qemu: Reject migration with memory-hotplug if destination doesn't support it

If destination libvirt doesn't support memory hotplug since all the
support was introduced by adding new elements the destination would
attempt to start qemu with an invalid configuration. The worse part is
that qemu might hang in such situation.

Fix this by sending a required migration feature called 'memory-hotplug'
to the destination. If the destination doesn't recognize it it will fail
the migration.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1248350

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index f5866c41210fdcdd5b85244ea04f28c2a6d33d1d..824126f687f62372228a3660f443fdb54bf0fcf3 100644 (file)
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -86,6 +86,7 @@ enum qemuMigrationCookieFlags {
     QEMU_MIGRATION_COOKIE_FLAG_NETWORK,
     QEMU_MIGRATION_COOKIE_FLAG_NBD,
     QEMU_MIGRATION_COOKIE_FLAG_STATS,
+    QEMU_MIGRATION_COOKIE_FLAG_MEMORY_HOTPLUG,
 
     QEMU_MIGRATION_COOKIE_FLAG_LAST
 };
@@ -98,7 +99,8 @@ VIR_ENUM_IMPL(qemuMigrationCookieFlag,
               "persistent",
               "network",
               "nbd",
-              "statistics");
+              "statistics",
+              "memory-hotplug");
 
 enum qemuMigrationCookieFeatures {
     QEMU_MIGRATION_COOKIE_GRAPHICS  = (1 << QEMU_MIGRATION_COOKIE_FLAG_GRAPHICS),
@@ -107,6 +109,7 @@ enum qemuMigrationCookieFeatures {
     QEMU_MIGRATION_COOKIE_NETWORK = (1 << QEMU_MIGRATION_COOKIE_FLAG_NETWORK),
     QEMU_MIGRATION_COOKIE_NBD = (1 << QEMU_MIGRATION_COOKIE_FLAG_NBD),
     QEMU_MIGRATION_COOKIE_STATS = (1 << QEMU_MIGRATION_COOKIE_FLAG_STATS),
+    QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG = (1 << QEMU_MIGRATION_COOKIE_FLAG_MEMORY_HOTPLUG),
 };
 
 typedef struct _qemuMigrationCookieGraphics qemuMigrationCookieGraphics;
@@ -1352,6 +1355,9 @@ qemuMigrationBakeCookie(qemuMigrationCookiePtr mig,
         qemuMigrationCookieAddStatistics(mig, dom) < 0)
         return -1;
 
+    if (flags & QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG)
+        mig->flagsMandatory |= QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG;
+
     if (!(*cookieout = qemuMigrationCookieXMLFormatStr(driver, mig)))
         return -1;
 
@@ -2974,6 +2980,11 @@ qemuMigrationBeginPhase(virQEMUDriverPtr driver,
         }
     }
 
+    if (vm->def->mem.max_memory ||
+        (vm->newDef &&
+         vm->newDef->mem.max_memory))
+        cookieFlags |= QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG;
+
     if (!(mig = qemuMigrationEatCookie(driver, vm, NULL, 0, 0)))
         goto cleanup;