Re: [RFC v4 02/11] vhost-vdpa: protect concurrent access to vhost device iotlb

From: Jason Wang <jasowang@redhat.com>
To: Xie Yongji <xieyongji@bytedance.com>,
	mst@redhat.com, stefanha@redhat.com, sgarzare@redhat.com,
	parav@nvidia.com, bob.liu@oracle.com, hch@infradead.org,
	rdunlap@infradead.org, willy@infradead.org,
	viro@zeniv.linux.org.uk, axboe@kernel.dk, bcrl@kvack.org,
	corbet@lwn.net
Cc: virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, kvm@vger.kernel.org, linux-aio@kvack.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [RFC v4 02/11] vhost-vdpa: protect concurrent access to vhost device iotlb
Date: Tue, 2 Mar 2021 14:47:21 +0800	[thread overview]
Message-ID: <a170e0ec-f0cf-e23f-0ca7-e8a5bfd1cf31@redhat.com> (raw)
In-Reply-To: <20210223115048.435-3-xieyongji@bytedance.com>

On 2021/2/23 7:50 下午, Xie Yongji wrote:
> Use vhost_dev->mutex to protect vhost device iotlb from
> concurrent access.
>
> Fixes: 4c8cf318("vhost: introduce vDPA-based backend")
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> ---
>   drivers/vhost/vdpa.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index c50079dfb281..5500e3bf05c1 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -723,6 +723,7 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
>   	if (r)
>   		return r;
>   
> +	mutex_lock(&dev->mutex);

I think this should be done before the vhost_dev_check_owner() above.

Thanks

>   	switch (msg->type) {
>   	case VHOST_IOTLB_UPDATE:
>   		r = vhost_vdpa_process_iotlb_update(v, msg);
> @@ -742,6 +743,7 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
>   		r = -EINVAL;
>   		break;
>   	}
> +	mutex_unlock(&dev->mutex);
>   
>   	return r;
>   }