Enabling nested KVM support for a instack-virt-setup deployment.

The following bash snippet will enable nested KVM support in the host when deploying TripleO using instack-virt-setup.

This will work in AMD or Intel architectures.

#!/bin/bash
echo "Checking if nested KVM is enabled in the host."
ARCH=$(lscpu | grep Architecture | head -1 | awk '{print $2}')
if [[ $ARCH == 'x86_64' ]]; then
    ARCH_BRAND=intel
    KVM_STATUS_FILE=/sys/module/kvm_intel/parameters/nested
    ENABLE_NESTED_KVM=Y
else
    ARCH_BRAND=amd
    KVM_STATUS_FILE=/sys/module/kvm_amd/parameters/nested
    ENABLE_NESTED_KVM=1
fi
if [[ -f $KVM_STATUS_FILE ]]; then
    KVM_CURRENT_STATUS=$(head -n 1 $KVM_STATUS_FILE)
    if [[ "${KVM_CURRENT_STATUS^^}" -ne "${ENABLE_NESTED_KVM^^}" ]]; then
        echo "This host does not have nested KVM enabled, enabling."
        sudo rmmod kvm-$ARCH_BRAND
        sudo sh -c "echo 'options kvm-$ARCH_BRAND nested=$ENABLE_NESTED_KVM' >> /etc/modprobe.d/dist.conf"
        sudo modprobe kvm-$ARCH_BRAND
    else
        echo "Nested KVM support is already enabled."
    fi
else
    echo "$KVM_STATUS_FILE does not exist."
fi

By default nested virtualization with KVM is disabled in the host, so in order to run the overcloud-pingtest correctly we have two options. Either run the previous snippet on the host, or, when deploying the Compute node in a virtual machine add --libvirt-type qemu to the deployment command. Otherwise launching instances on the deployed overcloud will fail.

Here you have an example of the deployment command, fixing libvirt to qemu.

cd
openstack overcloud deploy \
--libvirt-type qemu \
--ntp-server pool.ntp.org \
--templates /home/stack/tripleo-heat-templates \
-e /home/stack/tripleo-heat-templates/overcloud-resource-registry-puppet.yaml \
-e /home/stack/tripleo-heat-templates/environments/puppet-pacemaker.yaml

Have a happy TripleO deployment!