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 7B2DEC433ED for ; Thu, 13 May 2021 10:58:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 489A76143E for ; Thu, 13 May 2021 10:58:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232251AbhEMK7s (ORCPT ); Thu, 13 May 2021 06:59:48 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:5106 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232902AbhEMK7S (ORCPT ); Thu, 13 May 2021 06:59:18 -0400 Received: from dggeml712-chm.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4FgpV05v16zYhMv; Thu, 13 May 2021 18:55:36 +0800 (CST) Received: from dggpemm000003.china.huawei.com (7.185.36.128) by dggeml712-chm.china.huawei.com (10.3.17.123) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Thu, 13 May 2021 18:58:05 +0800 Received: from [10.174.187.224] (10.174.187.224) by dggpemm000003.china.huawei.com (7.185.36.128) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 13 May 2021 18:58:04 +0800 Subject: Re: [RFC PATCH v4 01/13] iommu: Introduce dirty log tracking framework To: Lu Baolu , , , , 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> <7fb678c7-509b-dbb5-d533-32c5ce2a0476@linux.intel.com> CC: Alex Williamson , Kirti Wankhede , Cornelia Huck , Jonathan Cameron , , , , From: Keqian Zhu Message-ID: Date: Thu, 13 May 2021 18:58:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <7fb678c7-509b-dbb5-d533-32c5ce2a0476@linux.intel.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.187.224] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm000003.china.huawei.com (7.185.36.128) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/5/12 19:36, Lu Baolu wrote: > 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. Hi Baolu, Right, if the "detach|attach" interfaces and "dirty tracking" interfaces can be called concurrently, a lock in iommu_domain_support_dirty_log() is still not enough. I will add another note for the dirty tracking interfaces. Do you have other suggestions? I will accelerate the progress, so I plan to send out v5 next week. Thanks, Keqian