linux-kernel - Re: [PATCH v2] tpm: use a map for tpm2_calc_ordinal

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Message-ID: <aMxfdLZeQWha0tQg@kernel.org>
Date: Thu, 18 Sep 2025 22:37:24 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Frédéric Jouen <fjouen@...lsq.com>,
	Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	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>,
	open list <linux-kernel@...r.kernel.org>,
	"open list:KEYS-TRUSTED" <keyrings@...r.kernel.org>,
	"open list:SECURITY SUBSYSTEM" <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH v2] tpm: use a map for tpm2_calc_ordinal_duration()

On Thu, Sep 18, 2025 at 10:30:18PM +0300, Jarkko Sakkinen wrote:
> The current shenanigans for duration calculation introduce too much
> complexity for a trivial problem, and further the code is hard to patch and
> maintain.
> 
> Address these issues with a flat look-up table, which is easy to understand
> and patch. If leaf driver specific patching is required in future, it is
> easy enough to make a copy of this table during driver initialization and
> add the chip parameter back.
> 
> 'chip->duration' is retained for TPM 1.x.
> 
> As the first entry for this new behavior address TCG spec update mentioned
> in this issue:
> 
> https://github.com/raspberrypi/linux/issues/7054
> 
> Therefore, for TPM_SelfTest the duration is set to 3000 ms.
> 
> This does not categorize a as bug, given that this is introduced to the
> spec after the feature was originally made.
> 
> Cc: Frédéric Jouen <fjouen@...lsq.com>
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> ---
> v2:
> - Add the missing msec_to_jiffies() calls.
> - Drop redundant stuff.

Run also through kselftest.

BR, Jarkko