[PATCH V1 01/26] migration: cpr helpers

[Steve Sistare <steven.sistare@oracle.com>]

Add the cpr_needed_for_reuse and cpr_resave_fd helpers, for use when
adding cpr support for vfio and iommufd.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 include/migration/cpr.h |  3 +++
 migration/cpr.c         | 21 +++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/migration/cpr.h b/include/migration/cpr.h
index 3a6deb7..faeb0cc 100644
--- a/include/migration/cpr.h
+++ b/include/migration/cpr.h
@@ -18,6 +18,7 @@
 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);
+void cpr_resave_fd(const char *name, int id, int fd);
 
 MigMode cpr_get_incoming_mode(void);
 void cpr_set_incoming_mode(MigMode mode);
@@ -27,6 +28,8 @@ int cpr_state_load(MigrationChannel *channel, Error **errp);
 void cpr_state_close(void);
 struct QIOChannel *cpr_state_ioc(void);
 
+bool cpr_needed_for_reuse(void *opaque);
+
 QEMUFile *cpr_transfer_output(MigrationChannel *channel, Error **errp);
 QEMUFile *cpr_transfer_input(MigrationChannel *channel, Error **errp);
 
diff --git a/migration/cpr.c b/migration/cpr.c
index 584b0b9..e3f27e9 100644
--- a/migration/cpr.c
+++ b/migration/cpr.c
@@ -95,6 +95,21 @@ int cpr_find_fd(const char *name, int id)
     trace_cpr_find_fd(name, id, fd);
     return fd;
 }
+
+void cpr_resave_fd(const char *name, int id, int fd)
+{
+    CprFd *elem = find_fd(&cpr_state.fds, name, id);
+    int old_fd = elem ? elem->fd : -1;
+
+    if (old_fd < 0) {
+        cpr_save_fd(name, id, fd);
+    } else if (old_fd != fd) {
+        error_setg(&error_fatal,
+                   "internal error: cpr fd '%s' id %d value %d "
+                   "already saved with a different value %d",
+                   name, id, fd, old_fd);
+    }
+}
 /*************************************************************************/
 #define CPR_STATE "CprState"
 
@@ -222,3 +237,9 @@ void cpr_state_close(void)
         cpr_state_file = NULL;
     }
 }
+
+bool cpr_needed_for_reuse(void *opaque)
+{
+    MigMode mode = migrate_mode();
+    return mode == MIG_MODE_CPR_TRANSFER;
+}
-- 
1.8.3.1