[Qemu-devel] [PATCH v7 1/4] cryptodev: add vhost-user as a new cryptodev backend

[Jay Zhou <jianjay.zhou@huawei.com>]

From: Gonglei <arei.gonglei@huawei.com>

Usage:
 -chardev socket,id=charcrypto0,path=/path/to/your/socket
 -object cryptodev-vhost-user,id=cryptodev0,chardev=charcrypto0
 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com>
---
 backends/Makefile.objs           |   6 +
 backends/cryptodev-vhost-user.c  | 331 +++++++++++++++++++++++++++++++++++++++
 backends/cryptodev-vhost.c       |  89 +++++++++++
 configure                        |  15 ++
 include/sysemu/cryptodev-vhost.h | 154 ++++++++++++++++++
 qemu-options.hx                  |  21 +++
 vl.c                             |   6 +
 7 files changed, 622 insertions(+)
 create mode 100644 backends/cryptodev-vhost-user.c
 create mode 100644 backends/cryptodev-vhost.c
 create mode 100644 include/sysemu/cryptodev-vhost.h

diff --git a/backends/Makefile.objs b/backends/Makefile.objs
index 67eeeba..9b7face 100644
--- a/backends/Makefile.objs
+++ b/backends/Makefile.objs
@@ -9,4 +9,10 @@ common-obj-$(CONFIG_LINUX) += hostmem-file.o
 common-obj-y += cryptodev.o
 common-obj-y += cryptodev-builtin.o
 
+ifeq ($(CONFIG_VIRTIO),y)
+common-obj-$(CONFIG_LINUX) += cryptodev-vhost.o
+common-obj-$(call land,$(CONFIG_VHOST_USER),$(CONFIG_LINUX)) += \
+    cryptodev-vhost-user.o
+endif
+
 common-obj-$(CONFIG_LINUX) += hostmem-memfd.o
diff --git a/backends/cryptodev-vhost-user.c b/backends/cryptodev-vhost-user.c
new file mode 100644
index 0000000..93c3f10
--- /dev/null
+++ b/backends/cryptodev-vhost-user.c
@@ -0,0 +1,331 @@
+/*
+ * QEMU Cryptodev backend for QEMU cipher APIs
+ *
+ * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
+ *
+ * Authors:
+ *    Gonglei <arei.gonglei@huawei.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "hw/boards.h"
+#include "qapi/error.h"
+#include "qapi/qmp/qerror.h"
+#include "qemu/error-report.h"
+#include "standard-headers/linux/virtio_crypto.h"
+#include "sysemu/cryptodev-vhost.h"
+#include "chardev/char-fe.h"
+
+
+/**
+ * @TYPE_CRYPTODEV_BACKEND_VHOST_USER:
+ * name of backend that uses vhost user server
+ */
+#define TYPE_CRYPTODEV_BACKEND_VHOST_USER "cryptodev-vhost-user"
+
+#define CRYPTODEV_BACKEND_VHOST_USER(obj) \
+    OBJECT_CHECK(CryptoDevBackendVhostUser, \
+                 (obj), TYPE_CRYPTODEV_BACKEND_VHOST_USER)
+
+
+typedef struct CryptoDevBackendVhostUser {
+    CryptoDevBackend parent_obj;
+
+    CharBackend chr;
+    char *chr_name;
+    bool opened;
+    CryptoDevBackendVhost *vhost_crypto[MAX_CRYPTO_QUEUE_NUM];
+} CryptoDevBackendVhostUser;
+
+static int
+cryptodev_vhost_user_running(
+             CryptoDevBackendVhost *crypto)
+{
+    return crypto ? 1 : 0;
+}
+
+static void cryptodev_vhost_user_stop(int queues,
+                          CryptoDevBackendVhostUser *s)
+{
+    size_t i;
+
+    for (i = 0; i < queues; i++) {
+        if (!cryptodev_vhost_user_running(s->vhost_crypto[i])) {
+            continue;
+        }
+
+        cryptodev_vhost_cleanup(s->vhost_crypto[i]);
