[PATCH v4 3/4] vhost-user: introduce vhost-user API

[Laurent Vivier <lvivier@redhat.com>]

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

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 Makefile     |    4 +-
 iov.c        |    1 -
 vhost_user.c | 1265 ++++++++++++++++++++++++++++++++++++++++++++++++++
 vhost_user.h |  203 ++++++++
 virtio.c     |    5 -
 virtio.h     |    2 +-
 6 files changed, 1471 insertions(+), 9 deletions(-)
 create mode 100644 vhost_user.c
 create mode 100644 vhost_user.h

diff --git a/Makefile b/Makefile
index e9a154bdd718..01e95ac1b62c 100644
--- a/Makefile
+++ b/Makefile
@@ -47,7 +47,7 @@ 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)
 
@@ -57,7 +57,7 @@ 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 <linux/tcp.h>\nstruct tcp_info x = { .tcpi_snd_wnd = 0 };
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/vhost_user.c b/vhost_user.c
new file mode 100644
index 000000000000..6008a8adc967
--- /dev/null
+++ b/vhost_user.c
@@ -0,0 +1,1265 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * vhost-user API, command management and virtio interface
+ *
+ * Copyright Red Hat
+ * Author: Laurent Vivier <lvivier@redhat.com>
+ */
+/* 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 <aliguori@us.ibm.com>
+ *  Marc-André Lureau <mlureau@redhat.com>
+ *  Victor Kaplansky <victork@redhat.com>
+ *
+ * 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"
+
+/* 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: -1 there is an error,
+ *          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 || errno == EAGAIN));
+
+		if (ret < 0)
+			die_perror("vhost-user message receive");
+
+		if (ret < sz_payload)
+			die("EOF 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 || errno == EAGAIN));
+
+	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);
+
+	/* virtio-net features */
+
+	/* VIRTIO_F_VERSION_1 always uses struct virtio_net_hdr_mrg_rxbuf */
+	vdev->hdrlen = sizeof(struct virtio_net_hdr_mrg_rxbuf);
+
+	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_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
+ */
+/* cppcheck-suppress unusedFunction */
+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_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++) {
+		struct vu_dev_region *r = &vdev->regions[i];
+		/* NOLINTNEXTLINE(performance-no-int-to-ptr) */
+		void *mm = (void *)r->mmap_addr;
+
+		if (mm)
+			munmap(mm, 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
+ * @fd:		file descriptor to add
+ */
+static void vu_set_watch(const struct vu_dev *vdev, int fd)
+{
+	/* Placeholder to add passt related code */
+	(void)vdev;
+	(void)fd;
+}
+
+/**
+ * vu_wait_queue() - wait for new free entries in the virtqueue
+ * @vq:		virtqueue to wait on
+ */
+static int vu_wait_queue(const struct vu_virtq *vq)
+{
+	eventfd_t kick_data;
+	ssize_t rc;
+	int status;
+
+	/* wait for the kernel to put new entries in the queue */
+	status = fcntl(vq->kick_fd, F_GETFL);
+	if (status == -1)
+		return -1;
+
+	if (fcntl(vq->kick_fd, F_SETFL, status & ~O_NONBLOCK))
+		return -1;
+
+	rc = eventfd_read(vq->kick_fd, &kick_data);
+
+	if (fcntl(vq->kick_fd, F_SETFL, status))
+		return -1;
+
+	if (rc == -1)
+		return -1;
+
+	return 0;
+}
+
+/**
+ * vu_send() - Send a buffer to the front-end using the RX virtqueue
+ * @vdev:	vhost-user device
+ * @buf:	address of the buffer
+ * @size:	size of the buffer
+ *
+ * Return: number of bytes sent, -1 if there is an error
+ */
+/* cppcheck-suppress unusedFunction */
+int vu_send(struct vu_dev *vdev, const void *buf, size_t size)
+{
+	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 lens[VIRTQUEUE_MAX_SIZE];
+	__virtio16 *num_buffers_ptr = NULL;
+	size_t hdrlen = vdev->hdrlen;
+	int in_sg_count = 0;
+	size_t offset = 0;
+	int i = 0, j;
+
+	debug("vu_send size %zu hdrlen %zu", size, hdrlen);
+
+	if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
