From: Lu Baolu <baolu.lu@linux.intel.com>
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>
Cc: baolu.lu@linux.intel.com,
Alex Williamson <alex.williamson@redhat.com>,
Kirti Wankhede <kwankhede@nvidia.com>,
Cornelia Huck <cohuck@redhat.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
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
Date: Tue, 11 May 2021 11:12:07 +0800 [thread overview]
Message-ID: <f47e90c6-f3c4-b28f-a810-e03afe79e62d@linux.intel.com> (raw)
In-Reply-To: <a8df289a-47c2-c193-cd6f-8415f68b900f@huawei.com>
Hi Keqian,
On 5/10/21 7:07 PM, Keqian Zhu wrote:
>>>> I suppose this interface is to ask the vendor IOMMU driver to check
>>>> whether each device/iommu in the domain supports dirty bit tracking.
>>>> But what will happen if new devices with different tracking capability
>>>> are added afterward?
>>> Yep, this is considered in the vfio part. We will query again after attaching or
>>> detaching devices from the domain. When the domain becomes capable, we enable
>>> dirty log for it. When it becomes not capable, we disable dirty log for it.
>> If that's the case, why not putting this logic in the iommu subsystem so
>> that it doesn't need to be duplicate in different upper layers?
>>
>> For example, add something like dirty_page_trackable in the struct of
>> iommu_domain and ask the vendor iommu driver to update it once any
>> device is added/removed to/from the domain. It's also better to disallow
> If we do it, the upper layer still needs to query the capability from domain and switch
> dirty log tracking for it. Or do you mean the domain can switch dirty log tracking automatically
> when its capability change? If so, I think we're lack of some flexibility. The upper layer
> may have it's own policy, such as only enable dirty log tracking when all domains are capable,
> and disable dirty log tracking when just one domain is not capable.
I may not get you.
Assume that dirty_page_trackable is an attribution of an iommu_domain.
This attribution might be changed once a new device (with different
capability) added or removed. So it should be updated every time a new
device is attached or detached. This work could be done by the vendor
iommu driver on the path of dev_attach/dev_detach callback.
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.
>
>> any domain attach/detach once the dirty page tracking is on.
> Yep, this can greatly simplify our code logic, but I don't know whether our maintainers
> agree that, as they may think that IOMMU dirty logging should not change original domain
> behaviors.
The maintainer owns the last word, but we need to work out a generic and
self-contained API set.
Best regards,
baolu
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next prev parent reply other threads:[~2021-05-11 10:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-07 10:21 [RFC PATCH v4 00/13] iommu/smmuv3: Implement hardware dirty log tracking Keqian Zhu
2021-05-07 10:21 ` [RFC PATCH v4 01/13] iommu: Introduce dirty log tracking framework Keqian Zhu
2021-05-08 3:46 ` Lu Baolu
2021-05-08 7:35 ` Keqian Zhu
2021-05-10 1:08 ` Lu Baolu
2021-05-10 11:07 ` Keqian Zhu
2021-05-11 3:12 ` Lu Baolu [this message]
2021-05-11 7:40 ` Keqian Zhu
2021-05-12 3:20 ` Lu Baolu
2021-05-12 8:44 ` Keqian Zhu
2021-05-12 11:36 ` Lu Baolu
2021-05-13 10:58 ` Keqian Zhu
2021-05-13 12:02 ` Lu Baolu
2021-05-14 2:30 ` Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 02/13] iommu/io-pgtable-arm: Add quirk ARM_HD and ARM_BBMLx Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 03/13] iommu/io-pgtable-arm: Add and realize split_block ops Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 04/13] iommu/io-pgtable-arm: Add and realize merge_page ops Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 05/13] iommu/io-pgtable-arm: Add and realize sync_dirty_log ops Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 06/13] iommu/io-pgtable-arm: Add and realize clear_dirty_log ops Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 07/13] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 08/13] iommu/arm-smmu-v3: Enable HTTU for stage1 with io-pgtable mapping Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 09/13] iommu/arm-smmu-v3: Add feature detection for BBML Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 10/13] iommu/arm-smmu-v3: Realize switch_dirty_log iommu ops Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 11/13] iommu/arm-smmu-v3: Realize sync_dirty_log " Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 12/13] iommu/arm-smmu-v3: Realize clear_dirty_log " Keqian Zhu
2021-05-07 10:22 ` [RFC PATCH v4 13/13] iommu/arm-smmu-v3: Realize support_dirty_log " Keqian Zhu
2021-05-17 8:46 ` [RFC PATCH v4 00/13] iommu/smmuv3: Implement hardware dirty log tracking Keqian Zhu
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