diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 2bce89129d..1ab4133769 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -252,8 +252,7 @@ static int vhost_net_start_one(struct vhost_net *net,
         file.fd = net->backend;
         for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
             const VhostOps *vhost_ops = net->dev.vhost_ops;
-            r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
-                                      &file);
+            r = vhost_ops->vhost_net_set_backend(&net->dev, &file);
             if (r < 0) {
                 r = -errno;
                 goto fail;
@@ -266,8 +265,7 @@ fail:
     if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
         while (file.index-- > 0) {
             const VhostOps *vhost_ops = net->dev.vhost_ops;
-            int r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
-                                          &file);
+            int r = vhost_ops->vhost_net_set_backend(&net->dev, &file);
             assert(r >= 0);
         }
     }
@@ -289,15 +287,13 @@ static void vhost_net_stop_one(struct vhost_net *net,
     if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
         for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
             const VhostOps *vhost_ops = net->dev.vhost_ops;
-            int r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
-                                          &file);
+            int r = vhost_ops->vhost_net_set_backend(&net->dev, &file);
             assert(r >= 0);
         }
     } else if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
         for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
             const VhostOps *vhost_ops = net->dev.vhost_ops;
-            int r = vhost_ops->vhost_call(&net->dev, VHOST_RESET_DEVICE,
-                                          NULL);
+            int r = vhost_ops->vhost_reset_device(&net->dev);
             assert(r >= 0);
         }
     }
@@ -428,8 +424,8 @@ int vhost_set_vring_enable(NetClientState *nc, int enable)
     VHostNetState *net = get_vhost_net(nc);
     const VhostOps *vhost_ops = net->dev.vhost_ops;
 
-    if (vhost_ops->vhost_backend_set_vring_enable) {
-        return vhost_ops->vhost_backend_set_vring_enable(&net->dev, enable);
+    if (vhost_ops->vhost_set_vring_enable) {
+        return vhost_ops->vhost_set_vring_enable(&net->dev, enable);
     }
 
     return 0;
diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index fb7983d9dc..00cdac62f9 100644
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -46,7 +46,7 @@ static int vhost_scsi_set_endpoint(VHostSCSI *s)
 
     memset(&backend, 0, sizeof(backend));
     pstrcpy(backend.vhost_wwpn, sizeof(backend.vhost_wwpn), vs->conf.wwpn);
-    ret = vhost_ops->vhost_call(&s->dev, VHOST_SCSI_SET_ENDPOINT, &backend);
+    ret = vhost_ops->vhost_scsi_set_endpoint(&s->dev, &backend);
     if (ret < 0) {
         return -errno;
     }
@@ -61,7 +61,7 @@ static void vhost_scsi_clear_endpoint(VHostSCSI *s)
 
     memset(&backend, 0, sizeof(backend));
     pstrcpy(backend.vhost_wwpn, sizeof(backend.vhost_wwpn), vs->conf.wwpn);
-    vhost_ops->vhost_call(&s->dev, VHOST_SCSI_CLEAR_ENDPOINT, &backend);
+    vhost_ops->vhost_scsi_clear_endpoint(&s->dev, &backend);
 }
 
 static int vhost_scsi_start(VHostSCSI *s)
@@ -77,8 +77,7 @@ static int vhost_scsi_start(VHostSCSI *s)
         return -ENOSYS;
     }
 
-    ret = vhost_ops->vhost_call(&s->dev,
-                                VHOST_SCSI_GET_ABI_VERSION, &abi_version);
+    ret = vhost_ops->vhost_scsi_get_abi_version(&s->dev, &abi_version);
     if (ret < 0) {
         return -errno;
     }
diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 5a2f1af137..1d5f684eb0 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -43,13 +43,6 @@ static int vhost_kernel_cleanup(struct vhost_dev *dev)
     return close(fd);
 }
 
-static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
-{
-    assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
-
-    return idx - dev->vq_index;
-}
-
 static int vhost_kernel_memslots_limit(struct vhost_dev *dev)
 {
     int limit = 64;
@@ -67,20 +60,135 @@ static int vhost_kernel_memslots_limit(struct vhost_dev *dev)
     return limit;
 }
 
-static int vhost_set_log_base(struct vhost_dev *dev, uint64_t base,
-                              struct vhost_log *log)
+static int vhost_kernel_net_set_backend(struct vhost_dev *dev,
+                                        struct vhost_vring_file *file)
+{
+    return vhost_kernel_call(dev, VHOST_NET_SET_BACKEND, file);
+}
+
+static int vhost_kernel_scsi_set_endpoint(struct vhost_dev *dev,
+                                          struct vhost_scsi_target *target)
+{
+    return vhost_kernel_call(dev, VHOST_SCSI_SET_ENDPOINT, target);
+}
+
+static int vhost_kernel_scsi_clear_endpoint(struct vhost_dev *dev,
+                                            struct vhost_scsi_target *target)
+{
+    return vhost_kernel_call(dev, VHOST_SCSI_CLEAR_ENDPOINT, target);
+}
+
+static int vhost_kernel_scsi_get_abi_version(struct vhost_dev *dev, int *version)
+{
+    return vhost_kernel_call(dev, VHOST_SCSI_GET_ABI_VERSION, version);
+}
+
+static int vhost_kernel_set_log_base(struct vhost_dev *dev, uint64_t base,
+                                     struct vhost_log *log)
 {
     return vhost_kernel_call(dev, VHOST_SET_LOG_BASE, &base);
 }
 
