Re: [PATCH V3 3/4] iommufd: Add IOMMU_IOAS_CHANGE_PROCESS

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Oct 07, 2024 at 10:13:22AM -0700, Steve Sistare wrote:
> Add an ioctl that updates all DMA mappings to reflect the current process,
> Change the mm and transfer locked memory accounting from old to current mm.
> This will be used for live update, allowing an old process to hand the
> iommufd device descriptor to a new process.  The new process calls the
> ioctl.
> 
> IOMMU_IOAS_CHANGE_PROCESS only supports DMA mappings created with
> IOMMU_IOAS_MAP_FILE, because the kernel metadata for such mappings does
> not depend on the userland VA of the pages (which is different in the new
> process).
> IOMMU_IOAS_CHANGE_PROCESS fails if other types of mappings are present.
> 
> This is a revised version of code originally provided by Jason.
> 
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  drivers/iommu/iommufd/io_pagetable.h    |   1 +
>  drivers/iommu/iommufd/ioas.c            | 142 ++++++++++++++++++++++++++++++++
>  drivers/iommu/iommufd/iommufd_private.h |   1 +
>  drivers/iommu/iommufd/main.c            |   2 +
>  include/uapi/linux/iommufd.h            |  23 ++++++
>  5 files changed, 169 insertions(+)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason