In the course of reading the response to v1 (patch 1 only) I realized that not only that patch needs further adjustment, but that also further changes are needed (and there's likely yet more amiss).
1: x86/IOMMU: mark IOMMU / intremap not in use when ACPI tables are missing 2: x86/APIC: avoid iommu_supports_x2apic() on error path 3: AMD/IOMMU: iommu_enable vs iommu_intremap Jan
