[DPDK,v1] examples/vhost: add vhostpmd support

  Added vHostPMD based configuration of vHost devices.
Currently vHost library calls are used for configuring the
vhost device.

vHostPMD is a pre-requisite for enabling future features
supported such as FPGA and possibly CBDMA. With the
vHostPMD integration, upstream features in PMD can be easily
supported and additional features such as queue stats for
vhost devices can be useful.

With the patch, user has an option to select
vHost PMD by passing "--use-vhost-pmd" option.
Disabled by default.

Note: vHost multi-queue is not enabled on this patch.

Signed-off-by: Sivaprasad Tummala <Sivaprasad.Tummala@intel.com>
---
 doc/guides/sample_app_ug/vhost.rst |   4 +
 examples/vhost/Makefile            |   4 +
 examples/vhost/main.c              | 475 ++++++++++++++++++++++++-----
 examples/vhost/main.h              |   1 +
 examples/vhost/meson.build         |   3 +-
 5 files changed, 402 insertions(+), 85 deletions(-)
  

Hi, Tummala

A few comments inline.

On 03/11, Sivaprasad Tummala wrote:
>Added vHostPMD based configuration of vHost devices.
>Currently vHost library calls are used for configuring the
>vhost device.
>
>vHostPMD is a pre-requisite for enabling future features
>supported such as FPGA and possibly CBDMA. With the
>vHostPMD integration, upstream features in PMD can be easily
>supported and additional features such as queue stats for
>vhost devices can be useful.
>
>With the patch, user has an option to select
>vHost PMD by passing "--use-vhost-pmd" option.
>Disabled by default.
>
>Note: vHost multi-queue is not enabled on this patch.
>
>Signed-off-by: Sivaprasad Tummala <Sivaprasad.Tummala@intel.com>
>---
> doc/guides/sample_app_ug/vhost.rst |   4 +
> examples/vhost/Makefile            |   4 +
> examples/vhost/main.c              | 475 ++++++++++++++++++++++++-----
> examples/vhost/main.h              |   1 +
> examples/vhost/meson.build         |   3 +-
> 5 files changed, 402 insertions(+), 85 deletions(-)
>
>diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst
>index a71ada654..bb6275249 100644
>--- a/doc/guides/sample_app_ug/vhost.rst
>+++ b/doc/guides/sample_app_ug/vhost.rst
>@@ -152,6 +152,10 @@ note that if NIC is bound to driver with iommu enabled, dequeue zero copy
> cannot work at VM2NIC mode (vm2vm=0) due to currently we don't setup iommu
> dma mapping for guest memory.
> 
>+**--use-vhost-pmd**
>+vHost DPDK PMD will be enabled when this option is given. By default, vHost
>+direct library calls are used to configure devices.
>+
> **--vlan-strip 0|1**
> VLAN strip option is removed, because different NICs have different behaviors
> when disabling VLAN strip. Such feature, which heavily depends on hardware,
>diff --git a/examples/vhost/Makefile b/examples/vhost/Makefile
>index f2b161541..727cbe9d3 100644
>--- a/examples/vhost/Makefile
>+++ b/examples/vhost/Makefile
>@@ -63,6 +63,10 @@ CFLAGS += -DALLOW_EXPERIMENTAL_API
> CFLAGS += -O2 -D_FILE_OFFSET_BITS=64
> CFLAGS += $(WERROR_FLAGS)
> 
>+ifeq ($(CONFIG_RTE_LIBRTE_PMD_VHOST),y)
>+LDLIBS += -lrte_pmd_vhost
>+endif
>+
> include $(RTE_SDK)/mk/rte.extapp.mk
> 
> endif
>diff --git a/examples/vhost/main.c b/examples/vhost/main.c
>index ab649bf14..b3e331045 100644
>--- a/examples/vhost/main.c
>+++ b/examples/vhost/main.c
>@@ -24,6 +24,9 @@
> #include <rte_ip.h>
> #include <rte_tcp.h>
> #include <rte_pause.h>
>+#ifdef RTE_LIBRTE_PMD_VHOST
>+#include <rte_eth_vhost.h>
>+#endif
> 
> #include "main.h"
> 
>@@ -96,6 +99,9 @@ static int dequeue_zero_copy;
> 
> static int builtin_net_driver;
> 
>+/* Use vHost PMD instead of vHost library (Default) */
>+static int vhost_pmd;
>+
> /* Specify timeout (in useconds) between retries on RX. */
> static uint32_t burst_rx_delay_time = BURST_RX_WAIT_US;
> /* Specify the number of retries on RX. */
>@@ -182,6 +188,12 @@ struct mbuf_table lcore_tx_queue[RTE_MAX_LCORE];
> 				 / US_PER_S * BURST_TX_DRAIN_US)
> #define VLAN_HLEN       4
> 
>+static int
>+vhost_device_event_callback(uint16_t port_id,
>+				  enum rte_eth_event_type type,
>+				  void *param __rte_unused,
>+				  void *ret_param __rte_unused);
>+
> /*
>  * Builds up the correct configuration for VMDQ VLAN pool map
>  * according to the pool & queue limits.
>@@ -211,6 +223,151 @@ get_eth_conf(struct rte_eth_conf *eth_conf, uint32_t num_devices)
> 	return 0;
> }
> 
>+/*
>+ * Device removal before application exit
>+ * for the device to be re-used
>+ */
>+static void
>+unregister_device(int socket_num)