+		err("Got packet, but no available descriptors on RX virtq.");
+		return 0;
+	}
+
+	while (offset < size) {
+		size_t len;
+		int total;
+		int ret;
+
+		total = 0;
+
+		if (i == ARRAY_SIZE(elem) ||
+		    in_sg_count == ARRAY_SIZE(in_sg)) {
+			err("virtio-net unexpected long buffer chain");
+			goto err;
+		}
+
+		elem[i].out_num = 0;
+		elem[i].out_sg = NULL;
+		elem[i].in_num = ARRAY_SIZE(in_sg) - in_sg_count;
+		elem[i].in_sg = &in_sg[in_sg_count];
+
+		ret = vu_queue_pop(vdev, vq, &elem[i]);
+		if (ret < 0) {
+			if (vu_wait_queue(vq) != -1)
+				continue;
+			if (i) {
+				err("virtio-net unexpected empty queue: "
+				    "i %d mergeable %d offset %zd, size %zd, "
+				    "features 0x%" PRIx64,
+				    i, vu_has_feature(vdev,
+						      VIRTIO_NET_F_MRG_RXBUF),
+				    offset, size, vdev->features);
+			}
+			offset = -1;
+			goto err;
+		}
+		in_sg_count += elem[i].in_num;
+
+		if (elem[i].in_num < 1) {
+			err("virtio-net receive queue contains no in buffers");
+			vu_queue_detach_element(vq);
+			offset = -1;
+			goto err;
+		}
+
+		if (i == 0) {
+			struct virtio_net_hdr hdr = {
+				.flags = VIRTIO_NET_HDR_F_DATA_VALID,
+				.gso_type = VIRTIO_NET_HDR_GSO_NONE,
+			};
+
+			ASSERT(offset == 0);
+			ASSERT(elem[i].in_sg[0].iov_len >= hdrlen);
+
+			len = iov_from_buf(elem[i].in_sg, elem[i].in_num, 0,
+					   &hdr, sizeof(hdr));
+
+			num_buffers_ptr = (__virtio16 *)((char *)elem[i].in_sg[0].iov_base +
+							 len);
+
+			total += hdrlen;
+		}
+
+		len = iov_from_buf(elem[i].in_sg, elem[i].in_num, total,
+				   (char *)buf + offset, size - offset);
+
+		total += len;
+		offset += len;
+
+		/* If buffers can't be merged, at this point we
+		 * must have consumed the complete packet.
+		 * Otherwise, drop it.
+		 */
+		if (!vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF) &&
+		    offset < size) {
+			vu_queue_unpop(vq);
+			goto err;
+		}
+
+		lens[i] = total;
+		i++;
+	}
+
+	if (num_buffers_ptr && vu_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
+		*num_buffers_ptr = htole16(i);
+
+	for (j = 0; j < i; j++) {
+		debug("filling total %zd idx %d", lens[j], j);
+		vu_queue_fill(vq, &elem[j], lens[j], j);
+	}
+
+	vu_queue_flush(vq, i);
+	vu_queue_notify(vdev, vq);
+
+	debug("vhost-user sent %zu", offset);
+
+	return offset;
+err:
+	for (j = 0; j < i; j++)
+		vu_queue_detach_element(vq);
+
+	return offset;
+}
+
+/**
+ * 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 = vdev->hdrlen;
+	int out_sg_count;
+	int count;
+
+
+	if (!VHOST_USER_IS_QUEUE_TX(index)) {
+		debug("vhost-user: index %d is not a TX queue", index);
+		return;
+	}
+
+	tap_flush_pools();
+
+	count = 0;
+	out_sg_count = 0;
+	while (count < VIRTQUEUE_MAX_SIZE) {
+		int ret;
+
+		elem[count].out_num = 1;
+		elem[count].out_sg = &out_sg[out_sg_count];
+		elem[count].in_num = 0;
+		elem[count].in_sg = 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) {
+			debug("virtio-net header not in first element");
+			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
+ */
+/* cppcheck-suppress unusedFunction */
+void vu_kick_cb(struct vu_dev *vdev, union epoll_ref ref,
+		const struct timespec *now)
+{
+	eventfd_t kick_data;
+	ssize_t rc;
+	int idx;
+
+	for (idx = 0; idx < VHOST_USER_MAX_QUEUES; idx++) {
+		if (vdev->vq[idx].kick_fd == ref.fd)
+			break;
+	}
+
+	if (idx == VHOST_USER_MAX_QUEUES)
+		return;
+
+	rc = eventfd_read(ref.fd, &kick_data);
+	if (rc == -1)
+		die_perror("vhost-user kick eventfd_read()");
+
+	debug("vhost-user: ot kick_data: %016"PRIx64" idx:%d",
+	      kick_data, idx);
+	if (VHOST_USER_IS_QUEUE_TX(idx))
+		vu_handle_tx(vdev, idx, now);
+}
+
+/**
+ * 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 = nofd ? -1 : 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, vdev->vq[idx].kick_fd);
+		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 = nofd ? -1 : 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;
+	}
+
+	/* cppcheck-suppress redundantAssignment */
