Re: [PATCH v6] net/virtio-user: add support for server mode

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

On 4/6/2018 8:18 AM, zhiyong.yang@intel.com wrote:
> In a container environment if the vhost-user backend restarts, there's
> no way for it to reconnect to virtio-user. To address this, support for
> server mode is added. In this mode the socket file is created by virtio-
> user, which the backend then connects to. This means that if the backend
> restarts, it can reconnect to virtio-user and continue communications.
>
> With current implementation, LSC is enabled at virtio-user side to
> support to accept the coming connection.
>
> Release note is updated in this patch.
>
> Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> ---
>
> Changes in V6:
> 1. fix report wrong link stauts in server mode.
> 2. fix some code style issues.
>
> Changes in V5:
> 1. Support server mode virtio-user startup in non-blocking mode.
> 2. rebase on top of dpdk-next-virtio.
>
> Changes in V4:
> 1. Don't create new pthread any more and use librte_eal interrupt thread.
> 2. virtio-user doesn't work in blocking mode any more for the first connection.
> Client mode vhost-user startups firstly, then server mode virtio-user creates
> socket file and startups. Keep consistency with usage of client mode
> virtio-user.
>
> Changes in V3:
> 1. use EAL epoll mechanism instead of vhost events. Cancel to export vhost
> event APIs.
> 2. rebase the code on top of dpdk-next-virtio
>
> Changes in V2:
> 1. split two patches 1/5 and 2/5 from v1 patchset to fix some existing issues
> which is not strongly related to support for server mode
> 2. move fdset related functions to librte_eal from librte_vhost exposed as
> new APIs.
> 3. release note is added in the patch 5/5.
> 4. squash data structure change patch into 4/5 according to Maxime's suggestion.
>
>   doc/guides/rel_notes/release_18_05.rst           |   6 ++
>   drivers/net/virtio/virtio_user/vhost_user.c      |  45 ++++++++--
>   drivers/net/virtio/virtio_user/virtio_user_dev.c |  40 +++++++--
>   drivers/net/virtio/virtio_user/virtio_user_dev.h |   3 +
>   drivers/net/virtio/virtio_user_ethdev.c          | 101 ++++++++++++++++++++---
>   5 files changed, 171 insertions(+), 24 deletions(-)
>
> diff --git a/doc/guides/rel_notes/release_18_05.rst b/doc/guides/rel_notes/release_18_05.rst
> index 9cc77f893..f8897b2e9 100644
> --- a/doc/guides/rel_notes/release_18_05.rst
> +++ b/doc/guides/rel_notes/release_18_05.rst
> @@ -58,6 +58,12 @@ New Features
>     * Added support for NVGRE, VXLAN and GENEVE filters in flow API.
>     * Added support for DROP action in flow API.
>   
> +* **Added support for virtio-user server mode.**
> +  In a container environment if the vhost-user backend restarts, there's no way
> +  for it to reconnect to virtio-user. To address this, support for server mode
> +  is added. In this mode the socket file is created by virtio-user, which the
> +  backend connects to. This means that if the backend restarts, it can reconnect
> +  to virtio-user and continue communications.
>   
>   API Changes
>   -----------
> diff --git a/drivers/net/virtio/virtio_user/vhost_user.c b/drivers/net/virtio/virtio_user/vhost_user.c
> index 91c6449bb..a6df97a00 100644
> --- a/drivers/net/virtio/virtio_user/vhost_user.c
> +++ b/drivers/net/virtio/virtio_user/vhost_user.c
> @@ -378,6 +378,30 @@ vhost_user_sock(struct virtio_user_dev *dev,
>   	return 0;
>   }
>   
> +#define MAX_VIRTIO_USER_BACKLOG 1
> +static int
> +virtio_user_start_server(struct virtio_user_dev *dev, struct sockaddr_un *un)
> +{
> +	int ret;
> +	int flag;
> +	int fd = dev->listenfd;
> +
> +	ret = bind(fd, (struct sockaddr *)un, sizeof(*un));
> +	if (ret < 0) {
> +		PMD_DRV_LOG(ERR, "failed to bind to %s: %s; remove it and try again\n",
> +			    dev->path, strerror(errno));
> +		return -1;
> +	}
> +	ret = listen(fd, MAX_VIRTIO_USER_BACKLOG);
> +	if (ret < 0)
> +		return -1;
> +
> +	flag = fcntl(fd, F_GETFL);
> +	fcntl(fd, F_SETFL, flag | O_NONBLOCK);
> +
> +	return 0;
> +}
> +
>   /**
>    * Set up environment to talk with a vhost user backend.
>    *
> @@ -405,13 +429,24 @@ vhost_user_setup(struct virtio_user_dev *dev)
>   	memset(&un, 0, sizeof(un));
>   	un.sun_family = AF_UNIX;
>   	snprintf(un.sun_path, sizeof(un.sun_path), "%s", dev->path);
> -	if (connect(fd, (struct sockaddr *)&un, sizeof(un)) < 0) {
> -		PMD_DRV_LOG(ERR, "connect error, %s", strerror(errno));
> -		close(fd);
> -		return -1;
> +
> +	if (dev->is_server) {
> +		dev->listenfd = fd;
> +		if (virtio_user_start_server(dev, &un) < 0) {
> +			PMD_DRV_LOG(ERR, "virtio-user startup fails in server mode");
> +			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));
> +			close(fd);
> +			return -1;
> +		}
> +		dev->vhostfd = fd;
>   	}
>   
> -	dev->vhostfd = fd;
>   	return 0;
>   }
>   
> diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> index f90fee9e5..3b776282c 100644
> --- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
> +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> @@ -99,6 +99,9 @@ virtio_user_start_device(struct virtio_user_dev *dev)
>   	uint64_t features;
>   	int ret;
>   
> +	if (dev->vhostfd < 0)
> +		return -1;

