[Qemu-devel] [PATCH V2 1/3] vmstate: introduce get_bufsize entry in VMStateField

[Mitsyanko Igor]

New get_bufsize field in VMStateField is supposed to help us easily add 
save/restore
support of dynamically allocated buffers in device's states.
There are some cases when information about size of dynamically allocated 
buffer is
already presented in specific device's state structure, but in such a form that
can not be used with existing VMStateField interface. Currently, we either can 
get size from
another variable in device's state as it is with VMSTATE_VBUFFER_* macros, or 
we can
also multiply value kept in a variable by a constant with 
VMSTATE_BUFFER_MULTIPLY
macro. If we need to perform any other action, we're forced to add additional
variable with size information to device state structure with the only intention
to use it in VMStateDescription. This approach is not very pretty. Adding extra
flags to VMStateFlags enum for every other possible operation with size field
seems redundant, and still it would't cover cases when we need to perform a set 
of
operations to get size value.
With get_bufsize callback we can calculate size of dynamic array in whichever
way we need. We don't need .size_offset field anymore, so we can remove it from
VMState Field structure to compensate for extra memory consuption because of
get_bufsize addition. Macros VMSTATE_VBUFFER* are modified to use new callback
instead of .size_offset. Macro VMSTATE_BUFFER_MULTIPLY and VMFlag VMS_MULTIPLY
are removed completely as they are now redundant.

Signed-off-by: Mitsyanko Igor <address@hidden>
---
 hw/g364fb.c    |    7 ++++++-
 hw/hw.h        |   41 +++++++----------------------------------
 hw/m48t59.c    |    7 ++++++-
 hw/mac_nvram.c |    8 +++++++-
 hw/onenand.c   |    7 ++++++-
 savevm.c       |   10 ++--------
 6 files changed, 34 insertions(+), 46 deletions(-)

diff --git a/hw/g364fb.c b/hw/g364fb.c
index 34fb08c..1ab36c2 100644
--- a/hw/g364fb.c
+++ b/hw/g364fb.c
@@ -495,6 +495,11 @@ static int g364fb_post_load(void *opaque, int version_id)
     return 0;
 }
 
+static int g364fb_get_vramsize(void *opaque, int version_id)
+{
+    return ((G364State *)opaque)->vram_size;
+}
+
 static const VMStateDescription vmstate_g364fb = {
     .name = "g364fb",
     .version_id = 1,
@@ -502,7 +507,7 @@ static const VMStateDescription vmstate_g364fb = {
     .minimum_version_id_old = 1,
     .post_load = g364fb_post_load,
     .fields = (VMStateField[]) {
-        VMSTATE_VBUFFER_UINT32(vram, G364State, 1, NULL, 0, vram_size),
+        VMSTATE_VBUFFER(vram, G364State, 1, NULL, 0, g364fb_get_vramsize),
         VMSTATE_BUFFER_UNSAFE(color_palette, G364State, 0, 256 * 3),
         VMSTATE_BUFFER_UNSAFE(cursor_palette, G364State, 0, 9),
         VMSTATE_UINT16_ARRAY(cursor, G364State, 512),
diff --git a/hw/hw.h b/hw/hw.h
index efa04d1..a2a43b6 100644
--- a/hw/hw.h
+++ b/hw/hw.h
@@ -303,7 +303,6 @@ 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 */
     VMS_VARRAY_UINT8     = 0x400,  /* Array with size in uint8_t field*/
     VMS_VARRAY_UINT32    = 0x800,  /* Array with size in uint32_t field*/
 };
@@ -315,12 +314,12 @@ typedef struct {
     size_t start;
     int num;
     size_t num_offset;
-    size_t size_offset;
     const VMStateInfo *info;
     enum VMStateFlags flags;
     const VMStateDescription *vmsd;
     int version_id;
     bool (*field_exists)(void *opaque, int version_id);
+    int (*get_bufsize)(void *opaque, int version_id);
 } VMStateField;
 
 typedef struct VMStateSubsection {
@@ -584,34 +583,11 @@ 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) { \
+#define VMSTATE_VBUFFER(_field, _state, _version, _test, _start, _get_bufsize) 
{ \
     .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),                                      \
-    .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_VBUFFER_UINT32(_field, _state, _version, _test, _start, 
_field_size) { \
-    .name         = (stringify(_field)),                             \
-    .version_id   = (_version),                                      \
-    .field_exists = (_test),                                         \
-    .size_offset  = vmstate_offset_value(_state, _field_size, uint32_t),\
+    .get_bufsize  = (_get_bufsize),                                  \
     .info         = &vmstate_info_buffer,                            \
     .flags        = VMS_VBUFFER|VMS_POINTER,                         \
     .offset       = offsetof(_state, _field),                        \
@@ -891,14 +867,11 @@ extern const VMStateDescription vmstate_hid_ptr_device;
 #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_PARTIAL_VBUFFER_UINT32(_f, _s, _size)                        \
-    VMSTATE_VBUFFER_UINT32(_f, _s, 0, NULL, 0, _size)
+#define VMSTATE_PARTIAL_VBUFFER(_f, _s, _get_bufsize)                 \
+    VMSTATE_VBUFFER(_f, _s, 0, NULL, 0, _get_bufsize)
 
