linux-kernel - Re: [PATCH v4 0/2] generate boot_aggregate log in IMA with TPM using CRB over FF-A

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Message-ID: <20250625-chital-of-infinite-proficiency-fee4dc@sudeepholla>
Date: Wed, 25 Jun 2025 20:35:33 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Jarkko Sakkinen <jarkko@...nel.org>
Cc: Yeoreum Yun <yeoreum.yun@....com>, peterhuewe@....de, jgg@...pe.ca,
	stuart.yoder@....com, linux-arm-kernel@...ts.infradead.org,
	Sudeep Holla <sudeep.holla@....com>, linux-kernel@...r.kernel.org,
	linux-integrity@...r.kernel.org
Subject: Re: [PATCH v4 0/2] generate boot_aggregate log in IMA with TPM using
 CRB over FF-A

On Wed, Jun 25, 2025 at 08:01:51PM +0300, Jarkko Sakkinen wrote:
> On Wed, Jun 25, 2025 at 07:59:53PM +0300, Jarkko Sakkinen wrote:
> > On Wed, Jun 25, 2025 at 11:36:19AM +0100, Yeoreum Yun wrote:
> > > Hi Jarkko,
> > > 
> > > > On Wed, Jun 18, 2025 at 11:23:00AM +0100, Yeoreum Yun wrote:
> > > > > To ensure the TPM device operating over the FF-A protocol with
> > > > > the CRB interface is probed before IMA initialization,
> > > > > the following conditions must be met:
> > > > >
> > > > >    1. The corresponding ffa_device must be registered,
> > > > >       which is done via ffa_init().
> > > > >
> > > > >    2. The tpm_crb_driver must successfully probe this device via
> > > > >       tpm_crb_ffa_init().
> > > > >
> > > > >    3. The tpm_crb driver using CRB over FF-A can then
> > > > >       be probed successfully. (See crb_acpi_add() and
> > > > >       tpm_crb_ffa_init() for reference.)
> > > > >
> > > > > Unfortunately, ffa_init(), tpm_crb_ffa_init(), and crb_acpi_driver_init() are
> > > > > all registered with device_initcall, which means crb_acpi_driver_init() may
> > > > > be invoked before ffa_init() and tpm_crb_ffa_init() are completed.
> > > >
> > > > I get the ffa_init() part i.e, moving it earlier. However for
> > > > tpm_crb_ffa_init() and crb_acpi_driver_init(), modules.dep
> > > > takes care that they are loaded in order.
> > > > For IMA you will need the driver as built-in but that should
> > > > be handled via kernel config, not via code changes.
> > > 
> > > In the case of "module" built, it's true.
> > > However what I tell here is when "tpm_crb" and "tpm_crb_ffa" is built
> > > as "built-in" in this case, it couldn't make a "dependency" between
> > > the same initcall level: here is the case of this.
> > > 
> > > 0000000000000888 l       .initcall6.init>-------0000000000000000 crb_acpi_driver_init
> > > 000000000000088c l       .initcall6.init>-------0000000000000000 tpm_crb_ffa_driver_init
> > > 
> > > in this case, wihtout code change, the crb_acpi_driver_init()
> > > is failed since tpm_crb_ffa_driver_init() is called later.
> > > 
> > > and this couldn't be solved with kconfig --
> > > ARM_FFA_TRANSPORT=y && CONFIG_TCG_CRB=y && CONFIG_TCG_CRB_FFA=y.
> > > 
> > > The Patch #2 is to proing the tpm_crb_ffa as part of
> > > crb_acpi_driver_init() when TPM uses method ARM-FFA.
> > > 
> > > If there's another suggestion, let me know please.
> > 
> > Hmm.. I actually got what you mean now. I was looking this from
> > wrong angle. I think we can pick these patches!
> > 
> > Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
> > 
> > > 
> > > Thanks
> > > 
> > > --
> > > Sincerely,
> > > Yeoreum Yun
> > 
> > BR, Jarkko
> 
> Applied.

If you are applying 1/2 too, feel free to add

Reviewed-by: Sudeep Holla <sudeep.holla@....com>

I was initially thinking of taking it separately as there is no strict
build dependency. But I am fine if you can take them together.

-- 
Regards,
Sudeep