+static int vhost_kernel_set_mem_table(struct vhost_dev *dev,
+                                      struct vhost_memory *mem)
+{
+    return vhost_kernel_call(dev, VHOST_SET_MEM_TABLE, mem);
+}
+
+static int vhost_kernel_set_vring_addr(struct vhost_dev *dev,
+                                       struct vhost_vring_addr *addr)
+{
+    return vhost_kernel_call(dev, VHOST_SET_VRING_ADDR, addr);
+}
+
+static int vhost_kernel_set_vring_endian(struct vhost_dev *dev,
+                                         struct vhost_vring_state *ring)
+{
+    return vhost_kernel_call(dev, VHOST_SET_VRING_ENDIAN, ring);
+}
+
+static int vhost_kernel_set_vring_num(struct vhost_dev *dev,
+                                      struct vhost_vring_state *ring)
+{
+    return vhost_kernel_call(dev, VHOST_SET_VRING_NUM, ring);
+}
+
+static int vhost_kernel_set_vring_base(struct vhost_dev *dev,
+                                       struct vhost_vring_state *ring)
+{
+    return vhost_kernel_call(dev, VHOST_SET_VRING_BASE, ring);
+}
+
+static int vhost_kernel_get_vring_base(struct vhost_dev *dev,
+                                       struct vhost_vring_state *ring)
+{
+    return vhost_kernel_call(dev, VHOST_GET_VRING_BASE, ring);
+}
+
+static int vhost_kernel_set_vring_kick(struct vhost_dev *dev,
+                                       struct vhost_vring_file *file)
+{
+    return vhost_kernel_call(dev, VHOST_SET_VRING_KICK, file);
+}
+
+static int vhost_kernel_set_vring_call(struct vhost_dev *dev,
+                                       struct vhost_vring_file *file)
+{
+    return vhost_kernel_call(dev, VHOST_SET_VRING_CALL, file);
+}
+
+static int vhost_kernel_set_features(struct vhost_dev *dev,
+                                     uint64_t features)
+{
+    return vhost_kernel_call(dev, VHOST_SET_FEATURES, &features);
+}
+
+static int vhost_kernel_get_features(struct vhost_dev *dev,
+                                     uint64_t *features)
+{
+    return vhost_kernel_call(dev, VHOST_GET_FEATURES, features);
+}
+
+static int vhost_kernel_set_owner(struct vhost_dev *dev)
+{
+    return vhost_kernel_call(dev, VHOST_SET_OWNER, NULL);
+}
+
+static int vhost_kernel_reset_device(struct vhost_dev *dev)
+{
+    return vhost_kernel_call(dev, VHOST_RESET_DEVICE, NULL);
+}
+
+static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
+{
+    assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
+
+    return idx - dev->vq_index;
+}
+
 static const VhostOps kernel_ops = {
         .backend_type = VHOST_BACKEND_TYPE_KERNEL,
-        .vhost_call = vhost_kernel_call,
         .vhost_backend_init = vhost_kernel_init,
         .vhost_backend_cleanup = vhost_kernel_cleanup,
-        .vhost_backend_get_vq_index = vhost_kernel_get_vq_index,
         .vhost_backend_memslots_limit = vhost_kernel_memslots_limit,
-        .vhost_set_log_base = vhost_set_log_base,
+        .vhost_net_set_backend = vhost_kernel_net_set_backend,
+        .vhost_scsi_set_endpoint = vhost_kernel_scsi_set_endpoint,
+        .vhost_scsi_clear_endpoint = vhost_kernel_scsi_clear_endpoint,
+        .vhost_scsi_get_abi_version = vhost_kernel_scsi_get_abi_version,
+        .vhost_set_log_base = vhost_kernel_set_log_base,
+        .vhost_set_mem_table = vhost_kernel_set_mem_table,
+        .vhost_set_vring_addr = vhost_kernel_set_vring_addr,
+        .vhost_set_vring_endian = vhost_kernel_set_vring_endian,
+        .vhost_set_vring_num = vhost_kernel_set_vring_num,
+        .vhost_set_vring_base = vhost_kernel_set_vring_base,
+        .vhost_get_vring_base = vhost_kernel_get_vring_base,
+        .vhost_set_vring_kick = vhost_kernel_set_vring_kick,
+        .vhost_set_vring_call = vhost_kernel_set_vring_call,
+        .vhost_set_features = vhost_kernel_set_features,
+        .vhost_get_features = vhost_kernel_get_features,
+        .vhost_set_owner = vhost_kernel_set_owner,
+        .vhost_reset_device = vhost_kernel_reset_device,
+        .vhost_get_vq_index = vhost_kernel_get_vq_index,
 };
 
 int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index fb3aa40d59..16d8e80a2a 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -99,37 +99,6 @@ static bool ioeventfd_enabled(void)
     return kvm_enabled() && kvm_eventfds_enabled();
 }
 
