linux-kernel - Re: [PATCH v4 3/7] tpm: tpm_tis: rewrite "tpm_tis_req

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Message-ID: <774fa2af-e4a6-4577-f1f7-c786e3b5210c@linux.ibm.com>
Date:   Tue, 31 Mar 2020 09:52:15 -0400
From:   Ken Goldman <kgold@...ux.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        amirmizi6@...il.com
Cc:     Eyal.Cohen@...oton.com, oshrialkoby85@...il.com,
        alexander.steffen@...ineon.com, robh+dt@...nel.org,
        mark.rutland@....com, peterhuewe@....de, jgg@...pe.ca,
        arnd@...db.de, gregkh@...uxfoundation.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-integrity@...r.kernel.org, oshri.alkoby@...oton.com,
        tmaimon77@...il.com, gcwilson@...ibm.com, kgoldman@...ibm.com,
        Dan.Morav@...oton.com, oren.tanami@...oton.com,
        shmulik.hager@...oton.com, amir.mizinski@...oton.com
Subject: Re: [PATCH v4 3/7] tpm: tpm_tis: rewrite "tpm_tis_req_canceled()"

On 3/31/2020 8:13 AM, Jarkko Sakkinen wrote:
> On Tue, Mar 31, 2020 at 02:32:03PM +0300, amirmizi6@...il.com wrote:
>> From: Amir Mizinski <amirmizi6@...il.com>
>>
>> Using this function while read/write data resulted in aborted operation.
>> After investigating according to TCG TPM Profile (PTP) Specifications,
>> i found cancel should happen only if TPM_STS.commandReady bit is lit and
>> couldn't find a case when the current condition is valid.
>> Also only cmdReady bit need to be compared instead of the full lower status
>> register byte.
>>
>> Signed-off-by: Amir Mizinski <amirmizi6@...il.com>
> 
> We don't care about spec's. We care about hardware and not all hardware
> follows specifications.
> 
> Please fix the exact thing you want to fix (and please provide a fixes
> tag).

I edit the TPM main spec, not the PTP.  As I discover TPMs that don't 
meet the spec, or where the spec has changed over time, I add 
informative comments to guide developers.

If you know of TPM hardware that does not meet the PTP specification, 
let me know the specifics.  I can bring it to the PTP work group and try 
to get comments added.

I do not need to know the TPM vendor.  That information would not go 
into the specification anyway.