iommufd: Add mmap interface

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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 physical address range for io_remap_pfn_range().

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.

Link: https://patch.msgid.link/r/9a888a326b12aa5fe940083eae1156304e210fe0.1752126748.git.nicolinc@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

...

This commit is contained in:

Nicolin Chen 2025-07-09 22:59:09 -07:00 • committed by Jason Gunthorpe

parent 20896914da

commit 56e9a0d8e5

4 changed files with 171 additions and 0 deletions

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52

drivers/iommu/iommufd/driver.c

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14

drivers/iommu/iommufd/iommufd_private.h

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63

drivers/iommu/iommufd/main.c

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42

include/linux/iommufd.h

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