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From: Larysa Zaremba <larysa.zaremba@intel.com>
To: Jesper Dangaard Brouer <jbrouer@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>,
	brouer@redhat.com, bpf@vger.kernel.org, ast@kernel.org,
	daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev,
	song@kernel.org, yhs@fb.com, kpsingh@kernel.org, sdf@google.com,
	haoluo@google.com, jolsa@kernel.org,
	David Ahern <dsahern@gmail.com>, Jakub Kicinski <kuba@kernel.org>,
	Willem de Bruijn <willemb@google.com>,
	Anatoly Burakov <anatoly.burakov@intel.com>,
	Alexander Lobakin <alexandr.lobakin@intel.com>,
	Magnus Karlsson <magnus.karlsson@gmail.com>,
	Maryam Tahhan <mtahhan@redhat.com>,
	xdp-hints@xdp-project.net, netdev@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	Alexander Duyck <alexander.duyck@gmail.com>
Subject: [xdp-hints] Re: [PATCH bpf-next v2 12/20] xdp: Add checksum level hint
Date: Tue, 4 Jul 2023 13:19:24 +0200	[thread overview]
Message-ID: <ZKQAPBcIE/iCkiX2@lincoln> (raw)
In-Reply-To: <9cd44759-416c-7274-f805-ee9d756f15b1@redhat.com>

On Tue, Jul 04, 2023 at 12:39:06PM +0200, Jesper Dangaard Brouer wrote:
> Cc. DaveM+Alex Duyck, as I value your insights on checksums.
> 
> On 04/07/2023 11.24, Larysa Zaremba wrote:
> > On Mon, Jul 03, 2023 at 01:38:27PM -0700, John Fastabend wrote:
> > > 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                               | 21 ++++++++++++++++++++
> > > >   5 files changed, 29 insertions(+)
> > > > 
> > > > diff --git a/Documentation/networking/xdp-rx-metadata.rst b/Documentation/networking/xdp-rx-metadata.rst
> > > > index ea6dd79a21d3..4ec6ddfd2a52 100644
> > > > --- a/Documentation/networking/xdp-rx-metadata.rst
> > > > +++ b/Documentation/networking/xdp-rx-metadata.rst
> > > > @@ -26,6 +26,9 @@ metadata is supported, this set will grow:
> > > >   .. kernel-doc:: net/core/xdp.c
> > > >      :identifiers: bpf_xdp_metadata_rx_vlan_tag
> > > > +.. 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 4fa4380e6d89..569563687172 100644
> > > > --- a/include/linux/netdevice.h
> > > > +++ b/include/linux/netdevice.h
> > > > @@ -1660,6 +1660,7 @@ struct xdp_metadata_ops {
> > > >   			       enum xdp_rss_hash_type *rss_type);
> > > >   	int	(*xmo_rx_vlan_tag)(const struct xdp_md *ctx, u16 *vlan_tag,
> > > >   				   __be16 *vlan_proto);
> > > > +	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 89c58f56ffc6..61ed38fa79d1 100644
> > > > --- a/include/net/xdp.h
> > > > +++ b/include/net/xdp.h
> > > > @@ -391,6 +391,8 @@ void xdp_attachment_setup(struct xdp_attachment_info *info,
> > > >   			   bpf_xdp_metadata_rx_hash) \
> > > >   	XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_VLAN_TAG, \
> > > >   			   bpf_xdp_metadata_rx_vlan_tag) \
> > > > +	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 986e7becfd42..a133fb775f49 100644
> > > > --- a/kernel/bpf/offload.c
> > > > +++ b/kernel/bpf/offload.c
> > > > @@ -850,6 +850,8 @@ void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id)
> > > >   		p = ops->xmo_rx_hash;
> > > >   	else if (func_id == bpf_xdp_metadata_kfunc_id(XDP_METADATA_KFUNC_RX_VLAN_TAG))
> > > >   		p = ops->xmo_rx_vlan_tag;
> > > > +	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 f6262c90e45f..c666d3e0a26c 100644
> > > > --- a/net/core/xdp.c
> > > > +++ b/net/core/xdp.c
> > > > @@ -758,6 +758,27 @@ __bpf_kfunc int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx, u16 *vlan
> > > >   	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.
> > > > + *
> > > > + * In case of success, csum_level contains depth of the last verified checksum.
> > > > + * If only the outermost checksum was verified, csum_level is 0, if both
> > > > + * encapsulation and inner transport checksums were verified, csum_level is 1,
> > > > + * and so on.
> > > > + * For more details, refer to csum_level field in sk_buff.
> > > > + *
> > > > + * Return:
> > > > + * * Returns 0 on success or ``-errno`` on error.
> > > > + * * ``-EOPNOTSUPP`` : device driver doesn't implement kfunc
> > > > + * * ``-ENODATA``    : Checksum was not validated
> > > > + */
> > > > +__bpf_kfunc int bpf_xdp_metadata_rx_csum_lvl(const struct xdp_md *ctx, u8 *csum_level)
> > > 
> > > Istead of ENODATA should we return what would be put in the ip_summed field
> > > CHECKSUM_{NONE, UNNECESSARY, COMPLETE, PARTIAL}? Then sig would be,
> 
> I was thinking the same, what about checksum "type".
> 
> > > 
> > >   bpf_xdp_metadata_rx_csum_lvl(const struct xdp_md *ctx, u8 *type, u8 *lvl);
> > > 
> > > or something like that? Or is the thought that its not really necessary?
> > > I don't have a strong preference but figured it was worth asking.
> > > 
> > 
> > I see no value in returning CHECKSUM_COMPLETE without the actual checksum value.
> > Same with CHECKSUM_PARTIAL and csum_start. Returning those values too would
> > overcomplicate the function signature.
> 
> So, this kfunc bpf_xdp_metadata_rx_csum_lvl() success is it equivilent to
> CHECKSUM_UNNECESSARY?