-static unsigned long int ioctl_to_vhost_user_request[VHOST_USER_MAX] = {
-    -1,                     /* VHOST_USER_NONE */
-    VHOST_GET_FEATURES,     /* VHOST_USER_GET_FEATURES */
-    VHOST_SET_FEATURES,     /* VHOST_USER_SET_FEATURES */
-    VHOST_SET_OWNER,        /* VHOST_USER_SET_OWNER */
-    VHOST_RESET_DEVICE,      /* VHOST_USER_RESET_DEVICE */
-    VHOST_SET_MEM_TABLE,    /* VHOST_USER_SET_MEM_TABLE */
-    VHOST_SET_LOG_BASE,     /* VHOST_USER_SET_LOG_BASE */
-    VHOST_SET_LOG_FD,       /* VHOST_USER_SET_LOG_FD */
-    VHOST_SET_VRING_NUM,    /* VHOST_USER_SET_VRING_NUM */
-    VHOST_SET_VRING_ADDR,   /* VHOST_USER_SET_VRING_ADDR */
-    VHOST_SET_VRING_BASE,   /* VHOST_USER_SET_VRING_BASE */
-    VHOST_GET_VRING_BASE,   /* VHOST_USER_GET_VRING_BASE */
-    VHOST_SET_VRING_KICK,   /* VHOST_USER_SET_VRING_KICK */
-    VHOST_SET_VRING_CALL,   /* VHOST_USER_SET_VRING_CALL */
-    VHOST_SET_VRING_ERR     /* VHOST_USER_SET_VRING_ERR */
-};
-
-static VhostUserRequest vhost_user_request_translate(unsigned long int request)
-{
-    VhostUserRequest idx;
-
-    for (idx = 0; idx < VHOST_USER_MAX; idx++) {
-        if (ioctl_to_vhost_user_request[idx] == request) {
-            break;
-        }
-    }
-
-    return (idx == VHOST_USER_MAX) ? VHOST_USER_NONE : idx;
-}
-
 static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg)
 {
     CharDriverState *chr = dev->opaque;
@@ -176,20 +145,6 @@ fail:
     return -1;
 }
 
-static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
-                            int *fds, int fd_num)
-{
-    CharDriverState *chr = dev->opaque;
-    int size = VHOST_USER_HDR_SIZE + msg->size;
-
-    if (fd_num) {
-        qemu_chr_fe_set_msgfds(chr, fds, fd_num);
-    }
-
-    return qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size) == size ?
-            0 : -1;
-}
-
 static bool vhost_user_one_time_request(VhostUserRequest request)
 {
     switch (request) {
@@ -203,173 +158,32 @@ static bool vhost_user_one_time_request(VhostUserRequest request)
     }
 }
 
-static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
-        void *arg)
+/* most non-init callers ignore the error */
+static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
+                            int *fds, int fd_num)
 {
-    VhostUserMsg msg;
-    VhostUserRequest msg_request;
-    struct vhost_vring_file *file = 0;
-    int need_reply = 0;
-    int fds[VHOST_MEMORY_MAX_NREGIONS];
-    int i, fd;
-    size_t fd_num = 0;
-
-    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
-
-    /* only translate vhost ioctl requests */
-    if (request > VHOST_USER_MAX) {
-        msg_request = vhost_user_request_translate(request);
-    } else {
-        msg_request = request;
-    }
+    CharDriverState *chr = dev->opaque;
+    int size = VHOST_USER_HDR_SIZE + msg->size;
 
     /*
      * For non-vring specific requests, like VHOST_USER_SET_MEM_TABLE,
      * we just need send it once in the first time. For later such
      * request, we just ignore it.
      */
-    if (vhost_user_one_time_request(msg_request) && dev->vq_index != 0) {
+    if (vhost_user_one_time_request(msg->request) && dev->vq_index != 0) {
         return 0;
     }
 
-    msg.request = msg_request;
-    msg.flags = VHOST_USER_VERSION;
-    msg.size = 0;
-
-    switch (msg_request) {
-    case VHOST_USER_GET_FEATURES:
-    case VHOST_USER_GET_PROTOCOL_FEATURES:
-    case VHOST_USER_GET_QUEUE_NUM:
-        need_reply = 1;
-        break;
-
-    case VHOST_USER_SET_FEATURES:
-    case VHOST_USER_SET_PROTOCOL_FEATURES:
-        msg.u64 = *((__u64 *) arg);
-        msg.size = sizeof(m.u64);
-        break;
-
-    case VHOST_USER_SET_OWNER:
-    case VHOST_USER_RESET_DEVICE:
-        break;
-
-    case VHOST_USER_SET_MEM_TABLE:
-        for (i = 0; i < dev->mem->nregions; ++i) {
-            struct vhost_memory_region *reg = dev->mem->regions + i;
-            ram_addr_t ram_addr;
-
-            assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
-            qemu_ram_addr_from_host((void *)(uintptr_t)reg->userspace_addr, &ram_addr);
-            fd = qemu_get_ram_fd(ram_addr);
-            if (fd > 0) {
-                msg.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
-                msg.memory.regions[fd_num].memory_size  = reg->memory_size;
-                msg.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr;
-                msg.memory.regions[fd_num].mmap_offset = reg->userspace_addr -
-                    (uintptr_t) qemu_get_ram_block_host_ptr(ram_addr);
-                assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
-                fds[fd_num++] = fd;
-            }
-        }
-
-        msg.memory.nregions = fd_num;
-
-        if (!fd_num) {
-            error_report("Failed initializing vhost-user memory map, "
-                    "consider using -object memory-backend-file share=on");
-            return -1;
-        }
-
-        msg.size = sizeof(m.memory.nregions);
-        msg.size += sizeof(m.memory.padding);
-        msg.size += fd_num * sizeof(VhostUserMemoryRegion);
-
-        break;
-
-    case VHOST_USER_SET_LOG_FD:
-        fds[fd_num++] = *((int *) arg);
-        break;
-
-    case VHOST_USER_SET_VRING_NUM:
-    case VHOST_USER_SET_VRING_BASE:
-    case VHOST_USER_SET_VRING_ENABLE:
-        memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
-        msg.size = sizeof(m.state);
-        break;
-
-    case VHOST_USER_GET_VRING_BASE:
-        memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
-        msg.size = sizeof(m.state);
-        need_reply = 1;
-        break;
-
-    case VHOST_USER_SET_VRING_ADDR:
-        memcpy(&msg.addr, arg, sizeof(struct vhost_vring_addr));
-        msg.size = sizeof(m.addr);
-        break;
-
-    case VHOST_USER_SET_VRING_KICK:
-    case VHOST_USER_SET_VRING_CALL:
-    case VHOST_USER_SET_VRING_ERR:
-        file = arg;
-        msg.u64 = file->index & VHOST_USER_VRING_IDX_MASK;
-        msg.size = sizeof(m.u64);
-        if (ioeventfd_enabled() && file->fd > 0) {
-            fds[fd_num++] = file->fd;
-        } else {
-            msg.u64 |= VHOST_USER_VRING_NOFD_MASK;
-        }
-        break;
-    default:
-        error_report("vhost-user trying to send unhandled ioctl");
-        return -1;
-        break;
+    if (fd_num) {
+        qemu_chr_fe_set_msgfds(chr, fds, fd_num);
     }
 
