iommu/amd: Add support for HTRangeIgnore feature

AMD IOMMU reserves the address range 0xfd00000000-0xffffffffff for
the hypertransport protocol (HT) and has special meaning. Hence devices
cannot use this address range for the DMA. However on some AMD platforms
this HT range is shifted to the very top of the address space and new
feature bit `HTRangeIgnore` is introduced. When this feature bit is on,
IOMMU treats the GPA access to the legacy HT range as regular GPA access.

Signed-off-by: Sairaj Kodilkar <sarunkod@amd.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20250317055020.25214-1-sarunkod@amd.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>