To be able to manage buffers inside a shared memory provided
by a VM via a vhost-user interface, we cannot rely on the fact
that buffers are located in a pre-defined memory area and use
a base address and a 32bit offset to address them.

We need a 64bit address, so replace struct desc by struct iovec
and update range checking.

Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>
---
 packet.c | 80 ++++++++++++++++++++++++++++++--------------------------
 packet.h | 14 ++--------
 2 files changed, 45 insertions(+), 49 deletions(-)

diff --git a/packet.c b/packet.c
index ccfc84607709..37489961a37e 100644
--- a/packet.c
+++ b/packet.c
@@ -22,6 +22,35 @@
 #include "util.h"
 #include "log.h"
 
+/**
+ * packet_check_range() - Check if a packet memory range is valid
+ * @p:		Packet pool
+ * @offset:	Offset of data range in packet descriptor
+ * @len:	Length of desired data range
+ * @start:	Start of the packet descriptor
+ * @func:	For tracing: name of calling function
+ * @line:	For tracing: caller line of function call
+ *
+ * Return: 0 if the range is valid, -1 otherwise
+ */
+static int packet_check_range(const struct pool *p, size_t offset, size_t len,
+			      const char *start, const char *func, int line)
+{
+	if (start < p->buf) {
+		trace("packet start %p before buffer start %p, "
+		      "%s:%i", (void *)start, (void *)p->buf, func, line);
+		return -1;
+	}
+
+	if (start + len + offset > p->buf + p->buf_size) {
+		trace("packet offset plus length %lu from size %lu, "
+		      "%s:%i", start - p->buf + len + offset,
+		      p->buf_size, func, line);
+		return -1;
+	}
+
+	return 0;
+}
 /**
  * packet_add_do() - Add data as packet descriptor to given pool
  * @p:		Existing pool
@@ -41,34 +70,16 @@ void packet_add_do(struct pool *p, size_t len, const char *start,
 		return;
 	}
 
-	if (start < p->buf) {
-		trace("add packet start %p before buffer start %p, %s:%i",
-		      (void *)start, (void *)p->buf, func, line);
+	if (packet_check_range(p, 0, len, start, func, line))
 		return;
-	}
-
-	if (start + len > p->buf + p->buf_size) {
-		trace("add packet start %p, length: %zu, buffer end %p, %s:%i",
-		      (void *)start, len, (void *)(p->buf + p->buf_size),
-		      func, line);
-		return;
-	}
 
 	if (len > UINT16_MAX) {
 		trace("add packet length %zu, %s:%i", len, func, line);
 		return;
 	}
 
-#if UINTPTR_MAX == UINT64_MAX
-	if ((uintptr_t)start - (uintptr_t)p->buf > UINT32_MAX) {
-		trace("add packet start %p, buffer start %p, %s:%i",
-		      (void *)start, (void *)p->buf, func, line);
-		return;
-	}
-#endif
-
-	p->pkt[idx].offset = start - p->buf;
-	p->pkt[idx].len = len;
+	p->pkt[idx].iov_base = (void *)start;
+	p->pkt[idx].iov_len = len;
 
 	p->count++;
 }
@@ -96,36 +107,31 @@ void *packet_get_do(const struct pool *p, size_t idx, size_t offset,
 		return NULL;
 	}
 
-	if (len > UINT16_MAX || len + offset > UINT32_MAX) {
+	if (len > UINT16_MAX) {
 		if (func) {
-			trace("packet data length %zu, offset %zu, %s:%i",
-			      len, offset, func, line);
+			trace("packet data length %zu, %s:%i",
+			      len, func, line);
 		}
 		return NULL;
 	}
 
-	if (p->pkt[idx].offset + len + offset > p->buf_size) {
+	if (len + offset > p->pkt[idx].iov_len) {
 		if (func) {
-			trace("packet offset plus length %zu from size %zu, "
-			      "%s:%i", p->pkt[idx].offset + len + offset,
-			      p->buf_size, func, line);
+			trace("data length %zu, offset %zu from length %zu, "
+			      "%s:%i", len, offset, p->pkt[idx].iov_len,
+			      func, line);
 		}
 		return NULL;
 	}
 
-	if (len + offset > p->pkt[idx].len) {
-		if (func) {
-			trace("data length %zu, offset %zu from length %u, "
-			      "%s:%i", len, offset, p->pkt[idx].len,
-			      func, line);
-		}
+	if (packet_check_range(p, offset, len, p->pkt[idx].iov_base,
+			       func, line))
 		return NULL;
-	}
 
 	if (left)
-		*left = p->pkt[idx].len - offset - len;
+		*left = p->pkt[idx].iov_len - offset - len;
 
-	return p->buf + p->pkt[idx].offset + offset;
+	return (char *)p->pkt[idx].iov_base + offset;
 }
 
 /**
diff --git a/packet.h b/packet.h
index a784b07bbed5..8377dcf678bb 100644
--- a/packet.h
+++ b/packet.h
@@ -6,16 +6,6 @@
 #ifndef PACKET_H
 #define PACKET_H
 
-/**
- * struct desc - Generic offset-based descriptor within buffer
- * @offset:	Offset of descriptor relative to buffer start, 32-bit limit
- * @len:	Length of descriptor, host order, 16-bit limit
- */
-struct desc {
-	uint32_t offset;
-	uint16_t len;
-};
-
 /**
  * struct pool - Generic pool of packets stored in a buffer
  * @buf:	Buffer storing packet descriptors
@@ -29,7 +19,7 @@ struct pool {
 	size_t buf_size;
 	size_t size;
 	size_t count;
-	struct desc pkt[1];
+	struct iovec pkt[1];
 };
 
 void packet_add_do(struct pool *p, size_t len, const char *start,
@@ -54,7 +44,7 @@ struct _name ## _t {							\
 	size_t buf_size;						\
 	size_t size;							\
 	size_t count;							\
-	struct desc pkt[_size];						\
+	struct iovec pkt[_size];					\
 }
 
 #define PACKET_POOL_INIT_NOCAST(_size, _buf, _buf_size)			\
-- 
2.47.0

Add vhost_user.c and vhost_user.h that define the functions needed
to implement vhost-user backend.

Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
---
 Makefile     |   4 +-
 vhost_user.c | 970 +++++++++++++++++++++++++++++++++++++++++++++++++++
 vhost_user.h | 208 +++++++++++
 virtio.h     |   1 +
 4 files changed, 1181 insertions(+), 2 deletions(-)
 create mode 100644 vhost_user.c
 create mode 100644 vhost_user.h

diff --git a/Makefile b/Makefile
index 9b61a47e50fc..bcb084e66e4d 100644
--- a/Makefile
+++ b/Makefile
@@ -37,7 +37,7 @@ FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
 PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c flow.c fwd.c \
 	icmp.c igmp.c inany.c iov.c ip.c isolation.c lineread.c log.c mld.c \
 	ndp.c netlink.c packet.c passt.c pasta.c pcap.c pif.c tap.c tcp.c \
-	tcp_buf.c tcp_splice.c udp.c udp_flow.c util.c virtio.c
+	tcp_buf.c tcp_splice.c udp.c udp_flow.c util.c vhost_user.c virtio.c
 QRAP_SRCS = qrap.c
 SRCS = $(PASST_SRCS) $(QRAP_SRCS)
 
@@ -47,7 +47,7 @@ PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h flow.h
fwd.h \
 	flow_table.h icmp.h icmp_flow.h inany.h iov.h ip.h isolation.h \
 	lineread.h log.h ndp.h netlink.h packet.h passt.h pasta.h pcap.h pif.h \
 	siphash.h tap.h tcp.h tcp_buf.h tcp_conn.h tcp_internal.h tcp_splice.h \
-	udp.h udp_flow.h util.h virtio.h
+	udp.h udp_flow.h util.h vhost_user.h virtio.h
 HEADERS = $(PASST_HEADERS) seccomp.h
 
