linux-kernel - Re: [RESEND][RFC] tpm_tis: broken on TPMs with a static burst count

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Date:   Tue, 10 Jan 2017 00:44:14 +0100
From:   "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     tpmdd-devel@...ts.sourceforge.net,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        Christophe Ricard <christophe.ricard@...il.com>
Subject: Re: [RESEND][RFC] tpm_tis: broken on TPMs with a static burst count

Hi Jarkko,

On 09.01.2017 23:09, Jarkko Sakkinen wrote:
> On Wed, Jan 04, 2017 at 06:47:52PM +0100, Maciej S. Szmigiero wrote:
>> (Resending as no reply received, this time with CCs to TPM maintainers and
>> author of the original commit).
>>
>> Hi all,
>>
>> Commit 1107d065fdf1 (tpm_tis: Introduce intermediate layer for TPM access)
>> broke TPM support on ThinkPad X61S (and likely also on other machines which
>> use TPMs with a static burst count).
>>
>> It looks like tpm_tis code before this commit had spun on TPM_STS_DATA_AVAIL |
>> TPM_STS_VALID status bits in the read case and TPM_STS_VALID in the write case
>> when it got a zero burst count.
>>
>> I have attached a patch against current code (linux-tpmdd tree) that brings
>> back this old behavior.
>> With this patch the TPM works again on X61S.
>> However, somebody with more TPM experience should comment whether such behavior
>> was OK or the change brought by commit 1107d065fdf1 was intentional.
>>
> 
> For me this commit makes perfect sense. Could you do the following things:
> 
> 1. Clean up the description a little bit
> 2. Add your Signed-off-by tag.
> 3. Add "Cc: stable@...r.kernel.org" tag right after your signed-off-by.
> 4. CC this linux-security-module@...r.kernel.org, stable@...r.kernel.org,
>    linux-kernel@...r.kernel.org.
> 5. Run scripts/checkpatch.pl
> 6. Re-send for review.

Yes, I will respin this as a proper submission, just wanted to make sure
that it makes sense to restore the old behavior.

> Thanks for fixing the issue. Keep up the good work!

Thanks for kind words and all your TPM work!

> /Jarkko

Maciej