Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging

virtio, vhost, pc: fixes

Here are some bugfixes that didn't make 2.8.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

# gpg: Signature made Fri 16 Dec 2016 21:13:43 GMT
# gpg:                using RSA key 0x281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17  0970 C350 3912 AFBE 8E67
#      Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA  8A0D 281F 0DB8 D28D 5469

* remotes/mst/tags/for_upstream:
  virtio: avoid using guest_notifier_mask in vhost-user mode
  pci: fix error message for express slots
  i386: amd_iommu: fix MMIO register count and access
  tests/vhost-user-bridge: use contrib/libvhost-user
  contrib: add libvhost-user
  tests/vhost-user-bridge: do not accept more than one connection
  tests/vhost-user-bridge: indicate peer disconnected
  tests/vhost-user-bridge: remove unnecessary dispatcher_remove
  tests/vhost-user-bridge: remove false comment

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

12 files changed, 2175 insertions, 964 deletions

diff --git a/Makefile b/Makefile
index 214cbad..1a8bfb2 100644
--- a/Makefile
+++ b/Makefile
@@ -149,6 +149,7 @@ dummy := $(call unnest-vars,, \
                 qga-obj-y \
                 ivshmem-client-obj-y \
                 ivshmem-server-obj-y \
+                libvhost-user-obj-y \
                 qga-vss-dll-obj-y \
                 block-obj-y \
                 block-obj-m \
diff --git a/Makefile.objs b/Makefile.objs
index 51c36a4..01cef86 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -115,7 +115,7 @@ qga-vss-dll-obj-y = qga/
 # contrib
 ivshmem-client-obj-y = contrib/ivshmem-client/
 ivshmem-server-obj-y = contrib/ivshmem-server/
-
+libvhost-user-obj-y = contrib/libvhost-user/
 
