On 21-03-10 17:06:07, Keqian Zhu wrote:
> From: jiangkunkun <jiangkun...@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 <zhukeqi...@huawei.com>
> Signed-off-by: Kunkun Jiang <jiangkun...@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.
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);
Same comments to patch 5.
BRs,
Yi Sun
> --
> 2.19.1
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