vmstate: be able to store/save a pci device from a pointer

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/hw.h

@@ -629,6 +629,14 @@ extern const VMStateDescription vmstate_pci_device;
     .offset     = vmstate_offset_value(_state, _field, PCIDevice),   \
 }
 
+#define VMSTATE_PCI_DEVICE_POINTER(_field, _state) {                 \
+    .name       = (stringify(_field)),                               \
+    .size       = sizeof(PCIDevice),                                 \
+    .vmsd       = &vmstate_pci_device,                               \
+    .flags      = VMS_STRUCT|VMS_POINTER,                            \
+    .offset     = vmstate_offset_pointer(_state, _field, PCIDevice), \
+}
+
 extern const VMStateDescription vmstate_pcie_device;
 
 #define VMSTATE_PCIE_DEVICE(_field, _state) {                        \