linux-kernel - Re: [PATCH net-next v2 12/14] net: ethernet: qualcomm: Initialize PPE L2 bridge settings

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <8bdde187-b329-480d-a745-16871276a331@lunn.ch>
Date: Mon, 13 Jan 2025 14:37:53 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Lei Wei <quic_leiwei@...cinc.com>
Cc: Luo Jie <quic_luoj@...cinc.com>, Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Suruchi Agarwal <quic_suruchia@...cinc.com>,
	Pavithra R <quic_pavir@...cinc.com>,
	Simon Horman <horms@...nel.org>, Jonathan Corbet <corbet@....net>,
	Kees Cook <kees@...nel.org>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	linux-arm-msm@...r.kernel.org, netdev@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-hardening@...r.kernel.org,
	quic_kkumarcs@...cinc.com, quic_linchen@...cinc.com,
	srinivas.kandagatla@...aro.org, bartosz.golaszewski@...aro.org,
	john@...ozen.org
Subject: Re: [PATCH net-next v2 12/14] net: ethernet: qualcomm: Initialize
 PPE L2 bridge settings

> > Why is learning needed on physical ports? In general, switches forward
> > unknown destination addresses to the CPU. Which is what you want when
> > the ports are isolated from each other. Everything goes to the
> > CPU. But maybe this switch does not work like this?
> > 
> 
> L2 forwarding can be disabled in PPE in two ways:
> 
> 1.) Keep the learning enabled (which is the default HW setting) and
> configure the FDB-miss-action to redirect to CPU.
> 
> This works because even if FDB learning is enabled, we need to represent
> the bridge and the physical ports using their 'virtual switch instance'
> (VSI) in the PPE HW, and create the 'port membership' for the bridge VSI
> (the list of slave ports), before FDB based forwarding can take place. Since
> we do not yet support switchdev, these VSI are not created and packets are
> always forwarded to CPU due to FDB miss.
> 
> (or)
> 
> 2.) Explicitly disable learning either globally or on the ports.
> 
> With method 1 we can achieve packet forwarding to CPU without explicitly
> disabling learning. When switchdev is enabled later, L2 forwarding can be
> enabled as a natural extension on top of this configuration. So we have
> chosen the first approach.

How does ageing work in this setup? Will a cable unplug/plug flush all
the learned entries? Is ageing set to some reasonable default in case
a MAC address moves?

	Andrew