CONFIG_KVM_BOOK3S_64 is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

KVM support for PowerPC book3s_64 processors

modulename: kvm.ko

configname: CONFIG_KVM_BOOK3S_64

Linux Kernel Configuration
└─>KVM support for PowerPC book3s_64 processors
In linux kernel since version 2.6.33 (release Date: 2010-02-24)  
Support running unmodified book3s_64 and book3s_32 guest kernels
in virtual machines on book3s_64 host processors.

This module provides access to the hardware capabilities through
a character device node named /dev/kvm.

If unsure, say N.

source code: