migration: Move migrate_allow_multifd and helpers into migration.c

This variable, along with its helpers, is used to detect whether multiple
channel will be supported for migration.  In follow up patches, there'll be
other capability that requires multi-channels.  Hence move it outside multifd
specific code and make it public.  Meanwhile rename it from "multifd" to
"multi_channels" to show its real meaning.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220331150857.74406-5-peterx@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migration/migration.c

@@ -180,6 +180,18 @@ static int migration_maybe_pause(MigrationState *s,
                                  int new_state);
 static void migrate_fd_cancel(MigrationState *s);
 
+static bool migrate_allow_multi_channels = true;
+
+void migrate_protocol_allow_multi_channels(bool allow)
+{
+    migrate_allow_multi_channels = allow;
+}
+
+bool migrate_multi_channels_is_allowed(void)
+{
+    return migrate_allow_multi_channels;
+}
+
 static gint page_request_addr_cmp(gconstpointer ap, gconstpointer bp)
 {
     uintptr_t a = (uintptr_t) ap, b = (uintptr_t) bp;
@@ -469,12 +481,12 @@ static void qemu_start_incoming_migration(const char *uri, Error **errp)
 {
     const char *p = NULL;
 
-    migrate_protocol_allow_multifd(false); /* reset it anyway */
+    migrate_protocol_allow_multi_channels(false); /* reset it anyway */
     qapi_event_send_migration(MIGRATION_STATUS_SETUP);
     if (strstart(uri, "tcp:", &p) ||
         strstart(uri, "unix:", NULL) ||
         strstart(uri, "vsock:", NULL)) {
-        migrate_protocol_allow_multifd(true);
+        migrate_protocol_allow_multi_channels(true);
         socket_start_incoming_migration(p ? p : uri, errp);
 #ifdef CONFIG_RDMA
     } else if (strstart(uri, "rdma:", &p)) {
@@ -1261,7 +1273,7 @@ static bool migrate_caps_check(bool *cap_list,
 
     /* incoming side only */
     if (runstate_check(RUN_STATE_INMIGRATE) &&
-        !migrate_multifd_is_allowed() &&
+        !migrate_multi_channels_is_allowed() &&
         cap_list[MIGRATION_CAPABILITY_MULTIFD]) {
         error_setg(errp, "multifd is not supported by current protocol");
         return false;
@@ -2322,11 +2334,11 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
         }
     }
 
-    migrate_protocol_allow_multifd(false);
+    migrate_protocol_allow_multi_channels(false);
     if (strstart(uri, "tcp:", &p) ||
         strstart(uri, "unix:", NULL) ||
         strstart(uri, "vsock:", NULL)) {
-        migrate_protocol_allow_multifd(true);
+        migrate_protocol_allow_multi_channels(true);
         socket_start_outgoing_migration(s, p ? p : uri, &local_err);
 #ifdef CONFIG_RDMA
     } else if (strstart(uri, "rdma:", &p)) {

migration/migration.h

@@ -430,4 +430,7 @@ void migration_cancel(const Error *error);
 void populate_vfio_info(MigrationInfo *info);
 void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page);
 
+bool migrate_multi_channels_is_allowed(void);
+void migrate_protocol_allow_multi_channels(bool allow);
+
 #endif

migration/multifd.c

@@ -517,7 +517,7 @@ void multifd_save_cleanup(void)
 {
     int i;
 
-    if (!migrate_use_multifd() || !migrate_multifd_is_allowed()) {
+    if (!migrate_use_multifd() || !migrate_multi_channels_is_allowed()) {
         return;
     }
     multifd_send_terminate_threads(NULL);
@@ -857,17 +857,6 @@ static void multifd_new_send_channel_async(QIOTask *task, gpointer opaque)
     multifd_new_send_channel_cleanup(p, sioc, local_err);
 }
 
-static bool migrate_allow_multifd = true;
-void migrate_protocol_allow_multifd(bool allow)
-{
-    migrate_allow_multifd = allow;
-}
-
-bool migrate_multifd_is_allowed(void)
-{
-    return migrate_allow_multifd;
-}
-
 int multifd_save_setup(Error **errp)
 {
     int thread_count;
@@ -877,7 +866,7 @@ int multifd_save_setup(Error **errp)
     if (!migrate_use_multifd()) {
         return 0;
     }
-    if (!migrate_multifd_is_allowed()) {
+    if (!migrate_multi_channels_is_allowed()) {
         error_setg(errp, "multifd is not supported by current protocol");
         return -1;
     }
@@ -976,7 +965,7 @@ int multifd_load_cleanup(Error **errp)
 {
     int i;
 
-    if (!migrate_use_multifd() || !migrate_multifd_is_allowed()) {
+    if (!migrate_use_multifd() || !migrate_multi_channels_is_allowed()) {
         return 0;
     }
     multifd_recv_terminate_threads(NULL);
@@ -1125,7 +1114,7 @@ int multifd_load_setup(Error **errp)
     if (!migrate_use_multifd()) {
         return 0;
     }
-    if (!migrate_multifd_is_allowed()) {
+    if (!migrate_multi_channels_is_allowed()) {
         error_setg(errp, "multifd is not supported by current protocol");
         return -1;
     }

migration/multifd.h

@@ -13,8 +13,6 @@
 #ifndef QEMU_MIGRATION_MULTIFD_H
 #define QEMU_MIGRATION_MULTIFD_H
 
-bool migrate_multifd_is_allowed(void);
-void migrate_protocol_allow_multifd(bool allow);
 int multifd_save_setup(Error **errp);
 void multifd_save_cleanup(void);
 int multifd_load_setup(Error **errp);