linux-kernel - Re: [PATCH V3 0/3] Add OP-TEE based bnxt f/w manager

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Message-ID: <74e019d5-25cf-b2e8-6f54-9afbefa28568@gmail.com>
Date:   Thu, 24 Oct 2019 17:06:42 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Sheetal Tigadoli <sheetal.tigadoli@...adcom.com>,
        Rafał Miłecki <zajec5@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michal Simek <michal.simek@...inx.com>,
        Rajan Vaja <rajan.vaja@...inx.com>,
        Scott Branden <scott.branden@...adcom.com>,
        Ray Jui <ray.jui@...adcom.com>,
        Vikram Prakash <vikram.prakash@...adcom.com>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        Michael Chan <michael.chan@...adcom.com>,
        "David S. Miller" <davem@...emloft.net>,
        Vikas Gupta <vikas.gupta@...adcom.com>,
        Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        tee-dev@...ts.linaro.org, bcm-kernel-feedback-list@...adcom.com,
        netdev@...r.kernel.org
Subject: Re: [PATCH V3 0/3] Add OP-TEE based bnxt f/w manager

On 10/24/19 11:39 AM, Florian Fainelli wrote:
> On 10/23/19 10:32 PM, Sheetal Tigadoli wrote:
>> This patch series adds support for TEE based BNXT firmware
>> management module and the driver changes to invoke OP-TEE
>> APIs to fastboot firmware and to collect crash dump.
> 
> Sorry for chiming on this so late, the more I look into this and the
> more it seems like you have built a custom TEE firmware loading solution
> rather than thinking about extending the firmware API to load a firmware
> opaque handle from somewhere other than the filesystem.
> 
> The TEE integration appears okay to me in that you leverage the TEE bus
> to advertise your driver. What seems to violating layers is that you
> have bnxt directly tap into your TEE driver's services and that looks
> not ideal to say the least. That approach does not scale well over
> multiple drivers (bnxt or otherwise), but also does not really scale
> over trusted components providers. TEE is one of them, but conceptually
> the same thing could exist with ACPI/UEFI or any platform that has
> services that offer some sort of secure/non-secured world differentiation.
> 
> The way I would imagine you to integrate this is to basically register a
> TEE firmware provider through the firmware API, continue using the
> firmware API from within bnxt, possibly with using a specific file
> handle/flag that designates whether you want to favor loading from
> disk/file system or TEE. It should not matter to bnxt how the firmware
> is obtained basically.

And I should have probably ended this paragraph with saying that the
suggestion does not need to happen right now but would be nice to be
done as a cleanup exercise (of course, by saying that, I am also opening
the door for this to not happen at all..).
-- 
Florian