migration: Return -1 on memory allocation failure in ram.c

The function colo_init_ram_cache() currently returns -errno if
qemu_anon_ram_alloc() fails. However, the subsequent cleanup loop that
calls qemu_anon_ram_free() could potentially alter the value of errno.
This would cause the function to return a value that does not accurately
represent the original allocation failure.

This commit changes the return value to -1 on memory allocation failure.
This ensures that the return value is consistent and is not affected by
any errno changes that may occur during the free process.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Arun Menon <armenon@redhat.com>
Tested-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Link: https://lore.kernel.org/r/20250918-propagate_tpm_error-v14-20-36f11a6fb9d3@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

diff --git a/migration/ram.c b/migration/ram.c
index 6a0dcc04f436524a37672c41c38f201f06773374..163265a57f26fb1dc88d9797629d58c278e9afb7 100644 (file)
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3575,6 +3575,8 @@ static void colo_init_ram_state(void)
  * colo cache: this is for secondary VM, we cache the whole
  * memory of the secondary VM, it is need to hold the global lock
  * to call this helper.
+ *
+ * Returns zero to indicate success or -1 on error.
  */
 int colo_init_ram_cache(void)
 {
@@ -3594,7 +3596,7 @@ int colo_init_ram_cache(void)
                         block->colo_cache = NULL;
                     }
                 }
-                return -errno;
+                return -1;
             }
             if (!machine_dump_guest_core(current_machine)) {
                 qemu_madvise(block->colo_cache, block->used_length,