This breaks virtio-user with vhost-kernel which does not need vhostfd, 
and will be always -1.

> +
>   	/* Do not check return as already done in init, or reset in stop */
>   	dev->ops->send_request(dev, VHOST_USER_SET_OWNER, NULL);
>   
> @@ -254,6 +257,8 @@ virtio_user_fill_intr_handle(struct virtio_user_dev *dev)
>   	eth_dev->intr_handle->fd = -1;
>   	if (dev->vhostfd >= 0)
>   		eth_dev->intr_handle->fd = dev->vhostfd;
> +	else if (dev->is_server)
> +		eth_dev->intr_handle->fd = dev->listenfd;
>   
>   	return 0;
>   }
> @@ -267,7 +272,7 @@ virtio_user_dev_setup(struct virtio_user_dev *dev)
>   	dev->vhostfds = NULL;
>   	dev->tapfds = NULL;
>   
> -	if (is_vhost_user_by_type(dev->path)) {
> +	if (dev->is_server || is_vhost_user_by_type(dev->path)) {

I think we still fail to pick out an invalidated case: specify "server" 
parameter for a vhost-kernel path.

>   		dev->ops = &ops_user;
>   	} else {
>   		dev->ops = &ops_kernel;
> @@ -337,16 +342,25 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
>   		return -1;
>   	}
>   
> -	if (dev->ops->send_request(dev, VHOST_USER_SET_OWNER, NULL) < 0) {
> -		PMD_INIT_LOG(ERR, "set_owner fails: %s", strerror(errno));
> -		return -1;
> -	}
> +	if (dev->vhostfd >= 0) {
> +		if (dev->ops->send_request(dev, VHOST_USER_SET_OWNER,
> +					   NULL) < 0) {
> +			PMD_INIT_LOG(ERR, "set_owner fails: %s",
> +				     strerror(errno));
> +			return -1;
> +		}
>   
> -	if (dev->ops->send_request(dev, VHOST_USER_GET_FEATURES,
> -			    &dev->device_features) < 0) {
> -		PMD_INIT_LOG(ERR, "get_features failed: %s", strerror(errno));
> -		return -1;
> +		if (dev->ops->send_request(dev, VHOST_USER_GET_FEATURES,
> +					   &dev->device_features) < 0) {
> +			PMD_INIT_LOG(ERR, "get_features failed: %s",
> +				     strerror(errno));
> +			return -1;
> +		}
> +	} else {
> +		/* Just pretend vhost-user can support all these features */