I think it's the updated version of previous unregister_drivers, why change
its name to unregister_device?

>+{
>+	int ret;
>+
>+	if (vhost_pmd) {
>+		char drv_name[RTE_ETH_NAME_MAX_LEN];
>+		struct vhost_dev *vdev = NULL;
>+		uint16_t port_id;
>+
>+		snprintf(drv_name, RTE_ETH_NAME_MAX_LEN,
>+						"net_vhost%d", socket_num);
>+		ret = rte_eth_dev_get_port_by_name(drv_name, &port_id);
>+		if (ret != 0)
>+			rte_exit(EXIT_FAILURE,
>+				"vhost device port id get failed.\n");

main func would call rte_exit after unregister_driver, so we could just call RTE_LOG
here as the non-vhost-pmd case.

>+
>+		TAILQ_FOREACH(vdev, &vhost_dev_list, global_vdev_entry) {
>+			if (vdev->eth_dev_id == port_id) {
>+				vdev->remove = 1;
>+				break;
>+			}
>+		}
>+
>+		/* Close the Ethernet device */
>+		rte_eth_dev_close(port_id);
>+	} else {
>+		ret = rte_vhost_driver_unregister(socket_files +
>+					socket_num * PATH_MAX);
>+		if (ret != 0)
>+			RTE_LOG(ERR, VHOST_CONFIG,
>+				"Fail to unregister vhost driver for %s.\n",
>+				socket_files + socket_num * PATH_MAX);
>+	}
>+}
>+
>+/*
>+ * Initialises a given port using global settings and with the rx buffers
>+ * coming from the mbuf_pool passed as parameter
>+ */
>+static inline int
>+port_init_v2(uint16_t portid)

What about naming it vhost_pmd_port_init to be more descriptive?

>+{
>+	struct rte_eth_rxconf rxq_conf;
>+	struct rte_eth_txconf txq_conf;
>+	struct rte_eth_dev_info dev_info;
>+	struct rte_eth_conf port_conf = {
>+		.rxmode = {
>+			.split_hdr_size = 0,
>+		},
>+		.txmode = {
>+			.mq_mode = ETH_MQ_TX_NONE,
>+		},
>+	};
>+	uint16_t nb_rxd, nb_txd;
>+	int ret = 0;
>+
>+	/* init port */
>+	printf("Initializing port %u... ", portid);
>+	fflush(stdout);
>+
>+	ret = rte_eth_dev_info_get(portid, &dev_info);
>+	if (ret != 0)
>+		rte_exit(EXIT_FAILURE,
>+			"Error during getting device (port %u) info: %s\n",
>+			portid, strerror(-ret));

main would check the return value of port_init and call ret_exit for failure case,
we can just call RTE_LOG here.

