Re: [virtio-dev] Re: [virtio-comment] Re: [PATCH v7] virtio-net: support inner header hash

[Heng Qi <hengqi@linux.alibaba.com>]

å 2023/2/8 äå1:18, Parav Pandit åé:
> > From: Heng Qi <hengqi@linux.alibaba.com>
> > Sent: Tuesday, February 7, 2023 10:25 PM
> [..]
> > > > Do you think we need both hash_types and hash_tunnel_types?
> > > In struct virtio_net_config we need two fields.
> > > a. supported_hash_types (already exists) b. supported_hash_tunnel_type
> > > -> bitmap indicating for which outer headers, inner hash calculation is
> > supported.
> >
> > Thanks for the suggestion, we seem to have reached an agreement.
> >
> > > In struct virtio_net_hdr we need two fields.
> > > a. hash_report (already exists)
> > > b. hash_tunnel_type 8 bits -> absolute value indicating which outer header
> > exists when inner header hash calculated.
> > > You already have it in your patch named as hash_report_tunnel.
> > > May be better to name as hash_report_tunnel_type to make it clearer that its
> > type.
> >
> > Sure.
> >
> > Thanks for your reply.
> I had one last question. Why do we need to inform the hash_report_tunnel_type of the outer header in the virtio_net_hdr?
> Is this for debug? Or is there a use case that will process this value?

The driver may use it to do some statistical information, or do some rx 
classification
based on the rx hash, and we'd better not hide information from the driver.

Thanks.