+        s->vhost_crypto[i] = NULL;
+    }
+}
+
+static int
+cryptodev_vhost_user_start(int queues,
+                         CryptoDevBackendVhostUser *s)
+{
+    CryptoDevBackendVhostOptions options;
+    CryptoDevBackend *b = CRYPTODEV_BACKEND(s);
+    int max_queues;
+    size_t i;
+
+    for (i = 0; i < queues; i++) {
+        if (cryptodev_vhost_user_running(s->vhost_crypto[i])) {
+            continue;
+        }
+
+        options.opaque = &s->chr;
+        options.backend_type = VHOST_BACKEND_TYPE_USER;
+        options.cc = b->conf.peers.ccs[i];
+        s->vhost_crypto[i] = cryptodev_vhost_init(&options);
+        if (!s->vhost_crypto[i]) {
+            error_report("failed to init vhost_crypto for queue %zu", i);
+            goto err;
+        }
+
+        if (i == 0) {
+            max_queues =
+              cryptodev_vhost_get_max_queues(s->vhost_crypto[i]);
+            if (queues > max_queues) {
+                error_report("you are asking more queues than supported: %d",
+                             max_queues);
+                goto err;
+            }
+        }
+    }
+
+    return 0;
+
+err:
+    cryptodev_vhost_user_stop(i + 1, s);
+    return -1;
+}
+
+static Chardev *
+cryptodev_vhost_claim_chardev(CryptoDevBackendVhostUser *s,
+                                    Error **errp)
+{
+    Chardev *chr;
+
+    if (s->chr_name == NULL) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
+                   "chardev", "a valid character device");
+        return NULL;
+    }
+
+    chr = qemu_chr_find(s->chr_name);
+    if (chr == NULL) {
+        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
+                  "Device '%s' not found", s->chr_name);
+        return NULL;
+    }
+
+    return chr;
+}
+
+static void cryptodev_vhost_user_event(void *opaque, int event)
+{
+    CryptoDevBackendVhostUser *s = opaque;
+    CryptoDevBackend *b = CRYPTODEV_BACKEND(s);
+    Error *err = NULL;
+    int queues = b->conf.peers.queues;
+
+    assert(queues < MAX_CRYPTO_QUEUE_NUM);
+
+    switch (event) {
+    case CHR_EVENT_OPENED:
+        if (cryptodev_vhost_user_start(queues, s) < 0) {
+            exit(1);
+        }
+        b->ready = true;
+        break;
+    case CHR_EVENT_CLOSED:
+        b->ready = false;
+        cryptodev_vhost_user_stop(queues, s);
+        break;
+    }
+
+    if (err) {
+        error_report_err(err);
+    }
+}
+
+static void cryptodev_vhost_user_init(
+             CryptoDevBackend *backend, Error **errp)
+{
+    int queues = backend->conf.peers.queues;
+    size_t i;
+    Error *local_err = NULL;
+    Chardev *chr;
+    CryptoDevBackendClient *cc;
+    CryptoDevBackendVhostUser *s =
+                      CRYPTODEV_BACKEND_VHOST_USER(backend);
+
+    chr = cryptodev_vhost_claim_chardev(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    s->opened = true;
+
+    for (i = 0; i < queues; i++) {
+        cc = cryptodev_backend_new_client(
+                  "cryptodev-vhost-user", NULL);
+        cc->info_str = g_strdup_printf("cryptodev-vhost-user%zu to %s ",
