netdev - Re: [RFC bpf-next v2 11/11] net/mlx5e: Support TX timestamp metadata

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: <4c592016-5b5e-9670-2231-b44642091d46@redhat.com>
Date: Fri, 23 Jun 2023 11:16:09 +0100
From: Maryam Tahhan <mtahhan@...hat.com>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>,
 Stanislav Fomichev <sdf@...gle.com>
Cc: 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>, Hao Luo <haoluo@...gle.com>,
 Jiri Olsa <jolsa@...nel.org>, Network Development <netdev@...r.kernel.org>,
 "Wiles, Keith" <keith.wiles@...el.com>, Jesper Brouer <jbrouer@...hat.com>
Subject: Re: [RFC bpf-next v2 11/11] net/mlx5e: Support TX timestamp metadata

On 23/06/2023 03:35, Alexei Starovoitov wrote:
> Why do you think so?
> Who are those users?
> I see your proposal and thumbs up from onlookers.
> afaict there are zero users for rx side hw hints too.
>
>> the specs are
>> not public; things can change depending on fw version/etc/etc.
>> So the progs that touch raw descriptors are not the primary use-case.
>> (that was the tl;dr for rx part, seems like it applies here?)
>>
>> Let's maybe discuss that mlx5 example? Are you proposing to do
>> something along these lines?
>>
>> void mlx5e_devtx_submit(struct mlx5e_tx_wqe *wqe);
>> void mlx5e_devtx_complete(struct mlx5_cqe64 *cqe);
>>
>> If yes, I'm missing how we define the common kfuncs in this case. The
>> kfuncs need to have some common context. We're defining them with:
>> bpf_devtx_<kfunc>(const struct devtx_frame *ctx);
> I'm looking at xdp_metadata and wondering who's using it.
> I haven't seen a single bug report.
> No bugs means no one is using it. There is zero chance that we managed
> to implement it bug-free on the first try.
> So new tx side things look like a feature creep to me.
> rx side is far from proven to be useful for anything.
> Yet you want to add new things.
>

Hi folks

We in CNDP (https://github.com/CloudNativeDataPlane/cndp) have been 
looking to use xdp_metadata to relay receive side offloads from the NIC 
to our AF_XDP applications. We see this is a key feature that is 
essential for the viability of AF_XDP in the real world. We would love 
to see something adopted for the TX side alongside what's on the RX 
side. We don't want to waste cycles do everything in software when the 
NIC HW supports many features that we need.

Thank you
Maryam