linux-kernel - Re: [PATCH v3 1/2] ftpm: firmware TPM running in TEE

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Date:   Fri, 17 May 2019 09:22:26 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     peterhuewe@....de, jgg@...pe.ca, corbet@....net,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-kernel@...rosoft.com,
        thiruan@...rosoft.com, bryankel@...rosoft.com
Subject: Re: [PATCH v3 1/2] ftpm: firmware TPM running in TEE

On Wed, May 15, 2019 at 11:12:50AM +0300, Jarkko Sakkinen wrote:
>On Mon, Apr 15, 2019 at 11:56:35AM -0400, Sasha Levin wrote:
>> This patch adds support for a software-only implementation of a TPM
>> running in TEE.
>>
>> There is extensive documentation of the design here:
>> https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/ .
>>
>> As well as reference code for the firmware available here:
>> https://github.com/Microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM
>
>The commit message should include at least a brief description what TEE
>is.

The whole TEE subsystem is already well documented in our kernel tree
(https://www.kernel.org/doc/Documentation/tee.txt) and beyond. I can add
a reference to the doc here, but I'd rather not add a bunch of TEE
related comments as you suggest later in your review.

The same way a PCI device driver doesn't describe what PCI is in it's
code, we shouldn't be doing the same for TEE here.

>> +
>> +#include <linux/of.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/acpi.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/tee_drv.h>
>> +#include <linux/uuid.h>
>> +#include <linux/tpm.h>
>> +
>> +#include "tpm.h"
>> +#include "tpm_ftpm_tee.h"
>> +
>> +#define DRIVER_NAME "ftpm-tee"
>> +
>> +/* TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896 */
>> +static const uuid_t ftpm_ta_uuid =
>> +	UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4,
>> +		  0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96);
>
>Just wondering why prefixes are here in different order in the comment
>and code.

No prefixes, this is a completely randomly generated UUID.

I'll address the rest of your comments in the next ver.

--
Thanks,
Sasha