From: Jakub Kicinski <kuba@kernel.org>
To: "Song, Yoong Siang" <yoong.siang.song@intel.com>
Cc: "Stanislav Fomichev" <stfomichev@gmail.com>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Paolo Abeni" <pabeni@redhat.com>,
"Simon Horman" <horms@kernel.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Alexei Starovoitov" <ast@kernel.org>,
"John Fastabend" <john.fastabend@gmail.com>,
"Stanislav Fomichev" <sdf@fomichev.me>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <martin.lau@linux.dev>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Song Liu" <song@kernel.org>,
"Yonghong Song" <yonghong.song@linux.dev>,
"KP Singh" <kpsingh@kernel.org>, "Hao Luo" <haoluo@google.com>,
"Jiri Olsa" <jolsa@kernel.org>, "Mykola Lysenko" <mykolal@fb.com>,
"Shuah Khan" <shuah@kernel.org>,
"Magnus Karlsson" <magnus.karlsson@gmail.com>,
"Björn Töpel" <bjorn@kernel.org>,
"Fijalkowski, Maciej" <maciej.fijalkowski@intel.com>,
"Jonathan Lemon" <jonathan.lemon@gmail.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH bpf-next,v3 2/2] selftests/bpf: Enhance XDP Rx metadata handling
Date: Thu, 10 Jul 2025 10:28:25 -0700 [thread overview]
Message-ID: <20250710102825.744f2653@kernel.org> (raw)
In-Reply-To: <IA3PR11MB92540CF6DB5BCFD34384A280D848A@IA3PR11MB9254.namprd11.prod.outlook.com>
On Thu, 10 Jul 2025 15:35:32 +0000 Song, Yoong Siang wrote:
> Would it be advisable to update the documentation to indicate that
> drivers are expected to copy any device-reserved metadata from the
> metadata area? This would ensure that xdp_buff->data_meta is equal
> to xdp_buff->data before a BPF program is executed. This approach
> would allow BPF programs to freely manipulate the metadata area
> in XDP_REDIRECT scenarios.
Documenting sounds good.
> Additionally, I am uncertain about the need to overriding metadata in
> XDP_PASS scenarios. Should BPF programs refrain from overriding the
> metadata in this case?
IIRC XDP_PASS was the initial use case for the metadata area.
The driver needs to evacuate any HW metadata before handing over
to the XDP program.
next prev parent reply other threads:[~2025-07-10 17:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-02 16:57 [PATCH bpf-next,v3 0/2] Clarify and Enhance XDP Rx Metadata Handling Song Yoong Siang
2025-07-02 16:57 ` [PATCH bpf-next,v3 1/2] doc: enhance explanation of XDP Rx metadata layout and METADATA_SIZE Song Yoong Siang
2025-07-03 15:57 ` Daniel Borkmann
2025-07-04 0:33 ` Song, Yoong Siang
2025-07-02 16:57 ` [PATCH bpf-next,v3 2/2] selftests/bpf: Enhance XDP Rx metadata handling Song Yoong Siang
2025-07-03 17:04 ` Jesper Dangaard Brouer
2025-07-04 1:17 ` Song, Yoong Siang
2025-07-04 9:58 ` Jesper Dangaard Brouer
2025-07-04 11:38 ` Daniel Borkmann
2025-07-07 15:03 ` Stanislav Fomichev
2025-07-09 14:00 ` Daniel Borkmann
2025-07-09 16:29 ` Stanislav Fomichev
2025-07-10 15:35 ` Song, Yoong Siang
2025-07-10 17:28 ` Jakub Kicinski [this message]
2025-07-03 15:41 ` [PATCH bpf-next,v3 0/2] Clarify and Enhance XDP Rx Metadata Handling Stanislav Fomichev
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