RE: [virtio-dev] RE: [PATCH v15] virtio-net: support inner header hash

[Parav Pandit <parav@nvidia.com>]

> From: Michael S. Tsirkin <mst@redhat.com>
> Sent: Thursday, June 8, 2023 10:42 AM

> > > 2. hand over to RSS the ability to specify a hash based on the outer source
> port.
> > > That is, we can add VIRTIO_NET_RSS_HASH_TUNNEL_SRC_PORT_UDP_{v4,
> v6,
> > > EX} in \field{supported_hash_types} to indicate that the hash should
> > > be calculated using the outer source port for all UDP tunneling protocols.
> > > This approach removes the need for \field{hash_option} and makes the
> > > line between VIRTIO_NET_F_HASH_TUNNEL and VIRTIO_NET_F_RSS clearer.
> > >
> > #2 is preferred.
> >
> > But I must be missing something.
> > Without VIRTIO_NET_RSS_HASH_TUNNEL_SRC_PORT_UDP_X, today if one
> wants
> > to do RSS based on the outer UDP ports, It is already supported by the RSS
> (even in presence of the inner header).
> >
> > So why do have to introduce
> VIRTIO_NET_RSS_HASH_TUNNEL_SRC_PORT_UDP_X?
> 
> they want an option to ignore all other header fields.

Than that looks like rss config extension on which fields of the packet to use for RSS.