netdev - [PATCH net-next v3 0/2] virtio-net: avoid conflicts between XDP and GUEST

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Message-Id: <20230626120301.380-1-hengqi@linux.alibaba.com>
Date: Mon, 26 Jun 2023 20:02:59 +0800
From: Heng Qi <hengqi@...ux.alibaba.com>
To: netdev@...r.kernel.org,
	bpf@...r.kernel.org
Cc: "Michael S . Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>
Subject: [PATCH net-next v3 0/2] virtio-net: avoid conflicts between XDP and GUEST_CSUM

virtio-net needs to clear the VIRTIO_NET_F_GUEST_CSUM feature when
loading XDP. The main reason for doing this is because
VIRTIO_NET_F_GUEST_CSUM allows to receive packets marked as
VIRTIO_NET_HDR_F_NEEDS_CSUM. Such packets are not compatible with
XDP programs, because we cannot guarantee that the csum_{start, offset}
fields are correct after XDP modifies the packets.

There is also an existing problem, in the same host vm-vm (eg
[vm]<->[ovs vhost-user]<->[vm]) scenario, loading XDP will cause packet loss.

To solve the above problems, we have discussed in the [1] proposal, and
now try to solve it through the method of reprobing fields suggested
by Jason.

[1] https://lists.oasis-open.org/archives/virtio-dev/202305/msg00318.html

---
v2->v3:
  - Use skb_checksum_setup() instead of virtnet_flow_dissect_udp_tcp().
    The two operations are different, skb_checksum_setup() operates as
    skb->data==>iphdr, and virtnet_flow_dissect_udp_tcp() operates as
    skb->data==>ethhdr. Essentially equivalent. @Jason Wang

v1->v2:
  - Squash v1's patch [1/4] and patch [2/4] into v2's patch [1/3]. @Michael S. Tsirkin
  - Some minor modifications.

Heng Qi (2):
  virtio-net: support coexistence of XDP and GUEST_CSUM
  virtio-net: remove GUEST_CSUM check for XDP

 drivers/net/virtio_net.c | 90 +++++++++++++++++++++++++++++++++-------
 1 file changed, 74 insertions(+), 16 deletions(-)

-- 
2.19.1.6.gb485710b