1. A computer program product for providing interruptions to guests of a computing environment, said computer program product comprising: a computer readable medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: based on executing a guest Modify PCI Functions Control (MPFC) instruction register interruptions operation that includes a function handle of an adapter, specifying a location in memory of a guest adapter interruption bit vector (AIBV), the guest AIBV being an AIBV of a guest array of one or more AIBVs, and a location in memory of a guest adapter interruption summary bit (AISB) identifying the adapter; receiving, by a component of the computing environment from the adapter, a request for interruption, the component of the computing environment having a host forwarding AISB array, the host forwarding AISB array having an AISB for each adapter available to the host that the host assigns to a guest; based on the received request, setting an indicator in the guest AIBV indicating an event from the adapter, and setting the host forwarding AISB array indicating an indicator is set in the guest AIBV; scanning the host forwarding AISB array for set host AISB indicators and determining whether the request for interruption is targeted to a guest; based on determining the request for interruption is targeted to the guest, determining one or more guest AISBs corresponding to the set AISBs of said host forwarding AISB array; and setting said determined one or more guest AISBs.