Re: [PATCH v4 8/9] vfio/migration: Add x-allow-pre-copy VFIO device property

[Cédric Le Goater]

On 5/28/23 16:06, Avihai Horon wrote:
> Add a new VFIO device property x-allow-pre-copy to keep migration
> compatibility to/from older QEMU versions that don't have VFIO pre-copy
> support.
>
> Signed-off-by: Avihai Horon <avihaih@nvidia.com>


Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.

> ---
>   include/hw/vfio/vfio-common.h | 1 +
>   hw/core/machine.c             | 1 +
>   hw/vfio/migration.c           | 3 ++-
>   hw/vfio/pci.c                 | 2 ++
>   4 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 1db901c194..a53ecbe2e0 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -146,6 +146,7 @@ typedef struct VFIODevice {
>       VFIOMigration *migration;
>       Error *migration_blocker;
>       OnOffAuto pre_copy_dirty_page_tracking;
> +    bool allow_pre_copy;
>       bool dirty_pages_supported;
>       bool dirty_tracking;
>   } VFIODevice;
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 1000406211..64ac3fe38e 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -41,6 +41,7 @@
>   
>   GlobalProperty hw_compat_8_0[] = {
>       { "migration", "multifd-flush-after-each-section", "on"},
> +    { "vfio-pci", "x-allow-pre-copy", "false" },
>   };
>   const size_t hw_compat_8_0_len = G_N_ELEMENTS(hw_compat_8_0);
>   
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index d8f6a22ae1..cb6923ed3f 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -323,7 +323,8 @@ static bool vfio_precopy_supported(VFIODevice *vbasedev)
>   {
>       VFIOMigration *migration = vbasedev->migration;
>   
> -    return migration->mig_flags & VFIO_MIGRATION_PRE_COPY;
> +    return vbasedev->allow_pre_copy &&
> +           migration->mig_flags & VFIO_MIGRATION_PRE_COPY;
>   }
>   
>   /* ---------------------------------------------------------------------- */
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 73874a94de..c69813af7f 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3335,6 +3335,8 @@ static Property vfio_pci_dev_properties[] = {
>       DEFINE_PROP_ON_OFF_AUTO("x-pre-copy-dirty-page-tracking", VFIOPCIDevice,
>                               vbasedev.pre_copy_dirty_page_tracking,
>                               ON_OFF_AUTO_ON),
> +    DEFINE_PROP_BOOL("x-allow-pre-copy", VFIOPCIDevice,
> +                     vbasedev.allow_pre_copy, true),
>       DEFINE_PROP_ON_OFF_AUTO("display", VFIOPCIDevice,
>                               display, ON_OFF_AUTO_OFF),
>       DEFINE_PROP_UINT32("xres", VFIOPCIDevice, display_xres, 0),