A change of virtual topology configuration

A method for a configuration change of a topology of a plurality of guest processors (guest CPUs) of a guest configuration a host computer system divided into logical partitions comprising host processors (CPU host), the method being characterized by: a guest processor of the guest configuration which seeks (2001) an instruction to perform function topology defined by a computer architecture, the instruction to perform function topology field opcode that specifies the instruction to perform function topology comprising and a record field specifying a general register; execute the instruction to perform topology function, the execution comprising: obtaining a function control field FC from the general register specified; responding to FC having a first value or a second value specifying a request for a change of polarization, ie, a request to switch to assign evenly or unevenly resources physical treatment to guests processors, requesting change of polarization specified configuration topology guests processors guest configuration; respond to change requested specified polarization is accepted, changing the topology of the guest processors of the guest configuration according to the specified polarization change; You respond to the requested topology change is in progress, setting (2005) a first condition code value indicating a topology change initiated; respond to the requested topology change being rejected, setting (2007) a second condition code value indicating that the topology change is rejected; respond to changing topology requested is rejected, establish a code value RC reason in the register; responding to FC having a third value specifying a request for a status check topology change, set a condition code value indicating whether the topology change report is pending; and complete the execution of the instruction.