 C := \#include <sys/random.h>\nint main(){int a=getrandom(0, 0, 0);}
diff --git a/vhost_user.c b/vhost_user.c
new file mode 100644
index 000000000000..89627a227ff1
--- /dev/null
+++ b/vhost_user.c
@@ -0,0 +1,970 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * vhost-user API, command management and virtio interface
+ *
+ * Copyright Red Hat
+ * Author: Laurent Vivier &lt;lvivier(a)redhat.com&gt;
+ *
+ * Some parts from QEMU subprojects/libvhost-user/libvhost-user.c
+ * licensed under the following terms:
+ *
+ * Copyright IBM, Corp. 2007
+ * Copyright (c) 2016 Red Hat, Inc.
+ *
+ * Authors:
+ *  Anthony Liguori &lt;aliguori(a)us.ibm.com&gt;
+ *  Marc-André Lureau &lt;mlureau(a)redhat.com&gt;
+ *  Victor Kaplansky &lt;victork(a)redhat.com&gt;
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <string.h>
+#include <assert.h>
+#include <stdbool.h>
+#include <inttypes.h>
+#include <time.h>
+#include <net/ethernet.h>
+#include <netinet/in.h>
+#include <sys/epoll.h>
+#include <sys/eventfd.h>
+#include <sys/mman.h>
+#include <linux/vhost_types.h>
+#include <linux/virtio_net.h>
+
+#include "util.h"
+#include "passt.h"
+#include "tap.h"
+#include "vhost_user.h"
+#include "pcap.h"
+
+/* vhost-user version we are compatible with */
+#define VHOST_USER_VERSION 1
+
+/**
+ * vu_print_capabilities() - print vhost-user capabilities
+ * 			     this is part of the vhost-user backend
+ * 			     convention.
+ */
+/* cppcheck-suppress unusedFunction */
+void vu_print_capabilities(void)
+{
+	info("{");
+	info("  \"type\": \"net\"");
+	info("}");
+	exit(EXIT_SUCCESS);
+}
+
+/**
+ * vu_request_to_string() - convert a vhost-user request number to its name
+ * @req:	request number
+ *
+ * Return: the name of request number
+ */
+static const char *vu_request_to_string(unsigned int req)
+{
+	if (req < VHOST_USER_MAX) {
+#define REQ(req) [req] = #req
+		static const char * const vu_request_str[VHOST_USER_MAX] = {
+			REQ(VHOST_USER_NONE),
+			REQ(VHOST_USER_GET_FEATURES),
+			REQ(VHOST_USER_SET_FEATURES),
+			REQ(VHOST_USER_SET_OWNER),
+			REQ(VHOST_USER_RESET_OWNER),
+			REQ(VHOST_USER_SET_MEM_TABLE),
+			REQ(VHOST_USER_SET_LOG_BASE),
+			REQ(VHOST_USER_SET_LOG_FD),
+			REQ(VHOST_USER_SET_VRING_NUM),
+			REQ(VHOST_USER_SET_VRING_ADDR),
+			REQ(VHOST_USER_SET_VRING_BASE),
+			REQ(VHOST_USER_GET_VRING_BASE),
+			REQ(VHOST_USER_SET_VRING_KICK),
+			REQ(VHOST_USER_SET_VRING_CALL),
+			REQ(VHOST_USER_SET_VRING_ERR),
+			REQ(VHOST_USER_GET_PROTOCOL_FEATURES),
+			REQ(VHOST_USER_SET_PROTOCOL_FEATURES),
+			REQ(VHOST_USER_GET_QUEUE_NUM),
+			REQ(VHOST_USER_SET_VRING_ENABLE),
+			REQ(VHOST_USER_SEND_RARP),
+			REQ(VHOST_USER_NET_SET_MTU),
+			REQ(VHOST_USER_SET_BACKEND_REQ_FD),
+			REQ(VHOST_USER_IOTLB_MSG),
+			REQ(VHOST_USER_SET_VRING_ENDIAN),
+			REQ(VHOST_USER_GET_CONFIG),
+			REQ(VHOST_USER_SET_CONFIG),
+			REQ(VHOST_USER_POSTCOPY_ADVISE),
+			REQ(VHOST_USER_POSTCOPY_LISTEN),
+			REQ(VHOST_USER_POSTCOPY_END),
+			REQ(VHOST_USER_GET_INFLIGHT_FD),
+			REQ(VHOST_USER_SET_INFLIGHT_FD),
+			REQ(VHOST_USER_GPU_SET_SOCKET),
+			REQ(VHOST_USER_VRING_KICK),
+			REQ(VHOST_USER_GET_MAX_MEM_SLOTS),
+			REQ(VHOST_USER_ADD_MEM_REG),
+			REQ(VHOST_USER_REM_MEM_REG),
+		};
+#undef REQ
+		return vu_request_str[req];
+	}
+
+	return "unknown";
+}
+
+/**
+ * qva_to_va() -  Translate front-end (QEMU) virtual address to our virtual
+ * 		  address
+ * @dev:		vhost-user device
+ * @qemu_addr:		front-end userspace address
+ *
+ * Return: the memory address in our process virtual address space.
+ */
+static void *qva_to_va(struct vu_dev *dev, uint64_t qemu_addr)
+{
+	unsigned int i;
+
+	/* Find matching memory region.  */
+	for (i = 0; i < dev->nregions; i++) {
+		const struct vu_dev_region *r = &dev->regions[i];
+
+		if ((qemu_addr >= r->qva) && (qemu_addr < (r->qva + r->size)))
{
+			/* NOLINTNEXTLINE(performance-no-int-to-ptr) */
+			return (void *)(qemu_addr - r->qva + r->mmap_addr +
+					r->mmap_offset);
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * vmsg_close_fds() - Close all file descriptors of a given message
+ * @vmsg:	vhost-user message with the list of the file descriptors
+ */
+static void vmsg_close_fds(const struct vhost_user_msg *vmsg)
+{
+	int i;
+
+	for (i = 0; i < vmsg->fd_num; i++)
+		close(vmsg->fds[i]);
+}
+
+/**
+ * vu_remove_watch() - Remove a file descriptor from our passt epoll
+ * 		       file descriptor
+ * @vdev:	vhost-user device
+ * @fd:		file descriptor to remove
+ */
+static void vu_remove_watch(const struct vu_dev *vdev, int fd)
+{
+	/* Placeholder to add passt related code */
+	(void)vdev;
+	(void)fd;
+}
+
+/**
+ * vmsg_set_reply_u64() - Set reply payload.u64 and clear request flags
+ * 			  and fd_num
+ * @vmsg:	vhost-user message
+ * @val:	64-bit value to reply
+ */
+static void vmsg_set_reply_u64(struct vhost_user_msg *vmsg, uint64_t val)
+{
+	vmsg->hdr.flags = 0; /* defaults will be set by vu_send_reply() */
+	vmsg->hdr.size = sizeof(vmsg->payload.u64);
+	vmsg->payload.u64 = val;
+	vmsg->fd_num = 0;
+}
+
+/**
+ * vu_message_read_default() - Read incoming vhost-user message from the
+ * 			       front-end
+ * @conn_fd:	vhost-user command socket
+ * @vmsg:	vhost-user message
+ *
+ * Return:  0 if recvmsg() has been interrupted or if there's no data to read,
+ *          1 if a message has been received
+ */
+static int vu_message_read_default(int conn_fd, struct vhost_user_msg *vmsg)
+{
+	char control[CMSG_SPACE(VHOST_MEMORY_BASELINE_NREGIONS *
+		     sizeof(int))] = { 0 };
+	struct iovec iov = {
+		.iov_base = (char *)vmsg,
+		.iov_len = VHOST_USER_HDR_SIZE,
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+		.msg_control = control,
+		.msg_controllen = sizeof(control),
+	};
+	ssize_t ret, sz_payload;
+	struct cmsghdr *cmsg;
+
+	ret = recvmsg(conn_fd, &msg, MSG_DONTWAIT);
+	if (ret < 0) {
+		if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
+			return 0;
+		die_perror("vhost-user message receive (recvmsg)");
+	}
+
+	vmsg->fd_num = 0;
+	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
+	     cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+		if (cmsg->cmsg_level == SOL_SOCKET &&
+		    cmsg->cmsg_type == SCM_RIGHTS) {
+			size_t fd_size;
+
+			ASSERT(cmsg->cmsg_len >= CMSG_LEN(0));
+			fd_size = cmsg->cmsg_len - CMSG_LEN(0);
+			ASSERT(fd_size <= sizeof(vmsg->fds));
+			vmsg->fd_num = fd_size / sizeof(int);
+			memcpy(vmsg->fds, CMSG_DATA(cmsg), fd_size);
+			break;
+		}
+	}
+
+	sz_payload = vmsg->hdr.size;
+	if ((size_t)sz_payload > sizeof(vmsg->payload)) {
+		die("vhost-user message request too big: %d,"
+			 " size: vmsg->size: %zd, "
+			 "while sizeof(vmsg->payload) = %zu",
+			 vmsg->hdr.request, sz_payload, sizeof(vmsg->payload));
+	}
+
+	if (sz_payload) {
+		do
+			ret = recv(conn_fd, &vmsg->payload, sz_payload, 0);
+		while (ret < 0 && errno == EINTR);
+
+		if (ret < 0)
+			die_perror("vhost-user message receive");
+
+		if (ret == 0)
+			die("EOF on vhost-user message receive");
+
+		if (ret < sz_payload)
+			die("Short-read on vhost-user message receive");
+	}
+
+	return 1;
+}
+
+/**
+ * vu_message_write() - Send a message to the front-end
+ * @conn_fd:	vhost-user command socket
+ * @vmsg:	vhost-user message
+ *
+ * #syscalls:vu sendmsg
+ */
+static void vu_message_write(int conn_fd, struct vhost_user_msg *vmsg)
+{
+	char control[CMSG_SPACE(VHOST_MEMORY_BASELINE_NREGIONS * sizeof(int))] = { 0 };
+	struct iovec iov = {
+		.iov_base = (char *)vmsg,
+		.iov_len = VHOST_USER_HDR_SIZE + vmsg->hdr.size,
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+		.msg_control = control,
+	};
+	int rc;
+
+	ASSERT(vmsg->fd_num <= VHOST_MEMORY_BASELINE_NREGIONS);
+	if (vmsg->fd_num > 0) {
+		size_t fdsize = vmsg->fd_num * sizeof(int);
+		struct cmsghdr *cmsg;
+
+		msg.msg_controllen = CMSG_SPACE(fdsize);
+		cmsg = CMSG_FIRSTHDR(&msg);
+		cmsg->cmsg_len = CMSG_LEN(fdsize);
+		cmsg->cmsg_level = SOL_SOCKET;
+		cmsg->cmsg_type = SCM_RIGHTS;
+		memcpy(CMSG_DATA(cmsg), vmsg->fds, fdsize);
+	}
+
+	do
+		rc = sendmsg(conn_fd, &msg, 0);
+	while (rc < 0 && errno == EINTR);
+
+	if (rc < 0)
+		die_perror("vhost-user message send");
+
+	if ((uint32_t)rc < VHOST_USER_HDR_SIZE + vmsg->hdr.size)
+		die("EOF on vhost-user message send");
+}
+
+/**
+ * vu_send_reply() - Update message flags and send it to front-end
+ * @conn_fd:	vhost-user command socket
+ * @vmsg:	vhost-user message
+ */
+static void vu_send_reply(int conn_fd, struct vhost_user_msg *msg)
+{
+	msg->hdr.flags &= ~VHOST_USER_VERSION_MASK;
+	msg->hdr.flags |= VHOST_USER_VERSION;
+	msg->hdr.flags |= VHOST_USER_REPLY_MASK;
+
+	vu_message_write(conn_fd, msg);
+}
+
+/**
+ * vu_get_features_exec() - Provide back-end features bitmask to front-end
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: True as a reply is requested
+ */
+static bool vu_get_features_exec(struct vu_dev *vdev,
+				 struct vhost_user_msg *msg)
+{
+	uint64_t features =
+		1ULL << VIRTIO_F_VERSION_1 |
+		1ULL << VIRTIO_NET_F_MRG_RXBUF |
+		1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
+
+	(void)vdev;
+
+	vmsg_set_reply_u64(msg, features);
+
+	debug("Sending back to guest u64: 0x%016"PRIx64, msg->payload.u64);
+
+	return true;
+}
+
+/**
+ * vu_set_enable_all_rings() - Enable/disable all the virtqueues
+ * @vdev:	vhost-user device
+ * @enable:	New virtqueues state
+ */
+static void vu_set_enable_all_rings(struct vu_dev *vdev, bool enable)
+{
+	uint16_t i;
+
+	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++)
+		vdev->vq[i].enable = enable;
+}
+
+/**
+ * vu_set_features_exec() - Enable features of the back-end
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_features_exec(struct vu_dev *vdev,
+				 struct vhost_user_msg *msg)
+{
+	debug("u64: 0x%016"PRIx64, msg->payload.u64);
+
+	vdev->features = msg->payload.u64;
+	/* We only support devices conforming to VIRTIO 1.0 or
+	 * later
+	 */
+	if (!vu_has_feature(vdev, VIRTIO_F_VERSION_1))
+		die("virtio legacy devices aren't supported by passt");
+
+	if (!vu_has_feature(vdev, VHOST_USER_F_PROTOCOL_FEATURES))
+		vu_set_enable_all_rings(vdev, true);
+
+	return false;
+}
+
+/**
+ * vu_set_owner_exec() - Session start flag, do nothing in our case
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_owner_exec(struct vu_dev *vdev,
+			      struct vhost_user_msg *msg)
+{
+	(void)vdev;
+	(void)msg;
+
+	return false;
+}
+
+/**
+ * map_ring() - Convert ring front-end (QEMU) addresses to our process
+ * 		virtual address space.
+ * @vdev:	vhost-user device
+ * @vq:		Virtqueue
+ *
+ * Return: True if ring cannot be mapped to our address space
+ */
+static bool map_ring(struct vu_dev *vdev, struct vu_virtq *vq)
+{
+	vq->vring.desc = qva_to_va(vdev, vq->vra.desc_user_addr);
+	vq->vring.used = qva_to_va(vdev, vq->vra.used_user_addr);
+	vq->vring.avail = qva_to_va(vdev, vq->vra.avail_user_addr);
+
+	debug("Setting virtq addresses:");
+	debug("    vring_desc  at %p", (void *)vq->vring.desc);
+	debug("    vring_used  at %p", (void *)vq->vring.used);
+	debug("    vring_avail at %p", (void *)vq->vring.avail);
+
+	return !(vq->vring.desc && vq->vring.used && vq->vring.avail);
+}
+
+/**
+ * vu_set_mem_table_exec() - Sets the memory map regions to be able to
+ * 			     translate the vring addresses.
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ *
+ * #syscalls:vu mmap munmap
+ */
+static bool vu_set_mem_table_exec(struct vu_dev *vdev,
+				  struct vhost_user_msg *msg)
+{
+	struct vhost_user_memory m = msg->payload.memory, *memory = &m;
+	unsigned int i;
+
+	for (i = 0; i < vdev->nregions; i++) {
+		const struct vu_dev_region *r = &vdev->regions[i];
+
+		if (r->mmap_addr) {
+			/* NOLINTNEXTLINE(performance-no-int-to-ptr) */
+			munmap((void *)r->mmap_addr, r->size + r->mmap_offset);
+		}
+	}
+	vdev->nregions = memory->nregions;
+
+	debug("vhost-user nregions: %u", memory->nregions);
+	for (i = 0; i < vdev->nregions; i++) {
+		struct vhost_user_memory_region *msg_region = &memory->regions[i];
+		struct vu_dev_region *dev_region = &vdev->regions[i];
+		void *mmap_addr;
+
+		debug("vhost-user region %d", i);
+		debug("    guest_phys_addr: 0x%016"PRIx64,
+		      msg_region->guest_phys_addr);
+		debug("    memory_size:     0x%016"PRIx64,
+		      msg_region->memory_size);
+		debug("    userspace_addr   0x%016"PRIx64,
+		      msg_region->userspace_addr);
+		debug("    mmap_offset      0x%016"PRIx64,
+		      msg_region->mmap_offset);
+
+		dev_region->gpa = msg_region->guest_phys_addr;
+		dev_region->size = msg_region->memory_size;
+		dev_region->qva = msg_region->userspace_addr;
+		dev_region->mmap_offset = msg_region->mmap_offset;
+
+		/* We don't use offset argument of mmap() since the
+		 * mapped address has to be page aligned.
+		 */
+		mmap_addr = mmap(0, dev_region->size + dev_region->mmap_offset,
+				 PROT_READ | PROT_WRITE, MAP_SHARED |
+				 MAP_NORESERVE, msg->fds[i], 0);
+
+		if (mmap_addr == MAP_FAILED)
+			die_perror("vhost-user region mmap error");
+
+		dev_region->mmap_addr = (uint64_t)(uintptr_t)mmap_addr;
+		debug("    mmap_addr:       0x%016"PRIx64,
+		      dev_region->mmap_addr);
+
+		close(msg->fds[i]);
+	}
+
+	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++) {
+		if (vdev->vq[i].vring.desc) {
+			if (map_ring(vdev, &vdev->vq[i]))
+				die("remapping queue %d during setmemtable", i);
+		}
+	}
+
+	return false;
+}
+
+/**
+ * vu_set_vring_num_exec() - Set the size of the queue (vring size)
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_vring_num_exec(struct vu_dev *vdev,
+				  struct vhost_user_msg *msg)
+{
+	unsigned int idx = msg->payload.state.index;
+	unsigned int num = msg->payload.state.num;
+
+	debug("State.index: %u", idx);
+	debug("State.num:   %u", num);
+	vdev->vq[idx].vring.num = num;
+
+	return false;
+}
+
+/**
+ * vu_set_vring_addr_exec() - Set the addresses of the vring
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_vring_addr_exec(struct vu_dev *vdev,
+				   struct vhost_user_msg *msg)
+{
+	/* We need to copy the payload to vhost_vring_addr structure
+         * to access index because address of msg->payload.addr
+         * can be unaligned as it is packed.
+         */
+	struct vhost_vring_addr addr = msg->payload.addr;
+	struct vu_virtq *vq = &vdev->vq[addr.index];
+
+	debug("vhost_vring_addr:");
+	debug("    index:  %d", addr.index);
+	debug("    flags:  %d", addr.flags);
+	debug("    desc_user_addr:   0x%016" PRIx64,
+	      (uint64_t)addr.desc_user_addr);
+	debug("    used_user_addr:   0x%016" PRIx64,
+	      (uint64_t)addr.used_user_addr);
+	debug("    avail_user_addr:  0x%016" PRIx64,
+	      (uint64_t)addr.avail_user_addr);
+	debug("    log_guest_addr:   0x%016" PRIx64,
+	      (uint64_t)addr.log_guest_addr);
+
+	vq->vra = msg->payload.addr;
+	vq->vring.flags = addr.flags;
+	vq->vring.log_guest_addr = addr.log_guest_addr;
+
+	if (map_ring(vdev, vq))
+		die("Invalid vring_addr message");
+
+	vq->used_idx = le16toh(vq->vring.used->idx);
+
+	if (vq->last_avail_idx != vq->used_idx) {
+		debug("Last avail index != used index: %u != %u",
+		      vq->last_avail_idx, vq->used_idx);
+	}
+
+	return false;
+}
+/**
+ * vu_set_vring_base_exec() - Sets the next index to use for descriptors
+ * 			      in this vring
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_vring_base_exec(struct vu_dev *vdev,
+				   struct vhost_user_msg *msg)
+{
+	unsigned int idx = msg->payload.state.index;
+	unsigned int num = msg->payload.state.num;
+
+	debug("State.index: %u", idx);
+	debug("State.num:   %u", num);
+	vdev->vq[idx].shadow_avail_idx = vdev->vq[idx].last_avail_idx = num;
+
+	return false;
+}
+
+/**
+ * vu_get_vring_base_exec() - Stops the vring and returns the current
+ * 			      descriptor index or indices
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: True as a reply is requested
+ */
+static bool vu_get_vring_base_exec(struct vu_dev *vdev,
+				   struct vhost_user_msg *msg)
+{
+	unsigned int idx = msg->payload.state.index;
+
+	debug("State.index: %u", idx);
+	msg->payload.state.num = vdev->vq[idx].last_avail_idx;
+	msg->hdr.size = sizeof(msg->payload.state);
+
+	vdev->vq[idx].started = false;
+
+	if (vdev->vq[idx].call_fd != -1) {
+		close(vdev->vq[idx].call_fd);
+		vdev->vq[idx].call_fd = -1;
+	}
+	if (vdev->vq[idx].kick_fd != -1) {
+		vu_remove_watch(vdev, vdev->vq[idx].kick_fd);
+		close(vdev->vq[idx].kick_fd);
+		vdev->vq[idx].kick_fd = -1;
+	}
+
+	return true;
+}
+
+/**
+ * vu_set_watch() - Add a file descriptor to the passt epoll file descriptor
+ * @vdev:	vhost-user device
+ * @idx:	queue index of the file descriptor to add
+ */
+static void vu_set_watch(const struct vu_dev *vdev, int idx)
+{
+	/* Placeholder to add passt related code */
+	(void)vdev;
+	(void)idx;
+}
+
+/**
+ * vu_check_queue_msg_file() - Check if a message is valid,
+ * 			       close fds if NOFD bit is set
+ * @vmsg:	vhost-user message
+ */
+static void vu_check_queue_msg_file(struct vhost_user_msg *msg)
+{
+	bool nofd = msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK;
+	int idx = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+
+	if (idx >= VHOST_USER_MAX_QUEUES)
+		die("Invalid vhost-user queue index: %u", idx);
+
+	if (nofd) {
+		vmsg_close_fds(msg);
+		return;
+	}
+
+	if (msg->fd_num != 1)
+		die("Invalid fds in vhost-user request: %d", msg->hdr.request);
+}
+
+/**
+ * vu_set_vring_kick_exec() - Set the event file descriptor for adding buffers
+ * 			      to the vring
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_vring_kick_exec(struct vu_dev *vdev,
+				   struct vhost_user_msg *msg)
+{
+	bool nofd = msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK;
+	int idx = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+
+	debug("u64: 0x%016"PRIx64, msg->payload.u64);
+
+	vu_check_queue_msg_file(msg);
+
+	if (vdev->vq[idx].kick_fd != -1) {
+		vu_remove_watch(vdev, vdev->vq[idx].kick_fd);
+		close(vdev->vq[idx].kick_fd);
+		vdev->vq[idx].kick_fd = -1;
+	}
+
+	if (!nofd)
+		vdev->vq[idx].kick_fd = msg->fds[0];
+
+	debug("Got kick_fd: %d for vq: %d", vdev->vq[idx].kick_fd, idx);
+
+	vdev->vq[idx].started = true;
+
+	if (vdev->vq[idx].kick_fd != -1 && VHOST_USER_IS_QUEUE_TX(idx)) {
+		vu_set_watch(vdev, idx);
+		debug("Waiting for kicks on fd: %d for vq: %d",
+		      vdev->vq[idx].kick_fd, idx);
+	}
+
+	return false;
+}
+
+/**
+ * vu_set_vring_call_exec() - Set the event file descriptor to signal when
+ * 			      buffers are used
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_vring_call_exec(struct vu_dev *vdev,
+				   struct vhost_user_msg *msg)
+{
+	bool nofd = msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK;
+	int idx = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+
+	debug("u64: 0x%016"PRIx64, msg->payload.u64);
+
+	vu_check_queue_msg_file(msg);
+
+	if (vdev->vq[idx].call_fd != -1) {
+		close(vdev->vq[idx].call_fd);
+		vdev->vq[idx].call_fd = -1;
+	}
+
+	if (!nofd)
+		vdev->vq[idx].call_fd = msg->fds[0];
+
+	/* in case of I/O hang after reconnecting */
+	if (vdev->vq[idx].call_fd != -1)
+		eventfd_write(msg->fds[0], 1);
+
+	debug("Got call_fd: %d for vq: %d", vdev->vq[idx].call_fd, idx);
+
+	return false;
+}
+
+/**
+ * vu_set_vring_err_exec() - Set the event file descriptor to signal when
+ * 			     error occurs
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_vring_err_exec(struct vu_dev *vdev,
+				  struct vhost_user_msg *msg)
+{
+	bool nofd = msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK;
+	int idx = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+
+	debug("u64: 0x%016"PRIx64, msg->payload.u64);
+
+	vu_check_queue_msg_file(msg);
+
+	if (vdev->vq[idx].err_fd != -1) {
+		close(vdev->vq[idx].err_fd);
+		vdev->vq[idx].err_fd = -1;
+	}
+
+	if (!nofd)
+		vdev->vq[idx].err_fd = msg->fds[0];
+
+	return false;
+}
+
+/**
+ * vu_get_protocol_features_exec() - Provide the protocol (vhost-user) features
+ * 				     to the front-end
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: True as a reply is requested
+ */
+static bool vu_get_protocol_features_exec(struct vu_dev *vdev,
+					  struct vhost_user_msg *msg)
+{
+	uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_REPLY_ACK;
+
+	(void)vdev;
+	vmsg_set_reply_u64(msg, features);
+
+	return true;
+}
+
+/**
+ * vu_set_protocol_features_exec() - Enable protocol (vhost-user) features
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_protocol_features_exec(struct vu_dev *vdev,
+					  struct vhost_user_msg *msg)
+{
+	uint64_t features = msg->payload.u64;
+
+	debug("u64: 0x%016"PRIx64, features);
+
+	vdev->protocol_features = msg->payload.u64;
+
+	return false;
+}
+
+/**
+ * vu_get_queue_num_exec() - Tell how many queues we support
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: True as a reply is requested
+ */
+static bool vu_get_queue_num_exec(struct vu_dev *vdev,
+				  struct vhost_user_msg *msg)
+{
+	(void)vdev;
+
+	vmsg_set_reply_u64(msg, VHOST_USER_MAX_QUEUES);
+
+	return true;
+}
+
+/**
+ * vu_set_vring_enable_exec() - Enable or disable corresponding vring
+ * @vdev:	vhost-user device
+ * @vmsg:	vhost-user message
+ *
+ * Return: False as no reply is requested
+ */
+static bool vu_set_vring_enable_exec(struct vu_dev *vdev,
+				     struct vhost_user_msg *msg)
+{
+	unsigned int enable = msg->payload.state.num;
+	unsigned int idx = msg->payload.state.index;
+
+	debug("State.index:  %u", idx);
+	debug("State.enable: %u", enable);
+
+	if (idx >= VHOST_USER_MAX_QUEUES)
+		die("Invalid vring_enable index: %u", idx);
+
+	vdev->vq[idx].enable = enable;
+	return false;
+}
+
+/**
+ * vu_init() - Initialize vhost-user device structure
+ * @c:		execution context
+ * @vdev:	vhost-user device
+ */
+/* cppcheck-suppress unusedFunction */
+void vu_init(struct ctx *c, struct vu_dev *vdev)
+{
+	int i;
+
+	vdev->context = c;
+	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++) {
+		vdev->vq[i] = (struct vu_virtq){
+			.call_fd = -1,
+			.kick_fd = -1,
+			.err_fd = -1,
+			.notification = true,
+		};
+	}
+}
+
+/**
+ * vu_cleanup() - Reset vhost-user device
+ * @vdev:	vhost-user device
+ */
+/* cppcheck-suppress unusedFunction */
+void vu_cleanup(struct vu_dev *vdev)
+{
+	unsigned int i;
+
+	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++) {
+		struct vu_virtq *vq = &vdev->vq[i];
+
+		vq->started = false;
+		vq->notification = true;
+
+		if (vq->call_fd != -1) {
+			close(vq->call_fd);
+			vq->call_fd = -1;
+		}
+		if (vq->err_fd != -1) {
+			close(vq->err_fd);
+			vq->err_fd = -1;
+		}
+		if (vq->kick_fd != -1) {
+			vu_remove_watch(vdev, vq->kick_fd);
+			close(vq->kick_fd);
+			vq->kick_fd = -1;
+		}
+
+		vq->vring.desc = 0;
+		vq->vring.used = 0;
+		vq->vring.avail = 0;
+	}
+
+	for (i = 0; i < vdev->nregions; i++) {
+		const struct vu_dev_region *r = &vdev->regions[i];
+
+		if (r->mmap_addr) {
+			/* NOLINTNEXTLINE(performance-no-int-to-ptr) */
+			munmap((void *)r->mmap_addr, r->size + r->mmap_offset);
+		}
+	}
+	vdev->nregions = 0;
+}
+
+/**
+ * vu_sock_reset() - Reset connection socket
+ * @vdev:	vhost-user device
+ */
+static void vu_sock_reset(struct vu_dev *vdev)
+{
+	/* Placeholder to add passt related code */
+	(void)vdev;
+}
+
+static bool (*vu_handle[VHOST_USER_MAX])(struct vu_dev *vdev,
+					struct vhost_user_msg *msg) = {
+	[VHOST_USER_GET_FEATURES]	   = vu_get_features_exec,
+	[VHOST_USER_SET_FEATURES]	   = vu_set_features_exec,
+	[VHOST_USER_GET_PROTOCOL_FEATURES] = vu_get_protocol_features_exec,
+	[VHOST_USER_SET_PROTOCOL_FEATURES] = vu_set_protocol_features_exec,
+	[VHOST_USER_GET_QUEUE_NUM]	   = vu_get_queue_num_exec,
+	[VHOST_USER_SET_OWNER]		   = vu_set_owner_exec,
+	[VHOST_USER_SET_MEM_TABLE]	   = vu_set_mem_table_exec,
+	[VHOST_USER_SET_VRING_NUM]	   = vu_set_vring_num_exec,
+	[VHOST_USER_SET_VRING_ADDR]	   = vu_set_vring_addr_exec,
+	[VHOST_USER_SET_VRING_BASE]	   = vu_set_vring_base_exec,
+	[VHOST_USER_GET_VRING_BASE]	   = vu_get_vring_base_exec,
+	[VHOST_USER_SET_VRING_KICK]	   = vu_set_vring_kick_exec,
+	[VHOST_USER_SET_VRING_CALL]	   = vu_set_vring_call_exec,
+	[VHOST_USER_SET_VRING_ERR]	   = vu_set_vring_err_exec,
+	[VHOST_USER_SET_VRING_ENABLE]	   = vu_set_vring_enable_exec,
+};
+
+/**
+ * vu_control_handler() - Handle control commands for vhost-user
+ * @vdev:	vhost-user device
+ * @fd:		vhost-user message socket
+ * @events:	epoll events
+ */
+/* cppcheck-suppress unusedFunction */
+void vu_control_handler(struct vu_dev *vdev, int fd, uint32_t events)
+{
+	struct vhost_user_msg msg = { 0 };
+	bool need_reply, reply_requested;
+	int ret;
+
+	if (events & (EPOLLRDHUP | EPOLLHUP | EPOLLERR)) {
+		vu_sock_reset(vdev);
+		return;
+	}
+
+	ret = vu_message_read_default(fd, &msg);
+	if (ret == 0) {
+		vu_sock_reset(vdev);
+		return;
+	}
+	debug("================ Vhost user message ================");
+	debug("Request: %s (%d)", vu_request_to_string(msg.hdr.request),
+		msg.hdr.request);
+	debug("Flags:   0x%x", msg.hdr.flags);
+	debug("Size:    %u", msg.hdr.size);
+
+	need_reply = msg.hdr.flags & VHOST_USER_NEED_REPLY_MASK;
+
+	if (msg.hdr.request >= 0 && msg.hdr.request < VHOST_USER_MAX &&
+	    vu_handle[msg.hdr.request])
+		reply_requested = vu_handle[msg.hdr.request](vdev, &msg);
+	else
+		die("Unhandled request: %d", msg.hdr.request);
+
+	/* cppcheck-suppress legacyUninitvar */
+	if (!reply_requested && need_reply) {
+		msg.payload.u64 = 0;
+		msg.hdr.flags = 0;
+		msg.hdr.size = sizeof(msg.payload.u64);
+		msg.fd_num = 0;
+		reply_requested = true;
+	}
+
+	if (reply_requested)
+		vu_send_reply(fd, &msg);
+}
diff --git a/vhost_user.h b/vhost_user.h
new file mode 100644
index 000000000000..5af349ba58b8
--- /dev/null
+++ b/vhost_user.h
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * vhost-user API, command management and virtio interface
+ *
+ * Copyright Red Hat
+ * Author: Laurent Vivier &lt;lvivier(a)redhat.com&gt;
+ */
+
+/* some parts from subprojects/libvhost-user/libvhost-user.h */
+
+#ifndef VHOST_USER_H
+#define VHOST_USER_H
+
+#include "virtio.h"
+#include "iov.h"
+
+#define VHOST_USER_F_PROTOCOL_FEATURES 30
+
+#define VHOST_MEMORY_BASELINE_NREGIONS 8
+
+/**
+ * enum vhost_user_protocol_feature - List of available vhost-user features
+ */
+enum vhost_user_protocol_feature {
+	VHOST_USER_PROTOCOL_F_MQ = 0,
+	VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
+	VHOST_USER_PROTOCOL_F_RARP = 2,
+	VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
+	VHOST_USER_PROTOCOL_F_NET_MTU = 4,
+	VHOST_USER_PROTOCOL_F_BACKEND_REQ = 5,
+	VHOST_USER_PROTOCOL_F_CROSS_ENDIAN = 6,
+	VHOST_USER_PROTOCOL_F_CRYPTO_SESSION = 7,
+	VHOST_USER_PROTOCOL_F_PAGEFAULT = 8,
+	VHOST_USER_PROTOCOL_F_CONFIG = 9,
+	VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10,
+	VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11,
+	VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12,
+	VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
+	VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,
+
+	VHOST_USER_PROTOCOL_F_MAX
+};
+
+/**
+ * enum vhost_user_request - List of available vhost-user requests
+ */
+enum vhost_user_request {
+	VHOST_USER_NONE = 0,
+	VHOST_USER_GET_FEATURES = 1,
+	VHOST_USER_SET_FEATURES = 2,
+	VHOST_USER_SET_OWNER = 3,
+	VHOST_USER_RESET_OWNER = 4,
+	VHOST_USER_SET_MEM_TABLE = 5,
+	VHOST_USER_SET_LOG_BASE = 6,
+	VHOST_USER_SET_LOG_FD = 7,
+	VHOST_USER_SET_VRING_NUM = 8,
+	VHOST_USER_SET_VRING_ADDR = 9,
+	VHOST_USER_SET_VRING_BASE = 10,
+	VHOST_USER_GET_VRING_BASE = 11,
+	VHOST_USER_SET_VRING_KICK = 12,
+	VHOST_USER_SET_VRING_CALL = 13,
+	VHOST_USER_SET_VRING_ERR = 14,
+	VHOST_USER_GET_PROTOCOL_FEATURES = 15,
+	VHOST_USER_SET_PROTOCOL_FEATURES = 16,
+	VHOST_USER_GET_QUEUE_NUM = 17,
+	VHOST_USER_SET_VRING_ENABLE = 18,
+	VHOST_USER_SEND_RARP = 19,
+	VHOST_USER_NET_SET_MTU = 20,
+	VHOST_USER_SET_BACKEND_REQ_FD = 21,
+	VHOST_USER_IOTLB_MSG = 22,
+	VHOST_USER_SET_VRING_ENDIAN = 23,
+	VHOST_USER_GET_CONFIG = 24,
+	VHOST_USER_SET_CONFIG = 25,
+	VHOST_USER_CREATE_CRYPTO_SESSION = 26,
+	VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
+	VHOST_USER_POSTCOPY_ADVISE  = 28,
+	VHOST_USER_POSTCOPY_LISTEN  = 29,
+	VHOST_USER_POSTCOPY_END     = 30,
+	VHOST_USER_GET_INFLIGHT_FD = 31,
+	VHOST_USER_SET_INFLIGHT_FD = 32,
+	VHOST_USER_GPU_SET_SOCKET = 33,
+	VHOST_USER_VRING_KICK = 35,
+	VHOST_USER_GET_MAX_MEM_SLOTS = 36,
+	VHOST_USER_ADD_MEM_REG = 37,
+	VHOST_USER_REM_MEM_REG = 38,
+	VHOST_USER_MAX
+};
+
+/**
+ * struct vhost_user_header - vhost-user message header
+ * @request:	Request type of the message
+ * @flags:	Request flags
+ * @size:	The following payload size
+ */
+struct vhost_user_header {
+	enum vhost_user_request request;
+
+#define VHOST_USER_VERSION_MASK     0x3
+#define VHOST_USER_REPLY_MASK       (0x1 << 2)
+#define VHOST_USER_NEED_REPLY_MASK  (0x1 << 3)
+	uint32_t flags;
+	uint32_t size;
+} __attribute__ ((__packed__));
+
+/**
+ * struct vhost_user_memory_region - Front-end shared memory region information
+ * @guest_phys_addr:	Guest physical address of the region
+ * @memory_size:	Memory size
+ * @userspace_addr:	front-end (QEMU) userspace address
+ * @mmap_offset:	region offset in the shared memory area
+ */
+struct vhost_user_memory_region {
+	uint64_t guest_phys_addr;
+	uint64_t memory_size;
+	uint64_t userspace_addr;
+	uint64_t mmap_offset;
+};
+
+/**
+ * struct vhost_user_memory - List of all the shared memory regions
+ * @nregions:	Number of memory regions
+ * @padding:	Padding
+ * @regions:	Memory regions list
+ */
+struct vhost_user_memory {
+	uint32_t nregions;
+	uint32_t padding;
+	struct vhost_user_memory_region regions[VHOST_MEMORY_BASELINE_NREGIONS];
+};
+
+/**
+ * union vhost_user_payload - vhost-user message payload
+ * @u64:		64-bit payload
+ * @state:		vring state payload
+ * @addr:		vring addresses payload
+ * vhost_user_memory:	Memory regions information payload
+ */
+union vhost_user_payload {
+#define VHOST_USER_VRING_IDX_MASK   0xff
+#define VHOST_USER_VRING_NOFD_MASK  (0x1 << 8)
+	uint64_t u64;
+	struct vhost_vring_state state;
+	struct vhost_vring_addr addr;
+	struct vhost_user_memory memory;
+};
+
+/**
+ * struct vhost_user_msg - vhost-use message
+ * @hdr:		Message header
+ * @payload:		Message payload
+ * @fds:		File descriptors associated with the message
+ * 			in the ancillary data.
+ * 			(shared memory or event file descriptors)
+ * @fd_num:		Number of file descriptors
+ */
+struct vhost_user_msg {
+	struct vhost_user_header hdr;
+	union vhost_user_payload payload;
+
+	int fds[VHOST_MEMORY_BASELINE_NREGIONS];
+	int fd_num;
+} __attribute__ ((__packed__));
+#define VHOST_USER_HDR_SIZE sizeof(struct vhost_user_header)
+
+/* index of the RX virtqueue */
+#define VHOST_USER_RX_QUEUE 0
+/* index of the TX virtqueue */
+#define VHOST_USER_TX_QUEUE 1
+
+/* in case of multiqueue, the RX and TX queues are interleaved */
+#define VHOST_USER_IS_QUEUE_TX(n)	(n % 2)
+#define VHOST_USER_IS_QUEUE_RX(n)	(!(n % 2))
+
+/* Default virtio-net header for passt */
+#define VU_HEADER ((struct virtio_net_hdr){	\
+	.flags = VIRTIO_NET_HDR_F_DATA_VALID,	\
+	.gso_type = VIRTIO_NET_HDR_GSO_NONE,	\
+})
+
+/**
+ * vu_queue_enabled - Return state of a virtqueue
+ * @vq:		virtqueue to check
+ *
+ * Return: true if the virqueue is enabled, false otherwise
+ */
+/* cppcheck-suppress unusedFunction */
+static inline bool vu_queue_enabled(const struct vu_virtq *vq)
+{
+	return vq->enable;
+}
+
+/**
+ * vu_queue_started - Return state of a virtqueue
+ * @vq:		virtqueue to check
+ *
+ * Return: true if the virqueue is started, false otherwise
+ */
+/* cppcheck-suppress unusedFunction */
+static inline bool vu_queue_started(const struct vu_virtq *vq)
+{
+	return vq->started;
+}
+
+void vu_print_capabilities(void);
+void vu_init(struct ctx *c, struct vu_dev *vdev);
+void vu_cleanup(struct vu_dev *vdev);
+void vu_control_handler(struct vu_dev *vdev, int fd, uint32_t events);
+#endif /* VHOST_USER_H */
diff --git a/virtio.h b/virtio.h
index 94efeb049fbc..6410d60f9b3f 100644
--- a/virtio.h
+++ b/virtio.h
@@ -105,6 +105,7 @@ struct vu_dev_region {
  * @protocol_features:	Vhost-user protocol features
  */
 struct vu_dev {
+	struct ctx *context;
 	uint32_t nregions;
 	struct vu_dev_region regions[VHOST_USER_MAX_RAM_SLOTS];
 	struct vu_virtq vq[VHOST_USER_MAX_QUEUES];
-- 
2.47.0

