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migration: dump vmstate info as a json file for static analysis 

This commit adds a new command, '-dump-vmstate', that takes a filename
as an argument.  When executed, QEMU will dump the vmstate information
for the machine type it's invoked with to the file, and quit.

The JSON-format output can then be used to compare the vmstate info for
different QEMU versions, specifically to test whether live migration
would break due to changes in the vmstate data.

A Python script that compares the output of such JSON dumps is included
in the following commit.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Amit Shah 2014-06-20 18:56:08 +05:30 committed by Juan Quintela
parent e325b49a32
commit abfd9ce341
4 changed files with 168 additions and 0 deletions
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2
include/migration/vmstate.h
View File

@ -788,4 +788,6 @@ int64_t self_announce_delay(int round)
return 50 + (SELF_ANNOUNCE_ROUNDS - round - 1) * 100;
}
void dump_vmstate_json_to_file(FILE *out_fp);
#endif

14
qemu-options.hx
View File

@ -3252,6 +3252,20 @@ STEXI
prepend a timestamp to each log message.(default:on)
ETEXI
DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
"-dump-vmstate <file>\n"
" Output vmstate information in JSON format to file.\n"
" Use the scripts/vmstate-static-checker.py file to\n"
" check for possible regressions in migration code\n"
" by comparing two such vmstate dumps.",
QEMU_ARCH_ALL)
STEXI
@item -dump-vmstate @var{file}
@findex -dump-vmstate
Dump json-encoded vmstate information for current machine type to file
in @var{file}
ETEXI
HXCOMM This is the last statement. Insert new options before this line!
STEXI
@end table

