From: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
Date: Fri, 17 Nov 2017 17:59:13 -0500
> Tuntap and similar devices can inject GSO packets. Accept type
> VIRTIO_NET_HDR_GSO_UDP, even though not generating UFO natively.
>
> Processes are expected to use feature negotiation such as TUNSETOFFLOAD
> to detect supported offload types and refrain from injecting other
> packets. This process breaks down with live migration: guest kernels
> do not renegotiate flags, so destination hosts need to expose all
> features that the source host does.
>
> Partially revert the UFO removal from 182e0b6b5846~1..d9d30adf5677.
> This patch introduces nearly(*) no new code to simplify verification.
> It brings back verbatim tuntap UFO negotiation, VIRTIO_NET_HDR_GSO_UDP
> insertion and software UFO segmentation.
This looks good, one minor nit:
> @@ -2369,6 +2369,10 @@ static int set_offload(struct tun_struct *tun,
> unsigned long arg)
> features |= NETIF_F_TSO6;
> arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
> }
> +
> + if (arg & TUN_F_UFO) {
> + arg &= ~TUN_F_UFO;
> + }
This can be just simply "arg &= ~TUN_F_UFO;"? If anything the curly braces
should be removed for a single statement basic block.
Thanks for working so hard on fixing this.
