From b6ab7a067fe5a28fbc309c78876bd81bcee80376 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A1n=20Tomko?= <jtomko@redhat.com>
Date: Fri, 19 Oct 2012 16:58:05 +0200
Subject: [PATCH] migrate: v2: use VIR_DOMAIN_XML_MIGRATABLE when available

In v2 migration protocol, XML is obtained by calling domainGetXMLDesc.
This includes the default USB controller in XML, which breaks migration
to older libvirt (before 0.9.2).

Commit 409b5f549530e7b3a33f4505f2cad2e26896107c
    qemu: Emit compatible XML when migrating a domain
only fixed this for v3 migration.

This patch uses the new VIR_DOMAIN_XML_MIGRATABLE flag (detected by
VIR_DRV_FEATURE_XML_MIGRATABLE) to obtain XML without the default controller,
enabling backward v2 migration.
---
 src/libvirt.c          | 13 ++++++++++---
 src/libvirt_internal.h |  5 +++++
 src/qemu/qemu_driver.c |  1 +
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/libvirt.c b/src/libvirt.c
index 6d659652e6..33cf7cbeb6 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -4620,6 +4620,7 @@ virDomainMigrateVersion2 (virDomainPtr domain,
     int cookielen = 0, ret;
     virDomainInfo info;
     virErrorPtr orig_err = NULL;
+    unsigned int getxml_flags = 0;
     int cancelled;
     VIR_DOMAIN_DEBUG(domain,
                      "dconn=%p, flags=%lx, dname=%s, uri=%s, bandwidth=%lu",
@@ -4646,9 +4647,15 @@ virDomainMigrateVersion2 (virDomainPtr domain,
         virDispatchError(domain->conn);
         return NULL;
     }
-    dom_xml = domain->conn->driver->domainGetXMLDesc(domain,
-                                                     VIR_DOMAIN_XML_SECURE |
-                                                     VIR_DOMAIN_XML_UPDATE_CPU);
+
+    if (VIR_DRV_SUPPORTS_FEATURE(domain->conn->driver, domain->conn,
+                                 VIR_DRV_FEATURE_XML_MIGRATABLE)) {
+        getxml_flags |= VIR_DOMAIN_XML_MIGRATABLE;
+    } else {
+        getxml_flags |= VIR_DOMAIN_XML_SECURE | VIR_DOMAIN_XML_UPDATE_CPU;
+    }
+
+    dom_xml = domain->conn->driver->domainGetXMLDesc(domain, getxml_flags);
     if (!dom_xml)
         return NULL;
 
diff --git a/src/libvirt_internal.h b/src/libvirt_internal.h
index 23e71535d0..71483e4695 100644
--- a/src/libvirt_internal.h
+++ b/src/libvirt_internal.h
@@ -95,6 +95,11 @@ enum {
      * messages).
      */
     VIR_DRV_FEATURE_PROGRAM_KEEPALIVE = 10,
+
+    /*
+     * Support for VIR_DOMAIN_XML_MIGRATABLE flag in domainGetXMLDesc
+     */
+    VIR_DRV_FEATURE_XML_MIGRATABLE = 11,
 };
 
 
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index feda4d9a21..2f83626127 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -1130,6 +1130,7 @@ qemudSupportsFeature (virConnectPtr conn ATTRIBUTE_UNUSED, int feature)
     case VIR_DRV_FEATURE_MIGRATE_CHANGE_PROTECTION:
     case VIR_DRV_FEATURE_FD_PASSING:
     case VIR_DRV_FEATURE_TYPED_PARAM_STRING:
+    case VIR_DRV_FEATURE_XML_MIGRATABLE:
         return 1;
     default:
         return 0;