iommufd: Support a HWPT without an iommu driver for noiommu

Create just a little part of a real iommu driver, enough to
slot in under the dev_iommu_ops() and allow iommufd to call
domain_alloc_paging_flags() and fail everything else.

This allows explicitly creating a HWPT under an IOAS.

A new Kconfig option IOMMUFD_NOIOMMU is introduced to differentiate
from the VFIO group/container based noiommu mode.

Link: https://patch.msgid.link/r/8d1ad0b90db0381d4139eda5c126cc8d168d89f8.1783360051.git.jacob.pan@linux.microsoft.com
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
Fixes: 2c6cf6ab1564 ("iommufd: Allow binding to a noiommu device")
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

0 files changed, 0 insertions, 0 deletions