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

["Cédric Le Goater" <clg@redhat.com>]

On 11/17/24 20:20, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@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.szmigiero@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;
>