Export tcp_fill_headers[4|6]() and tcp_update_check_tcp[4|6]().

They'll be needed by vhost-user.

Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>
---
 tcp.c          | 30 +++++++++++++++---------------
 tcp_internal.h | 15 +++++++++++++++
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/tcp.c b/tcp.c
index 6a98dfaed59b..5d9968847d20 100644
--- a/tcp.c
+++ b/tcp.c
@@ -758,9 +758,9 @@ static void tcp_sock_set_bufsize(const struct ctx *c, int s)
  * @iov_cnt:	Length of the array
  * @l4offset:	IPv4 payload offset in the iovec array
  */
-static void tcp_update_check_tcp4(const struct iphdr *iph,
-				  const struct iovec *iov, int iov_cnt,
-				  size_t l4offset)
+void tcp_update_check_tcp4(const struct iphdr *iph,
+			   const struct iovec *iov, int iov_cnt,
+			   size_t l4offset)
 {
 	uint16_t l4len = ntohs(iph->tot_len) - sizeof(struct iphdr);
 	struct in_addr saddr = { .s_addr = iph->saddr };
@@ -810,9 +810,9 @@ static void tcp_update_check_tcp4(const struct iphdr *iph,
  * @iov_cnt:	Length of the array
  * @l4offset:	IPv6 payload offset in the iovec array
  */
-static void tcp_update_check_tcp6(const struct ipv6hdr *ip6h,
-				  const struct iovec *iov, int iov_cnt,
-				  size_t l4offset)
+void tcp_update_check_tcp6(const struct ipv6hdr *ip6h,
+			   const struct iovec *iov, int iov_cnt,
+			   size_t l4offset)
 {
 	uint16_t l4len = ntohs(ip6h->payload_len);
 	size_t check_ofs;
@@ -978,11 +978,11 @@ static void tcp_fill_header(struct tcphdr *th,
  *
  * Return: The IPv4 payload length, host order
  */
-static size_t tcp_fill_headers4(const struct tcp_tap_conn *conn,
-				struct tap_hdr *taph,
-				struct iphdr *iph, struct tcp_payload_t *bp,
-				size_t dlen, const uint16_t *check,
-				uint32_t seq, bool no_tcp_csum)
+size_t tcp_fill_headers4(const struct tcp_tap_conn *conn,
+			 struct tap_hdr *taph,
+			 struct iphdr *iph, struct tcp_payload_t *bp,
+			 size_t dlen, const uint16_t *check,
+			 uint32_t seq, bool no_tcp_csum)
 {
 	const struct flowside *tapside = TAPFLOW(conn);
 	const struct in_addr *src4 = inany_v4(&tapside->oaddr);
@@ -1030,10 +1030,10 @@ static size_t tcp_fill_headers4(const struct tcp_tap_conn *conn,
  *
  * Return: The IPv6 payload length, host order
  */
-static size_t tcp_fill_headers6(const struct tcp_tap_conn *conn,
-				struct tap_hdr *taph,
-				struct ipv6hdr *ip6h, struct tcp_payload_t *bp,
-				size_t dlen, uint32_t seq, bool no_tcp_csum)
+size_t tcp_fill_headers6(const struct tcp_tap_conn *conn,
+			 struct tap_hdr *taph,
+			 struct ipv6hdr *ip6h, struct tcp_payload_t *bp,
+			 size_t dlen, uint32_t seq, bool no_tcp_csum)
 {
 	const struct flowside *tapside = TAPFLOW(conn);
 	size_t l4len = dlen + sizeof(bp->th);
diff --git a/tcp_internal.h b/tcp_internal.h
index c846f605834c..8625eed894d5 100644
--- a/tcp_internal.h
+++ b/tcp_internal.h
@@ -162,6 +162,21 @@ void tcp_rst_do(const struct ctx *c, struct tcp_tap_conn *conn);
 
 struct tcp_info_linux;
 
+void tcp_update_check_tcp4(const struct iphdr *iph,
+			   const struct iovec *iov, int iov_cnt,
+			   size_t l4offset);
+void tcp_update_check_tcp6(const struct ipv6hdr *ip6h,
+			   const struct iovec *iov, int iov_cnt,
+			   size_t l4offset);
+size_t tcp_fill_headers4(const struct tcp_tap_conn *conn,
+			 struct tap_hdr *taph,
+			 struct iphdr *iph, struct tcp_payload_t *bp,
+			 size_t dlen, const uint16_t *check,
+			 uint32_t seq, bool no_tcp_csum);
+size_t tcp_fill_headers6(const struct tcp_tap_conn *conn,
+			 struct tap_hdr *taph,
+			 struct ipv6hdr *ip6h, struct tcp_payload_t *bp,
+			 size_t dlen, uint32_t seq, bool no_tcp_csum);
 size_t tcp_l2_buf_fill_headers(const struct tcp_tap_conn *conn,
 			       struct iovec *iov, size_t dlen,
 			       const uint16_t *check, uint32_t seq,
-- 
2.47.0

add virtio and vhost-user functions to connect with QEMU.

  $ ./passt --vhost-user

and

  # qemu-system-x86_64 ... -m 4G \
        -object memory-backend-memfd,id=memfd0,share=on,size=4G \
        -numa node,memdev=memfd0 \
        -chardev socket,id=chr0,path=/tmp/passt_1.socket \
        -netdev vhost-user,id=netdev0,chardev=chr0 \
        -device virtio-net,mac=9a:2b:2c:2d:2e:2f,netdev=netdev0 \
        ...

Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
---
 Makefile     |   6 +-
 conf.c       |  19 +-
 epoll_type.h |   4 +
 iov.c        |   1 -
 isolation.c  |  17 +-
 packet.c     |  11 ++
 packet.h     |   8 +-
 passt.1      |  10 +-
 passt.c      |   9 +
 passt.h      |   7 +
 pcap.c       |   1 -
 tap.c        |  77 ++++++--
 tap.h        |   5 +-
 tcp.c        |   7 +
 tcp_vu.c     | 497 +++++++++++++++++++++++++++++++++++++++++++++++++++
 tcp_vu.h     |  12 ++
 udp.c        |  11 ++
 udp_vu.c     | 343 +++++++++++++++++++++++++++++++++++
 udp_vu.h     |  13 ++
 vhost_user.c |  41 +++--
 vhost_user.h |   4 +-
 virtio.c     |   5 -
 vu_common.c  | 282 +++++++++++++++++++++++++++++
 vu_common.h  |  60 +++++++
 24 files changed, 1397 insertions(+), 53 deletions(-)
 create mode 100644 tcp_vu.c
 create mode 100644 tcp_vu.h
 create mode 100644 udp_vu.c
 create mode 100644 udp_vu.h
 create mode 100644 vu_common.c
 create mode 100644 vu_common.h

diff --git a/Makefile b/Makefile
index bcb084e66e4d..faa5c23346ac 100644
--- a/Makefile
+++ b/Makefile
@@ -37,7 +37,8 @@ FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
 PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c flow.c fwd.c \
 	icmp.c igmp.c inany.c iov.c ip.c isolation.c lineread.c log.c mld.c \
 	ndp.c netlink.c packet.c passt.c pasta.c pcap.c pif.c tap.c tcp.c \
-	tcp_buf.c tcp_splice.c udp.c udp_flow.c util.c vhost_user.c virtio.c
+	tcp_buf.c tcp_splice.c tcp_vu.c udp.c udp_flow.c udp_vu.c util.c \
+	vhost_user.c virtio.c vu_common.c
 QRAP_SRCS = qrap.c
 SRCS = $(PASST_SRCS) $(QRAP_SRCS)
 
@@ -47,7 +48,8 @@ PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h flow.h
fwd.h \
 	flow_table.h icmp.h icmp_flow.h inany.h iov.h ip.h isolation.h \
 	lineread.h log.h ndp.h netlink.h packet.h passt.h pasta.h pcap.h pif.h \
 	siphash.h tap.h tcp.h tcp_buf.h tcp_conn.h tcp_internal.h tcp_splice.h \
-	udp.h udp_flow.h util.h vhost_user.h virtio.h
+	tcp_vu.h udp.h udp_flow.h udp_internal.h udp_vu.h util.h vhost_user.h \
+	virtio.h vu_common.h
 HEADERS = $(PASST_HEADERS) seccomp.h
 
 C := \#include <sys/random.h>\nint main(){int a=getrandom(0, 0, 0);}
diff --git a/conf.c b/conf.c
index 86566dbf1ee0..d9d63d70ae5a 100644
--- a/conf.c
+++ b/conf.c
@@ -45,6 +45,7 @@
 #include "lineread.h"
 #include "isolation.h"
 #include "log.h"
+#include "vhost_user.h"
 
 #define NETNS_RUN_DIR	"/run/netns"
 
@@ -769,9 +770,14 @@ static void usage(const char *name, FILE *f, int status)
 			"    default: same interface name as external one\n");
 	} else {
 		FPRINTF(f,
-			"  -s, --socket PATH	UNIX domain socket path\n"
+			"  -s, --socket, --socket-path PATH	UNIX domain socket path\n"
 			"    default: probe free path starting from "
 			UNIX_SOCK_PATH "\n", 1);
+		FPRINTF(f,
+			"  --vhost-user		Enable vhost-user mode\n"
+			"    UNIX domain socket is provided by -s option\n"
+			"  --print-capabilities	print back-end capabilities in JSON format,\n"
+			"    only meaningful for vhost-user mode\n");
 	}
 
 	FPRINTF(f,
@@ -1305,6 +1311,10 @@ void conf(struct ctx *c, int argc, char **argv)
 		{"map-guest-addr", required_argument,	NULL,		22 },
 		{"host-lo-to-ns-lo", no_argument, 	NULL,		23 },
 		{"dns-host",	required_argument,	NULL,		24 },
+		{"vhost-user",	no_argument,		NULL,		25 },
+		/* vhost-user backend program convention */
+		{"print-capabilities", no_argument,	NULL,		26 },
+		{"socket-path",	required_argument,	NULL,		's' },
 		{ 0 },
 	};
 	const char *logname = (c->mode == MODE_PASTA) ? "pasta" :
"passt";
@@ -1498,6 +1508,13 @@ void conf(struct ctx *c, int argc, char **argv)
 				break;
 
 			die("Invalid host nameserver address: %s", optarg);
+		case 25:
+			if (c->mode == MODE_PASTA)
+				die("--vhost-user is for passt mode only");
+			c->mode = MODE_VU;
+			break;
+		case 26:
+			vu_print_capabilities();
 			break;
 		case 'd':
 			c->debug = 1;
diff --git a/epoll_type.h b/epoll_type.h
index 0ad1efa0ccec..f3ef41584757 100644
--- a/epoll_type.h
+++ b/epoll_type.h
@@ -36,6 +36,10 @@ enum epoll_type {
 	EPOLL_TYPE_TAP_PASST,
 	/* socket listening for qemu socket connections */
 	EPOLL_TYPE_TAP_LISTEN,
+	/* vhost-user command socket */
+	EPOLL_TYPE_VHOST_CMD,
+	/* vhost-user kick event socket */
+	EPOLL_TYPE_VHOST_KICK,
 