 ######################################################################
 trace-events-y = trace-events
diff --git a/contrib/libvhost-user/Makefile.objs b/contrib/libvhost-user/Makefile.objs
new file mode 100644
index 0000000..cef1ad6
--- /dev/null
+++ b/contrib/libvhost-user/Makefile.objs
@@ -0,0 +1 @@
+libvhost-user-obj-y = libvhost-user.o
diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
new file mode 100644
index 0000000..af4faad
--- /dev/null
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -0,0 +1,1499 @@
+/*
+ * Vhost User library
+ *
+ * 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 <qemu/osdep.h>
+#include <sys/eventfd.h>
+#include <linux/vhost.h>
+
+#include "qemu/atomic.h"
+
+#include "libvhost-user.h"
+
+#define VHOST_USER_HDR_SIZE offsetof(VhostUserMsg, payload.u64)
+
+/* The version of the protocol we support */
+#define VHOST_USER_VERSION 1
+#define LIBVHOST_USER_DEBUG 0
+
+#define DPRINT(...)                             \
+    do {                                        \
+        if (LIBVHOST_USER_DEBUG) {              \
+            fprintf(stderr, __VA_ARGS__);        \
+        }                                       \
+    } while (0)
+
+static const char *
+vu_request_to_string(int req)
+{
+#define REQ(req) [req] = #req
+    static const char *vu_request_str[] = {
+        REQ(VHOST_USER_NONE),
+        REQ(VHOST_USER_GET_FEATURES),
+        REQ(VHOST_USER_SET_FEATURES),
+        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_INPUT_GET_CONFIG),
+        REQ(VHOST_USER_MAX),
+    };
+#undef REQ
+
+    if (req < VHOST_USER_MAX) {
+        return vu_request_str[req];
+    } else {
+        return "unknown";
+    }
+}
+
+static void
+vu_panic(VuDev *dev, const char *msg, ...)
+{
+    char *buf = NULL;
+    va_list ap;
+
+    va_start(ap, msg);
+    (void)vasprintf(&buf, msg, ap);
+    va_end(ap);
+
+    dev->broken = true;
+    dev->panic(dev, buf);
+    free(buf);
+
+    /* FIXME: find a way to call virtio_error? */
+}
+
+/* Translate guest physical address to our virtual address.  */
+void *
+vu_gpa_to_va(VuDev *dev, uint64_t guest_addr)
+{
+    int i;
+
+    /* Find matching memory region.  */
+    for (i = 0; i < dev->nregions; i++) {
+        VuDevRegion *r = &dev->regions[i];
+
+        if ((guest_addr >= r->gpa) && (guest_addr < (r->gpa + r->size))) {
+            return (void *)(uintptr_t)
+                guest_addr - r->gpa + r->mmap_addr + r->mmap_offset;
+        }
+    }
+
+    return NULL;
+}
+
+/* Translate qemu virtual address to our virtual address.  */
+static void *
+qva_to_va(VuDev *dev, uint64_t qemu_addr)
+{
+    int i;
+
+    /* Find matching memory region.  */
+    for (i = 0; i < dev->nregions; i++) {
+        VuDevRegion *r = &dev->regions[i];
+
+        if ((qemu_addr >= r->qva) && (qemu_addr < (r->qva + r->size))) {
+            return (void *)(uintptr_t)
+                qemu_addr - r->qva + r->mmap_addr + r->mmap_offset;
+        }
+    }
+
+    return NULL;
+}
+
+static void
+vmsg_close_fds(VhostUserMsg *vmsg)
+{
+    int i;
+
+    for (i = 0; i < vmsg->fd_num; i++) {
+        close(vmsg->fds[i]);
+    }
+}
+
+static bool
+vu_message_read(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
+{
+    char control[CMSG_SPACE(VHOST_MEMORY_MAX_NREGIONS * sizeof(int))] = { };
+    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),
+    };
+    size_t fd_size;
+    struct cmsghdr *cmsg;
+    int rc;
+
+    do {
+        rc = recvmsg(conn_fd, &msg, 0);
+    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+
+    if (rc <= 0) {
+        vu_panic(dev, "Error while recvmsg: %s", strerror(errno));
+        return false;
+    }
+
+    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) {
+            fd_size = cmsg->cmsg_len - CMSG_LEN(0);
+            vmsg->fd_num = fd_size / sizeof(int);
+            memcpy(vmsg->fds, CMSG_DATA(cmsg), fd_size);
+            break;
+        }
+    }
+
+    if (vmsg->size > sizeof(vmsg->payload)) {
+        vu_panic(dev,
+                 "Error: too big message request: %d, size: vmsg->size: %u, "
+                 "while sizeof(vmsg->payload) = %zu\n",
+                 vmsg->request, vmsg->size, sizeof(vmsg->payload));
+        goto fail;
+    }
+
+    if (vmsg->size) {
+        do {
+            rc = read(conn_fd, &vmsg->payload, vmsg->size);
+        } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+
+        if (rc <= 0) {
+            vu_panic(dev, "Error while reading: %s", strerror(errno));
+            goto fail;
+        }
+
+        assert(rc == vmsg->size);
+    }
+
+    return true;
+
+fail:
+    vmsg_close_fds(vmsg);
+
+    return false;
+}
+
+static bool
+vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
+{
+    int rc;
+    uint8_t *p = (uint8_t *)vmsg;
+
+    /* Set the version in the flags when sending the reply */
+    vmsg->flags &= ~VHOST_USER_VERSION_MASK;
+    vmsg->flags |= VHOST_USER_VERSION;
+    vmsg->flags |= VHOST_USER_REPLY_MASK;
+
+    do {
+        rc = write(conn_fd, p, VHOST_USER_HDR_SIZE);
+    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+
+    do {
+        if (vmsg->data) {
+            rc = write(conn_fd, vmsg->data, vmsg->size);
+        } else {
+            rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size);
+        }
+    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+
+    if (rc <= 0) {
+        vu_panic(dev, "Error while writing: %s", strerror(errno));
+        return false;
+    }
+
+    return true;
+}
+
+/* Kick the log_call_fd if required. */
+static void
+vu_log_kick(VuDev *dev)
+{
+    if (dev->log_call_fd != -1) {
+        DPRINT("Kicking the QEMU's log...\n");
+        if (eventfd_write(dev->log_call_fd, 1) < 0) {
+            vu_panic(dev, "Error writing eventfd: %s", strerror(errno));
+        }
+    }
+}
+
+static void
+vu_log_page(uint8_t *log_table, uint64_t page)
+{
+    DPRINT("Logged dirty guest page: %"PRId64"\n", page);
+    atomic_or(&log_table[page / 8], 1 << (page % 8));
+}
+
+static void
+vu_log_write(VuDev *dev, uint64_t address, uint64_t length)
+{
+    uint64_t page;
+
+    if (!(dev->features & (1ULL << VHOST_F_LOG_ALL)) ||
+        !dev->log_table || !length) {
+        return;
+    }
+
+    assert(dev->log_size > ((address + length - 1) / VHOST_LOG_PAGE / 8));
+
+    page = address / VHOST_LOG_PAGE;
+    while (page * VHOST_LOG_PAGE < address + length) {
+        vu_log_page(dev->log_table, page);
+        page += VHOST_LOG_PAGE;
+    }
+
+    vu_log_kick(dev);
+}
+
+static void
+vu_kick_cb(VuDev *dev, int condition, void *data)
+{
+    int index = (intptr_t)data;
+    VuVirtq *vq = &dev->vq[index];
+    int sock = vq->kick_fd;
+    eventfd_t kick_data;
+    ssize_t rc;
+
+    rc = eventfd_read(sock, &kick_data);
+    if (rc == -1) {
+        vu_panic(dev, "kick eventfd_read(): %s", strerror(errno));
+        dev->remove_watch(dev, dev->vq[index].kick_fd);
+    } else {
+        DPRINT("Got kick_data: %016"PRIx64" handler:%p idx:%d\n",
+               kick_data, vq->handler, index);
+        if (vq->handler) {
+            vq->handler(dev, index);
+        }
+    }
+}
+
+static bool
+vu_get_features_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    vmsg->payload.u64 =
+        1ULL << VHOST_F_LOG_ALL |
+        1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
+
+    if (dev->iface->get_features) {
+        vmsg->payload.u64 |= dev->iface->get_features(dev);
+    }
+
+    vmsg->size = sizeof(vmsg->payload.u64);
+
+    DPRINT("Sending back to guest u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
+
+    return true;
+}
+
+static void
+vu_set_enable_all_rings(VuDev *dev, bool enabled)
+{
+    int i;
+
+    for (i = 0; i < VHOST_MAX_NR_VIRTQUEUE; i++) {
+        dev->vq[i].enable = enabled;
+    }
+}
+
+static bool
+vu_set_features_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
+
+    dev->features = vmsg->payload.u64;
+
+    if (!(dev->features & VHOST_USER_F_PROTOCOL_FEATURES)) {
+        vu_set_enable_all_rings(dev, true);
+    }
+
+    if (dev->iface->set_features) {
+        dev->iface->set_features(dev, dev->features);
+    }
+
+    return false;
+}
+
+static bool
+vu_set_owner_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    return false;
+}
+
+static void
+vu_close_log(VuDev *dev)
+{
+    if (dev->log_table) {
+        if (munmap(dev->log_table, dev->log_size) != 0) {
+            perror("close log munmap() error");
+        }
+
+        dev->log_table = NULL;
+    }
+    if (dev->log_call_fd != -1) {
+        close(dev->log_call_fd);
+        dev->log_call_fd = -1;
+    }
+}
+
+static bool
+vu_reset_device_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    vu_set_enable_all_rings(dev, false);
+
+    return false;
+}
+
+static bool
+vu_set_mem_table_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    int i;
+    VhostUserMemory *memory = &vmsg->payload.memory;
+    dev->nregions = memory->nregions;
+
+    DPRINT("Nregions: %d\n", memory->nregions);
+    for (i = 0; i < dev->nregions; i++) {
+        void *mmap_addr;
+        VhostUserMemoryRegion *msg_region = &memory->regions[i];
+        VuDevRegion *dev_region = &dev->regions[i];
+
+        DPRINT("Region %d\n", i);
+        DPRINT("    guest_phys_addr: 0x%016"PRIx64"\n",
+               msg_region->guest_phys_addr);
+        DPRINT("    memory_size:     0x%016"PRIx64"\n",
+               msg_region->memory_size);
+        DPRINT("    userspace_addr   0x%016"PRIx64"\n",
+               msg_region->userspace_addr);
+        DPRINT("    mmap_offset      0x%016"PRIx64"\n",
+               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, and we use huge
+         * pages.  */
+        mmap_addr = mmap(0, dev_region->size + dev_region->mmap_offset,
+                         PROT_READ | PROT_WRITE, MAP_SHARED,
+                         vmsg->fds[i], 0);
+
+        if (mmap_addr == MAP_FAILED) {
+            vu_panic(dev, "region mmap error: %s", strerror(errno));
+        } else {
+            dev_region->mmap_addr = (uint64_t)(uintptr_t)mmap_addr;
+            DPRINT("    mmap_addr:       0x%016"PRIx64"\n",
+                   dev_region->mmap_addr);
+        }
+
+        close(vmsg->fds[i]);
+    }
+
+    return false;
+}
+
+static bool
+vu_set_log_base_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    int fd;
+    uint64_t log_mmap_size, log_mmap_offset;
+    void *rc;
+
+    if (vmsg->fd_num != 1 ||
+        vmsg->size != sizeof(vmsg->payload.log)) {
+        vu_panic(dev, "Invalid log_base message");
+        return true;
+    }
+
+    fd = vmsg->fds[0];
+    log_mmap_offset = vmsg->payload.log.mmap_offset;
+    log_mmap_size = vmsg->payload.log.mmap_size;
+    DPRINT("Log mmap_offset: %"PRId64"\n", log_mmap_offset);
+    DPRINT("Log mmap_size:   %"PRId64"\n", log_mmap_size);
+
+    rc = mmap(0, log_mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
+              log_mmap_offset);
+    if (rc == MAP_FAILED) {
+        perror("log mmap error");
+    }
+    dev->log_table = rc;
+    dev->log_size = log_mmap_size;
+
+    vmsg->size = sizeof(vmsg->payload.u64);
+
+    return true;
+}
+
+static bool
+vu_set_log_fd_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    if (vmsg->fd_num != 1) {
+        vu_panic(dev, "Invalid log_fd message");
+        return false;
+    }
+
+    if (dev->log_call_fd != -1) {
+        close(dev->log_call_fd);
+    }
+    dev->log_call_fd = vmsg->fds[0];
+    DPRINT("Got log_call_fd: %d\n", vmsg->fds[0]);
+
+    return false;
+}
+
+static bool
+vu_set_vring_num_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    unsigned int index = vmsg->payload.state.index;
+    unsigned int num = vmsg->payload.state.num;
+
+    DPRINT("State.index: %d\n", index);
+    DPRINT("State.num:   %d\n", num);
+    dev->vq[index].vring.num = num;
+
+    return false;
+}
+
+static bool
+vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    struct vhost_vring_addr *vra = &vmsg->payload.addr;
+    unsigned int index = vra->index;
+    VuVirtq *vq = &dev->vq[index];
+
+    DPRINT("vhost_vring_addr:\n");
+    DPRINT("    index:  %d\n", vra->index);
+    DPRINT("    flags:  %d\n", vra->flags);
+    DPRINT("    desc_user_addr:   0x%016llx\n", vra->desc_user_addr);
+    DPRINT("    used_user_addr:   0x%016llx\n", vra->used_user_addr);
+    DPRINT("    avail_user_addr:  0x%016llx\n", vra->avail_user_addr);
+    DPRINT("    log_guest_addr:   0x%016llx\n", vra->log_guest_addr);
+
+    vq->vring.flags = vra->flags;
+    vq->vring.desc = qva_to_va(dev, vra->desc_user_addr);
+    vq->vring.used = qva_to_va(dev, vra->used_user_addr);
+    vq->vring.avail = qva_to_va(dev, vra->avail_user_addr);
+    vq->vring.log_guest_addr = vra->log_guest_addr;
+
+    DPRINT("Setting virtq addresses:\n");
+    DPRINT("    vring_desc  at %p\n", vq->vring.desc);
+    DPRINT("    vring_used  at %p\n", vq->vring.used);
+    DPRINT("    vring_avail at %p\n", vq->vring.avail);
+
+    if (!(vq->vring.desc && vq->vring.used && vq->vring.avail)) {
+        vu_panic(dev, "Invalid vring_addr message");
+        return false;
+    }
+
+    vq->used_idx = vq->vring.used->idx;
+
+    return false;
+}
+
+static bool
+vu_set_vring_base_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    unsigned int index = vmsg->payload.state.index;
+    unsigned int num = vmsg->payload.state.num;
+
+    DPRINT("State.index: %d\n", index);
+    DPRINT("State.num:   %d\n", num);
+    dev->vq[index].shadow_avail_idx = dev->vq[index].last_avail_idx = num;
+
+    return false;
+}
+
+static bool
+vu_get_vring_base_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    unsigned int index = vmsg->payload.state.index;
+
+    DPRINT("State.index: %d\n", index);
+    vmsg->payload.state.num = dev->vq[index].last_avail_idx;
+    vmsg->size = sizeof(vmsg->payload.state);
+
+    dev->vq[index].started = false;
+    if (dev->iface->queue_set_started) {
+        dev->iface->queue_set_started(dev, index, false);
+    }
+
+    if (dev->vq[index].call_fd != -1) {
+        close(dev->vq[index].call_fd);
+        dev->vq[index].call_fd = -1;
+    }
+    if (dev->vq[index].kick_fd != -1) {
+        dev->remove_watch(dev, dev->vq[index].kick_fd);
+        close(dev->vq[index].kick_fd);
+        dev->vq[index].kick_fd = -1;
+    }
+
+    return true;
+}
+
+static bool
+vu_check_queue_msg_file(VuDev *dev, VhostUserMsg *vmsg)
+{
+    int index = vmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+
+    if (index >= VHOST_MAX_NR_VIRTQUEUE) {
+        vmsg_close_fds(vmsg);
+        vu_panic(dev, "Invalid queue index: %u", index);
+        return false;
+    }
+
+    if (vmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK ||
+        vmsg->fd_num != 1) {
+        vmsg_close_fds(vmsg);
+        vu_panic(dev, "Invalid fds in request: %d", vmsg->request);
+        return false;
+    }
+
+    return true;
+}
+
+static bool
+vu_set_vring_kick_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    int index = vmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+
+    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
+
+    if (!vu_check_queue_msg_file(dev, vmsg)) {
+        return false;
+    }
+
+    if (dev->vq[index].kick_fd != -1) {
+        dev->remove_watch(dev, dev->vq[index].kick_fd);
+        close(dev->vq[index].kick_fd);
+        dev->vq[index].kick_fd = -1;
+    }
+
+    if (!(vmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)) {
+        dev->vq[index].kick_fd = vmsg->fds[0];
+        DPRINT("Got kick_fd: %d for vq: %d\n", vmsg->fds[0], index);
+    }
+
+    dev->vq[index].started = true;
+    if (dev->iface->queue_set_started) {
+        dev->iface->queue_set_started(dev, index, true);
+    }
+
+    if (dev->vq[index].kick_fd != -1 && dev->vq[index].handler) {
+        dev->set_watch(dev, dev->vq[index].kick_fd, VU_WATCH_IN,
+                       vu_kick_cb, (void *)(long)index);
+
+        DPRINT("Waiting for kicks on fd: %d for vq: %d\n",
+               dev->vq[index].kick_fd, index);
+    }
+
+    return false;
+}
+
+void vu_set_queue_handler(VuDev *dev, VuVirtq *vq,
+                          vu_queue_handler_cb handler)
+{
+    int qidx = vq - dev->vq;
+
+    vq->handler = handler;
+    if (vq->kick_fd >= 0) {
+        if (handler) {
+            dev->set_watch(dev, vq->kick_fd, VU_WATCH_IN,
+                           vu_kick_cb, (void *)(long)qidx);
+        } else {
+            dev->remove_watch(dev, vq->kick_fd);
+        }
+    }
+}
+
+static bool
+vu_set_vring_call_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    int index = vmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+
+    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
+
+    if (!vu_check_queue_msg_file(dev, vmsg)) {
+        return false;
+    }
+
+    if (dev->vq[index].call_fd != -1) {
+        close(dev->vq[index].call_fd);
+        dev->vq[index].call_fd = -1;
+    }
+
