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[76.102.12.149]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-12742c6dc70sm16497835c88.8.2026.02.17.17.01.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Feb 2026 17:01:08 -0800 (PST) Date: Tue, 17 Feb 2026 17:01:07 -0800 From: Stanislav Fomichev To: Jesper Dangaard Brouer Cc: Donald Hunter , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Alexei Starovoitov , Daniel Borkmann , Lorenzo Bianconi , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , Andrew Lunn , Tony Nguyen , Przemek Kitszel , Alexander Lobakin , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , Shuah Khan , Maciej Fijalkowski , Jakub Sitnicki , netdev@vger.kernel.org, bpf@vger.kernel.org, intel-wired-lan@lists.osuosl.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH bpf-next v3 1/5] netlink: specs: Add XDP RX checksum capability to XDP metadata specs Message-ID: References: <20260217-bpf-xdp-meta-rxcksum-v3-0-30024c50ba71@kernel.org> <20260217-bpf-xdp-meta-rxcksum-v3-1-30024c50ba71@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260217-bpf-xdp-meta-rxcksum-v3-1-30024c50ba71@kernel.org> On 02/17, Lorenzo Bianconi wrote: > Introduce XDP RX checksum capability to XDP metadata specs. XDP RX > checksum will be use by devices capable of exposing receive checksum > result via bpf_xdp_metadata_rx_checksum(). > Moreover, introduce xmo_rx_checksum netdev callback in order to allow > the eBPF program bound to the device to retrieve the RX checksum result > computed by the hw NIC. > > Signed-off-by: Lorenzo Bianconi > --- > Documentation/netlink/specs/netdev.yaml | 5 +++++ > include/net/xdp.h | 13 +++++++++++++ > include/uapi/linux/netdev.h | 3 +++ > net/core/xdp.c | 28 ++++++++++++++++++++++++++++ > tools/include/uapi/linux/netdev.h | 3 +++ > 5 files changed, 52 insertions(+) > > diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml > index 596c306ce52b8303b20680ff0cd34d4fd9db0e48..58eda634668a07860447a65d9fc2284839af6244 100644 > --- a/Documentation/netlink/specs/netdev.yaml > +++ b/Documentation/netlink/specs/netdev.yaml > @@ -61,6 +61,11 @@ definitions: > doc: | > Device is capable of exposing receive packet VLAN tag via > bpf_xdp_metadata_rx_vlan_tag(). > + - > + name: checksum > + doc: | > + Device is capable of exposing receive checksum result via > + bpf_xdp_metadata_rx_checksum(). > - > type: flags > name: xsk-flags > diff --git a/include/net/xdp.h b/include/net/xdp.h > index aa742f413c358575396530879af4570dc3fc18de..00abb2e1e85514b4080d0e4e6e3b8f5f67f73b61 100644 > --- a/include/net/xdp.h > +++ b/include/net/xdp.h > @@ -586,6 +586,10 @@ void xdp_attachment_setup(struct xdp_attachment_info *info, > NETDEV_XDP_RX_METADATA_VLAN_TAG, \ > bpf_xdp_metadata_rx_vlan_tag, \ > xmo_rx_vlan_tag) \ > + XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_CHECKSUM, \ > + NETDEV_XDP_RX_METADATA_CHECKSUM, \ > + bpf_xdp_metadata_rx_checksum, \ > + xmo_rx_checksum) > > enum xdp_rx_metadata { > #define XDP_METADATA_KFUNC(name, _, __, ___) name, > @@ -643,12 +647,21 @@ enum xdp_rss_hash_type { > XDP_RSS_TYPE_L4_IPV6_SCTP_EX = XDP_RSS_TYPE_L4_IPV6_SCTP | XDP_RSS_L3_DYNHDR, > }; > > +enum xdp_checksum { > + XDP_CHECKSUM_NONE = CHECKSUM_NONE, > + XDP_CHECKSUM_UNNECESSARY = CHECKSUM_UNNECESSARY, > + XDP_CHECKSUM_COMPLETE = CHECKSUM_COMPLETE, > +}; > + > struct xdp_metadata_ops { > int (*xmo_rx_timestamp)(const struct xdp_md *ctx, u64 *timestamp); > int (*xmo_rx_hash)(const struct xdp_md *ctx, u32 *hash, > enum xdp_rss_hash_type *rss_type); > int (*xmo_rx_vlan_tag)(const struct xdp_md *ctx, __be16 *vlan_proto, > u16 *vlan_tci); > + int (*xmo_rx_checksum)(const struct xdp_md *ctx, > + enum xdp_checksum *ip_summed, > + u32 *cksum_meta); > }; > > #ifdef CONFIG_NET > diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h > index e0b579a1df4f2126acec6c44c299e97bbbefe640..d20da430cfd57bc26b5ea2f406c27b48d8a81693 100644 > --- a/include/uapi/linux/netdev.h > +++ b/include/uapi/linux/netdev.h > @@ -47,11 +47,14 @@ enum netdev_xdp_act { > * hash via bpf_xdp_metadata_rx_hash(). > * @NETDEV_XDP_RX_METADATA_VLAN_TAG: Device is capable of exposing receive > * packet VLAN tag via bpf_xdp_metadata_rx_vlan_tag(). > + * @NETDEV_XDP_RX_METADATA_CHECKSUM: Device is capable of exposing receive > + * checksum result via bpf_xdp_metadata_rx_checksum(). > */ > enum netdev_xdp_rx_metadata { > NETDEV_XDP_RX_METADATA_TIMESTAMP = 1, > NETDEV_XDP_RX_METADATA_HASH = 2, > NETDEV_XDP_RX_METADATA_VLAN_TAG = 4, > + NETDEV_XDP_RX_METADATA_CHECKSUM = 8, > }; > > /** > diff --git a/net/core/xdp.c b/net/core/xdp.c > index fee6d080ee85fc2d278bfdddfd1365633058ec06..7d1e08d8ab4151ab42c91203def2afafc66d3149 100644 > --- a/net/core/xdp.c > +++ b/net/core/xdp.c > @@ -961,6 +961,34 @@ __bpf_kfunc int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx, > return -EOPNOTSUPP; > } > > +/** > + * bpf_xdp_metadata_rx_checksum - Read XDP frame RX checksum. > + * @ctx: XDP context pointer. > + * @ip_summed: Return value pointer indicating checksum result. > + * @cksum_meta: Return value pointer indicating checksum result metadata. > + * > + * In case of success, ``ip_summed`` is set to the RX checksum result. Possible > + * values are: > + * ``XDP_CHECKSUM_NONE`` > + * ``XDP_CHECKSUM_UNNECESSARY`` > + * ``XDP_CHECKSUM_COMPLETE`` > + * > + * In case of success, ``cksum_meta`` contains the hw computed checksum value > + * for ``XDP_CHECKSUM_COMPLETE`` or the ``csum_level`` for > + * ``XDP_CHECKSUM_UNNECESSARY``. It is set to 0 for ``XDP_CHECKSUM_NONE`` The only thing I'm still not sure about is the csum_level and whether we need to export it or just start with csum_level=0 and extend later when needed. The rest looks good. Jesper, Lorenzo mentioned that you might need it? Can you clarify?