+                                       i, chr->label);
+        cc->queue_index = i;
+
+        backend->conf.peers.ccs[i] = cc;
+
+        if (i == 0) {
+            if (!qemu_chr_fe_init(&s->chr, chr, &local_err)) {
+                error_propagate(errp, local_err);
+                return;
+            }
+        }
+    }
+
+    qemu_chr_fe_set_handlers(&s->chr, NULL, NULL,
+                     cryptodev_vhost_user_event, NULL, s, NULL, true);
+
+    backend->conf.crypto_services =
+                         1u << VIRTIO_CRYPTO_SERVICE_CIPHER |
+                         1u << VIRTIO_CRYPTO_SERVICE_HASH |
+                         1u << VIRTIO_CRYPTO_SERVICE_MAC;
+    backend->conf.cipher_algo_l = 1u << VIRTIO_CRYPTO_CIPHER_AES_CBC;
+    backend->conf.hash_algo = 1u << VIRTIO_CRYPTO_HASH_SHA1;
+}
+
+static int64_t cryptodev_vhost_user_sym_create_session(
+           CryptoDevBackend *backend,
+           CryptoDevBackendSymSessionInfo *sess_info,
+           uint32_t queue_index, Error **errp)
+{
+    return 0;
+}
+
+static int cryptodev_vhost_user_sym_close_session(
+           CryptoDevBackend *backend,
+           uint64_t session_id,
+           uint32_t queue_index, Error **errp)
+{
+    return 0;
+}
+
+static int cryptodev_vhost_user_sym_operation(
+                 CryptoDevBackend *backend,
+                 CryptoDevBackendSymOpInfo *op_info,
+                 uint32_t queue_index, Error **errp)
+{
+    return VIRTIO_CRYPTO_OK;
+}
+
+static void cryptodev_vhost_user_cleanup(
+             CryptoDevBackend *backend,
+             Error **errp)
+{
+    CryptoDevBackendVhostUser *s =
+                      CRYPTODEV_BACKEND_VHOST_USER(backend);
+    size_t i;
+    int queues = backend->conf.peers.queues;
+    CryptoDevBackendClient *cc;
+
+    cryptodev_vhost_user_stop(queues, s);
+
+    for (i = 0; i < queues; i++) {
+        cc = backend->conf.peers.ccs[i];
+        if (cc) {
+            cryptodev_backend_free_client(cc);
+            backend->conf.peers.ccs[i] = NULL;
+        }
+    }
+}
+
+static void cryptodev_vhost_user_set_chardev(Object *obj,
+                                    const char *value, Error **errp)
+{
+    CryptoDevBackendVhostUser *s =
+                      CRYPTODEV_BACKEND_VHOST_USER(obj);
+
+    if (s->opened) {
+        error_setg(errp, QERR_PERMISSION_DENIED);
+    } else {
+        g_free(s->chr_name);
+        s->chr_name = g_strdup(value);
+    }
+}
+
+static char *
+cryptodev_vhost_user_get_chardev(Object *obj, Error **errp)
+{
+    CryptoDevBackendVhostUser *s =
+                      CRYPTODEV_BACKEND_VHOST_USER(obj);
+    Chardev *chr = qemu_chr_fe_get_driver(&s->chr);
+
+    if (chr && chr->label) {
+        return g_strdup(chr->label);
+    }
+
+    return NULL;
+}
+
+static void cryptodev_vhost_user_instance_int(Object *obj)
+{
+    object_property_add_str(obj, "chardev",
+                            cryptodev_vhost_user_get_chardev,
+                            cryptodev_vhost_user_set_chardev,
+                            NULL);
+}
+
