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 74a79bdf61f9..e2ac1db96002 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3346,6 +3346,8 @@ 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),
@@ -3367,6 +3369,8 @@ 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_BOOL("migration-events", VFIOPCIDevice,
                      vbasedev.migration_events, false),
     DEFINE_PROP_BOOL("x-no-mmap", VFIOPCIDevice, vbasedev.no_mmap, false),
@@ -3464,6 +3468,9 @@ 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 aa8476a859a6..bc85891d8fff 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -132,6 +132,7 @@ typedef struct VFIODevice {
     bool no_mmap;
     bool ram_block_discard_allowed;
     OnOffAuto enable_migration;
+    bool migration_multifd_transfer;
     bool migration_events;
     VFIODeviceOps *ops;
     unsigned int num_irqs;