-    if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
-        return 0;
-    }
-
-    if (need_reply) {
-        if (vhost_user_read(dev, &msg) < 0) {
-            return 0;
-        }
-
-        if (msg_request != msg.request) {
-            error_report("Received unexpected msg type."
-                    " Expected %d received %d", msg_request, msg.request);
-            return -1;
-        }
-
-        switch (msg_request) {
-        case VHOST_USER_GET_FEATURES:
-        case VHOST_USER_GET_PROTOCOL_FEATURES:
-        case VHOST_USER_GET_QUEUE_NUM:
-            if (msg.size != sizeof(m.u64)) {
-                error_report("Received bad msg size.");
-                return -1;
-            }
-            *((__u64 *) arg) = msg.u64;
-            break;
-        case VHOST_USER_GET_VRING_BASE:
-            if (msg.size != sizeof(m.state)) {
-                error_report("Received bad msg size.");
-                return -1;
-            }
-            memcpy(arg, &msg.state, sizeof(struct vhost_vring_state));
-            break;
-        default:
-            error_report("Received unexpected msg type.");
-            return -1;
-            break;
-        }
-    }
-
-    return 0;
+    return qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size) == size ?
+            0 : -1;
 }
 
-static int vhost_set_log_base(struct vhost_dev *dev, uint64_t base,
-                              struct vhost_log *log)
+static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
+                                   struct vhost_log *log)
 {
     int fds[VHOST_MEMORY_MAX_NREGIONS];
     size_t fd_num = 0;
@@ -405,16 +219,284 @@ static int vhost_set_log_base(struct vhost_dev *dev, uint64_t base,
     return 0;
 }
 
