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 982C3C433ED for ; Wed, 12 May 2021 11:37:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B1D6613D6 for ; Wed, 12 May 2021 11:37:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230216AbhELLiM (ORCPT ); Wed, 12 May 2021 07:38:12 -0400 Received: from mga05.intel.com ([192.55.52.43]:62179 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230197AbhELLiK (ORCPT ); Wed, 12 May 2021 07:38:10 -0400 IronPort-SDR: wcvoJX32daI6q1ZfruXwNm0/Bsxz9zU81Bru11aPneC5Ie+hW/KBRrsnUorWlaJOsXM9d1hRGf oYIBANA8/8Bw== X-IronPort-AV: E=McAfee;i="6200,9189,9981"; a="285185306" X-IronPort-AV: E=Sophos;i="5.82,293,1613462400"; d="scan'208";a="285185306" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 May 2021 04:37:01 -0700 IronPort-SDR: /H5FLzSrZq+cwNz0Azt92onxkumHrnfiBrY3Lf5zJuvazIodXgHxSAY4WCiCCFCq8gbo3W8m6h rUxD+mRhMjiA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,293,1613462400"; d="scan'208";a="622372334" Received: from allen-box.sh.intel.com (HELO [10.239.159.128]) ([10.239.159.128]) by fmsmga006.fm.intel.com with ESMTP; 12 May 2021 04:36:57 -0700 Cc: baolu.lu@linux.intel.com, Alex Williamson , Kirti Wankhede , Cornelia Huck , Jonathan Cameron , wanghaibin.wang@huawei.com, jiangkunkun@huawei.com, yuzenghui@huawei.com, lushenming@huawei.com Subject: Re: [RFC PATCH v4 01/13] iommu: Introduce dirty log tracking framework To: Keqian Zhu , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, Robin Murphy , Will Deacon , Joerg Roedel , Jean-Philippe Brucker , Yi Sun , Tian Kevin References: <20210507102211.8836-1-zhukeqian1@huawei.com> <20210507102211.8836-2-zhukeqian1@huawei.com> <18ac787a-179e-71f7-728b-c43feda80a16@huawei.com> <55fda826-9ab6-a3a0-b17e-a4d4879f00bc@linux.intel.com> <60182a35-e151-7150-3708-4e58dd8e78da@huawei.com> <36cc7267-6aa3-db54-b08c-c2dfc0bbacb6@linux.intel.com> From: Lu Baolu Message-ID: <7fb678c7-509b-dbb5-d533-32c5ce2a0476@linux.intel.com> Date: Wed, 12 May 2021 19:36:10 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 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 Hi keqian, On 5/12/21 4:44 PM, Keqian Zhu wrote: > > > On 2021/5/12 11:20, Lu Baolu wrote: >> On 5/11/21 3:40 PM, Keqian Zhu wrote: >>>> For upper layers, before starting page tracking, they check the >>>> dirty_page_trackable attribution of the domain and start it only it's >>>> capable. Once the page tracking is switched on the vendor iommu driver >>>> (or iommu core) should block further device attach/detach operations >>>> until page tracking is stopped. >>> But when a domain becomes capable after detaching a device, the upper layer >>> still needs to query it and enable dirty log for it... >>> >>> To make things coordinated, maybe the upper layer can register a notifier, >>> when the domain's capability change, the upper layer do not need to query, instead >>> they just need to realize a callback, and do their specific policy in the callback. >>> What do you think? >>> >> >> That might be an option. But why not checking domain's attribution every >> time a new tracking period is about to start? > Hi Baolu, > > I'll add an attribution in iommu_domain, and the vendor iommu driver will update > the attribution when attach/detach devices. > > The attribute should be protected by a lock, so the upper layer shouldn't access > the attribute directly. Then the iommu_domain_support_dirty_log() still should be > retained. Does this design looks good to you? Yes, that's what I was thinking of. But I am not sure whether it worth of a lock here. It seems not to be a valid behavior for upper layer to attach or detach any device while doing the dirty page tracking. Best regards, baolu