Calgary anyway, pass 'iommu=calgary' on the kernel command line.
If unsure, say Y.
+config AMD_IOMMU
+ bool "AMD IOMMU support"
+ select SWIOTLB
+ depends on X86_64 && PCI && ACPI
+ help
+ With this option you can enable support for AMD IOMMU hardware in
+ your system. An IOMMU is a hardware component which provides
+ remapping of DMA memory accesses from devices. With an AMD IOMMU you
+ can isolate the the DMA memory of different devices and protect the
+ system from misbehaving device drivers or hardware.
+
+ You can find out if your system has an AMD IOMMU if you look into
+ your BIOS for an option to enable it or if you have an IVRS ACPI
+ table.
+
# need this always selected by IOMMU for the VIA workaround
config SWIOTLB
bool