https://lesitedefrancois.be/en/tags/libvirt/Recent content in Libvirt on Le Site de FrançoisHugo -- gohugo.ioen© 2026 Françoishttps://lesitedefrancois.be/en/security/kvm-qemu/Mon, 01 Jan 0001 00:00:00 +0000https://lesitedefrancois.be/en/security/kvm-qemu/<p><strong>KVM</strong> (Kernel-based Virtual Machine) and <strong>QEMU</strong> (Quick Emulator) solve different halves of the same problem and are almost always used together. <strong>KVM</strong> is a Linux kernel module that turns the kernel into a hypervisor: with <strong>Intel VT-x</strong> or <strong>AMD-V</strong>, guest CPUs run on real hardware at near-native speed and guest memory is managed through extended page tables. KVM has no device model of its own — no disk, network, or firmware emulation. <strong>QEMU</strong> supplies that in userspace (virtio, USB, VGA, ACPI) and controls KVM by issuing <strong>ioctl</strong> calls on <strong><code>/dev/kvm</code></strong> — creating VMs, mapping memory, running vCPUs via <code>KVM_RUN</code> — while <strong>QMP</strong> exposes external management over a Unix socket. <strong>libvirt</strong>, originally from Red Hat, sits above both: it translates <strong>domain XML</strong> into QEMU command lines and lifecycle operations. The stack is the default on Linux: <strong>RHEL</strong> ships <code>qemu-kvm</code>, <strong>OpenShift Virtualization</strong> runs <strong>KubeVirt</strong> (<code>virt-launcher</code> → libvirt → QEMU), and <strong>OpenShift Sandboxed Containers</strong> uses <strong>Kata Containers</strong> with the same hypervisor to isolate pods in micro-VMs.</p>