 	EPOLL_NUM_TYPES,
 };
diff --git a/iov.c b/iov.c
index 3f9e229a305f..3741db21790f 100644
--- a/iov.c
+++ b/iov.c
@@ -68,7 +68,6 @@ size_t iov_skip_bytes(const struct iovec *iov, size_t n,
  *
  * Returns:    The number of bytes successfully copied.
  */
-/* cppcheck-suppress unusedFunction */
 size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,
 		    size_t offset, const void *buf, size_t bytes)
 {
diff --git a/isolation.c b/isolation.c
index 45fba1e68b9d..c944fb35c3a4 100644
--- a/isolation.c
+++ b/isolation.c
@@ -379,12 +379,21 @@ void isolate_postfork(const struct ctx *c)
 
 	prctl(PR_SET_DUMPABLE, 0);
 
-	if (c->mode == MODE_PASTA) {
-		prog.len = (unsigned short)ARRAY_SIZE(filter_pasta);
-		prog.filter = filter_pasta;
-	} else {
+	switch (c->mode) {
+	case MODE_PASST:
 		prog.len = (unsigned short)ARRAY_SIZE(filter_passt);
 		prog.filter = filter_passt;
+		break;
+	case MODE_PASTA:
+		prog.len = (unsigned short)ARRAY_SIZE(filter_pasta);
+		prog.filter = filter_pasta;
+		break;
+	case MODE_VU:
+		prog.len = (unsigned short)ARRAY_SIZE(filter_vu);
+		prog.filter = filter_vu;
+		break;
+	default:
+		ASSERT(0);
 	}
 
 	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) ||
diff --git a/packet.c b/packet.c
index 37489961a37e..e5a78d079231 100644
--- a/packet.c
+++ b/packet.c
@@ -36,6 +36,17 @@
 static int packet_check_range(const struct pool *p, size_t offset, size_t len,
 			      const char *start, const char *func, int line)
 {
+	if (p->buf_size == 0) {
+		int ret;
+
+		ret = vu_packet_check_range((void *)p->buf, offset, len, start);
+
+		if (ret == -1)
+			trace("cannot find region, %s:%i", func, line);
+
+		return ret;
+	}
+
 	if (start < p->buf) {
 		trace("packet start %p before buffer start %p, "
 		      "%s:%i", (void *)start, (void *)p->buf, func, line);
diff --git a/packet.h b/packet.h
index 8377dcf678bb..3f70e949c066 100644
--- a/packet.h
+++ b/packet.h
@@ -8,8 +8,10 @@
 
 /**
  * struct pool - Generic pool of packets stored in a buffer
- * @buf:	Buffer storing packet descriptors
- * @buf_size:	Total size of buffer
+ * @buf:	Buffer storing packet descriptors,
+ * 		a struct vu_dev_region array for passt vhost-user mode
+ * @buf_size:	Total size of buffer,
+ * 		0 for passt vhost-user mode
  * @size:	Number of usable descriptors for the pool
  * @count:	Number of used descriptors for the pool
  * @pkt:	Descriptors: see macros below
@@ -22,6 +24,8 @@ struct pool {
 	struct iovec pkt[1];
 };
 
+int vu_packet_check_range(void *buf, size_t offset, size_t len,
+			  const char *start);
 void packet_add_do(struct pool *p, size_t len, const char *start,
 		   const char *func, int line);
 void *packet_get_do(const struct pool *p, const size_t idx,
diff --git a/passt.1 b/passt.1
index f0849787217e..a100e0f1d727 100644
--- a/passt.1
+++ b/passt.1
@@ -397,12 +397,20 @@ interface address are configured on a given host interface.
 .SS \fBpasst\fR-only options
 
 .TP
-.BR \-s ", " \-\-socket " " \fIpath
+.BR \-s ", " \-\-socket-path ", " \-\-socket " " \fIpath
 Path for UNIX domain socket used by \fBqemu\fR(1) or \fBqrap\fR(1) to connect to
 \fBpasst\fR.
 Default is to probe a free socket, not accepting connections, starting from
 \fI/tmp/passt_1.socket\fR to \fI/tmp/passt_64.socket\fR.
 
+.TP
+.BR \-\-vhost-user
+Enable vhost-user. The vhost-user command socket is provided by \fB--socket\fR.
+
+.TP
+.BR \-\-print-capabilities
+Print back-end capabilities in JSON format, only meaningful for vhost-user mode.
+
 .TP
 .BR \-F ", " \-\-fd " " \fIFD
 Pass a pre-opened, connected socket to \fBpasst\fR. Usually the socket is opened
diff --git a/passt.c b/passt.c
index 25f5c1a1a2fd..eb96a449b29e 100644
--- a/passt.c
+++ b/passt.c
@@ -50,6 +50,7 @@
 #include "log.h"
 #include "tcp_splice.h"
 #include "ndp.h"
+#include "vu_common.h"
 
 #define EPOLL_EVENTS		8
 
@@ -72,6 +73,8 @@ char *epoll_type_str[] = {
 	[EPOLL_TYPE_TAP_PASTA]		= "/dev/net/tun device",
 	[EPOLL_TYPE_TAP_PASST]		= "connected qemu socket",
 	[EPOLL_TYPE_TAP_LISTEN]		= "listening qemu socket",
+	[EPOLL_TYPE_VHOST_CMD]		= "vhost-user command socket",
+	[EPOLL_TYPE_VHOST_KICK]		= "vhost-user kick socket",
 };
 static_assert(ARRAY_SIZE(epoll_type_str) == EPOLL_NUM_TYPES,
 	      "epoll_type_str[] doesn't match enum epoll_type");
@@ -346,6 +349,12 @@ loop:
 		case EPOLL_TYPE_PING:
 			icmp_sock_handler(&c, ref);
 			break;
+		case EPOLL_TYPE_VHOST_CMD:
+			vu_control_handler(c.vdev, c.fd_tap, eventmask);
+			break;
+		case EPOLL_TYPE_VHOST_KICK:
+			vu_kick_cb(c.vdev, ref, &now);
+			break;
 		default:
 			/* Can't happen */
 			ASSERT(0);
diff --git a/passt.h b/passt.h
index 72c7f723a7bb..076f7db43345 100644
--- a/passt.h
+++ b/passt.h
@@ -25,6 +25,7 @@ union epoll_ref;
 #include "fwd.h"
 #include "tcp.h"
 #include "udp.h"
+#include "vhost_user.h"
 
 /* Default address for our end on the tap interface.  Bit 0 of byte 0 must be 0
  * (unicast) and bit 1 of byte 1 must be 1 (locally administered).  Otherwise
@@ -43,6 +44,7 @@ union epoll_ref;
  * @icmp:	ICMP-specific reference part
  * @data:	Data handled by protocol handlers
  * @nsdir_fd:	netns dirfd for fallback timer checking if namespace is gone
+ * @queue:	vhost-user queue index for this fd
  * @u64:	Opaque reference for epoll_ctl() and epoll_wait()
  */
 union epoll_ref {
@@ -58,6 +60,7 @@ union epoll_ref {
 			union udp_listen_epoll_ref udp;
 			uint32_t data;
 			int nsdir_fd;
+			int queue;
 		};
 	};
 	uint64_t u64;
@@ -94,6 +97,7 @@ struct fqdn {
 enum passt_modes {
 	MODE_PASST,
 	MODE_PASTA,
+	MODE_VU,
 };
 
 /**
@@ -229,6 +233,7 @@ struct ip6_ctx {
  * @freebind:		Allow binding of non-local addresses for forwarding
  * @low_wmem:		Low probed net.core.wmem_max
  * @low_rmem:		Low probed net.core.rmem_max
+ * @vdev:		vhost-user device
  */
 struct ctx {
 	enum passt_modes mode;
@@ -291,6 +296,8 @@ struct ctx {
 
 	int low_wmem;
 	int low_rmem;
+
+	struct vu_dev *vdev;
 };
 
 void proto_update_l2_buf(const unsigned char *eth_d,
diff --git a/pcap.c b/pcap.c
index 23205ddfed84..3d623cfead77 100644
--- a/pcap.c
+++ b/pcap.c
@@ -143,7 +143,6 @@ void pcap_multiple(const struct iovec *iov, size_t frame_parts,
unsigned int n,
  * @iovcnt:	Number of buffers (@iov entries)
  * @offset:	Offset of the L2 frame within the full data length
  */
-/* cppcheck-suppress unusedFunction */
 void pcap_iov(const struct iovec *iov, size_t iovcnt, size_t offset)
 {
 	struct timespec now = { 0 };
diff --git a/tap.c b/tap.c
index 238f248ca45b..386f0bccd2fb 100644
--- a/tap.c
+++ b/tap.c
@@ -58,6 +58,8 @@
 #include "packet.h"
 #include "tap.h"
 #include "log.h"
+#include "vhost_user.h"
+#include "vu_common.h"
 
 /* IPv4 (plus ARP) and IPv6 message batches from tap/guest to IP handlers */
 static PACKET_POOL_NOINIT(pool_tap4, TAP_MSGS, pkt_buf);
@@ -78,16 +80,22 @@ void tap_send_single(const struct ctx *c, const void *data, size_t
l2len)
 	struct iovec iov[2];
 	size_t iovcnt = 0;
 
-	if (c->mode == MODE_PASST) {
+	switch (c->mode) {
+	case MODE_PASST:
 		iov[iovcnt] = IOV_OF_LVALUE(vnet_len);
 		iovcnt++;
-	}
-
-	iov[iovcnt].iov_base = (void *)data;
-	iov[iovcnt].iov_len = l2len;
-	iovcnt++;
+		/* fall through */
+	case MODE_PASTA:
+		iov[iovcnt].iov_base = (void *)data;
+		iov[iovcnt].iov_len = l2len;
+		iovcnt++;
 
-	tap_send_frames(c, iov, iovcnt, 1);
+		tap_send_frames(c, iov, iovcnt, 1);
+		break;
+	case MODE_VU:
+		vu_send_single(c, data, l2len);
+		break;
+	}
 }
 
 /**
@@ -414,10 +422,18 @@ size_t tap_send_frames(const struct ctx *c, const struct iovec
*iov,
 	if (!nframes)
 		return 0;
 
-	if (c->mode == MODE_PASTA)
+	switch (c->mode) {
+	case MODE_PASTA:
 		m = tap_send_frames_pasta(c, iov, bufs_per_frame, nframes);
-	else
+		break;
+	case MODE_PASST:
 		m = tap_send_frames_passt(c, iov, bufs_per_frame, nframes);
+		break;
+	case MODE_VU:
+		/* fall through */
+	default:
+		ASSERT(0);
+	}
 
 	if (m < nframes)
 		debug("tap: failed to send %zu frames of %zu",
@@ -976,7 +992,7 @@ void tap_add_packet(struct ctx *c, ssize_t l2len, char *p)
  * tap_sock_reset() - Handle closing or failure of connect AF_UNIX socket
  * @c:		Execution context
  */
-static void tap_sock_reset(struct ctx *c)
+void tap_sock_reset(struct ctx *c)
 {
 	info("Client connection closed%s", c->one_off ? ", exiting" :
"");
 
@@ -987,6 +1003,8 @@ static void tap_sock_reset(struct ctx *c)
 	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, c->fd_tap, NULL);
 	close(c->fd_tap);
 	c->fd_tap = -1;
+	if (c->mode == MODE_VU)
+		vu_cleanup(c->vdev);
 }
 
 /**
@@ -1207,6 +1225,11 @@ static void tap_backend_show_hints(struct ctx *c)
 		info("or qrap, for earlier qemu versions:");
 		info("    ./qrap 5 kvm ... -net socket,fd=5 -net nic,model=virtio");
 		break;
+	case MODE_VU:
+		info("You can start qemu with:");
+		info("    kvm ... -chardev socket,id=chr0,path=%s -netdev
vhost-user,id=netdev0,chardev=chr0 -device virtio-net,netdev=netdev0 -object
memory-backend-memfd,id=memfd0,share=on,size=$RAMSIZE -numa node,memdev=memfd0\n",
+		     c->sock_path);
+		break;
 	}
 }
 
@@ -1234,8 +1257,8 @@ static void tap_sock_unix_init(const struct ctx *c)
  */
 void tap_listen_handler(struct ctx *c, uint32_t events)
 {
-	union epoll_ref ref = { .type = EPOLL_TYPE_TAP_PASST };
 	struct epoll_event ev = { 0 };
+	union epoll_ref ref = { 0 };
 	int v = INT_MAX / 2;
 	struct ucred ucred;
 	socklen_t len;
@@ -1275,6 +1298,10 @@ void tap_listen_handler(struct ctx *c, uint32_t events)
 		trace("tap: failed to set SO_SNDBUF to %i", v);
 
 	ref.fd = c->fd_tap;
+	if (c->mode == MODE_VU)
+		ref.type = EPOLL_TYPE_VHOST_CMD;
+	else
+		ref.type = EPOLL_TYPE_TAP_PASST;
 	ev.events = EPOLLIN | EPOLLRDHUP;
 	ev.data.u64 = ref.u64;
 	epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap, &ev);
@@ -1341,7 +1368,7 @@ static void tap_sock_tun_init(struct ctx *c)
  * @base:	Buffer base
  * @size	Buffer size
  */
-static void tap_sock_update_pool(void *base, size_t size)
+void tap_sock_update_pool(void *base, size_t size)
 {
 	int i;
 
@@ -1361,7 +1388,10 @@ static void tap_sock_update_pool(void *base, size_t size)
  */
 void tap_backend_init(struct ctx *c)
 {
-	tap_sock_update_pool(pkt_buf, sizeof(pkt_buf));
+	if (c->mode == MODE_VU)
+		tap_sock_update_pool(NULL, 0);
+	else
+		tap_sock_update_pool(pkt_buf, sizeof(pkt_buf));
 
 	if (c->fd_tap != -1) { /* Passed as --fd */
 		struct epoll_event ev = { 0 };
@@ -1369,10 +1399,17 @@ void tap_backend_init(struct ctx *c)
 
 		ASSERT(c->one_off);
 		ref.fd = c->fd_tap;
-		if (c->mode == MODE_PASST)
+		switch (c->mode) {
+		case MODE_PASST:
 			ref.type = EPOLL_TYPE_TAP_PASST;
-		else
+			break;
+		case MODE_PASTA:
 			ref.type = EPOLL_TYPE_TAP_PASTA;
+			break;
+		case MODE_VU:
+			ref.type = EPOLL_TYPE_VHOST_CMD;
+			break;
+		}
 
 		ev.events = EPOLLIN | EPOLLRDHUP;
 		ev.data.u64 = ref.u64;
@@ -1380,9 +1417,14 @@ void tap_backend_init(struct ctx *c)
 		return;
 	}
 
-	if (c->mode == MODE_PASTA) {
+	switch (c->mode) {
+	case MODE_PASTA:
 		tap_sock_tun_init(c);
-	} else {
+		break;
+	case MODE_VU:
+		vu_init(c);
+		/* fall through */
+	case MODE_PASST:
 		tap_sock_unix_init(c);
 
 		/* In passt mode, we don't know the guest's MAC address until it
@@ -1390,6 +1432,7 @@ void tap_backend_init(struct ctx *c)
 		 * first packets will reach it.
 		 */
 		memset(&c->guest_mac, 0xff, sizeof(c->guest_mac));
+		break;
 	}
 
 	tap_backend_show_hints(c);
diff --git a/tap.h b/tap.h
index 8728cc5c09c3..dfbd8b9ebd72 100644
--- a/tap.h
+++ b/tap.h
@@ -40,7 +40,8 @@ static inline struct iovec tap_hdr_iov(const struct ctx *c,
  */
 static inline void tap_hdr_update(struct tap_hdr *thdr, size_t l2len)
 {
-	thdr->vnet_len = htonl(l2len);
+	if (thdr)
+		thdr->vnet_len = htonl(l2len);
 }
 
 void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
@@ -68,6 +69,8 @@ void tap_handler_pasta(struct ctx *c, uint32_t events,
 void tap_handler_passt(struct ctx *c, uint32_t events,
 		       const struct timespec *now);
 int tap_sock_unix_open(char *sock_path);
+void tap_sock_reset(struct ctx *c);
+void tap_sock_update_pool(void *base, size_t size);
 void tap_backend_init(struct ctx *c);
 void tap_flush_pools(void);
 void tap_handler(struct ctx *c, const struct timespec *now);
diff --git a/tcp.c b/tcp.c
index 5d9968847d20..2b547876d58a 100644
--- a/tcp.c
+++ b/tcp.c
@@ -304,6 +304,7 @@
 #include "flow_table.h"
 #include "tcp_internal.h"
 #include "tcp_buf.h"
+#include "tcp_vu.h"
 
 /* MSS rounding: see SET_MSS() */
 #define MSS_DEFAULT			536
@@ -1312,6 +1313,9 @@ int tcp_prepare_flags(const struct ctx *c, struct tcp_tap_conn
*conn,
 static int tcp_send_flag(const struct ctx *c, struct tcp_tap_conn *conn,
 			 int flags)
 {
+	if (c->mode == MODE_VU)
+		return tcp_vu_send_flag(c, conn, flags);
+
 	return tcp_buf_send_flag(c, conn, flags);
 }
 