Although I don't think we need to fix this, please also 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;
>   	}
> +
>   	if (dev->mac_specified)
>   		dev->device_features |= (1ull << VIRTIO_NET_F_MAC);
>   
> @@ -388,6 +402,11 @@ virtio_user_dev_uninit(struct virtio_user_dev *dev)
>   
>   	close(dev->vhostfd);
>   
> +	if (dev->is_server && dev->listenfd >= 0) {
> +		close(dev->listenfd);
> +		dev->listenfd = -1;
> +	}
> +
>   	if (dev->vhostfds) {
>   		for (i = 0; i < dev->max_queue_pairs; ++i)
>   			close(dev->vhostfds[i]);
> @@ -396,6 +415,9 @@ virtio_user_dev_uninit(struct virtio_user_dev *dev)
>   	}
>   
>   	free(dev->ifname);
> +
> +	if (dev->is_server)
> +		unlink(dev->path);
>   }
>   
>   static uint8_t
> diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.h b/drivers/net/virtio/virtio_user/virtio_user_dev.h
> index 5f8755771..ade727e46 100644
> --- a/drivers/net/virtio/virtio_user/virtio_user_dev.h
> +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.h
> @@ -6,6 +6,7 @@
>   #define _VIRTIO_USER_DEV_H
>   
>   #include <limits.h>
> +#include <stdbool.h>
>   #include "../virtio_pci.h"
>   #include "../virtio_ring.h"
>   #include "vhost.h"
> @@ -13,6 +14,8 @@
>   struct virtio_user_dev {
>   	/* for vhost_user backend */
>   	int		vhostfd;
> +	int		listenfd;   /* listening fd */
> +	bool		is_server;  /* server or client mode */
>   
>   	/* for vhost_kernel backend */
>   	char		*ifname;
> diff --git a/drivers/net/virtio/virtio_user_ethdev.c b/drivers/net/virtio/virtio_user_ethdev.c
> index 263649006..4e7b3c34f 100644
> --- a/drivers/net/virtio/virtio_user_ethdev.c
> +++ b/drivers/net/virtio/virtio_user_ethdev.c
> @@ -24,15 +24,73 @@
>   #define virtio_user_get_dev(hw) \
>   	((struct virtio_user_dev *)(hw)->virtio_user_dev)
>   
> +static int
> +virtio_user_server_reconnect(struct virtio_user_dev *dev)
> +{
> +	int ret;
> +	int flag;
> +	int connectfd;
> +	struct rte_eth_dev *eth_dev = &rte_eth_devices[dev->port_id];
> +
> +	connectfd = accept(dev->listenfd, NULL, NULL);
> +	if (connectfd < 0)
> +		return -1;
> +
> +	dev->vhostfd = connectfd;
> +	flag = fcntl(connectfd, F_GETFD);
> +	fcntl(connectfd, F_SETFL, flag | O_NONBLOCK);
> +
> +	ret = virtio_user_start_device(dev);
> +	if (ret < 0)
> +		return -1;
> +
> +	if (eth_dev->data->dev_flags & RTE_ETH_DEV_INTR_LSC) {
> +		if (rte_intr_disable(eth_dev->intr_handle) < 0) {
> +			PMD_DRV_LOG(ERR, "interrupt disable failed");
> +			return -1;
> +		}
> +		rte_intr_callback_unregister(eth_dev->intr_handle,
> +					     virtio_interrupt_handler,
> +					     eth_dev);
> +		eth_dev->intr_handle->fd = connectfd;
> +		rte_intr_callback_register(eth_dev->intr_handle,
> +					   virtio_interrupt_handler, eth_dev);
> +
> +		if (rte_intr_enable(eth_dev->intr_handle) < 0) {
> +			PMD_DRV_LOG(ERR, "interrupt enable failed");
> +			return -1;
> +		}
> +	}
> +	PMD_INIT_LOG(NOTICE, "server mode virtio-user reconnection succeeds!");
> +	return 0;
> +}
> +
>   static void
>   virtio_user_delayed_handler(void *param)
>   {
>   	struct virtio_hw *hw = (struct virtio_hw *)param;
> -	struct rte_eth_dev *dev = &rte_eth_devices[hw->port_id];
> +	struct rte_eth_dev *eth_dev = &rte_eth_devices[hw->port_id];
> +	struct virtio_user_dev *dev = virtio_user_get_dev(hw);
>   
> -	rte_intr_callback_unregister(dev->intr_handle,
> -				     virtio_interrupt_handler,
> -				     dev);
> +	if (rte_intr_disable(eth_dev->intr_handle) < 0) {
> +		PMD_DRV_LOG(ERR, "interrupt disable failed");
> +		return;
> +	}
> +	rte_intr_callback_unregister(eth_dev->intr_handle,
> +				     virtio_interrupt_handler, eth_dev);
> +	if (dev->is_server) {
> +		if (dev->vhostfd >= 0) {
> +			close(dev->vhostfd);
