On 21-03-10 17:06:07, Keqian Zhu wrote:

From: jiangkunkun <redacted>

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 <redacted>
Signed-off-by: Kunkun Jiang <redacted>
---

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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