+	vdev->vq[idx].err_fd = nofd ? -1 : 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;
+
+	if (vu_has_protocol_feature(vdev,
+				    VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS) &&
+	    (!vu_has_protocol_feature(vdev, VHOST_USER_PROTOCOL_F_BACKEND_REQ) ||
+	     !vu_has_protocol_feature(vdev, VHOST_USER_PROTOCOL_F_REPLY_ACK))) {
+	/*
+	 * The use case for using messages for kick/call is simulation, to make
+	 * the kick and call synchronous. To actually get that behaviour, both
+	 * of the other features are required.
+	 * Theoretically, one could use only kick messages, or do them without
+	 * having F_REPLY_ACK, but too many (possibly pending) messages on the
+	 * socket will eventually cause the master to hang, to avoid this in
+	 * scenarios where not desired enforce that the settings are in a way
+	 * that actually enables the simulation case.
+	 */
+		die("F_IN_BAND_NOTIFICATIONS requires F_BACKEND_REQ && F_REPLY_ACK");
+	}
+
+	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;
+	vdev->hdrlen = 0;
+	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;
+	}
+	vdev->hdrlen = 0;
+
+	for (i = 0; i < vdev->nregions; i++) {
+		const struct vu_dev_region *r = &vdev->regions[i];
+		/* NOLINTNEXTLINE(performance-no-int-to-ptr) */
+		void *m = (void *)r->mmap_addr;
+
+		if (m)
+			munmap(m, 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..ed4074c6b915
--- /dev/null
+++ b/vhost_user.h
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * vhost-user API, command management and virtio interface
+ *
+ * Copyright Red Hat
+ * Author: Laurent Vivier <lvivier@redhat.com>
+ */
+
+/* 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))
+
+/**
+ * vu_queue_enabled - Return state of a virtqueue
+ * @vq:		virtqueue to check
+ *
+ * Return: true if the virqueue is enabled, false otherwise
+ */
+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
+ */
+static inline bool vu_queue_started(const struct vu_virtq *vq)
+{
+	return vq->started;
+}
+
+int vu_send(struct vu_dev *vdev, const void *buf, size_t size);
+void vu_print_capabilities(void);
+void vu_init(struct ctx *c, struct vu_dev *vdev);
+void vu_kick_cb(struct vu_dev *vdev, union epoll_ref ref,
+		const struct timespec *now);
+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 380590afbca3..237395396606 100644
--- a/virtio.c
+++ b/virtio.c
@@ -328,7 +328,6 @@ 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 (!vq->vring.avail)
@@ -504,7 +503,6 @@ 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;
@@ -553,7 +551,6 @@ void vu_queue_detach_element(struct vu_virtq *vq)
  * vu_queue_unpop() - Push back the previously popped element from the virqueue
  * @vq:		Virtqueue
  */
-/* cppcheck-suppress unusedFunction */
 void vu_queue_unpop(struct vu_virtq *vq)
 {
 	vq->last_avail_idx--;
@@ -621,7 +618,6 @@ 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)
 {
@@ -645,7 +641,6 @@ 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/virtio.h b/virtio.h
index 0e5705581bd2..d58b9ef7fc1d 100644
--- a/virtio.h
+++ b/virtio.h
@@ -106,6 +106,7 @@ struct vu_dev_region {
  * @hdrlen:		Virtio -net header length
  */
 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];
@@ -162,7 +163,6 @@ static inline bool vu_has_feature(const struct vu_dev *vdev,
  *
  * Return:	True if the feature is available
  */
-/* cppcheck-suppress unusedFunction */
 static inline bool vu_has_protocol_feature(const struct vu_dev *vdev,
 					   unsigned int fbit)
 {
-- 
@@ -106,6 +106,7 @@ struct vu_dev_region {
  * @hdrlen:		Virtio -net header length
  */
 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];
@@ -162,7 +163,6 @@ static inline bool vu_has_feature(const struct vu_dev *vdev,
  *
  * Return:	True if the feature is available
  */
-/* cppcheck-suppress unusedFunction */
 static inline bool vu_has_protocol_feature(const struct vu_dev *vdev,
 					   unsigned int fbit)
 {
-- 
2.46.0