Re: [Qemu-devel] [PULL 15/26] cryptodev: add vhost-user as a new cryptodev backend

[Michael S. Tsirkin]

On Thu, Feb 08, 2018 at 09:09:13PM +0200, Michael S. Tsirkin wrote:
> From: Gonglei <address@hidden>
> 
> 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 <address@hidden>
> Signed-off-by: Longpeng(Mike) <address@hidden>
> Signed-off-by: Jay Zhou <address@hidden>
> Reviewed-by: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Michael S. Tsirkin <address@hidden>

Dropped this and follow-up patches due to failures
on non-linux hosts and stop corrections.

> ---
>  configure                        |  15 ++
>  include/sysemu/cryptodev-vhost.h | 154 ++++++++++++++++++
>  backends/cryptodev-vhost-user.c  | 333 
> +++++++++++++++++++++++++++++++++++++++
>  backends/cryptodev-vhost.c       |  89 +++++++++++
>  vl.c                             |   6 +
>  backends/Makefile.objs           |   6 +
>  qemu-options.hx                  |  21 +++
>  7 files changed, 624 insertions(+)
>  create mode 100644 include/sysemu/cryptodev-vhost.h
>  create mode 100644 backends/cryptodev-vhost-user.c
>  create mode 100644 backends/cryptodev-vhost.c
> 
> diff --git a/configure b/configure
> index 831ebf2..296f980 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=""
> @@ -814,6 +815,7 @@ 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 
> $QEMU_INCLUDES"
> @@ -1184,6 +1186,14 @@ for opt do
>    ;;
>    --enable-vhost-net) vhost_net="yes"
>    ;;
> +  --disable-vhost-crypto) vhost_crypto="no"
> +  ;;
> +  --enable-vhost-crypto)
> +      vhost_crypto="yes"
> +      if test "$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"
> @@ -1582,6 +1592,7 @@ 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
> @@ -5704,6 +5715,7 @@ echo "madvise           $madvise"
>  echo "posix_madvise     $posix_madvise"
>  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"
> @@ -6783,6 +6795,9 @@ 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 <address@hidden>
> + *    Jay Zhou <address@hidden>
> + *
> + * 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/backends/cryptodev-vhost-user.c b/backends/cryptodev-vhost-user.c
> new file mode 100644
> index 0000000..4e63ece
> --- /dev/null
> +++ b/backends/cryptodev-vhost-user.c
> @@ -0,0 +1,333 @@
> +/*
> + * QEMU Cryptodev backend for QEMU cipher APIs
> + *
> + * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
> + *
> + * Authors:
> + *    Gonglei <address@hidden>
> + *
> + * 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;
> +        }
> +
> +        if (s->vhost_crypto) {
> +            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 %lu", 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%lu 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 <address@hidden>
> + *    Jay Zhou <address@hidden>
> + *
> + * 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/vl.c b/vl.c
> index 32db91d..4ef4e67 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2852,6 +2852,12 @@ 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
> diff --git a/backends/Makefile.objs b/backends/Makefile.objs
> index 67eeeba..efdcc5a 100644
> --- a/backends/Makefile.objs
> +++ b/backends/Makefile.objs
> @@ -10,3 +10,9 @@ common-obj-y += cryptodev.o
>  common-obj-y += cryptodev-builtin.o
>  
>  common-obj-$(CONFIG_LINUX) += hostmem-memfd.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
> diff --git a/qemu-options.hx b/qemu-options.hx
> index d15c171..cdc464c 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -4225,6 +4225,27 @@ which specify the queue number of cryptodev backend, 
> the default of
>     [...]
>  @end example
>  
> address@hidden -object 
> cryptodev-vhost-user,address@hidden,address@hidden,address@hidden
> +
> +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.
> +
> address@hidden
> +
> + # 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 \
> +   [...]
> address@hidden example
> +
>  @item -object 
> secret,address@hidden,address@hidden,address@hidden|base64}[,address@hidden,address@hidden
>  @item -object 
> secret,address@hidden,address@hidden,address@hidden|base64}[,address@hidden,address@hidden
>  
> -- 
> MST
>