$ cat /etc/modprobe.d/qemu-system-x86.conf
options kvm_intel nested=1

$ cat /sys/module/kvm_intel/parameters/nested
Y

# echo "Number of processors that support KVM: $(grep -Ec "(vmx|svm)" /proc/cpuinfo)"
Number of processors that support KVM: 2

# lscpu | grep "Virtualization|Hypervisor"
Virtualization:        VT-x
Hypervisor vendor:     KVM
Virtualization type:   full

# lsmod | grep -i kvm
kvm_intel             170181  0
kvm                   554609  1 kvm_intel
irqbypass              13503  1 kvm

# virt-install --name=Nested-Arch --vcpus=1 --ram=512 --os-type=linux --os-variant=virtio26 --nographics --description "Arch Linux inside CentOS inside Ubuntu (Nesting)" --network bridge=virbr0,model=virtio --disk path=/var/lib/libvirt/images/guest.img,size=32 --cdrom=/root/Downloads/archlinux-2016.09.03-dual.iso --extra-args="console=tty0 console=ttyS0,115200n8 serial"
ERROR    Host does not support any virtualization options

# virt-install --prompt
WARNING  --prompt mode is no longer supported.
ERROR    Host does not support any virtualization options