linux-kernel - Re: [PATCH v1 00/17] tee: Use bus callbacks instead of driver callbacks

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

Message-ID: <dhunzydod4d7vj73llpuqemxb5er2ja4emxusr66irwf77jhhb@es4yd2axzl25>
Date: Mon, 15 Dec 2025 10:32:18 +0100
From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
To: Sumit Garg <sumit.garg@...nel.org>
Cc: Jens Wiklander <jens.wiklander@...aro.org>, 
	Olivia Mackall <olivia@...enic.com>, Herbert Xu <herbert@...dor.apana.org.au>, 
	Clément Léger <clement.leger@...tlin.com>, Alexandre Belloni <alexandre.belloni@...tlin.com>, 
	Ard Biesheuvel <ardb@...nel.org>, Maxime Coquelin <mcoquelin.stm32@...il.com>, 
	Alexandre Torgue <alexandre.torgue@...s.st.com>, Sumit Garg <sumit.garg@....qualcomm.com>, 
	Ilias Apalodimas <ilias.apalodimas@...aro.org>, Jan Kiszka <jan.kiszka@...mens.com>, 
	Sudeep Holla <sudeep.holla@....com>, Christophe JAILLET <christophe.jaillet@...adoo.fr>, 
	Michael Chan <michael.chan@...adcom.com>, Pavan Chebbi <pavan.chebbi@...adcom.com>, 
	Rafał Miłecki <zajec5@...il.com>, James Bottomley <James.Bottomley@...senpartnership.com>, 
	Jarkko Sakkinen <jarkko@...nel.org>, Mimi Zohar <zohar@...ux.ibm.com>, 
	David Howells <dhowells@...hat.com>, Paul Moore <paul@...l-moore.com>, 
	James Morris <jmorris@...ei.org>, "Serge E. Hallyn" <serge@...lyn.com>, 
	Peter Huewe <peterhuewe@....de>, op-tee@...ts.trustedfirmware.org, linux-kernel@...r.kernel.org, 
	linux-crypto@...r.kernel.org, linux-rtc@...r.kernel.org, linux-efi@...r.kernel.org, 
	linux-stm32@...md-mailman.stormreply.com, linux-arm-kernel@...ts.infradead.org, 
	Cristian Marussi <cristian.marussi@....com>, arm-scmi@...r.kernel.org, netdev@...r.kernel.org, 
	linux-mips@...r.kernel.org, linux-integrity@...r.kernel.org, keyrings@...r.kernel.org, 
	linux-security-module@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>
Subject: Re: [PATCH v1 00/17] tee: Use bus callbacks instead of driver
 callbacks

Hello Sumit,

On Mon, Dec 15, 2025 at 04:54:11PM +0900, Sumit Garg wrote:
> On Thu, Dec 11, 2025 at 06:14:54PM +0100, Uwe Kleine-König wrote:
> > Hello,
> > 
> > the objective of this series is to make tee driver stop using callbacks
> > in struct device_driver. These were superseded by bus methods in 2006
> > (commit 594c8281f905 ("[PATCH] Add bus_type probe, remove, shutdown
> > methods.")) but nobody cared to convert all subsystems accordingly.
> > 
> > Here the tee drivers are converted. The first commit is somewhat
> > unrelated, but simplifies the conversion (and the drivers). It
> > introduces driver registration helpers that care about setting the bus
> > and owner. (The latter is missing in all drivers, so by using these
> > helpers the drivers become more correct.)
> > 
> > The patches #4 - #17 depend on the first two, so if they should be
> > applied to their respective subsystem trees these must contain the first
> > two patches first.
> 
> Thanks Uwe for your efforts to clean up the boilerplate code for TEE bus
> drivers.

Thanks for your feedback. I will prepare a v2 and address your comments
(whitespace issues and wrong callback in the shutdown method).

> > Note that after patch #2 is applied, unconverted drivers provoke a
> > warning in driver_register(), so it would be good for the user
> > experience if the whole series goes in during a single merge window.
> 
> +1
> 
> I suggest the whole series goes via the Jens tree since there shouldn't
> be any chances for conflict here.
> 
> > So
> > I guess an immutable branch containing the frist three patches that can
> > be merged into the other subsystem trees would be sensible.
> > 
> > After all patches are applied, tee_bus_type can be made private to
> > drivers/tee as it's not used in other places any more.
> > 
> 
> Feel free to make the tee_bus_type private as the last patch in the series
> such that any followup driver follows this clean approach.

There is a bit more to do for that than I'm willing to invest. With my
patch series applied `tee_bus_type` is still used in
drivers/tee/optee/device.c and drivers/tee/tee_core.c. Maybe it's
sensible to merge these two files into a single one.

The things I wonder about additionally are:

 - if CONFIG_OPTEE=n and CONFIG_TEE=y|m the tee bus is only used for
   drivers but not devices.

 - optee_register_device() calls device_create_file() on
   &optee_device->dev after device_register(&optee_device->dev).
   (Attention half-knowledge!) I think device_create_file() should not
   be called on an already registered device (or you have to send a
   uevent afterwards). This should probably use type attribute groups.
   (Or the need_supplicant attribute should be dropped as it isn't very
   useful. This would maybe be considered an ABI change however.)

 - Why does optee_probe() in drivers/tee/optee/smc_abi.c unregister all
   optee devices in its error path (optee_unregister_devices())?

Best regards
Uwe

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)