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 E5843C55181 for ; Mon, 20 Apr 2020 20:46:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF34620857 for ; Mon, 20 Apr 2020 20:46:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726830AbgDTUqv (ORCPT ); Mon, 20 Apr 2020 16:46:51 -0400 Received: from mga03.intel.com ([134.134.136.65]:13069 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726764AbgDTUqv (ORCPT ); Mon, 20 Apr 2020 16:46:51 -0400 IronPort-SDR: Fmj1WMmP6Pi7ebs6pEo3e6FuJPLC3brLxWTLWGyQ1+5oGDCgF+eKj11YmmqZRK5Qju9aCHHll0 Q1VO730Xatqw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Apr 2020 13:46:50 -0700 IronPort-SDR: 7oF+MuTm6n9G/0eynM9XPNEelxXLoQZkuGe+VNrlW6X69eDGFP2U0th+G09c6YSCRwjT/grE62 x6JerV4RDdig== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,407,1580803200"; d="scan'208";a="245482558" Received: from rpirker-mobl2.ger.corp.intel.com (HELO localhost) ([10.252.46.184]) by fmsmga007.fm.intel.com with ESMTP; 20 Apr 2020 13:46:46 -0700 Date: Mon, 20 Apr 2020 23:46:41 +0300 From: Jarkko Sakkinen To: James Bottomley , zohar@linux.ibm.com 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: <20200420204641.GA14637@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> <20200417235527.GB85230@linux.intel.com> <1587168748.5867.2.camel@HansenPartnership.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1587168748.5867.2.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 Fri, Apr 17, 2020 at 05:12:28PM -0700, James Bottomley wrote: > On Sat, 2020-04-18 at 02:55 +0300, Jarkko Sakkinen wrote: > > 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? > > PCR writes would take longer meaning IMA initialization would become > slower. Does it matter? /Jarkko