>+
>+	if (strncmp(dev_info.driver_name, "net_vhost",
>+				sizeof("net_vhost")) == 0)
>+		rte_eth_dev_callback_register(portid,
>+			RTE_ETH_EVENT_INTR_LSC,
>+			vhost_device_event_callback, NULL);
>+
>+	ret = rte_eth_dev_configure(portid, 1, 1, &port_conf);
>+	if (ret < 0)
>+		rte_exit(EXIT_FAILURE, "Cannot configure device: err=%d, port=%u\n",
>+			  ret, portid);
>+
>+	nb_rxd = RTE_TEST_RX_DESC_DEFAULT;
>+	nb_txd = RTE_TEST_TX_DESC_DEFAULT;
>+
>+	ret = rte_eth_dev_adjust_nb_rx_tx_desc(portid, &nb_rxd,
>+						   &nb_txd);
>+	if (ret < 0)
>+		rte_exit(EXIT_FAILURE,
>+			 "Cannot adjust number of descriptors: err=%d, port=%u\n",
>+			 ret, portid);
>+
>+	ret = rte_eth_macaddr_get(portid,
>+				  &vmdq_ports_eth_addr[portid]);
>+	if (ret < 0)
>+		rte_exit(EXIT_FAILURE,
>+			 "Cannot get MAC address: err=%d, port=%u\n",
>+			 ret, portid);
>+
>+	/* init RX queue */
>+	fflush(stdout);
>+	rxq_conf = dev_info.default_rxconf;
>+	rxq_conf.offloads = port_conf.rxmode.offloads;
>+	ret = rte_eth_rx_queue_setup(portid, 0, nb_rxd,
>+					 rte_eth_dev_socket_id(portid),
>+					 &rxq_conf,
>+					 mbuf_pool);
>+	if (ret < 0)
>+		rte_exit(EXIT_FAILURE, "rte_eth_rx_queue_setup:err=%d, port=%u\n",
>+			  ret, portid);
>+
>+	/* init TX queue */
>+	fflush(stdout);
>+	txq_conf = dev_info.default_txconf;
>+	txq_conf.offloads = port_conf.txmode.offloads;
>+	ret = rte_eth_tx_queue_setup(portid, 0, nb_txd,
>+			rte_eth_dev_socket_id(portid),
>+			&txq_conf);
>+	if (ret < 0)
>+		rte_exit(EXIT_FAILURE, "rte_eth_tx_queue_setup:err=%d, port=%u\n",
>+			ret, portid);
>+
>+	/* Start device */
>+	ret = rte_eth_dev_start(portid);
>+	if (ret < 0)
>+		rte_exit(EXIT_FAILURE, "rte_eth_dev_start:err=%d, port=%u\n",
>+				ret, portid);
>+
>+	if (promiscuous) {
>+		ret = rte_eth_promiscuous_enable(portid);
>+		if ((ret != 0) && (ret != -ENOTSUP)) {
>+			uint8_t i;
>+
>+			for (i = 0; i < nb_sockets; i++)
>+				unregister_device(i);
>+
>+			rte_exit(EXIT_FAILURE,
>+				 "rte_eth_promiscuous_enable:err=%s, port=%u\n",
>+				 rte_strerror(-ret), portid);
>+		}
>+	}
>+
>+	return 0;
