[v3,19/24] vfio/migration: Add x-migration-multifd-transfer VFIO property

Commit Message

Maciej S. Szmigiero Nov. 17, 2024, 7:20 p.m. UTC

From: "Maciej S. Szmigiero" <[e-mail]>

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

It defaults to AUTO, which means that VFIO device state transfer via
multifd channels is attempted in configurations that otherwise support it.

Signed-off-by: Maciej S. Szmigiero <[e-mail]>
---
 hw/core/machine.c             | 1 +
 hw/vfio/pci.c                 | 9 +++++++++
 include/hw/vfio/vfio-common.h | 1 +
 3 files changed, 11 insertions(+)

Patch

diff --git a/hw/core/machine.c b/hw/core/machine.c
index ed8d39fd769f..fda0f8280edd 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -39,6 +39,7 @@ 
 GlobalProperty hw_compat_9_1[] = {
     { TYPE_PCI_DEVICE, "x-pcie-ext-tag", "false" },
     { "migration", "send-switchover-start", "off"},
+    { "vfio-pci", "x-migration-multifd-transfer", "off" },
 };
 const size_t hw_compat_9_1_len = G_N_ELEMENTS(hw_compat_9_1);
 
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 14bcc725c301..9d547cb5cdff 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_on_off_auto_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 +3380,10 @@  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_on_off_auto_mutable, OnOffAuto,
+                .set_default = true, .defval.i = ON_OFF_AUTO_AUTO),
     DEFINE_PROP_BOOL("migration-events", VFIOPCIDevice,
                      vbasedev.migration_events, false),
     DEFINE_PROP_BOOL("x-no-mmap", VFIOPCIDevice, vbasedev.no_mmap, false),
@@ -3475,6 +3481,9 @@  static const TypeInfo vfio_pci_nohotplug_dev_info = {
 
 static void register_vfio_pci_dev_type(void)
 {
+    qdev_prop_on_off_auto_mutable = qdev_prop_on_off_auto;
+    qdev_prop_on_off_auto_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 246250ed8b75..b1c03a82eec8 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -134,6 +134,7 @@  typedef struct VFIODevice {
     bool no_mmap;
     bool ram_block_discard_allowed;
     OnOffAuto enable_migration;
+    OnOffAuto migration_multifd_transfer;
     bool migration_events;
     VFIODeviceOps *ops;
     unsigned int num_irqs;