CONFIG_VFIO_VIRQFD (not configurable)

modulename: vfio_virqfd.ko

configname: CONFIG_VFIO_VIRQFD

Linux Kernel Configuration
└─>Device Drivers
└─>VFIO_VIRQFD
In linux kernel since version 3.10 (release Date: 2013-06-30)  
source code:
drivers/vfio/
selects

CONFIG_EVENTFD

depends
CONFIG_EVENTFD
CONFIG_VFIO

is depended by
CONFIG_VFIO_PCI_CORE