[PATCH QEMU HCI-8.1 v6 02/34] migration/cpr-exec: restore RAM write access if exec fails

[Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>]

With -cpr-ram-rdonly the RAM blocks are made read-only right before
execve().  If execve() fails, the VM resumes in the old QEMU with
read-only RAM and crashes on the first write.  Make it writable again.

Fixes: 91da25f20471 ("migration/cpr-exec: add '-cpr-ram-rdonly' option to mark RAM blocks as RO #VSTOR-101579")
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 migration/cpr-exec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/migration/cpr-exec.c b/migration/cpr-exec.c
index 9fd3515753a..c4bdf2cb99f 100644
--- a/migration/cpr-exec.c
+++ b/migration/cpr-exec.c
@@ -224,6 +224,9 @@ static void cpr_exec_cb(void *opaque)
     error_setg_errno(&err, errno, "execvp %s failed", argv[0]);
     g_clear_pointer(&argv, g_strfreev);
     cpr_exec_unpreserve_fds();
+    if (cpr_ram_rdonly) {
+        cpr_ram_restore_rw();
+    }
 
     error_report_err(error_copy(err));
     migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED);

-- 
2.47.1