conf: Introduce sgio for hostdev

"sgio" is only valid for scsi host device.

docs/formatdomain.html.in

@@ -2414,7 +2414,12 @@
         and <code>virNodeDeviceReAttach</code> (or <code>virsh
         nodedev-reattach</code>) after hot-unplug or stopping the
         guest. For SCSI device, user is responsible to make sure the device
-        is not used by host.</dd>
+        is not used by host.
+        The optional <code>sgio</code> (<span class="since">since 1.0.6</span>)
+        attribute indicates whether the kernel will filter unprivileged
+        SG_IO commands for the disk, valid settings are "filtered" or
+        "unfiltered". Defaults to "filtered".
+      </dd>
       <dt><code>source</code></dt>
       <dd>The source element describes the device as seen from the host.
       The USB device can either be addressed by vendor / product id using the

docs/schemas/domaincommon.rng

@@ -3234,6 +3234,14 @@
     <attribute name="type">
       <value>scsi</value>
     </attribute>
+    <optional>
+      <attribute name="sgio">
+        <choice>
+          <value>filtered</value>
+          <value>unfiltered</value>
+        </choice>
+      </attribute>
+    </optional>
     <element name="source">
       <interleave>
         <ref name="sourceinfoadapter"/>