Re: [PATCH bpf-next 1/5] netlink: specs: Add XDP RX checksum capability to XDP metadata specs

[Lorenzo Bianconi <lorenzo@kernel.org>]

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On Feb 12, Stanislav Fomichev wrote:
> On 02/10, 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 allow the
> > eBPF program bounded to the device to retrieve the RX checksum result
> > computed by the hw NIC.
> > 
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > ---
> >  Documentation/netlink/specs/netdev.yaml |  5 +++++
> >  include/net/xdp.h                       | 14 ++++++++++++++
> >  include/uapi/linux/netdev.h             |  3 +++
> >  net/core/xdp.c                          | 29 +++++++++++++++++++++++++++++
> >  tools/include/uapi/linux/netdev.h       |  3 +++
> >  5 files changed, 54 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..9ab9ac10ae2074b70618a9d4f32544d8b9a30b63 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 +647,22 @@ 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,
> > +	XDP_CHECKSUM_PARTIAL		= CHECKSUM_PARTIAL,
> > +};
> > +
> >  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..e51346ad3031f28d11c11f8205da6cd954da82de 100644
> > --- a/net/core/xdp.c
> > +++ b/net/core/xdp.c
> > @@ -961,6 +961,35 @@ __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``
> > + * ``XDP_CHECKSUM_PARTIAL``
> > + *
> > + * 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`` and
> > + * ``XDP_CHECKSUM_PARTIAL``.
> > + *
> > + * Return:
> > + * * Returns 0 on success or ``-errno`` on error.
> > + * * ``-EOPNOTSUPP`` : means device driver does not implement kfunc
> > + * * ``-ENODATA``    : means no RX-timestamp available for this frame
> > + */
> > +__bpf_kfunc int bpf_xdp_metadata_rx_checksum(const struct xdp_md *ctx,
> > +					     u8 *ip_summed, u32 *cksum_meta)
> > +{
> 
> Any reason not to do enum xdp_checksum *ip_summed here as well?

ack, I will fix it in v2.

Regards,
Lorenzo


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