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From: "Zaremba, Larysa" <larysa.zaremba@intel.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"ast@kernel.org" <ast@kernel.org>,
	"daniel@iogearbox.net" <daniel@iogearbox.net>,
	"andrii@kernel.org" <andrii@kernel.org>,
	"martin.lau@linux.dev" <martin.lau@linux.dev>,
	"song@kernel.org" <song@kernel.org>, "yhs@fb.com" <yhs@fb.com>,
	"john.fastabend@gmail.com" <john.fastabend@gmail.com>,
	"kpsingh@kernel.org" <kpsingh@kernel.org>,
	"sdf@google.com" <sdf@google.com>,
	"haoluo@google.com" <haoluo@google.com>,
	"jolsa@kernel.org" <jolsa@kernel.org>,
	David Ahern <dsahern@gmail.com>, Jakub Kicinski <kuba@kernel.org>,
	Willem de Bruijn <willemb@google.com>,
	"Brouer, Jesper" <brouer@redhat.com>,
	"Burakov, Anatoly" <anatoly.burakov@intel.com>,
	"Lobakin, Aleksander" <aleksander.lobakin@intel.com>,
	Magnus Karlsson <magnus.karlsson@gmail.com>,
	"Tahhan, Maryam" <mtahhan@redhat.com>,
	"xdp-hints@xdp-project.net" <xdp-hints@xdp-project.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: [xdp-hints] Re: [PATCH bpf-next v3 12/21] xdp: Add checksum hint
Date: Thu, 20 Jul 2023 16:03:30 +0000	[thread overview]
Message-ID: <ZLlZ2E4rdKdBTqsf@lincoln> (raw)
In-Reply-To: <64b93cc46ad9b_2ad92129445@willemb.c.googlers.com.notmuch>

On Thu, Jul 20, 2023 at 09:55:16AM -0400, Willem de Bruijn wrote:
> Zaremba, Larysa wrote:
> > On Thu, Jul 20, 2023 at 09:57:05AM +0000, Zaremba, Larysa wrote:
> > > On Wed, Jul 19, 2023 at 05:42:04PM -0400, Willem de Bruijn wrote:
> > > > Larysa Zaremba wrote:
> > > > > Implement functionality that enables drivers to expose to XDP code checksum
> > > > > information that consists of:
> > > > > 
> > > > > - Checksum status - bitfield that consists of
> > > > >   - number of consecutive validated checksums. This is almost the same as
> > > > >     csum_level in skb, but starts with 1. Enum names for those bits still
> > > > >     use checksum level concept, so it is less confusing for driver
> > > > >     developers.
> > > > >   - Is checksum partial? This bit cannot coexist with any other
> > > > >   - Is there a complete checksum available?
> > > > > - Additional checksum data, a union of:
> > > > >   - checksum start and offset, if checksum is partial
> > > > >   - complete checksum, if available
> > > > > 
> > > > > Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
> > > > > ---
> > > > >  Documentation/networking/xdp-rx-metadata.rst |  3 ++
> > > > >  include/linux/netdevice.h                    |  3 ++
> > > > >  include/net/xdp.h                            | 46 ++++++++++++++++++++
> > > > >  kernel/bpf/offload.c                         |  2 +
> > > > >  net/core/xdp.c                               | 23 ++++++++++
> > > > >  5 files changed, 77 insertions(+)
> > > > > 
> > > > > diff --git a/Documentation/networking/xdp-rx-metadata.rst b/Documentation/networking/xdp-rx-metadata.rst
> > > > > index ea6dd79a21d3..7f056a44f682 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
> > > > > +
> > > > >  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 1749f4f75c64..4f6da36ac123 100644
> > > > > --- a/include/linux/netdevice.h
> > > > > +++ b/include/linux/netdevice.h
> > > > > @@ -1660,6 +1660,9 @@ struct xdp_metadata_ops {
> > > > >  			       enum xdp_rss_hash_type *rss_type);
> > > > >  	int	(*xmo_rx_vlan_tag)(const struct xdp_md *ctx, u16 *vlan_tci,
> > > > >  				   __be16 *vlan_proto);
> > > > > +	int	(*xmo_rx_csum)(const struct xdp_md *ctx,
> > > > > +			       enum xdp_csum_status *csum_status,
> > > > > +			       union xdp_csum_info *csum_info);
> > > > >  };
> > > > >  
> > > > >  /**
> > > > > diff --git a/include/net/xdp.h b/include/net/xdp.h
> > > > > index 89c58f56ffc6..2b7a7d678ff4 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, \
> > > > > +			   bpf_xdp_metadata_rx_csum) \
> > > > >  
> > > > >  enum {
> > > > >  #define XDP_METADATA_KFUNC(name, _) name,
> > > > > @@ -448,6 +450,50 @@ enum xdp_rss_hash_type {
> > > > >  	XDP_RSS_TYPE_L4_IPV6_SCTP_EX = XDP_RSS_TYPE_L4_IPV6_SCTP | XDP_RSS_L3_DYNHDR,
> > > > >  };
> > > > >  
> > > > > +union xdp_csum_info {
> > > > > +	/* Checksum referred to by ``csum_start + csum_offset`` is considered
> > > > > +	 * valid, but was never calculated, TX device has to do this,
> > > > > +	 * starting from csum_start packet byte.
> > > > > +	 * Any preceding checksums are also considered valid.
> > > > > +	 * Available, if ``status == XDP_CHECKSUM_PARTIAL``.
> > > > > +	 */
> > > > > +	struct {
> > > > > +		u16 csum_start;
> > > > > +		u16 csum_offset;
> > > > > +	};
> > > > > +
> > > > > +	/* Checksum, calculated over the whole packet.
> > > > > +	 * Available, if ``status & XDP_CHECKSUM_COMPLETE``.
> > > > > +	 */
> > > > > +	u32 checksum;
> > > > > +};
> > > > > +
> > > > > +enum xdp_csum_status {
> > > > > +	/* HW had parsed several transport headers and validated their
> > > > > +	 * checksums, same as ``CHECKSUM_UNNECESSARY`` in ``sk_buff``.
> > > > > +	 * 3 least significat bytes contain number of consecutive checksum,
> > > > 
> > > > typo: significant
> > > > 
> > > > (I did not scan for typos, just came across this when trying to understand
> > > > the skb->csum_level + 1 trick. Probably good to run a spell check).
> > > >
> > 
> > Oh, and about skb->csum_level + 1, maybe this way it would be more 
> > understandable: XDP_CHECKSUM_VALID_LVL0 + skb->csum_level?
> 
> Agreed, that would help document the intent.
>  
> > Using number of valid checksums (starts with 1) instead of checksum level 
> > (starts with 0) is a debatable decision, but I have decided to go with it under 
> > 2 assumptions:
> > 
> > - the only reason checksum level in skb starts with 0 is to use less bits
> > - checksum number would be more intuitive for XDP/AF_XDP application developers
> > 
> > I encourage everyone to share their opinion on that.
> 
> I assumed this offset by one was because csum_status zero implicitly
> meant XDP_CHECKSUM_NONE. Is that not correct? That should probably
> get an explicit name.
> 

