Re: [PATCH v4 net-next 1/8] sfc: add devlink support for ef100

From: Jakub Kicinski <kuba@kernel.org>
To: Martin Habets <habetsm.xilinx@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>,
	"Lucero Palau, Alejandro" <alejandro.lucero-palau@amd.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-net-drivers (AMD-Xilinx)" <linux-net-drivers@amd.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"pabeni@redhat.com" <pabeni@redhat.com>,
	"edumazet@google.com" <edumazet@google.com>,
	"ecree.xilinx@gmail.com" <ecree.xilinx@gmail.com>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"corbet@lwn.net" <corbet@lwn.net>,
	"jiri@nvidia.com" <jiri@nvidia.com>
Subject: Re: [PATCH v4 net-next 1/8] sfc: add devlink support for ef100
Date: Thu, 2 Feb 2023 09:43:59 -0800	[thread overview]
Message-ID: <20230202094359.7a79ee6d@kernel.org> (raw)
In-Reply-To: <Y9uA8Vk430k+ezTt@gmail.com>

On Thu, 2 Feb 2023 09:24:56 +0000 Martin Habets wrote:
> > FWIW I'd just take the devl lock in the main driver code.
> > devlink should be viewed as a layer between bus and driver rather 
> > than as another subsystem the driver registers with. Otherwise reloads
> > and port creation get awkward.  
> 
> I see it a bit differently. For me devlink is another subsystem, it even is
> an optional subsystem.
> At the moment we don't support devlink port for VFs. If needed we'll add that
> at some point, but likely only for newer NICs.

That's fine. I believe the structure I suggest is the easiest one 
to get right, but it's not a hard requirement.

> Do you think vDPA and RDMA devices will ever register with devlink?

Good question, I can't speak for the entire project but personally 
I have little interest in interfaces to proprietary world, 
so I hope not.

> At the moment I don't see devlink port ever applying to our older hardware,
> like our sfn8000 or X2 cards. I do think devlink info and other commands
> could apply more generally.
> 
> There definitely is a need to evolve to another layer between bus and
> devices, and devlink can be used to administer that. But that does not
> imply the reverse, that all devices register as devlink devices.
> For security we would want to limit some operations (such as port creation)
> to specific devlink instance(s). For example, normally we would not want a
> tennant VM to flash new firmware that applies to the whole NIC.
> I hope this makes sense.