iommu/amd: Introduce gDomID-to-hDomID Mapping and handle parent domain invalidation

iommu/amd: Introduce gDomID-to-hDomID Mapping and handle parent domain invalidation

Each nested domain is assigned guest domain ID (gDomID), which guest OS
programs into guest Device Table Entry (gDTE). For each gDomID, the driver
assigns a corresponding host domain ID (hDomID), which will be programmed
into the host Device Table Entry (hDTE).

The hDomID is allocated during amd_iommu_alloc_domain_nested(),
and free during nested_domain_free(). The gDomID-to-hDomID mapping info
(struct guest_domain_mapping_info) is stored in a per-viommu xarray
(struct amd_iommu_viommu.gdomid_array), which is indexed by gDomID.

Note also that parent domain can be shared among struct iommufd_viommu.
Therefore, when hypervisor invalidates the nest parent domain, the AMD
IOMMU command INVALIDATE_IOMMU_PAGES must be issued for each hDomID in
the gdomid_array. This is handled by the iommu_flush_pages_v1_hdom_ids(),
where it iterates through struct protection_domain.viommu_list.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>