+static void cryptodev_vhost_user_finalize(Object *obj)
+{
+    CryptoDevBackendVhostUser *s =
+                      CRYPTODEV_BACKEND_VHOST_USER(obj);
+
+    qemu_chr_fe_deinit(&s->chr, false);
+
+    g_free(s->chr_name);
+}
+
+static void
+cryptodev_vhost_user_class_init(ObjectClass *oc, void *data)
+{
+    CryptoDevBackendClass *bc = CRYPTODEV_BACKEND_CLASS(oc);
+
+    bc->init = cryptodev_vhost_user_init;
+    bc->cleanup = cryptodev_vhost_user_cleanup;
+    bc->create_session = cryptodev_vhost_user_sym_create_session;
+    bc->close_session = cryptodev_vhost_user_sym_close_session;
+    bc->do_sym_op = cryptodev_vhost_user_sym_operation;
+}
+
+static const TypeInfo cryptodev_vhost_user_info = {
+    .name = TYPE_CRYPTODEV_BACKEND_VHOST_USER,
+    .parent = TYPE_CRYPTODEV_BACKEND,
+    .class_init = cryptodev_vhost_user_class_init,
+    .instance_init = cryptodev_vhost_user_instance_int,
+    .instance_finalize = cryptodev_vhost_user_finalize,
+    .instance_size = sizeof(CryptoDevBackendVhostUser),
+};
+
+static void
+cryptodev_vhost_user_register_types(void)
+{
+    type_register_static(&cryptodev_vhost_user_info);
+}
+
+type_init(cryptodev_vhost_user_register_types);
diff --git a/backends/cryptodev-vhost.c b/backends/cryptodev-vhost.c
new file mode 100644
index 0000000..27e1c4a
--- /dev/null
+++ b/backends/cryptodev-vhost.c
@@ -0,0 +1,89 @@
+/*
+ * QEMU Cryptodev backend for QEMU cipher APIs
+ *
+ * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
+ *
+ * Authors:
+ *    Gonglei <arei.gonglei@huawei.com>
+ *    Jay Zhou <jianjay.zhou@huawei.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "sysemu/cryptodev-vhost.h"
+
+#ifdef CONFIG_VHOST_CRYPTO
+uint64_t
+cryptodev_vhost_get_max_queues(
+                        CryptoDevBackendVhost *crypto)
+{
+    return crypto->dev.max_queues;
+}
+
+void cryptodev_vhost_cleanup(CryptoDevBackendVhost *crypto)
+{
+    vhost_dev_cleanup(&crypto->dev);
+    g_free(crypto);
+}
+
+struct CryptoDevBackendVhost *
+cryptodev_vhost_init(
+             CryptoDevBackendVhostOptions *options)
+{
+    int r;
+    CryptoDevBackendVhost *crypto;
+
+    crypto = g_new(CryptoDevBackendVhost, 1);
+    crypto->dev.max_queues = 1;
+    crypto->dev.nvqs = 1;
+    crypto->dev.vqs = crypto->vqs;
+
+    crypto->cc = options->cc;
+
+    crypto->dev.protocol_features = 0;
+    crypto->backend = -1;
+
+    /* vhost-user needs vq_index to initiate a specific queue pair */
+    crypto->dev.vq_index = crypto->cc->queue_index * crypto->dev.nvqs;
+
+    r = vhost_dev_init(&crypto->dev, options->opaque, options->backend_type, 0);
+    if (r < 0) {
+        goto fail;
+    }
+
+    return crypto;
+fail:
+    g_free(crypto);
+    return NULL;
+}
+
+#else
+uint64_t
+cryptodev_vhost_get_max_queues(CryptoDevBackendVhost *crypto)
+{
+    return 0;
+}
+
+void cryptodev_vhost_cleanup(CryptoDevBackendVhost *crypto)
+{
+}
+
+struct CryptoDevBackendVhost *
+cryptodev_vhost_init(CryptoDevBackendVhostOptions *options)
+{
+    return NULL;
+}
+#endif
diff --git a/configure b/configure
index 39f3a43..e55d67d 100755
