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Message-ID: <d1ebd2a7-10e7-354b-1256-02520c7d29cb@linux.alibaba.com>
Date: Fri, 13 Jan 2023 10:59:51 +0800
From: Heng Qi <hengqi@...ux.alibaba.com>
To: Jason Wang <jasowang@...hat.com>, netdev@...r.kernel.org,
bpf@...r.kernel.org
Cc: "Michael S . Tsirkin" <mst@...hat.com>,
Paolo Abeni <pabeni@...hat.com>,
Jakub Kicinski <kuba@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
"David S . Miller" <davem@...emloft.net>,
Daniel Borkmann <daniel@...earbox.net>,
Alexei Starovoitov <ast@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Subject: Re: [PATCH v3 2/9] virtio-net: set up xdp for multi buffer packets
在 2023/1/13 上午10:49, Jason Wang 写道:
>
> 在 2023/1/3 14:40, Heng Qi 写道:
>> When the xdp program sets xdp.frags, which means it can process
>> multi-buffer packets over larger MTU, so we continue to support xdp.
>> But for single-buffer xdp, we should keep checking for MTU.
>>
>> Signed-off-by: Heng Qi <hengqi@...ux.alibaba.com>
>> Reviewed-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
>> ---
>> drivers/net/virtio_net.c | 10 ++++++----
>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 443aa7b8f0ad..60e199811212 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -3074,7 +3074,9 @@ static int
>> virtnet_restore_guest_offloads(struct virtnet_info *vi)
>> static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog
>> *prog,
>> struct netlink_ext_ack *extack)
>> {
>> - unsigned long int max_sz = PAGE_SIZE - sizeof(struct
>> padded_vnet_hdr);
>> + unsigned int room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM +
>> + sizeof(struct skb_shared_info));
>> + unsigned int max_sz = PAGE_SIZE - room - ETH_HLEN;
>> struct virtnet_info *vi = netdev_priv(dev);
>> struct bpf_prog *old_prog;
>> u16 xdp_qp = 0, curr_qp;
>> @@ -3095,9 +3097,9 @@ static int virtnet_xdp_set(struct net_device
>> *dev, struct bpf_prog *prog,
>> return -EINVAL;
>> }
>> - if (dev->mtu > max_sz) {
>> - NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP");
>> - netdev_warn(dev, "XDP requires MTU less than %lu\n", max_sz);
>> + if (prog && !prog->aux->xdp_has_frags && dev->mtu > max_sz) {
>> + NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP
>> without frags");
>> + netdev_warn(dev, "single-buffer XDP requires MTU less than
>> %u\n", max_sz);
>> return -EINVAL;
>> }
>
>
> I think we probably need to backport this to -stable. So I suggest to
> move/squash the check of !prog->aux->xdp_has_frags to one of the
> following patch.
Sure, and you are right.
Thanks.
>
> With this,
>
> Acked-by: Jason Wang <jasowang@...hat.com>
>
> Thanks
>
>
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