Re: [PATCH v6 13/15] s390/vfio-ap: Callback to get the size of data to be migrated during guest migration

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Logic duplication for calculating the configuration size.
--

--- Patch [13]: [PATCH v6 13/15] s390/vfio-ap: Callback to get the size of data to be migrated during guest migration ---
commit f0e78a002713b19ca67967cef71fbd73dea59ee7
Author: Anthony Krowiak <akrowiak@linux.ibm.com>

s390/vfio-ap: Callback to get the size of data to be migrated during guest migration

This commit adds the mandatory migration_get_data_size callback for VFIO
migration support on the s390 vfio_ap driver. The callback calculates the
estimated data length required to migrate the device's internal state.

> diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
> index 1c385908fc39b..8379cf8bbce89 100644
> --- a/drivers/s390/crypto/vfio_ap_migration.c
> +++ b/drivers/s390/crypto/vfio_ap_migration.c
> @@ -1392,7 +1392,18 @@ static int vfio_ap_get_state(struct vfio_device *vdev,
>  static int vfio_ap_get_data_size(struct vfio_device *vdev,
>  				 unsigned long *stop_copy_length)
>  {
> -	return -EOPNOTSUPP;
> +	struct ap_matrix_mdev *matrix_mdev;
> +	size_t qinfo_sz;
> +	int num_queues;
> +
> +	mutex_lock(&matrix_dev->mdevs_lock);
> +	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
> +	num_queues = vfio_ap_mdev_get_num_queues(&matrix_mdev->shadow_apcb);
> +	qinfo_sz = num_queues * sizeof(struct vfio_ap_queue_info);
> +	*stop_copy_length = qinfo_sz + sizeof(struct vfio_ap_config);

[Severity: Low]
Does this code manually duplicate the size calculation logic already present 
in the existing static helper vfio_ap_config_size() within this same file?

Additionally, since struct vfio_ap_config uses a trailing flexible array 
member for qinfo, would it be better to use the standard struct_size() macro 
to compute the total length instead of manual multiplication and addition?

> +	mutex_unlock(&matrix_dev->mdevs_lock);
> +
> +	return 0;
>  }

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260727173239.2420754-1-akrowiak@linux.ibm.com?part=13