Subject: Re: [PATCH v13 05/13] vdpa: Add reset callback in vdpa_config_ops

From: "Michael S. Tsirkin" <[email-masked]>
Date: Mon, 6 Sep 2021 01:55:56 -0400

On Tue, Aug 31, 2021 at 06:36:26PM +0800, Xie Yongji wrote:
> This adds a new callback to support device specific reset
> behavior. The vdpa bus driver will call the reset function
> instead of setting status to zero during resetting.
> 
> Signed-off-by: Xie Yongji <[email-masked]>

This does gloss over a significant change though:

> ---
> @@ -348,12 +352,12 @@ static inline struct device *vdpa_get_dma_dev(struct vdpa_device *vdev)
>  	return vdev->dma_dev;
>  }
>  
> -static inline void vdpa_reset(struct vdpa_device *vdev)
> +static inline int vdpa_reset(struct vdpa_device *vdev)
>  {
>  	const struct vdpa_config_ops *ops = vdev->config;
>  
>  	vdev->features_valid = false;
> -	ops->set_status(vdev, 0);
> +	return ops->reset(vdev);
>  }
>  
>  static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)

Unfortunately this breaks virtio_vdpa:

static void virtio_vdpa_reset(struct virtio_device *vdev)
{
        struct vdpa_device *vdpa = vd_get_vdpa(vdev);

        vdpa_reset(vdpa);
}

and there's no easy way to fix this, kernel can't recover
from a reset failure e.g. during driver unbind.

Find a way to disable virtio_vdpa for now?

> -- 
> 2.11.0