+    if (!(vmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)) {
+        dev->vq[index].call_fd = vmsg->fds[0];
+    }
+
+    DPRINT("Got call_fd: %d for vq: %d\n", vmsg->fds[0], index);
+
+    return false;
+}
+
+static bool
+vu_set_vring_err_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    int index = vmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+
+    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
+
+    if (!vu_check_queue_msg_file(dev, vmsg)) {
+        return false;
+    }
+
+    if (dev->vq[index].err_fd != -1) {
+        close(dev->vq[index].err_fd);
+        dev->vq[index].err_fd = -1;
+    }
+
+    if (!(vmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)) {
+        dev->vq[index].err_fd = vmsg->fds[0];
+    }
+
+    return false;
+}
+
+static bool
+vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD;
+
+    if (dev->iface->get_protocol_features) {
+        features |= dev->iface->get_protocol_features(dev);
+    }
+
+    vmsg->payload.u64 = features;
+    vmsg->size = sizeof(vmsg->payload.u64);
+
+    return true;
+}
+
+static bool
+vu_set_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    uint64_t features = vmsg->payload.u64;
+
+    DPRINT("u64: 0x%016"PRIx64"\n", features);
+
+    dev->protocol_features = vmsg->payload.u64;
+
+    if (dev->iface->set_protocol_features) {
+        dev->iface->set_protocol_features(dev, features);
+    }
+
+    return false;
+}
+
+static bool
+vu_get_queue_num_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    DPRINT("Function %s() not implemented yet.\n", __func__);
+    return false;
+}
+
+static bool
+vu_set_vring_enable_exec(VuDev *dev, VhostUserMsg *vmsg)
+{
+    unsigned int index = vmsg->payload.state.index;
+    unsigned int enable = vmsg->payload.state.num;
+
+    DPRINT("State.index: %d\n", index);
+    DPRINT("State.enable:   %d\n", enable);
+
+    if (index >= VHOST_MAX_NR_VIRTQUEUE) {
+        vu_panic(dev, "Invalid vring_enable index: %u", index);
+        return false;
+    }
+
+    dev->vq[index].enable = enable;
+    return false;
+}
+
+static bool
+vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
+{
+    int do_reply = 0;
+
+    /* Print out generic part of the request. */
+    DPRINT("================ Vhost user message ================\n");
+    DPRINT("Request: %s (%d)\n", vu_request_to_string(vmsg->request),
+           vmsg->request);
+    DPRINT("Flags:   0x%x\n", vmsg->flags);
+    DPRINT("Size:    %d\n", vmsg->size);
+
+    if (vmsg->fd_num) {
+        int i;
+        DPRINT("Fds:");
+        for (i = 0; i < vmsg->fd_num; i++) {
+            DPRINT(" %d", vmsg->fds[i]);
+        }
+        DPRINT("\n");
+    }
+
+    if (dev->iface->process_msg &&
+        dev->iface->process_msg(dev, vmsg, &do_reply)) {
+        return do_reply;
+    }
+
+    switch (vmsg->request) {
+    case VHOST_USER_GET_FEATURES:
+        return vu_get_features_exec(dev, vmsg);
+    case VHOST_USER_SET_FEATURES:
+        return vu_set_features_exec(dev, vmsg);
+    case VHOST_USER_GET_PROTOCOL_FEATURES:
+        return vu_get_protocol_features_exec(dev, vmsg);
+    case VHOST_USER_SET_PROTOCOL_FEATURES:
+        return vu_set_protocol_features_exec(dev, vmsg);
+    case VHOST_USER_SET_OWNER:
+        return vu_set_owner_exec(dev, vmsg);
+    case VHOST_USER_RESET_OWNER:
+        return vu_reset_device_exec(dev, vmsg);
+    case VHOST_USER_SET_MEM_TABLE:
+        return vu_set_mem_table_exec(dev, vmsg);
+    case VHOST_USER_SET_LOG_BASE:
+        return vu_set_log_base_exec(dev, vmsg);
+    case VHOST_USER_SET_LOG_FD:
+        return vu_set_log_fd_exec(dev, vmsg);
+    case VHOST_USER_SET_VRING_NUM:
+        return vu_set_vring_num_exec(dev, vmsg);
+    case VHOST_USER_SET_VRING_ADDR:
+        return vu_set_vring_addr_exec(dev, vmsg);
+    case VHOST_USER_SET_VRING_BASE:
+        return vu_set_vring_base_exec(dev, vmsg);
+    case VHOST_USER_GET_VRING_BASE:
+        return vu_get_vring_base_exec(dev, vmsg);
+    case VHOST_USER_SET_VRING_KICK:
+        return vu_set_vring_kick_exec(dev, vmsg);
+    case VHOST_USER_SET_VRING_CALL:
+        return vu_set_vring_call_exec(dev, vmsg);
+    case VHOST_USER_SET_VRING_ERR:
+        return vu_set_vring_err_exec(dev, vmsg);
+    case VHOST_USER_GET_QUEUE_NUM:
+        return vu_get_queue_num_exec(dev, vmsg);
+    case VHOST_USER_SET_VRING_ENABLE:
+        return vu_set_vring_enable_exec(dev, vmsg);
+    default:
+        vmsg_close_fds(vmsg);
+        vu_panic(dev, "Unhandled request: %d", vmsg->request);
+    }
+
+    return false;
+}
+
+bool
+vu_dispatch(VuDev *dev)
+{
+    VhostUserMsg vmsg = { 0, };
+    int reply_requested;
+    bool success = false;
+
+    if (!vu_message_read(dev, dev->sock, &vmsg)) {
+        goto end;
+    }
+
+    reply_requested = vu_process_message(dev, &vmsg);
+    if (!reply_requested) {
+        success = true;
+        goto end;
+    }
+
+    if (!vu_message_write(dev, dev->sock, &vmsg)) {
+        goto end;
+    }
+
+    success = true;
+
+end:
+    g_free(vmsg.data);
+    return success;
+}
+
+void
+vu_deinit(VuDev *dev)
+{
+    int i;
+
+    for (i = 0; i < dev->nregions; i++) {
+        VuDevRegion *r = &dev->regions[i];
+        void *m = (void *) (uintptr_t) r->mmap_addr;
+        if (m != MAP_FAILED) {
+            munmap(m, r->size + r->mmap_offset);
+        }
+    }
+    dev->nregions = 0;
+
+    for (i = 0; i < VHOST_MAX_NR_VIRTQUEUE; i++) {
+        VuVirtq *vq = &dev->vq[i];
+
+        if (vq->call_fd != -1) {
+            close(vq->call_fd);
+            vq->call_fd = -1;
+        }
+
+        if (vq->kick_fd != -1) {
+            close(vq->kick_fd);
+            vq->kick_fd = -1;
+        }
+
+        if (vq->err_fd != -1) {
+            close(vq->err_fd);
+            vq->err_fd = -1;
+        }
+    }
+
+
+    vu_close_log(dev);
+
+    if (dev->sock != -1) {
+        close(dev->sock);
+    }
+}
+
+void
+vu_init(VuDev *dev,
+        int socket,
+        vu_panic_cb panic,
+        vu_set_watch_cb set_watch,
+        vu_remove_watch_cb remove_watch,
+        const VuDevIface *iface)
+{
+    int i;
+
+    assert(socket >= 0);
+    assert(set_watch);
+    assert(remove_watch);
+    assert(iface);
+    assert(panic);
+
+    memset(dev, 0, sizeof(*dev));
+
+    dev->sock = socket;
+    dev->panic = panic;
+    dev->set_watch = set_watch;
+    dev->remove_watch = remove_watch;
+    dev->iface = iface;
+    dev->log_call_fd = -1;
+    for (i = 0; i < VHOST_MAX_NR_VIRTQUEUE; i++) {
+        dev->vq[i] = (VuVirtq) {
+            .call_fd = -1, .kick_fd = -1, .err_fd = -1,
+            .notification = true,
+        };
+    }
+}
+
+VuVirtq *
+vu_get_queue(VuDev *dev, int qidx)
+{
+    assert(qidx < VHOST_MAX_NR_VIRTQUEUE);
+    return &dev->vq[qidx];
+}
+
+bool
+vu_queue_enabled(VuDev *dev, VuVirtq *vq)
+{
+    return vq->enable;
+}
+
+static inline uint16_t
+vring_avail_flags(VuVirtq *vq)
+{
+    return vq->vring.avail->flags;
+}
+
+static inline uint16_t
+vring_avail_idx(VuVirtq *vq)
+{
+    vq->shadow_avail_idx = vq->vring.avail->idx;
+
+    return vq->shadow_avail_idx;
+}
+
+static inline uint16_t
+vring_avail_ring(VuVirtq *vq, int i)
+{
+    return vq->vring.avail->ring[i];
+}
+
+static inline uint16_t
+vring_get_used_event(VuVirtq *vq)
+{
+    return vring_avail_ring(vq, vq->vring.num);
+}
+
+static int
+virtqueue_num_heads(VuDev *dev, VuVirtq *vq, unsigned int idx)
+{
+    uint16_t num_heads = vring_avail_idx(vq) - idx;
+
+    /* Check it isn't doing very strange things with descriptor numbers. */
+    if (num_heads > vq->vring.num) {
+        vu_panic(dev, "Guest moved used index from %u to %u",
+                 idx, vq->shadow_avail_idx);
+        return -1;
+    }
+    if (num_heads) {
+        /* On success, callers read a descriptor at vq->last_avail_idx.
+         * Make sure descriptor read does not bypass avail index read. */
+        smp_rmb();
+    }
+
+    return num_heads;
+}
+
+static bool
+virtqueue_get_head(VuDev *dev, VuVirtq *vq,
+                   unsigned int idx, unsigned int *head)
+{
+    /* Grab the next descriptor number they're advertising, and increment
+     * the index we've seen. */
+    *head = vring_avail_ring(vq, idx % vq->vring.num);
+
+    /* If their number is silly, that's a fatal mistake. */
+    if (*head >= vq->vring.num) {
+        vu_panic(dev, "Guest says index %u is available", head);
+        return false;
+    }
+
+    return true;
+}
+
+enum {
+    VIRTQUEUE_READ_DESC_ERROR = -1,
+    VIRTQUEUE_READ_DESC_DONE = 0,   /* end of chain */
+    VIRTQUEUE_READ_DESC_MORE = 1,   /* more buffers in chain */
+};
+
+static int
+virtqueue_read_next_desc(VuDev *dev, struct vring_desc *desc,
+                         int i, unsigned int max, unsigned int *next)
+{
+    /* If this descriptor says it doesn't chain, we're done. */
+    if (!(desc[i].flags & VRING_DESC_F_NEXT)) {
+        return VIRTQUEUE_READ_DESC_DONE;
+    }
+
+    /* Check they're not leading us off end of descriptors. */
+    *next = desc[i].next;
+    /* Make sure compiler knows to grab that: we don't want it changing! */
+    smp_wmb();
+
+    if (*next >= max) {
+        vu_panic(dev, "Desc next is %u", next);
+        return VIRTQUEUE_READ_DESC_ERROR;
+    }
+
+    return VIRTQUEUE_READ_DESC_MORE;
+}
+
+void
+vu_queue_get_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int *in_bytes,
+                         unsigned int *out_bytes,
+                         unsigned max_in_bytes, unsigned max_out_bytes)
+{
+    unsigned int idx;
+    unsigned int total_bufs, in_total, out_total;
+    int rc;
+
+    idx = vq->last_avail_idx;
+
+    total_bufs = in_total = out_total = 0;
+    while ((rc = virtqueue_num_heads(dev, vq, idx)) > 0) {
+        unsigned int max, num_bufs, indirect = 0;
+        struct vring_desc *desc;
+        unsigned int i;
+
+        max = vq->vring.num;
+        num_bufs = total_bufs;
+        if (!virtqueue_get_head(dev, vq, idx++, &i)) {
+            goto err;
+        }
+        desc = vq->vring.desc;
+
+        if (desc[i].flags & VRING_DESC_F_INDIRECT) {
+            if (desc[i].len % sizeof(struct vring_desc)) {
+                vu_panic(dev, "Invalid size for indirect buffer table");
+                goto err;
+            }
+
+            /* If we've got too many, that implies a descriptor loop. */
+            if (num_bufs >= max) {
+                vu_panic(dev, "Looped descriptor");
+                goto err;
+            }
+
+            /* loop over the indirect descriptor table */
+            indirect = 1;
+            max = desc[i].len / sizeof(struct vring_desc);
+            desc = vu_gpa_to_va(dev, desc[i].addr);
+            num_bufs = i = 0;
+        }
+
+        do {
+            /* If we've got too many, that implies a descriptor loop. */
+            if (++num_bufs > max) {
+                vu_panic(dev, "Looped descriptor");
+                goto err;
+            }
+
+            if (desc[i].flags & VRING_DESC_F_WRITE) {
+                in_total += desc[i].len;
+            } else {
+                out_total += desc[i].len;
+            }
+            if (in_total >= max_in_bytes && out_total >= max_out_bytes) {
+                goto done;
+            }
+            rc = virtqueue_read_next_desc(dev, desc, i, max, &i);
+        } while (rc == VIRTQUEUE_READ_DESC_MORE);
+
+        if (rc == VIRTQUEUE_READ_DESC_ERROR) {
+            goto err;
+        }
+
+        if (!indirect) {
+            total_bufs = num_bufs;
+        } else {
+            total_bufs++;
+        }
+    }
+    if (rc < 0) {
+        goto err;
+    }
+done:
+    if (in_bytes) {
+        *in_bytes = in_total;
+    }
+    if (out_bytes) {
+        *out_bytes = out_total;
+    }
+    return;
+
+err:
+    in_total = out_total = 0;
+    goto done;
+}
+
+bool
+vu_queue_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int in_bytes,
+                     unsigned int out_bytes)
+{
+    unsigned int in_total, out_total;
+
+    vu_queue_get_avail_bytes(dev, vq, &in_total, &out_total,
+                             in_bytes, out_bytes);
+
+    return in_bytes <= in_total && out_bytes <= out_total;
+}
+
+/* Fetch avail_idx from VQ memory only when we really need to know if
+ * guest has added some buffers. */
+int
+vu_queue_empty(VuDev *dev, VuVirtq *vq)
+{
+    if (vq->shadow_avail_idx != vq->last_avail_idx) {
+        return 0;
+    }
+
+    return vring_avail_idx(vq) == vq->last_avail_idx;
+}
+
+static inline
+bool has_feature(uint64_t features, unsigned int fbit)
+{
+    assert(fbit < 64);
+    return !!(features & (1ULL << fbit));
+}
+
+static inline
+bool vu_has_feature(VuDev *dev,
+                    unsigned int fbit)
+{
+    return has_feature(dev->features, fbit);
+}
+
+static bool
+vring_notify(VuDev *dev, VuVirtq *vq)
+{
+    uint16_t old, new;
+    bool v;
+
+    /* We need to expose used array entries before checking used event. */
+    smp_mb();
+
+    /* Always notify when queue is empty (when feature acknowledge) */
+    if (vu_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
+        !vq->inuse && vu_queue_empty(dev, vq)) {
+        return true;
+    }
+
+    if (!vu_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
+        return !(vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT);
+    }
+
+    v = vq->signalled_used_valid;
+    vq->signalled_used_valid = true;
+    old = vq->signalled_used;
+    new = vq->signalled_used = vq->used_idx;
+    return !v || vring_need_event(vring_get_used_event(vq), new, old);
+}
+
+void
+vu_queue_notify(VuDev *dev, VuVirtq *vq)
+{
+    if (unlikely(dev->broken)) {
+        return;
+    }
+
+    if (!vring_notify(dev, vq)) {
+        DPRINT("skipped notify...\n");
+        return;
+    }
+
+    if (eventfd_write(vq->call_fd, 1) < 0) {
+        vu_panic(dev, "Error writing eventfd: %s", strerror(errno));
+    }
+}
+
+static inline void
+vring_used_flags_set_bit(VuVirtq *vq, int mask)
+{
+    uint16_t *flags;
+
+    flags = (uint16_t *)((char*)vq->vring.used +
+                         offsetof(struct vring_used, flags));
+    *flags |= mask;
+}
+
+static inline void
+vring_used_flags_unset_bit(VuVirtq *vq, int mask)
+{
+    uint16_t *flags;
+
+    flags = (uint16_t *)((char*)vq->vring.used +
+                         offsetof(struct vring_used, flags));
+    *flags &= ~mask;
+}
+
+static inline void
+vring_set_avail_event(VuVirtq *vq, uint16_t val)
+{
+    if (!vq->notification) {
+        return;
+    }
+
+    *((uint16_t *) &vq->vring.used->ring[vq->vring.num]) = val;
+}
+
+void
+vu_queue_set_notification(VuDev *dev, VuVirtq *vq, int enable)
+{
+    vq->notification = enable;
+    if (vu_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
+        vring_set_avail_event(vq, vring_avail_idx(vq));
+    } else if (enable) {
+        vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
+    } else {
+        vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
+    }
+    if (enable) {
+        /* Expose avail event/used flags before caller checks the avail idx. */
+        smp_mb();
+    }
+}
+
+static void
+virtqueue_map_desc(VuDev *dev,
+                   unsigned int *p_num_sg, struct iovec *iov,
+                   unsigned int max_num_sg, bool is_write,
+                   uint64_t pa, size_t sz)
+{
+    unsigned num_sg = *p_num_sg;
+
+    assert(num_sg <= max_num_sg);
+
+    if (!sz) {
+        vu_panic(dev, "virtio: zero sized buffers are not allowed");
+        return;
+    }
+
+    iov[num_sg].iov_base = vu_gpa_to_va(dev, pa);
+    iov[num_sg].iov_len = sz;
+    num_sg++;
+
+    *p_num_sg = num_sg;
+}
+
+/* Round number down to multiple */
+#define ALIGN_DOWN(n, m) ((n) / (m) * (m))
+
+/* Round number up to multiple */
+#define ALIGN_UP(n, m) ALIGN_DOWN((n) + (m) - 1, (m))
+
+static void *
+virtqueue_alloc_element(size_t sz,
+                                     unsigned out_num, unsigned in_num)
+{
+    VuVirtqElement *elem;
+    size_t in_sg_ofs = ALIGN_UP(sz, __alignof__(elem->in_sg[0]));
+    size_t out_sg_ofs = in_sg_ofs + in_num * sizeof(elem->in_sg[0]);
+    size_t out_sg_end = out_sg_ofs + out_num * sizeof(elem->out_sg[0]);
+
+    assert(sz >= sizeof(VuVirtqElement));
+    elem = malloc(out_sg_end);
+    elem->out_num = out_num;
+    elem->in_num = in_num;
+    elem->in_sg = (void *)elem + in_sg_ofs;
+    elem->out_sg = (void *)elem + out_sg_ofs;
+    return elem;
+}
+
+void *
+vu_queue_pop(VuDev *dev, VuVirtq *vq, size_t sz)
+{
+    unsigned int i, head, max;
+    VuVirtqElement *elem;
+    unsigned out_num, in_num;
+    struct iovec iov[VIRTQUEUE_MAX_SIZE];
+    struct vring_desc *desc;
+    int rc;
+
+    if (unlikely(dev->broken)) {
+        return NULL;
+    }
+
+    if (vu_queue_empty(dev, vq)) {
+        return NULL;
+    }
+    /* Needed after virtio_queue_empty(), see comment in
+     * virtqueue_num_heads(). */
+    smp_rmb();
+
+    /* When we start there are none of either input nor output. */
