Fast and Live Replacement of Hypervisors and Operating Systems

Background: 

Hypervisors and operating systems are becoming increasingly complex and must be often updated for applying security patches, bug fixes, and feature upgrades. However, updates to an operational hypervisor or OS can be highly disruptive. Before being updated, virtual machines (VMs) and applications running on a hypervisor must be either migrated away or shut down, resulting in downtime, performance loss, and network overhead.  

Technology Overview: 

We present a new technique, called HyperFresh, to transparently replace a hypervisor with a new updated instance without disrupting any running VMs. A thin shim layer, called the hyperplexor, performs live hypervisor replacement by remapping guest memory to a new updated hypervisor on the same machine.  

Advantages: 

• The hyperplexor leverages nested virtualization for hypervisor replacement while minimizing nesting overheads during normal execution.
• We present a prototype implementation of the hyperplexor on the KVM/QEMU platform that can perform live hypervisor replacement within 10ms.
• We also demonstrate how a hyperplexor-based approach can be used for sub-second relocation of containers for live OS replacement.