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=-0.8 required=3.0 tests=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 3094CC38A2E for ; Fri, 17 Apr 2020 23:56:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0636222282 for ; Fri, 17 Apr 2020 23:56:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726639AbgDQXzq (ORCPT ); Fri, 17 Apr 2020 19:55:46 -0400 Received: from mga18.intel.com ([134.134.136.126]:11627 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726619AbgDQXza (ORCPT ); Fri, 17 Apr 2020 19:55:30 -0400 IronPort-SDR: YGV7UFjQpCvqc3+ZDqUhhHSW45SZo9mg3znXiYG2qkl2sduxpRgr5BjfmwKAzaOnGU78qsQnDm 0SknHrML0D/A== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Apr 2020 16:55:29 -0700 IronPort-SDR: K+5T/j6lCyL3btQnzW68O2Iqs4TXn3eFAnpZCr8tKO1QjUM1aCD0CU6tWHhCETRxgaDTvIhNe9 0PnAPM3mpUNw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,395,1580803200"; d="scan'208";a="272580943" Received: from zhiwang1-mobl5.ger.corp.intel.com (HELO localhost) ([10.252.42.90]) by orsmga002.jf.intel.com with ESMTP; 17 Apr 2020 16:55:27 -0700 Date: Sat, 18 Apr 2020 02:55:27 +0300 From: Jarkko Sakkinen To: James Bottomley Cc: Omar Sandoval , Peter Huewe , Jason Gunthorpe , linux-integrity@vger.kernel.org Subject: Re: [PATCH] tpm_tis: work around status register bug in STMicroelectronics TPM Message-ID: <20200417235527.GB85230@linux.intel.com> References: <6c55d7c1fb84e5bf2ace9f05ec816ef67bd873e1.1586990595.git.osandov@fb.com> <1586994699.3931.18.camel@HansenPartnership.com> <20200416001605.GA673482@vader> <20200416002442.GB673482@vader> <1587060171.15329.7.camel@HansenPartnership.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1587060171.15329.7.camel@HansenPartnership.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Thu, Apr 16, 2020 at 11:02:51AM -0700, James Bottomley wrote: > On Wed, 2020-04-15 at 17:24 -0700, Omar Sandoval wrote: > > On Wed, Apr 15, 2020 at 05:16:05PM -0700, Omar Sandoval wrote: > > > On Wed, Apr 15, 2020 at 04:51:39PM -0700, James Bottomley wrote: > > > > On Wed, 2020-04-15 at 15:45 -0700, Omar Sandoval wrote: > > > > > From: Omar Sandoval > > > > > > > > > > We've encountered a particular model of STMicroelectronics TPM > > > > > that transiently returns a bad value in the status register. > > > > > This causes the kernel to believe that the TPM is ready to > > > > > receive a command when it actually isn't, which in turn causes > > > > > the send to time out in get_burstcount(). In testing, reading > > > > > the status register one extra time convinces the TPM to return > > > > > a valid value. > > > > > > > > Interesting, I've got a very early upgradeable nuvoton that seems > > > > to be behaving like this. > > > > > > I'll attach the userspace reproducer I used to figure this out. I'd > > > be interested to see if it times out on your TPM, too. Note that it > > > bangs on /dev/mem and assumes that the MMIO address is 0xfed40000. > > > That seems to be the hard-coded address for x86 in the kernel, but > > > just to be safe you might want to check `grep MSFT0101 > > > /proc/iomem`. > > > > Forgot to attach it, of course... > > > Thanks! You facebook guys run with interesting kernel options ... I > eventually had to disable CONFIG_STRICT_DEVMEM and rebuild my kernel to > get it to run. > > However, the bad news is that this isn't my problem, it seems to be > more timeout related I get the same symptoms: logs full of > > [14570.626594] tpm tpm0: tpm_try_transmit: tpm_send: error -62 > > and the TPM won't recover until the box is reset. To get my TPM to be > usable, I have to fiddle our default timeouts like this: > > --- a/drivers/char/tpm/tpm.h > +++ b/drivers/char/tpm/tpm.h > @@ -41,8 +41,8 @@ enum tpm_timeout { > TPM_TIMEOUT_RETRY = 100, /* msecs */ > TPM_TIMEOUT_RANGE_US = 300, /* usecs */ > TPM_TIMEOUT_POLL = 1, /* msecs */ > - TPM_TIMEOUT_USECS_MIN = 100, /* usecs */ > - TPM_TIMEOUT_USECS_MAX = 500 /* usecs */ > + TPM_TIMEOUT_USECS_MIN = 750, /* usecs */ > + TPM_TIMEOUT_USECS_MAX = 1000, /* usecs */ > }; > > But I think the problem is unique to my nuvoton because there haven't > been any other reports of problems like this ... and with these > timeouts my system functions normally in spite of me being a heavy TPM > user. What downsides there would be to increase these a bit? /Jarkko