CONFIG_KVM_440 is not available for the default architecture x86.
Result is shown for architecture powerpc
default or selected kernelversion does not have config value CONFIG_KVM_440.
Result is shown for kernelversion 6.5.1

KVM support for PowerPC 440 processors

modulename: kvm.ko
configname: CONFIG_KVM_440

Linux Kernel Configuration
└─> Virtualization
└─> KVM support for PowerPC 440 processors

In linux kernel since version 2.6.29 (release Date: 2009-03-23)  

Support running unmodified 440 guest kernels in virtual machines on
440 host processors.

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

If unsure, say N.

source code: