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Subject: Re: [RFC PATCH v4 01/13] iommu: Introduce dirty log tracking
 framework
To:     Keqian Zhu <zhukeqian1@huawei.com>, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org,
        Robin Murphy <robin.murphy@arm.com>,
        Will Deacon <will@kernel.org>, Joerg Roedel <joro@8bytes.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        Yi Sun <yi.y.sun@linux.intel.com>,
        Tian Kevin <kevin.tian@intel.com>
References: <20210507102211.8836-1-zhukeqian1@huawei.com>
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 <f47e90c6-f3c4-b28f-a810-e03afe79e62d@linux.intel.com>
 <60182a35-e151-7150-3708-4e58dd8e78da@huawei.com>
From:   Lu Baolu <baolu.lu@linux.intel.com>
Message-ID: <36cc7267-6aa3-db54-b08c-c2dfc0bbacb6@linux.intel.com>
Date:   Wed, 12 May 2021 11:20:18 +0800
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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?

Best regards,
baolu