@@ -1705,6 +1709,9 @@ static int tcp_sock_consume(const struct tcp_tap_conn *conn,
uint32_t ack_seq)
  */
 static int tcp_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
 {
+	if (c->mode == MODE_VU)
+		return tcp_vu_data_from_sock(c, conn);
+
 	return tcp_buf_data_from_sock(c, conn);
 }
 
diff --git a/tcp_vu.c b/tcp_vu.c
new file mode 100644
index 000000000000..be5027a1e921
--- /dev/null
+++ b/tcp_vu.c
@@ -0,0 +1,497 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* tcp_vu.c - TCP L2 vhost-user management functions
+ *
+ * Copyright Red Hat
+ * Author: Laurent Vivier &lt;lvivier(a)redhat.com&gt;
+ */
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+
+#include <sys/socket.h>
+
+#include <linux/virtio_net.h>
+
+#include "util.h"
+#include "ip.h"
+#include "passt.h"
+#include "siphash.h"
+#include "inany.h"
+#include "vhost_user.h"
+#include "tcp.h"
+#include "pcap.h"
+#include "flow.h"
+#include "tcp_conn.h"
+#include "flow_table.h"
+#include "tcp_vu.h"
+#include "tap.h"
+#include "tcp_internal.h"
+#include "checksum.h"
+#include "vu_common.h"
+#include <time.h>
+
+static struct iovec iov_vu[VIRTQUEUE_MAX_SIZE + 1];
+static struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
+static int head[VIRTQUEUE_MAX_SIZE + 1];
+static int head_cnt;
+
+/**
+ * tcp_vu_hdrlen() - return the size of the header in level 2 frame (TCP)
+ * @v6:		Set for IPv6 packet
+ *
+ * Return: Return the size of the header
+ */
+static size_t tcp_vu_hdrlen(bool v6)
+{
+	size_t hdrlen;
+
+	hdrlen = sizeof(struct virtio_net_hdr_mrg_rxbuf) +
+		 sizeof(struct ethhdr) + sizeof(struct tcphdr);
+
+	if (v6)
+		hdrlen += sizeof(struct ipv6hdr);
+	else
+		hdrlen += sizeof(struct iphdr);
+
+	return hdrlen;
+}
+
+/**
+ * tcp_vu_update_check() - Calculate TCP checksum
+ * @tapside:	Address information for one side of the flow
+ * @iov:	Pointer to the array of IO vectors
+ * @iov_cnt:	Length of the array
+ */
+static void tcp_vu_update_check(const struct flowside *tapside,
+			        struct iovec *iov, int iov_cnt)
+{
+	char *base = iov[0].iov_base;
+
+	if (inany_v4(&tapside->oaddr)) {
+		const struct iphdr *iph = vu_ip(base);
+
+		tcp_update_check_tcp4(iph, iov, iov_cnt,
+				      (char *)vu_payloadv4(base) - base);
+	} else {
+		const struct ipv6hdr *ip6h = vu_ip(base);
+
+		tcp_update_check_tcp6(ip6h, iov, iov_cnt,
+				      (char *)vu_payloadv6(base) - base);
+	}
+}
+
+/**
+ * tcp_vu_send_flag() - Send segment with flags to vhost-user (no payload)
+ * @c:		Execution context
+ * @conn:	Connection pointer
+ * @flags:	TCP flags: if not set, send segment only if ACK is due
+ *
+ * Return: negative error code on connection reset, 0 otherwise
+ */
+int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
+{
+	struct vu_dev *vdev = c->vdev;
+	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	const struct flowside *tapside = TAPFLOW(conn);
+	size_t l2len, l4len, optlen, hdrlen;
+	struct vu_virtq_element flags_elem[2];
+	struct tcp_payload_t *payload;
+	struct ipv6hdr *ip6h = NULL;
+	struct iovec flags_iov[2];
+	struct iphdr *iph = NULL;
+	struct ethhdr *eh;
+	uint32_t seq;
+	int elem_cnt;
+	int nb_ack;
+	int ret;
+
+	hdrlen = tcp_vu_hdrlen(CONN_V6(conn));
+
+	vu_set_element(&flags_elem[0], NULL, &flags_iov[0]);
+
+	elem_cnt = vu_collect(vdev, vq, &flags_elem[0], 1,
+			      hdrlen + sizeof(struct tcp_syn_opts), NULL);
+	if (elem_cnt != 1)
+		return -1;
+
+	ASSERT(flags_elem[0].in_sg[0].iov_len >=
+	       hdrlen + sizeof(struct tcp_syn_opts));
+
+	vu_set_vnethdr(vdev, flags_elem[0].in_sg[0].iov_base, 1);
+
+	eh = vu_eth(flags_elem[0].in_sg[0].iov_base);
+
+	memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest));
+	memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source));
+
+	if (CONN_V4(conn)) {
+		eh->h_proto = htons(ETH_P_IP);
+
+		iph = vu_ip(flags_elem[0].in_sg[0].iov_base);
+		*iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);
+
+		payload = vu_payloadv4(flags_elem[0].in_sg[0].iov_base);
+	} else {
+		eh->h_proto = htons(ETH_P_IPV6);
+
+		ip6h = vu_ip(flags_elem[0].in_sg[0].iov_base);
+		*ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);
+		payload = vu_payloadv6(flags_elem[0].in_sg[0].iov_base);
+	}
+
+	memset(&payload->th, 0, sizeof(payload->th));
+	payload->th.doff = offsetof(struct tcp_payload_t, data) / 4;
+	payload->th.ack = 1;
+
+	seq = conn->seq_to_tap;
+	ret = tcp_prepare_flags(c, conn, flags, &payload->th,
+				(struct tcp_syn_opts *)payload->data,
+				&optlen);
+	if (ret <= 0) {
+		vu_queue_rewind(vq, 1);
+		return ret;
+	}
+
+	if (CONN_V4(conn)) {
+		l4len = tcp_fill_headers4(conn, NULL, iph, payload, optlen,
+					  NULL, seq, true);
+		l2len = sizeof(*iph);
+	} else {
+		l4len = tcp_fill_headers6(conn, NULL, ip6h, payload, optlen,
+					  seq, true);
+		l2len = sizeof(*ip6h);
+	}
+	l2len += l4len + sizeof(struct ethhdr);
+
+	flags_elem[0].in_sg[0].iov_len = l2len +
+				   sizeof(struct virtio_net_hdr_mrg_rxbuf);
+	if (*c->pcap) {
+		tcp_vu_update_check(tapside, &flags_elem[0].in_sg[0], 1);
+		pcap_iov(&flags_elem[0].in_sg[0], 1,
+			 sizeof(struct virtio_net_hdr_mrg_rxbuf));
+	}
+	nb_ack = 1;
+
+	if (flags & DUP_ACK) {
+		vu_set_element(&flags_elem[1], NULL, &flags_iov[1]);
+
+		elem_cnt = vu_collect(vdev, vq, &flags_elem[1], 1,
+				      flags_elem[0].in_sg[0].iov_len, NULL);
+		if (elem_cnt == 1 &&
+		    flags_elem[1].in_sg[0].iov_len >=
+		    flags_elem[0].in_sg[0].iov_len) {
+			memcpy(flags_elem[1].in_sg[0].iov_base,
+			       flags_elem[0].in_sg[0].iov_base,
+			       flags_elem[0].in_sg[0].iov_len);
+			nb_ack++;
+
+			if (*c->pcap) {
+				pcap_iov(&flags_elem[1].in_sg[0], 1,
+					 sizeof(struct virtio_net_hdr_mrg_rxbuf));
+			}
+		}
+	}
+
+	vu_flush(vdev, vq, flags_elem, nb_ack);
+
+	return 0;
+}
+
+/** tcp_vu_sock_recv() - Receive datastream from socket into vhost-user buffers
+ * @c:			Execution context
+ * @conn:		Connection pointer
+ * @v6:			Set for IPv6 connections
+ * @already_sent:	Number of bytes already sent
+ * @fillsize:		Maximum bytes to fill in guest-side receiving window
+ * @iov_cnt:		number of iov (output)
+ *
+ * Return: Number of iov entries used to store the data or negative error code
+ */
+static ssize_t tcp_vu_sock_recv(const struct ctx *c,
+				const struct tcp_tap_conn *conn, bool v6,
+				uint32_t already_sent, size_t fillsize,
+				int *iov_cnt)
+{
+	struct vu_dev *vdev = c->vdev;
+	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	struct msghdr mh_sock = { 0 };
+	uint16_t mss = MSS_GET(conn);
+	int s = conn->sock;
+	ssize_t ret, len;
+	size_t hdrlen;
+	int elem_cnt;
+	int i;
+
+	*iov_cnt = 0;
+
+	hdrlen = tcp_vu_hdrlen(v6);
+
+	vu_init_elem(elem, &iov_vu[1], VIRTQUEUE_MAX_SIZE);
+
+	elem_cnt = 0;
+	head_cnt = 0;
+	while (fillsize > 0 && elem_cnt < VIRTQUEUE_MAX_SIZE) {
+		struct iovec *iov;
+		size_t frame_size, dlen;
+		int cnt;
+
+		cnt = vu_collect(vdev, vq, &elem[elem_cnt],
+				 VIRTQUEUE_MAX_SIZE - elem_cnt,
+				 MIN(mss, fillsize) + hdrlen, &frame_size);
+		if (cnt == 0)
+			break;
+
+		dlen = frame_size - hdrlen;
+
+		/* reserve space for headers in iov */
+		iov = &elem[elem_cnt].in_sg[0];
+		ASSERT(iov->iov_len >= hdrlen);
+		iov->iov_base = (char *)iov->iov_base + hdrlen;
+		iov->iov_len -= hdrlen;
+		head[head_cnt++] = elem_cnt;
+
+		fillsize -= dlen;
+		elem_cnt += cnt;
+	}
+
+	if (peek_offset_cap) {
+		mh_sock.msg_iov = iov_vu + 1;
+		mh_sock.msg_iovlen = elem_cnt;
+	} else {
+		iov_vu[0].iov_base = tcp_buf_discard;
+		iov_vu[0].iov_len = already_sent;
+
+		mh_sock.msg_iov = iov_vu;
+		mh_sock.msg_iovlen = elem_cnt + 1;
+	}
+
+	do
+		ret = recvmsg(s, &mh_sock, MSG_PEEK);
+	while (ret < 0 && errno == EINTR);
+
+	if (ret < 0) {
+		vu_queue_rewind(vq, elem_cnt);
+		return -errno;
+	}
+
+	if (!peek_offset_cap)
+		ret -= already_sent;
+
+	/* adjust iov number and length of the last iov */
+	len = ret;
+	for (i = 0; len && i < elem_cnt; i++) {
+		struct iovec *iov = &elem[i].in_sg[0];
+
+		if (iov->iov_len > (size_t)len)
+			iov->iov_len = len;
+
+		len -= iov->iov_len;
+	}
+	/* adjust head count */
+	while (head_cnt > 0 && head[head_cnt - 1] > i)
+		head_cnt--;
+	/* mark end of array */
+	head[head_cnt] = i;
+	*iov_cnt = i;
+
+	/* release unused buffers */
+	vu_queue_rewind(vq, elem_cnt - i);
+
+	/* restore space for headers in iov */
+	for (i = 0; i < head_cnt; i++) {
+		struct iovec *iov = &elem[head[i]].in_sg[0];
+
+		iov->iov_base = (char *)iov->iov_base - hdrlen;
+		iov->iov_len += hdrlen;
+	}
+
+	return ret;
+}
+
+/**
+ * tcp_vu_prepare() - Prepare the frame header
+ * @c:		Execution context
+ * @conn:	Connection pointer
+ * @first:	Pointer to the array of IO vectors
+ * @dlen:	Packet data length
+ * @check:	Checksum, if already known
+ */
+static void tcp_vu_prepare(const struct ctx *c,
+			   struct tcp_tap_conn *conn, char *base,
+			   size_t dlen, const uint16_t **check)
+{
+	const struct flowside *toside = TAPFLOW(conn);
+	struct tcp_payload_t *payload;
+	struct ipv6hdr *ip6h = NULL;
+	struct iphdr *iph = NULL;
+	struct ethhdr *eh;
+
+	/* we guess the first iovec provided by the guest can embed
+	 * all the headers needed by L2 frame
+	 */
+
+	eh = vu_eth(base);
+
+	memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest));
+	memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source));
+
+	/* initialize header */
+
+	if (inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr)) {
+		eh->h_proto = htons(ETH_P_IP);
+
+		iph = vu_ip(base);
+		*iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);
+		payload = vu_payloadv4(base);
+	} else {
+		eh->h_proto = htons(ETH_P_IPV6);
+
+		ip6h = vu_ip(base);
+		*ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);
+
+		payload = vu_payloadv6(base);
+	}
+
+	memset(&payload->th, 0, sizeof(payload->th));
+	payload->th.doff = offsetof(struct tcp_payload_t, data) / 4;
+	payload->th.ack = 1;
+
+	if (inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr)) {
+		tcp_fill_headers4(conn, NULL, iph, payload, dlen,
+				  *check, conn->seq_to_tap, true);
+		*check = &iph->check;
+	} else {
+		tcp_fill_headers6(conn, NULL, ip6h, payload, dlen,
+				  conn->seq_to_tap, true);
+	}
+}
+
+/**
+ * tcp_vu_data_from_sock() - Handle new data from socket, queue to vhost-user,
+ *			     in window
+ * @c:		Execution context
+ * @conn:	Connection pointer
+ *
+ * Return: Negative on connection reset, 0 otherwise
+ */
+int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
+{
+	uint32_t wnd_scaled = conn->wnd_from_tap << conn->ws_from_tap;
+	struct vu_dev *vdev = c->vdev;
+	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	const struct flowside *tapside = TAPFLOW(conn);
+	size_t fillsize, hdrlen;
+	int v6 = CONN_V6(conn);
+	uint32_t already_sent;
+	const uint16_t *check;
+	int i, iov_cnt;
+	ssize_t len;
+
+	if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
+		debug("Got packet, but RX virtqueue not usable yet");
+		return 0;
+	}
+
+	already_sent = conn->seq_to_tap - conn->seq_ack_from_tap;
+
+	if (SEQ_LT(already_sent, 0)) {
+		/* RFC 761, section 2.1. */
+		flow_trace(conn, "ACK sequence gap: ACK for %u, sent: %u",
+			   conn->seq_ack_from_tap, conn->seq_to_tap);
+		conn->seq_to_tap = conn->seq_ack_from_tap;
+		already_sent = 0;
+		if (tcp_set_peek_offset(conn->sock, 0)) {
+			tcp_rst(c, conn);
+			return -1;
+		}
+	}
+
+	if (!wnd_scaled || already_sent >= wnd_scaled) {
+		conn_flag(c, conn, STALLED);
+		conn_flag(c, conn, ACK_FROM_TAP_DUE);
+		return 0;
+	}
+
+	/* Set up buffer descriptors we'll fill completely and partially. */
+
+	fillsize = wnd_scaled - already_sent;
+
+	/* collect the buffers from vhost-user and fill them with the
+	 * data from the socket
+	 */
+	len = tcp_vu_sock_recv(c, conn, v6, already_sent, fillsize, &iov_cnt);
+	if (len < 0) {
+		if (len != -EAGAIN && len != -EWOULDBLOCK) {
+			tcp_rst(c, conn);
+			return len;
+		}
+		return 0;
+	}
+
+	if (!len) {
+		if (already_sent) {
+			conn_flag(c, conn, STALLED);
+		} else if ((conn->events & (SOCK_FIN_RCVD | TAP_FIN_SENT)) ==
+			   SOCK_FIN_RCVD) {
+			int ret = tcp_vu_send_flag(c, conn, FIN | ACK);
+			if (ret) {
+				tcp_rst(c, conn);
+				return ret;
+			}
+
+			conn_event(c, conn, TAP_FIN_SENT);
+		}
+
+		return 0;
+	}
+
+	conn_flag(c, conn, ~STALLED);
+
+	/* Likely, some new data was acked too. */
+	tcp_update_seqack_wnd(c, conn, false, NULL);
+
+	/* initialize headers */
+	/* iov_vu is an array of buffers and the buffer size can be
+	 * smaller than the frame size we want to use but with
+	 * num_buffer we can merge several virtio iov buffers in one packet
+	 * we need only to set the packet headers in the first iov and
+	 * num_buffer to the number of iov entries
+	 */
+
+	hdrlen = tcp_vu_hdrlen(v6);
+	for (i = 0, check = NULL; i < head_cnt; i++) {
+		struct iovec *iov = &elem[head[i]].in_sg[0];
+		int buf_cnt = head[i + 1] - head[i];
+		int dlen = iov_size(iov, buf_cnt) - hdrlen;
+
+		vu_set_vnethdr(vdev, iov->iov_base, buf_cnt);
+
+		/* we compute IPv4 header checksum only for the
+		 * first and the last, all other checksums are the
+		 * same as the first one
+		 */
+		if (i + 1 == head_cnt)
+			check = NULL;
+
+		tcp_vu_prepare(c, conn, iov->iov_base, dlen, &check);
+
+		if (*c->pcap) {
+			tcp_vu_update_check(tapside, iov, buf_cnt);
+			pcap_iov(iov, buf_cnt,
+				 sizeof(struct virtio_net_hdr_mrg_rxbuf));
+		}
+
+		conn->seq_to_tap += dlen;
+	}
+
+	/* send packets */
+	vu_flush(vdev, vq, elem, iov_cnt);
+
+	conn_flag(c, conn, ACK_FROM_TAP_DUE);
+
+	return 0;
+}
diff --git a/tcp_vu.h b/tcp_vu.h
new file mode 100644
index 000000000000..6ab6057f352a
--- /dev/null
+++ b/tcp_vu.h
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright Red Hat
+ * Author: Laurent Vivier &lt;lvivier(a)redhat.com&gt;
+ */
+
+#ifndef TCP_VU_H
+#define TCP_VU_H
+
+int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags);
+int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn);
+
+#endif  /*TCP_VU_H */
diff --git a/udp.c b/udp.c
index 9718ed85e796..5b0093a15a30 100644
--- a/udp.c
+++ b/udp.c
@@ -110,6 +110,7 @@
 #include "log.h"
 #include "flow_table.h"
 #include "udp_internal.h"
+#include "udp_vu.h"
 
 /* "Spliced" sockets indexed by bound port (host order) */
 static int udp_splice_ns  [IP_VERSIONS][NUM_PORTS];
@@ -628,6 +629,11 @@ void udp_listen_sock_handler(const struct ctx *c,
 			     union epoll_ref ref, uint32_t events,
 			     const struct timespec *now)
 {
+	if (c->mode == MODE_VU) {
+		udp_vu_listen_sock_handler(c, ref, events, now);
+		return;
+	}
+
 	udp_buf_listen_sock_handler(c, ref, events, now);
 }
 
@@ -698,6 +704,11 @@ static void udp_buf_reply_sock_handler(const struct ctx *c, union
epoll_ref ref,
 void udp_reply_sock_handler(const struct ctx *c, union epoll_ref ref,
 			    uint32_t events, const struct timespec *now)
 {
+	if (c->mode == MODE_VU) {
+		udp_vu_reply_sock_handler(c, ref, events, now);
+		return;
+	}
+
 	udp_buf_reply_sock_handler(c, ref, events, now);
 }
 
