i have selected kmod-kvm-intel,kmod-kvm-x86 in menuconfig...
while i can't find any kvm module using:lsmod | grep kvm...
what's the matter?? 
Selected as "m" or as "x"?
"m" means build it
"x" means built it and include it in image
Is it installed? opkg list-installed | grep kmod-kvm
If you aren´t using it, why should it be loaded?
root@OpenWrt:~# opkg list-installed | grep kmod-kvm
kmod-kvm-intel - 4.14.162-1
kmod-kvm-x86 - 4.14.162-1
root@OpenWrt:~# lsmod | grep kvm
root@OpenWrt:~#
Answer?
Normally it makes only sense to keep a module loaded if there is really a use case...
But if you wanna load it without using it afterwards, try modprobe modulname or insmod /path/to/module
while input a command : qemu-system-x86_64 ... --enable-kvm
i can't still see any output after : lsmod | grep kvm??
help... 