migration/cpr: Add HMP support for cpr-transfer

Currently the cpr-transfer source QEMU instance cannot be driven entirely
via HMP.  The source must use QMP in order to specify both the
main migration channel and the CPR channel.

Extend the HMP migrate command with an optional CPR channel URI. When the
migration mode is cpr-transfer, HMP uses this URI to build a
CPR MigrationChannel in addition to the main migration channel. The new
option is rejected unless the migration mode is cpr-transfer, so existing
HMP migrate usage is unchanged.

For example, source QEMU HMP commands can be something like below. The
"-c unix:/tmp/cpr.sock" is for CPR URI.

(qemu) migrate_set_parameter mode cpr-transfer
(qemu) migrate -c unix:/tmp/cpr.sock tcp:0:50002

Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Dr. David Alan Gilbert <dave@treblig.org>
Acked-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Link: https://lore.kernel.org/r/20260728085903.173265-1-dongli.zhang@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index b04fc4489f..b5eb27467c 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -837,9 +837,11 @@ void hmp_migrate(Monitor *mon, const QDict *qdict)
     bool detach = qdict_get_try_bool(qdict, "detach", false);
     bool resume = qdict_get_try_bool(qdict, "resume", false);
     const char *uri = qdict_get_str(qdict, "uri");
+    const char *uri_cpr = qdict_get_try_str(qdict, "uri-cpr");
     Error *err = NULL;
     g_autoptr(MigrationChannelList) caps = NULL;
     g_autoptr(MigrationChannel) channel = NULL;
+    g_autoptr(MigrationChannel) channel_cpr = NULL;
 
     if (!migrate_uri_parse(uri, &channel, &err)) {
         hmp_handle_error(mon, err);
@@ -847,6 +849,22 @@ void hmp_migrate(Monitor *mon, const QDict *qdict)
     }
     QAPI_LIST_PREPEND(caps, g_steal_pointer(&channel));
 
+    if (uri_cpr) {
+        if (migrate_mode() != MIG_MODE_CPR_TRANSFER) {
+            error_setg(&err, "-c can only be used in cpr-transfer mode");
+            hmp_handle_error(mon, err);
+            return;
+        }
+
+        if (!migrate_uri_parse(uri_cpr, &channel_cpr, &err)) {
+            hmp_handle_error(mon, err);
+            return;
+        }
+
+        channel_cpr->channel_type = MIGRATION_CHANNEL_TYPE_CPR;
+        QAPI_LIST_PREPEND(caps, g_steal_pointer(&channel_cpr));
+    }
+
     qmp_migrate(NULL, true, caps, true, resume, &err);
     if (hmp_handle_error(mon, err)) {
         return;