migration: Change SaveStateEntry.instance_id into uint32_t

It was always used as 32bit, so define it as used to be clear.
Instead of using -1 as the auto-gen magic value, we switch to
UINT32_MAX.  We also make sure that we don't auto-gen this value to
avoid overflowed instance IDs without being noticed.

Suggested-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

5 files changed, 14 insertions, 12 deletions

diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
index f2c3a7f309..54b8731fca 100644
--- a/hw/intc/apic_common.c
+++ b/hw/intc/apic_common.c
@@ -268,7 +268,7 @@ static void apic_common_realize(DeviceState *dev, Error **errp)
     APICCommonState *s = APIC_COMMON(dev);
     APICCommonClass *info;
     static DeviceState *vapic;
-    int instance_id = s->id;
+    uint32_t instance_id = s->id;
 
     info = APIC_COMMON_GET_CLASS(s);
     info->realize(dev, errp);
diff --git a/include/migration/register.h b/include/migration/register.h
index 00c38ebe9f..c1dcff0f90 100644
--- a/include/migration/register.h
+++ b/include/migration/register.h
@@ -71,7 +71,7 @@ typedef struct SaveVMHandlers {
 } SaveVMHandlers;
 
 int register_savevm_live(const char *idstr,
-                         int instance_id,
+                         uint32_t instance_id,
                          int version_id,
                          const SaveVMHandlers *ops,
                          void *opaque);
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index ed74dd5624..01790b8d9b 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -1160,7 +1160,7 @@ bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque);
 #define  VMSTATE_INSTANCE_ID_ANY  -1
 
 /* Returns: 0 on success, -1 on failure */
-int vmstate_register_with_alias_id(VMStateIf *obj, int instance_id,
+int vmstate_register_with_alias_id(VMStateIf *obj, uint32_t instance_id,
                                    const VMStateDescription *vmsd,
                                    void *base, int alias_id,
                                    int required_for_version,
diff --git a/migration/savevm.c b/migration/savevm.c
index 8dab99efc4..adfdca26ac 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -233,7 +233,7 @@ typedef struct CompatEntry {
 typedef struct SaveStateEntry {
     QTAILQ_ENTRY(SaveStateEntry) entry;
     char idstr[256];
-    int instance_id;
+    uint32_t instance_id;
     int alias_id;
     int version_id;
     /* version id read from the stream */
@@ -667,10 +667,10 @@ void dump_vmstate_json_to_file(FILE *out_file)
     fclose(out_file);
 }
 
-static int calculate_new_instance_id(const char *idstr)
+static uint32_t calculate_new_instance_id(const char *idstr)
 {
     SaveStateEntry *se;
-    int instance_id = 0;
+    uint32_t instance_id = 0;
 
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
         if (strcmp(idstr, se->idstr) == 0
@@ -678,6 +678,8 @@ static int calculate_new_instance_id(const char *idstr)
             instance_id = se->instance_id + 1;
         }
     }
+    /* Make sure we never loop over without being noticed */
+    assert(instance_id != VMSTATE_INSTANCE_ID_ANY);
     return instance_id;
 }
 
@@ -755,7 +757,7 @@ static void savevm_state_handler_remove(SaveStateEntry *se)
    Meanwhile pass -1 as instance_id if you do not already have a clearly
    distinguishing id for all instances of your device class. */
 int register_savevm_live(const char *idstr,
-                         int instance_id,
+                         uint32_t instance_id,
                          int version_id,
                          const SaveVMHandlers *ops,
                          void *opaque)
@@ -809,7 +811,7 @@ void unregister_savevm(VMStateIf *obj, const char *idstr, void *opaque)
     }
 }
 
-int vmstate_register_with_alias_id(VMStateIf *obj, int instance_id,
+int vmstate_register_with_alias_id(VMStateIf *obj, uint32_t instance_id,
                                    const VMStateDescription *vmsd,
                                    void *opaque, int alias_id,
                                    int required_for_version,
@@ -1625,7 +1627,7 @@ int qemu_save_device_state(QEMUFile *f)
     return qemu_file_get_error(f);
 }
 
-static SaveStateEntry *find_se(const char *idstr, int instance_id)
+static SaveStateEntry *find_se(const char *idstr, uint32_t instance_id)
 {
     SaveStateEntry *se;
 
@@ -2292,7 +2294,7 @@ qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
     /* Find savevm section */
     se = find_se(idstr, instance_id);
     if (se == NULL) {
-        error_report("Unknown savevm section or instance '%s' %d. "
+        error_report("Unknown savevm section or instance '%s' %"PRIu32". "
                      "Make sure that your current VM setup matches your "
                      "saved VM setup, including any hotplugged devices",
                      idstr, instance_id);
@@ -2316,7 +2318,7 @@ qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
 
     ret = vmstate_load(f, se);
     if (ret < 0) {
-        error_report("error while loading state for instance 0x%x of"
+        error_report("error while loading state for instance 0x%"PRIx32" of"
                      " device '%s'", instance_id, idstr);
         return ret;
     }
diff --git a/stubs/vmstate.c b/stubs/vmstate.c
index 6951d9fdc5..cc4fe41dfc 100644
--- a/stubs/vmstate.c
+++ b/stubs/vmstate.c
@@ -4,7 +4,7 @@
 const VMStateDescription vmstate_dummy = {};
 
 int vmstate_register_with_alias_id(VMStateIf *obj,
-                                   int instance_id,
+                                   uint32_t instance_id,
                                    const VMStateDescription *vmsd,
                                    void *base, int alias_id,
                                    int required_for_version,