Re: [PATCH RESEND bpf-next 11/15] xdp: Add checksum level hint

Larysa Zaremba
2023-05-15T13:52:17Z

On Fri, May 12, 2023 at 11:34:21AM -0700, Stanislav Fomichev wrote:
> On 05/12, Larysa Zaremba wrote:
> > Implement functionality that enables drivers to expose to XDP code,
> > whether checksums was checked and on what level.
> >
> > Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
> > ---
> > Documentation/networking/xdp-rx-metadata.rst | 3 +++
> > include/linux/netdevice.h | 1 +
> > include/net/xdp.h | 2 ++
> > kernel/bpf/offload.c | 2 ++
> > net/core/xdp.c | 12 ++++++++++++
> > 5 files changed, 20 insertions(+)
> >
> > diff --git a/Documentation/networking/xdp-rx-metadata.rst b/Documentation/networking/xdp-rx-metadata.rst
> > index 73a78029c596..f74f0e283097 100644
> > --- a/Documentation/networking/xdp-rx-metadata.rst
> > +++ b/Documentation/networking/xdp-rx-metadata.rst
> > @@ -29,6 +29,9 @@ metadata is supported, this set will grow:
> > .. kernel-doc:: net/core/xdp.c
> > :identifiers: bpf_xdp_metadata_rx_stag
> >
> > +.. kernel-doc:: net/core/xdp.c
> > + :identifiers: bpf_xdp_metadata_rx_csum_lvl
> > +
> > An XDP program can use these kfuncs to read the metadata into stack
> > variables for its own consumption. Or, to pass the metadata on to other
> > consumers, an XDP program can store it into the metadata area carried
> > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > index fdae37fe11f5..ddade3a15366 100644
> > --- a/include/linux/netdevice.h
> > +++ b/include/linux/netdevice.h
> > @@ -1657,6 +1657,7 @@ struct xdp_metadata_ops {
> > enum xdp_rss_hash_type *rss_type);
> > int (*xmo_rx_ctag)(const struct xdp_md *ctx, u16 *vlan_tag);
> > int (*xmo_rx_stag)(const struct xdp_md *ctx, u16 *vlan_tag);
> > + int (*xmo_rx_csum_lvl)(const struct xdp_md *ctx, u8 *csum_level);
> > };
> >
> > /**
> > diff --git a/include/net/xdp.h b/include/net/xdp.h
> > index 2db7439fc60f..0fbd25616241 100644
> > --- a/include/net/xdp.h
> > +++ b/include/net/xdp.h
> > @@ -393,6 +393,8 @@ void xdp_attachment_setup(struct xdp_attachment_info *info,
> > bpf_xdp_metadata_rx_ctag) \
> > XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_STAG, \
> > bpf_xdp_metadata_rx_stag) \
> > + XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_CSUM_LVL, \
> > + bpf_xdp_metadata_rx_csum_lvl) \
> >
> > enum {
> > #define XDP_METADATA_KFUNC(name, _) name,
> > diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
> > index 2c6b6e82cfac..8bd54fb4ac63 100644
> > --- a/kernel/bpf/offload.c
> > +++ b/kernel/bpf/offload.c
> > @@ -852,6 +852,8 @@ void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id)
> > p = ops->xmo_rx_ctag;
> > else if (func_id == bpf_xdp_metadata_kfunc_id(XDP_METADATA_KFUNC_RX_STAG))
> > p = ops->xmo_rx_stag;
> > + else if (func_id == bpf_xdp_metadata_kfunc_id(XDP_METADATA_KFUNC_RX_CSUM_LVL))
> > + p = ops->xmo_rx_csum_lvl;
> > out:
> > up_read(&bpf_devs_lock);
> >
> > diff --git a/net/core/xdp.c b/net/core/xdp.c
> > index eff21501609f..7dd45fd62983 100644
> > --- a/net/core/xdp.c
> > +++ b/net/core/xdp.c
> > @@ -762,6 +762,18 @@ __bpf_kfunc int bpf_xdp_metadata_rx_stag(const struct xdp_md *ctx, u16 *vlan_tag
> > return -EOPNOTSUPP;
> > }
> >
> > +/**
> > + * bpf_xdp_metadata_rx_csum_lvl - Get depth at which HW has checked the checksum.
> > + * @ctx: XDP context pointer.
> > + * @csum_level: Return value pointer.
>
> Let's maybe clarify what the level means here? For example, do we start
> counting from 0 or 1?

Sure, I'll add a comment that the meaning of level is the same as in skb,
counting from 0.

>
> > + *
> > + * Returns 0 on success (HW has checked the checksum) or ``-errno`` on error.
> > + */
> > +__bpf_kfunc int bpf_xdp_metadata_rx_csum_lvl(const struct xdp_md *ctx, u8 *csum_level)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > +
> > __diag_pop();
> >
> > BTF_SET8_START(xdp_metadata_kfunc_ids)
> > --
> > 2.35.3
> >