+    out_num = in_num = 0;
+
+    max = vq->vring.num;
+    if (vq->inuse >= vq->vring.num) {
+        vu_panic(dev, "Virtqueue size exceeded");
+        return NULL;
+    }
+
+    if (!virtqueue_get_head(dev, vq, vq->last_avail_idx++, &head)) {
+        return NULL;
+    }
+
+    if (vu_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
+        vring_set_avail_event(vq, vq->last_avail_idx);
+    }
+
+    i = head;
+    desc = vq->vring.desc;
+    if (desc[i].flags & VRING_DESC_F_INDIRECT) {
+        if (desc[i].len % sizeof(struct vring_desc)) {
+            vu_panic(dev, "Invalid size for indirect buffer table");
+        }
+
+        /* loop over the indirect descriptor table */
+        max = desc[i].len / sizeof(struct vring_desc);
+        desc = vu_gpa_to_va(dev, desc[i].addr);
+        i = 0;
+    }
+
+    /* Collect all the descriptors */
+    do {
+        if (desc[i].flags & VRING_DESC_F_WRITE) {
+            virtqueue_map_desc(dev, &in_num, iov + out_num,
+                               VIRTQUEUE_MAX_SIZE - out_num, true,
+                               desc[i].addr, desc[i].len);
+        } else {
+            if (in_num) {
+                vu_panic(dev, "Incorrect order for descriptors");
+                return NULL;
+            }
+            virtqueue_map_desc(dev, &out_num, iov,
+                               VIRTQUEUE_MAX_SIZE, false,
+                               desc[i].addr, desc[i].len);
+        }
+
+        /* If we've got too many, that implies a descriptor loop. */
+        if ((in_num + out_num) > max) {
+            vu_panic(dev, "Looped descriptor");
+        }
+        rc = virtqueue_read_next_desc(dev, desc, i, max, &i);
+    } while (rc == VIRTQUEUE_READ_DESC_MORE);
+
+    if (rc == VIRTQUEUE_READ_DESC_ERROR) {
+        return NULL;
+    }
+
+    /* Now copy what we have collected and mapped */
+    elem = virtqueue_alloc_element(sz, out_num, in_num);
+    elem->index = head;
+    for (i = 0; i < out_num; i++) {
+        elem->out_sg[i] = iov[i];
+    }
+    for (i = 0; i < in_num; i++) {
+        elem->in_sg[i] = iov[out_num + i];
+    }
+
+    vq->inuse++;
+
+    return elem;
+}
+
+bool
+vu_queue_rewind(VuDev *dev, VuVirtq *vq, unsigned int num)
+{
+    if (num > vq->inuse) {
+        return false;
+    }
+    vq->last_avail_idx -= num;
+    vq->inuse -= num;
+    return true;
+}
+
+static inline
+void vring_used_write(VuDev *dev, VuVirtq *vq,
+                      struct vring_used_elem *uelem, int i)
+{
+    struct vring_used *used = vq->vring.used;
+
+    used->ring[i] = *uelem;
+    vu_log_write(dev, vq->vring.log_guest_addr +
+                 offsetof(struct vring_used, ring[i]),
+                 sizeof(used->ring[i]));
+}
+
+
+static void
+vu_log_queue_fill(VuDev *dev, VuVirtq *vq,
+                  const VuVirtqElement *elem,
+                  unsigned int len)
+{
+    struct vring_desc *desc = vq->vring.desc;
+    unsigned int i, max, min;
+    unsigned num_bufs = 0;
+
+    max = vq->vring.num;
+    i = elem->index;
+
+    if (desc[i].flags & VRING_DESC_F_INDIRECT) {
+        if (desc[i].len % sizeof(struct vring_desc)) {
+            vu_panic(dev, "Invalid size for indirect buffer table");
+        }
+
+        /* loop over the indirect descriptor table */
+        max = desc[i].len / sizeof(struct vring_desc);
+        desc = vu_gpa_to_va(dev, desc[i].addr);
+        i = 0;
+    }
+
+    do {
+        if (++num_bufs > max) {
+            vu_panic(dev, "Looped descriptor");
+            return;
+        }
+
+        if (desc[i].flags & VRING_DESC_F_WRITE) {
+            min = MIN(desc[i].len, len);
+            vu_log_write(dev, desc[i].addr, min);
+            len -= min;
+        }
+
+    } while (len > 0 &&
+             (virtqueue_read_next_desc(dev, desc, i, max, &i)
+              == VIRTQUEUE_READ_DESC_MORE));
+}
+
+void
+vu_queue_fill(VuDev *dev, VuVirtq *vq,
+              const VuVirtqElement *elem,
+              unsigned int len, unsigned int idx)
+{
+    struct vring_used_elem uelem;
+
+    if (unlikely(dev->broken)) {
+        return;
+    }
+
+    vu_log_queue_fill(dev, vq, elem, len);
+
+    idx = (idx + vq->used_idx) % vq->vring.num;
+
+    uelem.id = elem->index;
+    uelem.len = len;
+    vring_used_write(dev, vq, &uelem, idx);
+}
+
+static inline
+void vring_used_idx_set(VuDev *dev, VuVirtq *vq, uint16_t val)
+{
+    vq->vring.used->idx = val;
+    vu_log_write(dev,
+                 vq->vring.log_guest_addr + offsetof(struct vring_used, idx),
+                 sizeof(vq->vring.used->idx));
+
+    vq->used_idx = val;
+}
+
+void
+vu_queue_flush(VuDev *dev, VuVirtq *vq, unsigned int count)
+{
+    uint16_t old, new;
+
+    if (unlikely(dev->broken)) {
+        return;
+    }
+
+    /* Make sure buffer is written before we update index. */
+    smp_wmb();
+
+    old = vq->used_idx;
+    new = old + count;
+    vring_used_idx_set(dev, vq, new);
+    vq->inuse -= count;
+    if (unlikely((int16_t)(new - vq->signalled_used) < (uint16_t)(new - old))) {
+        vq->signalled_used_valid = false;
+    }
+}
+
+void
+vu_queue_push(VuDev *dev, VuVirtq *vq,
+              const VuVirtqElement *elem, unsigned int len)
+{
+    vu_queue_fill(dev, vq, elem, len, 0);
+    vu_queue_flush(dev, vq, 1);
+}
diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
new file mode 100644
index 0000000..156b50e
--- /dev/null
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -0,0 +1,435 @@
+/*
+ * Vhost User library
+ *
+ * Copyright (c) 2016 Red Hat, Inc.
+ *
+ * Authors:
+ *  Victor Kaplansky <victork@redhat.com>
+ *  Marc-André Lureau <mlureau@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.
+ */
+
+#ifndef LIBVHOST_USER_H
+#define LIBVHOST_USER_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <linux/vhost.h>
+#include "standard-headers/linux/virtio_ring.h"
+
+/* Based on qemu/hw/virtio/vhost-user.c */
+#define VHOST_USER_F_PROTOCOL_FEATURES 30
+#define VHOST_LOG_PAGE 4096
+
+#define VHOST_MAX_NR_VIRTQUEUE 8
+#define VIRTQUEUE_MAX_SIZE 1024
+
+#define VHOST_MEMORY_MAX_NREGIONS 8
+
+enum VhostUserProtocolFeature {
+    VHOST_USER_PROTOCOL_F_MQ = 0,
+    VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
+    VHOST_USER_PROTOCOL_F_RARP = 2,
+
+    VHOST_USER_PROTOCOL_F_MAX
+};
+
+#define VHOST_USER_PROTOCOL_FEATURE_MASK ((1 << VHOST_USER_PROTOCOL_F_MAX) - 1)
+
+typedef enum VhostUserRequest {
+    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_INPUT_GET_CONFIG = 20,
+    VHOST_USER_MAX
+} VhostUserRequest;
+
+typedef struct VhostUserMemoryRegion {
+    uint64_t guest_phys_addr;
+    uint64_t memory_size;
+    uint64_t userspace_addr;
+    uint64_t mmap_offset;
+} VhostUserMemoryRegion;
+
+typedef struct VhostUserMemory {
+    uint32_t nregions;
+    uint32_t padding;
+    VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
+} VhostUserMemory;
+
+typedef struct VhostUserLog {
+    uint64_t mmap_size;
+    uint64_t mmap_offset;
+} VhostUserLog;
+
+#if defined(_WIN32)
+# define VU_PACKED __attribute__((gcc_struct, packed))
+#else
+# define VU_PACKED __attribute__((packed))
+#endif
+
+typedef struct VhostUserMsg {
+    VhostUserRequest request;
+
+#define VHOST_USER_VERSION_MASK     (0x3)
+#define VHOST_USER_REPLY_MASK       (0x1 << 2)
+    uint32_t flags;
+    uint32_t size; /* the following payload size */
+
+    union {
+#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;
+        VhostUserMemory memory;
+        VhostUserLog log;
+    } payload;
+
+    int fds[VHOST_MEMORY_MAX_NREGIONS];
+    int fd_num;
+    uint8_t *data;
+} VU_PACKED VhostUserMsg;
+
+typedef struct VuDevRegion {
+    /* Guest Physical address. */
+    uint64_t gpa;
+    /* Memory region size. */
+    uint64_t size;
+    /* QEMU virtual address (userspace). */
+    uint64_t qva;
+    /* Starting offset in our mmaped space. */
+    uint64_t mmap_offset;
+    /* Start address of mmaped space. */
+    uint64_t mmap_addr;
+} VuDevRegion;
+
+typedef struct VuDev VuDev;
+
+typedef uint64_t (*vu_get_features_cb) (VuDev *dev);
+typedef void (*vu_set_features_cb) (VuDev *dev, uint64_t features);
+typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg,
+                                  int *do_reply);
+typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool started);
+
+typedef struct VuDevIface {
+    /* called by VHOST_USER_GET_FEATURES to get the features bitmask */
+    vu_get_features_cb get_features;
+    /* enable vhost implementation features */
+    vu_set_features_cb set_features;
+    /* get the protocol feature bitmask from the underlying vhost
+     * implementation */
+    vu_get_features_cb get_protocol_features;
+    /* enable protocol features in the underlying vhost implementation. */
+    vu_set_features_cb set_protocol_features;
+    /* process_msg is called for each vhost-user message received */
+    /* skip libvhost-user processing if return value != 0 */
+    vu_process_msg_cb process_msg;
+    /* tells when queues can be processed */
+    vu_queue_set_started_cb queue_set_started;
+} VuDevIface;
+
+typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx);
+
+typedef struct VuRing {
+    unsigned int num;
+    struct vring_desc *desc;
+    struct vring_avail *avail;
+    struct vring_used *used;
+    uint64_t log_guest_addr;
+    uint32_t flags;
+} VuRing;
+
+typedef struct VuVirtq {
+    VuRing vring;
+
+    /* Next head to pop */
+    uint16_t last_avail_idx;
+
+    /* Last avail_idx read from VQ. */
+    uint16_t shadow_avail_idx;
+
+    uint16_t used_idx;
+
+    /* Last used index value we have signalled on */
+    uint16_t signalled_used;
+
+    /* Last used index value we have signalled on */
+    bool signalled_used_valid;
+
+    /* Notification enabled? */
+    bool notification;
+
+    int inuse;
+
+    vu_queue_handler_cb handler;
+
+    int call_fd;
+    int kick_fd;
+    int err_fd;
+    unsigned int enable;
+    bool started;
+} VuVirtq;
+
+enum VuWatchCondtion {
+    VU_WATCH_IN = 1 << 0,
+    VU_WATCH_OUT = 1 << 1,
+    VU_WATCH_PRI = 1 << 2,
+    VU_WATCH_ERR = 1 << 3,
+    VU_WATCH_HUP = 1 << 4,
+};
+
+typedef void (*vu_panic_cb) (VuDev *dev, const char *err);
+typedef void (*vu_watch_cb) (VuDev *dev, int condition, void *data);
+typedef void (*vu_set_watch_cb) (VuDev *dev, int fd, int condition,
+                                 vu_watch_cb cb, void *data);
+typedef void (*vu_remove_watch_cb) (VuDev *dev, int fd);
+
+struct VuDev {
+    int sock;
+    uint32_t nregions;
+    VuDevRegion regions[VHOST_MEMORY_MAX_NREGIONS];
+    VuVirtq vq[VHOST_MAX_NR_VIRTQUEUE];
+    int log_call_fd;
+    uint64_t log_size;
+    uint8_t *log_table;
+    uint64_t features;
+    uint64_t protocol_features;
+    bool broken;
+
+    /* @set_watch: add or update the given fd to the watch set,
+     * call cb when condition is met */
+    vu_set_watch_cb set_watch;
+
+    /* @remove_watch: remove the given fd from the watch set */
+    vu_remove_watch_cb remove_watch;
+
+    /* @panic: encountered an unrecoverable error, you may try to
+     * re-initialize */
+    vu_panic_cb panic;
+    const VuDevIface *iface;
+};
+
+typedef struct VuVirtqElement {
+    unsigned int index;
+    unsigned int out_num;
+    unsigned int in_num;
+    struct iovec *in_sg;
+    struct iovec *out_sg;
+} VuVirtqElement;
+
+/**
+ * vu_init:
+ * @dev: a VuDev context
+ * @socket: the socket connected to vhost-user master
+ * @panic: a panic callback
+ * @set_watch: a set_watch callback
+ * @remove_watch: a remove_watch callback
+ * @iface: a VuDevIface structure with vhost-user device callbacks
+ *
+ * Intializes a VuDev vhost-user context.
+ **/
+void vu_init(VuDev *dev,
+             int socket,
+             vu_panic_cb panic,
+             vu_set_watch_cb set_watch,
+             vu_remove_watch_cb remove_watch,
+             const VuDevIface *iface);
+
+
+/**
+ * vu_deinit:
+ * @dev: a VuDev context
+ *
+ * Cleans up the VuDev context
+ */
+void vu_deinit(VuDev *dev);
+
+/**
+ * vu_dispatch:
+ * @dev: a VuDev context
+ *
+ * Process one vhost-user message.
+ *
+ * Returns: TRUE on success, FALSE on failure.
+ */
+bool vu_dispatch(VuDev *dev);
+
+/**
+ * vu_gpa_to_va:
+ * @dev: a VuDev context
+ * @guest_addr: guest address
+ *
+ * Translate a guest address to a pointer. Returns NULL on failure.
+ */
+void *vu_gpa_to_va(VuDev *dev, uint64_t guest_addr);
+
+/**
+ * vu_get_queue:
+ * @dev: a VuDev context
+ * @qidx: queue index
+ *
+ * Returns the queue number @qidx.
+ */
+VuVirtq *vu_get_queue(VuDev *dev, int qidx);
+
+/**
+ * vu_set_queue_handler:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @handler: the queue handler callback
+ *
+ * Set the queue handler. This function may be called several times
+ * for the same queue. If called with NULL @handler, the handler is
+ * removed.
+ */
+void vu_set_queue_handler(VuDev *dev, VuVirtq *vq,
+                          vu_queue_handler_cb handler);
+
+
+/**
+ * vu_queue_set_notification:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @enable: state
+ *
+ * Set whether the queue notifies (via event index or interrupt)
+ */
+void vu_queue_set_notification(VuDev *dev, VuVirtq *vq, int enable);
+
+/**
+ * vu_queue_enabled:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ *
+ * Returns: whether the queue is enabled.
+ */
+bool vu_queue_enabled(VuDev *dev, VuVirtq *vq);
+
+/**
+ * vu_queue_enabled:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ *
+ * Returns: whether the queue is empty.
+ */
+int vu_queue_empty(VuDev *dev, VuVirtq *vq);
+
+/**
+ * vu_queue_notify:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ *
+ * Request to notify the queue via callfd (skipped if unnecessary)
+ */
+void vu_queue_notify(VuDev *dev, VuVirtq *vq);
+
+/**
+ * vu_queue_pop:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @sz: the size of struct to return (must be >= VuVirtqElement)
+ *
+ * Returns: a VuVirtqElement filled from the queue or NULL.
+ */
+void *vu_queue_pop(VuDev *dev, VuVirtq *vq, size_t sz);
+
+/**
+ * vu_queue_rewind:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @num: number of elements to push back
+ *
+ * Pretend that elements weren't popped from the virtqueue.  The next
+ * virtqueue_pop() will refetch the oldest element.
+ *
+ * Returns: true on success, false if @num is greater than the number of in use
+ * elements.
+ */
+bool vu_queue_rewind(VuDev *dev, VuVirtq *vq, unsigned int num);
+
+/**
+ * vu_queue_fill:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @elem: a VuVirtqElement
+ * @len: length in bytes to write
+ * @idx: optional offset for the used ring index (0 in general)
+ *
+ * Fill the used ring with @elem element.
+ */
+void vu_queue_fill(VuDev *dev, VuVirtq *vq,
+                   const VuVirtqElement *elem,
+                   unsigned int len, unsigned int idx);
+
+/**
+ * vu_queue_push:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @elem: a VuVirtqElement
+ * @len: length in bytes to write
+ *
+ * Helper that combines vu_queue_fill() with a vu_queue_flush().
+ */
+void vu_queue_push(VuDev *dev, VuVirtq *vq,
+                   const VuVirtqElement *elem, unsigned int len);
+
+/**
+ * vu_queue_flush:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @num: number of elements to flush
+ *
+ * Mark the last number of elements as done (used.idx is updated by
+ * num elements).
+*/
+void vu_queue_flush(VuDev *dev, VuVirtq *vq, unsigned int num);
+
+/**
+ * vu_queue_get_avail_bytes:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @in_bytes: in bytes
+ * @out_bytes: out bytes
+ * @max_in_bytes: stop counting after max_in_bytes
+ * @max_out_bytes: stop counting after max_out_bytes
+ *
+ * Count the number of available bytes, up to max_in_bytes/max_out_bytes.
+ */
+void vu_queue_get_avail_bytes(VuDev *vdev, VuVirtq *vq, unsigned int *in_bytes,
+                              unsigned int *out_bytes,
+                              unsigned max_in_bytes, unsigned max_out_bytes);
+
+/**
+ * vu_queue_avail_bytes:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ * @in_bytes: expected in bytes
+ * @out_bytes: expected out bytes
+ *
+ * Returns: true if in_bytes <= in_total && out_bytes <= out_total
+ */
+bool vu_queue_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int in_bytes,
+                          unsigned int out_bytes);
+
+#endif /* LIBVHOST_USER_H */
diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index 47b79d9..e0732cc 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -562,7 +562,7 @@ static void amdvi_mmio_trace(hwaddr addr, unsigned size)
         trace_amdvi_mmio_read(amdvi_mmio_high[index], addr, size, addr & ~0x07);
     } else {
         index = index >= AMDVI_MMIO_REGS_LOW ? AMDVI_MMIO_REGS_LOW : index;
-        trace_amdvi_mmio_read(amdvi_mmio_high[index], addr, size, addr & ~0x07);
+        trace_amdvi_mmio_read(amdvi_mmio_low[index], addr, size, addr & ~0x07);
     }
 }
 
