SmartOS is illumos distribution, designing as hypervisor os.
SmartOS has multiple separate mechanism, Zone and bhyve.
Vms run on bhyve, bhyve are separate by Zone, SmartOS use VMs separate by two layer.
And SmartOS uses bhyve for virtualization, user can choice difference hypervisor as Xen and KVM.
And SmartOS is developed by Sumsung, so project has continuity!