pve-qemu/debian/patches/pve/0060-savevm-async-improve-runstate-preservation-cleanup-e.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Fiona Ebner <f.ebner@proxmox.com>
Date: Mon, 31 Mar 2025 16:55:04 +0200
Subject: [PATCH] savevm-async: improve runstate preservation, cleanup error
 handling

Determine if VM needs to be started after finishing right before
actually stopping the VM instead of at the beginning.

In qmp_savevm_start(), the only path stopping the VM returns right
aftwards, so there is no need for the vm_start() handling after
errors.

Lastly, improve the code style for checking whether migrate_init()
failed by explicitly comparing against 0.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
[WB: squashed error handling commits, rename goto branch instead of
     inlining it]
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
---
 migration/savevm-async.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/migration/savevm-async.c b/migration/savevm-async.c
index 1e34c31e8b..d8d2c80475 100644
--- a/migration/savevm-async.c
+++ b/migration/savevm-async.c
@@ -178,6 +178,7 @@ static void process_savevm_finalize(void *opaque)
      */
     blk_set_aio_context(snap_state.target, qemu_get_aio_context(), NULL);
 
+    snap_state.vm_needs_start = runstate_is_running();
     ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
     if (ret < 0) {
         save_snapshot_error("vm_stop_force_state error %d", ret);
@@ -352,7 +353,6 @@ void qmp_savevm_start(const char *statefile, Error **errp)
     }
 
     /* initialize snapshot info */
-    snap_state.vm_needs_start = runstate_is_running();
     snap_state.bs_pos = 0;
     snap_state.total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
     snap_state.blocker = NULL;
@@ -364,13 +364,14 @@ void qmp_savevm_start(const char *statefile, Error **errp)
     }
 
     if (!statefile) {
+        snap_state.vm_needs_start = runstate_is_running();
         vm_stop(RUN_STATE_SAVE_VM);
         snap_state.state = SAVE_STATE_COMPLETED;
         return;
     }
 
     if (qemu_savevm_state_blocked(errp)) {
-        return;
+        goto fail;
     }
 
     /* Open the image */
@@ -380,12 +381,12 @@ void qmp_savevm_start(const char *statefile, Error **errp)
     snap_state.target = blk_new_open(statefile, NULL, options, bdrv_oflags, &local_err);
     if (!snap_state.target) {
         error_setg(errp, "failed to open '%s'", statefile);
-        goto restart;
+        goto fail;
     }
     target_bs = blk_bs(snap_state.target);
     if (!target_bs) {
         error_setg(errp, "failed to open '%s' - no block driver state", statefile);
-        goto restart;
+        goto fail;
     }
 
     QIOChannel *ioc = QIO_CHANNEL(qio_channel_savevm_async_new(snap_state.target,
@@ -394,7 +395,7 @@ void qmp_savevm_start(const char *statefile, Error **errp)
 
     if (!snap_state.file) {
         error_setg(errp, "failed to open '%s'", statefile);
-        goto restart;
+        goto fail;
     }
 
     /*
@@ -402,8 +403,8 @@ void qmp_savevm_start(const char *statefile, Error **errp)
      * State is cleared in process_savevm_co, but has to be initialized
      * here (blocking main thread, from QMP) to avoid race conditions.
      */
-    if (migrate_init(ms, errp)) {
-        return;
+    if (migrate_init(ms, errp) != 0) {
+        goto fail;
     }
     memset(&mig_stats, 0, sizeof(mig_stats));
     ms->to_dst_file = snap_state.file;
@@ -418,7 +419,7 @@ void qmp_savevm_start(const char *statefile, Error **errp)
     if (ret != 0) {
         error_setg_errno(errp, -ret, "savevm state setup failed: %s",
                          local_err ? error_get_pretty(local_err) : "unknown error");
-        return;
+        goto fail;
     }
 
     /* Async processing from here on out happens in iohandler context, so let
@@ -436,14 +437,8 @@ void qmp_savevm_start(const char *statefile, Error **errp)
 
     return;
 
-restart:
-
+fail:
     save_snapshot_error("setup failed");
-
-    if (snap_state.vm_needs_start) {
-        vm_start();
-        snap_state.vm_needs_start = false;
-    }
 }
 
 static void coroutine_fn wait_for_close_co(void *opaque)