1. A method comprising: receiving, by a processing device executing, a hypervisor, a request pertaining to a multi-function device managed by the hypervisor from a guest operating system of a virtual machine, the multi-function device comprising a main function and a plurality of sub-functions, the request identifying an address within a configuration space associated with one of the plurality of sub-functions of the multi-function device: determining, by the hypervisor, the main function of the multi-function device in view of the address of the configuration space associated with the sub-function; accessing, by the hypervisor; a data structure associated with the main function to obtain an indicator of availability of the main function to the guest operating system; determining, by the hypervisor in view of the indicator of availability, whether the main function is available to the guest operating system; and responsive to determining that the main function is not available, rejecting, by the hypervisor, the request from the guest operating system to access the address within the configuration space associated with the sub-function.