linux-kernel - Re: [PATCH v4 1/2] fTPM: firmware TPM running in TEE

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Message-ID: <20190614103430.GA6108@apalos>
Date:   Fri, 14 Jun 2019 13:34:30 +0300
From:   Ilias Apalodimas <ilias.apalodimas@...aro.org>
To:     Sasha Levin <sashal@...nel.org>
Cc:     Sumit Garg <sumit.garg@...aro.org>, peterhuewe@....de,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        jgg@...pe.ca, corbet@....net,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-doc@...r.kernel.org, linux-integrity@...r.kernel.org,
        Microsoft Linux Kernel List <linux-kernel@...rosoft.com>,
        Thirupathaiah Annapureddy <thiruan@...rosoft.com>,
        "Bryan Kelly (CSI)" <bryankel@...rosoft.com>,
        tee-dev@...ts.linaro.org
Subject: Re: [PATCH v4 1/2] fTPM: firmware TPM running in TEE

Hi Sasha, 
On Thu, Jun 13, 2019 at 01:11:41PM -0400, Sasha Levin wrote:
> On Wed, Jun 05, 2019 at 04:39:36PM +0530, Sumit Garg wrote:
> >On Wed, 5 Jun 2019 at 01:39, Sasha Levin <sashal@...nel.org> wrote:
> >>
> >>On Tue, Jun 04, 2019 at 11:45:52AM +0530, Sumit Garg wrote:
> >>>On Thu, 30 May 2019 at 20:58, Sasha Levin <sashal@...nel.org> wrote:
> >>>> +       /* Open context with TEE driver */
> >>>> +       pvt_data->ctx = tee_client_open_context(NULL, ftpm_tee_match, NULL,
> >>>> +                                               NULL);
> >>>> +       if (IS_ERR(pvt_data->ctx)) {
> >>>> +               dev_err(dev, "%s:tee_client_open_context failed\n", __func__);
> >>>
> >>>Is this well tested? I see this misleading error multiple times as
> >>>follows although TEE driver works pretty well.
> >>
> >>Yes, this was all functionally tested.
I did test as well with a DeveloperBox, i can confirm the driver is loading (but
i have no fTPM support on the OP-TEE side for now)


apalos@...e:~>sudo dmesg | grep optee
[sudo] password for apalos: 
[    5.035801] optee: probing for conduit method from DT.
[    5.041045] optee: revision 3.2 (53bf1c38)
[    5.041772] optee: initialized driver
apalos@...e:~>sudo dmesg | grep tpm
[    5.000674] ftpm-tee tpm@0: ftpm_tee_probe:tee_client_open_context failed
[    5.101655] ftpm-tee tpm@0: ftpm_tee_probe:tee_client_open_session failed,
err=ffff000c
[    5.109703] ftpm-tee: probe of tpm@0 failed with error -22


The error -22 is nice since the probe eventually failed (no fTPM support in
secure world). Can we slightly change the
'ftpm_tee_probe:tee_client_open_context failed' and indicate this is not a real
error since the probe gets deferred untill Secure world is alive?

By the way there is *real* interest for this functionality. I expect to run it
on a number of Arm boards once i get some free time.

> >Can you share your build instructions and testing approach?
> 
> Yes: it looks like you got all the kernel bits, but not the firmware.
> There are instructions for it here: https://github.com/microsoft/ms-tpm-20-ref
> 
> Once it's running, you can test it by running your favorite TPM usecases
> through /dev/tpm0.
> 
> --
> Thanks,
> Sasha

Thanks
/Ilias