diff --git a/hw/i386/amd_iommu.h b/hw/i386/amd_iommu.h
index 884926e..0d3dc6a 100644
--- a/hw/i386/amd_iommu.h
+++ b/hw/i386/amd_iommu.h
@@ -49,8 +49,8 @@
 #define AMDVI_CAPAB_INIT_TYPE         (3 << 16)
 
 /* No. of used MMIO registers */
-#define AMDVI_MMIO_REGS_HIGH  8
-#define AMDVI_MMIO_REGS_LOW   7
+#define AMDVI_MMIO_REGS_HIGH  7
+#define AMDVI_MMIO_REGS_LOW   8
 
 /* MMIO registers */
 #define AMDVI_MMIO_DEVICE_TABLE       0x0000
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 24fae16..637d545 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -982,8 +982,8 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
                pci_get_function_0(pci_dev)) {
         error_setg(errp, "PCI: slot %d function 0 already ocuppied by %s,"
                    " new func %s cannot be exposed to guest.",
-                   PCI_SLOT(devfn),
-                   bus->devices[PCI_DEVFN(PCI_SLOT(devfn), 0)]->name,
+                   PCI_SLOT(pci_get_function_0(pci_dev)->devfn),
+                   pci_get_function_0(pci_dev)->name,
                    name);
 
        return NULL;
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index f5c1d98..0765068 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -1098,7 +1098,7 @@ static int virtio_ccw_set_guest_notifier(VirtioCcwDevice *dev, int n,
          * We do not support individual masking for channel devices, so we
          * need to manually trigger any guest masking callbacks here.
          */
-        if (k->guest_notifier_mask) {
+        if (k->guest_notifier_mask && vdev->use_guest_notifier_mask) {
             k->guest_notifier_mask(vdev, n, false);
         }
         /* get lost events and re-inject */
@@ -1107,7 +1107,7 @@ static int virtio_ccw_set_guest_notifier(VirtioCcwDevice *dev, int n,
             event_notifier_set(notifier);
         }
     } else {
-        if (k->guest_notifier_mask) {
+        if (k->guest_notifier_mask && vdev->use_guest_notifier_mask) {
             k->guest_notifier_mask(vdev, n, true);
         }
         if (with_irqfd) {
diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
index 17412cb7..60654dc 100644
--- a/hw/virtio/virtio-mmio.c
+++ b/hw/virtio/virtio-mmio.c
@@ -402,7 +402,7 @@ static int virtio_mmio_set_guest_notifier(DeviceState *d, int n, bool assign,
         event_notifier_cleanup(notifier);
     }
 
-    if (vdc->guest_notifier_mask) {
+    if (vdc->guest_notifier_mask && vdev->use_guest_notifier_mask) {
         vdc->guest_notifier_mask(vdev, n, !assign);
     }
 
diff --git a/tests/Makefile.include b/tests/Makefile.include
index 4841d58..f776404 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -689,7 +689,7 @@ tests/test-filter-mirror$(EXESUF): tests/test-filter-mirror.o $(qtest-obj-y)
 tests/test-filter-redirector$(EXESUF): tests/test-filter-redirector.o $(qtest-obj-y)
 tests/test-x86-cpuid-compat$(EXESUF): tests/test-x86-cpuid-compat.o $(qtest-obj-y)
 tests/ivshmem-test$(EXESUF): tests/ivshmem-test.o contrib/ivshmem-server/ivshmem-server.o $(libqos-pc-obj-y)
-tests/vhost-user-bridge$(EXESUF): tests/vhost-user-bridge.o
+tests/vhost-user-bridge$(EXESUF): tests/vhost-user-bridge.o contrib/libvhost-user/libvhost-user.o $(test-util-obj-y)
 tests/test-uuid$(EXESUF): tests/test-uuid.o $(test-util-obj-y)
 tests/test-arm-mptimer$(EXESUF): tests/test-arm-mptimer.o
 
diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
index 775e031..8618c20 100644
--- a/tests/vhost-user-bridge.c
+++ b/tests/vhost-user-bridge.c
@@ -30,17 +30,9 @@
 #define _FILE_OFFSET_BITS 64
 
 #include "qemu/osdep.h"
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <sys/unistd.h>
-#include <sys/eventfd.h>
-#include <arpa/inet.h>
-#include <netdb.h>
-#include <linux/vhost.h>
-
-#include "qemu/atomic.h"
+#include "qemu/iov.h"
 #include "standard-headers/linux/virtio_net.h"
-#include "standard-headers/linux/virtio_ring.h"
+#include "contrib/libvhost-user/libvhost-user.h"
 
 #define VHOST_USER_BRIDGE_DEBUG 1
 
@@ -64,6 +56,17 @@ typedef struct Dispatcher {
     Event events[FD_SETSIZE];
 } Dispatcher;
 
+typedef struct VubrDev {
+    VuDev vudev;
+    Dispatcher dispatcher;
+    int backend_udp_sock;
+    struct sockaddr_in backend_udp_dest;
+    int hdrlen;
+    int sock;
+    int ready;
+    int quit;
+} VubrDev;
+
 static void
 vubr_die(const char *s)
 {
@@ -101,8 +104,6 @@ dispatcher_add(Dispatcher *dispr, int sock, void *ctx, CallbackFunc cb)
     return 0;
 }
 
-/* dispatcher_remove() is not currently in use but may be useful
- * in the future. */
 static int
 dispatcher_remove(Dispatcher *dispr, int sock)
 {
@@ -157,1039 +158,313 @@ dispatcher_wait(Dispatcher *dispr, uint32_t timeout)
     return 0;
 }
 
-typedef struct VubrVirtq {
-    int call_fd;
-    int kick_fd;
-    uint32_t size;
-    uint16_t last_avail_index;
-    uint16_t last_used_index;
-    struct vring_desc *desc;
-    struct vring_avail *avail;
-    struct vring_used *used;
-    uint64_t log_guest_addr;
-    int enable;
-} VubrVirtq;
-
-/* Based on qemu/hw/virtio/vhost-user.c */
-
-#define VHOST_MEMORY_MAX_NREGIONS    8
-#define VHOST_USER_F_PROTOCOL_FEATURES 30
-/* v1.0 compliant. */
-#define VIRTIO_F_VERSION_1		32
-
-#define VHOST_LOG_PAGE 4096
-
-enum VhostUserProtocolFeature {
-    VHOST_USER_PROTOCOL_F_MQ = 0,
-    VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
-    VHOST_USER_PROTOCOL_F_RARP = 2,
-
-    VHOST_USER_PROTOCOL_F_MAX
-};
-
-#define VHOST_USER_PROTOCOL_FEATURE_MASK ((1 << VHOST_USER_PROTOCOL_F_MAX) - 1)
-
-typedef enum VhostUserRequest {
-    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_MAX
-} VhostUserRequest;
-
-typedef struct VhostUserMemoryRegion {
-    uint64_t guest_phys_addr;
-    uint64_t memory_size;
-    uint64_t userspace_addr;
-    uint64_t mmap_offset;
-} VhostUserMemoryRegion;
-
-typedef struct VhostUserMemory {
-    uint32_t nregions;
-    uint32_t padding;
-    VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
-} VhostUserMemory;
-
-typedef struct VhostUserLog {
-    uint64_t mmap_size;
-    uint64_t mmap_offset;
-} VhostUserLog;
-
-typedef struct VhostUserMsg {
-    VhostUserRequest request;
-
-#define VHOST_USER_VERSION_MASK     (0x3)
-#define VHOST_USER_REPLY_MASK       (0x1<<2)
-    uint32_t flags;
-    uint32_t size; /* the following payload size */
-    union {
-#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;
-        VhostUserMemory memory;
-        VhostUserLog log;
-    } payload;
-    int fds[VHOST_MEMORY_MAX_NREGIONS];
-    int fd_num;
-} QEMU_PACKED VhostUserMsg;
-
-#define VHOST_USER_HDR_SIZE offsetof(VhostUserMsg, payload.u64)
-
-/* The version of the protocol we support */
-#define VHOST_USER_VERSION    (0x1)
-
-#define MAX_NR_VIRTQUEUE (8)
-
-typedef struct VubrDevRegion {
-    /* Guest Physical address. */
-    uint64_t gpa;
-    /* Memory region size. */
-    uint64_t size;
-    /* QEMU virtual address (userspace). */
-    uint64_t qva;
-    /* Starting offset in our mmaped space. */
-    uint64_t mmap_offset;
-    /* Start address of mmaped space. */
-    uint64_t mmap_addr;
-} VubrDevRegion;
-
-typedef struct VubrDev {
-    int sock;
-    Dispatcher dispatcher;
-    uint32_t nregions;
-    VubrDevRegion regions[VHOST_MEMORY_MAX_NREGIONS];
-    VubrVirtq vq[MAX_NR_VIRTQUEUE];
-    int log_call_fd;
-    uint64_t log_size;
-    uint8_t *log_table;
-    int backend_udp_sock;
-    struct sockaddr_in backend_udp_dest;
-    int ready;
-    uint64_t features;
-    int hdrlen;
-} VubrDev;
-
-static const char *vubr_request_str[] = {
-    [VHOST_USER_NONE]                   =  "VHOST_USER_NONE",
-    [VHOST_USER_GET_FEATURES]           =  "VHOST_USER_GET_FEATURES",
-    [VHOST_USER_SET_FEATURES]           =  "VHOST_USER_SET_FEATURES",
-    [VHOST_USER_SET_OWNER]              =  "VHOST_USER_SET_OWNER",
-    [VHOST_USER_RESET_OWNER]           =  "VHOST_USER_RESET_OWNER",
-    [VHOST_USER_SET_MEM_TABLE]          =  "VHOST_USER_SET_MEM_TABLE",
-    [VHOST_USER_SET_LOG_BASE]           =  "VHOST_USER_SET_LOG_BASE",
-    [VHOST_USER_SET_LOG_FD]             =  "VHOST_USER_SET_LOG_FD",
-    [VHOST_USER_SET_VRING_NUM]          =  "VHOST_USER_SET_VRING_NUM",
-    [VHOST_USER_SET_VRING_ADDR]         =  "VHOST_USER_SET_VRING_ADDR",
-    [VHOST_USER_SET_VRING_BASE]         =  "VHOST_USER_SET_VRING_BASE",
-    [VHOST_USER_GET_VRING_BASE]         =  "VHOST_USER_GET_VRING_BASE",
-    [VHOST_USER_SET_VRING_KICK]         =  "VHOST_USER_SET_VRING_KICK",
-    [VHOST_USER_SET_VRING_CALL]         =  "VHOST_USER_SET_VRING_CALL",
-    [VHOST_USER_SET_VRING_ERR]          =  "VHOST_USER_SET_VRING_ERR",
-    [VHOST_USER_GET_PROTOCOL_FEATURES]  =  "VHOST_USER_GET_PROTOCOL_FEATURES",
-    [VHOST_USER_SET_PROTOCOL_FEATURES]  =  "VHOST_USER_SET_PROTOCOL_FEATURES",
-    [VHOST_USER_GET_QUEUE_NUM]          =  "VHOST_USER_GET_QUEUE_NUM",
-    [VHOST_USER_SET_VRING_ENABLE]       =  "VHOST_USER_SET_VRING_ENABLE",
-    [VHOST_USER_SEND_RARP]              =  "VHOST_USER_SEND_RARP",
-    [VHOST_USER_MAX]                    =  "VHOST_USER_MAX",
-};
-
 static void
-print_buffer(uint8_t *buf, size_t len)
+vubr_handle_tx(VuDev *dev, int qidx)
 {
-    int i;
-    printf("Raw buffer:\n");
-    for (i = 0; i < len; i++) {
-        if (i % 16 == 0) {
-            printf("\n");
-        }
-        if (i % 4 == 0) {
-            printf("   ");
-        }
-        printf("%02x ", buf[i]);
-    }
-    printf("\n............................................................\n");
-}
+    VuVirtq *vq = vu_get_queue(dev, qidx);
+    VubrDev *vubr = container_of(dev, VubrDev, vudev);
+    int hdrlen = vubr->hdrlen;
+    VuVirtqElement *elem = NULL;
 
