migration: Initial support of fixed-ram feature for analyze-migration.py

In order to allow analyze-migration.py script to work with migration
streams that have the 'fixed-ram' capability set it's required to have
access to the stream's configuration object. This commit enables this
by making migration json writer part of MigrationState struct, allowing
the configuration object be serialized to json.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>

migration/migration.c

@@ -2260,6 +2260,7 @@ void migrate_init(MigrationState *s)
     error_free(s->error);
     s->error = NULL;
     s->hostname = NULL;
+    s->vmdesc = NULL;
 
     migrate_set_state(&s->state, MIGRATION_STATUS_NONE, MIGRATION_STATUS_SETUP);
 

migration/savevm.c

@@ -1206,13 +1206,25 @@ void qemu_savevm_non_migratable_list(strList **reasons)
 
 void qemu_savevm_state_header(QEMUFile *f)
 {
+    MigrationState *s = migrate_get_current();
+
+    s->vmdesc = json_writer_new(false);
+
     trace_savevm_state_header();
     qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
     qemu_put_be32(f, QEMU_VM_FILE_VERSION);
 
-    if (migrate_get_current()->send_configuration) {
+    if (s->send_configuration) {
         qemu_put_byte(f, QEMU_VM_CONFIGURATION);
-        vmstate_save_state(f, &vmstate_configuration, &savevm_state, 0);
+        /*
+         * This starts the main json object and is paired with the
+         * json_writer_end_object in
+         * qemu_savevm_state_complete_precopy_non_iterable
+         */
+        json_writer_start_object(s->vmdesc, NULL);
+        json_writer_start_object(s->vmdesc, "configuration");
+        vmstate_save_state(f, &vmstate_configuration, &savevm_state, s->vmdesc);
+        json_writer_end_object(s->vmdesc);
     }
 }
 
@@ -1237,8 +1249,6 @@ void qemu_savevm_state_setup(QEMUFile *f)
     Error *local_err = NULL;
     int ret;
 
-    ms->vmdesc = json_writer_new(false);
-    json_writer_start_object(ms->vmdesc, NULL);
     json_writer_int64(ms->vmdesc, "page_size", qemu_target_page_size());
     json_writer_start_array(ms->vmdesc, "devices");
 

scripts/analyze-migration.py

@@ -23,7 +23,7 @@ import argparse
 import collections
 import struct
 import sys
-
+import math
 
 def mkdir_p(path):
     try:
@@ -119,11 +119,16 @@ class RamSection(object):
         self.file = file
         self.section_key = section_key
         self.TARGET_PAGE_SIZE = ramargs['page_size']
+        self.TARGET_PAGE_BITS = math.log2(self.TARGET_PAGE_SIZE)
         self.dump_memory = ramargs['dump_memory']
         self.write_memory = ramargs['write_memory']
+        self.fixed_ram = ramargs['fixed-ram']
         self.sizeinfo = collections.OrderedDict()
+        self.bitmap_offset = collections.OrderedDict()
+        self.pages_offset = collections.OrderedDict()
         self.data = collections.OrderedDict()
         self.data['section sizes'] = self.sizeinfo
+        self.ram_read = False
         self.name = ''
         if self.write_memory:
             self.files = { }
@@ -140,7 +145,13 @@ class RamSection(object):
     def getDict(self):
         return self.data
 
+    def write_or_dump_fixed_ram(self):
+        pass
+
     def read(self):
+        if self.fixed_ram and self.ram_read:
+            return
+
         # Read all RAM sections
         while True:
             addr = self.file.read64()
@@ -167,7 +178,26 @@ class RamSection(object):
                         f.truncate(0)
                         f.truncate(len)
                         self.files[self.name] = f
+
+                    if self.fixed_ram:
+                        bitmap_len = self.file.read32()
+                        # skip the pages_offset which we don't need
+                        offset = self.file.tell() + 8
+                        self.bitmap_offset[self.name] = offset
+                        offset = ((offset + bitmap_len + self.TARGET_PAGE_SIZE - 1) //
+                                  self.TARGET_PAGE_SIZE) * self.TARGET_PAGE_SIZE
+                        self.pages_offset[self.name] = offset
+                        self.file.file.seek(offset + len)
+
                 flags &= ~self.RAM_SAVE_FLAG_MEM_SIZE
+                if self.fixed_ram:
+                    self.ram_read = True
+                # now we should rewind to the ram page offset of the first
+                # ram section
+                if self.fixed_ram:
+                    if self.write_memory or self.dump_memory:
+                        self.write_or_dump_fixed_ram()
+                        return
 
             if flags & self.RAM_SAVE_FLAG_COMPRESS:
                 if flags & self.RAM_SAVE_FLAG_CONTINUE:
@@ -208,7 +238,7 @@ class RamSection(object):
 
             # End of RAM section
             if flags & self.RAM_SAVE_FLAG_EOS:
-                break
+                return
 
             if flags != 0:
                 raise Exception("Unknown RAM flags: %x" % flags)
@@ -521,6 +551,7 @@ class MigrationDump(object):
         ramargs['page_size'] = self.vmsd_desc['page_size']
         ramargs['dump_memory'] = dump_memory
         ramargs['write_memory'] = write_memory
+        ramargs['fixed-ram'] = False
         self.section_classes[('ram',0)][1] = ramargs
 
         while True:
@@ -528,8 +559,20 @@ class MigrationDump(object):
             if section_type == self.QEMU_VM_EOF:
                 break
             elif section_type == self.QEMU_VM_CONFIGURATION:
-                section = ConfigurationSection(file)
+                config_desc = self.vmsd_desc.get('configuration')
-                section.read()
+                if config_desc is not None:
+                    config = VMSDSection(file, 1, config_desc, 'configuration')
+                    config.read()
+                    caps = config.data.get("configuration/capabilities")
+                    if caps is not None:
+                        caps = caps.data["capabilities"]
+                        if type(caps) != list:
+                            caps = [caps]
+                        for i in caps:
+                            # chomp out string length
+                            cap = i.data[1:].decode("utf8")
+                            if cap == "fixed-ram":
+                                ramargs['fixed-ram'] = True
             elif section_type == self.QEMU_VM_SECTION_START or section_type == self.QEMU_VM_SECTION_FULL:
                 section_id = file.read32()
                 name = file.readstr()