diff --git a/udp_vu.c b/udp_vu.c
new file mode 100644
index 000000000000..c911022546c1
--- /dev/null
+++ b/udp_vu.c
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* udp_vu.c - UDP L2 vhost-user management functions
+ *
+ * Copyright Red Hat
+ * Author: Laurent Vivier &lt;lvivier(a)redhat.com&gt;
+ */
+
+#include <unistd.h>
+#include <assert.h>
+#include <net/ethernet.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <sys/uio.h>
+#include <linux/virtio_net.h>
+
+#include "checksum.h"
+#include "util.h"
+#include "ip.h"
+#include "siphash.h"
+#include "inany.h"
+#include "passt.h"
+#include "pcap.h"
+#include "log.h"
+#include "vhost_user.h"
+#include "udp_internal.h"
+#include "flow.h"
+#include "flow_table.h"
+#include "udp_flow.h"
+#include "udp_vu.h"
+#include "vu_common.h"
+
+static struct iovec     iov_vu		[VIRTQUEUE_MAX_SIZE];
+static struct vu_virtq_element	elem		[VIRTQUEUE_MAX_SIZE];
+
+/**
+ * udp_vu_hdrlen() - return the size of the header in level 2 frame (UDP)
+ * @v6:		Set for IPv6 packet
+ *
+ * Return: Return the size of the header
+ */
+static size_t udp_vu_hdrlen(bool v6)
+{
+	size_t hdrlen;
+
+	hdrlen = sizeof(struct virtio_net_hdr_mrg_rxbuf) +
+		 sizeof(struct ethhdr) + sizeof(struct udphdr);
+
+	if (v6)
+		hdrlen += sizeof(struct ipv6hdr);
+	else
+		hdrlen += sizeof(struct iphdr);
+
+	return hdrlen;
+}
+
+/**
+ * udp_vu_sock_info() - get socket information
+ * @s:		Socket to get information from
+ * @s_in:	Socket address (output)
+ *
+ * Return: 0 if socket address can be read, -1 otherwise
+ */
+static int udp_vu_sock_info(int s, union sockaddr_inany *s_in)
+{
+	struct msghdr msg = {
+		.msg_name = s_in,
+		.msg_namelen = sizeof(union sockaddr_inany),
+	};
+
+	return recvmsg(s, &msg, MSG_PEEK | MSG_DONTWAIT);
+}
+
+/**
+ * udp_vu_sock_recv() - Receive datagrams from socket into vhost-user buffers
+ * @c:		Execution context
+ * @s:		Socket to receive from
+ * @events:	epoll events bitmap
+ * @v6:		Set for IPv6 connections
+ * @dlen:	Size of received data (output)
+ *
+ * Return: Number of iov entries used to store the datagram
+ */
+static int udp_vu_sock_recv(const struct ctx *c, int s, uint32_t events,
+			    bool v6, ssize_t *dlen)
+{
+	struct vu_dev *vdev = c->vdev;
+	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	int iov_cnt, idx, iov_used;
+	struct msghdr msg  = { 0 };
+	size_t off, hdrlen;
+
+	ASSERT(!c->no_udp);
+
+	if (!(events & EPOLLIN))
+		return 0;
+
+	/* compute L2 header length */
+	hdrlen = udp_vu_hdrlen(v6);
+
+	vu_init_elem(elem, iov_vu, VIRTQUEUE_MAX_SIZE);
+
+	iov_cnt = vu_collect(vdev, vq, elem, VIRTQUEUE_MAX_SIZE,
+			     IP_MAX_MTU - sizeof(struct udphdr) + hdrlen,
+			     NULL);
+	if (iov_cnt == 0)
+		return 0;
+
+	/* reserve space for the headers */
+	ASSERT(iov_vu[0].iov_len >= hdrlen);
+	iov_vu[0].iov_base = (char *)iov_vu[0].iov_base + hdrlen;
+	iov_vu[0].iov_len -= hdrlen;
+
+	/* read data from the socket */
+	msg.msg_iov = iov_vu;
+	msg.msg_iovlen = iov_cnt;
+
+	*dlen = recvmsg(s, &msg, 0);
+	if (*dlen < 0) {
+		vu_queue_rewind(vq, iov_cnt);
+		return 0;
+	}
+
+	/* restore the pointer to the headers address */
+	iov_vu[0].iov_base = (char *)iov_vu[0].iov_base - hdrlen;
+	iov_vu[0].iov_len += hdrlen;
+
+	/* count the numbers of buffer filled by recvmsg() */
+	idx = iov_skip_bytes(iov_vu, iov_cnt, *dlen + hdrlen, &off);
+
+	/* adjust last iov length */
+	if (idx < iov_cnt)
+		iov_vu[idx].iov_len = off;
+	iov_used = idx + !!off;
+
+	vu_set_vnethdr(vdev, iov_vu[0].iov_base, iov_used);
+
+	/* release unused buffers */
+	vu_queue_rewind(vq, iov_cnt - iov_used);
+
+	return iov_used;
+}
+
+/**
+ * udp_vu_prepare() - Prepare the packet header
+ * @c:		Execution context
+ * @toside:	Address information for one side of the flow
+ * @dlen:	Packet data length
+ *
+ * Return: Layer-4 length
+ */
+static size_t udp_vu_prepare(const struct ctx *c,
+			     const struct flowside *toside, ssize_t dlen)
+{
+	struct ethhdr *eh;
+	size_t l4len;
+
+	/* ethernet header */
+	eh = vu_eth(iov_vu[0].iov_base);
+
+	memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest));
+	memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source));
+
+	/* initialize header */
+	if (inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr)) {
+		struct iphdr *iph = vu_ip(iov_vu[0].iov_base);
+		struct udp_payload_t *bp = vu_payloadv4(iov_vu[0].iov_base);
+
+		eh->h_proto = htons(ETH_P_IP);
+
+		*iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_UDP);
+
+		l4len = udp_update_hdr4(iph, bp, toside, dlen, true);
+	} else {
+		struct ipv6hdr *ip6h = vu_ip(iov_vu[0].iov_base);
+		struct udp_payload_t *bp = vu_payloadv6(iov_vu[0].iov_base);
+
+		eh->h_proto = htons(ETH_P_IPV6);
+
+		*ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_UDP);
+
+		l4len = udp_update_hdr6(ip6h, bp, toside, dlen, true);
+	}
+
+	return l4len;
+}
+
+/**
+ * udp_vu_csum() - Calculate and set checksum for a UDP packet
+ * @toside:	Address information for one side of the flow
+ * @iov_used:	Number of used iov_vu items
+ */
+static void udp_vu_csum(const struct flowside *toside, int iov_used)
+{
+	const struct in_addr *src4 = inany_v4(&toside->oaddr);
+	const struct in_addr *dst4 = inany_v4(&toside->eaddr);
+	char *base = iov_vu[0].iov_base;
+	struct udp_payload_t *bp;
+
+	if (src4 && dst4) {
+		bp = vu_payloadv4(base);
+		csum_udp4(&bp->uh, *src4, *dst4, iov_vu, iov_used,
+			  (char *)&bp->data - base);
+	} else {
+		bp = vu_payloadv6(base);
+		csum_udp6(&bp->uh, &toside->oaddr.a6, &toside->eaddr.a6,
+			  iov_vu, iov_used, (char *)&bp->data - base);
+	}
+}
+
+/**
+ * udp_vu_listen_sock_handler() - Handle new data from socket
+ * @c:		Execution context
+ * @ref:	epoll reference
+ * @events:	epoll events bitmap
+ * @now:	Current timestamp
+ */
+void udp_vu_listen_sock_handler(const struct ctx *c, union epoll_ref ref,
+				uint32_t events, const struct timespec *now)
+{
+	struct vu_dev *vdev = c->vdev;
+	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	int i;
+
+	if (udp_sock_errs(c, ref.fd, events) < 0) {
+		err("UDP: Unrecoverable error on listening socket:"
+		    " (%s port %hu)", pif_name(ref.udp.pif), ref.udp.port);
+		return;
+	}
+
+	for (i = 0; i < UDP_MAX_FRAMES; i++) {
+		const struct flowside *toside;
+		union sockaddr_inany s_in;
+		flow_sidx_t sidx;
+		uint8_t pif;
+		ssize_t dlen;
+		int iov_used;
+		bool v6;
+
+		if (udp_vu_sock_info(ref.fd, &s_in) < 0)
+			break;
+
+		sidx = udp_flow_from_sock(c, ref, &s_in, now);
+		pif = pif_at_sidx(sidx);
+
+		if (pif != PIF_TAP) {
+			if (flow_sidx_valid(sidx)) {
+				flow_sidx_t fromsidx = flow_sidx_opposite(sidx);
+				struct udp_flow *uflow = udp_at_sidx(sidx);
+
+				flow_err(uflow,
+					"No support for forwarding UDP from %s to %s",
+					pif_name(pif_at_sidx(fromsidx)),
+					pif_name(pif));
+			} else {
+				debug("Discarding 1 datagram without flow");
+			}
+
+			continue;
+		}
+
+		toside = flowside_at_sidx(sidx);
+
+		v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
+
+		iov_used = udp_vu_sock_recv(c, ref.fd, events, v6, &dlen);
+		if (iov_used <= 0)
+			break;
+
+		udp_vu_prepare(c, toside, dlen);
+		if (*c->pcap) {
+			udp_vu_csum(toside, iov_used);
+			pcap_iov(iov_vu, iov_used,
+				 sizeof(struct virtio_net_hdr_mrg_rxbuf));
+		}
+		vu_flush(vdev, vq, elem, iov_used);
+	}
+}
+
+/**
+ * udp_vu_reply_sock_handler() - Handle new data from flow specific socket
+ * @c:		Execution context
+ * @ref:	epoll reference
+ * @events:	epoll events bitmap
+ * @now:	Current timestamp
+ */
+void udp_vu_reply_sock_handler(const struct ctx *c, union epoll_ref ref,
+			        uint32_t events, const struct timespec *now)
+{
+	flow_sidx_t tosidx = flow_sidx_opposite(ref.flowside);
+	const struct flowside *toside = flowside_at_sidx(tosidx);
+	struct udp_flow *uflow = udp_at_sidx(ref.flowside);
+	int from_s = uflow->s[ref.flowside.sidei];
+	struct vu_dev *vdev = c->vdev;
+	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	int i;
+
+	ASSERT(!c->no_udp);
+
+	if (udp_sock_errs(c, from_s, events) < 0) {
+		flow_err(uflow, "Unrecoverable error on reply socket");
+		flow_err_details(uflow);
+		udp_flow_close(c, uflow);
+		return;
+	}
+
+	for (i = 0; i < UDP_MAX_FRAMES; i++) {
+		uint8_t topif = pif_at_sidx(tosidx);
+		ssize_t dlen;
+		int iov_used;
+		bool v6;
+
+		ASSERT(uflow);
+
+		if (topif != PIF_TAP) {
+			uint8_t frompif = pif_at_sidx(ref.flowside);
+
+			flow_err(uflow,
+				 "No support for forwarding UDP from %s to %s",
+				 pif_name(frompif), pif_name(topif));
+			continue;
+		}
+
+		v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
+
+		iov_used = udp_vu_sock_recv(c, from_s, events, v6, &dlen);
+		if (iov_used <= 0)
+			break;
+		flow_trace(uflow, "Received 1 datagram on reply socket");
+		uflow->ts = now->tv_sec;
+
+		udp_vu_prepare(c, toside, dlen);
+		if (*c->pcap) {
+			udp_vu_csum(toside, iov_used);
+			pcap_iov(iov_vu, iov_used,
+				 sizeof(struct virtio_net_hdr_mrg_rxbuf));
+		}
+		vu_flush(vdev, vq, elem, iov_used);
+	}
+}
diff --git a/udp_vu.h b/udp_vu.h
new file mode 100644
index 000000000000..ba7018d3bf01
--- /dev/null
+++ b/udp_vu.h
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright Red Hat
+ * Author: Laurent Vivier &lt;lvivier(a)redhat.com&gt;
+ */
+
+#ifndef UDP_VU_H
+#define UDP_VU_H
+
+void udp_vu_listen_sock_handler(const struct ctx *c, union epoll_ref ref,
+				uint32_t events, const struct timespec *now);
+void udp_vu_reply_sock_handler(const struct ctx *c, union epoll_ref ref,
+			       uint32_t events, const struct timespec *now);
+#endif /* UDP_VU_H */
diff --git a/vhost_user.c b/vhost_user.c
index 89627a227ff1..51c90db10e7b 100644
--- a/vhost_user.c
+++ b/vhost_user.c
@@ -48,12 +48,13 @@
 /* vhost-user version we are compatible with */
 #define VHOST_USER_VERSION 1
 
+static struct vu_dev vdev_storage;
+
 /**
  * vu_print_capabilities() - print vhost-user capabilities
  * 			     this is part of the vhost-user backend
  * 			     convention.
  */
-/* cppcheck-suppress unusedFunction */
 void vu_print_capabilities(void)
 {
 	info("{");
@@ -163,9 +164,7 @@ static void vmsg_close_fds(const struct vhost_user_msg *vmsg)
  */
 static void vu_remove_watch(const struct vu_dev *vdev, int fd)
 {
-	/* Placeholder to add passt related code */
-	(void)vdev;
-	(void)fd;
+	epoll_ctl(vdev->context->epollfd, EPOLL_CTL_DEL, fd, NULL);
 }
 
 /**
@@ -487,6 +486,14 @@ static bool vu_set_mem_table_exec(struct vu_dev *vdev,
 		}
 	}
 
+	/* As vu_packet_check_range() has no access to the number of
+	 * memory regions, mark the end of the array with mmap_addr = 0
+	 */
+	ASSERT(vdev->nregions < VHOST_USER_MAX_RAM_SLOTS - 1);
+	vdev->regions[vdev->nregions].mmap_addr = 0;
+
+	tap_sock_update_pool(vdev->regions, 0);
+
 	return false;
 }
 
@@ -615,9 +622,16 @@ static bool vu_get_vring_base_exec(struct vu_dev *vdev,
  */
 static void vu_set_watch(const struct vu_dev *vdev, int idx)
 {
-	/* Placeholder to add passt related code */
-	(void)vdev;
-	(void)idx;
+	union epoll_ref ref = {
+		.type = EPOLL_TYPE_VHOST_KICK,
+		.fd = vdev->vq[idx].kick_fd,
+		.queue = idx
+	 };
+	struct epoll_event ev = { 0 };
+
+	ev.data.u64 = ref.u64;
+	ev.events = EPOLLIN;
+	epoll_ctl(vdev->context->epollfd, EPOLL_CTL_ADD, ref.fd, &ev);
 }
 
 /**
@@ -829,14 +843,14 @@ static bool vu_set_vring_enable_exec(struct vu_dev *vdev,
  * @c:		execution context
  * @vdev:	vhost-user device
  */
-/* cppcheck-suppress unusedFunction */
-void vu_init(struct ctx *c, struct vu_dev *vdev)
+void vu_init(struct ctx *c)
 {
 	int i;
 
-	vdev->context = c;
+	c->vdev = &vdev_storage;
+	c->vdev->context = c;
 	for (i = 0; i < VHOST_USER_MAX_QUEUES; i++) {
-		vdev->vq[i] = (struct vu_virtq){
+		c->vdev->vq[i] = (struct vu_virtq){
 			.call_fd = -1,
 			.kick_fd = -1,
 			.err_fd = -1,
@@ -849,7 +863,6 @@ void vu_init(struct ctx *c, struct vu_dev *vdev)
  * vu_cleanup() - Reset vhost-user device
  * @vdev:	vhost-user device
  */
-/* cppcheck-suppress unusedFunction */
 void vu_cleanup(struct vu_dev *vdev)
 {
 	unsigned int i;
@@ -896,8 +909,7 @@ void vu_cleanup(struct vu_dev *vdev)
  */
 static void vu_sock_reset(struct vu_dev *vdev)
 {
-	/* Placeholder to add passt related code */
-	(void)vdev;
+	tap_sock_reset(vdev->context);
 }
 
 static bool (*vu_handle[VHOST_USER_MAX])(struct vu_dev *vdev,
@@ -925,7 +937,6 @@ static bool (*vu_handle[VHOST_USER_MAX])(struct vu_dev *vdev,
  * @fd:		vhost-user message socket
  * @events:	epoll events
  */
-/* cppcheck-suppress unusedFunction */
 void vu_control_handler(struct vu_dev *vdev, int fd, uint32_t events)
 {
 	struct vhost_user_msg msg = { 0 };
diff --git a/vhost_user.h b/vhost_user.h
index 5af349ba58b8..464ba21e962f 100644
--- a/vhost_user.h
+++ b/vhost_user.h
@@ -183,7 +183,6 @@ struct vhost_user_msg {
  *
  * Return: true if the virqueue is enabled, false otherwise
  */
-/* cppcheck-suppress unusedFunction */
 static inline bool vu_queue_enabled(const struct vu_virtq *vq)
 {
 	return vq->enable;
@@ -195,14 +194,13 @@ static inline bool vu_queue_enabled(const struct vu_virtq *vq)
  *
  * Return: true if the virqueue is started, false otherwise
  */
-/* cppcheck-suppress unusedFunction */
 static inline bool vu_queue_started(const struct vu_virtq *vq)
 {
 	return vq->started;
 }
 
