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

[Cédric Le Goater]

On 11/17/24 20:20, Maciej S. Szmigiero wrote:

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

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 <maciej.szmigi...@oracle.com>
---
  hw/core/machine.c             | 1 +
  hw/vfio/pci.c                 | 9 +++++++++
  include/hw/vfio/vfio-common.h | 1 +
  3 files changed, 11 insertions(+)

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" },

Could you please move the compat changes into their own patch ?
It's easier for backports

  };
  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),

What are you trying to do that DEFINE_PROP_ON_OFF_AUTO() can not satisfy ?


Thanks,

C.

      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;