A processing unit includes a processor core that implements a physical function that supports multiple virtual functions. The processing unit includes a bus interface that supports communication between an external bus and the physical and virtual functions implemented using the processor core. During a reset of the processing unit, power is interrupted to the processor core power to the bus interface is maintained. The bus interface responds to requests for the physical and virtual functions received over the external bus concurrently with the power interruption. The bus interface responds based on state information associated with the virtual function. Power is restored to the processor core in response to the reinitialization of the GPU. The bus interface stops responding to requests for the physical and virtual functions received over the bus interface in response to restoring the power to the processor core and forwards requests received over the external bus from the bus interface to the processor core.