>+}
>+
> /*
>  * Initialises a given port using global settings and with the rx buffers
>  * coming from the mbuf_pool passed as parameter
>@@ -461,7 +618,8 @@ us_vhost_usage(const char *prgname)
> 	"		--tx-csum [0|1] disable/enable TX checksum offload.\n"
> 	"		--tso [0|1] disable/enable TCP segment offload.\n"
> 	"		--client register a vhost-user socket as client mode.\n"
>-	"		--dequeue-zero-copy enables dequeue zero copy\n",
>+	"		--dequeue-zero-copy enables dequeue zero copy.\n"
>+	"		--use-vhost-pmd enables vHost PMD instead of vHost library\n",
> 	       prgname);
> }
> 
>@@ -488,6 +646,7 @@ us_vhost_parse_args(int argc, char **argv)
> 		{"client", no_argument, &client_mode, 1},
> 		{"dequeue-zero-copy", no_argument, &dequeue_zero_copy, 1},
> 		{"builtin-net-driver", no_argument, &builtin_net_driver, 1},
>+		{"use-vhost-pmd", no_argument, &vhost_pmd, 1},
> 		{NULL, 0, 0, 0},
> 	};
> 
>@@ -1047,37 +1206,61 @@ drain_eth_rx(struct vhost_dev *vdev)
> 	if (!rx_count)
> 		return;
> 
>-	/*
>-	 * When "enable_retry" is set, here we wait and retry when there
>-	 * is no enough free slots in the queue to hold @rx_count packets,
>-	 * to diminish packet loss.
>-	 */
>-	if (enable_retry &&
>-	    unlikely(rx_count > rte_vhost_avail_entries(vdev->vid,
>-			VIRTIO_RXQ))) {
>-		uint32_t retry;
>-
>-		for (retry = 0; retry < burst_rx_retry_num; retry++) {
>-			rte_delay_us(burst_rx_delay_time);
>-			if (rx_count <= rte_vhost_avail_entries(vdev->vid,
>-					VIRTIO_RXQ))
>-				break;
>+	if (vhost_pmd) {
>+		enqueue_count = rte_eth_tx_burst(vdev->eth_dev_id, 0,
>+			pkts, rx_count);
>+		if (unlikely(enqueue_count < rx_count)) {
>+			uint32_t retry, pending = rx_count - enqueue_count;
>+			for (retry = 0; retry < burst_rx_retry_num; retry++) {
>+				rte_delay_us(burst_rx_delay_time);
>+				enqueue_count += rte_eth_tx_burst(
>+					vdev->eth_dev_id, 0,
>+					(pkts + enqueue_count), pending);
>+				pending = rx_count - enqueue_count;
>+
>+				if (enqueue_count == rx_count)
>+					break;
>+			}
>+			/* Drop the remaining packets */
>+			uint32_t idx;

