iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED

For SMMUv3 a IOMMU_DOMAIN_NESTED is composed of a S2 iommu_domain acting
as the parent and a user provided STE fragment that defines the CD table
and related data with addresses translated by the S2 iommu_domain.

The kernel only permits userspace to control certain allowed bits of the
STE that are safe for user/guest control.

IOTLB maintenance is a bit subtle here, the S1 implicitly includes the S2
translation, but there is no way of knowing which S1 entries refer to a
range of S2.

For the IOTLB we follow ARM's guidance and issue a CMDQ_OP_TLBI_NH_ALL to
flush all ASIDs from the VMID after flushing the S2 on any change to the
S2.

The IOMMU_DOMAIN_NESTED can only be created from inside a VIOMMU as the
invalidation path relies on the VIOMMU to translate virtual stream ID used
in the invalidation commands for the CD table and ATS.

Link: https://patch.msgid.link/r/9-v4-9e99b76f3518+3a8-smmuv3_nesting_jgg@nvidia.com


Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Donald Dutile <ddutile@redhat.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>