[PATCH v2 13/17] migration/multifd: Add migration_has_device_state_support()

[Maciej S. Szmigiero]

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-device-state.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/include/migration/misc.h b/include/migration/misc.h
index 7266b1b77d1f..189de6d02ad6 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -114,5 +114,6 @@ void dirty_bitmap_mig_init(void);
 /* migration/multifd-device-state.c */
 bool multifd_queue_device_state(char *idstr, uint32_t instance_id,
                                 char *data, size_t len);
+bool migration_has_device_state_support(void);
 
 #endif
diff --git a/migration/multifd-device-state.c b/migration/multifd-device-state.c
index c9b44f0b5ab9..7b34fe736c7f 100644
--- a/migration/multifd-device-state.c
+++ b/migration/multifd-device-state.c
@@ -11,6 +11,7 @@
 #include "qemu/lockable.h"
 #include "migration/misc.h"
 #include "multifd.h"
+#include "options.h"
 
 static QemuMutex queue_job_mutex;
 
@@ -97,3 +98,9 @@ bool multifd_queue_device_state(char *idstr, uint32_t 
instance_id,
 
     return true;
 }
+
+bool migration_has_device_state_support(void)
+{
+    return migrate_multifd() && !migrate_mapped_ram() &&
+        migrate_multifd_compression() == MULTIFD_COMPRESSION_NONE;
+}