netdev - Re: [PATCH mlx5-next 1/5] vfio/mlx5: Reorganize the VF is migratable code

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Date:   Wed, 4 May 2022 14:13:04 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Yishai Hadas <yishaih@...dia.com>
Cc:     <jgg@...dia.com>, <saeedm@...dia.com>, <kvm@...r.kernel.org>,
        <netdev@...r.kernel.org>, <kuba@...nel.org>, <leonro@...dia.com>,
        <maorg@...dia.com>, <cohuck@...hat.com>
Subject: Re: [PATCH mlx5-next 1/5] vfio/mlx5: Reorganize the VF is
 migratable code

On Wed, 27 Apr 2022 12:31:16 +0300
Yishai Hadas <yishaih@...dia.com> wrote:

> Reorganize the VF is migratable code to be in a separate function, next
> patches from the series may use this.
> 
> Signed-off-by: Yishai Hadas <yishaih@...dia.com>
> Signed-off-by: Leon Romanovsky <leonro@...dia.com>
> ---
>  drivers/vfio/pci/mlx5/cmd.c  | 18 ++++++++++++++++++
>  drivers/vfio/pci/mlx5/cmd.h  |  1 +
>  drivers/vfio/pci/mlx5/main.c | 22 +++++++---------------
>  3 files changed, 26 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
> index 5c9f9218cc1d..d608b8167f58 100644
> --- a/drivers/vfio/pci/mlx5/cmd.c
> +++ b/drivers/vfio/pci/mlx5/cmd.c
> @@ -71,6 +71,24 @@ int mlx5vf_cmd_query_vhca_migration_state(struct pci_dev *pdev, u16 vhca_id,
>  	return ret;
>  }
>  
> +bool mlx5vf_cmd_is_migratable(struct pci_dev *pdev)
> +{
> +	struct mlx5_core_dev *mdev = mlx5_vf_get_core_dev(pdev);
> +	bool migratable = false;
> +
> +	if (!mdev)
> +		return false;
> +
> +	if (!MLX5_CAP_GEN(mdev, migration))
> +		goto end;
> +
> +	migratable = true;
> +
> +end:
> +	mlx5_vf_put_core_dev(mdev);
> +	return migratable;
> +}

This goto seems unnecessary, couldn't it instead be written:

{
	struct mlx5_core_dev *mdev = mlx5_vf_get_core_dev(pdev);
	boot migratable = true;

	if (!mdev)
		return false;

	if (!MLX5_CAP_GEN(mdev, migration))
		migratable = false;

	mlx5_vf_put_core_mdev(mdev);
	return migratable;
}

Thanks,
Alex

> +
>  int mlx5vf_cmd_get_vhca_id(struct pci_dev *pdev, u16 function_id, u16 *vhca_id)
>  {
>  	struct mlx5_core_dev *mdev = mlx5_vf_get_core_dev(pdev);
> diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h
> index 1392a11a9cc0..2da6a1c0ec5c 100644
> --- a/drivers/vfio/pci/mlx5/cmd.h
> +++ b/drivers/vfio/pci/mlx5/cmd.h
> @@ -29,6 +29,7 @@ int mlx5vf_cmd_resume_vhca(struct pci_dev *pdev, u16 vhca_id, u16 op_mod);
>  int mlx5vf_cmd_query_vhca_migration_state(struct pci_dev *pdev, u16 vhca_id,
>  					  size_t *state_size);
>  int mlx5vf_cmd_get_vhca_id(struct pci_dev *pdev, u16 function_id, u16 *vhca_id);
> +bool mlx5vf_cmd_is_migratable(struct pci_dev *pdev);
>  int mlx5vf_cmd_save_vhca_state(struct pci_dev *pdev, u16 vhca_id,
>  			       struct mlx5_vf_migration_file *migf);
>  int mlx5vf_cmd_load_vhca_state(struct pci_dev *pdev, u16 vhca_id,
> diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
> index bbec5d288fee..2578f61eaeae 100644
> --- a/drivers/vfio/pci/mlx5/main.c
> +++ b/drivers/vfio/pci/mlx5/main.c
> @@ -597,21 +597,13 @@ static int mlx5vf_pci_probe(struct pci_dev *pdev,
>  		return -ENOMEM;
>  	vfio_pci_core_init_device(&mvdev->core_device, pdev, &mlx5vf_pci_ops);
>  
> -	if (pdev->is_virtfn) {
> -		struct mlx5_core_dev *mdev =
> -			mlx5_vf_get_core_dev(pdev);
> -
> -		if (mdev) {
> -			if (MLX5_CAP_GEN(mdev, migration)) {
> -				mvdev->migrate_cap = 1;
> -				mvdev->core_device.vdev.migration_flags =
> -					VFIO_MIGRATION_STOP_COPY |
> -					VFIO_MIGRATION_P2P;
> -				mutex_init(&mvdev->state_mutex);
> -				spin_lock_init(&mvdev->reset_lock);
> -			}
> -			mlx5_vf_put_core_dev(mdev);
> -		}
> +	if (pdev->is_virtfn && mlx5vf_cmd_is_migratable(pdev)) {
> +		mvdev->migrate_cap = 1;
> +		mvdev->core_device.vdev.migration_flags =
> +			VFIO_MIGRATION_STOP_COPY |
> +			VFIO_MIGRATION_P2P;
> +		mutex_init(&mvdev->state_mutex);
> +		spin_lock_init(&mvdev->reset_lock);
>  	}
>  
>  	ret = vfio_pci_core_register_device(&mvdev->core_device);