[PATCH QEMU HCI-8.1 v6 24/34] migration/cpr: add cpr_is_in_progress()

[Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>]

cpr_incoming_needed() only looks at the migration mode.  That's fine for
vmstate .needed callbacks, which run during a save or load.  But code that
runs at any time, e.g. VM state change handlers, can't tell from it
whether a CPR migration is actually going on: on the source the mode is
just a parameter, set by migrate-set-parameters whether or not a migrate
follows.

Add cpr_is_in_progress(), which is true on the target until the incoming
migration is done, and on the source only while the outgoing one runs.

Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 include/migration/cpr.h |  1 +
 migration/cpr.c         | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/migration/cpr.h b/include/migration/cpr.h
index 4dd397a7c13..e73c5da1d9c 100644
--- a/include/migration/cpr.h
+++ b/include/migration/cpr.h
@@ -64,6 +64,7 @@ MigMode cpr_get_incoming_mode(void);
 void cpr_set_incoming_mode(MigMode mode);
 bool cpr_is_incoming(void);
 bool cpr_exec_is_incoming(void);
+bool cpr_is_in_progress(void);
 
 bool cpr_state_save(MigrationChannel *channel, Error **errp);
 int cpr_state_load(MigrationChannel *channel, Error **errp);
diff --git a/migration/cpr.c b/migration/cpr.c
index a149e790c10..3ea5d86bab4 100644
--- a/migration/cpr.c
+++ b/migration/cpr.c
@@ -549,6 +549,28 @@ bool cpr_exec_is_incoming(void)
     return incoming_mode == MIG_MODE_CPR_EXEC;
 }
 
+bool cpr_is_in_progress(void)
+{
+    /* The incoming mode on the target, the 'mode' parameter on the source */
+    MigMode mode = migrate_mode();
+
+    if (mode != MIG_MODE_CPR_TRANSFER && mode != MIG_MODE_CPR_EXEC) {
+        return false;
+    }
+
+    /* Target: the incoming mode is set until the incoming migration is done */
+    if (cpr_is_incoming()) {
+        return true;
+    }
+
+    /*
+     * Source: the parameter alone means nothing, it may just have been set.
+     * An outgoing CPR migration has the CPR state open, from
+     * cpr_state_save() to cpr_state_close().
+     */
+    return cpr_state_file != NULL;
+}
+
 bool cpr_state_save(MigrationChannel *channel, Error **errp)
 {
     int ret;

-- 
2.47.1