-/* Translate guest physical address to our virtual address.  */
-static uint64_t
-gpa_to_va(VubrDev *dev, uint64_t guest_addr)
-{
-    int i;
-
-    /* Find matching memory region.  */
-    for (i = 0; i < dev->nregions; i++) {
-        VubrDevRegion *r = &dev->regions[i];
-
-        if ((guest_addr >= r->gpa) && (guest_addr < (r->gpa + r->size))) {
-            return guest_addr - r->gpa + r->mmap_addr + r->mmap_offset;
-        }
-    }
-
-    assert(!"address not found in regions");
-    return 0;
-}
-
-/* Translate qemu virtual address to our virtual address.  */
-static uint64_t
-qva_to_va(VubrDev *dev, uint64_t qemu_addr)
-{
-    int i;
+    assert(qidx % 2);
 
-    /* Find matching memory region.  */
-    for (i = 0; i < dev->nregions; i++) {
-        VubrDevRegion *r = &dev->regions[i];
+    for (;;) {
+        ssize_t ret;
+        unsigned int out_num;
+        struct iovec sg[VIRTQUEUE_MAX_SIZE], *out_sg;
 
-        if ((qemu_addr >= r->qva) && (qemu_addr < (r->qva + r->size))) {
-            return qemu_addr - r->qva + r->mmap_addr + r->mmap_offset;
+        elem = vu_queue_pop(dev, vq, sizeof(VuVirtqElement));
+        if (!elem) {
+            break;
         }
-    }
-
-    assert(!"address not found in regions");
-    return 0;
-}
 
-static void
-vubr_message_read(int conn_fd, VhostUserMsg *vmsg)
-{
-    char control[CMSG_SPACE(VHOST_MEMORY_MAX_NREGIONS * sizeof(int))] = { };
-    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),
-    };
-    size_t fd_size;
-    struct cmsghdr *cmsg;
-    int rc;
-
-    rc = recvmsg(conn_fd, &msg, 0);
-
-    if (rc == 0) {
-        vubr_die("recvmsg");
-        fprintf(stderr, "Peer disconnected.\n");
-        exit(1);
-    }
-    if (rc < 0) {
-        vubr_die("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) {
-            fd_size = cmsg->cmsg_len - CMSG_LEN(0);
-            vmsg->fd_num = fd_size / sizeof(int);
-            memcpy(vmsg->fds, CMSG_DATA(cmsg), fd_size);
+        out_num = elem->out_num;
+        out_sg = elem->out_sg;
+        if (out_num < 1) {
+            fprintf(stderr, "virtio-net header not in first element\n");
             break;
         }
-    }
-
-    if (vmsg->size > sizeof(vmsg->payload)) {
-        fprintf(stderr,
-                "Error: too big message request: %d, size: vmsg->size: %u, "
-                "while sizeof(vmsg->payload) = %zu\n",
-                vmsg->request, vmsg->size, sizeof(vmsg->payload));
-        exit(1);
-    }
-
-    if (vmsg->size) {
-        rc = read(conn_fd, &vmsg->payload, vmsg->size);
-        if (rc == 0) {
-            vubr_die("recvmsg");
-            fprintf(stderr, "Peer disconnected.\n");
-            exit(1);
+        if (VHOST_USER_BRIDGE_DEBUG) {
+            iov_hexdump(out_sg, out_num, stderr, "TX:", 1024);
         }
-        if (rc < 0) {
-            vubr_die("recvmsg");
+
+        if (hdrlen) {
+            unsigned sg_num = iov_copy(sg, ARRAY_SIZE(sg),
+                                       out_sg, out_num,
+                                       hdrlen, -1);
+            out_num = sg_num;
+            out_sg = sg;
         }
 
-        assert(rc == vmsg->size);
-    }
-}
+        struct msghdr msg = {
+            .msg_name = (struct sockaddr *) &vubr->backend_udp_dest,
+            .msg_namelen = sizeof(struct sockaddr_in),
+            .msg_iov = out_sg,
+            .msg_iovlen = out_num,
+        };
+        do {
+            ret = sendmsg(vubr->backend_udp_sock, &msg, 0);
+        } while (ret == -1 && (errno == EAGAIN || errno == EINTR));
 
-static void
-vubr_message_write(int conn_fd, VhostUserMsg *vmsg)
-{
-    int rc;
+        if (ret == -1) {
+            vubr_die("sendmsg()");
+        }
 
-    do {
-        rc = write(conn_fd, vmsg, VHOST_USER_HDR_SIZE + vmsg->size);
-    } while (rc < 0 && errno == EINTR);
+        vu_queue_push(dev, vq, elem, 0);
+        vu_queue_notify(dev, vq);
 
-    if (rc < 0) {
-        vubr_die("write");
+        free(elem);
+        elem = NULL;
     }
-}
 
-static void
-vubr_backend_udp_sendbuf(VubrDev *dev, uint8_t *buf, size_t len)
-{
-    int slen = sizeof(struct sockaddr_in);
-
-    if (sendto(dev->backend_udp_sock, buf, len, 0,
-               (struct sockaddr *) &dev->backend_udp_dest, slen) == -1) {
-        vubr_die("sendto()");
-    }
+    free(elem);
 }
 
-static int
-vubr_backend_udp_recvbuf(VubrDev *dev, uint8_t *buf, size_t buflen)
+static void
+iov_restore_front(struct iovec *front, struct iovec *iov, size_t bytes)
 {
-    int slen = sizeof(struct sockaddr_in);
-    int rc;
+    struct iovec *cur;
 
-    rc = recvfrom(dev->backend_udp_sock, buf, buflen, 0,
-                  (struct sockaddr *) &dev->backend_udp_dest,
-                  (socklen_t *)&slen);
-    if (rc == -1) {
-        vubr_die("recvfrom()");
+    for (cur = front; front != iov; cur++) {
+        bytes -= cur->iov_len;
     }
 
-    return rc;
+    cur->iov_base -= bytes;
+    cur->iov_len += bytes;
 }
 
 static void
-vubr_consume_raw_packet(VubrDev *dev, uint8_t *buf, uint32_t len)
+iov_truncate(struct iovec *iov, unsigned iovc, size_t bytes)
 {
-    int hdrlen = dev->hdrlen;
-    DPRINT("    hdrlen = %d\n", dev->hdrlen);
+    unsigned i;
 
-    if (VHOST_USER_BRIDGE_DEBUG) {
-        print_buffer(buf, len);
-    }
-    vubr_backend_udp_sendbuf(dev, buf + hdrlen, len - hdrlen);
-}
+    for (i = 0; i < iovc; i++, iov++) {
+        if (bytes < iov->iov_len) {
+            iov->iov_len = bytes;
+            return;
+        }
 
-/* Kick the log_call_fd if required. */
-static void
-vubr_log_kick(VubrDev *dev)
-{
-    if (dev->log_call_fd != -1) {
-        DPRINT("Kicking the QEMU's log...\n");
-        eventfd_write(dev->log_call_fd, 1);
+        bytes -= iov->iov_len;
     }
-}
 
-/* Kick the guest if necessary. */
-static void
-vubr_virtqueue_kick(VubrVirtq *vq)
-{
-    if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)) {
-        DPRINT("Kicking the guest...\n");
-        eventfd_write(vq->call_fd, 1);
-    }
+    assert(!"couldn't truncate iov");
 }
 
 static void
-vubr_log_page(uint8_t *log_table, uint64_t page)
+vubr_backend_recv_cb(int sock, void *ctx)
 {
-    DPRINT("Logged dirty guest page: %"PRId64"\n", page);
-    atomic_or(&log_table[page / 8], 1 << (page % 8));
-}
+    VubrDev *vubr = (VubrDev *) ctx;
+    VuDev *dev = &vubr->vudev;
+    VuVirtq *vq = vu_get_queue(dev, 0);
+    VuVirtqElement *elem = NULL;
+    struct iovec mhdr_sg[VIRTQUEUE_MAX_SIZE];
+    struct virtio_net_hdr_mrg_rxbuf mhdr;
+    unsigned mhdr_cnt = 0;
+    int hdrlen = vubr->hdrlen;
+    int i = 0;
+    struct virtio_net_hdr hdr = {
+        .flags = 0,
+        .gso_type = VIRTIO_NET_HDR_GSO_NONE
+    };
 
-static void
-vubr_log_write(VubrDev *dev, uint64_t address, uint64_t length)
-{
-    uint64_t page;
+    DPRINT("\n\n   ***   IN UDP RECEIVE CALLBACK    ***\n\n");
+    DPRINT("    hdrlen = %d\n", hdrlen);
 
-    if (!(dev->features & (1ULL << VHOST_F_LOG_ALL)) ||
-        !dev->log_table || !length) {
+    if (!vu_queue_enabled(dev, vq) ||
+        !vu_queue_avail_bytes(dev, vq, hdrlen, 0)) {
+        DPRINT("Got UDP packet, but no available descriptors on RX virtq.\n");
         return;
     }
 
-    assert(dev->log_size > ((address + length - 1) / VHOST_LOG_PAGE / 8));
-
-    page = address / VHOST_LOG_PAGE;
-    while (page * VHOST_LOG_PAGE < address + length) {
-        vubr_log_page(dev->log_table, page);
-        page += VHOST_LOG_PAGE;
-    }
-    vubr_log_kick(dev);
-}
-
-static void
-vubr_post_buffer(VubrDev *dev, VubrVirtq *vq, uint8_t *buf, int32_t len)
-{
-    struct vring_desc *desc = vq->desc;
-    struct vring_avail *avail = vq->avail;
-    struct vring_used *used = vq->used;
-    uint64_t log_guest_addr = vq->log_guest_addr;
-    int32_t remaining_len = len;
-
-    unsigned int size = vq->size;
-
-    uint16_t avail_index = atomic_mb_read(&avail->idx);
-
-    /* We check the available descriptors before posting the
-     * buffer, so here we assume that enough available
-     * descriptors. */
-    assert(vq->last_avail_index != avail_index);
-    uint16_t a_index = vq->last_avail_index % size;
-    uint16_t u_index = vq->last_used_index % size;
-    uint16_t d_index = avail->ring[a_index];
-
-    int i = d_index;
-    uint32_t written_len = 0;
-
     do {
-        DPRINT("Post packet to guest on vq:\n");
-        DPRINT("    size             = %d\n", vq->size);
-        DPRINT("    last_avail_index = %d\n", vq->last_avail_index);
-        DPRINT("    last_used_index  = %d\n", vq->last_used_index);
-        DPRINT("    a_index = %d\n", a_index);
-        DPRINT("    u_index = %d\n", u_index);
-        DPRINT("    d_index = %d\n", d_index);
-        DPRINT("    desc[%d].addr    = 0x%016"PRIx64"\n", i, desc[i].addr);
-        DPRINT("    desc[%d].len     = %d\n", i, desc[i].len);
-        DPRINT("    desc[%d].flags   = %d\n", i, desc[i].flags);
-        DPRINT("    avail->idx = %d\n", avail_index);
-        DPRINT("    used->idx  = %d\n", used->idx);
-
-        if (!(desc[i].flags & VRING_DESC_F_WRITE)) {
-            /* FIXME: we should find writable descriptor. */
-            fprintf(stderr, "Error: descriptor is not writable. Exiting.\n");
-            exit(1);
-        }
-
-        void *chunk_start = (void *)(uintptr_t)gpa_to_va(dev, desc[i].addr);
-        uint32_t chunk_len = desc[i].len;
-        uint32_t chunk_write_len = MIN(remaining_len, chunk_len);
+        struct iovec *sg;
+        ssize_t ret, total = 0;
+        unsigned int num;
 
-        memcpy(chunk_start, buf + written_len, chunk_write_len);
-        vubr_log_write(dev, desc[i].addr, chunk_write_len);
-        remaining_len -= chunk_write_len;
-        written_len += chunk_write_len;
-
-        if ((remaining_len == 0) || !(desc[i].flags & VRING_DESC_F_NEXT)) {
+        elem = vu_queue_pop(dev, vq, sizeof(VuVirtqElement));
+        if (!elem) {
             break;
         }
 
