On Sun, Feb 20 2022, Yishai Hadas <yishaih@xxxxxxxxxx> wrote:
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index ca69516f869d..3bbadcdbc9c8 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -56,6 +56,14 @@ struct vfio_device {
> * match, -errno for abort (ex. match with insufficient or incorrect
> * additional args)
> * @device_feature: Fill in the VFIO_DEVICE_FEATURE ioctl
> + * @migration_set_state: Optional callback to change the migration state for
> + * devices that support migration. The returned FD is used for data
> + * transfer according to the FSM definition. The driver is responsible
> + * to ensure that FD reaches end of stream or error whenever the
> + * migration FSM leaves a data transfer state or before close_device()
> + * returns.
> + * @migration_get_state: Optional callback to get the migration state for
> + * devices that support migration.
Nit: I'd add "mandatory for VFIO_DEVICE_FEATURE_MIGRATION migration
support" to both descriptions to be a bit more explicit.
(...)
> +/*
> + * Indicates the device can support the migration API through
> + * VFIO_DEVICE_FEATURE_MIG_DEVICE_STATE. If present flags must be non-zero and
> + * VFIO_DEVICE_FEATURE_MIG_DEVICE_STATE is supported. The RUNNING and
I'm having trouble parsing this. I think what it tries to say is that at
least one of the flags defined below must be set?
> + * ERROR states are always supported if this GET succeeds.
What about the following instead:
"Indicates device support for the migration API through
VFIO_DEVICE_FEATURE_MIG_DEVICE_STATE. If present, the RUNNING and ERROR
states are always supported. Support for additional states is indicated
via the flags field; at least one of the flags defined below must be
set."
> + *
> + * VFIO_MIGRATION_STOP_COPY means that STOP, STOP_COPY and
> + * RESUMING are supported.
> + */
> +struct vfio_device_feature_migration {
> + __aligned_u64 flags;
> +#define VFIO_MIGRATION_STOP_COPY (1 << 0)
> +};
