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Date: Wed, 22 May 2024 17:11:11 +0300
Message-Id: <D1G8FRJFBBAO.X8CAFK3K34VJ@kernel.org>
Cc: <keyrings@vger.kernel.org>, "Peter Huewe" <peterhuewe@gmx.de>, "Jason
 Gunthorpe" <jgg@ziepe.ca>, "Mimi Zohar" <zohar@linux.ibm.com>, "David
 Howells" <dhowells@redhat.com>, "Paul Moore" <paul@paul-moore.com>, "James
 Morris" <jmorris@namei.org>, "Serge E. Hallyn" <serge@hallyn.com>,
 <linux-kernel@vger.kernel.org>, <linux-security-module@vger.kernel.org>
Subject: Re: [PATCH 1/3] tpm: Disable TCG_TPM2_HMAC by default
From: "Jarkko Sakkinen" <jarkko@kernel.org>
To: "Vitor Soares" <ivitro@gmail.com>, "James Bottomley"
 <James.Bottomley@HansenPartnership.com>, <linux-integrity@vger.kernel.org>
References: <20240519235122.3380-1-jarkko@kernel.org>
 <20240519235122.3380-2-jarkko@kernel.org>
 <850862655008f84ef0b6ecd99750e8dc395304d1.camel@gmail.com>
 <D1F4V8NMSUNZ.2VCTEKHZZ0LB@kernel.org>
 <17dc838120b56ce342c34611596c7b46dcd9ab5a.camel@HansenPartnership.com>
 <2dd8d49516ec9c7cb8c1182b5b8537b1e82d7067.camel@gmail.com>
 <D1G5O2Z86E4W.2DHG4QZE2W2JG@kernel.org>
 <56e52200bd9ede6bcdcc907d24bd4a3e0dddd24f.camel@gmail.com>
In-Reply-To: <56e52200bd9ede6bcdcc907d24bd4a3e0dddd24f.camel@gmail.com>

On Wed May 22, 2024 at 4:17 PM EEST, Vitor Soares wrote:
> > 1. What is the aarch64 platform you are using?
>
> I was testing this on the Toradex Verdin iMX8MM SoM.
>
> > 2. What kind of TPM you are using and how is it connect?
>
> TPM device is the ATTPM20P connect through the SPI at speed of 36 MHz.
> The bus is shared with a CAN controller (MCP251xFD), so both mues work to=
gether.
>
> The dts looks like:
> tpm1: tpm@1 {
>         compatible =3D "atmel,attpm20p", "tcg,tpm_tis-spi";
>         interrupts-extended =3D <&gpio1 7 IRQ_TYPE_LEVEL_LOW>;
>         pinctrl-0 =3D <&pinctrl_can2_int>;
>         pinctrl-names =3D "default";
>         reg =3D <1>;
>         spi-max-frequency =3D <36000000>;
> };

Thank you, this exactly what I was looking for. Don't expect any
improvement to the situation before rc1 is out. It is better to
investigate the situation a bit first.

E.g. some people test with fTPM TEE so this was pretty essential
to know that it is a chip going through.

For tpm_crb we should actually disable HMAC at some point. It is
essentially a performance regression for it.

BR, Jarkko