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

This property allows configuring at runtime whether to send the
particular device state via multifd channels when live migrating that
device.

It is ignored on the receive side and defaults to "false" for bit stream
compatibility with older QEMU versions.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
 hw/vfio/pci.c                 | 7 +++++++
 include/hw/vfio/vfio-common.h | 1 +
 2 files changed, 8 insertions(+)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 08cb56d27a05..b68f08ba8a4f 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3354,6 +3354,8 @@ static void vfio_instance_init(Object *obj)
     pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
 }
 
+static PropertyInfo qdev_prop_bool_mutable;
+
 static Property vfio_pci_dev_properties[] = {
     DEFINE_PROP_PCI_HOST_DEVADDR("host", VFIOPCIDevice, host),
     DEFINE_PROP_UUID_NODEFAULT("vf-token", VFIOPCIDevice, vf_token),
@@ -3378,6 +3380,8 @@ static Property vfio_pci_dev_properties[] = {
                     VFIO_FEATURE_ENABLE_IGD_OPREGION_BIT, false),
     DEFINE_PROP_ON_OFF_AUTO("enable-migration", VFIOPCIDevice,
                             vbasedev.enable_migration, ON_OFF_AUTO_AUTO),
+    DEFINE_PROP("x-migration-multifd-transfer", VFIOPCIDevice,
+                vbasedev.migration_multifd_transfer, qdev_prop_bool_mutable, bool),
     DEFINE_PROP_UINT64("x-migration-max-queued-buffers", VFIOPCIDevice,
                        vbasedev.migration_max_queued_buffers, UINT64_MAX),
     DEFINE_PROP_BOOL("migration-events", VFIOPCIDevice,
@@ -3477,6 +3481,9 @@ static const TypeInfo vfio_pci_nohotplug_dev_info = {
 
 static void register_vfio_pci_dev_type(void)
 {
+    qdev_prop_bool_mutable = qdev_prop_bool;
+    qdev_prop_bool_mutable.realized_set_allowed = true;
+
     type_register_static(&vfio_pci_dev_info);
     type_register_static(&vfio_pci_nohotplug_dev_info);
 }
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index ba5b9464e79a..fe05acb9a5d1 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -149,6 +149,7 @@ typedef struct VFIODevice {
     bool no_mmap;
     bool ram_block_discard_allowed;
     OnOffAuto enable_migration;
+    bool migration_multifd_transfer;
     bool migration_events;
     uint64_t migration_max_queued_buffers;
     VFIODeviceOps *ops;