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From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Safford, David (GE Global Research, US)" <david.safford@ge.com>
Cc: Matthew Garrett <mjg59@google.com>,
	"linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"jarkko.sakkinen@linux.intel.com"
	<jarkko.sakkinen@linux.intel.com>,
	"Wiseman, Monty (GE Global Research, US)" <monty.wiseman@ge.com>
Subject: Re: [PATCH] tpm_crb - workaround broken ACPI tables
Date: Fri, 12 Jul 2019 12:06:56 -0300
Message-ID: <20190712150656.GF27512@ziepe.ca> (raw)
In-Reply-To: <BCA04D5D9A3B764C9B7405BBA4D4A3C035EF7E2A@ALPMBAPA12.e2k.ad.ge.com>

On Fri, Jul 12, 2019 at 12:41:58PM +0000, Safford, David (GE Global Research, US) wrote:
> 
> > The issue is that the CRB region is mapped into a region marked as ACPI NVS.
> > drivers/acpi/nvs.c claims this region and as a result a resource conflict is
> > generated. Since Windows is clearly fine with other drivers using ACPI NVS
> > regions, the correct fix involves figuring out a way to either share these
> > resources or allow tpm_crb to reclaim the region from the NVS driver. Note
> > that the NVS driver's behaviour is to save and restore NVS regions over
> > suspend/resume, so simply forcibly allocating the resource will result in two
> > separate codepaths touching the region on resume - this seems like a bad
> > outcome. 

I wonder if the CRB in the nvs actually needs to be save/restored in
AMD's implementation?

Sounds like the answer is to have TPM CRB somehow detect NVS and
acquire the resource from it, while somehow sequencing suspend/resume
properly.

Jason

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 12:29 Safford, David (GE Global Research, US)
2019-07-11 14:10 ` Jarkko Sakkinen
2019-07-11 14:58 ` Jason Gunthorpe
2019-07-11 16:44   ` Safford, David (GE Global Research, US)
2019-07-11 18:50     ` Jason Gunthorpe
2019-07-11 19:31       ` Safford, David (GE Global Research, US)
2019-07-11 20:33         ` Matthew Garrett
2019-07-12 12:41           ` Safford, David (GE Global Research, US)
2019-07-12 15:06             ` Jason Gunthorpe [this message]
2019-07-12 15:48               ` Jarkko Sakkinen
2019-07-12 18:24             ` Matthew Garrett
2019-07-12 19:05               ` Safford, David (GE Global Research, US)
2019-07-12 20:36                 ` Matthew Garrett
2019-07-14 19:28                   ` Safford, David (GE Global Research, US)
2019-07-14 23:48                     ` Matthew Garrett
2019-07-15 19:44                       ` Matthew Garrett
2019-07-11 19:16 ` Jarkko Sakkinen

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