RE: [RFC PATCH 0/3] vfio/migration: Support manual clear vfio dirty log

[Tian, Kevin]

> From: Kunkun Jiang
> Sent: Wednesday, March 10, 2021 5:41 PM
> 
> Hi all,
> 
> In the past, we clear dirty log immediately after sync dirty log to
> userspace. This may cause redundant dirty handling if userspace
> handles dirty log iteratively:
> 
> After vfio clears dirty log, new dirty log starts to generate. These
> new dirty log will be reported to userspace even if they are generated
> before userspace handles the same dirty page.
> 
> Since a new dirty log tracking method for vfio based on iommu hwdbm[1]
> has been introduced in the kernel and added a new capability named
> VFIO_DIRTY_LOG_MANUAL_CLEAR, we can eliminate some redundant dirty
> handling by supporting it.

Is there any performance data showing the benefit of this new method?

> 
> This series include patches as below:
> Patch 1:
> - updated the linux-headers/linux/vfio.h from kernel side
> 
> Patch 2:
> - introduced 'struct VFIODMARange' to describe a range of the given DMA
>   mapping and with respect to a VFIO_IOMMU_MAP_DMA operation
> 
> Patch 3:
> - implemented the operation to manual clear vfio dirty log, which can
>   eliminate some redundant dirty handling
> 
> Thanks,
> Kunkun Jiang
> 
> [1] https://lore.kernel.org/linux-iommu/20210310090614.26668-1-
> zhukeqian1@huawei.com/T/#mb168c9738ecd3d8794e2da14f970545d5820f
> 863
> 
> Zenghui Yu (3):
>   linux-headers: update against 5.12-rc2 and "vfio log clear" series
>   vfio: Maintain DMA mapping range for the container
>   vfio/migration: Support VFIO_IOMMU_DIRTY_PAGES_FLAG_CLEAR_BITMAP
> 
>  hw/vfio/common.c              | 207 ++++++++++++++++++++++++++++++++--
>  include/hw/vfio/vfio-common.h |  10 ++
>  linux-headers/linux/vfio.h    |  55 ++++++++-
>  3 files changed, 264 insertions(+), 8 deletions(-)
> 
> --
> 2.23.0
>