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Date: Mon, 19 Feb 2024 20:17:42 +0000
Cc: "Ross Philipson" <ross.philipson@oracle.com>, "Peter Huewe"
 <peterhuewe@gmx.de>
Subject: Re: [PATCH 2/3] tpm: ensure tpm is in known state at startup
From: "Jarkko Sakkinen" <jarkko@kernel.org>
To: "Daniel P. Smith" <dpsmith@apertussolutions.com>, "Jason Gunthorpe"
 <jgg@ziepe.ca>, <linux-integrity@vger.kernel.org>,
 <linux-kernel@vger.kernel.org>
Message-Id: <CZ9BYSWZVHLI.27ICPVJMGNHIM@seitikki>
References: <20240131170824.6183-1-dpsmith@apertussolutions.com>
 <20240131170824.6183-3-dpsmith@apertussolutions.com>
 <CYU3H17QGBR0.37HWK14BDMGCD@suppilovahvero>
 <2dd76ebf-b25d-447f-8abe-30e3423c4cdb@apertussolutions.com>
In-Reply-To: <2dd76ebf-b25d-447f-8abe-30e3423c4cdb@apertussolutions.com>

On Mon Feb 19, 2024 at 7:17 PM UTC, Daniel P. Smith wrote:
> On 2/1/24 17:33, Jarkko Sakkinen wrote:
> > On Wed Jan 31, 2024 at 7:08 PM EET, Daniel P. Smith wrote:
> >> When tis core initializes, it assumes all localities are closed. There
> >         ~~~~~~~~
> >         tpm_tis_core
> >=20
> >> are cases when this may not be the case. This commit addresses this by
> >> ensuring all localities are closed before initializing begins.
> >=20
> > Remove the last sentence and replace with this paragraph:
> >=20
> > "Address this by ensuring all the localities are closed in the beginnin=
g
> > of tpm_tis_core_init(). There are environments, like Intel TXT, which
> > may leave a locality open. Close all localities to start from a known
> > state."
>
> okay.
>
> > BTW, why we should motivated to take this patch anyway?
>
> Without this change, in this scenario the driver is unnecessarily=20
> thrashing the TPM with locality requests/relinquishes pairs for which=20
> will never take effect and that the TPM must do state change tracking.=20
> While I am confident that TPM chips are resilient to such abuse, I do=20
> not think it would be good form to knowingly allow such behavior to occur=
.

This would a factor better motivation part for the commit. I can=20
buy this argument instead the one right now, thanks :-)

BR, Jarkko