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

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Date:   Thu, 13 Feb 2020 15:11:08 -0400
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Stefan Berger <stefanb@...ux.ibm.com>
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 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

> > 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.

Jason