Re: [dpdk-dev] [PATCH v2 37/44] net/virtio: make server mode blocking

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Wednesday, January 20, 2021 5:25 AM
> To: dev@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>; olivier.matz@6wind.com;
> amorenoz@redhat.com; david.marchand@redhat.com
> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> Subject: [PATCH v2 37/44] net/virtio: make server mode blocking
> 
> This patch makes the Vhost-user backend server mode
> blocking at init, waiting for the client connection.
> 
> The goal is to make the driver more reliable, as without
> waiting for client connection, the Virtio driver has to
> assume the Vhost-user backend will support all the
> features it has advertized, which could lead to undefined
> behaviour.
> 
> For example, without this patch, if the user enables packed
> ring Virtio feature but the backend does not support it,
> the ring initialized by the driver will not be compatible
> with the backend.
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  drivers/net/virtio/virtio_user/vhost_user.c   |   9 +-
>  .../net/virtio/virtio_user/virtio_user_dev.c  | 121 +++++++-----------
>  drivers/net/virtio/virtio_user_ethdev.c       |   5 -
>  3 files changed, 55 insertions(+), 80 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_user/vhost_user.c
> b/drivers/net/virtio/virtio_user/vhost_user.c
> index fb6fcc82c9..a48fadd8c9 100644
> --- a/drivers/net/virtio/virtio_user/vhost_user.c
> +++ b/drivers/net/virtio/virtio_user/vhost_user.c
> @@ -692,6 +692,14 @@ virtio_user_start_server(struct virtio_user_dev *dev,
> struct sockaddr_un *un)
>  	if (ret < 0)
>  		return -1;
> 
> +	PMD_DRV_LOG(NOTICE, "(%s) waiting for client connection...", dev->path);
> +	dev->vhostfd = accept(fd, NULL, NULL);
> +	if (dev->vhostfd < 0) {
> +		PMD_DRV_LOG(ERR, "Failed to accept initial client connection (%s)",
> +				strerror(errno));
> +		return -1;
> +	}
> +
>  	flag = fcntl(fd, F_GETFL);
>  	if (fcntl(fd, F_SETFL, flag | O_NONBLOCK) < 0) {
>  		PMD_DRV_LOG(ERR, "fcntl failed, %s", strerror(errno));
> @@ -736,7 +744,6 @@ vhost_user_setup(struct virtio_user_dev *dev)
>  			close(fd);
>  			return -1;
>  		}
> -		dev->vhostfd = -1;
>  	} else {
>  		if (connect(fd, (struct sockaddr *)&un, sizeof(un)) < 0) {
>  			PMD_DRV_LOG(ERR, "connect error, %s", strerror(errno));
> diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c
> b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> index 95204ea955..c2a41fe3a0 100644
> --- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
> +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> @@ -144,10 +144,6 @@ virtio_user_dev_set_features(struct virtio_user_dev *dev)
> 
>  	pthread_mutex_lock(&dev->mutex);
> 
> -	if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER &&
> -			dev->vhostfd < 0)
> -		goto error;
> -
>  	/* Step 0: tell vhost to create queues */
>  	if (virtio_user_queue_setup(dev, virtio_user_create_queue) < 0)
>  		goto error;
> @@ -190,11 +186,6 @@ virtio_user_start_device(struct virtio_user_dev *dev)
>  	rte_mcfg_mem_read_lock();
>  	pthread_mutex_lock(&dev->mutex);
> 
> -	/* Vhost-user client not connected yet, will start later */
> -	if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER &&
> -			dev->vhostfd < 0)
> -		goto out;
> -
>  	/* Step 2: share memory regions */
>  	ret = dev->ops->set_memory_table(dev);
>  	if (ret < 0)
> @@ -213,7 +204,7 @@ virtio_user_start_device(struct virtio_user_dev *dev)
>  		goto error;
> 
>  	dev->started = true;
> -out:
> +
>  	pthread_mutex_unlock(&dev->mutex);
>  	rte_mcfg_mem_read_unlock();
> 
> @@ -422,36 +413,36 @@ virtio_user_dev_setup(struct virtio_user_dev *dev)
>  			PMD_DRV_LOG(ERR, "Server mode only supports vhost-user!");
>  			return -1;
>  		}
> +	}
> +
> +	if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER) {
>  		dev->ops = &virtio_ops_user;
> -	} else {
> -		if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER) {
> -			dev->ops = &virtio_ops_user;
> -		} else if (dev->backend_type ==
> -					VIRTIO_USER_BACKEND_VHOST_KERNEL) {
> -			dev->ops = &virtio_ops_kernel;
> -
> -			dev->vhostfds = malloc(dev->max_queue_pairs *
> -					       sizeof(int));
> -			dev->tapfds = malloc(dev->max_queue_pairs *
> -					     sizeof(int));
> -			if (!dev->vhostfds || !dev->tapfds) {
> -				PMD_INIT_LOG(ERR, "(%s) Failed to allocate FDs", dev-
> >path);
> -				return -1;
> -			}
> -
> -			for (q = 0; q < dev->max_queue_pairs; ++q) {
> -				dev->vhostfds[q] = -1;
> -				dev->tapfds[q] = -1;
> -			}
> -		} else if (dev->backend_type ==
> -				VIRTIO_USER_BACKEND_VHOST_VDPA) {
