[RFC PATCH 4/4] migration: Check migration error after loadvm

[Fabiano Rosas <farosas@suse.de>]

We're currently only checking the QEMUFile error after
qemu_loadvm_state(). Check the migration error as well to avoid
missing errors that might be set by the multifd recv thread.

This doesn't break compat between 9.2 and 10.0 because 9.2 still has
the multifd recv threads stuck at sync when the source channel shuts
down. I.e. it doesn't have commit 1d457daf86 ("migration/multifd:
Further remove the SYNC on complete"). QEMU versions with that commit
will have compat broken with versions containing this commit. This is
not an issue because both will be present in 10.0, but development
trees might see a migration error.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/savevm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index bc375db282..4046faf009 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2940,7 +2940,11 @@ int qemu_loadvm_state(QEMUFile *f)
 
     /* When reaching here, it must be precopy */
     if (ret == 0) {
-        ret = qemu_file_get_error(f);
+        if (migrate_has_error(migrate_get_current())) {
+            ret = -EINVAL;
+        } else {
+            ret = qemu_file_get_error(f);
+        }
     }
 
     /*
-- 
2.35.3