Libvirt/QEMU guest

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This article covers libvirt and its creation of a virtual machine (VM) for use under the soft-emulation mode QEMU hypervisor Type-2, notably using virsh command.

The virsh command and its configuration toward the creation of an strict-emulation-mode virtual machine that an QEMU-capable operating system to be installed on.

Installation

Note
Use QEMU to install app-emulation/qemu and Libvirt to install app-emulation/libvirt. Once installed, return to this guide.

Verify system is capable of being a virtualization host.

root #virt-host-validate

  QEMU: Checking for hardware virtualization                                 : PASS
  QEMU: Checking if device /dev/kvm exists                                   : PASS
  QEMU: Checking if device /dev/kvm is accessible                            : PASS
  QEMU: Checking if device /dev/vhost-net exists                             : PASS
  QEMU: Checking if device /dev/net/tun exists                               : PASS
  QEMU: Checking for cgroup 'cpu' controller support                         : PASS
  QEMU: Checking for cgroup 'cpuacct' controller support                     : PASS
  QEMU: Checking for cgroup 'cpuset' controller support                      : PASS
  QEMU: Checking for cgroup 'memory' controller support                      : PASS
  QEMU: Checking for cgroup 'devices' controller support                     : PASS
  QEMU: Checking for cgroup 'blkio' controller support                       : PASS
  QEMU: Checking for device assignment IOMMU support                         : PASS
  QEMU: Checking if IOMMU is enabled by kernel                               : PASS
  QEMU: Checking for secure guest support                                    : WARN (Unknown if this platform has Secure Guest support)
    CH: Checking for hardware virtualization                                 : PASS
    CH: Checking if device /dev/kvm exists                                   : PASS
    CH: Checking if device /dev/kvm is accessible                            : PASS

Usage

List virtual machines (domains)

root #virsh list --all

 Id   Name                  State
-------------------------------------
 1    gentoo                running

Creating a virtual machine

Note
app-emulation/virt-manager includes virt-installer. Therefore, with only app-emulation/libvirt the VM xml must be created first, then either imported with virsh edit /path/to/vm.xml or virsh define /path/to/vm.xml

Sample VM for Gentoo below. Note, view wiki code for full xml, as below does not view correctly...

FILE /etc/libvirt/qemu/gentoo-vm.xml

<domain type='kvm'>
	<seclabel type='dynamic' model='selinux'>
		<baselabel>system_u:system_r:svirt_t:s0</baselabel>
	</seclabel>
	<name>gentoo</name>
	<uuid>XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX</uuid>
	<title>Gentoo VM</title>
	<description>Gentoo Description Here</description>
	<features>
		<acpi/>
		<smm state='on'/>
	</features>
	<os>
		<type arch='x86_64' machine='pc-q35-3.0'>hvm</type>
		<loader readonly='yes' secure='yes' type='pflash'>/usr/share/edk2-ovmf/OVMF_CODE.fd</loader>
		<nvram template='/usr/share/edk2-ovmf/OVMF_VARS.fd'>/var/lib/libvirt/qemu/nvram/media_VARS.fd</nvram>
		<boot dev='cdrom'/>
		<boot dev='hd'/>
	</os>
	<vcpu>2</vcpu>
	<memory unit='GiB'>6</memory>
	<clock sync="localtime"/>
	<devices>
		<emulator>/usr/bin/qemu-system-x86_64</emulator>
		<disk type='file' device='cdrom'>
			<driver name='qemu' type='raw' cache='none'/>
			'"`UNIQ--source-00000006-QINU`"'
			<target dev='sda' bus='sata' tray='open'/>
			<readonly/>
			<address type='drive' controller='0' bus='0' target='0' unit='0'/>
		</disk>
		<disk type='file' device='disk'>
			<driver name='qemu' type='qcow2'/>
			'"`UNIQ--source-00000008-QINU`"'
			<target dev='vda' bus='virtio'/>
		</disk>
		<interface type='bridge'>
			<mac address='XX:XX:XX:XX:XX:XX'/>
			'"`UNIQ--source-0000000A-QINU`"'
			<virtualport type='openvswitch'/>
			<model type='virtio'/>
		</interface>
		<serial type='pty'>
			<tartget port='0'/>
		</serial>		
		<console type='pty'>
			<tartget port='0'/>
		</console>
		<graphics type='vnc' port='-1' autoport='yes' passwd='password here' keymap='en-us'/>
	</devices>
</domain>

root #virsh define gentoo-vm.xml

Domain 'gentoo' defined from gentoo-vm.xml

root #virsh list --all

 Id   Name    State
------------------------
 -    gentoo   shut off

Starting a virtual machine

root #virsh start <vm-id>

Enabling autostart.

root #virsh autostart <vm-id>

Shutdown a virtual machine

Graceful shutdown, similar to pressing the power button on a physical machine.

root #virsh shutdown <vm-id>

Hard shutdown, similar to pulling the power cord on a physical machine.

root #virsh destroy <vm-id>