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.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
 include/migration/misc.h         | 1 +
 migration/multifd-device-state.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/include/migration/misc.h b/include/migration/misc.h
index bd3b725fa0b7..273ebfca6256 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -121,5 +121,6 @@ bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
 /* migration/multifd-device-state.c */
 bool multifd_queue_device_state(char *idstr, uint32_t instance_id,
                                 char *data, size_t len);
+bool multifd_device_state_supported(void);
 
 #endif
diff --git a/migration/multifd-device-state.c b/migration/multifd-device-state.c
index 64d8ca180167..3097ffa31025 100644
--- a/migration/multifd-device-state.c
+++ b/migration/multifd-device-state.c
@@ -13,6 +13,7 @@
 #include "qemu/lockable.h"
 #include "migration/misc.h"
 #include "multifd.h"
+#include "options.h"
 
 static struct {
     QemuMutex queue_job_mutex;
@@ -111,3 +112,9 @@ bool multifd_queue_device_state(char *idstr, uint32_t instance_id,
 
     return true;
 }
+
+bool multifd_device_state_supported(void)
+{
+    return migrate_multifd() && !migrate_mapped_ram() &&
+        migrate_multifd_compression() == MULTIFD_COMPRESSION_NONE;
+}