From 9708192479d7f6507392a338f8f43b3be4c8188d Mon Sep 17 00:00:00 2001
From: qihao <qihao_yewu@cmss.chinamobile.com>
Date: Mon, 18 Dec 2023 15:19:48 +0800
Subject: [PATCH] migration: Set downtime_start even for postcopy

cheery-pick from 62f5da7dd10a594fb30cebb5569dc738456f7131

Postcopy calculates its downtime separately.  It always sets
MigrationState.downtime properly, but not MigrationState.downtime_start.

Make postcopy do the same as other modes on properly recording the
timestamp when the VM is going to be stopped.  Drop the temporary variable
in postcopy_start() along the way.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231030163346.765724-2-peterx@redhat.com>
Signed-off-by: qihao_yewu <qihao_yewu@cmss.chinamobile.com>
---
 migration/migration.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 6b5445853a..7ca5b58839 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2989,7 +2989,6 @@ static int postcopy_start(MigrationState *ms)
     int ret;
     QIOChannelBuffer *bioc;
     QEMUFile *fb;
-    int64_t time_at_stop = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
     int64_t bandwidth = migrate_max_postcopy_bandwidth();
     bool restart_block = false;
     int cur_state = MIGRATION_STATUS_ACTIVE;
@@ -3002,6 +3001,8 @@ static int postcopy_start(MigrationState *ms)
     qemu_mutex_lock_iothread();
     trace_postcopy_start_set_run();
 
+    ms->downtime_start = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+
     qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
     global_state_store();
     ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
@@ -3112,7 +3113,7 @@ static int postcopy_start(MigrationState *ms)
     ms->postcopy_after_devices = true;
     notifier_list_notify(&migration_state_notifiers, ms);
 
-    ms->downtime =  qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - time_at_stop;
+    ms->downtime = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - ms->downtime_start;
 
     qemu_mutex_unlock_iothread();
 
-- 
2.27.0