add_virtio_drivers_2

# chroot in
#cd /mnt
#chroot root bash

# set the version
#cat /etc/grub/grub.cnf
version=3.10.0-1127.19.1.el7.x86_64
# example: version=3.10.0-1062.1.2.el7.x86_64

# check for virtio drivers
lsinitrd /boot/initramfs-$version.img | grep virtio

# if not found, add them
cd /boot
dracut -f /boot/initramfs-$version.img $version --add-drivers "virtio virtio_pci virtio_blk virtio_net"

dracut --regenerate-all -f && grub2-mkconfig -o /boot/grub2/grub.cfg

# prove it worked
lsinitrd /boot/initramfs-$version.img | grep virtio

# leave the chroot
exit