linux-kernel - Re: [PATCH v2 06/11] iommu/arm-smmu-v3: Scan leaf TTD to sync hardware dirty log

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Date:   Wed, 17 Mar 2021 20:59:37 +0800
From:   Keqian Zhu <zhukeqian1@...wei.com>
To:     Yi Sun <yi.y.sun@...ux.intel.com>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux-foundation.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Robin Murphy <robin.murphy@....com>,
        "Will Deacon" <will@...nel.org>,
        Kirti Wankhede <kwankhede@...dia.com>,
        "Cornelia Huck" <cohuck@...hat.com>, Marc Zyngier <maz@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        <wanghaibin.wang@...wei.com>, <jiangkunkun@...wei.com>,
        <yuzenghui@...wei.com>, <lushenming@...wei.com>
Subject: Re: [PATCH v2 06/11] iommu/arm-smmu-v3: Scan leaf TTD to sync
 hardware dirty log

On 2021/3/17 18:44, Yi Sun wrote:
> On 21-03-10 17:06:09, Keqian Zhu wrote:
>> From: jiangkunkun <jiangkunkun@...wei.com>
>>
>> During dirty log tracking, user will try to retrieve dirty log from
>> iommu if it supports hardware dirty log.
>>
>> This adds a new interface named sync_dirty_log in iommu layer and
>> arm smmuv3 implements it, which scans leaf TTD and treats it's dirty
>> if it's writable (As we just enable HTTU for stage1, so check whether
>> AP[2] is not set).
>>
>> Co-developed-by: Keqian Zhu <zhukeqian1@...wei.com>
>> Signed-off-by: Kunkun Jiang <jiangkunkun@...wei.com>
>> ---
>>
>> changelog:
>>
>> v2:
>>  - Add new sanity check in arm_smmu_sync_dirty_log(). (smmu_domain->stage != ARM_SMMU_DOMAIN_S1)
>>  - Document the purpose of flush_iotlb in arm_smmu_sync_dirty_log(). (Robin)
>>  
>> ---
>>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 30 +++++++
>>  drivers/iommu/io-pgtable-arm.c              | 90 +++++++++++++++++++++
>>  drivers/iommu/iommu.c                       | 38 +++++++++
>>  include/linux/io-pgtable.h                  |  4 +
>>  include/linux/iommu.h                       | 18 +++++
>>  5 files changed, 180 insertions(+)
>>
> Please split iommu common interface out. Thanks!
Yes, I will do it in v3.

> 
> [...]
> 
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 2a10294b62a3..44dfb78f9050 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -2850,6 +2850,44 @@ int iommu_stop_dirty_log(struct iommu_domain *domain, unsigned long iova,
>>  }
>>  EXPORT_SYMBOL_GPL(iommu_stop_dirty_log);
>>  
>> +int iommu_sync_dirty_log(struct iommu_domain *domain, unsigned long iova,
>> +			 size_t size, unsigned long *bitmap,
>> +			 unsigned long base_iova, unsigned long bitmap_pgshift)
> 
> One open question: shall we add PASID as one parameter to make iommu
> know which address space to visit?
> 
> For live migration, the pasid should not be necessary. But considering
Sure, for live migration we just need to care about level/stage 2 mapping under nested mode.

> future extension, it may be required.
It sounds a good idea. I will consider this, thanks!

> 
> BRs,
> Yi Sun
> .
> 
Thanks,
Keqian