 void vu_print_capabilities(void);
-void vu_init(struct ctx *c, struct vu_dev *vdev);
+void vu_init(struct ctx *c);
 void vu_cleanup(struct vu_dev *vdev);
 void vu_control_handler(struct vu_dev *vdev, int fd, uint32_t events);
 #endif /* VHOST_USER_H */
diff --git a/virtio.c b/virtio.c
index b23a68c4917f..6a97435e2965 100644
--- a/virtio.c
+++ b/virtio.c
@@ -325,7 +325,6 @@ static bool vring_can_notify(const struct vu_dev *dev, struct vu_virtq
*vq)
  * @dev:	Vhost-user device
  * @vq:		Virtqueue
  */
-/* cppcheck-suppress unusedFunction */
 void vu_queue_notify(const struct vu_dev *dev, struct vu_virtq *vq)
 {
 	if (!vring_can_notify(dev, vq)) {
@@ -498,7 +497,6 @@ static int vu_queue_map_desc(struct vu_dev *dev, struct vu_virtq *vq,
unsigned i
  *
  * Return: -1 if there is an error, 0 otherwise
  */
-/* cppcheck-suppress unusedFunction */
 int vu_queue_pop(struct vu_dev *dev, struct vu_virtq *vq, struct vu_virtq_element *elem)
 {
 	unsigned int head;
@@ -556,7 +554,6 @@ void vu_queue_unpop(struct vu_virtq *vq)
  * @vq:		Virtqueue
  * @num:	Number of element to unpop
  */
-/* cppcheck-suppress unusedFunction */
 bool vu_queue_rewind(struct vu_virtq *vq, unsigned int num)
 {
 	if (num > vq->inuse)
@@ -609,7 +606,6 @@ void vu_queue_fill_by_index(struct vu_virtq *vq, unsigned int index,
  * @len:	Size of the element
  * @idx:	Used ring entry index
  */
-/* cppcheck-suppress unusedFunction */
 void vu_queue_fill(struct vu_virtq *vq, const struct vu_virtq_element *elem,
 		   unsigned int len, unsigned int idx)
 {
@@ -633,7 +629,6 @@ static inline void vring_used_idx_set(struct vu_virtq *vq, uint16_t
val)
  * @vq:		Virtqueue
  * @count:	Number of entry to flush
  */
-/* cppcheck-suppress unusedFunction */
 void vu_queue_flush(struct vu_virtq *vq, unsigned int count)
 {
 	uint16_t old, new;
diff --git a/vu_common.c b/vu_common.c
new file mode 100644
index 000000000000..2a18e9794b5c
--- /dev/null
+++ b/vu_common.c
@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright Red Hat
+ * Author: Laurent Vivier &lt;lvivier(a)redhat.com&gt;
+ *
+ * common_vu.c - vhost-user common UDP and TCP functions
+ */
+
+#include <unistd.h>
+#include <sys/uio.h>
+#include <sys/eventfd.h>
+#include <linux/virtio_net.h>
+
+#include "util.h"
+#include "passt.h"
+#include "tap.h"
+#include "vhost_user.h"
+#include "pcap.h"
+#include "vu_common.h"
+
+/**
+ * vu_packet_check_range() - Check if a given memory zone is contained in
+ * 			     a mapped guest memory region
+ * @buf:	Array of the available memory regions
+ * @offset:	Offset of data range in packet descriptor
+ * @size:	Length of desired data range
+ * @start:	Start of the packet descriptor
+ *
+ * Return: 0 if the zone is in a mapped memory region, -1 otherwise
+ */
+int vu_packet_check_range(void *buf, size_t offset, size_t len,
+			  const char *start)
+{
+	struct vu_dev_region *dev_region;
+
+	for (dev_region = buf; dev_region->mmap_addr; dev_region++) {
+		/* NOLINTNEXTLINE(performance-no-int-to-ptr) */
+		char *m = (char *)dev_region->mmap_addr;
+
+		if (m <= start &&
+		    start + offset + len <= m + dev_region->mmap_offset +
+					       dev_region->size)
+			return 0;
+	}
+
+	return -1;
+}
+
+/**
+ * vu_init_elem() - initialize an array of virtqueue elements with 1 iov in each
+ * @elem:	Array of virtqueue elements to initialize
+ * @iov:	Array of iovec to assign to virtqueue element
+ * @elem_cnt:	Number of virtqueue element
+ */
+void vu_init_elem(struct vu_virtq_element *elem, struct iovec *iov, int elem_cnt)
+{
+	int i;
+
+	for (i = 0; i < elem_cnt; i++)
+		vu_set_element(&elem[i], NULL, &iov[i]);
+}
+
+/**
+ * vu_collect() - collect virtio buffers from a given virtqueue
+ * @vdev:		vhost-user device
+ * @vq:			virtqueue to collect from
+ * @elem:		Array of virtqueue element
+ * 			each element must be initialized with one iovec entry
+ * 			in the in_sg array.
+ * @max_elem:		Number of virtqueue elements in the array
+ * @size:		Maximum size of the data in the frame
+ * @frame_size:		The total size of the buffers (output)
+ *
+ * Return: number of elements used to contain the frame
+ */
+int vu_collect(struct vu_dev *vdev, struct vu_virtq *vq,
+	       struct vu_virtq_element *elem, int max_elem,
+	       size_t size, size_t *frame_size)
+{
+	size_t current_size = 0;
+	int elem_cnt = 0;
+
+	while (current_size < size && elem_cnt < max_elem) {
+		struct iovec *iov;
+		int ret;
+
+		ret = vu_queue_pop(vdev, vq, &elem[elem_cnt]);
+		if (ret < 0)
+			break;
+
+		if (elem[elem_cnt].in_num < 1) {
+			warn("virtio-net receive queue contains no in buffers");
+			vu_queue_detach_element(vq);
+			break;
+		}
+
+		iov = &elem[elem_cnt].in_sg[0];
+
+		if (iov->iov_len > size - current_size)
+			iov->iov_len = size - current_size;
+
+		current_size += iov->iov_len;
+		elem_cnt++;
+
+		if (!vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
+			break;
+	}
+
+	if (frame_size)
+		*frame_size = current_size;
+
+	return elem_cnt;
+}
+
+/**
+ * vu_set_vnethdr() - set virtio-net headers
+ * @vdev:		vhost-user device
+ * @vnethdr:		Address of the header to set
+ * @num_buffers:	Number of guest buffers of the frame
+ */
+void vu_set_vnethdr(const struct vu_dev *vdev,
+		    struct virtio_net_hdr_mrg_rxbuf *vnethdr,
+		    int num_buffers)
+{
+	vnethdr->hdr = VU_HEADER;
+	if (vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
+		vnethdr->num_buffers = htole16(num_buffers);
+}
+
+/**
+ * vu_flush() - flush all the collected buffers to the vhost-user interface
+ * @vdev:	vhost-user device
+ * @vq:		vhost-user virtqueue
+ * @elem:	virtqueue elements array to send back to the virtqueue
+ * @elem_cnt:	Length of the array
+ */
+void vu_flush(const struct vu_dev *vdev, struct vu_virtq *vq,
+	      struct vu_virtq_element *elem, int elem_cnt)
+{
+	int i;
+
+	for (i = 0; i < elem_cnt; i++)
+		vu_queue_fill(vq, &elem[i], elem[i].in_sg[0].iov_len, i);
+
+	vu_queue_flush(vq, elem_cnt);
+	vu_queue_notify(vdev, vq);
+}
+
+/**
+ * vu_handle_tx() - Receive data from the TX virtqueue
+ * @vdev:	vhost-user device
+ * @index:	index of the virtqueue
+ * @now:	Current timestamp
+ */
+static void vu_handle_tx(struct vu_dev *vdev, int index,
+			 const struct timespec *now)
+{
+	struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
+	struct iovec out_sg[VIRTQUEUE_MAX_SIZE];
+	struct vu_virtq *vq = &vdev->vq[index];
+	int hdrlen = sizeof(struct virtio_net_hdr_mrg_rxbuf);
+	int out_sg_count;
+	int count;
+
+	ASSERT(VHOST_USER_IS_QUEUE_TX(index));
+
+	tap_flush_pools();
+
+	count = 0;
+	out_sg_count = 0;
+	while (count < VIRTQUEUE_MAX_SIZE) {
+		int ret;
+
+		vu_set_element(&elem[count], &out_sg[out_sg_count], NULL);
+		ret = vu_queue_pop(vdev, vq, &elem[count]);
+		if (ret < 0)
+			break;
+		out_sg_count += elem[count].out_num;
+
+		if (elem[count].out_num < 1) {
+			warn("virtio-net transmit queue contains no out buffers");
+			break;
+		}
+		ASSERT(elem[count].out_num == 1);
+
+		tap_add_packet(vdev->context,
+			       elem[count].out_sg[0].iov_len - hdrlen,
+			       (char *)elem[count].out_sg[0].iov_base + hdrlen);
+		count++;
+	}
+	tap_handler(vdev->context, now);
+
+	if (count) {
+		int i;
+
+		for (i = 0; i < count; i++)
+			vu_queue_fill(vq, &elem[i], 0, i);
+		vu_queue_flush(vq, count);
+		vu_queue_notify(vdev, vq);
+	}
+}
+
+/**
+ * vu_kick_cb() - Called on a kick event to start to receive data
+ * @vdev:	vhost-user device
+ * @ref:	epoll reference information
+ * @now:	Current timestamp
+ */
+void vu_kick_cb(struct vu_dev *vdev, union epoll_ref ref,
+		const struct timespec *now)
+{
+	eventfd_t kick_data;
+	ssize_t rc;
+
+	rc = eventfd_read(ref.fd, &kick_data);
+	if (rc == -1)
+		die_perror("vhost-user kick eventfd_read()");
+
+	debug("vhost-user: got kick_data: %016"PRIx64" idx: %d",
+	      kick_data, ref.queue);
+	if (VHOST_USER_IS_QUEUE_TX(ref.queue))
+		vu_handle_tx(vdev, ref.queue, now);
+}
+
+/**
+ * vu_send_single() - Send a buffer to the front-end using the RX virtqueue
+ * @c:		execution context
+ * @buf:	address of the buffer
+ * @size:	size of the buffer
+ *
+ * Return: number of bytes sent, -1 if there is an error
+ */
+int vu_send_single(const struct ctx *c, const void *buf, size_t size)
+{
+	struct vu_dev *vdev = c->vdev;
+	struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
+	struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
+	struct iovec in_sg[VIRTQUEUE_MAX_SIZE];
+	size_t total;
+	int elem_cnt;
+	int i;
+
+	debug("vu_send_single size %zu", size);
+
+	if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
+		debug("Got packet, but RX virtqueue not usable yet");
+		return -1;
+	}
+
+	vu_init_elem(elem, in_sg, VIRTQUEUE_MAX_SIZE);
+
+	size += sizeof(struct virtio_net_hdr_mrg_rxbuf);
+	elem_cnt = vu_collect(vdev, vq, elem, VIRTQUEUE_MAX_SIZE, size, &total);
+	if (total < size) {
+		debug("vu_send_single: no space to send the data "
+		      "elem_cnt %d size %zd", elem_cnt, total);
+		goto err;
+	}
+
+	vu_set_vnethdr(vdev, in_sg[0].iov_base, elem_cnt);
+
+	total -= sizeof(struct virtio_net_hdr_mrg_rxbuf);
+
+	/* copy data from the buffer to the iovec */
+	iov_from_buf(in_sg, elem_cnt, sizeof(struct virtio_net_hdr_mrg_rxbuf),
+		     buf, total);
+
+	if (*c->pcap) {
+		pcap_iov(in_sg, elem_cnt,
+			 sizeof(struct virtio_net_hdr_mrg_rxbuf));
+	}
+
+	vu_flush(vdev, vq, elem, elem_cnt);
+
+	debug("vhost-user sent %zu", total);
+
+	return total;
+err:
+	for (i = 0; i < elem_cnt; i++)
+		vu_queue_detach_element(vq);
+
+	return -1;
+}
diff --git a/vu_common.h b/vu_common.h
new file mode 100644
index 000000000000..901d97216c67
--- /dev/null
+++ b/vu_common.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright Red Hat
+ * Author: Laurent Vivier &lt;lvivier(a)redhat.com&gt;
+ *
+ * vhost-user common UDP and TCP functions
+ */
+
+#ifndef VU_COMMON_H
+#define VU_COMMON_H
+#include <linux/virtio_net.h>
+
+static inline void *vu_eth(void *base)
+{
+	return ((char *)base + sizeof(struct virtio_net_hdr_mrg_rxbuf));
+}
+
+static inline void *vu_ip(void *base)
+{
+	return (struct ethhdr *)vu_eth(base) + 1;
+}
+
+static inline void *vu_payloadv4(void *base)
+{
+	return (struct iphdr *)vu_ip(base) + 1;
+}
+
+static inline void *vu_payloadv6(void *base)
+{
+	return (struct ipv6hdr *)vu_ip(base) + 1;
+}
+
+/**
+ * vu_set_element() - Initialize a vu_virtq_element
+ * @elem:	Element to initialize
+ * @out_sg:	One out iovec entry to set in elem
+ * @in_sg:	One in iovec entry to set in elem
+ */
+static inline void vu_set_element(struct vu_virtq_element *elem,
+				  struct iovec *out_sg, struct iovec *in_sg)
+{
+	elem->out_num = !!out_sg;
+	elem->out_sg = out_sg;
+	elem->in_num = !!in_sg;
+	elem->in_sg = in_sg;
+}
+
+void vu_init_elem(struct vu_virtq_element *elem, struct iovec *iov,
+		  int elem_cnt);
+int vu_collect(struct vu_dev *vdev, struct vu_virtq *vq,
+	       struct vu_virtq_element *elem, int max_elem, size_t size,
+	       size_t *frame_size);
+void vu_set_vnethdr(const struct vu_dev *vdev,
+		    struct virtio_net_hdr_mrg_rxbuf *vnethdr,
+                    int num_buffers);
+void vu_flush(const struct vu_dev *vdev, struct vu_virtq *vq,
+	      struct vu_virtq_element *elem, int elem_cnt);
+void vu_kick_cb(struct vu_dev *vdev, union epoll_ref ref,
+		const struct timespec *now);
+int vu_send_single(const struct ctx *c, const void *buf, size_t size);
+#endif /* VU_COMMON_H */
-- 
2.47.0

From: Stefano Brivio <sbrivio(a)redhat.com>

Run functional and performance tests for vhost-user mode as well. For
functional tests, we add passt_vu and passt_vu_in_ns as symbolic links
to their non-vhost-user counterparts, as no differences are intended
but we want to distinguish them in test logs.

For performance tests, instead, we add separate perf/passt_vu_tcp and
perf/passt_vu_udp files, as we need longer test duration, as well as
higher UDP sending bandwidths and larger TCP windows, to actually get
the highest throughput vhost-user mode offers.

For valgrind tests, vhost-user mode needs two extra system calls:
statx and readlink. Add them as EXTRA_SYSCALLS for the valgrind
target.

Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>
---
 Makefile               |   3 +-
 test/lib/perf_report   |  15 +++
 test/lib/setup         |  77 ++++++++++++---
 test/lib/setup_ugly    |   2 +-
 test/passt_vu          |   1 +
 test/passt_vu_in_ns    |   1 +
 test/perf/passt_vu_tcp | 211 +++++++++++++++++++++++++++++++++++++++++
 test/perf/passt_vu_udp | 159 +++++++++++++++++++++++++++++++
 test/run               |  25 +++++
 test/two_guests_vu     |   1 +
 10 files changed, 479 insertions(+), 16 deletions(-)
 create mode 120000 test/passt_vu
 create mode 120000 test/passt_vu_in_ns
 create mode 100644 test/perf/passt_vu_tcp
 create mode 100644 test/perf/passt_vu_udp
 create mode 120000 test/two_guests_vu

diff --git a/Makefile b/Makefile
index faa5c23346ac..cb7448079de5 100644
--- a/Makefile
+++ b/Makefile
@@ -101,7 +101,8 @@ qrap: $(QRAP_SRCS) passt.h
 
 valgrind: EXTRA_SYSCALLS += rt_sigprocmask rt_sigtimedwait rt_sigaction	\
 			    rt_sigreturn getpid gettid kill clock_gettime mmap \
-			    mmap2 munmap open unlink gettimeofday futex
+			    mmap2 munmap open unlink gettimeofday futex statx \
+			    readlink
 valgrind: FLAGS += -g -DVALGRIND
 valgrind: all
 
diff --git a/test/lib/perf_report b/test/lib/perf_report
index d1ef50bfe0d5..c4ec817bcd1e 100755
--- a/test/lib/perf_report
+++ b/test/lib/perf_report
@@ -49,6 +49,21 @@ td:empty { visibility: hidden; }
 	__passt_tcp_LINE__ __passt_udp_LINE__
 </table>
 
+</li><li><p>passt with vhost-user support</p>
+<table class="passt" width="70%">
+	<tr>
+		<th/>
+		<th id="perf_passt_vu_tcp"
colspan="__passt_vu_tcp_cols__">TCP, __passt_vu_tcp_threads__ at
__passt_vu_tcp_freq__ GHz</th>
+		<th id="perf_passt_vu_udp"
colspan="__passt_vu_udp_cols__">UDP, __passt_vu_udp_threads__ at
__passt_vu_udp_freq__ GHz</th>
+	</tr>
+	<tr>
+		<td align="right">MTU:</td>
+		__passt_vu_tcp_header__
+		__passt_vu_udp_header__
+	</tr>
+	__passt_vu_tcp_LINE__ __passt_vu_udp_LINE__
+</table>
+
 <style type="text/CSS">
 table.pasta_local td { border: 0px solid; padding: 6px; line-height: 1; }
 table.pasta_local td { text-align: right; }
diff --git a/test/lib/setup b/test/lib/setup
index 5338393ce35c..580825f1f9a7 100755
--- a/test/lib/setup
+++ b/test/lib/setup
@@ -15,8 +15,7 @@
 
 INITRAMFS="${BASEPATH}/mbuto.img"
 VCPUS="$( [ $(nproc) -ge 8 ] && echo 6 || echo $(( $(nproc) / 2 + 1 ))
)"
-__mem_kib="$(sed -n 's/MemTotal:[ ]*\([0-9]*\) kB/\1/p'
/proc/meminfo)"
-VMEM="$((${__mem_kib} / 1024 / 4))"
+MEM_KIB="$(sed -n 's/MemTotal:[ ]*\([0-9]*\) kB/\1/p'
/proc/meminfo)"
 QEMU_ARCH="$(uname -m)"
 [ "${QEMU_ARCH}" = "i686" ] && QEMU_ARCH=i386
 
@@ -46,6 +45,7 @@ setup_passt() {
 	[ ${PCAP} -eq 1 ] && __opts="${__opts} -p ${LOGDIR}/passt.pcap"
 	[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
 	[ ${TRACE} -eq 1 ] && __opts="${__opts} --trace"
+	[ ${VHOST_USER} -eq 1 ] && __opts="${__opts} --vhost-user"
 
 	context_run passt "make clean"
 	context_run passt "make valgrind"
@@ -54,16 +54,29 @@ setup_passt() {
 	# pidfile isn't created until passt is listening
 	wait_for [ -f "${STATESETUP}/passt.pid" ]
 
+	__vmem="$((${MEM_KIB} / 1024 / 4))"
+	if [ ${VHOST_USER} -eq 1 ]; then
+		__vmem="$(((${__vmem} + 500) / 1000))G"
+		__qemu_netdev="						       \
+			-chardev socket,id=c,path=${STATESETUP}/passt.socket   \
+			-netdev vhost-user,id=v,chardev=c		       \
+			-device virtio-net,netdev=v			       \
+			-object memory-backend-memfd,id=m,share=on,size=${__vmem} \
+			-numa node,memdev=m"
+	else
+		__qemu_netdev="-device virtio-net-pci,netdev=s		       \
+			-netdev
stream,id=s,server=off,addr.type=unix,addr.path=${STATESETUP}/passt.socket"
+	fi
+
 	GUEST_CID=94557
 	context_run_bg qemu 'qemu-system-'"${QEMU_ARCH}"		   \
 		' -machine accel=kvm'                                      \
-		' -m '${VMEM}' -cpu host -smp '${VCPUS}                    \
+		' -m '${__vmem}' -cpu host -smp '${VCPUS}		   \
 		' -kernel '"${KERNEL}"					   \
 		' -initrd '${INITRAMFS}' -nographic -serial stdio'	   \
 		' -nodefaults'						   \
 		' -append "console=ttyS0 mitigations=off apparmor=0" '	   \
-		' -device virtio-net-pci,netdev=s0 '			   \
-		" -netdev
stream,id=s0,server=off,addr.type=unix,addr.path=${STATESETUP}/passt.socket " \
+		" ${__qemu_netdev}"					   \
 		" -pidfile ${STATESETUP}/qemu.pid"			   \
 		" -device vhost-vsock-pci,guest-cid=$GUEST_CID"
 
@@ -142,6 +155,7 @@ setup_passt_in_ns() {
 	[ ${PCAP} -eq 1 ] && __opts="${__opts} -p
${LOGDIR}/passt_in_pasta.pcap"
 	[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
 	[ ${TRACE} -eq 1 ] && __opts="${__opts} --trace"
+	[ ${VHOST_USER} -eq 1 ] && __opts="${__opts} --vhost-user"
 
 	if [ ${VALGRIND} -eq 1 ]; then
 		context_run passt "make clean"
@@ -154,17 +168,30 @@ setup_passt_in_ns() {
 	fi
 	wait_for [ -f "${STATESETUP}/passt.pid" ]
 
+	__vmem="$((${MEM_KIB} / 1024 / 4))"
+	if [ ${VHOST_USER} -eq 1 ]; then
+		__vmem="$(((${__vmem} + 500) / 1000))G"
+		__qemu_netdev="						       \
+			-chardev socket,id=c,path=${STATESETUP}/passt.socket   \
+			-netdev vhost-user,id=v,chardev=c		       \
+			-device virtio-net,netdev=v			       \
+			-object memory-backend-memfd,id=m,share=on,size=${__vmem} \
+			-numa node,memdev=m"
+	else
+		__qemu_netdev="-device virtio-net-pci,netdev=s		       \
+			-netdev
stream,id=s,server=off,addr.type=unix,addr.path=${STATESETUP}/passt.socket"
+	fi
+
 	GUEST_CID=94557
 	context_run_bg qemu 'qemu-system-'"${QEMU_ARCH}"		   \
 		' -machine accel=kvm'                                      \
 		' -M accel=kvm:tcg'                                        \
-		' -m '${VMEM}' -cpu host -smp '${VCPUS}                    \
+		' -m '${__vmem}' -cpu host -smp '${VCPUS}		   \
 		' -kernel '"${KERNEL}"					   \
 		' -initrd '${INITRAMFS}' -nographic -serial stdio'	   \
 		' -nodefaults'						   \
 		' -append "console=ttyS0 mitigations=off apparmor=0" '	   \
-		' -device virtio-net-pci,netdev=s0 '			   \
-		" -netdev
stream,id=s0,server=off,addr.type=unix,addr.path=${STATESETUP}/passt.socket " \
+		" ${__qemu_netdev}"					   \
 		" -pidfile ${STATESETUP}/qemu.pid"			   \
 		" -device vhost-vsock-pci,guest-cid=$GUEST_CID"
 
@@ -214,6 +241,7 @@ setup_two_guests() {
 	[ ${PCAP} -eq 1 ] && __opts="${__opts} -p ${LOGDIR}/passt_1.pcap"
 	[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
 	[ ${TRACE} -eq 1 ] && __opts="${__opts} --trace"
+	[ ${VHOST_USER} -eq 1 ] && __opts="${__opts} --vhost-user"
 
 	context_run_bg passt_1 "./passt -s ${STATESETUP}/passt_1.socket -P
${STATESETUP}/passt_1.pid -f ${__opts} -t 10001 -u 10001"
 	wait_for [ -f "${STATESETUP}/passt_1.pid" ]
@@ -222,33 +250,54 @@ setup_two_guests() {
 	[ ${PCAP} -eq 1 ] && __opts="${__opts} -p ${LOGDIR}/passt_2.pcap"
 	[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
 	[ ${TRACE} -eq 1 ] && __opts="${__opts} --trace"
+	[ ${VHOST_USER} -eq 1 ] && __opts="${__opts} --vhost-user"
 
 	context_run_bg passt_2 "./passt -s ${STATESETUP}/passt_2.socket -P
${STATESETUP}/passt_2.pid -f ${__opts} -t 10004 -u 10004"
 	wait_for [ -f "${STATESETUP}/passt_2.pid" ]
 
+	__vmem="$((${MEM_KIB} / 1024 / 4))"
+	if [ ${VHOST_USER} -eq 1 ]; then
+		__vmem="$(((${__vmem} + 500) / 1000))G"
+		__qemu_netdev1="					       \
+			-chardev socket,id=c,path=${STATESETUP}/passt_1.socket \
+			-netdev vhost-user,id=v,chardev=c		       \
+			-device virtio-net,netdev=v			       \
+			-object memory-backend-memfd,id=m,share=on,size=${__vmem} \
+			-numa node,memdev=m"
+		__qemu_netdev2="					       \
+			-chardev socket,id=c,path=${STATESETUP}/passt_2.socket \
+			-netdev vhost-user,id=v,chardev=c		       \
+			-device virtio-net,netdev=v			       \
+			-object memory-backend-memfd,id=m,share=on,size=${__vmem} \
+			-numa node,memdev=m"
+	else
+		__qemu_netdev1="-device virtio-net-pci,netdev=s		       \
+			-netdev
stream,id=s,server=off,addr.type=unix,addr.path=${STATESETUP}/passt_1.socket"
+		__qemu_netdev2="-device virtio-net-pci,netdev=s		       \
+			-netdev
stream,id=s,server=off,addr.type=unix,addr.path=${STATESETUP}/passt_2.socket"
+	fi
+
 	GUEST_1_CID=94557
 	context_run_bg qemu_1 'qemu-system-'"${QEMU_ARCH}"		     \
 		' -M accel=kvm:tcg'                                          \
-		' -m '${VMEM}' -cpu host -smp '${VCPUS}                      \
+		' -m '${__vmem}' -cpu host -smp '${VCPUS}		     \
 		' -kernel '"${KERNEL}"					     \
 		' -initrd '${INITRAMFS}' -nographic -serial stdio'	     \
 		' -nodefaults'						     \
 		' -append "console=ttyS0 mitigations=off apparmor=0" '	     \
-		' -device virtio-net-pci,netdev=s0 '			     \
-		" -netdev
stream,id=s0,server=off,addr.type=unix,addr.path=${STATESETUP}/passt_1.socket " \
+		" ${__qemu_netdev1}"					     \
 		" -pidfile ${STATESETUP}/qemu_1.pid"			     \
 		" -device vhost-vsock-pci,guest-cid=$GUEST_1_CID"
 
