migration: Allow to suppress vmdesc submission

We now always send a JSON blob describing the migration file format as part
of the migration stream. However, some tools built around QEMU have proven
to stumble over this.

This patch gives the user the chance to disable said self-describing part of
the migration stream. To disable vmdesc submission, just add

  -machine suppress-vmdesc=on

to your QEMU command line.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/hw/core/machine.c b/hw/core/machine.c
index e3a3e2ab73701ff045bb3e24fef0b8ce8ca8d6c1..cb1185ada479892fc027ca6d868d589bd62e126d 100644 (file)
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -254,6 +254,20 @@ static void machine_set_iommu(Object *obj, bool value, Error **errp)
     ms->iommu = value;
 }
 
+static void machine_set_suppress_vmdesc(Object *obj, bool value, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    ms->suppress_vmdesc = value;
+}
+
+static bool machine_get_suppress_vmdesc(Object *obj, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    return ms->suppress_vmdesc;
+}
+
 static int error_on_sysbus_device(SysBusDevice *sbdev, void *opaque)
 {
     error_report("Option '-device %s' cannot be handled by this machine",
@@ -377,6 +391,12 @@ static void machine_initfn(Object *obj)
     object_property_set_description(obj, "iommu",
                                     "Set on/off to enable/disable Intel IOMMU (VT-d)",
                                     NULL);
+    object_property_add_bool(obj, "suppress-vmdesc",
+                             machine_get_suppress_vmdesc,
+                             machine_set_suppress_vmdesc, NULL);
+    object_property_set_description(obj, "suppress-vmdesc",
+                                    "Set on to disable self-describing migration",
+                                    NULL);
 
     /* Register notifier when init is done for sysbus sanity checks */
     ms->sysbus_notifier.notify = machine_init_notify;

diff --git a/include/hw/boards.h b/include/hw/boards.h
index f44d6f542aae303443199e79a671fc10c76e9451..1feea2b176467ff7f320c4fc59d1b256dbb4c039 100644 (file)
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -143,6 +143,7 @@ struct MachineState {
     bool usb;
     char *firmware;
     bool iommu;
+    bool suppress_vmdesc;
 
     ram_addr_t ram_size;
     ram_addr_t maxram_size;

diff --git a/qemu-options.hx b/qemu-options.hx
index ad07ddecd037aa5acba48eabab77e9bd5bc686fb..c513352ea8095a41a20a35e33daf6b97d828e039 100644 (file)
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -39,7 +39,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
     "                mem-merge=on|off controls memory merge support (default: on)\n"
     "                iommu=on|off controls emulated Intel IOMMU (VT-d) support (default=off)\n"
     "                aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n"
-    "                dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n",
+    "                dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n"
+    "                suppress-vmdesc=on|off disables self-describing migration (default=off)\n",
     QEMU_ARCH_ALL)
 STEXI
 @item -machine [type=]@var{name}[,prop=@var{value}[,...]]

diff --git a/savevm.c b/savevm.c
index 54510e9b8a1fe2a460ab900809362ee87226d73b..e7d97eea935eb47c7374fcbbcbcdf869a6e124f6 100644 (file)
--- a/savevm.c
+++ b/savevm.c
@@ -710,6 +710,12 @@ int qemu_savevm_state_iterate(QEMUFile *f)
     return ret;
 }
 
+static bool should_send_vmdesc(void)
+{
+    MachineState *machine = MACHINE(qdev_get_machine());
+    return !machine->suppress_vmdesc;
+}
+
 void qemu_savevm_state_complete(QEMUFile *f)
 {
     QJSON *vmdesc;
@@ -782,9 +788,11 @@ void qemu_savevm_state_complete(QEMUFile *f)
     qjson_finish(vmdesc);
     vmdesc_len = strlen(qjson_get_str(vmdesc));
 
-    qemu_put_byte(f, QEMU_VM_VMDESCRIPTION);
-    qemu_put_be32(f, vmdesc_len);
-    qemu_put_buffer(f, (uint8_t *)qjson_get_str(vmdesc), vmdesc_len);
+    if (should_send_vmdesc()) {
+        qemu_put_byte(f, QEMU_VM_VMDESCRIPTION);
+        qemu_put_be32(f, vmdesc_len);
+        qemu_put_buffer(f, (uint8_t *)qjson_get_str(vmdesc), vmdesc_len);
+    }
     object_unref(OBJECT(vmdesc));
 
     qemu_fflush(f);