vmstate: add qom interface to get id

Add an interface to get the instance id, instead of depending on
Device and qdev_get_dev_path().

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

MAINTAINERS

@@ -2196,6 +2196,8 @@ Migration
 M: Juan Quintela <quintela@redhat.com>
 M: Dr. David Alan Gilbert <dgilbert@redhat.com>
 S: Maintained
+F: hw/core/vmstate-if.c
+F: include/hw/vmstate-if.h
 F: include/migration/
 F: migration/
 F: scripts/vmstate-static-checker.py

hw/core/Makefile.objs

@@ -9,6 +9,7 @@ common-obj-y += hotplug.o
 common-obj-$(CONFIG_SOFTMMU) += nmi.o
 common-obj-$(CONFIG_SOFTMMU) += vm-change-state-handler.o
 common-obj-y += cpu.o
+common-obj-y += vmstate-if.o
 
 common-obj-$(CONFIG_EMPTY_SLOT) += empty_slot.o
 common-obj-$(CONFIG_XILINX_AXI) += stream.o

hw/core/qdev.c

@@ -1087,9 +1087,18 @@ static void device_unparent(Object *obj)
     }
 }
 
+static char *
+device_vmstate_if_get_id(VMStateIf *obj)
+{
+    DeviceState *dev = DEVICE(obj);
+
+    return qdev_get_dev_path(dev);
+}
+
 static void device_class_init(ObjectClass *class, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(class);
+    VMStateIfClass *vc = VMSTATE_IF_CLASS(class);
 
     class->unparent = device_unparent;
 
@@ -1101,6 +1110,7 @@ static void device_class_init(ObjectClass *class, void *data)
      */
     dc->hotpluggable = true;
     dc->user_creatable = true;
+    vc->get_id = device_vmstate_if_get_id;
 }
 
 void device_class_set_parent_reset(DeviceClass *dc,
@@ -1158,6 +1168,10 @@ static const TypeInfo device_type_info = {
     .class_init = device_class_init,
     .abstract = true,
     .class_size = sizeof(DeviceClass),
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_VMSTATE_IF },
+        { }
+    }
 };
 
 static void qdev_register_types(void)

hw/core/vmstate-if.c

@@ -0,0 +1,23 @@
+/*
+ * VMState interface
+ *
+ * Copyright (c) 2009-2019 Red Hat Inc
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/vmstate-if.h"
+
+static const TypeInfo vmstate_if_info = {
+    .name = TYPE_VMSTATE_IF,
+    .parent = TYPE_INTERFACE,
+    .class_size = sizeof(VMStateIfClass),
+};
+
+static void vmstate_register_types(void)
+{
+    type_register_static(&vmstate_if_info);
+}
+
+type_init(vmstate_register_types);

include/hw/vmstate-if.h

@@ -0,0 +1,40 @@
+/*
+ * VMState interface
+ *
+ * Copyright (c) 2009-2019 Red Hat Inc
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef VMSTATE_IF_H
+#define VMSTATE_IF_H
+
+#include "qom/object.h"
+
+#define TYPE_VMSTATE_IF "vmstate-if"
+
+#define VMSTATE_IF_CLASS(klass)                                     \
+    OBJECT_CLASS_CHECK(VMStateIfClass, (klass), TYPE_VMSTATE_IF)
+#define VMSTATE_IF_GET_CLASS(obj)                           \
+    OBJECT_GET_CLASS(VMStateIfClass, (obj), TYPE_VMSTATE_IF)
+#define VMSTATE_IF(obj)                             \
+    INTERFACE_CHECK(VMStateIf, (obj), TYPE_VMSTATE_IF)
+
+typedef struct VMStateIf VMStateIf;
+
+typedef struct VMStateIfClass {
+    InterfaceClass parent_class;
+
+    char * (*get_id)(VMStateIf *obj);
+} VMStateIfClass;
+
+static inline char *vmstate_if_get_id(VMStateIf *vmif)
+{
+    if (!vmif) {
+        return NULL;
+    }
+
+    return VMSTATE_IF_GET_CLASS(vmif)->get_id(vmif);
+}
+
+#endif /* VMSTATE_IF_H */

include/migration/register.h

@@ -14,6 +14,8 @@
 #ifndef MIGRATION_REGISTER_H
 #define MIGRATION_REGISTER_H
 
+#include "hw/vmstate-if.h"
+
 typedef struct SaveVMHandlers {
     /* This runs inside the iothread lock.  */
     SaveStateHandler *save_state;

include/migration/vmstate.h

@@ -27,6 +27,8 @@
 #ifndef QEMU_VMSTATE_H
 #define QEMU_VMSTATE_H
 
+#include "hw/vmstate-if.h"
+
 typedef struct VMStateInfo VMStateInfo;
 typedef struct VMStateField VMStateField;
 

tests/Makefile.include

@@ -579,6 +579,7 @@ tests/test-qdev-global-props$(EXESUF): tests/test-qdev-global-props.o \
 	hw/core/irq.o \
 	hw/core/fw-path-provider.o \
 	hw/core/reset.o \
+	hw/core/vmstate-if.o \
 	$(test-qapi-obj-y)
 tests/test-vmstate$(EXESUF): tests/test-vmstate.o \
 	migration/vmstate.o migration/vmstate-types.o migration/qemu-file.o \