> +			dev->vhostfd = -1;
> +		}
> +		eth_dev->intr_handle->fd = dev->listenfd;
> +		rte_intr_callback_register(eth_dev->intr_handle,
> +					   virtio_interrupt_handler, eth_dev);
> +		if (rte_intr_enable(eth_dev->intr_handle) < 0) {
> +			PMD_DRV_LOG(ERR, "interrupt enable failed");
> +			return;
> +		}
> +	}
>   }
>   
>   static void
> @@ -67,12 +125,10 @@ virtio_user_read_dev_config(struct virtio_hw *hw, size_t offset,
>   				dev->status &= (~VIRTIO_NET_S_LINK_UP);
>   				PMD_DRV_LOG(ERR, "virtio-user port %u is down",
>   					    hw->port_id);
> -				/* Only client mode is available now. Once the
> -				 * connection is broken, it can never be up
> -				 * again. Besides, this function could be called
> -				 * in the process of interrupt handling,
> -				 * callback cannot be unregistered here, set an
> -				 * alarm to do it.
> +
> +				/* This function could be called in the process
> +				 * of interrupt handling, callback cannot be
> +				 * unregistered here, set an alarm to do it.
>   				 */
>   				rte_eal_alarm_set(1,
>   						  virtio_user_delayed_handler,
> @@ -85,7 +141,12 @@ virtio_user_read_dev_config(struct virtio_hw *hw, size_t offset,
>   				PMD_DRV_LOG(ERR, "error clearing O_NONBLOCK flag");
>   				return;
>   			}
> +		} else if (dev->is_server) {
> +			dev->status &= (~VIRTIO_NET_S_LINK_UP);
> +			if (virtio_user_server_reconnect(dev) >= 0)
> +				dev->status |= VIRTIO_NET_S_LINK_UP;
>   		}
> +
>   		*(uint16_t *)dst = dev->status;
>   	}
>   
> @@ -278,12 +339,15 @@ static const char *valid_args[] = {
>   	VIRTIO_USER_ARG_QUEUE_SIZE,
>   #define VIRTIO_USER_ARG_INTERFACE_NAME "iface"
>   	VIRTIO_USER_ARG_INTERFACE_NAME,
> +#define VIRTIO_USER_ARG_SERVER_MODE "server"
> +	VIRTIO_USER_ARG_SERVER_MODE,
>   	NULL
>   };
>   
>   #define VIRTIO_USER_DEF_CQ_EN	0
>   #define VIRTIO_USER_DEF_Q_NUM	1
>   #define VIRTIO_USER_DEF_Q_SZ	256
> +#define VIRTIO_USER_DEF_SERVER_MODE	0
>   
>   static int
>   get_string_arg(const char *key __rte_unused,
> @@ -378,6 +442,7 @@ virtio_user_pmd_probe(struct rte_vdev_device *dev)
>   	uint64_t queues = VIRTIO_USER_DEF_Q_NUM;
>   	uint64_t cq = VIRTIO_USER_DEF_CQ_EN;
>   	uint64_t queue_size = VIRTIO_USER_DEF_Q_SZ;
> +	uint64_t server_mode = VIRTIO_USER_DEF_SERVER_MODE;
>   	char *path = NULL;
>   	char *ifname = NULL;
>   	char *mac_addr = NULL;
> @@ -445,6 +510,15 @@ virtio_user_pmd_probe(struct rte_vdev_device *dev)
>   		}
>   	}
>   
> +	if (rte_kvargs_count(kvlist, VIRTIO_USER_ARG_SERVER_MODE) == 1) {
> +		if (rte_kvargs_process(kvlist, VIRTIO_USER_ARG_SERVER_MODE,
> +				       &get_integer_arg, &server_mode) < 0) {
> +			PMD_INIT_LOG(ERR, "error to parse %s",
> +				     VIRTIO_USER_ARG_SERVER_MODE);
> +			goto end;
> +		}
> +	}
> +
>   	if (rte_kvargs_count(kvlist, VIRTIO_USER_ARG_CQ_NUM) == 1) {
>   		if (rte_kvargs_process(kvlist, VIRTIO_USER_ARG_CQ_NUM,
>   				       &get_integer_arg, &cq) < 0) {
> @@ -469,6 +543,8 @@ virtio_user_pmd_probe(struct rte_vdev_device *dev)
>   	}
>   
>   	if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
> +		struct virtio_user_dev *vu_dev;
> +
>   		eth_dev = virtio_user_eth_dev_alloc(dev);
>   		if (!eth_dev) {
>   			PMD_INIT_LOG(ERR, "virtio_user fails to alloc device");
> @@ -476,6 +552,11 @@ virtio_user_pmd_probe(struct rte_vdev_device *dev)
>   		}
>   
>   		hw = eth_dev->data->dev_private;
> +		vu_dev = virtio_user_get_dev(hw);
> +		if (server_mode == 1)
> +			vu_dev->is_server = true;
> +		else
> +			vu_dev->is_server = false;
>   		if (virtio_user_dev_init(hw->virtio_user_dev, path, queues, cq,
>   				 queue_size, mac_addr, &ifname) < 0) {
>   			PMD_INIT_LOG(ERR, "virtio_user_dev_init fails");