intel_iommu: Introduce property "stale-tm" to control Transient Mapping (TM) field

intel_iommu: Introduce property "stale-tm" to control Transient Mapping (TM) field

VT-d spec removed Transient Mapping (TM) field from second-level page-tables
and treat the field as Reserved(0) since revision 3.2.

Changing the field as reserved(0) will break backward compatibility, so
introduce a property "stale-tm" to allow user to control the setting.

Use pc_compat_9_1 to handle the compatibility for machines before 9.2 which
allow guest to set the field. Starting from 9.2, this field is reserved(0)
by default to match spec. Of course, user can force it on command line.

This doesn't impact function of vIOMMU as there was no logic to emulate
Transient Mapping.

Suggested-by: Yi Liu <yi.l.liu@intel.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Message-Id: <20241028022514.806657-1-zhenzhong.duan@intel.com>
Reviewed-by: Clément Mathieu--Drif<clement.mathieu--drif@eviden.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>