US 12,124,866 B2
Fast virtual machine resume at host upgrade
Michael Tsirkin, Westford, MA (US)
Assigned to Red Hat, Inc., Raleigh, NC (US)
Filed by Red Hat, Inc., Raleigh, NC (US)
Filed on Oct. 28, 2020, as Appl. No. 17/082,701.
Prior Publication US 2022/0129292 A1, Apr. 28, 2022
Int. Cl. G06F 9/455 (2018.01); G06F 11/14 (2006.01); G06F 11/20 (2006.01)
CPC G06F 9/45558 (2013.01) [G06F 11/1402 (2013.01); G06F 11/2017 (2013.01); G06F 2009/45575 (2013.01); G06F 2009/45583 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A system comprising:
at least one memory including a persistent storage;
at least one processor in communication with the at least one memory;
a virtual machine associated with a virtual machine memory; and
a hypervisor executing on the at least one processor, wherein the hypervisor is configured to:
map the virtual machine memory to the persistent storage prior to a restart of a host,
detect a request to restart the host as part of an upgrade to the host after an initial mapping between the virtual machine memory and the persistent storage,
in response to detecting the request to restart the host, synchronize the virtual machine memory by checking a flag for each page of the virtual machine memory that has changed after the initial mapping between the virtual machine memory and the persistent storage, and copying data to the persistent storage for each page of the virtual machine memory that has changed based at least upon the flag,
pause the virtual machine prior to the host restarting without stopping the virtual machine,
save a virtual machine state to the persistent storage subsequent to the virtual machine being paused,
restore the virtual machine state after the host restarts to upgrade the host, and
resume operation of the virtual machine in response to restoring the virtual machine state.