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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 461DEC2BB55 for ; Thu, 16 Apr 2020 17:08:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2AC402078E for ; Thu, 16 Apr 2020 17:08:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728557AbgDPRIO (ORCPT ); Thu, 16 Apr 2020 13:08:14 -0400 Received: from mga18.intel.com ([134.134.136.126]:40337 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727795AbgDPRIO (ORCPT ); Thu, 16 Apr 2020 13:08:14 -0400 IronPort-SDR: xlrGfs5XVN0s+7sgOsYcL/D8+1EEqMxkuVXdrFWJB1ER+LlIKlFy2HVKj6ImBH7N6iXaPMy+CX eNdmtret6xuw== 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; 16 Apr 2020 10:08:12 -0700 IronPort-SDR: 6UnbU5k+Zc3c+RQV0mPYlO5Udp34XmhLBQPWsV7sNAJC0OM5v4lB5biLwHWYo+B7OKynhNKi1H oPFoBLwIylBg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,391,1580803200"; d="scan'208";a="246046517" Received: from otazetdi-mobl.ccr.corp.intel.com (HELO localhost) ([10.249.42.128]) by fmsmga008.fm.intel.com with ESMTP; 16 Apr 2020 10:08:11 -0700 Date: Thu, 16 Apr 2020 20:08:10 +0300 From: Jarkko Sakkinen To: Omar Sandoval Cc: Peter Huewe , Jason Gunthorpe , linux-integrity@vger.kernel.org Subject: Re: [PATCH] tpm_tis: work around status register bug in STMicroelectronics TPM Message-ID: <20200416170810.GD199110@linux.intel.com> References: <6c55d7c1fb84e5bf2ace9f05ec816ef67bd873e1.1586990595.git.osandov@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6c55d7c1fb84e5bf2ace9f05ec816ef67bd873e1.1586990595.git.osandov@fb.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 Wed, Apr 15, 2020 at 03:45:22PM -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. > > Signed-off-by: Omar Sandoval So what is the bad value? /Jarkko