From: Keqian Zhu <zhukeqian1@huawei.com>
To: Yi Sun <yi.y.sun@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
jiangkunkun@huawei.com, Catalin Marinas <catalin.marinas@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
Cornelia Huck <cohuck@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>,
Kirti Wankhede <kwankhede@nvidia.com>,
linux-kernel@vger.kernel.org, lushenming@huawei.com,
iommu@lists.linux-foundation.org,
James Morse <james.morse@arm.com>, Marc Zyngier <maz@kernel.org>,
wanghaibin.wang@huawei.com, Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 04/11] iommu/arm-smmu-v3: Split block descriptor when start dirty log
Date: Tue, 16 Mar 2021 19:39:47 +0800 [thread overview]
Message-ID: <84cef87c-af82-8564-fc23-654042448d05@huawei.com> (raw)
In-Reply-To: <20210316091751.GN28580@yi.y.sun>
Hi Yi,
On 2021/3/16 17:17, Yi Sun wrote:
> On 21-03-10 17:06:07, Keqian Zhu wrote:
>> From: jiangkunkun <jiangkunkun@huawei.com>
>>
>> Block descriptor is not a proper granule for dirty log tracking.
>> Take an extreme example, if DMA writes one byte, under 1G mapping,
>> the dirty amount reported to userspace is 1G, but under 4K mapping,
>> the dirty amount is just 4K.
>>
>> This adds a new interface named start_dirty_log in iommu layer and
>> arm smmuv3 implements it, which splits block descriptor to an span
>> of page descriptors. Other types of IOMMU will perform architecture
>> specific actions to start dirty log.
>>
>> To allow code reuse, the split_block operation is realized as an
>> iommu_ops too. We flush all iotlbs after the whole procedure is
>> completed to ease the pressure of iommu, as we will hanle a huge
>> range of mapping in general.
>>
>> Spliting block does not simultaneously work with other pgtable ops,
>> as the only designed user is vfio, which always hold a lock, so race
>> condition is not considered in the pgtable ops.
>>
>> Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
>> Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
>> ---
>>
>> changelog:
>>
>> v2:
>> - Change the return type of split_block(). size_t -> int.
>> - Change commit message to properly describe race condition. (Robin)
>> - Change commit message to properly describe the need of split block.
>> - Add a new interface named start_dirty_log(). (Sun Yi)
>> - Change commit message to explain the realtionship of split_block() and start_dirty_log().
>>
>> ---
>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 52 +++++++++
>> drivers/iommu/io-pgtable-arm.c | 122 ++++++++++++++++++++
>> drivers/iommu/iommu.c | 48 ++++++++
>> include/linux/io-pgtable.h | 2 +
>> include/linux/iommu.h | 24 ++++
>> 5 files changed, 248 insertions(+)
>>
> Could you please split iommu common interface to a separate patch?
> This may make review and comments easier.
Yup, good suggestion.
>
> IMHO, I think the start/stop interfaces could be merged into one, e.g:
> int iommu_domain_set_hwdbm(struct iommu_domain *domain, bool enable,
> unsigned long iova, size_t size,
> int prot);
Looks good, this reduces some code. but I have a concern that this causes loss of flexibility,
as we must pass same arguments when start|stop dirty log. What's your opinion about this?
>
> Same comments to patch 5.
OK. Thanks.
>
> BRs,
> Yi Sun
>
>> --
>> 2.19.1
> .
Thanks,
Keqian
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next prev parent reply other threads:[~2021-03-16 11:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 9:06 [PATCH v2 00/11] vfio/iommu_type1: Implement dirty log tracking based on smmuv3 HTTU Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 01/11] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 02/11] iommu/arm-smmu-v3: Enable HTTU for stage1 with io-pgtable mapping Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 03/11] iommu/arm-smmu-v3: Add feature detection for BBML Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 04/11] iommu/arm-smmu-v3: Split block descriptor when start dirty log Keqian Zhu
2021-03-16 9:17 ` Yi Sun
2021-03-16 11:39 ` Keqian Zhu [this message]
2021-03-17 3:06 ` Yi Sun
2021-03-10 9:06 ` [PATCH v2 05/11] iommu/arm-smmu-v3: Merge a span of page when stop " Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 06/11] iommu/arm-smmu-v3: Scan leaf TTD to sync hardware " Keqian Zhu
2021-03-17 10:44 ` Yi Sun
2021-03-17 12:59 ` Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 07/11] iommu/arm-smmu-v3: Clear dirty log according to bitmap Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 08/11] iommu/arm-smmu-v3: Add HWDBM device feature reporting Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 09/11] vfio/iommu_type1: Add HWDBM status maintanance Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 10/11] vfio/iommu_type1: Optimize dirty bitmap population based on iommu HWDBM Keqian Zhu
2021-03-10 9:06 ` [PATCH v2 11/11] vfio/iommu_type1: Add support for manual dirty log clear Keqian Zhu
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