vmstate: add subsections code
This commit adds subsections for each device section.
Subsections is the way to handle information that don't need to be sent
to de destination of a migration because its values are not needed. It is
the way to handle optional information. Notice that only the source can
decide if the information is optional or not. The destination needs to
understand all subsections that it receives to have a sucessful load.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/savevm.c b/savevm.c
index ee27989..7a1de3c 100644
--- a/savevm.c
+++ b/savevm.c
@@ -551,6 +551,19 @@
return size1 - size;
}
+static int qemu_peek_byte(QEMUFile *f)
+{
+ if (f->is_write)
+ abort();
+
+ if (f->buf_index >= f->buf_size) {
+ qemu_fill_buffer(f);
+ if (f->buf_index >= f->buf_size)
+ return 0;
+ }
+ return f->buf[f->buf_index];
+}
+
int qemu_get_byte(QEMUFile *f)
{
if (f->is_write)
@@ -1198,10 +1211,16 @@
}
}
+static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
+ void *opaque);
+static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
+ void *opaque);
+
int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque, int version_id)
{
VMStateField *field = vmsd->fields;
+ int ret;
if (version_id > vmsd->version_id) {
return -EINVAL;
@@ -1223,7 +1242,7 @@
(!field->field_exists &&
field->version_id <= version_id)) {
void *base_addr = opaque + field->offset;
- int ret, i, n_elems = 1;
+ int i, n_elems = 1;
int size = field->size;
if (field->flags & VMS_VBUFFER) {
@@ -1261,6 +1280,10 @@
}
field++;
}
+ ret = vmstate_subsection_load(f, vmsd, opaque);
+ if (ret != 0) {
+ return ret;
+ }
if (vmsd->post_load) {
return vmsd->post_load(opaque, version_id);
}
@@ -1313,6 +1336,7 @@
}
field++;
}
+ vmstate_subsection_save(f, vmsd, opaque);
}
static int vmstate_load(QEMUFile *f, SaveStateEntry *se, int version_id)
@@ -1341,6 +1365,7 @@
#define QEMU_VM_SECTION_PART 0x02
#define QEMU_VM_SECTION_END 0x03
#define QEMU_VM_SECTION_FULL 0x04
+#define QEMU_VM_SUBSECTION 0x05
int qemu_savevm_state_begin(Monitor *mon, QEMUFile *f, int blk_enable,
int shared)
@@ -1529,6 +1554,65 @@
return NULL;
}
+static const VMStateDescription *vmstate_get_subsection(const VMStateSubsection *sub, char *idstr)
+{
+ while(sub && sub->needed) {
+ if (strcmp(idstr, sub->vmsd->name) == 0) {
+ return sub->vmsd;
+ }
+ sub++;
+ }
+ return NULL;
+}
+
+static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
+ void *opaque)
+{
+ while (qemu_peek_byte(f) == QEMU_VM_SUBSECTION) {
+ char idstr[256];
+ int ret;
+ uint8_t version_id, subsection, len;
+ const VMStateDescription *sub_vmsd;
+
+ subsection = qemu_get_byte(f);
+ len = qemu_get_byte(f);
+ qemu_get_buffer(f, (uint8_t *)idstr, len);
+ idstr[len] = 0;
+ version_id = qemu_get_be32(f);
+
+ sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr);
+ if (sub_vmsd == NULL) {
+ return -ENOENT;
+ }
+ ret = vmstate_load_state(f, sub_vmsd, opaque, version_id);
+ if (ret) {
+ return ret;
+ }
+ }
+ return 0;
+}
+
+static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
+ void *opaque)
+{
+ const VMStateSubsection *sub = vmsd->subsections;
+
+ while (sub && sub->needed) {
+ if (sub->needed(opaque)) {
+ const VMStateDescription *vmsd = sub->vmsd;
+ uint8_t len;
+
+ qemu_put_byte(f, QEMU_VM_SUBSECTION);
+ len = strlen(vmsd->name);
+ qemu_put_byte(f, len);
+ qemu_put_buffer(f, (uint8_t *)vmsd->name, len);
+ qemu_put_be32(f, vmsd->version_id);
+ vmstate_save_state(f, vmsd, opaque);
+ }
+ sub++;
+ }
+}
+
typedef struct LoadStateEntry {
QLIST_ENTRY(LoadStateEntry) entry;
SaveStateEntry *se;
