Patent ID: 8898666

Claim:
A virtual machine system comprising: a memory including an execution state storage region for storing execution state information on an execution state of a processor; a first processor and a second processor each connected to the memory and provided with a low privileged mode and a high privileged mode higher than the low privileged mode; one or more operating systems running in the low privileged mode on a processor; a hypervisor, running in the high privileged mode on the first processor, that causes the first processor to perform processing for switching the operating system by saving and restoring execution state information in the execution state storage region, and provides the second processor with restoration notification based on the execution state information saved in the execution state storage region; and a restoration program, running in the low privileged mode on the second processor, that causes the second processor to restore the execution state information stored in the execution state storage region to the execution state information of the second processor upon receipt by the second processor of the restoration notification, wherein the execution state storage region includes a first execution state storage region accessible by the first processor in the high privileged mode and not accessible by the first processor and by the second processor in the low privileged mode; and a second execution state storage region accessible by the second processor in the low privileged mode, the hypervisor causes the first processor to save and restore the execution state information using the first execution state storage region and, when a processor change condition for executing a currently suspended operating system on the second processor is satisfied, writes the execution state information saved in the first execution state storage region for the currently suspended operating system into the second execution state storage region, and the restoration program causes the second processor to restore the execution state information stored in the second execution state storage region to the execution state information of the second processor.