diff mbox series

[v3,7/9] virtio-net: build skb from multi-buffer xdp

Message ID 20230103064012.108029-8-hengqi@linux.alibaba.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series virtio-net: support multi buffer xdp | expand

Checks

Context Check Description
netdev/tree_selection success Guessed tree name to be net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix warning Target tree name not specified in the subject
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit fail Errors and warnings before: 0 this patch: 1
netdev/cc_maintainers warning 2 maintainers not CCed: virtualization@lists.linux-foundation.org hawk@kernel.org
netdev/build_clang fail Errors and warnings before: 0 this patch: 2
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn fail Errors and warnings before: 0 this patch: 1
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 55 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Heng Qi Jan. 3, 2023, 6:40 a.m. UTC 
This converts the xdp_buff directly to a skb, including
multi-buffer and single buffer xdp. We'll isolate the
construction of skb based on xdp from page_to_skb().

Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/virtio_net.c | 49 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
diff mbox series

Patch

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index fee9ce31f6c7..87d65b7a5033 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -952,6 +952,55 @@  static struct sk_buff *receive_big(struct net_device *dev,
 	return NULL;
 }
 
+/* Why not use xdp_build_skb_from_frame() ?
+ * XDP core assumes that xdp frags are PAGE_SIZE in length, while in
+ * virtio-net there are 2 points that do not match its requirements:
+ *  1. The size of the prefilled buffer is not fixed before xdp is set.
+ *  2. xdp_build_skb_from_frame() does more checks that we don't need,
+ *     like eth_type_trans() (which virtio-net does in receive_buf()).
+ */
+static struct sk_buff *build_skb_from_xdp_buff(struct net_device *dev,
+					       struct virtnet_info *vi,
+					       struct xdp_buff *xdp,
+					       unsigned int xdp_frags_truesz)
+{
+	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
+	unsigned int headroom, data_len;
+	struct sk_buff *skb;
+	int metasize;
+	u8 nr_frags;
+
+	if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {
+		pr_debug("Error building skb as missing reserved tailroom for xdp");
+		return NULL;
+	}
+
+	if (unlikely(xdp_buff_has_frags(xdp)))
+		nr_frags = sinfo->nr_frags;
+
+	skb = build_skb(xdp->data_hard_start, xdp->frame_sz);
+	if (unlikely(!skb))
+		return NULL;
+
+	headroom = xdp->data - xdp->data_hard_start;
+	data_len = xdp->data_end - xdp->data;
+	skb_reserve(skb, headroom);
+	__skb_put(skb, data_len);
+
+	metasize = xdp->data - xdp->data_meta;
+	metasize = metasize > 0 ? metasize : 0;
+	if (metasize)
+		skb_metadata_set(skb, metasize);
+
+	if (unlikely(xdp_buff_has_frags(xdp)))
+		xdp_update_skb_shared_info(skb, nr_frags,
+					   sinfo->xdp_frags_size,
+					   xdp_frags_truesz,
+					   xdp_buff_is_frag_pfmemalloc(xdp));
+
+	return skb;
+}
+
 /* TODO: build xdp in big mode */
 static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 				      struct virtnet_info *vi,