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From: Sasha Levin <sashal@kernel.org>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: robh+dt@kernel.org, mark.rutland@arm.com, peterhuewe@gmx.de,
	jgg@ziepe.ca, linux-kernel@microsoft.com, bryankel@microsoft.com,
	thiruan@microsoft.com, suredd@microsoft.com, arnd@arndb.de,
	gregkh@linuxfoundation.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org
Subject: Re: [PATCH 2/2] ftpm: firmware TPM running in TEE
Date: Sat, 6 Apr 2019 11:30:47 -0400	[thread overview]
Message-ID: <20190406153047.GF2935@sasha-vm> (raw)
In-Reply-To: <20190403182728.GA17451@linux.intel.com>

On Wed, Apr 03, 2019 at 09:27:28PM +0300, Jarkko Sakkinen wrote:
>On Wed, Apr 03, 2019 at 09:18:27PM +0300, Jarkko Sakkinen wrote:
>> On Tue, Apr 02, 2019 at 03:33:16PM -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
>> >
>> > Signed-off-by: Thirupathaiah Annapureddy <thiruan@microsoft.com>
>> > Signed-off-by: Sasha Levin <sashal@kernel.org>
>>
>> What is the context anyway? I mean tpm_crb already supports fTPM running
>> in TZ.
>
>Might take 2-3 weeks before I have time to go through ftpm1.pdf with
>full concentration. I did search through the PDF for CRB and found
>zero hits.

The fTPM as described in that paper and implemented in practice does not
use the CRB interface, thus we can't use tpm_crb to interface with the
firmware TPM.

>The commit message should absolutely better explain what is going on
>and preferably there should be some more broad documentation in
>Documentation/security/tpm.

The code itself is just a small shim between the firmware TPM and the
kernel's TPM interface. There's really not much else to expand on in the
commit log.

I'll add some background to Documentation/security/tpm.

>Now this is just a random code dump and nothing else.

It pretty much is, but that's because this is just a "stupid" shim,
there heavy lifting is done outside of the kernel.

>Also, I have zero idea how to test this. Any recommendations on ARM
>board that can be easily used to test custom TZ applications would be
>nice.

We are testing this on a Broadcom's Stingray SST100 board, and if you
have one we can help out with setting up a test environment. Otherwise,
we haven't really tried it on other boards.

--
Thanks,
Sasha

  reply	other threads:[~2019-04-06 15:30 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-02 19:33 [PATCH 1/2] ftpm: dt-binding: add dts documentation for fTPM driver Sasha Levin
2019-04-02 19:33 ` [PATCH 2/2] ftpm: firmware TPM running in TEE Sasha Levin
2019-04-02 20:56   ` Stephen Hemminger
2019-04-03 18:19     ` Jarkko Sakkinen
2019-04-03 12:40   ` Jason Gunthorpe
2019-04-03 18:18   ` Jarkko Sakkinen
2019-04-03 18:27     ` Jarkko Sakkinen
2019-04-06 15:30       ` Sasha Levin [this message]
2019-04-10 11:29         ` Jarkko Sakkinen
2019-04-10 16:04           ` Sasha Levin
2019-04-10 17:38             ` Jarkko Sakkinen
2019-04-02 19:37 ` [PATCH 1/2] ftpm: dt-binding: add dts documentation for fTPM driver Greg KH
2019-04-02 20:03   ` Sasha Levin
2019-04-03 18:15 ` Jarkko Sakkinen

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