vmstate: Add support for VBUFFERS

Support for buffer that are pointed by a pointer (i.e. not embedded)
where the size that we want to use is a field in the state.
We also need a new place to store where to start in the middle of the
buffer, as now it is a pointer, not the offset of the 1st field.

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

2 files changed, 34 insertions, 6 deletions

diff --git a/hw/hw.h b/hw/hw.h
index c3c0c9fe3e..47fb12b143 100644
--- a/hw/hw.h
+++ b/hw/hw.h
@@ -294,14 +294,17 @@ enum VMStateFlags {
     VMS_BUFFER           = 0x020,  /* static sized buffer */
     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 */
 };
 
 typedef struct {
     const char *name;
     size_t offset;
     size_t size;
+    size_t start;
     int num;
     size_t num_offset;
+    size_t size_offset;
     const VMStateInfo *info;
     enum VMStateFlags flags;
     const VMStateDescription *vmsd;
@@ -490,6 +493,17 @@ extern const VMStateInfo vmstate_info_unused_buffer;
     .offset       = vmstate_offset_buffer(_state, _field) + _start,  \
 }
 
+#define VMSTATE_VBUFFER(_field, _state, _version, _test, _start, _field_size) { \
+    .name         = (stringify(_field)),                             \
+    .version_id   = (_version),                                      \
+    .field_exists = (_test),                                         \
+    .size_offset  = vmstate_offset_value(_state, _field_size, int32_t),\
+    .info         = &vmstate_info_buffer,                            \
+    .flags        = VMS_VBUFFER|VMS_POINTER,                         \
+    .offset       = offsetof(_state, _field),                        \
+    .start        = (_start),                                        \
+}
+
 #define VMSTATE_BUFFER_UNSAFE_INFO(_field, _state, _version, _info, _size) { \
     .name       = (stringify(_field)),                               \
     .version_id = (_version),                                        \
@@ -683,6 +697,12 @@ extern const VMStateDescription vmstate_i2c_slave;
 #define VMSTATE_BUFFER_START_MIDDLE(_f, _s, _start) \
     VMSTATE_STATIC_BUFFER(_f, _s, 0, NULL, _start, sizeof(typeof_field(_s, _f)))
 
+#define VMSTATE_PARTIAL_VBUFFER(_f, _s, _size)                        \
+    VMSTATE_VBUFFER(_f, _s, 0, NULL, 0, _size)
+
+#define VMSTATE_SUB_VBUFFER(_f, _s, _start, _size)                    \
+    VMSTATE_VBUFFER(_f, _s, 0, NULL, _start, _size)
+
 #define VMSTATE_BUFFER_TEST(_f, _s, _test)                            \
     VMSTATE_STATIC_BUFFER(_f, _s, 0, _test, 0, sizeof(typeof_field(_s, _f)))
 
diff --git a/savevm.c b/savevm.c
index cafb9e7f0d..1125ef2d53 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1143,7 +1143,11 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
              field->version_id <= version_id)) {
             void *base_addr = opaque + field->offset;
             int ret, i, n_elems = 1;
+            int size = field->size;
 
+            if (field->flags & VMS_VBUFFER) {
+                size = *(int32_t *)(opaque+field->size_offset);
+            }
             if (field->flags & VMS_ARRAY) {
                 n_elems = field->num;
             } else if (field->flags & VMS_VARRAY_INT32) {
@@ -1152,10 +1156,10 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                 n_elems = *(uint16_t *)(opaque+field->num_offset);
             }
             if (field->flags & VMS_POINTER) {
-                base_addr = *(void **)base_addr;
+                base_addr = *(void **)base_addr + field->start;
             }
             for (i = 0; i < n_elems; i++) {
-                void *addr = base_addr + field->size * i;
+                void *addr = base_addr + size * i;
 
                 if (field->flags & VMS_ARRAY_OF_POINTER) {
                     addr = *(void **)addr;
@@ -1163,7 +1167,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                 if (field->flags & VMS_STRUCT) {
                     ret = vmstate_load_state(f, field->vmsd, addr, field->vmsd->version_id);
                 } else {
-                    ret = field->info->get(f, addr, field->size);
+                    ret = field->info->get(f, addr, size);
 
                 }
                 if (ret < 0) {
@@ -1192,7 +1196,11 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
             field->field_exists(opaque, vmsd->version_id)) {
             void *base_addr = opaque + field->offset;
             int i, n_elems = 1;
+            int size = field->size;
 
+            if (field->flags & VMS_VBUFFER) {
+                size = *(int32_t *)(opaque+field->size_offset);
+            }
             if (field->flags & VMS_ARRAY) {
                 n_elems = field->num;
             } else if (field->flags & VMS_VARRAY_INT32) {
@@ -1201,10 +1209,10 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                 n_elems = *(uint16_t *)(opaque+field->num_offset);
             }
             if (field->flags & VMS_POINTER) {
-                base_addr = *(void **)base_addr;
+                base_addr = *(void **)base_addr + field->start;
             }
             for (i = 0; i < n_elems; i++) {
-                void *addr = base_addr + field->size * i;
+                void *addr = base_addr + size * i;
 
                 if (field->flags & VMS_ARRAY_OF_POINTER) {
                     addr = *(void **)addr;
@@ -1212,7 +1220,7 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                 if (field->flags & VMS_STRUCT) {
                     vmstate_save_state(f, field->vmsd, addr);
                 } else {
-                    field->info->put(f, addr, field->size);
+                    field->info->put(f, addr, size);
                 }
             }
         }