netdev - Re: [xdp-hints] Re: [PATCH bpf-next v7 17/18] selftests/bpf: Use AF_INET for TX in xdp

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Message-ID: <ZVxyDhqz4mBZwIpl@lzaremba-mobl.ger.corp.intel.com>
Date: Tue, 21 Nov 2023 10:02:06 +0100
From: Larysa Zaremba <larysa.zaremba@...el.com>
To: Stanislav Fomichev <sdf@...gle.com>
CC: <bpf@...r.kernel.org>, <ast@...nel.org>, <daniel@...earbox.net>,
	<andrii@...nel.org>, <martin.lau@...ux.dev>, <song@...nel.org>, <yhs@...com>,
	<john.fastabend@...il.com>, <kpsingh@...nel.org>, <haoluo@...gle.com>,
	<jolsa@...nel.org>, David Ahern <dsahern@...il.com>, Jakub Kicinski
	<kuba@...nel.org>, Willem de Bruijn <willemb@...gle.com>, "Jesper Dangaard
 Brouer" <hawk@...nel.org>, Anatoly Burakov <anatoly.burakov@...el.com>,
	Alexander Lobakin <alexandr.lobakin@...el.com>, Magnus Karlsson
	<magnus.karlsson@...il.com>, Maryam Tahhan <mtahhan@...hat.com>,
	<xdp-hints@...-project.net>, <netdev@...r.kernel.org>, Willem de Bruijn
	<willemdebruijn.kernel@...il.com>, Alexei Starovoitov
	<alexei.starovoitov@...il.com>, Tariq Toukan <tariqt@...lanox.com>, "Saeed
 Mahameed" <saeedm@...lanox.com>, Maciej Fijalkowski
	<maciej.fijalkowski@...el.com>
Subject: Re: [xdp-hints] Re: [PATCH bpf-next v7 17/18] selftests/bpf: Use
 AF_INET for TX in xdp_metadata

On Mon, Nov 20, 2023 at 01:15:41PM -0800, Stanislav Fomichev via xdp-hints wrote:
> Date: Mon, 20 Nov 2023 13:15:41 -0800
> From: Stanislav Fomichev <sdf@...gle.com>
> To: Larysa Zaremba <larysa.zaremba@...el.com>
> CC: bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
>  andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org, yhs@...com,
>  john.fastabend@...il.com, kpsingh@...nel.org, haoluo@...gle.com,
>  jolsa@...nel.org, David Ahern <dsahern@...il.com>, Jakub Kicinski
>  <kuba@...nel.org>, Willem de Bruijn <willemb@...gle.com>, Jesper Dangaard
>  Brouer <hawk@...nel.org>, Anatoly Burakov <anatoly.burakov@...el.com>,
>  Alexander Lobakin <alexandr.lobakin@...el.com>, Magnus Karlsson
>  <magnus.karlsson@...il.com>, Maryam Tahhan <mtahhan@...hat.com>,
>  xdp-hints@...-project.net, netdev@...r.kernel.org, Willem de Bruijn
>  <willemdebruijn.kernel@...il.com>, Alexei Starovoitov
>  <alexei.starovoitov@...il.com>, Tariq Toukan <tariqt@...lanox.com>, Saeed
>  Mahameed <saeedm@...lanox.com>, Maciej Fijalkowski
>  <maciej.fijalkowski@...el.com>
> Subject: [xdp-hints] Re: [PATCH bpf-next v7 17/18] selftests/bpf: Use
>  AF_INET for TX in xdp_metadata
> 
> On 11/15, Larysa Zaremba wrote:
> > The easiest way to simulate stripped VLAN tag in veth is to send a packet
> > from VLAN interface, attached to veth. Unfortunately, this approach is
> > incompatible with AF_XDP on TX side, because VLAN interfaces do not have
> > such feature.
> > 
> > Replace AF_XDP packet generation with sending the same datagram via
> > AF_INET socket.
> > 
> > This does not change the packet contents or hints values with one notable
> > exception: rx_hash_type, which previously was expected to be 0, now is
> > expected be at least XDP_RSS_TYPE_L4.
> 
> Btw, I've been thinking a bit about how we can make this test work for both
> your VLANs and my upcoming af_xdp tx side. And seems like the best
> way, probably, is to have two tx paths exercised: veth and af_xdp.
> For veth, we'll verify everything+vlans, for af_xdp we'll verify
> everything except the vlans.
> 
> Originally I was assuming that I'll switch this part back to af_xdp, but
> I don't think having tx vlan offload makes sense (because af_xdp
> userspace can just prepare the correct header from the start).
> 
> So if you're doing a respin, maybe see if we can keep af_xdp tx part
> but make it skip the vlans verification?
> 
> generate_packet_af_xdp();
> verify_xsk_metadata(/*verify_vlans=*/false);
> geenrate_packet_veth();
> verify_xsk_metadata(/*verify_vlans=*/true);
> 
> ?

Sounds good to me, will do so.