Well, I was not sure, whether I should add XDP_CHECKSUM_NONE, because it would 
be equal to returning -ENODATA from kfunc, but after giving it some thought now, 
it is worth to have XDP_CHECKSUM_NONE for packets that have no checksum to 
check, like for hash there is XDP_RSS_TYPE_L2.

  reply	other threads:[~2023-07-20 16:04 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-19 18:37 [xdp-hints] [PATCH bpf-next v3 00/21] XDP metadata via kfuncs for ice Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 01/21] ice: make RX hash reading code more reusable Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 02/21] ice: make RX HW timestamp " Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 03/21] ice: make RX checksum checking " Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 04/21] ice: Make ptype internal to descriptor info processing Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 05/21] ice: Introduce ice_xdp_buff Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 06/21] ice: Support HW timestamp hint Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 07/21] ice: Support RX hash XDP hint Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 08/21] ice: Support XDP hints in AF_XDP ZC mode Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 09/21] xdp: Add VLAN tag hint Larysa Zaremba
2023-07-20 21:49   ` [xdp-hints] " Stanislav Fomichev
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 10/21] ice: Implement " Larysa Zaremba
2023-07-20 18:50   ` [xdp-hints] " Simon Horman
2023-07-21  7:38     ` Zaremba, Larysa
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 11/21] ice: use VLAN proto from ring packet context in skb path Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 12/21] xdp: Add checksum hint Larysa Zaremba
2023-07-19 21:42   ` [xdp-hints] " Willem de Bruijn
2023-07-20  9:57     ` Zaremba, Larysa
2023-07-20 10:10       ` Zaremba, Larysa
2023-07-20 13:55         ` Willem de Bruijn
2023-07-20 16:03           ` Zaremba, Larysa [this message]
2023-07-20 22:27             ` Willem de Bruijn
2023-07-21  8:01               ` Zaremba, Larysa
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 13/21] ice: Implement " Larysa Zaremba
2023-07-19 18:59   ` [xdp-hints] " Alexei Starovoitov
2023-07-19 21:51     ` Willem de Bruijn
2023-07-20  9:47       ` Zaremba, Larysa
2023-07-20 15:14         ` Alexei Starovoitov
2023-07-20 15:41           ` Zaremba, Larysa
2023-07-20 21:58             ` Stanislav Fomichev
2023-07-20 22:24               ` Willem de Bruijn
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 14/21] selftests/bpf: Allow VLAN packets in xdp_hw_metadata Larysa Zaremba
2023-07-20 21:58   ` [xdp-hints] " Stanislav Fomichev
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 15/21] net, xdp: allow metadata > 32 Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 16/21] selftests/bpf: Add flags and new hints to xdp_hw_metadata Larysa Zaremba
2023-07-20 22:00   ` [xdp-hints] " Stanislav Fomichev
2023-07-21  7:41     ` Zaremba, Larysa
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 17/21] veth: Implement VLAN tag and checksum XDP hint Larysa Zaremba
2023-07-20 22:02   ` [xdp-hints] " Stanislav Fomichev
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 18/21] net: make vlan_get_tag() return -ENODATA instead of -EINVAL Larysa Zaremba
2023-07-20 22:02   ` [xdp-hints] " Stanislav Fomichev
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 19/21] selftests/bpf: Use AF_INET for TX in xdp_metadata Larysa Zaremba
2023-07-20 22:05   ` [xdp-hints] " Stanislav Fomichev
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 20/21] selftests/bpf: Check VLAN tag and proto " Larysa Zaremba
2023-07-20 22:14   ` [xdp-hints] " Stanislav Fomichev
2023-07-21  7:46     ` Zaremba, Larysa
2023-07-21 16:44       ` Stanislav Fomichev
2023-07-25  7:11         ` Larysa Zaremba
2023-07-19 18:37 ` [xdp-hints] [PATCH bpf-next v3 21/21] selftests/bpf: check checksum state " Larysa Zaremba
2023-07-20 22:14   ` [xdp-hints] " Stanislav Fomichev

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