_rx_bufs)
+               skb = virtnet_receive_xsk_merge(dev, vi, rq, xdp, xdp_xmit, 
stats);
+
+       return skb;
+}
+
 int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct virtnet_rq *rq,
                            struct xsk_buff_pool *pool, gfp_t gfp)
 {
diff --git a/drivers/net/virtio/xsk.h b/drivers/net/virtio/xsk.h
index bef41a3f954e..e78fcd0a4946 100644
--- a/drivers/net/virtio/xsk.h
+++ b/drivers/net/virtio/xsk.h
@@ -25,4 +25,8 @@ bool virtnet_xsk_xmit(struct virtnet_sq *sq, struct 
xsk_buff_pool *pool,
 int virtnet_xsk_wakeup(struct net_device *dev, u32 qid, u32 flag);
 int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct virtnet_rq *rq,
                            struct xsk_buff_pool *pool, gfp_t gfp);
+struct sk_buff *virtnet_receive_xsk_buf(struct virtnet_info *vi, struct 
virtnet_rq *rq,
+                                       void *buf, u32 len,
+                                       unsigned int *xdp_xmit,
+                                       struct virtnet_rq_stats *stats);
 #endif
-- 
2.32.0.3.g01195cf9f


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