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<h1>QEMU/KVM hypervisor driver</h1>
<ul id="toc"></ul>
<p>
The libvirt QEMU driver can manage any QEMU emulator from version 0.8.1
or later. It can also manage anything that provides the same QEMU command
line syntax and monitor interaction. This includes KVM, and Xenner.
</p>
<h2><a name="prereq">Deployment pre-requisites</a></h2>
<ul>
<li>
<strong>QEMU emulators</strong>: The driver will probe <code>/usr/bin</code>
for the presence of <code>qemu</code>, <code>qemu-system-x86_64</code>,
<code>qemu-system-mips</code>,<code>qemu-system-mipsel</code>,
<code>qemu-system-sparc</code>,<code>qemu-system-ppc</code>. The results
of this can be seen from the capabilities XML output.
</li>
<li>
<strong>KVM hypervisor</strong>: The driver will probe <code>/usr/bin</code>
for the presence of <code>qemu-kvm</code> and <code>/dev/kvm</code> device
node. If both are found, then KVM fullyvirtualized, hardware accelerated
guests will be available.
</li>
<li>
<strong>Xenner hypervisor</strong>: The driver will probe <code>/usr/bin</code>
for the presence of <code>xenner</code> and <code>/dev/kvm</code> device
node. If both are found, then Xen paravirtualized guests can be run using
the KVM hardware acceleration.
</li>
</ul>
<h2><a name="uris">Connections to QEMU driver</a></h2>
<p>
The libvirt QEMU driver is a multi-instance driver, providing a single
system wide privileged driver (the "system" instance), and per-user
unprivileged drivers (the "session" instance). The of the driver protocol
is "qemu". Some example conection URIs for the libvirt driver are:
</p>
<pre>
qemu:///session (local access to per-user instance)
qemu+unix:///session (local access to per-user instance)
qemu:///system (local access to system instance)
qemu+unix:///system (local access to system instance)
qemu://example.com/system (remote access, TLS/x509)
qemu+tcp://example.com/system (remote access, SASl/Kerberos)
qemu+ssh://root@example.com/system (remote access, SSH tunnelled)
</pre>
<h2><a name="imex">Import and export of libvirt domain XML configs</a></h2>
<p>The QEMU driver currently supports a single native
config format known as <code>qemu-argv</code>. The data for this format
is expected to be a single line first a list of environment variables,
then the QEMu binary name, finally followed by the QEMU command line
arguments</p>
<h3><a name="xmlimport">Converting from QEMU args to domain XML</a></h3>
<p>
The <code>virsh domxml-from-native</code> provides a way to convert an
existing set of QEMU args into a guest description using libvirt Domain XML
that can then be used by libvirt.
</p>
<pre>$ cat &gt; demo.args &lt;&lt;EOF
LC_ALL=C PATH=/bin HOME=/home/test USER=test \
LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 \
-nographic -monitor pty -no-acpi -boot c -hda \
/dev/HostVG/QEMUGuest1 -net none -serial none \
-parallel none -usb
EOF
$ virsh domxml-from-native qemu-argv demo.args
&lt;domain type='qemu'&gt;
&lt;uuid&gt;00000000-0000-0000-0000-000000000000&lt;/uuid&gt;
&lt;memory&gt;219136&lt;/memory&gt;
&lt;currentMemory&gt;219136&lt;/currentMemory&gt;
&lt;vcpu&gt;1&lt;/vcpu&gt;
&lt;os&gt;
&lt;type arch='i686' machine='pc'&gt;hvm&lt;/type&gt;
&lt;boot dev='hd'/&gt;
&lt;/os&gt;
&lt;clock offset='utc'/&gt;
&lt;on_poweroff&gt;destroy&lt;/on_poweroff&gt;
&lt;on_reboot&gt;restart&lt;/on_reboot&gt;
&lt;on_crash&gt;destroy&lt;/on_crash&gt;
&lt;devices&gt;
&lt;emulator&gt;/usr/bin/qemu&lt;/emulator&gt;
&lt;disk type='block' device='disk'&gt;
&lt;source dev='/dev/HostVG/QEMUGuest1'/&gt;
&lt;target dev='hda' bus='ide'/&gt;
&lt;/disk&gt;
&lt;/devices&gt;
&lt;/domain&gt;
</pre>
<p>NB, don't include the literral \ in the args, put everything on one line</p>
<h3><a name="xmlexport">Converting from domain XML to QEMU args</a></h3>
<p>
The <code>virsh domxml-to-native</code> provides a way to convert a
guest description using libvirt Domain XML, into a set of QEMU args
that can be run manually.
