1. A computing cloud comprising: a plurality of computing nodes connected into a cluster, each node having a Hypervisor with the highest privilege level, and a Virtual Machine Monitor (VMM) running with no higher privilege level than the Hypervisor, and Virtual Machines (VMs) running on a non-privileged level; each Virtual Machine having a Guest Operating System running within it; each node having a host operating system (HOS), each HOS having access to at least some hardware devices of the corresponding computing node under supervision of the Hypervisor; and the VMs of the corresponding node using the HOS of its node to access the hardware devices, wherein the Hypervisor processes all interrupts and exceptions and dispatches them to the HOS and VMMs, and wherein the Hypervisor is responsible for interrupt forwarding, for context switching between the HOS and the VMMs, and for resource scheduling.