Add XML config for resource partitions

Allow VMs to be placed into resource groups using the
following syntax

  <resource>
    <partition>/virtualmachines/production</partition>
  </resource>

A resource cgroup will be backed by some hypervisor specific
functionality, such as cgroups with KVM/LXC.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

docs/formatdomain.html.in

@@ -716,6 +716,35 @@
     </dl>
 
 
+    <h3><a name="resPartition">Resource partitioning</a></h3>
+
+    <p>
+      Hypervisors may allow for virtual machines to be placed into
+      resource partitions, potentially with nesting of said partitions.
+      The <code>resource</code> element groups together configuration
+      related to resource partitioning. It currently supports a child
+      element <code>partition</code> whose content defines the path
+      of the resource partition in which to place the domain. If no
+      partition is listed, then the domain will be placed in a default
+      partition. It is the responsibility of the app/admin to ensure
+      that the partition exists prior to starting the guest. Only the
+      (hypervisor specific) default partition can be assumed to exist
+      by default.
+    </p>
+<pre>
+  ...
+  &lt;resource&gt;
+    &lt;partition&gt;/virtualmachines/production&lt;/partition&gt;
+  &lt;/resource&gt;
+  ...
+</pre>
+
+    <p>
+      Resource partitions are currently supported by the QEMU and
+      LXC drivers, which map partition paths onto cgroups directories,
+      in all mounted controllers. <span class="since">Since 1.0.5</span>
+    </p>
+
     <h3><a name="elementsCPU">CPU model and topology</a></h3>
 
     <p>

docs/schemas/domaincommon.rng

@@ -537,6 +537,10 @@
       <optional>
         <ref name="numatune"/>
       </optional>
+
+      <optional>
+        <ref name="respartition"/>
+      </optional>
     </interleave>
   </define>
 
@@ -680,6 +684,14 @@
     </element>
   </define>
 
+  <define name="respartition">
+    <element name="resource">
+      <element name="partition">
+        <ref name="absFilePath"/>
+      </element>
+    </element>
+  </define>
+
   <define name="clock">
     <optional>
       <element name="clock">