</p>
<pre>$ cat &gt; demo.xml &lt;&lt;EOF
&lt;domain type='qemu'&gt;
&lt;name&gt;QEMUGuest1&lt;/name&gt;
&lt;uuid&gt;c7a5fdbd-edaf-9455-926a-d65c16db1809&lt;/uuid&gt;
&lt;memory&gt;219200&lt;/memory&gt;
&lt;currentMemory&gt;219200&lt;/currentMemory&gt;
&lt;vcpu&gt;1&lt;/vcpu&gt;
&lt;os&gt;
&lt;type arch='i686' machine='pc'&gt;hvm&lt;/type&gt;
&lt;boot dev='hd'/&gt;
&lt;/os&gt;
&lt;clock offset='utc'/&gt;
&lt;on_poweroff&gt;destroy&lt;/on_poweroff&gt;
&lt;on_reboot&gt;restart&lt;/on_reboot&gt;
&lt;on_crash&gt;destroy&lt;/on_crash&gt;
&lt;devices&gt;
&lt;emulator&gt;/usr/bin/qemu&lt;/emulator&gt;
&lt;disk type='block' device='disk'&gt;
&lt;source dev='/dev/HostVG/QEMUGuest1'/&gt;
&lt;target dev='hda' bus='ide'/&gt;
&lt;/disk&gt;
&lt;/devices&gt;
&lt;/domain&gt;
EOF
$ virsh domxml-to-native qemu-argv demo.xml
LC_ALL=C PATH=/usr/bin:/bin HOME=/home/test \
USER=test LOGNAME=test /usr/bin/qemu -S -M pc \
-no-kqemu -m 214 -smp 1 -name QEMUGuest1 -nographic \
-monitor pty -no-acpi -boot c -drive \
file=/dev/HostVG/QEMUGuest1,if=ide,index=0 -net none \
-serial none -parallel none -usb
</pre>
<h2><a name="xmlconfig">Example domain XML config</a></h2>
<h3>QEMU emulated guest on x86_64</h3>
<pre>&lt;domain type='qemu'&gt;
&lt;name&gt;QEmu-fedora-i686&lt;/name&gt;
&lt;uuid&gt;c7a5fdbd-cdaf-9455-926a-d65c16db1809&lt;/uuid&gt;
&lt;memory&gt;219200&lt;/memory&gt;
&lt;currentMemory&gt;219200&lt;/currentMemory&gt;
&lt;vcpu&gt;2&lt;/vcpu&gt;
&lt;os&gt;
&lt;type arch='i686' machine='pc'&gt;hvm&lt;/type&gt;
&lt;boot dev='cdrom'/&gt;
&lt;/os&gt;
&lt;devices&gt;
&lt;emulator&gt;/usr/bin/qemu-system-x86_64&lt;/emulator&gt;
&lt;disk type='file' device='cdrom'&gt;
&lt;source file='/home/user/boot.iso'/&gt;
&lt;target dev='hdc'/&gt;
&lt;readonly/&gt;
&lt;/disk&gt;
&lt;disk type='file' device='disk'&gt;
&lt;source file='/home/user/fedora.img'/&gt;
&lt;target dev='hda'/&gt;
&lt;/disk&gt;
&lt;interface type='network'&gt;
&lt;source network='default'/&gt;
&lt;/interface&gt;
&lt;graphics type='vnc' port='-1'/&gt;
&lt;/devices&gt;
&lt;/domain&gt;</pre>
<h3>KVM hardware accelerated guest on i686</h3>
<pre>&lt;domain type='kvm'&gt;
&lt;name&gt;demo2&lt;/name&gt;
&lt;uuid&gt;4dea24b3-1d52-d8f3-2516-782e98a23fa0&lt;/uuid&gt;
&lt;memory&gt;131072&lt;/memory&gt;
&lt;vcpu&gt;1&lt;/vcpu&gt;
&lt;os&gt;
&lt;type arch="i686"&gt;hvm&lt;/type&gt;
&lt;/os&gt;
&lt;clock sync="localtime"/&gt;
&lt;devices&gt;
&lt;emulator&gt;/usr/bin/qemu-kvm&lt;/emulator&gt;
&lt;disk type='file' device='disk'&gt;
&lt;source file='/var/lib/libvirt/images/demo2.img'/&gt;
&lt;target dev='hda'/&gt;
&lt;/disk&gt;
&lt;interface type='network'&gt;
&lt;source network='default'/&gt;
&lt;mac address='24:42:53:21:52:45'/&gt;
&lt;/interface&gt;
&lt;graphics type='vnc' port='-1' keymap='de'/&gt;
&lt;/devices&gt;
&lt;/domain&gt;</pre>
<h3>Xen paravirtualized guests with hardware acceleration</h3>
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