linux-kernel - Re: [PATCH v3] tpm_tis: Add missing tpm_request/relinquish

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Message-ID: <YBswlPuVINENIoUC@kernel.org>
Date:   Thu, 4 Feb 2021 01:24:04 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Lukasz Majczak <lma@...ihalf.com>
Cc:     Dirk Gouders <dirk@...ders.net>,
        Guenter Roeck <linux@...ck-us.net>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        Tj <ml.linux@...oe.vision>, Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        Radoslaw Biernacki <rad@...ihalf.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Alex Levin <levinale@...gle.com>
Subject: Re: [PATCH v3] tpm_tis: Add missing tpm_request/relinquish_locality
 calls

On Wed, Feb 03, 2021 at 02:43:44PM +0100, Lukasz Majczak wrote:
> Hi Jarkko, Dirk,
> 
> Jarkko,
> Thank you for your points - I will try to fix all you have mentioned.
> I think it would be good to clarify a few things, before going with
> the next version. Regarding use tpm_chip_start/stop() around
> tpm2_probe() call - I have followed the similar way it is done in the
> probe_itpm() function, where is also a call to tpm_tis_send_data()
> guarded by request/release_locality(). I have tested it on the Samsung
> Chromebook Pro (which reports TPM 1.2 / Cr50) and it was sufficient
> (e.g. I didn't have to enable the clock) to get rid of a trace
> mentioned in the commit message....but now writing these words I'm
> starting to think that using tpm_chip_start/stop() could be safer from
> a point of view of other TPMs... so if you suggest using
> tpm_chip_start/stop() shall I also add it to the probe_itpm() (instead
> of  request/release_locality()) ?
> 
> Dirk,
> Thanks for the clarification. Regarding the issue you observe - I
> wanted to address at first the one that is generating the trace
> (please check the commit message) because it was leading to returning
> an error in the tpm_tis_status() function causing TPM module not
> initialized at all in the end - requesting locality before the call to
> the tpm_tis_send_data() has helped in my case (my test environment). I
> am aware of the second issue - "TPM interrupt not working, polling
> instead", but as it is not as critical as the first one, I decided to
> work on it later.
> 
> Thank you once again for all your input and sorry for a confusion with
> sending patches.

NP, thanks for doing this. Just take your time and polish the cosmetic
things. Especially for bug fixes a clean changelog is essential.

> Best regards,
> Lukasz

/Jarkko