Received-SPF: pass (google.com: domain of linux-kernel+bounces-184543-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Message-ID: <850862655008f84ef0b6ecd99750e8dc395304d1.camel@gmail.com>
Subject: Re: [PATCH 1/3] tpm: Disable TCG_TPM2_HMAC by default
From: Vitor Soares <ivitro@gmail.com>
To: Jarkko Sakkinen <jarkko@kernel.org>, linux-integrity@vger.kernel.org
Cc: keyrings@vger.kernel.org, James.Bottomley@HansenPartnership.com, 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
Date: Tue, 21 May 2024 08:03:24 +0100
In-Reply-To: <20240519235122.3380-2-jarkko@kernel.org>
References: <20240519235122.3380-1-jarkko@kernel.org>
	 <20240519235122.3380-2-jarkko@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.44.4-0ubuntu2 
Precedence: bulk
MIME-Version: 1.0

Hi Jarkko,

On Mon, 2024-05-20 at 02:51 +0300, Jarkko Sakkinen wrote:
> Causes performance drop in initialization so needs to be opt-in.
> Distributors are capable of opt-in enabling this. Could be also handled b=
y
> kernel-command line in the future.
>=20
> Reported-by: Vitor Soares <ivitro@gmail.com>
> Closes:
> https://lore.kernel.org/linux-integrity/bf67346ef623ff3c452c4f968b7d90091=
1e250c3.camel@gmail.com/#t
> Fixes: d2add27cf2b8 ("tpm: Add NULL primary creation")
> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> ---
> =C2=A0drivers/char/tpm/Kconfig | 2 +-
> =C2=A01 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index e63a6a17793c..db41301e63f2 100644
> --- a/drivers/char/tpm/Kconfig
> +++ b/drivers/char/tpm/Kconfig
> @@ -29,7 +29,7 @@ if TCG_TPM
> =C2=A0
> =C2=A0config TCG_TPM2_HMAC
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0bool "Use HMAC and encryp=
ted transactions on the TPM bus"
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0default y
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0default n
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0select CRYPTO_ECDH
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0select CRYPTO_LIB_AESCFB
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0select CRYPTO_LIB_SHA256

I did the test on my side, and with TCG_TPM2_HMAC set to "n" the time to pr=
obe
tpm_tis_spi driver has reduced to:
real    0m2.009s
user    0m0.001s
sys     0m0.019s

Thanks for your help.

Best regards,
Vitor Soares