-        i = desc[i].next;
-    } while (1);
-
-    if (remaining_len > 0) {
-            fprintf(stderr,
-                    "Too long packet for RX, remaining_len = %d, Dropping...\n",
-                    remaining_len);
-            return;
-    }
-
-    /* Add descriptor to the used ring. */
-    used->ring[u_index].id = d_index;
-    used->ring[u_index].len = len;
-    vubr_log_write(dev,
-                   log_guest_addr + offsetof(struct vring_used, ring[u_index]),
-                   sizeof(used->ring[u_index]));
-
-    vq->last_avail_index++;
-    vq->last_used_index++;
-
-    atomic_mb_set(&used->idx, vq->last_used_index);
-    vubr_log_write(dev,
-                   log_guest_addr + offsetof(struct vring_used, idx),
-                   sizeof(used->idx));
-
-    /* Kick the guest if necessary. */
-    vubr_virtqueue_kick(vq);
-}
-
-static int
-vubr_process_desc(VubrDev *dev, VubrVirtq *vq)
-{
-    struct vring_desc *desc = vq->desc;
-    struct vring_avail *avail = vq->avail;
-    struct vring_used *used = vq->used;
-    uint64_t log_guest_addr = vq->log_guest_addr;
-
-    unsigned int size = vq->size;
-
-    uint16_t a_index = vq->last_avail_index % size;
-    uint16_t u_index = vq->last_used_index % size;
-    uint16_t d_index = avail->ring[a_index];
-
-    uint32_t i, len = 0;
-    size_t buf_size = 4096;
-    uint8_t buf[4096];
-
-    DPRINT("Chunks: ");
-    i = d_index;
-    do {
-        void *chunk_start = (void *)(uintptr_t)gpa_to_va(dev, desc[i].addr);
-        uint32_t chunk_len = desc[i].len;
-
-        assert(!(desc[i].flags & VRING_DESC_F_WRITE));
-
-        if (len + chunk_len < buf_size) {
-            memcpy(buf + len, chunk_start, chunk_len);
-            DPRINT("%d ", chunk_len);
-        } else {
-            fprintf(stderr, "Error: too long packet. Dropping...\n");
+        if (elem->in_num < 1) {
+            fprintf(stderr, "virtio-net contains no in buffers\n");
             break;
         }
 
-        len += chunk_len;
-
-        if (!(desc[i].flags & VRING_DESC_F_NEXT)) {
-            break;
+        sg = elem->in_sg;
+        num = elem->in_num;
+        if (i == 0) {
+            if (hdrlen == 12) {
+                mhdr_cnt = iov_copy(mhdr_sg, ARRAY_SIZE(mhdr_sg),
+                                    sg, elem->in_num,
+                                    offsetof(typeof(mhdr), num_buffers),
+                                    sizeof(mhdr.num_buffers));
+            }
+            iov_from_buf(sg, elem->in_num, 0, &hdr, sizeof hdr);
+            total += hdrlen;
+            assert(iov_discard_front(&sg, &num, hdrlen) == hdrlen);
         }
 
-        i = desc[i].next;
-    } while (1);
-    DPRINT("\n");
-
-    if (!len) {
-        return -1;
-    }
-
-    /* Add descriptor to the used ring. */
-    used->ring[u_index].id = d_index;
-    used->ring[u_index].len = len;
-    vubr_log_write(dev,
-                   log_guest_addr + offsetof(struct vring_used, ring[u_index]),
-                   sizeof(used->ring[u_index]));
-
-    vubr_consume_raw_packet(dev, buf, len);
-
-    return 0;
-}
+        struct msghdr msg = {
+            .msg_name = (struct sockaddr *) &vubr->backend_udp_dest,
+            .msg_namelen = sizeof(struct sockaddr_in),
+            .msg_iov = sg,
+            .msg_iovlen = elem->in_num,
+            .msg_flags = MSG_DONTWAIT,
+        };
+        do {
+            ret = recvmsg(vubr->backend_udp_sock, &msg, 0);
+        } while (ret == -1 && (errno == EINTR));
 
-static void
-vubr_process_avail(VubrDev *dev, VubrVirtq *vq)
-{
-    struct vring_avail *avail = vq->avail;
-    struct vring_used *used = vq->used;
-    uint64_t log_guest_addr = vq->log_guest_addr;
-
-    while (vq->last_avail_index != atomic_mb_read(&avail->idx)) {
-        vubr_process_desc(dev, vq);
-        vq->last_avail_index++;
-        vq->last_used_index++;
-    }
+        if (i == 0) {
+            iov_restore_front(elem->in_sg, sg, hdrlen);
+        }
 
-    atomic_mb_set(&used->idx, vq->last_used_index);
-    vubr_log_write(dev,
-                   log_guest_addr + offsetof(struct vring_used, idx),
-                   sizeof(used->idx));
-}
+        if (ret == -1) {
+            if (errno == EWOULDBLOCK) {
+                vu_queue_rewind(dev, vq, 1);
+                break;
+            }
 
-static void
-vubr_backend_recv_cb(int sock, void *ctx)
-{
-    VubrDev *dev = (VubrDev *) ctx;
-    VubrVirtq *rx_vq = &dev->vq[0];
-    uint8_t buf[4096];
-    struct virtio_net_hdr_v1 *hdr = (struct virtio_net_hdr_v1 *)buf;
-    int hdrlen = dev->hdrlen;
-    int buflen = sizeof(buf);
-    int len;
-
-    if (!dev->ready) {
-        return;
-    }
+            vubr_die("recvmsg()");
+        }
 
-    DPRINT("\n\n   ***   IN UDP RECEIVE CALLBACK    ***\n\n");
-    DPRINT("    hdrlen = %d\n", hdrlen);
+        total += ret;
+        iov_truncate(elem->in_sg, elem->in_num, total);
+        vu_queue_fill(dev, vq, elem, total, i++);
 
-    uint16_t avail_index = atomic_mb_read(&rx_vq->avail->idx);
+        free(elem);
+        elem = NULL;
+    } while (false); /* could loop if DONTWAIT worked? */
 
-    /* If there is no available descriptors, just do nothing.
-     * The buffer will be handled by next arrived UDP packet,
-     * or next kick on receive virtq. */
-    if (rx_vq->last_avail_index == avail_index) {
-        DPRINT("Got UDP packet, but no available descriptors on RX virtq.\n");
-        return;
+    if (mhdr_cnt) {
+        mhdr.num_buffers = i;
+        iov_from_buf(mhdr_sg, mhdr_cnt,
+                     0,
+                     &mhdr.num_buffers, sizeof mhdr.num_buffers);
     }
 
-    memset(buf, 0, hdrlen);
-    /* TODO: support mergeable buffers. */
-    if (hdrlen == 12)
-        hdr->num_buffers = 1;
-    len = vubr_backend_udp_recvbuf(dev, buf + hdrlen, buflen - hdrlen);
+    vu_queue_flush(dev, vq, i);
+    vu_queue_notify(dev, vq);
 
-    vubr_post_buffer(dev, rx_vq, buf, len + hdrlen);
+    free(elem);
 }
 
 static void
-vubr_kick_cb(int sock, void *ctx)
+vubr_receive_cb(int sock, void *ctx)
 {
-    VubrDev *dev = (VubrDev *) ctx;
-    eventfd_t kick_data;
-    ssize_t rc;
+    VubrDev *vubr = (VubrDev *)ctx;
 
-    rc = eventfd_read(sock, &kick_data);
-    if (rc == -1) {
-        vubr_die("eventfd_read()");
-    } else {
-        DPRINT("Got kick_data: %016"PRIx64"\n", kick_data);
-        vubr_process_avail(dev, &dev->vq[1]);
+    if (!vu_dispatch(&vubr->vudev)) {
+        fprintf(stderr, "Error while dispatching\n");
     }
 }
 
-static int
-vubr_none_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    DPRINT("Function %s() not implemented yet.\n", __func__);
-    return 0;
-}
+typedef struct WatchData {
+    VuDev *dev;
+    vu_watch_cb cb;
+    void *data;
+} WatchData;
 
-static int
-vubr_get_features_exec(VubrDev *dev, VhostUserMsg *vmsg)
+static void
+watch_cb(int sock, void *ctx)
 {
-    vmsg->payload.u64 =
-            ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
-             (1ULL << VHOST_F_LOG_ALL) |
-             (1ULL << VIRTIO_NET_F_GUEST_ANNOUNCE) |
-             (1ULL << VHOST_USER_F_PROTOCOL_FEATURES));
-
-    vmsg->size = sizeof(vmsg->payload.u64);
+    struct WatchData *wd = ctx;
 
-    DPRINT("Sending back to guest u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
-
-    /* Reply */
-    return 1;
+    wd->cb(wd->dev, VU_WATCH_IN, wd->data);
 }
 
-static int
-vubr_set_features_exec(VubrDev *dev, VhostUserMsg *vmsg)
+static void
+vubr_set_watch(VuDev *dev, int fd, int condition,
+               vu_watch_cb cb, void *data)
 {
-    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
-
-    dev->features = vmsg->payload.u64;
-    if ((dev->features & (1ULL << VIRTIO_F_VERSION_1)) ||
-        (dev->features & (1ULL << VIRTIO_NET_F_MRG_RXBUF))) {
-        dev->hdrlen = 12;
-    } else {
-        dev->hdrlen = 10;
-    }
+    VubrDev *vubr = container_of(dev, VubrDev, vudev);
+    static WatchData watches[FD_SETSIZE];
+    struct WatchData *wd = &watches[fd];
 
-    return 0;
-}
-
-static int
-vubr_set_owner_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    return 0;
+    wd->cb = cb;
+    wd->data = data;
+    wd->dev = dev;
+    dispatcher_add(&vubr->dispatcher, fd, wd, watch_cb);
 }
 
 static void
-vubr_close_log(VubrDev *dev)
+vubr_remove_watch(VuDev *dev, int fd)
 {
-    if (dev->log_table) {
-        if (munmap(dev->log_table, dev->log_size) != 0) {
-            vubr_die("munmap()");
-        }
+    VubrDev *vubr = container_of(dev, VubrDev, vudev);
 
-        dev->log_table = 0;
-    }
-    if (dev->log_call_fd != -1) {
-        close(dev->log_call_fd);
-        dev->log_call_fd = -1;
-    }
-}
-
-static int
-vubr_reset_device_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    vubr_close_log(dev);
-    dev->ready = 0;
-    dev->features = 0;
-    return 0;
+    dispatcher_remove(&vubr->dispatcher, fd);
 }
 
 static int
-vubr_set_mem_table_exec(VubrDev *dev, VhostUserMsg *vmsg)
+vubr_send_rarp_exec(VuDev *dev, VhostUserMsg *vmsg)
 {
-    int i;
-    VhostUserMemory *memory = &vmsg->payload.memory;
-    dev->nregions = memory->nregions;
-
-    DPRINT("Nregions: %d\n", memory->nregions);
-    for (i = 0; i < dev->nregions; i++) {
-        void *mmap_addr;
-        VhostUserMemoryRegion *msg_region = &memory->regions[i];
-        VubrDevRegion *dev_region = &dev->regions[i];
-
-        DPRINT("Region %d\n", i);
-        DPRINT("    guest_phys_addr: 0x%016"PRIx64"\n",
-               msg_region->guest_phys_addr);
-        DPRINT("    memory_size:     0x%016"PRIx64"\n",
-               msg_region->memory_size);
-        DPRINT("    userspace_addr   0x%016"PRIx64"\n",
-               msg_region->userspace_addr);
-        DPRINT("    mmap_offset      0x%016"PRIx64"\n",
-               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, and we use huge
-         * pages.  */
-        mmap_addr = mmap(0, dev_region->size + dev_region->mmap_offset,
-                         PROT_READ | PROT_WRITE, MAP_SHARED,
-                         vmsg->fds[i], 0);
-
-        if (mmap_addr == MAP_FAILED) {
-            vubr_die("mmap");
-        }
-        dev_region->mmap_addr = (uint64_t)(uintptr_t)mmap_addr;
-        DPRINT("    mmap_addr:       0x%016"PRIx64"\n", dev_region->mmap_addr);
-
-        close(vmsg->fds[i]);
-    }
-
+    DPRINT("Function %s() not implemented yet.\n", __func__);
     return 0;
 }
 
 static int
-vubr_set_log_base_exec(VubrDev *dev, VhostUserMsg *vmsg)
+vubr_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
 {
-    int fd;
-    uint64_t log_mmap_size, log_mmap_offset;
-    void *rc;
-
-    assert(vmsg->fd_num == 1);
-    fd = vmsg->fds[0];
-
-    assert(vmsg->size == sizeof(vmsg->payload.log));
-    log_mmap_offset = vmsg->payload.log.mmap_offset;
-    log_mmap_size = vmsg->payload.log.mmap_size;
-    DPRINT("Log mmap_offset: %"PRId64"\n", log_mmap_offset);
-    DPRINT("Log mmap_size:   %"PRId64"\n", log_mmap_size);
-
-    rc = mmap(0, log_mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
-              log_mmap_offset);
-    if (rc == MAP_FAILED) {
-        vubr_die("mmap");
+    switch (vmsg->request) {
+    case VHOST_USER_SEND_RARP:
+        *do_reply = vubr_send_rarp_exec(dev, vmsg);
+        return 1;
+    default:
+        /* let the library handle the rest */
+        return 0;
     }
-    dev->log_table = rc;
-    dev->log_size = log_mmap_size;
 
-    vmsg->size = sizeof(vmsg->payload.u64);
-    /* Reply */
-    return 1;
-}
-
-static int
-vubr_set_log_fd_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    assert(vmsg->fd_num == 1);
-    dev->log_call_fd = vmsg->fds[0];
-    DPRINT("Got log_call_fd: %d\n", vmsg->fds[0]);
     return 0;
 }
 
-static int
-vubr_set_vring_num_exec(VubrDev *dev, VhostUserMsg *vmsg)
+static void
+vubr_set_features(VuDev *dev, uint64_t features)
 {
-    unsigned int index = vmsg->payload.state.index;
-    unsigned int num = vmsg->payload.state.num;
-
-    DPRINT("State.index: %d\n", index);
-    DPRINT("State.num:   %d\n", num);
-    dev->vq[index].size = num;
-    return 0;
-}
+    VubrDev *vubr = container_of(dev, VubrDev, vudev);
 
