Re: [PATCH v4 1/1] net/virtio-user: add support for server mode

["Yang, Zhiyong" <zhiyong.yang@intel.com>]

Hi Jiafeng,

Thanks for your review and comments firstly.
Reply inline.

> -----Original Message-----
> From: Tan, Jianfeng
> Sent: Tuesday, April 3, 2018 11:16 PM
> To: Yang, Zhiyong <zhiyong.yang@intel.com>; dev@dpdk.org
> Cc: maxime.coquelin@redhat.com; thomas@monjalon.net; Wang, Zhihong
> <zhihong.wang@intel.com>; Bie, Tiwei <tiwei.bie@intel.com>
> Subject: Re: [PATCH v4 1/1] net/virtio-user: add support for server mode
> 
> 
> 
> On 4/3/2018 8:20 PM, zhiyong.yang@intel.com wrote:
> > virtio-user adds support for server mode in this patch.
> >
> > Client mode vhost-user startup firstly, server mode virtio-user
> > startups and creates the socket file to exchange vhost messages.
> >
> > If the connection is broken, client mode vhost-user can support to
> > reconnect virtio-user.
> >
> > Server mode virtio-user supports many times' vhost-user reconnections
> > with the same parameter configurations.
> >
> > Release note is updated in the patch.
> 
> With current implementation, we have to enable LSC; or no chance to accept
> the coming connection. We shall point this out.
> 
Ok.

> And if possible, split this patch into multiple patches.
>
How to split?

> >
> > Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> > ---
> >   doc/guides/rel_notes/release_18_05.rst           |   6 ++
> >   drivers/net/virtio/virtio_user/vhost_user.c      |  64 ++++++++++++--
> >   drivers/net/virtio/virtio_user/virtio_user_dev.c |  45 +++++++---
> >   drivers/net/virtio/virtio_user/virtio_user_dev.h |   4 +
> >   drivers/net/virtio/virtio_user_ethdev.c          | 103
> +++++++++++++++++++++--
> >   5 files changed, 194 insertions(+), 28 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..1b3401d4f 100644
> > --- a/drivers/net/virtio/virtio_user/vhost_user.c
> > +++ b/drivers/net/virtio/virtio_user/vhost_user.c
> > @@ -378,6 +378,50 @@ vhost_user_sock(struct virtio_user_dev *dev,
> >   	return 0;
> >   }
> >
> > +static void
> > +virtio_user_set_block(int fd, bool enabled)
> 
> This is only used once, no need to abstract it into a function?

Ok.

> 
> > +{
> > +	int f;
> > +
> > +	f = fcntl(fd, F_GETFL);
> > +	if (enabled)
> > +		fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
> > +	else
> > +		fcntl(fd, F_SETFL, f | O_NONBLOCK); }
> > +
> > +#define MAX_VIRTIO_USER_BACKLOG 128
> 
> We only allow one connection from vhost-user, so how about just make the
> backlog queue length as 1?
> 
> > +static int
> > +virtio_user_start_server(struct virtio_user_dev *dev, struct
> > +sockaddr_un *un) {
> > +	int ret;
> > +	int fd = dev->listenfd;
> > +	int connectfd;
> > +
> > +	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));
> > +		goto err;
> > +	}
> > +	ret = listen(fd, MAX_VIRTIO_USER_BACKLOG);
> > +	if (ret < 0)
> > +		goto err;
> > +
> > +	connectfd = accept(fd, NULL, NULL);
> > +	if (connectfd >= 0)
> > +		dev->connected = true;
> > +	else
> > +		goto err;
> 
> if (connectfd < 0)
>          goto err;
> 
> dev->connected = true;
> dev->vhostfd = connectfd;
> ...

Ok.

> 
> > +
> > +	dev->vhostfd = connectfd;
> > +	virtio_user_set_block(connectfd, true);
> > +	return 0;
> > +err:
> > +	close(dev->listenfd);
> > +	return -1;
> > +}
> > +
> >   /**
> >    * Set up environment to talk with a vhost user backend.
> >    *
> > @@ -390,6 +434,7 @@ vhost_user_setup(struct virtio_user_dev *dev)
> >   {
> >   	int fd;
> >   	int flag;
> > +	int ret = 0;
> >   	struct sockaddr_un un;
> >
> >   	fd = socket(AF_UNIX, SOCK_STREAM, 0); @@ -405,14 +450,21 @@
> > 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;
> > +		ret = virtio_user_start_server(dev, &un);
> > +	} else {
> > +		dev->vhostfd = fd;
> > +		if (connect(fd, (struct sockaddr *)&un, sizeof(un)) < 0) {
> > +			PMD_DRV_LOG(ERR, "connect error, %s",
> strerror(errno));
> > +			close(fd);
> > +			return -1;
> > +		}
> > +		dev->connected = true;
> >   	}
> >
> > -	dev->vhostfd = fd;
> > -	return 0;
> > +	return ret;
> >   }
> >
> >   static int
> > diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c
> > b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> > index f90fee9e5..dd9fa9bdf 100644
> > --- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
> > +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> > @@ -142,6 +142,9 @@ int virtio_user_stop_device(struct virtio_user_dev
> *dev)
> >   {
> >   	uint32_t i;
> >
> > +	if (!dev->connected)
> > +		return -1;
> > +
> >   	for (i = 0; i < dev->max_queue_pairs; ++i)
> >   		dev->ops->enable_qp(dev, i, 0);
> >
> > @@ -267,21 +270,27 @@ virtio_user_dev_setup(struct virtio_user_dev
> *dev)
> >   	dev->vhostfds = NULL;
> >   	dev->tapfds = NULL;
> 
> Add a check here:
> if (dev->is_server && !is_vhost_user_by_type(dev->path))
>          return error;

Ok.

