vmstate: Add support for multiplying size for a constant

When the size that we want to transmit is in another field, but in an
unit different that bytes
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/hw.h

@@ -295,6 +295,7 @@ enum VMStateFlags {
     VMS_ARRAY_OF_POINTER = 0x040,
     VMS_VARRAY_UINT16    = 0x080,  /* Array with size in uint16_t field */
     VMS_VBUFFER          = 0x100,  /* Buffer with size in int32_t field */
+    VMS_MULTIPLY         = 0x200,  /* multiply "size" field by field_size */
 };
 
 typedef struct {
@@ -485,6 +486,18 @@ extern const VMStateInfo vmstate_info_unused_buffer;
     .offset       = vmstate_offset_buffer(_state, _field) + _start,  \
 }
 
+#define VMSTATE_BUFFER_MULTIPLY(_field, _state, _version, _test, _start, _field_size, _multiply) { \
+    .name         = (stringify(_field)),                             \
+    .version_id   = (_version),                                      \
+    .field_exists = (_test),                                         \
+    .size_offset  = vmstate_offset_value(_state, _field_size, uint32_t),\
+    .size         = (_multiply),                                      \
+    .info         = &vmstate_info_buffer,                            \
+    .flags        = VMS_VBUFFER|VMS_MULTIPLY,                        \
+    .offset       = offsetof(_state, _field),                        \
+    .start        = (_start),                                        \
+}
+
 #define VMSTATE_VBUFFER(_field, _state, _version, _test, _start, _field_size) { \
     .name         = (stringify(_field)),                             \
     .version_id   = (_version),                                      \

savevm.c

@@ -1147,6 +1147,9 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
 
             if (field->flags & VMS_VBUFFER) {
                 size = *(int32_t *)(opaque+field->size_offset);
+                if (field->flags & VMS_MULTIPLY) {
+                    size *= field->size;
+                }
             }
             if (field->flags & VMS_ARRAY) {
                 n_elems = field->num;
@@ -1200,6 +1203,9 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
 
             if (field->flags & VMS_VBUFFER) {
                 size = *(int32_t *)(opaque+field->size_offset);
+                if (field->flags & VMS_MULTIPLY) {
+                    size *= field->size;
+                }
             }
             if (field->flags & VMS_ARRAY) {
                 n_elems = field->num;