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Date:   Mon, 6 Sep 2021 01:54:46 -0400
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Xie Yongji <xieyongji@bytedance.com>
Cc:     jasowang@redhat.com, stefanha@redhat.com, sgarzare@redhat.com,
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Subject: Re: [PATCH v12 05/13] vdpa: Add reset callback in vdpa_config_ops
Message-ID: <20210906015243-mutt-send-email-mst@kernel.org>
References: <20210830141737.181-1-xieyongji@bytedance.com>
 <20210830141737.181-6-xieyongji@bytedance.com>
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In-Reply-To: <20210830141737.181-6-xieyongji@bytedance.com>
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On Mon, Aug 30, 2021 at 10:17:29PM +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 <xieyongji@bytedance.com>

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