virtio-net: transmit the multi-buffer xdp

This serves as the basis for XDP_TX and XDP_REDIRECT
to send a multi-buffer xdp_frame.

Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 262d215b15182ce1da4c11913a28fffcf545e3c1..6d3cf8887dd7f8030b945fc0521b55baf546eb0d 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -570,22 +570,43 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
                                   struct xdp_frame *xdpf)
 {
        struct virtio_net_hdr_mrg_rxbuf *hdr;
-       int err;
+       struct skb_shared_info *shinfo;
+       u8 nr_frags = 0;
+       int err, i;
 
        if (unlikely(xdpf->headroom < vi->hdr_len))
                return -EOVERFLOW;
 
-       /* Make room for virtqueue hdr (also change xdpf->headroom?) */
+       if (unlikely(xdp_frame_has_frags(xdpf))) {
+               shinfo = xdp_get_shared_info_from_frame(xdpf);
+               nr_frags = shinfo->nr_frags;
+       }
+
+       /* In wrapping function virtnet_xdp_xmit(), we need to free
+        * up the pending old buffers, where we need to calculate the
+        * position of skb_shared_info in xdp_get_frame_len() and
+        * xdp_return_frame(), which will involve to xdpf->data and
+        * xdpf->headroom. Therefore, we need to update the value of
+        * headroom synchronously here.
+        */
+       xdpf->headroom -= vi->hdr_len;
        xdpf->data -= vi->hdr_len;
        /* Zero header and leave csum up to XDP layers */
        hdr = xdpf->data;
        memset(hdr, 0, vi->hdr_len);
        xdpf->len   += vi->hdr_len;
 
-       sg_init_one(sq->sg, xdpf->data, xdpf->len);
+       sg_init_table(sq->sg, nr_frags + 1);
+       sg_set_buf(sq->sg, xdpf->data, xdpf->len);
+       for (i = 0; i < nr_frags; i++) {
+               skb_frag_t *frag = &shinfo->frags[i];
+
+               sg_set_page(&sq->sg[i + 1], skb_frag_page(frag),
+                           skb_frag_size(frag), skb_frag_off(frag));
+       }
 
-       err = virtqueue_add_outbuf(sq->vq, sq->sg, 1, xdp_to_ptr(xdpf),
-                                  GFP_ATOMIC);
+       err = virtqueue_add_outbuf(sq->vq, sq->sg, nr_frags + 1,
+                                  xdp_to_ptr(xdpf), GFP_ATOMIC);
        if (unlikely(err))
                return -ENOSPC; /* Caller handle free/refcnt */