Re: [PATCH Kernel v23 4/8] vfio iommu: Add ioctl definition for dirty pages tracking

[Cornelia Huck <cohuck@redhat.com>]

On Wed, 20 May 2020 23:38:04 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:

> IOMMU container maintains a list of all pages pinned by vfio_pin_pages API.
> All pages pinned by vendor driver through this API should be considered as
> dirty during migration. When container consists of IOMMU capable device and
> all pages are pinned and mapped, then all pages are marked dirty.
> Added support to start/stop dirtied pages tracking and to get bitmap of all
> dirtied pages for requested IO virtual address range.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Reviewed-by: Neo Jia <cjia@nvidia.com>
> ---
>  include/uapi/linux/vfio.h | 56 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 56 insertions(+)

(...)

> +/**
> + * VFIO_IOMMU_DIRTY_PAGES - _IOWR(VFIO_TYPE, VFIO_BASE + 17,
> + *                                     struct vfio_iommu_type1_dirty_bitmap)
> + * IOCTL is used for dirty pages logging.
> + * Caller should set flag depending on which operation to perform, details as
> + * below:
> + *
> + * Calling the IOCTL with VFIO_IOMMU_DIRTY_PAGES_FLAG_START flag set, instructs
> + * the IOMMU driver to log pages that are dirtied or potentially dirtied by
> + * device; designed to be used when a migration is in progress. Dirty pages are

s/device/the device/

> + * loggeded until logging is disabled by user application by calling the IOCTL

s/loggeded/logged/

> + * with VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP flag.
> + *
> + * Calling the IOCTL with VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP flag set, instructs
> + * the IOMMU driver to stop logging dirtied pages.
> + *
> + * Calling the IOCTL with VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP flag set
> + * returns the dirty pages bitmap for IOMMU container for a given IOVA range.
> + * User must specify the IOVA range and the pgsize through the structure

s/User/The user/

> + * vfio_iommu_type1_dirty_bitmap_get in the data[] portion. This interface
> + * supports to get bitmap of smallest supported pgsize only and can be modified

s/to get/getting a/

s/smallest/the smallest/

> + * in future to get bitmap of specified pgsize. The user must provide a zeroed

"a bitmap of any specified supported pgsize" ?

> + * memory area for the bitmap memory and specify its size in bitmap.size.
> + * One bit is used to represent one page consecutively starting from iova
> + * offset. The user should provide page size in bitmap.pgsize field. A bit set
> + * in the bitmap indicates that the page at that offset from iova is dirty.
> + * The caller must set argsz to a value including the size of structure
> + * vfio_iommu_type1_dirty_bitmap_get, but excluding the size of the actual
> + * bitmap. If dirty pages logging is not enabled, an error will be returned.

(...)

With the nits fixed,
Reviewed-by: Cornelia Huck <cohuck@redhat.com>