netdev - Re: [PATCH v10 05/17] vhost-vdpa: Fail the vhost_vdpa_set

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Date:   Tue, 3 Aug 2021 16:10:46 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Xie Yongji <xieyongji@...edance.com>, mst@...hat.com,
        stefanha@...hat.com, sgarzare@...hat.com, parav@...dia.com,
        hch@...radead.org, christian.brauner@...onical.com,
        rdunlap@...radead.org, willy@...radead.org,
        viro@...iv.linux.org.uk, axboe@...nel.dk, bcrl@...ck.org,
        corbet@....net, mika.penttila@...tfour.com,
        dan.carpenter@...cle.com, joro@...tes.org,
        gregkh@...uxfoundation.org, zhe.he@...driver.com,
        xiaodong.liu@...el.com, joe@...ches.com
Cc:     songmuchun@...edance.com,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        kvm@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 05/17] vhost-vdpa: Fail the vhost_vdpa_set_status() on
 reset failure


在 2021/7/29 下午3:34, Xie Yongji 写道:
> Re-read the device status to ensure it's set to zero during
> resetting. Otherwise, fail the vhost_vdpa_set_status() after timeout.
>
> Signed-off-by: Xie Yongji <xieyongji@...edance.com>
> ---
>   drivers/vhost/vdpa.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index b07aa161f7ad..dd05c1e1133c 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -157,7 +157,7 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
>   	struct vdpa_device *vdpa = v->vdpa;
>   	const struct vdpa_config_ops *ops = vdpa->config;
>   	u8 status, status_old;
> -	int nvqs = v->nvqs;
> +	int timeout = 0, nvqs = v->nvqs;
>   	u16 i;
>   
>   	if (copy_from_user(&status, statusp, sizeof(status)))
> @@ -173,6 +173,15 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
>   		return -EINVAL;
>   
>   	ops->set_status(vdpa, status);
> +	if (status == 0) {
> +		while (ops->get_status(vdpa)) {
> +			timeout += 20;
> +			if (timeout > VDPA_RESET_TIMEOUT_MS)
> +				return -EIO;
> +
> +			msleep(20);
> +		}


Spec has introduced the reset a one of the basic facility. And consider 
we differ reset here.

This makes me think if it's better to introduce a dedicated vdpa ops for 
reset?

Thanks


> +	}
>   
>   	if ((status & VIRTIO_CONFIG_S_DRIVER_OK) && !(status_old & VIRTIO_CONFIG_S_DRIVER_OK))
>   		for (i = 0; i < nvqs; i++)