From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>

Since device state transfer via multifd channels requires multifd
channels with packets and is currently not compatible with multifd
compression add an appropriate query function so device can learn
whether it can actually make use of it.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
 include/migration/misc.h | 1 +
 migration/multifd.c      | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/include/migration/misc.h b/include/migration/misc.h
index abf6f33eeae8..4f3de2f23819 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -112,6 +112,7 @@ bool migration_in_bg_snapshot(void);
 void dirty_bitmap_mig_init(void);
 
 /* migration/multifd.c */
+bool migration_has_device_state_support(void);
 int multifd_queue_device_state(char *idstr, uint32_t instance_id,
                                char *data, size_t len);
 
diff --git a/migration/multifd.c b/migration/multifd.c
index 6a7e5d659925..e5f7021465ec 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -804,6 +804,12 @@ retry:
     return true;
 }
 
+bool migration_has_device_state_support(void)
+{
+    return migrate_multifd() && !migrate_mapped_ram() &&
+        migrate_multifd_compression() == MULTIFD_COMPRESSION_NONE;
+}
+
 int multifd_queue_device_state(char *idstr, uint32_t instance_id,
                                char *data, size_t len)
 {