CONFIG_IBMVIO is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_IBMVIO (not configurable)

modulename: vio.ko

configname: CONFIG_IBMVIO

Linux/PowerPC Kernel Configuration
└─>Platform support
└─>IBMVIO
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
source code:
arch/powerpc/platforms/pseries/vio.c