> It’s also a bit misleading to characterize cloud providers as building on libvirt
Libvirt provides lifetime management for KVM virtual machines, including orchestration of live migration, setting up SELinux to ensure isolation between QEMU processes and cgroups to limit resource utilization, creating network interfaces and bridging them to host networking, and more. Any cloud provider that uses Openstack+KVM relies on Libvirt for all these tasks.