> -			dev->ops = &virtio_ops_vdpa;
> -		} else {
> -			PMD_DRV_LOG(ERR, "(%s) Unknown backend type", dev->path);
> +	} else if (dev->backend_type ==
> +			VIRTIO_USER_BACKEND_VHOST_KERNEL) {
> +		dev->ops = &virtio_ops_kernel;
> +
> +		dev->vhostfds = malloc(dev->max_queue_pairs *
> +				sizeof(int));
> +		dev->tapfds = malloc(dev->max_queue_pairs *
> +				sizeof(int));
> +		if (!dev->vhostfds || !dev->tapfds) {
> +			PMD_INIT_LOG(ERR, "(%s) Failed to allocate FDs", dev->path);
>  			return -1;
>  		}
> +
> +		for (q = 0; q < dev->max_queue_pairs; ++q) {
> +			dev->vhostfds[q] = -1;
> +			dev->tapfds[q] = -1;
> +		}
> +	} else if (dev->backend_type ==
> +			VIRTIO_USER_BACKEND_VHOST_VDPA) {
> +		dev->ops = &virtio_ops_vdpa;
> +	} else {
> +		PMD_DRV_LOG(ERR, "(%s) Unknown backend type", dev->path);
> +		return -1;
>  	}
> 
> +
>  	if (dev->ops->setup(dev) < 0) {
>  		PMD_INIT_LOG(ERR, "(%s) Failed to setup backend\n", dev->path);
>  		return -1;
> @@ -541,54 +532,36 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char
> *path, int queues,
>  		dev->unsupported_features |=
>  			(1ULL << VHOST_USER_F_PROTOCOL_FEATURES);
> 
> -	if (!dev->is_server) {
> -		if (dev->ops->set_owner(dev) < 0) {
> -			PMD_INIT_LOG(ERR, "(%s) Failed to set backend owner", dev-
> >path);
> -			return -1;
> -		}
> +	if (dev->ops->set_owner(dev) < 0) {
> +		PMD_INIT_LOG(ERR, "(%s) Failed to set backend owner", dev->path);
> +		return -1;
> +	}
> +
> +	if (dev->ops->get_features(dev, &dev->device_features) < 0) {
> +		PMD_INIT_LOG(ERR, "(%s) Failed to get backend features", dev-
> >path);
> +		return -1;
> +	}
> 
> -		if (dev->ops->get_features(dev, &dev->device_features) < 0) {
> -			PMD_INIT_LOG(ERR, "(%s) Failed to get backend features",
> dev->path);
> +	if ((dev->device_features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES)) ||
> +			dev->backend_type == VIRTIO_USER_BACKEND_VHOST_VDPA) {
> +		if (dev->ops->get_protocol_features(dev, &protocol_features)) {
> +			PMD_INIT_LOG(ERR, "(%s) Failed to get backend protocol
> features",
> +					dev->path);
>  			return -1;
>  		}
> 
> +		dev->protocol_features &= protocol_features;
> 
> -		if ((dev->device_features & (1ULL <<
> VHOST_USER_F_PROTOCOL_FEATURES)) ||
> -				(dev->backend_type == VIRTIO_USER_BACKEND_VHOST_VDPA))
> {
> -			if (dev->ops->get_protocol_features(dev, &protocol_features))
> {
> -				PMD_INIT_LOG(ERR, "(%s) Failed to get backend protocol
> features",
> -						dev->path);
> -				return -1;
> -			}
> -
> -			dev->protocol_features &= protocol_features;
> -
> -			if (dev->ops->set_protocol_features(dev, dev-
> >protocol_features)) {
> -				PMD_INIT_LOG(ERR, "(%s) Failed to set backend protocol
> features",
> -						dev->path);
> -				return -1;
> -			}
> -
> -			if (!(dev->protocol_features & (1ULL <<
> VHOST_USER_PROTOCOL_F_MQ)))
> -				dev->unsupported_features |= (1ull << VIRTIO_NET_F_MQ);
> +		if (dev->ops->set_protocol_features(dev, dev->protocol_features))
> {
> +			PMD_INIT_LOG(ERR, "(%s) Failed to set backend protocol
> features",
> +					dev->path);
> +			return -1;
>  		}
> -	} else {
> -		/* We just pretend vhost-user can support all these features.
> -		 * Note that this could be problematic that if some feature is
> -		 * negotiated but not supported by the vhost-user which comes
> -		 * later.
> -		 */
> -		dev->device_features = VIRTIO_USER_SUPPORTED_FEATURES;
> 
> -		/* We cannot assume VHOST_USER_PROTOCOL_F_STATUS is supported
> -		 * until it's negotiated
> -		 */
> -		dev->protocol_features &=
> -			~(1ULL << VHOST_USER_PROTOCOL_F_STATUS);
> +		if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ)))
> +			dev->unsupported_features |= (1ull << VIRTIO_NET_F_MQ);
>  	}
> 
> -
> -
>  	if (!mrg_rxbuf)
>  		dev->unsupported_features |= (1ull << VIRTIO_NET_F_MRG_RXBUF);
> 
> diff --git a/drivers/net/virtio/virtio_user_ethdev.c
> b/drivers/net/virtio/virtio_user_ethdev.c
> index 5e256f4e6d..e822d93690 100644
> --- a/drivers/net/virtio/virtio_user_ethdev.c
> +++ b/drivers/net/virtio/virtio_user_ethdev.c
> @@ -174,11 +174,6 @@ virtio_user_delayed_handler(void *param)
>  		if (dev->vhostfd >= 0) {
>  			close(dev->vhostfd);
>  			dev->vhostfd = -1;
> -			/* Until the featuers are negotiated again, don't assume
> -			 * the backend supports VHOST_USER_PROTOCOL_F_STATUS
> -			 */
> -			dev->protocol_features &=
> -				~(1ULL << VHOST_USER_PROTOCOL_F_STATUS);
>  		}
>  		eth_dev->intr_handle->fd = dev->listenfd;
>  		rte_intr_callback_register(eth_dev->intr_handle,
> --
> 2.29.2

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>