[Qemu-devel] [PATCH RFC] Mark a device as non-migratable

[Cam Macdonell <cam@cs.ualberta.ca>]

How does this look for marking the device as non-migratable?  It adds a field
'no_migrate' to the SaveStateEntry and tests for it in vmstate_save.  This would
replace anything that touches memory.

Cam

---
 hw/hw.h  |    1 +
 savevm.c |   32 +++++++++++++++++++++++++++++---
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/hw/hw.h b/hw/hw.h
index d78d814..7c93f08 100644
--- a/hw/hw.h
+++ b/hw/hw.h
@@ -263,6 +263,7 @@ int register_savevm_live(const char *idstr,
                          void *opaque);
 
 void unregister_savevm(const char *idstr, void *opaque);
+void mark_no_migrate(const char *idstr, void *opaque);
 
 typedef void QEMUResetHandler(void *opaque);
 
diff --git a/savevm.c b/savevm.c
index 017695b..2642a9c 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1023,6 +1023,7 @@ typedef struct SaveStateEntry {
     LoadStateHandler *load_state;
     const VMStateDescription *vmsd;
     void *opaque;
+    int no_migrate;
 } SaveStateEntry;
 
 
@@ -1069,6 +1070,7 @@ int register_savevm_live(const char *idstr,
     se->load_state = load_state;
     se->opaque = opaque;
     se->vmsd = NULL;
+    se->no_migrate = 0;
 
     if (instance_id == -1) {
         se->instance_id = calculate_new_instance_id(idstr);
@@ -1103,6 +1105,19 @@ void unregister_savevm(const char *idstr, void *opaque)
     }
 }
 
+/* mark a device as not to be migrated, that is the device should be
+   unplugged before migration */
+void mark_no_migrate(const char *idstr, void *opaque)
+{
+    SaveStateEntry *se;
+
+    QTAILQ_FOREACH(se, &savevm_handlers, entry) {
+        if (strcmp(se->idstr, idstr) == 0 && se->opaque == opaque) {
+            se->no_migrate = 1;
+        }
+    }
+}
+
 int vmstate_register_with_alias_id(int instance_id,
                                    const VMStateDescription *vmsd,
                                    void *opaque, int alias_id,
@@ -1277,13 +1292,19 @@ static int vmstate_load(QEMUFile *f, SaveStateEntry *se, int version_id)
     return vmstate_load_state(f, se->vmsd, se->opaque, version_id);
 }
 
-static void vmstate_save(QEMUFile *f, SaveStateEntry *se)
+static int vmstate_save(QEMUFile *f, SaveStateEntry *se)
 {
+    if (se->no_migrate) {
+        return -1;
+    }
+
     if (!se->vmsd) {         /* Old style */
         se->save_state(f, se->opaque);
-        return;
+        return 0;
     }
     vmstate_save_state(f,se->vmsd, se->opaque);
+
+    return 0;
 }
 
 #define QEMU_VM_FILE_MAGIC           0x5145564d
@@ -1377,6 +1398,7 @@ int qemu_savevm_state_iterate(Monitor *mon, QEMUFile *f)
 int qemu_savevm_state_complete(Monitor *mon, QEMUFile *f)
 {
     SaveStateEntry *se;
+    int r;
 
     cpu_synchronize_all_states();
 
@@ -1409,7 +1431,11 @@ int qemu_savevm_state_complete(Monitor *mon, QEMUFile *f)
         qemu_put_be32(f, se->instance_id);
         qemu_put_be32(f, se->version_id);
 
-        vmstate_save(f, se);
+        r = vmstate_save(f, se);
+        if (r < 0) {
+            monitor_printf(mon, "cannot migrate with device '%s'\n", se->idstr);
+            return r;
+        }
     }
 
     qemu_put_byte(f, QEMU_VM_EOF);
-- 
1.6.3.2.198.g6096d