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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3800EC433E7 for ; Sun, 18 Oct 2020 05:10:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EB32B20EDD for ; Sun, 18 Oct 2020 05:10:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725306AbgJRFKH (ORCPT ); Sun, 18 Oct 2020 01:10:07 -0400 Received: from mga18.intel.com ([134.134.136.126]:60823 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725294AbgJRFKH (ORCPT ); Sun, 18 Oct 2020 01:10:07 -0400 IronPort-SDR: ksWizRfLdH6eLpVObCaCcaxc+ysNqETvPd0R5v84OPb0gfpzb52jEl9Q/LjGJh3RWfpGlMDEyS Oa64m8BXn78A== X-IronPort-AV: E=McAfee;i="6000,8403,9777"; a="154655154" X-IronPort-AV: E=Sophos;i="5.77,388,1596524400"; d="scan'208";a="154655154" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Oct 2020 22:10:03 -0700 IronPort-SDR: LRMf8+x1dPYWf7ofXsiB7V27/FaKq4cUtt9ycbYsEYHGDInT5ZzAkbzjn7K0QF/iK2WuX9Ldqo LNAm/m1ZZY+Q== X-IronPort-AV: E=Sophos;i="5.77,388,1596524400"; d="scan'208";a="301053354" Received: from hebenstp-mobl3.ger.corp.intel.com (HELO localhost) ([10.252.54.12]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Oct 2020 22:09:56 -0700 Date: Sun, 18 Oct 2020 08:09:51 +0300 From: Jarkko Sakkinen To: Hao Wu Cc: James Bottomley , Nayna , peterhuewe@gmx.de, jgg@ziepe.ca, arnd@arndb.de, gregkh@linuxfoundation.org, Hamza Attak , why2jjj.linux@gmail.com, zohar@linux.vnet.ibm.com, linux-integrity@vger.kernel.org, Paul Menzel , Ken Goldman , Seungyeop Han , Shrihari Kalkar , Anish Jhaveri Subject: Re: [PATCH] Fix Atmel TPM crash caused by too frequent queries Message-ID: <20201018050951.GL68722@linux.intel.com> References: <20200930153715.GC52739@linux.intel.com> <95aafaa1e3037cb7b99ae0e76c02a419d366a407.camel@HansenPartnership.com> <20200930210956.GC65339@linux.intel.com> <6e7b54c268d25a86f8f969bcc01729eaadef6530.camel@HansenPartnership.com> <20201001015051.GA5971@linux.intel.com> <1aed1b0734435959d5e53b8a4b3c18558243e6b8.camel@HansenPartnership.com> <19de5527-2d56-6a07-3ce7-ba216b208090@linux.vnet.ibm.com> <38e165055bae62d4e97f702c05e3a76ccdeeac0f.camel@HansenPartnership.com> <20201001230426.GA26517@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Fri, Oct 16, 2020 at 11:11:37PM -0700, Hao Wu wrote: > > On Oct 1, 2020, at 4:04 PM, Jarkko Sakkinen wrote: > > > > On Thu, Oct 01, 2020 at 11:32:59AM -0700, James Bottomley wrote: > >> On Thu, 2020-10-01 at 14:15 -0400, Nayna wrote: > >>> On 10/1/20 12:53 AM, James Bottomley wrote: > >>>> On Thu, 2020-10-01 at 04:50 +0300, Jarkko Sakkinen wrote: > >>>>> On Wed, Sep 30, 2020 at 03:31:20PM -0700, James Bottomley wrote: > >>>>>> On Thu, 2020-10-01 at 00:09 +0300, Jarkko Sakkinen wrote: > >> [...] > >>>>>>> I also wonder if we could adjust the frequency dynamically. > >>>>>>> I.e. start with optimistic value and lower it until finding > >>>>>>> the sweet spot. > >>>>>> > >>>>>> The problem is the way this crashes: the TPM seems to be > >>>>>> unrecoverable. If it were recoverable without a hard reset of > >>>>>> the entire machine, we could certainly play around with it. I > >>>>>> can try alternative mechanisms to see if anything's viable, but > >>>>>> to all intents and purposes, it looks like my TPM simply stops > >>>>>> responding to the TIS interface. > >>>>> > >>>>> A quickly scraped idea probably with some holes in it but I was > >>>>> thinking something like > >>>>> > >>>>> 1. Initially set slow value for latency, this could be the > >>>>> original 15 ms. > >>>>> 2. Use this to read TPM_PT_VENDOR_STRING_*. > >>>>> 3. Lookup based vendor string from a fixup table a latency that > >>>>> works > >>>>> (the fallback latency could be the existing latency). > >>>> > >>>> Well, yes, that was sort of what I was thinking of doing for the > >>>> Atmel ... except I was thinking of using the TIS VID (16 byte > >>>> assigned vendor ID) which means we can get the information to set > >>>> the timeout before we have to do any TPM operations. > >>> > >>> I wonder if the timeout issue exists for all TPM commands for the > >>> same manufacturer. For example, does the ATMEL TPM also crash when > >>> extending PCRs ? > >>> > >>> In addition to defining a per TPM vendor based lookup table for > >>> timeout, would it be a good idea to also define a Kconfig/boot param > >>> option to allow timeout setting. This will enable to set the timeout > >>> based on the specific use. > >> > >> I don't think we need go that far (yet). The timing change has been in > >> upstream since: > >> > >> commit 424eaf910c329ab06ad03a527ef45dcf6a328f00 > >> Author: Nayna Jain > >> Date: Wed May 16 01:51:25 2018 -0400 > >> > >> tpm: reduce polling time to usecs for even finer granularity > >> > >> Which was in the released kernel 4.18: over two years ago. In all that > >> time we've discovered two problems: mine which looks to be an artifact > >> of an experimental upgrade process in a new nuvoton and the Atmel. > >> That means pretty much every other TPM simply works with the existing > >> timings > >> > >>> I was also thinking how will we decide the lookup table values for > >>> each vendor ? > >> > >> I wasn't thinking we would. I was thinking I'd do a simple exception > >> for the Atmel and nothing else. I don't think my Nuvoton is in any way > >> characteristic. Indeed my pluggable TPM rainbow bridge system works > >> just fine with a Nuvoton and the current timings. > >> > >> We can add additional exceptions if they actually turn up. > > > > I'd add a table and fallback. > > > > Hi folks, > > I want to follow up this a bit and check whether we reached a consensus > on how to fix the timeout issue for Atmel chip. > > Should we revert the changes or introduce the lookup table for chips. > > Is there anything I can help from Rubrik side. > > Thanks > Hao There is nothing to revert as the previous was not applied but I'm of course ready to review any new attempts. /Jarkko