linux-kernel - Re: [PATCH] tpm: tpm_crb: Add an AMD fTPM support feature

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Date:   Mon, 26 Aug 2019 08:59:03 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Seunghun Han <kkamagui@...il.com>
Cc:     Peter Huewe <peterhuewe@....de>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org
Subject: Re: [PATCH] tpm: tpm_crb: Add an AMD fTPM support feature

On Mon, Aug 26, 2019 at 02:40:19AM +0900, Seunghun Han wrote:
> I'm Seunghun Han and work at the Affiliated Institute of ETRI. I got an AMD
> system which had a Ryzen Threadripper 1950X and MSI mainboard, and I had
> a problem with AMD's fTPM. My machine showed an error message below, and
> the fTPM didn't work because of it.
> 
> [    5.732084] tpm_crb MSFT0101:00: can't request region for resource
>                [mem 0x79b4f000-0x79b4ffff]
> [    5.732089] tpm_crb: probe of MSFT0101:00 failed with error -16
> 
> When I saw the iomem areas and found two TPM CRB regions were in the ACPI
> NVS area.  The iomem regions are below.
> 
> 79a39000-79b6afff : ACPI Non-volatile Storage
>   79b4b000-79b4bfff : MSFT0101:00
>   79b4f000-79b4ffff : MSFT0101:00
> 
> After analyzing this issue, I found out that a busy bit was set to the ACPI
> NVS area, and the current Linux kernel allowed nothing to be assigned in
> it. I also found that the kernel couldn't calculate the sizes of command
> and response buffers correctly when the TPM regions were two or more.
> 
> To support AMD's fTPM, I removed the busy bit from the ACPI NVS area
> so that AMD's fTPM regions could be assigned in it. I also fixed the bug
> that did not calculate the sizes of command and response buffer correctly.
> 
> Signed-off-by: Seunghun Han <kkamagui@...il.com>

You need to split this into multiple patches e.g. if you think you've
fixed a bug, please write a patch with just the bug fix and nothing
else.

For further information, read the section three of

https://www.kernel.org/doc/html/latest/process/submitting-patches.html

I'd also recommend to check out the earlier discussion on ACPI NVS:

https://lore.kernel.org/linux-integrity/BCA04D5D9A3B764C9B7405BBA4D4A3C035EF7BC7@ALPMBAPA12.e2k.ad.ge.com/

/Jarkko