qemu: Introduce label-size for NVDIMMs

For NVDIMM devices it is optionally possible to specify the size
of internal storage for namespaces. Namespaces are a feature that
allows users to partition the NVDIMM for different uses.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

docs/formatdomain.html.in

@@ -7123,6 +7123,9 @@ qemu-kvm -net nic,model=? /dev/null
     <target>
       <size unit='KiB'>524288</size>
       <node>1</node>
+      <label>
+        <size unit='KiB'>128</size>
+      </label>
     </target>
   </memory>
 </devices>
@@ -7204,6 +7207,20 @@ qemu-kvm -net nic,model=? /dev/null
           attach the memory to. The element shall be used only if the guest has
           NUMA nodes configured.
         </p>
+        <p>
+          For NVDIMM type devices one can optionally use
+          <code>label</code> and its subelement <code>size</code>
+          to configure the size of namespaces label storage
+          within the NVDIMM module. The <code>size</code> element
+          has usual meaning described
+          <a href="#elementsMemoryAllocation">here</a>.
+          For QEMU domains the following restrictions apply:
+        </p>
+        <ol>
+          <li>the minimum label size is 128KiB,</li>
+          <li>the remaining size (total-size - label-size) has to be aligned to
+            4KiB</li>
+        </ol>
       </dd>
     </dl>
 

docs/schemas/domaincommon.rng

@@ -4810,6 +4810,13 @@
             <ref name="unsignedInt"/>
           </element>
         </optional>
+        <optional>
+          <element name="label">
+            <element name="size">
+              <ref name="scaledInteger"/>
+            </element>
+          </element>
+        </optional>
       </interleave>
     </element>
   </define>