@@ -965,6 +965,24 @@ static struct sk_buff *receive_mergeable
* xdp.data_meta were adjusted
*/
len = xdp.data_end - xdp.data + vi->hdr_len + metasize;
+
+ /* recalculate headroom if xdp.data or xdp_data_meta
+ * were adjusted, note that offset should always point
+ * to the start of the reserved bytes for virtio_net
+ * header which are followed by xdp.data, that means
+ * that offset is equal to the headroom (when buf is
+ * starting at the beginning of the page, otherwise
+ * there is a base offset inside the page) but it's used
+ * with a different starting point (buf start) than
+ * xdp.data (buf start + vnet hdr size). If xdp.data or
+ * data_meta were adjusted by the xdp prog then the
+ * headroom size has changed and so has the offset, we
+ * can use data_hard_start, which points at buf start +
+ * vnet hdr size, to calculate the new headroom and use
+ * it later to compute buf start in page_to_skb()
+ */
+ headroom = xdp.data - xdp.data_hard_start - metasize;
+
/* We can only create skb based on xdp_page. */
if (unlikely(xdp_page != page)) {
rcu_read_unlock();
@@ -972,7 +990,7 @@ static struct sk_buff *receive_mergeable
head_skb = page_to_skb(vi, rq, xdp_page, offset,
len, PAGE_SIZE, false,
metasize,
- VIRTIO_XDP_HEADROOM);
+ headroom);
return head_skb;
}
break;