block/vxhs.c: Add support for a new block device type called "vxhs"

Source code for the qnio library that this code loads can be downloaded from:
https://github.com/VeritasHyperScale/libqnio.git

Sample command line using JSON syntax:
./x86_64-softmmu/qemu-system-x86_64 -name instance-00000008 -S -vnc 0.0.0.0:0
-k en-us -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
-msg timestamp=on
'json:{"driver":"vxhs","vdisk-id":"c3e9095a-a5ee-4dce-afeb-2a59fb387410",
"server":{"host":"172.172.17.4","port":"9999"}}'

Sample command line using URI syntax:
qemu-img convert -f raw -O raw -n
/var/lib/nova/instances/_base/0c5eacd5ebea5ed914b6a3e7b18f1ce734c386ad
vxhs://192.168.0.1:9999/c6718f6b-0401-441d-a8c3-1f0064d75ee0

Sample command line using TLS credentials (run in secure mode):
./qemu-io --object
tls-creds-x509,id=tls0,dir=/etc/pki/qemu/vxhs,endpoint=client -c 'read
-v 66000 2.5k' 'json:{"server.host": "127.0.0.1", "server.port": "9999",
"vdisk-id": "/test.raw", "driver": "vxhs", "tls-creds":"tls0"}'

[Jeff: Modified trace-events with the correct string formatting]

Signed-off-by: Ashish Mittal <Ashish.Mittal@veritas.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Message-id: 1491277689-24949-2-git-send-email-Ashish.Mittal@veritas.com