-static int
-vubr_set_vring_addr_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    struct vhost_vring_addr *vra = &vmsg->payload.addr;
-    unsigned int index = vra->index;
-    VubrVirtq *vq = &dev->vq[index];
-
-    DPRINT("vhost_vring_addr:\n");
-    DPRINT("    index:  %d\n", vra->index);
-    DPRINT("    flags:  %d\n", vra->flags);
-    DPRINT("    desc_user_addr:   0x%016llx\n", vra->desc_user_addr);
-    DPRINT("    used_user_addr:   0x%016llx\n", vra->used_user_addr);
-    DPRINT("    avail_user_addr:  0x%016llx\n", vra->avail_user_addr);
-    DPRINT("    log_guest_addr:   0x%016llx\n", vra->log_guest_addr);
-
-    vq->desc = (struct vring_desc *)(uintptr_t)qva_to_va(dev, vra->desc_user_addr);
-    vq->used = (struct vring_used *)(uintptr_t)qva_to_va(dev, vra->used_user_addr);
-    vq->avail = (struct vring_avail *)(uintptr_t)qva_to_va(dev, vra->avail_user_addr);
-    vq->log_guest_addr = vra->log_guest_addr;
-
-    DPRINT("Setting virtq addresses:\n");
-    DPRINT("    vring_desc  at %p\n", vq->desc);
-    DPRINT("    vring_used  at %p\n", vq->used);
-    DPRINT("    vring_avail at %p\n", vq->avail);
-
-    vq->last_used_index = vq->used->idx;
-
-    if (vq->last_avail_index != vq->used->idx) {
-        DPRINT("Last avail index != used index: %d != %d, resuming",
-               vq->last_avail_index, vq->used->idx);
-        vq->last_avail_index = vq->used->idx;
+    if ((features & (1ULL << VIRTIO_F_VERSION_1)) ||
+        (features & (1ULL << VIRTIO_NET_F_MRG_RXBUF))) {
+        vubr->hdrlen = 12;
+    } else {
+        vubr->hdrlen = 10;
     }
-
-    return 0;
 }
 
-static int
-vubr_set_vring_base_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    unsigned int index = vmsg->payload.state.index;
-    unsigned int num = vmsg->payload.state.num;
-
-    DPRINT("State.index: %d\n", index);
-    DPRINT("State.num:   %d\n", num);
-    dev->vq[index].last_avail_index = num;
-
-    return 0;
-}
-
-static int
-vubr_get_vring_base_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    unsigned int index = vmsg->payload.state.index;
-
-    DPRINT("State.index: %d\n", index);
-    vmsg->payload.state.num = dev->vq[index].last_avail_index;
-    vmsg->size = sizeof(vmsg->payload.state);
-    /* FIXME: this is a work-around for a bug in QEMU enabling
-     * too early vrings. When protocol features are enabled,
-     * we have to respect * VHOST_USER_SET_VRING_ENABLE request. */
-    dev->ready = 0;
-
-    if (dev->vq[index].call_fd != -1) {
-        close(dev->vq[index].call_fd);
-        dispatcher_remove(&dev->dispatcher, dev->vq[index].call_fd);
-        dev->vq[index].call_fd = -1;
-    }
-    if (dev->vq[index].kick_fd != -1) {
-        close(dev->vq[index].kick_fd);
-        dispatcher_remove(&dev->dispatcher, dev->vq[index].kick_fd);
-        dev->vq[index].kick_fd = -1;
-    }
-
-    /* Reply */
-    return 1;
-}
-
-static int
-vubr_set_vring_kick_exec(VubrDev *dev, VhostUserMsg *vmsg)
+static uint64_t
+vubr_get_features(VuDev *dev)
 {
-    uint64_t u64_arg = vmsg->payload.u64;
-    int index = u64_arg & VHOST_USER_VRING_IDX_MASK;
-
-    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
-
-    assert((u64_arg & VHOST_USER_VRING_NOFD_MASK) == 0);
-    assert(vmsg->fd_num == 1);
-
-    if (dev->vq[index].kick_fd != -1) {
-        close(dev->vq[index].kick_fd);
-        dispatcher_remove(&dev->dispatcher, dev->vq[index].kick_fd);
-    }
-    dev->vq[index].kick_fd = vmsg->fds[0];
-    DPRINT("Got kick_fd: %d for vq: %d\n", vmsg->fds[0], index);
-
-    if (index % 2 == 1) {
-        /* TX queue. */
-        dispatcher_add(&dev->dispatcher, dev->vq[index].kick_fd,
-                       dev, vubr_kick_cb);
-
-        DPRINT("Waiting for kicks on fd: %d for vq: %d\n",
-               dev->vq[index].kick_fd, index);
-    }
-    /* We temporarily use this hack to determine that both TX and RX
-     * queues are set up and ready for processing.
-     * FIXME: we need to rely in VHOST_USER_SET_VRING_ENABLE and
-     * actual kicks. */
-    if (dev->vq[0].kick_fd != -1 &&
-        dev->vq[1].kick_fd != -1) {
-        dev->ready = 1;
-        DPRINT("vhost-user-bridge is ready for processing queues.\n");
-    }
-    return 0;
-
+    return 1ULL << VIRTIO_NET_F_GUEST_ANNOUNCE |
+        1ULL << VIRTIO_NET_F_MRG_RXBUF;
 }
 
-static int
-vubr_set_vring_call_exec(VubrDev *dev, VhostUserMsg *vmsg)
+static void
+vubr_queue_set_started(VuDev *dev, int qidx, bool started)
 {
-    uint64_t u64_arg = vmsg->payload.u64;
-    int index = u64_arg & VHOST_USER_VRING_IDX_MASK;
+    VuVirtq *vq = vu_get_queue(dev, qidx);
 
-    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
-    assert((u64_arg & VHOST_USER_VRING_NOFD_MASK) == 0);
-    assert(vmsg->fd_num == 1);
-
-    if (dev->vq[index].call_fd != -1) {
-        close(dev->vq[index].call_fd);
-        dispatcher_remove(&dev->dispatcher, dev->vq[index].call_fd);
+    if (qidx % 2 == 1) {
+        vu_set_queue_handler(dev, vq, started ? vubr_handle_tx : NULL);
     }
-    dev->vq[index].call_fd = vmsg->fds[0];
-    DPRINT("Got call_fd: %d for vq: %d\n", vmsg->fds[0], index);
-
-    return 0;
-}
-
-static int
-vubr_set_vring_err_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
-    return 0;
-}
-
-static int
-vubr_get_protocol_features_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    vmsg->payload.u64 = 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD;
-    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
-    vmsg->size = sizeof(vmsg->payload.u64);
-
-    /* Reply */
-    return 1;
 }
 
-static int
-vubr_set_protocol_features_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    /* FIXME: unimplented */
-    DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
-    return 0;
-}
-
-static int
-vubr_get_queue_num_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    DPRINT("Function %s() not implemented yet.\n", __func__);
-    return 0;
-}
-
-static int
-vubr_set_vring_enable_exec(VubrDev *dev, VhostUserMsg *vmsg)
+static void
+vubr_panic(VuDev *dev, const char *msg)
 {
-    unsigned int index = vmsg->payload.state.index;
-    unsigned int enable = vmsg->payload.state.num;
+    VubrDev *vubr = container_of(dev, VubrDev, vudev);
 
-    DPRINT("State.index: %d\n", index);
-    DPRINT("State.enable:   %d\n", enable);
-    dev->vq[index].enable = enable;
-    return 0;
-}
+    fprintf(stderr, "PANIC: %s\n", msg);
 
-static int
-vubr_send_rarp_exec(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    DPRINT("Function %s() not implemented yet.\n", __func__);
-    return 0;
+    dispatcher_remove(&vubr->dispatcher, dev->sock);
+    vubr->quit = 1;
 }
 
-static int
-vubr_execute_request(VubrDev *dev, VhostUserMsg *vmsg)
-{
-    /* Print out generic part of the request. */
-    DPRINT(
-           "==================   Vhost user message from QEMU   ==================\n");
-    DPRINT("Request: %s (%d)\n", vubr_request_str[vmsg->request],
-           vmsg->request);
-    DPRINT("Flags:   0x%x\n", vmsg->flags);
-    DPRINT("Size:    %d\n", vmsg->size);
-
-    if (vmsg->fd_num) {
-        int i;
-        DPRINT("Fds:");
-        for (i = 0; i < vmsg->fd_num; i++) {
-            DPRINT(" %d", vmsg->fds[i]);
-        }
-        DPRINT("\n");
-    }
-
-    switch (vmsg->request) {
-    case VHOST_USER_NONE:
-        return vubr_none_exec(dev, vmsg);
-    case VHOST_USER_GET_FEATURES:
-        return vubr_get_features_exec(dev, vmsg);
-    case VHOST_USER_SET_FEATURES:
-        return vubr_set_features_exec(dev, vmsg);
-    case VHOST_USER_SET_OWNER:
-        return vubr_set_owner_exec(dev, vmsg);
-    case VHOST_USER_RESET_OWNER:
-        return vubr_reset_device_exec(dev, vmsg);
-    case VHOST_USER_SET_MEM_TABLE:
-        return vubr_set_mem_table_exec(dev, vmsg);
-    case VHOST_USER_SET_LOG_BASE:
-        return vubr_set_log_base_exec(dev, vmsg);
-    case VHOST_USER_SET_LOG_FD:
-        return vubr_set_log_fd_exec(dev, vmsg);
-    case VHOST_USER_SET_VRING_NUM:
-        return vubr_set_vring_num_exec(dev, vmsg);
-    case VHOST_USER_SET_VRING_ADDR:
-        return vubr_set_vring_addr_exec(dev, vmsg);
-    case VHOST_USER_SET_VRING_BASE:
-        return vubr_set_vring_base_exec(dev, vmsg);
-    case VHOST_USER_GET_VRING_BASE:
-        return vubr_get_vring_base_exec(dev, vmsg);
-    case VHOST_USER_SET_VRING_KICK:
-        return vubr_set_vring_kick_exec(dev, vmsg);
-    case VHOST_USER_SET_VRING_CALL:
-        return vubr_set_vring_call_exec(dev, vmsg);
-    case VHOST_USER_SET_VRING_ERR:
-        return vubr_set_vring_err_exec(dev, vmsg);
-    case VHOST_USER_GET_PROTOCOL_FEATURES:
-        return vubr_get_protocol_features_exec(dev, vmsg);
-    case VHOST_USER_SET_PROTOCOL_FEATURES:
-        return vubr_set_protocol_features_exec(dev, vmsg);
-    case VHOST_USER_GET_QUEUE_NUM:
-        return vubr_get_queue_num_exec(dev, vmsg);
-    case VHOST_USER_SET_VRING_ENABLE:
-        return vubr_set_vring_enable_exec(dev, vmsg);
-    case VHOST_USER_SEND_RARP:
-        return vubr_send_rarp_exec(dev, vmsg);
-
-    case VHOST_USER_MAX:
-        assert(vmsg->request != VHOST_USER_MAX);
-    }
-    return 0;
-}
-
-static void
-vubr_receive_cb(int sock, void *ctx)
-{
-    VubrDev *dev = (VubrDev *) ctx;
-    VhostUserMsg vmsg;
-    int reply_requested;
-
-    vubr_message_read(sock, &vmsg);
-    reply_requested = vubr_execute_request(dev, &vmsg);
-    if (reply_requested) {
-        /* Set the version in the flags when sending the reply */
-        vmsg.flags &= ~VHOST_USER_VERSION_MASK;
-        vmsg.flags |= VHOST_USER_VERSION;
-        vmsg.flags |= VHOST_USER_REPLY_MASK;
-        vubr_message_write(sock, &vmsg);
-    }
-}
+static const VuDevIface vuiface = {
+    .get_features = vubr_get_features,
+    .set_features = vubr_set_features,
+    .process_msg = vubr_process_msg,
+    .queue_set_started = vubr_queue_set_started,
+};
 
 static void
 vubr_accept_cb(int sock, void *ctx)
@@ -1204,36 +479,26 @@ vubr_accept_cb(int sock, void *ctx)
         vubr_die("accept()");
     }
     DPRINT("Got connection from remote peer on sock %d\n", conn_fd);
+
+    vu_init(&dev->vudev,
+            conn_fd,
+            vubr_panic,
+            vubr_set_watch,
+            vubr_remove_watch,
+            &vuiface);
+
     dispatcher_add(&dev->dispatcher, conn_fd, ctx, vubr_receive_cb);
+    dispatcher_remove(&dev->dispatcher, sock);
 }
 
 static VubrDev *
 vubr_new(const char *path, bool client)
 {
     VubrDev *dev = (VubrDev *) calloc(1, sizeof(VubrDev));
-    dev->nregions = 0;
-    int i;
     struct sockaddr_un un;
     CallbackFunc cb;
     size_t len;
 
-    for (i = 0; i < MAX_NR_VIRTQUEUE; i++) {
-        dev->vq[i] = (VubrVirtq) {
-            .call_fd = -1, .kick_fd = -1,
-            .size = 0,
-            .last_avail_index = 0, .last_used_index = 0,
-            .desc = 0, .avail = 0, .used = 0,
-            .enable = 0,
-        };
-    }
-
-    /* Init log */
-    dev->log_call_fd = -1;
-    dev->log_size = 0;
-    dev->log_table = 0;
-    dev->ready = 0;
-    dev->features = 0;
-
     /* Get a UNIX socket. */
     dev->sock = socket(AF_UNIX, SOCK_STREAM, 0);
     if (dev->sock == -1) {
@@ -1261,10 +526,17 @@ vubr_new(const char *path, bool client)
         if (connect(dev->sock, (struct sockaddr *)&un, len) == -1) {
             vubr_die("connect");
         }
+        vu_init(&dev->vudev,
+                dev->sock,
+                vubr_panic,
+                vubr_set_watch,
+                vubr_remove_watch,
+                &vuiface);
         cb = vubr_receive_cb;
     }
 
     dispatcher_init(&dev->dispatcher);
+
     dispatcher_add(&dev->dispatcher, dev->sock, (void *)dev, cb);
 
     return dev;
@@ -1345,7 +617,7 @@ vubr_backend_udp_setup(VubrDev *dev,
 static void
 vubr_run(VubrDev *dev)
 {
-    while (1) {
+    while (!dev->quit) {
         /* timeout 200ms */
         dispatcher_wait(&dev->dispatcher, 200000);
         /* Here one can try polling strategy. */
@@ -1421,6 +693,9 @@ main(int argc, char *argv[])
 
     vubr_backend_udp_setup(dev, lhost, lport, rhost, rport);
     vubr_run(dev);
+
+    vu_deinit(&dev->vudev);
+
     return 0;
 
 out: