netdev - Re: XDP seeking input from NIC hardware vendors

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Date:	Fri, 8 Jul 2016 14:44:53 +0100
From:	Jakub Kicinski <jakub.kicinski@...ronome.com>
To:	Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:	"Fastabend, John R" <john.r.fastabend@...el.com>,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	"iovisor-dev@...ts.iovisor.org" <iovisor-dev@...ts.iovisor.org>,
	Brenden Blanco <bblanco@...mgrid.com>,
	Rana Shahout <ranas@...lanox.com>, Ari Saha <as754m@....com>,
	Tariq Toukan <tariqt@...lanox.com>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Simon Horman <horms@...ge.net.au>,
	Simon Horman <simon.horman@...ronome.com>,
	Edward Cree <ecree@...arflare.com>
Subject: Re: XDP seeking input from NIC hardware vendors

On Thu, 7 Jul 2016 19:22:12 -0700, Alexei Starovoitov wrote:
> > If the goal is to just separate XDP traffic from non-XDP traffic you could accomplish this with a combination of SR-IOV/macvlan to separate the device queues into multiple netdevs and then run XDP on just one of the netdevs. Then use flow director (ethtool) or 'tc cls_u32/flower' to steer traffic to the netdev. This is how we support multiple networking stacks on one device by the way it is called the bifurcated driver. Its not too far of a stretch to think we could offload some simple XDP programs to program the splitting of traffic instead of cls_u32/flower/flow_director and then you would have a stack of XDP programs. One running in hardware and a set running on the queues in software.  
> 
> the above sounds like much better approach then Jesper/mine prog_per_ring stuff.
> If we can split the nic via sriov and have dedicated netdev via VF just for XDP that's way cleaner approach.
> I guess we won't need to do xdp_rxqmask after all.

+1

I was thinking about using eBPF to direct to NIC queues but concluded
that doing a redirect to a VF is cleaner.  Especially if the PF driver
supports VF representatives we could potentially just use
bpf_redirect(VFR netdev) and the VF doesn't even have to be handled by
the same stack.