This is 100% true for physical NICs, it's more complicated for veth, bacause it 
often receives CHECKSUM_PARTIAL, which shouldn't normally apprear on RX, but is 
treated by the network stack as a validated checksum, because there is no way 
internally generated packet could be messed up. I would be grateful if you could 
look at the veth patch and share your opinion about this.

> 
> Looking at documentation[1] (generated from skbuff.h):
>  [1] https://kernel.org/doc/html/latest/networking/skbuff.html#checksumming-of-received-packets-by-device
> 
> Is the idea that we can add another kfunc (new signature) than can deal
> with the other types of checksums (in a later kernel release)?
>

Yes, that is the idea.
 
> 
> > > > +{
> > > > +	return -EOPNOTSUPP;
> > > > +}
> > > > +
> > > >   __diag_pop();
> > 
> 

  reply	other threads:[~2023-07-04 11:23 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-03 18:12 [xdp-hints] [PATCH bpf-next v2 00/20] XDP metadata via kfuncs for ice Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 01/20] ice: make RX hash reading code more reusable Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 02/20] ice: make RX HW timestamp " Larysa Zaremba
2023-07-04 10:04   ` [xdp-hints] " Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 03/20] ice: make RX checksum checking " Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 04/20] ice: Make ptype internal to descriptor info processing Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 05/20] ice: Introduce ice_xdp_buff Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 06/20] ice: Support HW timestamp hint Larysa Zaremba
2023-07-05 17:30   ` [xdp-hints] " Stanislav Fomichev
2023-07-06 14:22     ` Larysa Zaremba
2023-07-06 16:39       ` Stanislav Fomichev
2023-07-10 15:49         ` Larysa Zaremba
2023-07-10 18:12           ` Stanislav Fomichev
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 07/20] ice: Support RX hash XDP hint Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 08/20] ice: Support XDP hints in AF_XDP ZC mode Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 09/20] xdp: Add VLAN tag hint Larysa Zaremba
2023-07-03 20:15   ` [xdp-hints] " John Fastabend
2023-07-04  8:23     ` Larysa Zaremba
2023-07-04 10:23       ` Jesper Dangaard Brouer
2023-07-04 11:02         ` Larysa Zaremba
2023-07-04 14:18           ` Jesper Dangaard Brouer
2023-07-06 14:46             ` Larysa Zaremba
2023-07-07 13:57               ` Jesper Dangaard Brouer
2023-07-07 17:58                 ` Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 10/20] ice: Implement " Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 11/20] ice: use VLAN proto from ring packet context in skb path Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 12/20] xdp: Add checksum level hint Larysa Zaremba
2023-07-03 20:38   ` [xdp-hints] " John Fastabend
2023-07-04  9:24     ` Larysa Zaremba
2023-07-04 10:39       ` Jesper Dangaard Brouer
2023-07-04 11:19         ` Larysa Zaremba [this message]
2023-07-06  5:50           ` John Fastabend
2023-07-06  9:04             ` Jesper Dangaard Brouer
2023-07-06 12:38               ` Larysa Zaremba
2023-07-06 12:49                 ` Larysa Zaremba
2023-07-10 16:58                   ` Alexander Lobakin
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 13/20] ice: Implement " Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 14/20] selftests/bpf: Allow VLAN packets in xdp_hw_metadata Larysa Zaremba
2023-07-05 17:31   ` [xdp-hints] " Stanislav Fomichev
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 15/20] net, xdp: allow metadata > 32 Larysa Zaremba
2023-07-03 21:06   ` [xdp-hints] " John Fastabend
2023-07-06 14:51     ` Larysa Zaremba
2023-07-10 14:01       ` Alexander Lobakin
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 16/20] selftests/bpf: Add flags and new hints to xdp_hw_metadata Larysa Zaremba
2023-07-04 11:03   ` [xdp-hints] " Jesper Dangaard Brouer
2023-07-04 11:04     ` Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 17/20] veth: Implement VLAN tag and checksum level XDP hint Larysa Zaremba
2023-07-05 17:25   ` [xdp-hints] " Stanislav Fomichev
2023-07-06  9:57     ` Jesper Dangaard Brouer
2023-07-06 10:15       ` Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 18/20] selftests/bpf: Use AF_INET for TX in xdp_metadata Larysa Zaremba
2023-07-05 17:39   ` [xdp-hints] " Stanislav Fomichev
2023-07-06 14:11     ` Larysa Zaremba
2023-07-06 17:25       ` Stanislav Fomichev
2023-07-06 17:27       ` Stanislav Fomichev
2023-07-07  8:33         ` Larysa Zaremba
2023-07-07 16:49           ` Stanislav Fomichev
2023-07-07 16:58             ` Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 19/20] selftests/bpf: Check VLAN tag and proto " Larysa Zaremba
2023-07-05 17:41   ` [xdp-hints] " Stanislav Fomichev
2023-07-06 10:10   ` Jesper Dangaard Brouer
2023-07-06 10:13     ` Larysa Zaremba
2023-07-03 18:12 ` [xdp-hints] [PATCH bpf-next v2 20/20] selftests/bpf: check checksum level " Larysa Zaremba
2023-07-05 17:41   ` [xdp-hints] " Stanislav Fomichev
2023-07-06 10:25   ` Jesper Dangaard Brouer
2023-07-06 12:02     ` Larysa Zaremba

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