--- a/configure
+++ b/configure
@@ -344,6 +344,7 @@ xfs=""
 tcg="yes"
 
 vhost_net="no"
+vhost_crypto="no"
 vhost_scsi="no"
 vhost_vsock="no"
 vhost_user=""
@@ -813,6 +814,7 @@ Linux)
   linux_user="yes"
   kvm="yes"
   vhost_net="yes"
+  vhost_crypto="yes"
   vhost_scsi="yes"
   vhost_vsock="yes"
   QEMU_INCLUDES="-I\$(SRC_PATH)/linux-headers -I$(pwd)/linux-headers $QEMU_INCLUDES"
@@ -1183,6 +1185,14 @@ for opt do
   ;;
   --enable-vhost-net) vhost_net="yes"
   ;;
+  --disable-vhost-crypto) vhost_crypto="no"
+  ;;
+  --enable-vhost-crypto)
+      vhost_crypto="yes"
+      if test "$mingw32" = "yes"; then
+          error_exit "vhost-crypto isn't available on win32"
+      fi
+  ;;
   --disable-vhost-scsi) vhost_scsi="no"
   ;;
   --enable-vhost-scsi) vhost_scsi="yes"
@@ -1580,6 +1590,7 @@ disabled with --disable-FEATURE, default is enabled if available:
   cap-ng          libcap-ng support
   attr            attr and xattr support
   vhost-net       vhost-net acceleration support
+  vhost-crypto    vhost-crypto acceleration support
   spice           spice
   rbd             rados block device (rbd)
   libiscsi        iscsi support
@@ -5771,6 +5782,7 @@ echo "posix_madvise     $posix_madvise"
 echo "posix_memalign    $posix_memalign"
 echo "libcap-ng support $cap_ng"
 echo "vhost-net support $vhost_net"
+echo "vhost-crypto support $vhost_crypto"
 echo "vhost-scsi support $vhost_scsi"
 echo "vhost-vsock support $vhost_vsock"
 echo "vhost-user support $vhost_user"
@@ -6855,6 +6867,9 @@ if supported_kvm_target $target; then
             echo "CONFIG_VHOST_USER_NET_TEST_$target_name=y" >> $config_host_mak
         fi
     fi
+    if test "$vhost_crypto" = "yes" ; then
+        echo "CONFIG_VHOST_CRYPTO=y" >> $config_target_mak
+    fi
 fi
 if supported_hax_target $target; then
     echo "CONFIG_HAX=y" >> $config_target_mak
diff --git a/include/sysemu/cryptodev-vhost.h b/include/sysemu/cryptodev-vhost.h
new file mode 100644
index 0000000..fb26b86
--- /dev/null
+++ b/include/sysemu/cryptodev-vhost.h
@@ -0,0 +1,154 @@
+/*
+ * QEMU Crypto Device Common Vhost Implement
+ *
+ * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
+ *
+ * Authors:
+ *    Gonglei <arei.gonglei@huawei.com>
+ *    Jay Zhou <jianjay.zhou@huawei.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#ifndef CRYPTODEV_VHOST_H
+#define CRYPTODEV_VHOST_H
+
+#include "qemu-common.h"
+#include "hw/virtio/vhost.h"
+#include "hw/virtio/vhost-backend.h"
+#include "chardev/char.h"
+
+#include "sysemu/cryptodev.h"
+
+
+typedef struct CryptoDevBackendVhostOptions {
+    VhostBackendType backend_type;
+    void *opaque;
+    int total_queues;
+    CryptoDevBackendClient *cc;
+} CryptoDevBackendVhostOptions;
+
+typedef struct CryptoDevBackendVhost {
+    struct vhost_dev dev;
+    struct vhost_virtqueue vqs[1];
+    int backend;
+    CryptoDevBackendClient *cc;
+} CryptoDevBackendVhost;
+
+/**
+ * cryptodev_vhost_get_max_queues:
+ * @crypto: the cryptodev backend common vhost object
+ *
+ * Get the maximum queue number of @crypto.
