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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 8533FC433DB for ; Fri, 15 Jan 2021 09:24:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 58FA423128 for ; Fri, 15 Jan 2021 09:24:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729083AbhAOJYe (ORCPT ); Fri, 15 Jan 2021 04:24:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:39432 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727204AbhAOJYb (ORCPT ); Fri, 15 Jan 2021 04:24:31 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id AC61A2339D; Fri, 15 Jan 2021 09:23:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610702631; bh=VCDpaZeUdppA614VVCSLc4aWw7dTZlkr+EHOCN3aUfQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aEdo1JA6/YfMV06tEfWDZpY8hbvb8EAbWe2pBi5L8Dw6h2GNDMjqCaxpLExYEJbSk /QtmoEtSr+OhlsIdR9oxDk3jz3Sg/cUI855MqtuZFmOdmc7tYK0IkNg+Hnd8J8KzhA FDkKnAyJv4z3diOOEDgyIP4EJIW8bcM4wpdgd7bR2h+gKlGxECRHkHY9VD1GiQmS8O FM88DYAUdKkI/qQl3jhWSUjoOI6dOPL3xX9b8KsAwFIl2D04v5cfDUgz4LeGchbc80 W5H6J9i1GRgSr/UaWYUW+fOW/x6RjgQN1kxXsQTbE5mUi7My1sa8d8nY2iBLPX0diq YYpqtz80ilwOw== Date: Fri, 15 Jan 2021 11:23:46 +0200 From: Jarkko Sakkinen To: Tianjia Zhang Cc: Peter Huewe , Jason Gunthorpe , linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, Jia Zhang Subject: Re: [PATCH] tpm/tpm_tis: Fix variable reset during IRQ probing Message-ID: References: <20210113120021.59045-1-tianjia.zhang@linux.alibaba.com> <44c35c27-0cd4-e451-1b9c-d6fe48e58e51@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44c35c27-0cd4-e451-1b9c-d6fe48e58e51@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 14, 2021 at 12:12:16PM +0800, Tianjia Zhang wrote: > > > 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. TPM_INT_ENABLE is cleared on reset [*]. [*] Section 5.9.1 https://trustedcomputinggroup.org/resource/pc-client-work-group-pc-client-specific-tpm-interface-specification-tis/ /Jarkko