x86/iommu: add map-reserved dom0-iommu option to map reserved memory ranges

x86/iommu: add map-reserved dom0-iommu option to map reserved memory ranges

Several people have reported hardware issues (malfunctioning USB
controllers) due to iommu page faults on Intel hardware. Those faults
are caused by missing RMRR (VTd) entries in the ACPI tables. Those can
be worked around on VTd hardware by manually adding RMRR entries on
the command line, this is however limited to Intel hardware and quite
cumbersome to do.

In order to solve those issues add a new dom0-iommu=map-reserved
option that identity maps all regions marked as reserved in the memory
map. Note that regions used by devices emulated by Xen (LAPIC, IO-APIC
or PCIe MCFG regions) are specifically avoided. Note that this option
is available to all Dom0 modes (as opposed to the inclusive option
which only works for PV Dom0).

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>