[RFC PATCH v1 1/1] migration: Disable postcopy + multifd migration

[Leonardo Bras]

Since the introduction of multifd, it's possible to perform a multifd
migration and finish it using postcopy.

A bug introduced by yank (fixed on cfc3bcf373) was previously preventing
a successful use of this migration scenario, and now it should be
working on most cases.

But since there is not enough testing/support nor any reported users for
this scenario, we should disable this combination before it may cause any
problems for users.

Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Leonardo Bras <leobras@redhat.com>
---
 migration/migration.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/migration/migration.c b/migration/migration.c
index ae2025d9d8..c601964b0e 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1356,6 +1356,11 @@ static bool migrate_caps_check(bool *cap_list,
             error_setg(errp, "Postcopy is not compatible with ignore-shared");
             return false;
         }
+
+        if (cap_list[MIGRATION_CAPABILITY_MULTIFD]) {
+            error_setg(errp, "Postcopy is not yet compatible with multifd");
+            return false;
+        }
     }
 
     if (cap_list[MIGRATION_CAPABILITY_BACKGROUND_SNAPSHOT]) {
-- 
2.40.0