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

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Message-ID: <20210317104429.GT28580@yi.y.sun>
Date:   Wed, 17 Mar 2021 18:44:29 +0800
From:   Yi Sun <yi.y.sun@...ux.intel.com>
To:     Keqian Zhu <zhukeqian1@...wei.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 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!

[...]

> 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
future extension, it may be required.

BRs,
Yi Sun