 	GUEST_2_CID=94558
 	context_run_bg qemu_2 'qemu-system-'"${QEMU_ARCH}"		     \
 		' -M accel=kvm:tcg'                                          \
-		' -m '${VMEM}' -cpu host -smp '${VCPUS}                      \
+		' -m '${__vmem}' -cpu host -smp '${VCPUS}		     \
 		' -kernel '"${KERNEL}"					     \
 		' -initrd '${INITRAMFS}' -nographic -serial stdio'	     \
 		' -nodefaults'						     \
 		' -append "console=ttyS0 mitigations=off apparmor=0" '	     \
-		' -device virtio-net-pci,netdev=s0 '			     \
-		" -netdev
stream,id=s0,server=off,addr.type=unix,addr.path=${STATESETUP}/passt_2.socket " \
+		" ${__qemu_netdev2}"					     \
 		" -pidfile ${STATESETUP}/qemu_2.pid"			     \
 		" -device vhost-vsock-pci,guest-cid=$GUEST_2_CID"
 
diff --git a/test/lib/setup_ugly b/test/lib/setup_ugly
index 4b2a0774de1d..2802cc3bb43b 100755
--- a/test/lib/setup_ugly
+++ b/test/lib/setup_ugly
@@ -33,7 +33,7 @@ setup_memory() {
 
 	pane_or_context_run guest 'qemu-system-$(uname -m)'		   \
 		' -machine accel=kvm'                                      \
-		' -m '${VMEM}' -cpu host -smp '${VCPUS}                    \
+		' -m '$((${MEM_KIB} / 1024 / 4))' -cpu host -smp '${VCPUS}         
          \
 		' -kernel ' "/boot/vmlinuz-$(uname -r)"			   \
 		' -initrd '${INITRAMFS_MEM}' -nographic -serial stdio'	   \
 		' -nodefaults'						   \
diff --git a/test/passt_vu b/test/passt_vu
new file mode 120000
index 000000000000..22f1840d1ad6
--- /dev/null
+++ b/test/passt_vu
@@ -0,0 +1 @@
+passt
\ No newline at end of file
diff --git a/test/passt_vu_in_ns b/test/passt_vu_in_ns
new file mode 120000
index 000000000000..3ff479e0436b
--- /dev/null
+++ b/test/passt_vu_in_ns
@@ -0,0 +1 @@
+passt_in_ns
\ No newline at end of file
diff --git a/test/perf/passt_vu_tcp b/test/perf/passt_vu_tcp
new file mode 100644
index 000000000000..b43400804e64
--- /dev/null
+++ b/test/perf/passt_vu_tcp
@@ -0,0 +1,211 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# PASST - Plug A Simple Socket Transport
+#  for qemu/UNIX domain socket mode
+#
+# PASTA - Pack A Subtle Tap Abstraction
+#  for network namespace/tap device mode
+#
+# test/perf/passt_vu_tcp - Check TCP performance in passt vhost-user mode
+#
+# Copyright (c) 2021 Red Hat GmbH
+# Author: Stefano Brivio &lt;sbrivio(a)redhat.com&gt;
+
+gtools	/sbin/sysctl ip jq nproc seq sleep iperf3 tcp_rr tcp_crr # From neper
+nstools	/sbin/sysctl ip jq nproc seq sleep iperf3 tcp_rr tcp_crr
+htools	bc head sed seq
+
+set	MAP_NS4 192.0.2.2
+set	MAP_NS6 2001:db8:9a55::2
+
+test	passt: throughput and latency
+
+guest	/sbin/sysctl -w net.core.rmem_max=536870912
+guest	/sbin/sysctl -w net.core.wmem_max=536870912
+guest	/sbin/sysctl -w net.core.rmem_default=33554432
+guest	/sbin/sysctl -w net.core.wmem_default=33554432
+guest	/sbin/sysctl -w net.ipv4.tcp_rmem="4096 131072 268435456"
+guest	/sbin/sysctl -w net.ipv4.tcp_wmem="4096 131072 268435456"
+guest	/sbin/sysctl -w net.ipv4.tcp_timestamps=0
+
+ns	/sbin/sysctl -w net.ipv4.tcp_rmem="4096 524288 134217728"
+ns	/sbin/sysctl -w net.ipv4.tcp_wmem="4096 524288 134217728"
+ns	/sbin/sysctl -w net.ipv4.tcp_timestamps=0
+
+gout	IFNAME ip -j link show | jq -rM '.[] | select(.link_type ==
"ether").ifname'
+
+hout	FREQ_PROCFS (echo "scale=1"; sed -n 's/cpu MHz.*:
\([0-9]*\)\..*$/(\1+10^2\/2)\/10^3/p' /proc/cpuinfo) | bc -l | head -n1
+hout	FREQ_CPUFREQ (echo "scale=1"; printf '( %i + 10^5 / 2 ) /
10^6\n' $(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq) ) | bc -l
+hout	FREQ [ -n "__FREQ_CPUFREQ__" ] && echo __FREQ_CPUFREQ__ || echo
__FREQ_PROCFS__
+
+set	THREADS 4
+set	TIME 5
+set	OMIT 0.1
+set	OPTS -Z -P __THREADS__ -l 1M -O__OMIT__ -N
+
+info	Throughput in Gbps, latency in µs, __THREADS__ threads at __FREQ__ GHz
+report	passt_vu tcp __THREADS__ __FREQ__
+
+th	MTU 256B 576B 1280B 1500B 9000B 65520B
+
+
+tr	TCP throughput over IPv6: guest to host
+iperf3s	ns 10002
+
+bw	-
+bw	-
+guest	ip link set dev __IFNAME__ mtu 1280
+iperf3	BW guest __MAP_NS6__ 10002 __TIME__ __OPTS__ -w 16M
+bw	__BW__ 1.2 1.5
+guest	ip link set dev __IFNAME__ mtu 1500
+iperf3	BW guest __MAP_NS6__ 10002 __TIME__ __OPTS__ -w 32M
+bw	__BW__ 1.6 1.8
+guest	ip link set dev __IFNAME__ mtu 9000
+iperf3	BW guest __MAP_NS6__ 10002 __TIME__ __OPTS__ -w 64M
+bw	__BW__ 4.0 5.0
+guest	ip link set dev __IFNAME__ mtu 65520
+iperf3	BW guest __MAP_NS6__ 10002 __TIME__ __OPTS__ -w 64M
+bw	__BW__ 7.0 8.0
+
+iperf3k	ns
+
+tl	TCP RR latency over IPv6: guest to host
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+nsb	tcp_rr --nolog -6
+gout	LAT tcp_rr --nolog -l1 -6 -c -H __MAP_NS6__ | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 200 150
+
+tl	TCP CRR latency over IPv6: guest to host
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+nsb	tcp_crr --nolog -6
+gout	LAT tcp_crr --nolog -l1 -6 -c -H __MAP_NS6__ | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 500 400
+
+tr	TCP throughput over IPv4: guest to host
+iperf3s	ns 10002
+
+guest	ip link set dev __IFNAME__ mtu 256
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -w 2M
+bw	__BW__ 0.2 0.3
+guest	ip link set dev __IFNAME__ mtu 576
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -w 4M
+bw	__BW__ 0.5 0.8
+guest	ip link set dev __IFNAME__ mtu 1280
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -w 8M
+bw	__BW__ 1.2 1.5
+guest	ip link set dev __IFNAME__ mtu 1500
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -w 16M
+bw	__BW__ 1.6 1.8
+guest	ip link set dev __IFNAME__ mtu 9000
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -w 64M
+bw	__BW__ 4.0 5.0
+guest	ip link set dev __IFNAME__ mtu 65520
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -w 64M
+bw	__BW__ 7.0 8.0
+
+iperf3k	ns
+
+# Reducing MTU below 1280 deconfigures IPv6, get our address back
+guest	dhclient -6 -x
+guest	dhclient -6 __IFNAME__
+
+tl	TCP RR latency over IPv4: guest to host
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+nsb	tcp_rr --nolog -4
+gout	LAT tcp_rr --nolog -l1 -4 -c -H __MAP_NS4__ | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 200 150
+
+tl	TCP CRR latency over IPv4: guest to host
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+nsb	tcp_crr --nolog -4
+gout	LAT tcp_crr --nolog -l1 -4 -c -H __MAP_NS4__ | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 500 400
+
+tr	TCP throughput over IPv6: host to guest
+iperf3s	guest 10001
+
+bw	-
+bw	-
+bw	-
+bw	-
+bw	-
+iperf3	BW ns ::1 10001 __TIME__ __OPTS__ -w 32M
+bw	__BW__ 6.0 6.8
+
+iperf3k	guest
+
+tl	TCP RR latency over IPv6: host to guest
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+guestb	tcp_rr --nolog -P 10001 -C 10011 -6
+sleep	1
+nsout	LAT tcp_rr --nolog -l1 -P 10001 -C 10011 -6 -c -H ::1 | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 200 150
+
+tl	TCP CRR latency over IPv6: host to guest
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+guestb	tcp_crr --nolog -P 10001 -C 10011 -6
+sleep	1
+nsout	LAT tcp_crr --nolog -l1 -P 10001 -C 10011 -6 -c -H ::1 | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 500 350
+
+
+tr	TCP throughput over IPv4: host to guest
+iperf3s	guest 10001
+
+bw	-
+bw	-
+bw	-
+bw	-
+bw	-
+iperf3	BW ns 127.0.0.1 10001 __TIME__ __OPTS__ -w 32M
+bw	__BW__ 6.0 6.8
+
+iperf3k	guest
+
+tl	TCP RR latency over IPv4: host to guest
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+guestb	tcp_rr --nolog -P 10001 -C 10011 -4
+sleep	1
+nsout	LAT tcp_rr --nolog -l1 -P 10001 -C 10011 -4 -c -H 127.0.0.1 | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 200 150
+
+tl	TCP CRR latency over IPv6: host to guest
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+guestb	tcp_crr --nolog -P 10001 -C 10011 -4
+sleep	1
+nsout	LAT tcp_crr --nolog -l1 -P 10001 -C 10011 -4 -c -H 127.0.0.1 | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 500 300
+
+te
diff --git a/test/perf/passt_vu_udp b/test/perf/passt_vu_udp
new file mode 100644
index 000000000000..943ac11b4a51
--- /dev/null
+++ b/test/perf/passt_vu_udp
@@ -0,0 +1,159 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# PASST - Plug A Simple Socket Transport
+#  for qemu/UNIX domain socket mode
+#
+# PASTA - Pack A Subtle Tap Abstraction
+#  for network namespace/tap device mode
+#
+# test/perf/passt_vu_udp - Check UDP performance in passt vhost-user mode
+#
+# Copyright (c) 2021 Red Hat GmbH
+# Author: Stefano Brivio &lt;sbrivio(a)redhat.com&gt;
+
+gtools	/sbin/sysctl ip jq nproc sleep iperf3 udp_rr # From neper
+nstools	ip jq sleep iperf3 udp_rr
+htools	bc head sed
+
+set	MAP_NS4 192.0.2.2
+set	MAP_NS6 2001:db8:9a55::2
+
+test	passt: throughput and latency
+
+guest	/sbin/sysctl -w net.core.rmem_max=16777216
+guest	/sbin/sysctl -w net.core.wmem_max=16777216
+guest	/sbin/sysctl -w net.core.rmem_default=16777216
+guest	/sbin/sysctl -w net.core.wmem_default=16777216
+
+hout	FREQ_PROCFS (echo "scale=1"; sed -n 's/cpu MHz.*:
\([0-9]*\)\..*$/(\1+10^2\/2)\/10^3/p' /proc/cpuinfo) | bc -l | head -n1
+hout	FREQ_CPUFREQ (echo "scale=1"; printf '( %i + 10^5 / 2 ) /
10^6\n' $(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq) ) | bc -l
+hout	FREQ [ -n "__FREQ_CPUFREQ__" ] && echo __FREQ_CPUFREQ__ || echo
__FREQ_PROCFS__
+
+set	THREADS 2
+set	TIME 1
+set	OPTS -u -P __THREADS__ --pacing-timer 1000
+
+info	Throughput in Gbps, latency in µs, __THREADS__ threads at __FREQ__ GHz
+
+report	passt_vu udp __THREADS__ __FREQ__
+
+th	pktlen 256B 576B 1280B 1500B 9000B 65520B
+
+tr	UDP throughput over IPv6: guest to host
+iperf3s	ns 10002
+# (datagram size) = (packet size) - 48: 40 bytes of IPv6 header, 8 of UDP header
+
+bw	-
+bw	-
+iperf3	BW guest __MAP_NS6__ 10002 __TIME__ __OPTS__ -b 3G -l 1232
+bw	__BW__ 0.8 1.2
+iperf3	BW guest __MAP_NS6__ 10002 __TIME__ __OPTS__ -b 4G -l 1452
+bw	__BW__ 1.0 1.5
+iperf3	BW guest __MAP_NS6__ 10002 __TIME__ __OPTS__ -b 10G -l 8952
+bw	__BW__ 4.0 5.0
+iperf3	BW guest __MAP_NS6__ 10002 __TIME__ __OPTS__ -b 20G -l 64372
+bw	__BW__ 4.0 5.0
+
+iperf3k	ns
+
+tl	UDP RR latency over IPv6: guest to host
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+nsb	udp_rr --nolog -6
+gout	LAT udp_rr --nolog -6 -c -H __MAP_NS6__ | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 200 150
+
+
+tr	UDP throughput over IPv4: guest to host
+iperf3s	ns 10002
+# (datagram size) = (packet size) - 28: 20 bytes of IPv4 header, 8 of UDP header
+
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -b 1G -l 228
+bw	__BW__ 0.0 0.0
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -b 2G -l 548
+bw	__BW__ 0.4 0.6
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -b 3G -l 1252
+bw	__BW__ 0.8 1.2
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -b 4G -l 1472
+bw	__BW__ 1.0 1.5
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -b 10G -l 8972
+bw	__BW__ 4.0 5.0
+iperf3	BW guest __MAP_NS4__ 10002 __TIME__ __OPTS__ -b 20G -l 65492
+bw	__BW__ 4.0 5.0
+
+iperf3k	ns
+
+tl	UDP RR latency over IPv4: guest to host
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+nsb	udp_rr --nolog -4
+gout	LAT udp_rr --nolog -4 -c -H __MAP_NS4__ | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 200 150
+
+
+tr	UDP throughput over IPv6: host to guest
+iperf3s	guest 10001
+# (datagram size) = (packet size) - 48: 40 bytes of IPv6 header, 8 of UDP header
+
+bw	-
+bw	-
+iperf3	BW ns ::1 10001 __TIME__ __OPTS__ -b 3G -l 1232
+bw	__BW__ 0.8 1.2
+iperf3	BW ns ::1 10001 __TIME__ __OPTS__ -b 4G -l 1452
+bw	__BW__ 1.0 1.5
+iperf3	BW ns ::1 10001 __TIME__ __OPTS__ -b 10G -l 8952
+bw	__BW__ 3.0 4.0
+iperf3	BW ns ::1 10001 __TIME__ __OPTS__ -b 20G -l 64372
+bw	__BW__ 3.0 4.0
+
+iperf3k	guest
+
+tl	UDP RR latency over IPv6: host to guest
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+guestb	udp_rr --nolog -P 10001 -C 10011 -6
+sleep	1
+nsout	LAT udp_rr --nolog -P 10001 -C 10011 -6 -c -H ::1 | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 200 150
+
+
+tr	UDP throughput over IPv4: host to guest
+iperf3s	guest 10001
+# (datagram size) = (packet size) - 28: 20 bytes of IPv4 header, 8 of UDP header
+
+iperf3	BW ns 127.0.0.1 10001 __TIME__ __OPTS__ -b 1G -l 228
+bw	__BW__ 0.0 0.0
+iperf3	BW ns 127.0.0.1 10001 __TIME__ __OPTS__ -b 2G -l 548
+bw	__BW__ 0.4 0.6
+iperf3	BW ns 127.0.0.1 10001 __TIME__ __OPTS__ -b 3G -l 1252
+bw	__BW__ 0.8 1.2
+iperf3	BW ns 127.0.0.1 10001 __TIME__ __OPTS__ -b 4G -l 1472
+bw	__BW__ 1.0 1.5
+iperf3	BW ns 127.0.0.1 10001 __TIME__ __OPTS__ -b 10G -l 8972
+bw	__BW__ 3.0 4.0
+iperf3	BW ns 127.0.0.1 10001 __TIME__ __OPTS__ -b 20G -l 65492
+bw	__BW__ 3.0 4.0
+
+iperf3k	guest
+
+tl	UDP RR latency over IPv4: host to guest
+lat	-
+lat	-
+lat	-
+lat	-
+lat	-
+guestb	udp_rr --nolog -P 10001 -C 10011 -4
+sleep	1
+nsout	LAT udp_rr --nolog -P 10001 -C 10011 -4 -c -H 127.0.0.1 | sed -n
's/^throughput=\(.*\)/\1/p'
+lat	__LAT__ 200 150
+
+te
diff --git a/test/run b/test/run
index 547a729b3fbe..f188d8eaf2e0 100755
--- a/test/run
+++ b/test/run
@@ -93,6 +93,7 @@ run() {
 	test memory/passt
 	teardown memory
 
+	VHOST_USER=0
 	setup passt
 	test passt/ndp
 	test passt/dhcp
@@ -115,7 +116,22 @@ run() {
 	test two_guests/basic
 	teardown two_guests
 
+	VHOST_USER=1
+	setup passt_in_ns
+	test passt_vu/ndp
+	test passt_vu_in_ns/dhcp
+	test passt_vu_in_ns/icmp
+	test passt_vu_in_ns/tcp
+	test passt_vu_in_ns/udp
+	test passt_vu_in_ns/shutdown
+	teardown passt_in_ns
+
+	setup two_guests
+	test two_guests_vu/basic
+	teardown two_guests
+
 	VALGRIND=0
+	VHOST_USER=0
 	setup passt_in_ns
 	test passt/ndp
 	test passt_in_ns/dhcp
@@ -126,6 +142,15 @@ run() {
 	test passt_in_ns/shutdown
 	teardown passt_in_ns
 
+	VHOST_USER=1
+	setup passt_in_ns
+	test passt_vu/ndp
+	test passt_vu_in_ns/dhcp
+	test perf/passt_vu_tcp
+	test perf/passt_vu_udp
+	test passt_vu_in_ns/shutdown
+	teardown passt_in_ns
+
 	# TODO: Make those faster by at least pre-installing gcc and make on
 	# non-x86 images, then re-enable.
 skip_distro() {
diff --git a/test/two_guests_vu b/test/two_guests_vu
new file mode 120000
index 000000000000..a8648fc7c9fb
--- /dev/null
+++ b/test/two_guests_vu
@@ -0,0 +1 @@
+two_guests
\ No newline at end of file
-- 
2.47.0

On Fri, 22 Nov 2024 17:43:27 +0100
Laurent Vivier <lvivier(a)redhat.com> wrote:

...
  This series of patches adds vhost-user support to
passt
 and then allows passt to connect to QEMU network backend using
 virtqueue rather than a socket. 
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-- 
Stefano