iommufd: Add an ioctl to query PA from IOVA for noiommu mode

To support no-IOMMU mode where userspace drivers perform unsafe DMA
using physical addresses, introduce a new API to retrieve the
physical address of a user-allocated DMA buffer that has been mapped to
an IOVA via IOMMU_IOAS_MAP. The mapping is backed by SW-only I/O page
tables maintained by the GENERIC_PT framework.

Link: https://patch.msgid.link/r/a60a601509688e8552c75e668deb548c93974a3b.1783360051.git.jacob.pan@linux.microsoft.com
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Co-developed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
Fixes: 2c6cf6ab1564 ("iommufd: Allow binding to a noiommu device")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Jacob Pan 2026-07-06 11:48:32 -07:00 • committed by Jason Gunthorpe
commit 60decab325
5 changed files with 163 additions and 0 deletions