3 files changed, 594 insertions, 0 deletions

diff --git a/block/Makefile.objs b/block/Makefile.objs
index de96f8ee80..ea955302c8 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -19,6 +19,7 @@ block-obj-$(CONFIG_LIBNFS) += nfs.o
 block-obj-$(CONFIG_CURL) += curl.o
 block-obj-$(CONFIG_RBD) += rbd.o
 block-obj-$(CONFIG_GLUSTERFS) += gluster.o
+block-obj-$(CONFIG_VXHS) += vxhs.o
 block-obj-$(CONFIG_LIBSSH2) += ssh.o
 block-obj-y += accounting.o dirty-bitmap.o
 block-obj-y += write-threshold.o
@@ -38,6 +39,7 @@ rbd.o-cflags       := $(RBD_CFLAGS)
 rbd.o-libs         := $(RBD_LIBS)
 gluster.o-cflags   := $(GLUSTERFS_CFLAGS)
 gluster.o-libs     := $(GLUSTERFS_LIBS)
+vxhs.o-libs        := $(VXHS_LIBS)
 ssh.o-cflags       := $(LIBSSH2_CFLAGS)
 ssh.o-libs         := $(LIBSSH2_LIBS)
 block-obj-$(if $(CONFIG_BZIP2),m,n) += dmg-bz2.o
diff --git a/block/trace-events b/block/trace-events
index 0bc5c0adf1..9a71c7fb04 100644
--- a/block/trace-events
+++ b/block/trace-events
@@ -110,3 +110,20 @@ qed_aio_write_data(void *s, void *acb, int ret, uint64_t offset, size_t len) "s
 qed_aio_write_prefill(void *s, void *acb, uint64_t start, size_t len, uint64_t offset) "s %p acb %p start %"PRIu64" len %zu offset %"PRIu64
 qed_aio_write_postfill(void *s, void *acb, uint64_t start, size_t len, uint64_t offset) "s %p acb %p start %"PRIu64" len %zu offset %"PRIu64
 qed_aio_write_main(void *s, void *acb, int ret, uint64_t offset, size_t len) "s %p acb %p ret %d offset %"PRIu64" len %zu"
+
+# block/vxhs.c
+vxhs_iio_callback(int error) "ctx is NULL: error %d"
+vxhs_iio_callback_chnfail(int err, int error) "QNIO channel failed, no i/o %d, %d"
+vxhs_iio_callback_unknwn(int opcode, int err) "unexpected opcode %d, errno %d"
+vxhs_aio_rw_invalid(int req) "Invalid I/O request iodir %d"
+vxhs_aio_rw_ioerr(char *guid, int iodir, uint64_t size, uint64_t off, void *acb, int ret, int err) "IO ERROR (vDisk %s) FOR : Read/Write = %d size = %"PRIu64" offset = %"PRIu64" ACB = %p. Error = %d, errno = %d"
+vxhs_get_vdisk_stat_err(char *guid, int ret, int err) "vDisk (%s) stat ioctl failed, ret = %d, errno = %d"
+vxhs_get_vdisk_stat(char *vdisk_guid, uint64_t vdisk_size) "vDisk %s stat ioctl returned size %"PRIu64
+vxhs_complete_aio(void *acb, uint64_t ret) "aio failed acb %p ret %"PRIu64
+vxhs_parse_uri_filename(const char *filename) "URI passed via bdrv_parse_filename %s"
+vxhs_open_vdiskid(const char *vdisk_id) "Opening vdisk-id %s"
+vxhs_open_hostinfo(char *of_vsa_addr, int port) "Adding host %s:%d to BDRVVXHSState"
+vxhs_open_iio_open(const char *host) "Failed to connect to storage agent on host %s"
+vxhs_parse_uri_hostinfo(char *host, int port) "Host: IP %s, Port %d"
+vxhs_close(char *vdisk_guid) "Closing vdisk %s"
+vxhs_get_creds(const char *cacert, const char *client_key, const char *client_cert) "cacert %s, client_key %s, client_cert %s"
diff --git a/block/vxhs.c b/block/vxhs.c
new file mode 100644
index 0000000000..9ffe9d3814
--- /dev/null
+++ b/block/vxhs.c
@@ -0,0 +1,575 @@
+/*
+ * QEMU Block driver for Veritas HyperScale (VxHS)
+ *
+ * Copyright (c) 2017 Veritas Technologies LLC.
+ *
+ * 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 <qnio/qnio_api.h>
+#include <sys/param.h>
+#include "block/block_int.h"
+#include "qapi/qmp/qerror.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qstring.h"
+#include "trace.h"
+#include "qemu/uri.h"
+#include "qapi/error.h"
+#include "qemu/uuid.h"
+#include "crypto/tlscredsx509.h"
+
+#define VXHS_OPT_FILENAME           "filename"
+#define VXHS_OPT_VDISK_ID           "vdisk-id"
+#define VXHS_OPT_SERVER             "server"
+#define VXHS_OPT_HOST               "host"
+#define VXHS_OPT_PORT               "port"
+
+/* Only accessed under QEMU global mutex */
+static uint32_t vxhs_ref;
+
+typedef enum {
+    VDISK_AIO_READ,
+    VDISK_AIO_WRITE,
+} VDISKAIOCmd;
+
+/*
+ * HyperScale AIO callbacks structure
+ */
+typedef struct VXHSAIOCB {
+    BlockAIOCB common;
+    int err;
+} VXHSAIOCB;
+
+typedef struct VXHSvDiskHostsInfo {
+    void *dev_handle; /* Device handle */
+    char *host; /* Host name or IP */
+    int port; /* Host's port number */
+} VXHSvDiskHostsInfo;
+
+/*
+ * Structure per vDisk maintained for state
+ */
+typedef struct BDRVVXHSState {
+    VXHSvDiskHostsInfo vdisk_hostinfo; /* Per host info */
+    char *vdisk_guid;
+    char *tlscredsid; /* tlscredsid */
+} BDRVVXHSState;
+
+static void vxhs_complete_aio_bh(void *opaque)
+{
+    VXHSAIOCB *acb = opaque;
+    BlockCompletionFunc *cb = acb->common.cb;
+    void *cb_opaque = acb->common.opaque;
+    int ret = 0;
+
+    if (acb->err != 0) {
