Re: [dpdk-dev] [PATCH] net/virtio-user: fix feature setting with vhost-net backend

[Jiayu Hu <jiayu.hu@intel.com>]

Hi Tiwei,

On Tue, May 08, 2018 at 10:49:50AM +0800, Tiwei Bie wrote:
> On Mon, May 07, 2018 at 02:50:06PM +0800, Jiayu Hu wrote:
> > Currently, when the backend is vhost-net, which implies
> > virtio-user works in client mode, virtio-user is assigned
> > to the default feature VIRTIO_USER_SUPPORTED_FEATURES.
> > However, virtio-user should request features from the
> > backend in this case.
> > 
> > Fixes: bd8f50a45d0f ("net/virtio-user: support server mode")
> > Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> > ---
> >  drivers/net/virtio/virtio_user/virtio_user_dev.c | 15 +++++++--------
> >  1 file changed, 7 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> > index 38b8bc9..f745163 100644
> > --- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
> > +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> > @@ -353,20 +353,22 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
> >  		return -1;
> >  	}
> >  
> > -	if (dev->vhostfd >= 0) {
> > +	if (!dev->is_server) {
> 
> Server mode also needs to run below code when the
> connection to the backend is established.

For server mode, the below code is called by virtio_user_start_device(),
instead of virtio_user_dev_init(). Only client mode virtio-user
needs to call it when init.

> 
> >  		if (dev->ops->send_request(dev, VHOST_USER_SET_OWNER,
> > -					   NULL) < 0) {
> > +					NULL) < 0) {
> 
> There is no need to change the indent.

Thanks, change in the next patch.

> 
> >  			PMD_INIT_LOG(ERR, "set_owner fails: %s",
> > -				     strerror(errno));
> > +					strerror(errno));
> 
> There is no need to change the indent.

ditto.

> 
> >  			return -1;
> >  		}
> >  
> >  		if (dev->ops->send_request(dev, VHOST_USER_GET_FEATURES,
> > -					   &dev->device_features) < 0) {
> > +					&dev->device_features) < 0) {
> 
> There is no need to change the indent.

ditto.

> 
> >  			PMD_INIT_LOG(ERR, "get_features failed: %s",
> > -				     strerror(errno));
> > +					strerror(errno));
> 
> There is no need to change the indent.

ditto.

> 
> >  			return -1;
> >  		}
> > +		if (dev->mac_specified)
> > +			dev->device_features |= (1ull << VIRTIO_NET_F_MAC);
> 
> Why move above code?

The server mode virtio-user is assigned the default features, which include
VIRTIO_NET_F_MAC. So checking if support VIRTIO_NET_F_MAC is only necessary
for client mode.

Thanks,
Jiayu

> 
> >  	} else {
> >  		/* We just pretend vhost-user can support all these features.
> >  		 * Note that this could be problematic that if some feature is
> > @@ -376,9 +378,6 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
> >  		dev->device_features = VIRTIO_USER_SUPPORTED_FEATURES;
> >  	}
> >  
> > -	if (dev->mac_specified)
> > -		dev->device_features |= (1ull << VIRTIO_NET_F_MAC);
> > -
> >  	if (cq) {
> >  		/* device does not really need to know anything about CQ,
> >  		 * so if necessary, we just claim to support CQ
> > -- 
> > 2.7.4
> >