migration: check RDMA and capabilities are compatible on both sides

Depending on the order of starting RDMA and setting capability,
they can be categorized into the following scenarios:
Source:
 S1: [set capabilities] -> [Start RDMA outgoing]
Destination:
 D1: [set capabilities] -> [Start RDMA incoming]
 D2: [Start RDMA incoming] -> [set capabilities]

Previously, compatibility between RDMA and capabilities was verified only
in scenario D1, potentially causing migration failures in other situations.

For scenarios S1 and D1, we can seamlessly incorporate
migration_transport_compatible() to address compatibility between
channels and capabilities vs transport.

For scenario D2, ensure compatibility within migrate_caps_check().

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Message-ID: <20250305062825.772629-3-lizhijian@fujitsu.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>

1 files changed, 21 insertions, 0 deletions

diff --git a/migration/options.c b/migration/options.c
index b0ac2ea408..1f3602839d 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -448,6 +448,20 @@ static bool migrate_incoming_started(void)
     return !!migration_incoming_get_current()->transport_data;
 }
 
+bool migrate_rdma_caps_check(bool *caps, Error **errp)
+{
+    if (caps[MIGRATION_CAPABILITY_XBZRLE]) {
+        error_setg(errp, "RDMA and XBZRLE can't be used together");
+        return false;
+    }
+    if (caps[MIGRATION_CAPABILITY_MULTIFD]) {
+        error_setg(errp, "RDMA and multifd can't be used together");
+        return false;
+    }
+
+    return true;
+}
+
 /**
  * @migration_caps_check - check capability compatibility
  *
@@ -611,6 +625,13 @@ bool migrate_caps_check(bool *old_caps, bool *new_caps, Error **errp)
         }
     }
 
+    /*
+     * On destination side, check the cases that capability is being set
+     * after incoming thread has started.
+     */
+    if (migrate_rdma() && !migrate_rdma_caps_check(new_caps, errp)) {
+        return false;
+    }
     return true;
 }