[PATCH v6 13/25] iommufd: Add mmap interface

[Baolu Lu]

On 6/14/2025 3:14 PM, Nicolin Chen wrote:
> For vIOMMU passing through HW resources to user space (VMs), allowing a VM
> to control the passed through HW directly by accessing hardware registers,
> add an mmap infrastructure to map the physical MMIO pages to user space.
> 
> Maintain a maple tree per ictx as a translation table managing mmappable
> regions, from an allocated for-user mmap offset to an iommufd_mmap struct,
> where it stores the real PFN range for an io_remap_pfn_range call.
> 
> Keep track of the lifecycle of the mmappable region by taking refcount of
> its owner, so as to enforce user space to unmap the region first before it
> can destroy its owner object.
> 
> To allow an IOMMU driver to add and delete mmappable regions onto/from the
> maple tree, add iommufd_viommu_alloc/destroy_mmap helpers.
> 
> Reviewed-by: Kevin Tian<kevin.tian at intel.com>
> Signed-off-by: Nicolin Chen<nicolinc at nvidia.com>

Reviewed-by: Lu Baolu <baolu.lu at linux.intel.com>