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,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 97174C433E0 for ; Thu, 18 Mar 2021 03:08:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D07D64E90 for ; Thu, 18 Mar 2021 03:08:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230495AbhCRDHr (ORCPT ); Wed, 17 Mar 2021 23:07:47 -0400 Received: from mga17.intel.com ([192.55.52.151]:37684 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229934AbhCRDHp (ORCPT ); Wed, 17 Mar 2021 23:07:45 -0400 IronPort-SDR: yKaHnaUzQnywe95yNEuQkdb/x5Chl9qpJUdr+k7I/SBFtDGmMl0bIBydA5v3kZvJHv+LrCxaet +mQF0f3SNEoA== X-IronPort-AV: E=McAfee;i="6000,8403,9926"; a="169509492" X-IronPort-AV: E=Sophos;i="5.81,257,1610438400"; d="scan'208";a="169509492" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2021 20:07:45 -0700 IronPort-SDR: To81mTiyNzacaGr5ZeEbxfATpWia2tmPKB2sFuzkB9r9yHyKe+V7SxCkeKvoOXKX4lQ4qQgQOP JadvHCF0TF7w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,257,1610438400"; d="scan'208";a="433651877" Received: from allen-box.sh.intel.com (HELO [10.239.159.128]) ([10.239.159.128]) by fmsmga004.fm.intel.com with ESMTP; 17 Mar 2021 20:07:43 -0700 Cc: baolu.lu@linux.intel.com, "Longpeng (Mike, Cloud Infrastructure Service Product Dept.)" , dwmw2@infradead.org, joro@8bytes.org, will@kernel.org, iommu@lists.linux-foundation.org, LKML , "Gonglei (Arei)" , chenjiashang@huawei.com Subject: =?UTF-8?Q?Re=3a_A_problem_of_Intel_IOMMU_hardware_=ef=bc=9f?= To: Alex Williamson References: <670baaf8-4ff8-4e84-4be3-030b95ab5a5e@huawei.com> <692186fd-42b8-4054-ead2-f6c6b1bf5b2d@linux.intel.com> <20210317091820.5f4ab69e@omen.home.shazbot.org> From: Lu Baolu Message-ID: <87a5f90a-d1ea-fe7a-2577-fdfdf25f8fd7@linux.intel.com> Date: Thu, 18 Mar 2021 10:58:30 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210317091820.5f4ab69e@omen.home.shazbot.org> 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 Hi Alex, On 3/17/21 11:18 PM, Alex Williamson wrote: >>> {MAP, 0x0, 0xc0000000}, --------------------------------- (b) >>> use GDB to pause at here, and then DMA read IOVA=0, >> IOVA 0 seems to be a special one. Have you verified with other addresses >> than IOVA 0? > It is??? That would be a problem. > No problem from hardware point of view as far as I can see. Just thought about software might handle it specially. Best regards, baolu