migration: new cmd MIG_CMD_POSTCOPY_RESUME

[mirror_qemu.git] / migration / savevm.c

diff --git a/migration/savevm.c b/migration/savevm.c
index 7176b350d5a5937cc8cecd69c78fe638792ae267..a7e793eef7b02a536624d05887ccdb9002f7e588 100644 (file)
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -80,6 +80,7 @@ enum qemu_vm_cmd {
     MIG_CMD_POSTCOPY_RAM_DISCARD,  /* A list of pages to discard that
                                       were previously sent during
                                       precopy but are dirty. */
+    MIG_CMD_POSTCOPY_RESUME,       /* resume postcopy on dest */
     MIG_CMD_PACKAGED,          /* Send a wrapped stream within this stream */
     MIG_CMD_RECV_BITMAP,       /* Request for recved bitmap on dst */
     MIG_CMD_MAX
@@ -98,6 +99,7 @@ static struct mig_cmd_args {
     [MIG_CMD_POSTCOPY_RUN]     = { .len =  0, .name = "POSTCOPY_RUN" },
     [MIG_CMD_POSTCOPY_RAM_DISCARD] = {
                                    .len = -1, .name = "POSTCOPY_RAM_DISCARD" },
+    [MIG_CMD_POSTCOPY_RESUME]  = { .len =  0, .name = "POSTCOPY_RESUME" },
     [MIG_CMD_PACKAGED]         = { .len =  4, .name = "PACKAGED" },
     [MIG_CMD_RECV_BITMAP]      = { .len = -1, .name = "RECV_BITMAP" },
     [MIG_CMD_MAX]              = { .len = -1, .name = "MAX" },
@@ -958,6 +960,12 @@ void qemu_savevm_send_postcopy_run(QEMUFile *f)
     qemu_savevm_command_send(f, MIG_CMD_POSTCOPY_RUN, 0, NULL);
 }
 
+void qemu_savevm_send_postcopy_resume(QEMUFile *f)
+{
+    trace_savevm_send_postcopy_resume();
+    qemu_savevm_command_send(f, MIG_CMD_POSTCOPY_RESUME, 0, NULL);
+}
+
 void qemu_savevm_send_recv_bitmap(QEMUFile *f, char *block_name)
 {
     size_t len;
@@ -1768,6 +1776,30 @@ static int loadvm_postcopy_handle_run(MigrationIncomingState *mis)
     return LOADVM_QUIT;
 }
 
+static int loadvm_postcopy_handle_resume(MigrationIncomingState *mis)
+{
+    if (mis->state != MIGRATION_STATUS_POSTCOPY_RECOVER) {
+        error_report("%s: illegal resume received", __func__);
+        /* Don't fail the load, only for this. */
+        return 0;
+    }
+
+    /*
+     * This means source VM is ready to resume the postcopy migration.
+     * It's time to switch state and release the fault thread to
+     * continue service page faults.
+     */
+    migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_RECOVER,
+                      MIGRATION_STATUS_POSTCOPY_ACTIVE);
+    qemu_sem_post(&mis->postcopy_pause_sem_fault);
+
+    trace_loadvm_postcopy_handle_resume();
+
+    /* TODO: Tell source that "we are ready" */
+
+    return 0;
+}
+
 /**
  * Immediately following this command is a blob of data containing an embedded
  * chunk of migration stream; read it and load it.
@@ -1933,6 +1965,9 @@ static int loadvm_process_command(QEMUFile *f)
     case MIG_CMD_POSTCOPY_RAM_DISCARD:
         return loadvm_postcopy_ram_handle_discard(mis, len);
 
+    case MIG_CMD_POSTCOPY_RESUME:
+        return loadvm_postcopy_handle_resume(mis);
+
     case MIG_CMD_RECV_BITMAP:
         return loadvm_handle_recv_bitmap(mis, len);
     }