This mixed declaration and code statement.

>+			for (idx = enqueue_count; idx < rx_count; idx++)
>+				rte_pktmbuf_free(pkts[idx]);
> 		}
>-	}
>-
>-	if (builtin_net_driver) {
>-		enqueue_count = vs_enqueue_pkts(vdev, VIRTIO_RXQ,
>-						pkts, rx_count);
> 	} else {
>-		enqueue_count = rte_vhost_enqueue_burst(vdev->vid, VIRTIO_RXQ,
>-						pkts, rx_count);
>+		/*
>+		 * When "enable_retry" is set, here we wait and retry
>+		 * when there is no enough free slots in the queue to
>+		 * hold @rx_count packets, to diminish packet loss.
>+		 */
>+		if (enable_retry &&
>+			unlikely(rx_count > rte_vhost_avail_entries(
>+				vdev->vid, VIRTIO_RXQ))) {
>+			uint32_t retry;
>+
>+			for (retry = 0; retry <
>+				burst_rx_retry_num; retry++) {
>+				rte_delay_us(burst_rx_delay_time);
>+				if (rx_count <= rte_vhost_avail_entries(
>+					vdev->vid, VIRTIO_RXQ))
>+					break;
>+			}
>+		}
>+
>+		if (builtin_net_driver) {
>+			enqueue_count = vs_enqueue_pkts(vdev, VIRTIO_RXQ,
>+							pkts, rx_count);
>+		} else {
>+			enqueue_count = rte_vhost_enqueue_burst(vdev->vid,
>+				VIRTIO_RXQ,	pkts, rx_count);
>+		}
>+
>+		free_pkts(pkts, rx_count);
> 	}
>+
> 	if (enable_stats) {
> 		rte_atomic64_add(&vdev->stats.rx_total_atomic, rx_count);
> 		rte_atomic64_add(&vdev->stats.rx_atomic, enqueue_count);
> 	}
>-
>-	free_pkts(pkts, rx_count);
> }
> 
> static __rte_always_inline void
>@@ -1087,12 +1270,20 @@ drain_virtio_tx(struct vhost_dev *vdev)
> 	uint16_t count;
> 	uint16_t i;
> 
>-	if (builtin_net_driver) {
>-		count = vs_dequeue_pkts(vdev, VIRTIO_TXQ, mbuf_pool,
>-					pkts, MAX_PKT_BURST);
>+	if (vhost_pmd) {
>+		count = rte_eth_rx_burst(vdev->eth_dev_id,
>+					0, pkts, MAX_PKT_BURST);
>+		if (!count)
>+			return;
>+
> 	} else {
>-		count = rte_vhost_dequeue_burst(vdev->vid, VIRTIO_TXQ,
>-					mbuf_pool, pkts, MAX_PKT_BURST);
>+		if (builtin_net_driver) {
>+			count = vs_dequeue_pkts(vdev, VIRTIO_TXQ, mbuf_pool,
>+						pkts, MAX_PKT_BURST);
>+		} else {
>+			count = rte_vhost_dequeue_burst(vdev->vid, VIRTIO_TXQ,
>+						mbuf_pool, pkts, MAX_PKT_BURST);
>+		}
> 	}
> 
> 	/* setup VMDq for the first packet */
>@@ -1291,6 +1482,91 @@ static const struct vhost_device_ops virtio_net_device_ops =
> 	.destroy_device = destroy_device,
> };
> 
>+static int
>+vhost_device_attach_callback(uint16_t port_id)
>+{
>+	int lcore, core_add = 0, vid = -1;
>+	uint32_t device_num_min = num_devices;
>+	struct vhost_dev *vdev;
>+
>+#ifdef RTE_LIBRTE_PMD_VHOST
>+	vid = rte_eth_vhost_get_vid_from_port_id(port_id);
>+#endif
>+
>+	vdev = rte_zmalloc("vhost device", sizeof(*vdev), RTE_CACHE_LINE_SIZE);
>+	if (vdev == NULL) {
>+		RTE_LOG(INFO, VHOST_DATA,
>+			"(%d) couldn't allocate memory for vhost dev\n",
>+			vid);
>+		return -1;
>+	}
>+
>+	if (builtin_net_driver)
>+		vs_vhost_net_setup(vdev);
>+
>+	TAILQ_INSERT_TAIL(&vhost_dev_list, vdev, global_vdev_entry);
>+	vdev->vmdq_rx_q = vid * queues_per_pool + vmdq_queue_base;
>+
>+	/*reset ready flag*/
>+	vdev->ready = DEVICE_MAC_LEARNING;
>+	vdev->remove = 0;
>+
>+	vdev->vid = vid;
>+	vdev->eth_dev_id = port_id;
>+
>+	/* Find a suitable lcore to add the device. */
>+	RTE_LCORE_FOREACH_SLAVE(lcore) {
>+		if (lcore_info[lcore].device_num < device_num_min) {
>+			device_num_min = lcore_info[lcore].device_num;
>+			core_add = lcore;