+        trace_vxhs_complete_aio(acb, acb->err);
+        ret = (-EIO);
+    }
+
+    qemu_aio_unref(acb);
+    cb(cb_opaque, ret);
+}
+
+/*
+ * Called from a libqnio thread
+ */
+static void vxhs_iio_callback(void *ctx, uint32_t opcode, uint32_t error)
+{
+    VXHSAIOCB *acb = NULL;
+
+    switch (opcode) {
+    case IRP_READ_REQUEST:
+    case IRP_WRITE_REQUEST:
+
+        /*
+         * ctx is VXHSAIOCB*
+         * ctx is NULL if error is QNIOERROR_CHANNEL_HUP
+         */
+        if (ctx) {
+            acb = ctx;
+        } else {
+            trace_vxhs_iio_callback(error);
+            goto out;
+        }
+
+        if (error) {
+            if (!acb->err) {
+                acb->err = error;
+            }
+            trace_vxhs_iio_callback(error);
+        }
+
+        aio_bh_schedule_oneshot(bdrv_get_aio_context(acb->common.bs),
+                                vxhs_complete_aio_bh, acb);
+        break;
+
+    default:
+        if (error == QNIOERROR_HUP) {
+            /*
+             * Channel failed, spontaneous notification,
+             * not in response to I/O
+             */
+            trace_vxhs_iio_callback_chnfail(error, errno);
+        } else {
+            trace_vxhs_iio_callback_unknwn(opcode, error);
+        }
+        break;
+    }
+out:
+    return;
+}
+
+static QemuOptsList runtime_opts = {
+    .name = "vxhs",
+    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
+    .desc = {
+        {
+            .name = VXHS_OPT_FILENAME,
+            .type = QEMU_OPT_STRING,
+            .help = "URI to the Veritas HyperScale image",
+        },
+        {
+            .name = VXHS_OPT_VDISK_ID,
+            .type = QEMU_OPT_STRING,
+            .help = "UUID of the VxHS vdisk",
+        },
+        {
+            .name = "tls-creds",
+            .type = QEMU_OPT_STRING,
+            .help = "ID of the TLS/SSL credentials to use",
+        },
+        { /* end of list */ }
+    },
+};
+
+static QemuOptsList runtime_tcp_opts = {
+    .name = "vxhs_tcp",
+    .head = QTAILQ_HEAD_INITIALIZER(runtime_tcp_opts.head),
+    .desc = {
+        {
+            .name = VXHS_OPT_HOST,
+            .type = QEMU_OPT_STRING,
+            .help = "host address (ipv4 addresses)",
+        },
+        {
+            .name = VXHS_OPT_PORT,
+            .type = QEMU_OPT_NUMBER,
+            .help = "port number on which VxHSD is listening (default 9999)",
+            .def_value_str = "9999"
+        },
+        { /* end of list */ }
+    },
+};
+
+/*
+ * Parse incoming URI and populate *options with the host
+ * and device information
+ */
+static int vxhs_parse_uri(const char *filename, QDict *options)
+{
+    URI *uri = NULL;
+    char *port;
+    int ret = 0;
+
+    trace_vxhs_parse_uri_filename(filename);
+    uri = uri_parse(filename);
+    if (!uri || !uri->server || !uri->path) {
+        uri_free(uri);
+        return -EINVAL;
+    }
+
+    qdict_put(options, VXHS_OPT_SERVER".host", qstring_from_str(uri->server));
+
+    if (uri->port) {
+        port = g_strdup_printf("%d", uri->port);
+        qdict_put(options, VXHS_OPT_SERVER".port", qstring_from_str(port));
+        g_free(port);
+    }
+
+    qdict_put(options, "vdisk-id", qstring_from_str(uri->path));
+
+    trace_vxhs_parse_uri_hostinfo(uri->server, uri->port);
+    uri_free(uri);
+
+    return ret;
+}
+
+static void vxhs_parse_filename(const char *filename, QDict *options,
+                                Error **errp)
+{
+    if (qdict_haskey(options, "vdisk-id") || qdict_haskey(options, "server")) {
+        error_setg(errp, "vdisk-id/server and a file name may not be specified "
+                         "at the same time");
+        return;
+    }
+
+    if (strstr(filename, "://")) {
+        int ret = vxhs_parse_uri(filename, options);
+        if (ret < 0) {
+            error_setg(errp, "Invalid URI. URI should be of the form "
+                       "  vxhs://<host_ip>:<port>/<vdisk-id>");
+        }
+    }
+}
+
+static int vxhs_init_and_ref(void)
+{
+    if (vxhs_ref++ == 0) {
+        if (iio_init(QNIO_VERSION, vxhs_iio_callback)) {
+            return -ENODEV;
+        }
+    }
+    return 0;
+}
+
+static void vxhs_unref(void)
+{
+    if (--vxhs_ref == 0) {
+        iio_fini();
+    }
+}
+
+static void vxhs_get_tls_creds(const char *id, char **cacert,
+                               char **key, char **cert, Error **errp)
+{
+    Object *obj;
+    QCryptoTLSCreds *creds;
+    QCryptoTLSCredsX509 *creds_x509;
+
+    obj = object_resolve_path_component(
+        object_get_objects_root(), id);
+
+    if (!obj) {
