netdev - Re: [PATCH bpf-next v4 12/21] xdp: Add checksum hint

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZNEHuaY+9LWzfZMt@lincoln>
Date: Mon, 7 Aug 2023 17:03:21 +0200
From: Larysa Zaremba <larysa.zaremba@...el.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
CC: Alexei Starovoitov <alexei.starovoitov@...il.com>, bpf
	<bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
	<daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau
	<martin.lau@...ux.dev>, Song Liu <song@...nel.org>, Yonghong Song
	<yhs@...com>, John Fastabend <john.fastabend@...il.com>, KP Singh
	<kpsingh@...nel.org>, Stanislav Fomichev <sdf@...gle.com>, Hao Luo
	<haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, David Ahern
	<dsahern@...il.com>, Jakub Kicinski <kuba@...nel.org>, Willem de Bruijn
	<willemb@...gle.com>, Jesper Dangaard Brouer <brouer@...hat.com>, "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>, "Network
 Development" <netdev@...r.kernel.org>, Simon Horman
	<simon.horman@...igine.com>
Subject: Re: [PATCH bpf-next v4 12/21] xdp: Add checksum hint

On Wed, Aug 02, 2023 at 09:27:27AM -0400, Willem de Bruijn wrote:
> > No. What I'm saying is that XDP_CHECKSUM_UNNECESSARY should be
> > equivalent to skb's CHECKSUM_UNNECESSARY with csum_level = 0.
> > I'm well aware that some drivers are trying to be smart and put csum_level=1.
> > There is no use case for it in XDP.
> > "But our HW supports it so XDP prog should read it" is the reason NOT
> > to expose it to bpf in generic api.
> > 
> > Either we're doing per-driver kfuncs and no common infra or common kfunc
> > that covers 99% of the drivers. Which is CHECKSUM_UNNECESSARY && csum_level = 0
> > 
> > It's not acceptable to present a generic api to xdp prog with multi level
> > csum that only works on a specific HW. Next thing there will be new flags
> > and MAX_CSUM_LEVEL in XDP features.
> > Pretending to be generic while being HW specific is the worst interface.
> 
> Ok. Agreed that without it we still cover 99% of the use cases. Fine to drop.

Sorry for the late response.
Thanks everyone for the feedback, will drop the checksum level concept from the 
design.