linux-kernel - Re: [net-next PATCH v2 5/9] octeontx2-af: Add packet path between representor and VF

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Date: Thu, 25 Apr 2024 06:01:47 +0000
From: Sunil Kovvuri Goutham <sgoutham@...vell.com>
To: Jiri Pirko <jiri@...nulli.us>, Geethasowjanya Akula <gakula@...vell.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "davem@...emloft.net"
	<davem@...emloft.net>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        Subbaraya Sundeep Bhatta
	<sbhatta@...vell.com>,
        Hariprasad Kelam <hkelam@...vell.com>
Subject: Re: [net-next PATCH v2 5/9] octeontx2-af: Add packet path between
 representor and VF



> -----Original Message-----
> From: Jiri Pirko <jiri@...nulli.us>
> Sent: Tuesday, April 23, 2024 6:39 PM
> To: Geethasowjanya Akula <gakula@...vell.com>
> Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org; kuba@...nel.org;
> davem@...emloft.net; pabeni@...hat.com; edumazet@...gle.com; Sunil
> Kovvuri Goutham <sgoutham@...vell.com>; Subbaraya Sundeep Bhatta
> <sbhatta@...vell.com>; Hariprasad Kelam <hkelam@...vell.com>
> Subject: [EXTERNAL] Re: [net-next PATCH v2 5/9] octeontx2-af: Add packet
> path between representor and VF
> 
> Mon, Apr 22, 2024 at 11:53:57AM CEST, gakula@...vell.com wrote:
> >This patch installs tcam rules to stree traffic representors and VF
> >when swicthdev mode is set. To support this a HW loopback channel is
> >reserved. Through this channel packet are routed between representor
> >and VFs. "ESW_CFG" mbox is defined to notify AF for installing rules.
> 
> This sounds very wrong. In switchdev mode, there is no implicit packet
> forwarding. User configures that, either by setting up TC filters to
> match/forward packets, putting representors in a bridge, etc.
> Basically the driver offloads whatever configuration on representors the user
> does, in case it supports it.
> 
> Please make sure you follow that.

In our HW, there is no in-built switch which will forward pkts between representee and representor.
When representor is put under a bridge and pkts needs to be sent to representee, then pkts from
representor are sent on a HW internal loopback channel, which again will be punted to ingress
pkt parser. Now the rules that this patch installs are the MCAM filters/rules which will match against
these pkts and forward them to representee.

To be more clear the rules that this patch installs are for basic representor <-=> representee path
similar to Tun/TAP between VM and Host. Now for any further offloads (eg: L2 or ConnTrk)
user will have to install explicit rules via TC filters.

Thanks,
Sunil.