139
savevm.c
View File

@ -24,6 +24,7 @@
#include "config-host.h"
#include "qemu-common.h"
#include "hw/boards.h"
#include "hw/hw.h"
#include "hw/qdev.h"
#include "net/net.h"
@ -240,6 +241,144 @@ static QTAILQ_HEAD(savevm_handlers, SaveStateEntry) savevm_handlers =
QTAILQ_HEAD_INITIALIZER(savevm_handlers);
static int global_section_id;
static void dump_vmstate_vmsd(FILE *out_file,
const VMStateDescription *vmsd, int indent,
bool is_subsection);
static void dump_vmstate_vmsf(FILE *out_file, const VMStateField *field,
int indent)
{
fprintf(out_file, "%*s{\n", indent, "");
indent += 2;
fprintf(out_file, "%*s\"field\": \"%s\",\n", indent, "", field->name);
fprintf(out_file, "%*s\"version_id\": %d,\n", indent, "",
field->version_id);
fprintf(out_file, "%*s\"field_exists\": %s,\n", indent, "",
field->field_exists ? "true" : "false");
fprintf(out_file, "%*s\"size\": %zu", indent, "", field->size);
if (field->vmsd != NULL) {
fprintf(out_file, ",\n");
dump_vmstate_vmsd(out_file, field->vmsd, indent, false);
}
fprintf(out_file, "\n%*s}", indent - 2, "");
}
static void dump_vmstate_vmss(FILE *out_file,
const VMStateSubsection *subsection,
int indent)
{
if (subsection->vmsd != NULL) {
dump_vmstate_vmsd(out_file, subsection->vmsd, indent, true);
}
}
static void dump_vmstate_vmsd(FILE *out_file,
const VMStateDescription *vmsd, int indent,
bool is_subsection)
{
if (is_subsection) {
fprintf(out_file, "%*s{\n", indent, "");
} else {
fprintf(out_file, "%*s\"%s\": {\n", indent, "", "Description");
}
indent += 2;
fprintf(out_file, "%*s\"name\": \"%s\",\n", indent, "", vmsd->name);
fprintf(out_file, "%*s\"version_id\": %d,\n", indent, "",
vmsd->version_id);
fprintf(out_file, "%*s\"minimum_version_id\": %d", indent, "",
vmsd->minimum_version_id);
if (vmsd->fields != NULL) {
const VMStateField *field = vmsd->fields;
bool first;
fprintf(out_file, ",\n%*s\"Fields\": [\n", indent, "");
first = true;
while (field->name != NULL) {
if (field->flags & VMS_MUST_EXIST) {
/* Ignore VMSTATE_VALIDATE bits; these don't get migrated */
field++;
continue;
}
if (!first) {
fprintf(out_file, ",\n");
}
dump_vmstate_vmsf(out_file, field, indent + 2);
field++;
first = false;
}
fprintf(out_file, "\n%*s]", indent, "");
}
if (vmsd->subsections != NULL) {
const VMStateSubsection *subsection = vmsd->subsections;
bool first;
fprintf(out_file, ",\n%*s\"Subsections\": [\n", indent, "");
first = true;
while (subsection->vmsd != NULL) {
if (!first) {
fprintf(out_file, ",\n");
}
dump_vmstate_vmss(out_file, subsection, indent + 2);
subsection++;
first = false;
}
fprintf(out_file, "\n%*s]", indent, "");
}
fprintf(out_file, "\n%*s}", indent - 2, "");
}
static void dump_machine_type(FILE *out_file)
{
MachineClass *mc;
mc = MACHINE_GET_CLASS(current_machine);
fprintf(out_file, " \"vmschkmachine\": {\n");
fprintf(out_file, " \"Name\": \"%s\"\n", mc->name);
fprintf(out_file, " },\n");
}
void dump_vmstate_json_to_file(FILE *out_file)
{
GSList *list, *elt;
bool first;
fprintf(out_file, "{\n");
dump_machine_type(out_file);
first = true;
list = object_class_get_list(TYPE_DEVICE, true);
for (elt = list; elt; elt = elt->next) {
DeviceClass *dc = OBJECT_CLASS_CHECK(DeviceClass, elt->data,
TYPE_DEVICE);
const char *name;
int indent = 2;
if (!dc->vmsd) {
continue;
}
if (!first) {
fprintf(out_file, ",\n");
}
name = object_class_get_name(OBJECT_CLASS(dc));
fprintf(out_file, "%*s\"%s\": {\n", indent, "", name);
indent += 2;
fprintf(out_file, "%*s\"Name\": \"%s\",\n", indent, "", name);
fprintf(out_file, "%*s\"version_id\": %d,\n", indent, "",
dc->vmsd->version_id);
fprintf(out_file, "%*s\"minimum_version_id\": %d,\n", indent, "",
dc->vmsd->minimum_version_id);
dump_vmstate_vmsd(out_file, dc->vmsd, indent, false);
fprintf(out_file, "\n%*s}", indent - 2, "");
first = false;
}
fprintf(out_file, "\n}\n");
fclose(out_file);
}
static int calculate_new_instance_id(const char *idstr)
{
SaveStateEntry *se;

13
vl.c
View File

@ -2935,6 +2935,7 @@ int main(int argc, char **argv, char **envp)
1024 * 1024;
ram_addr_t maxram_size = default_ram_size;
uint64_t ram_slots = 0;
FILE *vmstate_dump_file = NULL;
atexit(qemu_run_exit_notifiers);
error_set_progname(argv[0]);
@ -3944,6 +3945,13 @@ int main(int argc, char **argv, char **envp)
}
configure_msg(opts);
break;
case QEMU_OPTION_dump_vmstate:
vmstate_dump_file = fopen(optarg, "w");
if (vmstate_dump_file == NULL) {
fprintf(stderr, "open %s: %s\n", optarg, strerror(errno));
exit(1);
}
break;
default:
os_parse_cmd_args(popt->index, optarg);
}
@ -4495,6 +4503,11 @@ int main(int argc, char **argv, char **envp)
}
qdev_prop_check_global();
if (vmstate_dump_file) {
/* dump and exit */
dump_vmstate_json_to_file(vmstate_dump_file);
return 0;
}
if (incoming) {
Error *local_err = NULL;