CONFIG_VIRT is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k

Virtual M68k Machine support

modulename: head.ko

configname: CONFIG_VIRT

Linux Kernel Configuration
└─>Virtual M68k Machine support
In linux kernel since version 5.2 (release Date: 2019-07-07)  
This options enable a pure virtual machine based on m68k,
VIRTIO MMIO devices and GOLDFISH interfaces (TTY, RTC, PIC).

source code:
arch/m68k/kernel/