iommu/amd: Fix geometry.aperture_end for V2 tables

The AMD IOMMU documentation seems pretty clear that the V2 table follows
the normal CPU expectation of sign extension. This is shown in

  Figure 25: AMD64 Long Mode 4-Kbyte Page Address Translation

Where bits Sign-Extend [63:57] == [56]. This is typical for x86 which
would have three regions in the page table: lower, non-canonical, upper.

The manual describes that the V1 table does not sign extend in section
2.2.4 Sharing AMD64 Processor and IOMMU Page Tables GPA-to-SPA

Further, Vasant has checked this and indicates the HW has an addtional
behavior that the manual does not yet describe. The AMDv2 table does not
have the sign extended behavior when attached to PASID 0, which may
explain why this has gone unnoticed.

The iommu domain geometry does not directly support sign extended page
tables. The driver should report only one of the lower/upper spaces. Solve
this by removing the top VA bit from the geometry to use only the lower
space.

This will also make the iommu_domain work consistently on all PASID 0 and
PASID != 1.

Adjust dma_max_address() to remove the top VA bit. It now returns:

5 Level:
  Before 0x1ffffffffffffff
  After  0x0ffffffffffffff
4 Level:
  Before 0xffffffffffff
  After  0x7fffffffffff

Fixes: 11c439a1 ("iommu/amd/pgtbl_v2: Fix domain max address")
Link: https://lore.kernel.org/all/8858d4d6-d360-4ef0-935c-bfd13ea54f42@amd.com/


Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/0-v2-0615cc99b88a+1ce-amdv2_geo_jgg@nvidia.com


Signed-off-by: Will Deacon <will@kernel.org>