iommu: Generic support for RMRs during device release

iommu: Generic support for RMRs during device release

Generally an IOMMU driver should leave the translation as BLOCKED until the
translation entry is probed onto a struct device. When the struct device is
removed, the translation should be put back to BLOCKED.

Drivers that are able to work like this can set their release_domain to the
blocking domain, and the core code handles this work.

The exception is when the device has an IOMMU_RESV_DIRECT region, in which
case the OS should continuously allow translations for the given range. And
the core code generally prevents using a BLOCKED domain with this device.

Continue this logic for the device release and hoist some open coding from
drivers. If the device has dev->iommu->require_direct and the driver uses a
BLOCKED release_domain, override it to IDENTITY to preserve the semantics.

The only remaining required driver code for IOMMU_RESV_DIRECT should preset
an IDENTITY translation during early IOMMU startup for those devices.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>