migration: cpr-state

CPR must save state that is needed after QEMU is restarted, when devices
are realized.  Thus the extra state cannot be saved in the migration
channel, as objects must already exist before that channel can be loaded.
Instead, define auxilliary state structures and vmstate descriptions, not
associated with any registered object, and serialize the aux state to a
cpr-specific channel in cpr_state_save.  Deserialize in cpr_state_load
after QEMU restarts, before devices are realized.

Provide accessors for clients to register file descriptors for saving.
The mechanism for passing the fd's to the new process will be specific
to each migration mode, and added in subsequent patches.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-8-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>

1 files changed, 25 insertions, 0 deletions

diff --git a/include/migration/cpr.h b/include/migration/cpr.h
new file mode 100644
index 0000000000..d9364f7d1f
--- /dev/null
+++ b/include/migration/cpr.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2021, 2024 Oracle and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef MIGRATION_CPR_H
+#define MIGRATION_CPR_H
+
+#include "qapi/qapi-types-migration.h"
+
+#define QEMU_CPR_FILE_MAGIC     0x51435052
+#define QEMU_CPR_FILE_VERSION   0x00000001
+
+void cpr_save_fd(const char *name, int id, int fd);
+void cpr_delete_fd(const char *name, int id);
+int cpr_find_fd(const char *name, int id);
+
+int cpr_state_save(MigrationChannel *channel, Error **errp);
+int cpr_state_load(MigrationChannel *channel, Error **errp);
+void cpr_state_close(void);
+struct QIOChannel *cpr_state_ioc(void);
+
+#endif