-#define VMSTATE_SUB_VBUFFER(_f, _s, _start, _size)                    \
-    VMSTATE_VBUFFER(_f, _s, 0, NULL, _start, _size)
+#define VMSTATE_SUB_VBUFFER(_f, _s, _start, _get_bufsize)             \
+    VMSTATE_VBUFFER(_f, _s, 0, NULL, _start, _get_bufsize)
 
 #define VMSTATE_BUFFER_TEST(_f, _s, _test)                            \
     VMSTATE_STATIC_BUFFER(_f, _s, 0, _test, 0, sizeof(typeof_field(_s, _f)))
diff --git a/hw/m48t59.c b/hw/m48t59.c
index c043996..4e4c9f3 100644
--- a/hw/m48t59.c
+++ b/hw/m48t59.c
@@ -582,6 +582,11 @@ static const MemoryRegionOps nvram_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
+static int m48t59_get_bufsize(void *opaque, int version_id)
+{
+    return ((M48t59State *)opaque)->size;
+}
+
 static const VMStateDescription vmstate_m48t59 = {
     .name = "m48t59",
     .version_id = 1,
@@ -590,7 +595,7 @@ static const VMStateDescription vmstate_m48t59 = {
     .fields      = (VMStateField[]) {
         VMSTATE_UINT8(lock, M48t59State),
         VMSTATE_UINT16(addr, M48t59State),
-        VMSTATE_VBUFFER_UINT32(buffer, M48t59State, 0, NULL, 0, size),
+        VMSTATE_VBUFFER(buffer, M48t59State, 0, NULL, 0, m48t59_get_bufsize),
         VMSTATE_END_OF_LIST()
     }
 };
diff --git a/hw/mac_nvram.c b/hw/mac_nvram.c
index ed0a2b7..f4367f8 100644
--- a/hw/mac_nvram.c
+++ b/hw/mac_nvram.c
@@ -100,13 +100,19 @@ static const MemoryRegionOps macio_nvram_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
+static int macio_nvram_get_datasize(void *opaque, int version_id)
+{
+    return ((MacIONVRAMState *)opaque)->size;
+}
+
 static const VMStateDescription vmstate_macio_nvram = {
     .name = "macio_nvram",
     .version_id = 1,
     .minimum_version_id = 1,
     .minimum_version_id_old = 1,
     .fields      = (VMStateField[]) {
-        VMSTATE_VBUFFER_UINT32(data, MacIONVRAMState, 0, NULL, 0, size),
+        VMSTATE_VBUFFER(data, MacIONVRAMState, 0, NULL, 0,
+                macio_nvram_get_datasize),
         VMSTATE_END_OF_LIST()
     }
 };
diff --git a/hw/onenand.c b/hw/onenand.c
index a9d8d67..3e2016b 100644
--- a/hw/onenand.c
+++ b/hw/onenand.c
@@ -160,6 +160,11 @@ static int onenand_post_load(void *opaque, int version_id)
     return 0;
 }
 
+static int onenand_get_blockwpsize(void *opaque, int version_id)
+{
+    return ((OneNANDState *)opaque)->blocks;
+}
+
 static const VMStateDescription vmstate_onenand = {
     .name = "onenand",
     .version_id = 1,
@@ -181,7 +186,7 @@ static const VMStateDescription vmstate_onenand = {
         VMSTATE_UINT16(intstatus, OneNANDState),
         VMSTATE_UINT16(wpstatus, OneNANDState),
         VMSTATE_INT32(secs_cur, OneNANDState),
-        VMSTATE_PARTIAL_VBUFFER(blockwp, OneNANDState, blocks),
+        VMSTATE_PARTIAL_VBUFFER(blockwp, OneNANDState, 
onenand_get_blockwpsize),
         VMSTATE_UINT8(ecc.cp, OneNANDState),
         VMSTATE_UINT16_ARRAY(ecc.lp, OneNANDState, 2),
         VMSTATE_UINT16(ecc.count, OneNANDState),
diff --git a/savevm.c b/savevm.c
index f153c25..831c50a 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1412,10 +1412,7 @@ int vmstate_load_state(QEMUFile *f, const 
VMStateDescription *vmsd,
             int size = field->size;
 
             if (field->flags & VMS_VBUFFER) {
-                size = *(int32_t *)(opaque+field->size_offset);
-                if (field->flags & VMS_MULTIPLY) {
-                    size *= field->size;
-                }
+                size = field->get_bufsize(opaque, version_id);
             }
             if (field->flags & VMS_ARRAY) {
                 n_elems = field->num;
@@ -1476,10 +1473,7 @@ void vmstate_save_state(QEMUFile *f, const 
VMStateDescription *vmsd,
             int size = field->size;
 
             if (field->flags & VMS_VBUFFER) {
-                size = *(int32_t *)(opaque+field->size_offset);
-                if (field->flags & VMS_MULTIPLY) {
-                    size *= field->size;
-                }
+                size = field->get_bufsize(opaque, vmsd->version_id);
             }
             if (field->flags & VMS_ARRAY) {
                 n_elems = field->num;
-- 
1.7.4.1