From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E954C001DC for ; Mon, 31 Jul 2023 11:07:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231672AbjGaLHp (ORCPT ); Mon, 31 Jul 2023 07:07:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230212AbjGaLHo (ORCPT ); Mon, 31 Jul 2023 07:07:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F8C71BF; Mon, 31 Jul 2023 04:07:44 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D10FC6104B; Mon, 31 Jul 2023 11:07:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6745EC433C7; Mon, 31 Jul 2023 11:07:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690801663; bh=RV8Rk8epBSDHGl4CjLo2RB50HeXG/xuM7WBwj6ffrfg=; h=Date:Cc:Subject:From:To:References:In-Reply-To:From; b=hnQj3Y89tF3k+OzGkCF13kZ7RTEH+3Ve6nekpXyfQ8I12hXlUTh7joL2PooaC3Eq7 jmEK0Jman9bikOnW6zmcvrjYPz9Dx48cDMAu9Rv+0HhTpZtpGkdKA1fB0NI+IiQr13 59RKH/Y6JJvx5HG3rWzGE3KBJkaiMRdYLTew3L2ZbjYjNFcMaZ8pVW6tuPKdSU8QW4 HXOXccFy1tW1ILsqNQeXvlwY1Svb+E4wVrNQhSgwy3xUN11bziFqS/CcmrfSEGvB3l 25qfp5D9GNAIjFoQYEPUw5CzqMOzPwhMbVWdRam/9fCDetqzjws856YVm0PPDLtYKp +ZAcDBAGrru7g== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 31 Jul 2023 11:07:39 +0000 Message-Id: Cc: , , , , , , , Subject: Re: [PATCH 1/1] tpm: disable hwrng for fTPM on some AMD designs From: "Jarkko Sakkinen" To: "Daniil Stas" X-Mailer: aerc 0.14.0 References: <20230214201955.7461-2-mario.limonciello@amd.com> <20230727183805.69c36d6e@g14> <20230728231810.48370d44@g14> <20230731132837.64690d7b@g14> In-Reply-To: <20230731132837.64690d7b@g14> Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Mon Jul 31, 2023 at 10:28 AM UTC, Daniil Stas wrote: > On Mon, 31 Jul 2023 10:14:05 +0000 > "Jarkko Sakkinen" wrote: > > > On Fri Jul 28, 2023 at 8:18 PM UTC, Daniil Stas wrote: > > > On Fri, 28 Jul 2023 19:30:18 +0000 > > > "Jarkko Sakkinen" wrote: > > > =20 > > > > On Thu Jul 27, 2023 at 3:38 PM UTC, Daniil Stas wrote: =20 > > [...] =20 > > > >=20 > > > > This is needs a bit more elaboration in order to be comprehended. > > > >=20 > > > > Do you mean by "stutter" unexpected delays and when do they > > > > happen? > > > >=20 > > > > BR, Jarkko =20 > > > > > > Yes, unexpected delays. They just happen randomly. > > > You can google "AMD fTPM stuttering", there are a lot of examples. > > > Here is one: https://www.youtube.com/watch?v=3DTYnRL-x6DVI =20 > >=20 > > What if you make tpm_amd_is_rng_defective() to unconditonally return > > true? Does this make the problem dissappear, or not? > >=20 > > BR, Jarkko > > I already tried compiling kernel without CONFIG_HW_RANDOM_TPM enabled, > which does the same. > Yes, it removes the issue. Thank you, just wanted sanity check that I exactly know what is going on. BR, Jarkko