>+		}
>+	}
>+	vdev->coreid = core_add;
>+
>+	TAILQ_INSERT_TAIL(&lcore_info[vdev->coreid].vdev_list, vdev,
>+			  lcore_vdev_entry);
>+	lcore_info[vdev->coreid].device_num++;
>+
>+	return 0;
>+}
>+
>+int
>+vhost_device_event_callback(uint16_t port_id,
>+				enum rte_eth_event_type type,
>+				void *param __rte_unused,
>+				void *ret_param __rte_unused)
>+{
>+	struct rte_eth_link link;
>+	int vid = -1;
>+
>+	if (type == RTE_ETH_EVENT_INTR_LSC) {
>+		rte_eth_link_get_nowait(port_id, &link);
>+
>+		if (link.link_status) {
>+			RTE_LOG(INFO, VHOST_DATA,
>+				"Port %d Link Up - speed %u Mbps - %s\n",
>+				port_id, (unsigned int) link.link_speed,
>+				(link.link_duplex == ETH_LINK_FULL_DUPLEX)
>+				? "full-duplex" : "half-duplex");
>+			if (vhost_device_attach_callback(port_id) != 0) {
>+				RTE_LOG(ERR, VHOST_DATA,
>+					"vhost dev (%d) attach callback failed\n",
>+					port_id);
>+				return -1;
>+			}
>+		} else {
>+			RTE_LOG(INFO, VHOST_DATA, "Port %d Link Down\n",
>+					port_id);
>+#ifdef RTE_LIBRTE_PMD_VHOST
>+			vid = rte_eth_vhost_get_vid_from_port_id(port_id);
>+#endif
>+			destroy_device(vid);
>+		}
>+	}
>+
>+	return 0;
>+}
>+
> /*
>  * This is a thread will wake up after a period to print stats if the user has
>  * enabled them.
>@@ -1339,26 +1615,15 @@ print_stats(__rte_unused void *arg)
> 	return NULL;
> }
> 
>-static void
>-unregister_drivers(int socket_num)
>-{
>-	int i, ret;
>-
>-	for (i = 0; i < socket_num; i++) {
>-		ret = rte_vhost_driver_unregister(socket_files + i * PATH_MAX);
>-		if (ret != 0)
>-			RTE_LOG(ERR, VHOST_CONFIG,
>-				"Fail to unregister vhost driver for %s.\n",
>-				socket_files + i * PATH_MAX);
>-	}
>-}
>-
> /* When we receive a INT signal, unregister vhost driver */
> static void
> sigint_handler(__rte_unused int signum)
> {
> 	/* Unregister vhost driver. */
>-	unregister_drivers(nb_sockets);
>+	uint8_t i;
>+
>+	for (i = 0; i < nb_sockets; i++)
>+		unregister_device(i);
> 
> 	exit(0);
> }
>@@ -1441,6 +1706,14 @@ main(int argc, char *argv[])
> 	if (ret < 0)
> 		rte_exit(EXIT_FAILURE, "Invalid argument\n");
> 
>+#ifndef RTE_LIBRTE_PMD_VHOST
>+	if (vhost_pmd == 1) {
>+		RTE_LOG(ERR, VHOST_CONFIG, "Use vHost PMD is not supported\n");
>+		rte_exit(EXIT_FAILURE, "vHost PMD should be enabled in"
>+			" config file\n");
>+	}
>+#endif
>+
> 	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
> 		TAILQ_INIT(&lcore_info[lcore_id].vdev_list);
> 
>@@ -1517,52 +1790,86 @@ main(int argc, char *argv[])
> 	/* Register vhost user driver to handle vhost messages. */
> 	for (i = 0; i < nb_sockets; i++) {
> 		char *file = socket_files + i * PATH_MAX;
>-		ret = rte_vhost_driver_register(file, flags);
>-		if (ret != 0) {
>-			unregister_drivers(i);
>-			rte_exit(EXIT_FAILURE,
>-				"vhost driver register failure.\n");
>-		}
> 
>-		if (builtin_net_driver)
>-			rte_vhost_driver_set_features(file, VIRTIO_NET_FEATURES);
>+		if (vhost_pmd) {
>+			char dev_name[PATH_MAX];
>+			char drv_name[RTE_ETH_NAME_MAX_LEN];
>+			uint16_t port;
>+
>+			snprintf(drv_name, RTE_ETH_NAME_MAX_LEN,
>+				"net_vhost%d", i);
>+			snprintf(dev_name, PATH_MAX, "%s,"
>+				"iface=%s,client=%d,tso=%d,"
>+				"dequeue-zero-copy=%d",
>+				drv_name, file, client_mode,
>+				enable_tso, dequeue_zero_copy);
>+
>+			ret = rte_dev_probe(dev_name);

