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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 63627C433E0 for ; Thu, 14 Jan 2021 04:13:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16E5E238E4 for ; Thu, 14 Jan 2021 04:13:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727091AbhANENE (ORCPT ); Wed, 13 Jan 2021 23:13:04 -0500 Received: from out30-45.freemail.mail.aliyun.com ([115.124.30.45]:41688 "EHLO out30-45.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726013AbhANEND (ORCPT ); Wed, 13 Jan 2021 23:13:03 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R831e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=tianjia.zhang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0ULg9c1f_1610597536; Received: from B-455UMD6M-2027.local(mailfrom:tianjia.zhang@linux.alibaba.com fp:SMTPD_---0ULg9c1f_1610597536) by smtp.aliyun-inc.com(127.0.0.1); Thu, 14 Jan 2021 12:12:16 +0800 Subject: Re: [PATCH] tpm/tpm_tis: Fix variable reset during IRQ probing To: Jarkko Sakkinen Cc: Peter Huewe , Jason Gunthorpe , linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, Jia Zhang References: <20210113120021.59045-1-tianjia.zhang@linux.alibaba.com> From: Tianjia Zhang Message-ID: <44c35c27-0cd4-e451-1b9c-d6fe48e58e51@linux.alibaba.com> Date: Thu, 14 Jan 2021 12:12:16 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/14/21 10:51 AM, Jarkko Sakkinen wrote: > On Wed, Jan 13, 2021 at 08:00:21PM +0800, Tianjia Zhang wrote: >> In tpm_tis_core_init(), tpm2_probe() will be called first, this >> function will eventually call tpm_tis_send(), and then >> tpm_tis_probe_irq_single() will detect whether the interrupt is >> normal, mainly the installation interrupted, set `priv->irq_tested` >> to false. The logic will eventually be executed to tpm_tis_send() >> to trigger an interrupt. >> >> There is currently such a scenario, which will cause the IRQ probe >> code to never be executed, so that the TPM device is in polling >> mode: after setting irq_tested to false, an interrupt occurs >> between entering the ttpm_tis_send() function, and the interrupt >> will be first set irq_tested to true will cause the IRQ probe code >> to never be executed. > > Can you describe the scenario more detail? > The problematic scenario we encountered is like this. The following figure shows the execution flow of tpm_tis_core_init(). An interrupt occurred before the IRQ probe. This interrupt was caused by tpm2_probe(), but it was triggered before the IRQ probe was executed, and the interrupt handler would set irq_tested to true, so the IRQ probe code can never execute, that is, the code marked 2 in the figure will never happen. IRQ tpm_tis_core_init() tpm2_probe() tpm_tis_send() -----------+ | tpm_tis_probe_irq_single() | | devm_request_irq() | 1 priv->irq_tested = false | tpm_tis_gen_interrupt() | | tpm_tis_send() | irq_tested = true | <------------------+ if (priv->irq_tested) return tpm_tis_send_main() /* probe IRQ */ tpm_tis_send_main() --------+ | 2 chip->flags |= FLAG_IRQ <-------+ priv->irq_tested = true Best regards, Tianjia