Re: [PATCH bpf-next v3 13/21] ice: Implement checksum hint

From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	 Larysa Zaremba <larysa.zaremba@intel.com>
Cc: bpf@vger.kernel.org,  ast@kernel.org,  daniel@iogearbox.net,
	 andrii@kernel.org,  martin.lau@linux.dev,  song@kernel.org,
	 yhs@fb.com,  john.fastabend@gmail.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>,
	 Jesper Dangaard Brouer <brouer@redhat.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
Subject: Re: [PATCH bpf-next v3 13/21] ice: Implement checksum hint
Date: Wed, 19 Jul 2023 17:51:17 -0400	[thread overview]
Message-ID: <64b85ad52d012_2849c1294df@willemb.c.googlers.com.notmuch> (raw)
In-Reply-To: <20230719185930.6adapqctxfdsfmye@macbook-pro-8.dhcp.thefacebook.com>

Alexei Starovoitov wrote:
> On Wed, Jul 19, 2023 at 08:37:26PM +0200, Larysa Zaremba wrote:
> > Implement .xmo_rx_csum callback to allow XDP code to determine,
> > whether HW has validated any checksums.
> > 
> > Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
> > ---
> >  drivers/net/ethernet/intel/ice/ice_txrx_lib.c | 29 +++++++++++++++++++
> >  1 file changed, 29 insertions(+)
> > 
> > diff --git a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> > index 54685d0747aa..6647a7e55ac8 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> > +++ b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> > @@ -660,8 +660,37 @@ static int ice_xdp_rx_vlan_tag(const struct xdp_md *ctx, u16 *vlan_tci,
> >  	return 0;
> >  }
> >  
> > +/**
> > + * ice_xdp_rx_csum_lvl - Get level, at which HW has checked the checksum
> > + * @ctx: XDP buff pointer
> > + * @csum_status: destination address
> > + * @csum_info: destination address
> > + *
> > + * Copy HW checksum level (if was checked) to the destination address.
> > + */
> > +static int ice_xdp_rx_csum(const struct xdp_md *ctx,
> > +			   enum xdp_csum_status *csum_status,
> > +			   union xdp_csum_info *csum_info)
> > +{
> > +	const struct ice_xdp_buff *xdp_ext = (void *)ctx;
> > +	const union ice_32b_rx_flex_desc *eop_desc;
> > +	enum ice_rx_csum_status status;
> > +	u16 ptype;
> > +
> > +	eop_desc = xdp_ext->pkt_ctx.eop_desc;
> > +	ptype = ice_get_ptype(eop_desc);
> > +
> > +	status = ice_get_rx_csum_status(eop_desc, ptype);
> > +	if (status & ICE_RX_CSUM_NONE)
> > +		return -ENODATA;
> > +
> > +	*csum_status = ice_rx_csum_lvl(status) + 1;
> > +	return 0;
> > +}
> 
> and xdp_csum_info from previous patch left uninitialized?
> What was the point adding it then?

I suppose this driver only returns CHECKSUM_NONE or
CHECKSUM_UNNECESSARY? Also based on a grep of the driver dir.

In general the layout makes sense to me, and +1 on supporting
other drivers that do return CHECKSUM_COMPLETE or CHECKSUM_PARTIAL
rigth from the start.