+static int vhost_user_set_mem_table(struct vhost_dev *dev,
+                                    struct vhost_memory *mem)
+{
+    int fds[VHOST_MEMORY_MAX_NREGIONS];
+    int i, fd;
+    size_t fd_num = 0;
+    VhostUserMsg msg = {
+        .request = VHOST_USER_SET_MEM_TABLE,
+        .flags = VHOST_USER_VERSION,
+    };
+
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        ram_addr_t ram_addr;
+
+        assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
+        qemu_ram_addr_from_host((void *)(uintptr_t)reg->userspace_addr,
+                                &ram_addr);
+        fd = qemu_get_ram_fd(ram_addr);
+        if (fd > 0) {
+            msg.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
+            msg.memory.regions[fd_num].memory_size  = reg->memory_size;
+            msg.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr;
+            msg.memory.regions[fd_num].mmap_offset = reg->userspace_addr -
+                (uintptr_t) qemu_get_ram_block_host_ptr(ram_addr);
+            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
+            fds[fd_num++] = fd;
+        }
+    }
+
+    msg.memory.nregions = fd_num;
+
+    if (!fd_num) {
+        error_report("Failed initializing vhost-user memory map, "
+                     "consider using -object memory-backend-file share=on");
+        return -1;
+    }
+
+    msg.size = sizeof(m.memory.nregions);
+    msg.size += sizeof(m.memory.padding);
+    msg.size += fd_num * sizeof(VhostUserMemoryRegion);
+
+    vhost_user_write(dev, &msg, fds, fd_num);
+
+    return 0;
+}
+
+static int vhost_user_set_vring_addr(struct vhost_dev *dev,
+                                     struct vhost_vring_addr *addr)
+{
+    VhostUserMsg msg = {
+        .request = VHOST_USER_SET_VRING_ADDR,
+        .flags = VHOST_USER_VERSION,
+        .addr = *addr,
+        .size = sizeof(*addr),
+    };
+
+    vhost_user_write(dev, &msg, NULL, 0);
+
+    return 0;
+}
+
+static int vhost_user_set_vring_endian(struct vhost_dev *dev,
+                                       struct vhost_vring_state *ring)
+{
+    error_report("vhost-user trying to send unhandled ioctl");
+    return -1;
+}
+
+static int vhost_set_vring(struct vhost_dev *dev,
+                           unsigned long int request,
+                           struct vhost_vring_state *ring)
+{
+    VhostUserMsg msg = {
+        .request = request,
+        .flags = VHOST_USER_VERSION,
+        .state = *ring,
+        .size = sizeof(*ring),
+    };
+
+    vhost_user_write(dev, &msg, NULL, 0);
+
+    return 0;
+}
+
+static int vhost_user_set_vring_num(struct vhost_dev *dev,
+                                    struct vhost_vring_state *ring)
+{
+    return vhost_set_vring(dev, VHOST_USER_SET_VRING_NUM, ring);
+}
+
+static int vhost_user_set_vring_base(struct vhost_dev *dev,
+                                     struct vhost_vring_state *ring)
+{
+    return vhost_set_vring(dev, VHOST_USER_SET_VRING_BASE, ring);
+}
+
+static int vhost_user_set_vring_enable(struct vhost_dev *dev, int enable)
+{
+    struct vhost_vring_state state = {
+        .index = dev->vq_index,
+        .num   = enable,
+    };
+
+    if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ))) {
+        return -1;
+    }
+
+    return vhost_set_vring(dev, VHOST_USER_SET_VRING_ENABLE, &state);
+}
+
+
+static int vhost_user_get_vring_base(struct vhost_dev *dev,
+                                     struct vhost_vring_state *ring)
+{
+    VhostUserMsg msg = {
+        .request = VHOST_USER_GET_VRING_BASE,
+        .flags = VHOST_USER_VERSION,
+        .state = *ring,
+        .size = sizeof(*ring),
+    };
+
+    vhost_user_write(dev, &msg, NULL, 0);
+
+    if (vhost_user_read(dev, &msg) < 0) {
+        return 0;
+    }
+
+    if (msg.request != VHOST_USER_GET_VRING_BASE) {
+        error_report("Received unexpected msg type. Expected %d received %d",
+                     VHOST_USER_GET_VRING_BASE, msg.request);
+        return -1;
+    }
+
+    if (msg.size != sizeof(m.state)) {
+        error_report("Received bad msg size.");
+        return -1;
+    }
+
+    *ring = msg.state;
+
+    return 0;
+}
+
+static int vhost_set_vring_file(struct vhost_dev *dev,
+                                VhostUserRequest request,
+                                struct vhost_vring_file *file)
+{
+    int fds[VHOST_MEMORY_MAX_NREGIONS];
+    size_t fd_num = 0;
+    VhostUserMsg msg = {
+        .request = request,
+        .flags = VHOST_USER_VERSION,
+        .u64 = file->index & VHOST_USER_VRING_IDX_MASK,
+        .size = sizeof(m.u64),
+    };
+
+    if (ioeventfd_enabled() && file->fd > 0) {
+        fds[fd_num++] = file->fd;
+    } else {
+        msg.u64 |= VHOST_USER_VRING_NOFD_MASK;
+    }
+
+    vhost_user_write(dev, &msg, fds, fd_num);
+
+    return 0;
+}
+
+static int vhost_user_set_vring_kick(struct vhost_dev *dev,
+                                     struct vhost_vring_file *file)
+{
+    return vhost_set_vring_file(dev, VHOST_USER_SET_VRING_KICK, file);
+}
+
+static int vhost_user_set_vring_call(struct vhost_dev *dev,
+                                     struct vhost_vring_file *file)
+{
+    return vhost_set_vring_file(dev, VHOST_USER_SET_VRING_CALL, file);
+}
+
+static int vhost_user_set_u64(struct vhost_dev *dev, int request, uint64_t u64)
+{
+    VhostUserMsg msg = {
+        .request = request,
+        .flags = VHOST_USER_VERSION,
+        .u64 = u64,
+        .size = sizeof(m.u64),
+    };
+
+    vhost_user_write(dev, &msg, NULL, 0);
+
+    return 0;
+}
+
+static int vhost_user_set_features(struct vhost_dev *dev,
+                                   uint64_t features)
+{
+    return vhost_user_set_u64(dev, VHOST_USER_SET_FEATURES, features);
+}
+
+static int vhost_user_set_protocol_features(struct vhost_dev *dev,
+                                            uint64_t features)
+{
+    return vhost_user_set_u64(dev, VHOST_USER_SET_PROTOCOL_FEATURES, features);
+}
+
+static int vhost_user_get_u64(struct vhost_dev *dev, int request, uint64_t *u64)
+{
+    VhostUserMsg msg = {
+        .request = request,
+        .flags = VHOST_USER_VERSION,
+    };
+
+    if (vhost_user_one_time_request(request) && dev->vq_index != 0) {
+        return 0;
+    }
+
+    vhost_user_write(dev, &msg, NULL, 0);
+
+    if (vhost_user_read(dev, &msg) < 0) {
+        return 0;
+    }
+
+    if (msg.request != request) {
+        error_report("Received unexpected msg type. Expected %d received %d",
+                     request, msg.request);
+        return -1;
+    }
+
+    if (msg.size != sizeof(m.u64)) {
+        error_report("Received bad msg size.");
+        return -1;
+    }
+
+    *u64 = msg.u64;
+
+    return 0;
+}
+
+static int vhost_user_get_features(struct vhost_dev *dev, uint64_t *features)
+{
+    return vhost_user_get_u64(dev, VHOST_USER_GET_FEATURES, features);
+}
+
+static int vhost_user_set_owner(struct vhost_dev *dev)
+{
+    VhostUserMsg msg = {
+        .request = VHOST_USER_SET_OWNER,
+        .flags = VHOST_USER_VERSION,
+    };
+
+    vhost_user_write(dev, &msg, NULL, 0);
+
+    return 0;
+}
+
+static int vhost_user_reset_device(struct vhost_dev *dev)
+{
+    VhostUserMsg msg = {
+        .request = VHOST_USER_RESET_DEVICE,
+        .flags = VHOST_USER_VERSION,
+    };
+
+    vhost_user_write(dev, &msg, NULL, 0);
+
+    return 0;
+}
+
 static int vhost_user_init(struct vhost_dev *dev, void *opaque)
 {
-    unsigned long long features;
+    uint64_t features;
     int err;
 
