linux-kernel - Re: [PATCH] x86: tpm: Remove a busy bit of the NVS area for supporting AMD's fTPM

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Date:   Wed, 28 Aug 2019 18:36:04 +0900
From:   Seunghun Han <kkamagui@...il.com>
To:     Matthew Garrett <mjg59@...f.ucam.org>
Cc:     Matthew Garrett <mjg59@...gle.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>,
        "open list:TPM DEVICE DRIVER" <linux-integrity@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: tpm: Remove a busy bit of the NVS area for
 supporting AMD's fTPM

>
> On Wed, Aug 28, 2019 at 01:36:30AM +0900, Seunghun Han wrote:
>
> > I got your point. Is there any problem if some regions which don't
> > need to be handled in NVS area are saved and restored? If there is a
> > problem, how about adding code for ignoring the regions in NVS area to
> > the nvs.c file like Jarkko said? If we add the code, we can save and
> > restore NVS area without driver's interaction.
>
> The only thing that knows which regions should be skipped by the NVS
> driver is the hardware specific driver, so the TPM driver needs to ask
> the NVS driver to ignore that region and grant control to the TPM
> driver.
>
> --
> Matthew Garrett | mjg59@...f.ucam.org

Thank you, Matthew and Jarkko.
It seems that the TPM driver needs to handle the specific case that
TPM regions are in the NVS. I would make a patch that removes TPM
regions from the ACPI NVS by requesting to the NVS driver soon.

Jarkko,
I would like to get some advice on it. What do you think about
removing TPM regions from the ACPI NVS in TPM CRB driver? If you don't
mind, I would make the patch about it.

Seunghun