[libvirt] [PATCH] qemu: Always enable the virtio balloon driver

[Adam Litke]

The behavior for the qemu balloon device has changed.  Formerly, a virtio
balloon device was provided by default.  Now, '-balloon virtio' must be
specified on the command line to enable it.  This patch causes libvirt to add
'-balloon virtio' to the command line whenever the -balloon option is
available.

Signed-off-by: Adam Litke <agl at us.ibm.com>

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 36bf9a2..07b0bd1 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -1113,6 +1113,8 @@ static unsigned int qemudComputeCmdFlags(const char *help,
         flags |= QEMUD_CMD_FLAG_MEM_PATH;
     if (strstr(help, "-chardev"))
         flags |= QEMUD_CMD_FLAG_CHARDEV;
+    if (strstr(help, "-balloon"))
+        flags |= QEMUD_CMD_FLAG_BALLOON;
 
     if (version >= 9000)
         flags |= QEMUD_CMD_FLAG_VNC_COLON;
@@ -2883,6 +2885,14 @@ int qemudBuildCommandLine(virConnectPtr conn,
         ADD_ARG_LIT(migrateFrom);
     }
 
+    /* QEMU changed its default behavior to not include the virtio balloon
+     * device.  Explicitly request it to ensure it will be present.
+     */
+    if (qemuCmdFlags & QEMUD_CMD_FLAG_BALLOON) {
+        ADD_ARG_LIT("-balloon");
+        ADD_ARG_LIT("virtio");
+    }
+
     ADD_ARG(NULL);
     ADD_ENV(NULL);
 
diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index e958850..28f59bf 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -78,6 +78,7 @@ enum qemud_cmd_flags {
     QEMUD_CMD_FLAG_ENABLE_KVM    = (1 << 23), /* Is the -enable-kvm flag available to "enable KVM full virtualization support" */
     QEMUD_CMD_FLAG_0_12          = (1 << 24),
     QEMUD_CMD_FLAG_MONITOR_JSON  = QEMUD_CMD_FLAG_0_12, /* JSON mode for monitor */
+    QEMUD_CMD_FLAG_BALLOON       = (1 << 25), /* -balloon available */
 };
 
 /* Main driver state */


-- 
Thanks,
Adam