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 
     dev->opaque = opaque;
 
-    err = vhost_user_call(dev, VHOST_USER_GET_FEATURES, &features);
+    err = vhost_user_get_features(dev, &features);
     if (err < 0) {
         return err;
     }
@@ -422,21 +504,22 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
     if (virtio_has_feature(features, VHOST_USER_F_PROTOCOL_FEATURES)) {
         dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
 
-        err = vhost_user_call(dev, VHOST_USER_GET_PROTOCOL_FEATURES, &features);
+        err = vhost_user_get_u64(dev, VHOST_USER_GET_PROTOCOL_FEATURES,
+                                 &features);
         if (err < 0) {
             return err;
         }
 
         dev->protocol_features = features & VHOST_USER_PROTOCOL_FEATURE_MASK;
-        err = vhost_user_call(dev, VHOST_USER_SET_PROTOCOL_FEATURES,
-                              &dev->protocol_features);
+        err = vhost_user_set_protocol_features(dev, dev->protocol_features);
         if (err < 0) {
             return err;
         }
 
         /* query the max queues we support if backend supports Multiple Queue */
         if (dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ)) {
-            err = vhost_user_call(dev, VHOST_USER_GET_QUEUE_NUM, &dev->max_queues);
+            err = vhost_user_get_u64(dev, VHOST_USER_GET_QUEUE_NUM,
+                                     &dev->max_queues);
             if (err < 0) {
                 return err;
             }
@@ -454,22 +537,6 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
     return 0;
 }
 
-static int vhost_user_set_vring_enable(struct vhost_dev *dev, int enable)
-{
-    struct vhost_vring_state state = {
-        .index = dev->vq_index,
-        .num   = enable,
-    };
-
-    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
-
-    if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ))) {
-        return -1;
-    }
-
-    return vhost_user_call(dev, VHOST_USER_SET_VRING_ENABLE, &state);
-}
-
 static int vhost_user_cleanup(struct vhost_dev *dev)
 {
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
@@ -501,12 +568,23 @@ static bool vhost_user_requires_shm_log(struct vhost_dev *dev)
 
 const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
-        .vhost_call = vhost_user_call,
         .vhost_backend_init = vhost_user_init,
         .vhost_backend_cleanup = vhost_user_cleanup,
-        .vhost_backend_get_vq_index = vhost_user_get_vq_index,
-        .vhost_backend_set_vring_enable = vhost_user_set_vring_enable,
         .vhost_backend_memslots_limit = vhost_user_memslots_limit,
-        .vhost_set_log_base = vhost_set_log_base,
+        .vhost_set_log_base = vhost_user_set_log_base,
+        .vhost_set_mem_table = vhost_user_set_mem_table,
+        .vhost_set_vring_addr = vhost_user_set_vring_addr,
+        .vhost_set_vring_endian = vhost_user_set_vring_endian,
+        .vhost_set_vring_num = vhost_user_set_vring_num,
+        .vhost_set_vring_base = vhost_user_set_vring_base,
+        .vhost_get_vring_base = vhost_user_get_vring_base,
+        .vhost_set_vring_kick = vhost_user_set_vring_kick,
+        .vhost_set_vring_call = vhost_user_set_vring_call,
+        .vhost_set_features = vhost_user_set_features,
+        .vhost_get_features = vhost_user_get_features,
+        .vhost_set_owner = vhost_user_set_owner,
+        .vhost_reset_device = vhost_user_reset_device,
+        .vhost_get_vq_index = vhost_user_get_vq_index,
+        .vhost_set_vring_enable = vhost_user_set_vring_enable,
         .vhost_requires_shm_log = vhost_user_requires_shm_log,
 };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index a553256081..2e78e4b706 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -555,7 +555,7 @@ static void vhost_commit(MemoryListener *listener)
     }
 
