From:   Volodymyr Mytnyk <volodymyr.mytnyk@plvision.eu>
To:     Jamal Hadi Salim <jhs@mojatatu.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>
CC:     Taras Chornyi <taras.chornyi@plvision.eu>,
        Mickey Rachamim <mickeyr@marvell.com>,
        Serhiy Pshyk <serhiy.pshyk@plvision.eu>,
        Volodymyr Mytnyk <vmytnyk@marvell.com>,
        Taras Chornyi <tchornyi@marvell.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next] net: prestera: flower template support
Thread-Topic: [PATCH net-next] net: prestera: flower template support
Thread-Index: AQHX55R72e0BLdbnYk+svnQj9X0JyKwfdDOAgAAAvSCAAAmxgIAKdbyW
Date:   Thu, 9 Dec 2021 10:46:02 +0000
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Hi Jamal,=0A=
=0A=
>=0A=
> > Hi Jamal,=0A=
> > =0A=
> >>=0A=
> >>> From: Volodymyr Mytnyk<vmytnyk@marvell.com>=0A=
> >>>=0A=
> >>> Add user template explicit support. At this moment, max TCAM rule siz=
e=0A=
> >>> is utilized for all rules, doesn't matter which and how much flower=
=0A=
> >>> matches are provided by user. It means that some of TCAM space is=0A=
> >>> wasted, which impacts the number of filters that can be offloaded.=0A=
> >>>=0A=
> >>> Introducing the template, allows to have more HW offloaded filters.=
=0A=
> >>>=0A=
> >>> Example:=0A=
> >>>     tc qd add dev PORT clsact=0A=
> >>>     tc chain add dev PORT ingress protocol ip \=0A=
> >>>       flower dst_ip 0.0.0.0/16=0A=
> >>=0A=
> >> "chain" or "filter"?=0A=
> > =0A=
> > tc chain add ... flower [tempalte] is the command to add explicitly cha=
in with a given template=0A=
> > =0A=
> =0A=
> I guess you are enforcing the template on chain 0. My brain=0A=
> was  expecting chain id to be called out.=0A=
> =0A=
=0A=
chain 0 is the default chain id for "tc chain" & "tc filter" command,=0A=
so, that's why I did not mention it in the command line. Please note,=0A=
this patch adds only template support. Chains are not supported yet,=0A=
and will be added later.=0A=
=0A=
> =0A=
> > tc filter ... is the command to add a filter itself in that chain=0A=
> > =0A=
> =0A=
> Got it.=0A=
> =0A=
> =0A=
> >> You are not using tc priority? Above will result in two priorities (th=
e 0.0.0.0 entry will be more important) and in classical flower approach tw=
o  different tables.=0A=
> >> I am wondering how you map the table to the TCAM.=0A=
> >> Is the priority sorting entirely based on masks in hardware?=0A=
> > =0A=
> > Kernel tc filter priority is used as a priority for HW rule (see flower=
 implementation).=0A=
> =0A=
> The TCAM however should be able to accept many masks - is the idea=0A=
> here to enforce some mask per chain and then have priority being the=0A=
> priorities handle conflict? What happens when you explicitly specify=0A=
> priority. If you dont specify it the kernel provides it and essentially=
=0A=
> resolution is based on the order in which the rules are entered..=0A=
=0A=
The HW rule insert/delete into TCAM is done by the FW itself. It means,=0A=
that the FW will take care about prio and (re)order the rule based on the=
=0A=
priority provided by user/kernel. So, kernel driver just need to provide=0A=
prio to the FW when adding the rule into the HW.=0A=
=0A=
> =0A=
> cheers,=0A=
> jamal=0A=
=0A=
Thanks and Regards,=0A=
  Volodymyr=