An interrupt signal is provided to a guest operating system. A bus connected module is operationally connected with a plurality of processors via a bus attachment device. The bus attachment device receives an interrupt signal from the bus connected module with an interrupt target ID identifying one of the processors assigned for use by the guest operating system as a target processor for handling the interrupt signal. The bus attachment device checks whether the target processor is running using a running indicator provided by an interrupt table entry stored in a memory operationally connected with the bus attachment device. If the target processor is running, the bus attachment device forwards the interrupt signal to the target processor for handling. A translation of the interrupt target ID to a logical processor ID of the target processor is used to address the target processor directly.