     if (!dev->log_enabled) {
-        r = dev->vhost_ops->vhost_call(dev, VHOST_SET_MEM_TABLE, dev->mem);
+        r = dev->vhost_ops->vhost_set_mem_table(dev, dev->mem);
         assert(r >= 0);
         dev->memory_changed = false;
         return;
@@ -568,7 +568,7 @@ static void vhost_commit(MemoryListener *listener)
     if (dev->log_size < log_size) {
         vhost_dev_log_resize(dev, log_size + VHOST_LOG_BUFFER);
     }
-    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_MEM_TABLE, dev->mem);
+    r = dev->vhost_ops->vhost_set_mem_table(dev, dev->mem);
     assert(r >= 0);
     /* To log less, can only decrease log size after table update. */
     if (dev->log_size > log_size + VHOST_LOG_BUFFER) {
@@ -636,7 +636,7 @@ static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
         .log_guest_addr = vq->used_phys,
         .flags = enable_log ? (1 << VHOST_VRING_F_LOG) : 0,
     };
-    int r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_ADDR, &addr);
+    int r = dev->vhost_ops->vhost_set_vring_addr(dev, &addr);
     if (r < 0) {
         return -errno;
     }
@@ -650,7 +650,7 @@ static int vhost_dev_set_features(struct vhost_dev *dev, bool enable_log)
     if (enable_log) {
         features |= 0x1ULL << VHOST_F_LOG_ALL;
     }
-    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_FEATURES, &features);
+    r = dev->vhost_ops->vhost_set_features(dev, features);
     return r < 0 ? -errno : 0;
 }
 
@@ -755,7 +755,7 @@ static int vhost_virtqueue_set_vring_endian_legacy(struct vhost_dev *dev,
         .num = is_big_endian
     };
 
-    if (!dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_ENDIAN, &s)) {
+    if (!dev->vhost_ops->vhost_set_vring_endian(dev, &s)) {
         return 0;
     }
 
@@ -774,7 +774,7 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
 {
     hwaddr s, l, a;
     int r;
-    int vhost_vq_index = dev->vhost_ops->vhost_backend_get_vq_index(dev, idx);
+    int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, idx);
     struct vhost_vring_file file = {
         .index = vhost_vq_index
     };
@@ -785,13 +785,13 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
 
 
     vq->num = state.num = virtio_queue_get_num(vdev, idx);
-    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_NUM, &state);
+    r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
     if (r) {
         return -errno;
     }
 
     state.num = virtio_queue_get_last_avail_idx(vdev, idx);
-    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_BASE, &state);
+    r = dev->vhost_ops->vhost_set_vring_base(dev, &state);
     if (r) {
         return -errno;
     }
@@ -843,7 +843,7 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
     }
 
     file.fd = event_notifier_get_fd(virtio_queue_get_host_notifier(vvq));
-    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_KICK, &file);
+    r = dev->vhost_ops->vhost_set_vring_kick(dev, &file);
     if (r) {
         r = -errno;
         goto fail_kick;
@@ -876,13 +876,13 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
                                     struct vhost_virtqueue *vq,
                                     unsigned idx)
 {
-    int vhost_vq_index = dev->vhost_ops->vhost_backend_get_vq_index(dev, idx);
+    int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, idx);
     struct vhost_vring_state state = {
         .index = vhost_vq_index,
     };
     int r;
 
-    r = dev->vhost_ops->vhost_call(dev, VHOST_GET_VRING_BASE, &state);
+    r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
     if (r < 0) {
         fprintf(stderr, "vhost VQ %d ring restore failed: %d\n", idx, r);
         fflush(stderr);
@@ -929,7 +929,7 @@ static void vhost_eventfd_del(MemoryListener *listener,
 static int vhost_virtqueue_init(struct vhost_dev *dev,
                                 struct vhost_virtqueue *vq, int n)
 {
-    int vhost_vq_index = dev->vhost_ops->vhost_backend_get_vq_index(dev, n);
+    int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, n);
     struct vhost_vring_file file = {
         .index = vhost_vq_index,
     };
@@ -939,7 +939,7 @@ static int vhost_virtqueue_init(struct vhost_dev *dev,
     }
 
     file.fd = event_notifier_get_fd(&vq->masked_notifier);
-    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_CALL, &file);
+    r = dev->vhost_ops->vhost_set_vring_call(dev, &file);
     if (r) {
         r = -errno;
         goto fail_call;
@@ -981,12 +981,12 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     }
     QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
 
-    r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_OWNER, NULL);
+    r = hdev->vhost_ops->vhost_set_owner(hdev);
     if (r < 0) {
         goto fail;
     }
 
-    r = hdev->vhost_ops->vhost_call(hdev, VHOST_GET_FEATURES, &features);
+    r = hdev->vhost_ops->vhost_get_features(hdev, &features);
     if (r < 0) {
         goto fail;
     }
@@ -1147,8 +1147,8 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
         file.fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq));
     }
 
-    file.index = hdev->vhost_ops->vhost_backend_get_vq_index(hdev, n);
-    r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_VRING_CALL, &file);
+    file.index = hdev->vhost_ops->vhost_get_vq_index(hdev, n);
+    r = hdev->vhost_ops->vhost_set_vring_call(hdev, &file);
     assert(r >= 0);
 }
 
@@ -1190,7 +1190,7 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
     if (r < 0) {
         goto fail_features;
     }
-    r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_MEM_TABLE, hdev->mem);
+    r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
     if (r < 0) {
         r = -errno;
         goto fail_mem;
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index 375625f5fb..ad1948101d 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -22,28 +22,77 @@ typedef enum VhostBackendType {
 
 struct vhost_dev;
 struct vhost_log;
+struct vhost_memory;
+struct vhost_vring_file;
+struct vhost_vring_state;
+struct vhost_vring_addr;
+struct vhost_scsi_target;
 
