Virtualization of input/output devices in a logically partitioned data processing system

A hypervisor (management) layer synchronizes use of virtualized input/output (I/O) devices that may regularly be used by multiple partitions of a logically partitioned data processing system by making them callable by any system partition to the hypervisor layer. A partition makes a call to the hypervisor to reserve an I/O resource. If the I/O resource is presently allocated to another partition when a call is made to reserve the resource, the hypervisor rejects the request to reserve the device. If the resource is available, the hypervisor issues a command to the resource to service calls made from the reserving partition. After utilizing the resource as necessary, the reserving partition releases control over the I/O device and sends a notification to hypervisor that it has released the I/O device. Upon release, the I/O device will automatically be available for use by another partition via a call to the hypervisor.