> 
> >
> > -	if (is_vhost_user_by_type(dev->path)) {
> > -		dev->ops = &ops_user;
> > +	if (dev->is_server) {
> > +		dev->ops = &ops_user;/* server mode only supports vhost
> user*/
> >   	} else {
> > -		dev->ops = &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, "Failed to malloc");
> > -			return -1;
> > -		}
> > -
> > -		for (q = 0; q < dev->max_queue_pairs; ++q) {
> > -			dev->vhostfds[q] = -1;
> > -			dev->tapfds[q] = -1;
> > +		if (is_vhost_user_by_type(dev->path)) {
> > +			dev->ops = &ops_user;
> > +		} else {
> > +			dev->ops = &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, "Failed to malloc");
> > +				return -1;
> > +			}
> > +
> > +			for (q = 0; q < dev->max_queue_pairs; ++q) {
> > +				dev->vhostfds[q] = -1;
> > +				dev->tapfds[q] = -1;
> > +			}
> >   		}
> >   	}
> >
> > @@ -388,6 +397,11 @@ 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;
> > +	}
> > +	dev->connected = false;
> >   	if (dev->vhostfds) {
> >   		for (i = 0; i < dev->max_queue_pairs; ++i)
> >   			close(dev->vhostfds[i]);
> > @@ -396,6 +410,9 @@ 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 64467b4f9..68056720d 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 +14,9 @@
> >   struct virtio_user_dev {
> >   	/* for vhost_user backend */
> >   	int		vhostfd;
> > +	int		listenfd;   /* listening fd */
> > +	bool		connected;  /* connection status */
> 
> Seems not necessary to add this field; as the connection status can be
> deduced from (vhostfd>=0)

Ok, remove it.

> 
> > +	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..5b8c8e291 100644
> > --- a/drivers/net/virtio/virtio_user_ethdev.c
> > +++ b/drivers/net/virtio/virtio_user_ethdev.c
> > @@ -24,15 +24,76 @@
> >   #define virtio_user_get_dev(hw) \
> >   	((struct virtio_user_dev *)(hw)->virtio_user_dev)
> >
> > +static void
> > +virtio_user_server_reconnection(struct virtio_user_dev *dev)
> 
> s/reconnection/reconnect?
>

Ok, Good Suggestion.
 
> > +{
> > +	int ret;
> > +	int flag;
> > +	int connectfd;
> > +	struct rte_eth_dev *eth_dev = &rte_eth_devices[dev->port_id];
> > +
> > +	if (dev->connected)
> > +		return;
> > +
> > +	connectfd = accept(dev->listenfd, NULL, NULL);
> > +	if (connectfd < 0)
> > +		return;
> > +
> > +	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;
> > +
> > +	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;
> > +		}
> > +		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;
> > +		}
> > +	}
> > +	dev->connected = true;
> > +	PMD_INIT_LOG(NOTICE, "server mode virtio-user reconnection
> > +succeeds!"); }
> > +
> >   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
> > @@ -65,8 +126,7 @@ virtio_user_read_dev_config(struct virtio_hw *hw,
> size_t offset,
> >   			r = recv(dev->vhostfd, buf, 128, MSG_PEEK);
> 
> As server mode and the connection is not connected, vhostfd is -1 now, then
> r < 0 and errno is EBADF, how could it go into server handling in the "else if"
> block?
> 

I think I don't catch you.  When server mode, if vhostfd = -1,
if (dev->vhostfd >= 0)  is false, so, the code will goto to check else if (dev->is_server)
to handle server mode.

> >   			if (r == 0 || (r < 0 && errno != EAGAIN)) {
> >   				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
> 
> Can you also correct this note as we support server mode now?

Ok.
> 
> >   				 * connection is broken, it can never be up
> >   				 * again. Besides, this function could be called
> @@ -74,9
> > +134,14 @@ virtio_user_read_dev_config(struct virtio_hw *hw, size_t
> offset,
> >   				 * callback cannot be unregistered here, set
> an
> >   				 * alarm to do it.
> >   				 */
> > -				rte_eal_alarm_set(1,
> > +				if (dev->connected) {
> > +					dev->connected = false;
> > +					PMD_DRV_LOG(ERR, "virtio-user
> port %u is down",
> > +						    hw->port_id);
> > +					rte_eal_alarm_set(1,
> >
> virtio_user_delayed_handler,
> >   						  (void *)hw);
> > +				}
> >   			} else {
> >   				dev->status |= VIRTIO_NET_S_LINK_UP;
> >   			}
> > @@ -85,7 +150,10 @@ 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)
> > +			virtio_user_server_reconnection(dev);
> > +
> >   		*(uint16_t *)dst = dev->status;
> >   	}
> >
> > @@ -278,12 +346,15 @@ 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, @@ -378,10 +449,12 @@
> > 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;
> >   	int ret = -1;
> > +	struct virtio_user_dev *vu_dev = NULL;
> >
> >   	kvlist = rte_kvargs_parse(rte_vdev_device_args(dev), valid_args);
> >   	if (!kvlist) {
> > @@ -445,6 +518,15 @@ 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) { @@ -476,6
> +558,11 @@
> > 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");