-typedef int (*vhost_call)(struct vhost_dev *dev, unsigned long int request,
-             void *arg);
 typedef int (*vhost_backend_init)(struct vhost_dev *dev, void *opaque);
 typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
-typedef int (*vhost_backend_get_vq_index)(struct vhost_dev *dev, int idx);
-typedef int (*vhost_backend_set_vring_enable)(struct vhost_dev *dev, int enable);
 typedef int (*vhost_backend_memslots_limit)(struct vhost_dev *dev);
 
+typedef int (*vhost_net_set_backend_op)(struct vhost_dev *dev,
+                                struct vhost_vring_file *file);
+typedef int (*vhost_scsi_set_endpoint_op)(struct vhost_dev *dev,
+                                  struct vhost_scsi_target *target);
+typedef int (*vhost_scsi_clear_endpoint_op)(struct vhost_dev *dev,
+                                    struct vhost_scsi_target *target);
+typedef int (*vhost_scsi_get_abi_version_op)(struct vhost_dev *dev,
+                                             int *version);
 typedef int (*vhost_set_log_base_op)(struct vhost_dev *dev, uint64_t base,
                                      struct vhost_log *log);
+typedef int (*vhost_set_mem_table_op)(struct vhost_dev *dev,
+                                      struct vhost_memory *mem);
+typedef int (*vhost_set_vring_addr_op)(struct vhost_dev *dev,
+                                       struct vhost_vring_addr *addr);
+typedef int (*vhost_set_vring_endian_op)(struct vhost_dev *dev,
+                                         struct vhost_vring_state *ring);
+typedef int (*vhost_set_vring_num_op)(struct vhost_dev *dev,
+                                      struct vhost_vring_state *ring);
+typedef int (*vhost_set_vring_base_op)(struct vhost_dev *dev,
+                                       struct vhost_vring_state *ring);
+typedef int (*vhost_get_vring_base_op)(struct vhost_dev *dev,
+                                       struct vhost_vring_state *ring);
+typedef int (*vhost_set_vring_kick_op)(struct vhost_dev *dev,
+                                       struct vhost_vring_file *file);
+typedef int (*vhost_set_vring_call_op)(struct vhost_dev *dev,
+                                       struct vhost_vring_file *file);
+typedef int (*vhost_set_features_op)(struct vhost_dev *dev,
+                                     uint64_t features);
+typedef int (*vhost_get_features_op)(struct vhost_dev *dev,
+                                     uint64_t *features);
+typedef int (*vhost_set_owner_op)(struct vhost_dev *dev);
+typedef int (*vhost_reset_device_op)(struct vhost_dev *dev);
+typedef int (*vhost_get_vq_index_op)(struct vhost_dev *dev, int idx);
+typedef int (*vhost_set_vring_enable_op)(struct vhost_dev *dev,
+                                         int enable);
 typedef bool (*vhost_requires_shm_log_op)(struct vhost_dev *dev);
 
 typedef struct VhostOps {
     VhostBackendType backend_type;
-    vhost_call vhost_call;
     vhost_backend_init vhost_backend_init;
     vhost_backend_cleanup vhost_backend_cleanup;
-    vhost_backend_get_vq_index vhost_backend_get_vq_index;
-    vhost_backend_set_vring_enable vhost_backend_set_vring_enable;
     vhost_backend_memslots_limit vhost_backend_memslots_limit;
+    vhost_net_set_backend_op vhost_net_set_backend;
+    vhost_scsi_set_endpoint_op vhost_scsi_set_endpoint;
+    vhost_scsi_clear_endpoint_op vhost_scsi_clear_endpoint;
+    vhost_scsi_get_abi_version_op vhost_scsi_get_abi_version;
     vhost_set_log_base_op vhost_set_log_base;
+    vhost_set_mem_table_op vhost_set_mem_table;
+    vhost_set_vring_addr_op vhost_set_vring_addr;
+    vhost_set_vring_endian_op vhost_set_vring_endian;
+    vhost_set_vring_num_op vhost_set_vring_num;
+    vhost_set_vring_base_op vhost_set_vring_base;
+    vhost_get_vring_base_op vhost_get_vring_base;
+    vhost_set_vring_kick_op vhost_set_vring_kick;
+    vhost_set_vring_call_op vhost_set_vring_call;
+    vhost_set_features_op vhost_set_features;
+    vhost_get_features_op vhost_get_features;
+    vhost_set_owner_op vhost_set_owner;
+    vhost_reset_device_op vhost_reset_device;
+    vhost_get_vq_index_op vhost_get_vq_index;
+    vhost_set_vring_enable_op vhost_set_vring_enable;
     vhost_requires_shm_log_op vhost_requires_shm_log;
 } VhostOps;
 
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 6bf759f5c7..7437fd476a 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -45,14 +45,14 @@ struct vhost_dev {
     int nvqs;
     /* the first virtqueue which would be used by this vhost dev */
     int vq_index;
-    unsigned long long features;
-    unsigned long long acked_features;
-    unsigned long long backend_features;
-    unsigned long long protocol_features;
-    unsigned long long max_queues;
+    uint64_t features;
+    uint64_t acked_features;
+    uint64_t backend_features;
+    uint64_t protocol_features;
+    uint64_t max_queues;
     bool started;
     bool log_enabled;
-    unsigned long long log_size;
+    uint64_t log_size;
     Error *migration_blocker;
     bool memory_changed;
     hwaddr mem_changed_start_addr;