linux-kernel - Re: [PATCH 3/3] tpm: ibmvtpm: Add support for TPM 2

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Message-ID: <1e301947-a8f3-0b7d-d86c-5bfe04a68a75@linux.ibm.com>
Date:   Thu, 13 Feb 2020 14:15:03 -0500
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     Nayna <nayna@...ux.vnet.ibm.com>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>,
        linux-integrity@...r.kernel.org, aik@...abs.ru,
        david@...son.dropbear.id.au, linux-kernel@...r.kernel.org,
        gcwilson@...ux.ibm.com
Subject: Re: [PATCH 3/3] tpm: ibmvtpm: Add support for TPM 2

On 2/13/20 2:11 PM, Jason Gunthorpe wrote:
> On Thu, Feb 13, 2020 at 02:04:12PM -0500, Stefan Berger wrote:
>> On 2/13/20 1:35 PM, Jason Gunthorpe wrote:
>>> On Thu, Feb 13, 2020 at 01:20:12PM -0500, Stefan Berger wrote:
>>>
>>>> I don't want side effects for the TPM 1.2 case here, so I am only modifying
>>>> the flag for the case where the new TPM 2 is being used.  Here's the code
>>>> where it shows the effect.
>>> I'm surprised this driver is using AUTO_STARTUP, it was intended for
>>> embedded cases where their is no firmware to boot the TPM.
>> The TIS is also using it on any device.
> TIS is a generic driver, and can run on TPMs without firmware
> support. It doesn't know either way

The following drivers are all using it:


drivers/char/tpm/st33zp24/st33zp24.c, line 493
drivers/char/tpm/tpm-interface.c, line 374
drivers/char/tpm/tpm_crb.c, line 421
drivers/char/tpm/tpm_ftpm_tee.c, line 184
drivers/char/tpm/tpm_i2c_atmel.c, line 139
drivers/char/tpm/tpm_i2c_infineon.c, line 602
drivers/char/tpm/tpm_i2c_nuvoton.c, line 465
drivers/char/tpm/tpm_tis_core.c, line 917
drivers/char/tpm/tpm_vtpm_proxy.c, line 435

https://elixir.bootlin.com/linux/latest/ident/TPM_OPS_AUTO_STARTUP


>
>>> Chips using AUTO_STARTUP are basically useless for PCRs/etc.
>>>
>>> I'd expect somthing called vtpm to have been started and PCRs working
>>> before Linux is started??
>> Yes, there's supposed to be firmware.
>>
>> I only see one caller to tpm2_get_cc_attrs_tbl(chip), which is necessary to
>> call. This caller happens to be in tpm2_auto_startup.
> That seems to be a mistake, proper startup of the driver should never
> require auto_startup.

Is this IBM vTPM driver special that it should do things differently 
than all those drivers listed above? From looking at the code is seems 
it is to be set for the TPM 2.0 case.


   Stefan