Xen is a type 1 hypervisor under the GPLv2 license. It allows to run multiple operating systems at once on the same hardware platform. Since version 4.4 Xen supports A20 SoCs, with the Cubietruck actually being used in the official Xen test farm.
Starting with version 4.10-rc1 more Allwinner SoCs are supported, including 64-bit SoCs like the A64 and H5. It has been briefly tested on the OrangePi Zero, Pine64 and OrangePi PC2 board. For more details on how to run Xen on Allwinner based boards refer to the Xen wiki.