qemu: min_guarantee: Parameter 'min_guarantee' not supported

The 'min_guarantee' is used by VMware ESX and OpenVZ drivers,
with qemu however, libvirt should report error when starting a domain,
because this element is not used.
Resolves https://bugzilla.redhat.com/show_bug.cgi?id=1122455

docs/formatdomain.html.in

@@ -726,7 +726,8 @@
       <dt><code>min_guarantee</code></dt>
       <dd> The optional <code>min_guarantee</code> element is the guaranteed
         minimum memory allocation for the guest. The units for this value are
-        kibibytes (i.e. blocks of 1024 bytes)</dd>
+        kibibytes (i.e. blocks of 1024 bytes). This element is only supported
+        by VMware ESX and OpenVZ drivers.</dd>
     </dl>
 
 

src/qemu/qemu_process.c

@@ -4020,6 +4020,13 @@ int qemuProcessStart(virConnectPtr conn,
                                     flags & VIR_QEMU_PROCESS_START_COLD) < 0)
         goto cleanup;
 
+    if (vm->def->mem.min_guarantee) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("Parameter 'min_guarantee' "
+                         "not supported by QEMU."));
+        goto cleanup;
+    }
+
     if (VIR_ALLOC(priv->monConfig) < 0)
         goto cleanup;