+ *
+ *
+ * Returns: the maximum queue number
+ */
+uint64_t
+cryptodev_vhost_get_max_queues(
+                        CryptoDevBackendVhost *crypto);
+
+
+/**
+ * cryptodev_vhost_init:
+ * @options: the common vhost object's option
+ *
+ * Creates a new cryptodev backend common vhost object
+ *
+ ** The returned object must be released with
+ * cryptodev_vhost_cleanup() when no
+ * longer required
+ *
+ * Returns: the cryptodev backend common vhost object
+ */
+struct CryptoDevBackendVhost *
+cryptodev_vhost_init(
+             CryptoDevBackendVhostOptions *options);
+
+/**
+ * cryptodev_vhost_cleanup:
+ * @crypto: the cryptodev backend common vhost object
+ *
+ * Clean the resouce associated with @crypto that realizaed
+ * by cryptodev_vhost_init()
+ *
+ */
+void cryptodev_vhost_cleanup(
+                        CryptoDevBackendVhost *crypto);
+
+/**
+ * cryptodev_get_vhost:
+ * @cc: the client object for each queue
+ * @b: the cryptodev backend common vhost object
+ * @queue: the cryptodev backend queue index
+ *
+ * Gets a new cryptodev backend common vhost object based on
+ * @b and @queue
+ *
+ * Returns: the cryptodev backend common vhost object
+ */
+CryptoDevBackendVhost *
+cryptodev_get_vhost(CryptoDevBackendClient *cc,
+                            CryptoDevBackend *b,
+                            uint16_t queue);
+/**
+ * cryptodev_vhost_start:
+ * @dev: the virtio crypto object
+ * @total_queues: the total count of queue
+ *
+ * Starts the vhost crypto logic
+ *
+ * Returns: 0 for success, negative for errors
+ */
+int cryptodev_vhost_start(VirtIODevice *dev, int total_queues);
+
+/**
+ * cryptodev_vhost_stop:
+ * @dev: the virtio crypto object
+ * @total_queues: the total count of queue
+ *
+ * Stops the vhost crypto logic
+ *
+ */
+void cryptodev_vhost_stop(VirtIODevice *dev, int total_queues);
+
+/**
+ * cryptodev_vhost_virtqueue_mask:
+ * @dev: the virtio crypto object
+ * @queue: the cryptodev backend queue index
+ * @idx: the virtqueue index
+ * @mask: mask or not (true or false)
+ *
+ * Mask/unmask events for @idx virtqueue on @dev device
+ *
+ */
+void cryptodev_vhost_virtqueue_mask(VirtIODevice *dev,
+                                           int queue,
+                                           int idx, bool mask);
+
+/**
+ * cryptodev_vhost_virtqueue_pending:
+ * @dev: the virtio crypto object
+ * @queue: the cryptodev backend queue index
+ * @idx: the virtqueue index
+ *
+ * Test and clear event pending status for @idx virtqueue on @dev device.
+ * Should be called after unmask to avoid losing events.
+ *
+ * Returns: true for success, false for errors
+ */
+bool cryptodev_vhost_virtqueue_pending(VirtIODevice *dev,
+                                              int queue, int idx);
+
+#endif /* CRYPTODEV_VHOST_H */
diff --git a/qemu-options.hx b/qemu-options.hx
index 8ccd5dc..fea949d 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4233,6 +4233,27 @@ which specify the queue number of cryptodev backend, the default of
    [...]
 @end example
 
+@item -object cryptodev-vhost-user,id=@var{id},chardev=@var{chardevid}[,queues=@var{queues}]
+
+Creates a vhost-user cryptodev backend, backed by a chardev @var{chardevid}.
+The @var{id} parameter is a unique ID that will be used to reference this
+cryptodev backend from the @option{virtio-crypto} device.
+The chardev should be a unix domain socket backed one. The vhost-user uses
+a specifically defined protocol to pass vhost ioctl replacement messages
+to an application on the other end of the socket.
+The @var{queues} parameter is optional, which specify the queue number
+of cryptodev backend for multiqueue vhost-user, the default of @var{queues} is 1.
+
+@example
+
+ # qemu-system-x86_64 \
+   [...] \
+       -chardev socket,id=chardev0,path=/path/to/socket \
+       -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \
+       -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
+   [...]
+@end example
+
 @item -object secret,id=@var{id},data=@var{string},format=@var{raw|base64}[,keyid=@var{secretid},iv=@var{string}]
 @item -object secret,id=@var{id},file=@var{filename},format=@var{raw|base64}[,keyid=@var{secretid},iv=@var{string}]
 
diff --git a/vl.c b/vl.c
index 9e7235d..6d15386 100644
--- a/vl.c
+++ b/vl.c
@@ -2838,6 +2838,12 @@ static bool object_create_initial(const char *type)
         return false;
     }
 
+#if defined(CONFIG_VHOST_USER) && defined(CONFIG_LINUX)
+    if (g_str_equal(type, "cryptodev-vhost-user")) {
+        return false;
+    }
+#endif
+
     /*
      * return false for concrete netfilters since
      * they depend on netdevs already existing
-- 
1.8.3.1