linux-kernel - Re: [PATCH v7 5/5] vfio: update live migration device status

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Message-ID: <20230126122808.3c0963f2.alex.williamson@redhat.com>
Date:   Thu, 26 Jan 2023 12:28:08 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Longfang Liu <liulongfang@...wei.com>
Cc:     <jgg@...dia.com>, <shameerali.kolothum.thodi@...wei.com>,
        <jonathan.cameron@...wei.com>, <cohuck@...hat.com>,
        <linux-kernel@...r.kernel.org>, <linuxarm@...neuler.org>
Subject: Re: [PATCH v7 5/5] vfio: update live migration device status

On Fri, 20 Jan 2023 11:29:30 +0800
Longfang Liu <liulongfang@...wei.com> wrote:

> migration debugfs needs to perform debug operations based on the
> status of the current device. If the device is not loaded or has
> stopped, debugfs does not allow operations.
> 
> so, after the live migration function is executed and the device is
> turned off, the device no longer needs to be accessed. At this time,
> the status of the device needs to be set to stop.
> 
> Signed-off-by: Longfang Liu <liulongfang@...wei.com>
> ---
>  drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 3 +++
>  drivers/vfio/pci/mlx5/main.c                   | 3 +++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> index 96e2a021a956..bdb9043f88f1 100644
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> @@ -1607,6 +1607,9 @@ static void hisi_acc_vfio_pci_close_device(struct vfio_device *core_vdev)
>  	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(core_vdev);
>  	struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm;
>  
> +	if (core_vdev->mig_ops)
> +		hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_STOP;
> +
>  	iounmap(vf_qm->io_base);
>  	vfio_pci_core_close_device(core_vdev);
>  }
> diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
> index 031ac8cc215d..64b2fe58355a 100644
> --- a/drivers/vfio/pci/mlx5/main.c
> +++ b/drivers/vfio/pci/mlx5/main.c
> @@ -1092,6 +1092,9 @@ static void mlx5vf_pci_close_device(struct vfio_device *core_vdev)
>  	struct mlx5vf_pci_core_device *mvdev = container_of(
>  		core_vdev, struct mlx5vf_pci_core_device, core_device.vdev);
>  
> +	if (mvdev->migrate_cap)
> +		mvdev->mig_state = VFIO_DEVICE_STATE_STOP;
> +
>  	mlx5vf_cmd_close_migratable(mvdev);
>  	vfio_pci_core_close_device(core_vdev);
>  }

It seems prone to issues to manipulate the migration state outside of
the driver state machine.  If the device is closed, shouldn't the
debugfs state interface return -EINVAL?  Thanks,

Alex