I am wondering whether we can use vhost-pmd by specifying net_vhost vdev in eal options.

>+			if (ret != 0) {
>+				rte_exit(EXIT_FAILURE,
>+					"vhost user device probe failed\n");
>+			}
>+			ret = rte_eth_dev_get_port_by_name(drv_name, &port);
>+			if (ret != 0) {
>+				unregister_device(i);

Here unregister_device only deals with one registered vhost driver, but we need
to get rid of all registered ones before rte_exit, right?
And same for below 2 unregister.

>+				rte_exit(EXIT_FAILURE,
>+					"vhost device port id get failed.\n");
>+			}
>+			ret = port_init_v2(port);
>+			if (ret != 0) {
>+				unregister_device(i);
>+				rte_exit(EXIT_FAILURE,
>+					"vhost device port initialization failed.\n");
>+			}
>+		} else {
>+			ret = rte_vhost_driver_register(file, flags);
>+			if (ret != 0) {
>+				unregister_device(i);
>+				rte_exit(EXIT_FAILURE,
>+					"vhost driver register failure.\n");
>+			}
> 
>-		if (mergeable == 0) {
>-			rte_vhost_driver_disable_features(file,
>-				1ULL << VIRTIO_NET_F_MRG_RXBUF);
>-		}
>+			if (builtin_net_driver)
>+				rte_vhost_driver_set_features(file,
>+					VIRTIO_NET_FEATURES);
> 
>-		if (enable_tx_csum == 0) {
>-			rte_vhost_driver_disable_features(file,
>-				1ULL << VIRTIO_NET_F_CSUM);
>-		}
>+			if (mergeable == 0) {
>+				rte_vhost_driver_disable_features(file,
>+					1ULL << VIRTIO_NET_F_MRG_RXBUF);
>+			}
> 
>-		if (enable_tso == 0) {
>-			rte_vhost_driver_disable_features(file,
>-				1ULL << VIRTIO_NET_F_HOST_TSO4);
>-			rte_vhost_driver_disable_features(file,
>-				1ULL << VIRTIO_NET_F_HOST_TSO6);
>-			rte_vhost_driver_disable_features(file,
>-				1ULL << VIRTIO_NET_F_GUEST_TSO4);
>-			rte_vhost_driver_disable_features(file,
>-				1ULL << VIRTIO_NET_F_GUEST_TSO6);
>-		}
>+			if (enable_tx_csum == 0) {
>+				rte_vhost_driver_disable_features(file,
>+					1ULL << VIRTIO_NET_F_CSUM);
>+			}
> 
>-		if (promiscuous) {
>-			rte_vhost_driver_enable_features(file,
>-				1ULL << VIRTIO_NET_F_CTRL_RX);
>-		}
>+			if (enable_tso == 0) {
>+				rte_vhost_driver_disable_features(file,
>+					1ULL << VIRTIO_NET_F_HOST_TSO4);
>+				rte_vhost_driver_disable_features(file,
>+					1ULL << VIRTIO_NET_F_HOST_TSO6);
>+				rte_vhost_driver_disable_features(file,
>+					1ULL << VIRTIO_NET_F_GUEST_TSO4);
>+				rte_vhost_driver_disable_features(file,
>+					1ULL << VIRTIO_NET_F_GUEST_TSO6);
>+			}
> 
>-		ret = rte_vhost_driver_callback_register(file,
>-			&virtio_net_device_ops);
>-		if (ret != 0) {
>-			rte_exit(EXIT_FAILURE,
>-				"failed to register vhost driver callbacks.\n");
>-		}
>+			if (promiscuous) {
>+				rte_vhost_driver_enable_features(file,
>+					1ULL << VIRTIO_NET_F_CTRL_RX);
>+			}
> 
>-		if (rte_vhost_driver_start(file) < 0) {
>-			rte_exit(EXIT_FAILURE,
>-				"failed to start vhost driver.\n");
>+			ret = rte_vhost_driver_callback_register(file,
>+				&virtio_net_device_ops);
>+			if (ret != 0) {
>+				rte_exit(EXIT_FAILURE,
>+					"failed to register vhost driver callbacks.\n");
>+			}
>+
>+			if (rte_vhost_driver_start(file) < 0) {
>+				rte_exit(EXIT_FAILURE,
>+					"failed to start vhost driver.\n");
>+			}
> 		}
> 	}
> 
>diff --git a/examples/vhost/main.h b/examples/vhost/main.h
>index 7cba0edbf..023f43891 100644
>--- a/examples/vhost/main.h
>+++ b/examples/vhost/main.h
>@@ -48,6 +48,7 @@ struct vhost_dev {
> 	volatile uint8_t remove;
> 
> 	int vid;
>+	uint16_t eth_dev_id;
> 	uint64_t features;
> 	size_t hdr_len;
> 	uint16_t nr_vrings;
>diff --git a/examples/vhost/meson.build b/examples/vhost/meson.build
>index 872d51153..158add5eb 100644
>--- a/examples/vhost/meson.build
>+++ b/examples/vhost/meson.build
>@@ -9,7 +9,8 @@
> if not is_linux
> 	build = false
> endif
>-deps += 'vhost'
>+build = dpdk_conf.has('RTE_LIBRTE_PMD_VHOST')
>+deps += 'pmd_vhost'
> allow_experimental_apis = true
> sources = files(
> 	'main.c', 'virtio_net.c'
>-- 
>2.17.1
>