libxl: Normalize MAC address in device conf when hotplugging a netdev

Similar to commits 55ce6564 and 6c17606b in the qemu driver, make
separate copies of persistent and live device config and normalize the MAC
address between the two. This avoids having different MAC address for the
persistent and live config, ensuring the device has the same address when
the persistent config takes affect after a VM restart.
Signed-off-by: NJim Fehlig <jfehlig@suse.com>
Reviewed-by: NLaine Stump <laine@redhat.com>

src/libxl/libxl_driver.c

@@ -4096,6 +4096,31 @@ libxlDomainUpdateDeviceConfig(virDomainDefPtr vmdef, virDomainDeviceDefPtr dev)
 }
 
 
+static void
+libxlDomainAttachDeviceNormalize(const virDomainDeviceDef *devConf,
+                                 virDomainDeviceDefPtr devLive)
+{
+    /*
+     * Fixup anything that needs to be identical in the live and
+     * config versions of DeviceDef, but might not be. Do this by
+     * changing the contents of devLive. This is done after all
+     * post-parse tweaks and validation, so be very careful about what
+     * changes are made.
+     */
+
+    /* MAC address should be identical in both DeviceDefs, but if it
+     * wasn't specified in the XML, and was instead autogenerated, it
+     * will be different for the two since they are each the result of
+     * a separate parser call. If it *was* specified, it will already
+     * be the same, so copying does no harm.
+     */
+
+    if (devConf->type == VIR_DOMAIN_DEVICE_NET)
+        virMacAddrSet(&devLive->data.net->mac, &devConf->data.net->mac);
+
+}
+
+
 static int
 libxlDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
                              unsigned int flags)
@@ -4104,7 +4129,9 @@ libxlDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
     libxlDriverConfigPtr cfg = libxlDriverConfigGet(driver);
     virDomainObjPtr vm = NULL;
     virDomainDefPtr vmdef = NULL;
-    virDomainDeviceDefPtr dev = NULL;
+    virDomainDeviceDefPtr devConf = NULL;
+    virDomainDeviceDef devConfSave = { 0 };
+    virDomainDeviceDefPtr devLive = NULL;
     int ret = -1;
 
     virCheckFlags(VIR_DOMAIN_DEVICE_MODIFY_LIVE |
@@ -4123,28 +4150,36 @@ libxlDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
         goto endjob;
 
     if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG) {
-        if (!(dev = virDomainDeviceDefParse(xml, vm->def,
-                                            driver->xmlopt, NULL,
-                                            VIR_DOMAIN_DEF_PARSE_INACTIVE)))
+        if (!(devConf = virDomainDeviceDefParse(xml, vm->def,
+                                                driver->xmlopt, NULL,
+                                                VIR_DOMAIN_DEF_PARSE_INACTIVE)))
             goto endjob;
 
         /* Make a copy for updated domain. */
         if (!(vmdef = virDomainObjCopyPersistentDef(vm, driver->xmlopt, NULL)))
             goto endjob;
 
-        if (libxlDomainAttachDeviceConfig(vmdef, dev) < 0)
+        /*
+         * devConf will be NULLed out by
+         * libxlDomainAttachDeviceConfig(), so save it for later use by
+         * libxlDomainAttachDeviceNormalize()
+         */
+        devConfSave = *devConf;
+
+        if (libxlDomainAttachDeviceConfig(vmdef, devConf) < 0)
             goto endjob;
     }
 
     if (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE) {
-        /* If dev exists it was created to modify the domain config. Free it. */
-        virDomainDeviceDefFree(dev);
-        if (!(dev = virDomainDeviceDefParse(xml, vm->def,
+        if (!(devLive = virDomainDeviceDefParse(xml, vm->def,
                                             driver->xmlopt, NULL,
                                             VIR_DOMAIN_DEF_PARSE_INACTIVE)))
             goto endjob;
 
-        if (libxlDomainAttachDeviceLive(driver, vm, dev) < 0)
+        if (flags & VIR_DOMAIN_AFFECT_CONFIG)
+            libxlDomainAttachDeviceNormalize(&devConfSave, devLive);
+
+        if (libxlDomainAttachDeviceLive(driver, vm, devLive) < 0)
             goto endjob;
 
         /*
@@ -4171,7 +4206,8 @@ libxlDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
 
  cleanup:
     virDomainDefFree(vmdef);
-    virDomainDeviceDefFree(dev);
+    virDomainDeviceDefFree(devConf);
+    virDomainDeviceDefFree(devLive);
     virDomainObjEndAPI(&vm);
     virObjectUnref(cfg);
     return ret;