Re: [PATCH] tpm: tpm_crb: Add an AMD fTPM support feature
From: Jarkko Sakkinen
Date: Mon Aug 26 2019 - 01:59:13 EST
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@xxxxxxxxx>
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
For further information, read the section three of
I'd also recommend to check out the earlier discussion on ACPI NVS: