[RFC,v1,20/26] kvm: vmi: intercept live migration

diff --git a/accel/kvm/vmi.c b/accel/kvm/vmi.c
index 90906478b4..ea7191e48d 100644
--- a/accel/kvm/vmi.c
+++ b/accel/kvm/vmi.c
@@ -21,6 +21,8 @@ 
 #include "chardev/char.h"
 #include "chardev/char-fe.h"
 #include "migration/vmstate.h"
+#include "migration/migration.h"
+#include "migration/misc.h"
 
 #include "sysemu/vmi-intercept.h"
 #include "sysemu/vmi-handshake.h"
@@ -58,6 +60,7 @@  typedef struct VMIntrospection {
     int64_t vm_start_time;
 
     Notifier machine_ready;
+    Notifier migration_state_change;
     bool created_from_command_line;
 
     bool kvmi_hooked;
@@ -74,9 +77,11 @@  static const char *action_string[] = {
     "suspend",
     "resume",
     "force-reset",
+    "migrate",
 };
 
 static bool suspend_pending;
+static bool migrate_pending;
 
 #define TYPE_VM_INTROSPECTION "introspection"
 
@@ -88,6 +93,15 @@  static bool suspend_pending;
 static Error *vm_introspection_init(VMIntrospection *i);
 static void vm_introspection_reset(void *opaque);
 
+static void migration_state_notifier(Notifier *notifier, void *data)
+{
+    MigrationState *s = data;
+
+    if (migration_has_failed(s)) {
+        migrate_pending = false;
+    }
+}
+
 static void machine_ready(Notifier *notifier, void *data)
 {
     VMIntrospection *i = container_of(notifier, VMIntrospection, machine_ready);
@@ -144,6 +158,9 @@  static void complete(UserCreatable *uc, Error **errp)
 
     ic->uniq = i;
 
+    i->migration_state_change.notify = migration_state_notifier;
+    add_migration_state_change_notifier(&i->migration_state_change);
+
     qemu_register_reset(vm_introspection_reset, i);
 }
 
@@ -478,6 +495,9 @@  static void continue_with_the_intercepted_action(VMIntrospection *i)
     case VMI_INTERCEPT_SUSPEND:
         vm_stop(RUN_STATE_PAUSED);
         break;
+    case VMI_INTERCEPT_MIGRATE:
+        start_live_migration_thread(migrate_get_current());
+        break;
     default:
         error_report("VMI: %s: unexpected action %d",
                      __func__, i->intercepted_action);
@@ -571,9 +591,9 @@  static void chr_event_open(VMIntrospection *i)
 {
     Error *local_err = NULL;
 
-    if (suspend_pending) {
-        info_report("VMI: %s: too soon (suspend=%d)",
-                    __func__, suspend_pending);
+    if (suspend_pending || migrate_pending) {
+        info_report("VMI: %s: too soon (suspend=%d, migrate=%d)",
+                    __func__, suspend_pending, migrate_pending);
         maybe_disable_socket_reconnect(i);
         qemu_chr_fe_disconnect(&i->sock);
         return;
@@ -608,7 +628,7 @@  static void chr_event_close(VMIntrospection *i)
     cancel_unhook_timer(i);
     cancel_handshake_timer(i);
 
-    if (suspend_pending) {
+    if (suspend_pending || migrate_pending) {
         maybe_disable_socket_reconnect(i);
 
         if (i->intercepted_action != VMI_INTERCEPT_NONE) {
@@ -680,6 +700,9 @@  static bool record_intercept_action(VMI_intercept_command action)
         break;
     case VMI_INTERCEPT_FORCE_RESET:
         break;
+    case VMI_INTERCEPT_MIGRATE:
+        migrate_pending = true;
+        break;
     default:
         return false;
     }
diff --git a/include/sysemu/vmi-intercept.h b/include/sysemu/vmi-intercept.h
index ef591b49e7..b4a9a3faa7 100644
--- a/include/sysemu/vmi-intercept.h
+++ b/include/sysemu/vmi-intercept.h
@@ -15,6 +15,7 @@  typedef enum {
     VMI_INTERCEPT_SUSPEND,
     VMI_INTERCEPT_RESUME,
     VMI_INTERCEPT_FORCE_RESET,
+    VMI_INTERCEPT_MIGRATE,
 } VMI_intercept_command;
 
 bool vm_introspection_intercept(VMI_intercept_command ic, Error **errp);
diff --git a/migration/migration.c b/migration/migration.c
index 187ac0410c..222037d739 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -55,6 +55,8 @@ 
 #include "qemu/queue.h"
 #include "multifd.h"
 
+#include "sysemu/vmi-intercept.h"
+
 #define MAX_THROTTLE  (32 << 20)      /* Migration transfer speed throttling */
 
 /* Amount of time to allocate to each "chunk" of bandwidth-throttled
@@ -3471,6 +3473,13 @@  static void *migration_thread(void *opaque)
     return NULL;
 }
 
+void start_live_migration_thread(MigrationState *s)
+{
+    qemu_thread_create(&s->thread, "live_migration", migration_thread, s,
+                    QEMU_THREAD_JOINABLE);
+    s->migration_thread_running = true;
+}
+
 void migrate_fd_connect(MigrationState *s, Error *error_in)
 {
     Error *local_err = NULL;
@@ -3534,9 +3543,12 @@  void migrate_fd_connect(MigrationState *s, Error *error_in)
         migrate_fd_cleanup(s);
         return;
     }
-    qemu_thread_create(&s->thread, "live_migration", migration_thread, s,
-                       QEMU_THREAD_JOINABLE);
-    s->migration_thread_running = true;
+
+    if (vm_introspection_intercept(VMI_INTERCEPT_MIGRATE, &error_in)) {
+        return;
+    }
+
+    start_live_migration_thread(s);
 }
 
 void migration_global_dump(Monitor *mon)
diff --git a/migration/migration.h b/migration/migration.h
index 507284e563..eb5668e1f2 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -263,6 +263,8 @@  struct MigrationState
     uint8_t clear_bitmap_shift;
 };
 
+void start_live_migration_thread(MigrationState *s);
+
 void migrate_set_state(int *state, int old_state, int new_state);
 
 void migration_fd_process_incoming(QEMUFile *f, Error **errp);