+        error_setg(errp, "No TLS credentials with id '%s'",
+                   id);
+        return;
+    }
+
+    creds_x509 = (QCryptoTLSCredsX509 *)
+        object_dynamic_cast(obj, TYPE_QCRYPTO_TLS_CREDS_X509);
+
+    if (!creds_x509) {
+        error_setg(errp, "Object with id '%s' is not TLS credentials",
+                   id);
+        return;
+    }
+
+    creds = &creds_x509->parent_obj;
+
+    if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT) {
+        error_setg(errp,
+                   "Expecting TLS credentials with a client endpoint");
+        return;
+    }
+
+    /*
+     * Get the cacert, client_cert and client_key file names.
+     */
+    if (!creds->dir) {
+        error_setg(errp, "TLS object missing 'dir' property value");
+        return;
+    }
+
+    *cacert = g_strdup_printf("%s/%s", creds->dir,
+                              QCRYPTO_TLS_CREDS_X509_CA_CERT);
+    *cert = g_strdup_printf("%s/%s", creds->dir,
+                            QCRYPTO_TLS_CREDS_X509_CLIENT_CERT);
+    *key = g_strdup_printf("%s/%s", creds->dir,
+                           QCRYPTO_TLS_CREDS_X509_CLIENT_KEY);
+}
+
+static int vxhs_open(BlockDriverState *bs, QDict *options,
+                     int bdrv_flags, Error **errp)
+{
+    BDRVVXHSState *s = bs->opaque;
+    void *dev_handlep;
+    QDict *backing_options = NULL;
+    QemuOpts *opts = NULL;
+    QemuOpts *tcp_opts = NULL;
+    char *of_vsa_addr = NULL;
+    Error *local_err = NULL;
+    const char *vdisk_id_opt;
+    const char *server_host_opt;
+    int ret = 0;
+    char *cacert = NULL;
+    char *client_key = NULL;
+    char *client_cert = NULL;
+
+    ret = vxhs_init_and_ref();
+    if (ret < 0) {
+        ret = -EINVAL;
+        goto out;
+    }
+
+    /* Create opts info from runtime_opts and runtime_tcp_opts list */
+    opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
+    tcp_opts = qemu_opts_create(&runtime_tcp_opts, NULL, 0, &error_abort);
+
+    qemu_opts_absorb_qdict(opts, options, &local_err);
+    if (local_err) {
+        ret = -EINVAL;
+        goto out;
+    }
+
+    /* vdisk-id is the disk UUID */
+    vdisk_id_opt = qemu_opt_get(opts, VXHS_OPT_VDISK_ID);
+    if (!vdisk_id_opt) {
+        error_setg(&local_err, QERR_MISSING_PARAMETER, VXHS_OPT_VDISK_ID);
+        ret = -EINVAL;
+        goto out;
+    }
+
+    /* vdisk-id may contain a leading '/' */
+    if (strlen(vdisk_id_opt) > UUID_FMT_LEN + 1) {
+        error_setg(&local_err, "vdisk-id cannot be more than %d characters",
+                   UUID_FMT_LEN);
+        ret = -EINVAL;
+        goto out;
+    }
+
+    s->vdisk_guid = g_strdup(vdisk_id_opt);
+    trace_vxhs_open_vdiskid(vdisk_id_opt);
+
+    /* get the 'server.' arguments */
+    qdict_extract_subqdict(options, &backing_options, VXHS_OPT_SERVER".");
+
+    qemu_opts_absorb_qdict(tcp_opts, backing_options, &local_err);
+    if (local_err != NULL) {
+        ret = -EINVAL;
+        goto out;
+    }
+
+    server_host_opt = qemu_opt_get(tcp_opts, VXHS_OPT_HOST);
+    if (!server_host_opt) {
+        error_setg(&local_err, QERR_MISSING_PARAMETER,
+                   VXHS_OPT_SERVER"."VXHS_OPT_HOST);
+        ret = -EINVAL;
+        goto out;
+    }
+
+    if (strlen(server_host_opt) > MAXHOSTNAMELEN) {
+        error_setg(&local_err, "server.host cannot be more than %d characters",
+                   MAXHOSTNAMELEN);
+        ret = -EINVAL;
+        goto out;
+    }
+
+    /* check if we got tls-creds via the --object argument */
+    s->tlscredsid = g_strdup(qemu_opt_get(opts, "tls-creds"));
+    if (s->tlscredsid) {
+        vxhs_get_tls_creds(s->tlscredsid, &cacert, &client_key,
+                           &client_cert, &local_err);
+        if (local_err != NULL) {
+            ret = -EINVAL;
+            goto out;
+        }
+        trace_vxhs_get_creds(cacert, client_key, client_cert);
+    }
+
+    s->vdisk_hostinfo.host = g_strdup(server_host_opt);
+    s->vdisk_hostinfo.port = g_ascii_strtoll(qemu_opt_get(tcp_opts,
+                                                          VXHS_OPT_PORT),
+                                                          NULL, 0);
+
+    trace_vxhs_open_hostinfo(s->vdisk_hostinfo.host,
+                             s->vdisk_hostinfo.port);
+
+    of_vsa_addr = g_strdup_printf("of://%s:%d",
+                                  s->vdisk_hostinfo.host,
+                                  s->vdisk_hostinfo.port);
+
+    /*
+     * Open qnio channel to storage agent if not opened before
+     */
+    dev_handlep = iio_open(of_vsa_addr, s->vdisk_guid, 0,
+                           cacert, client_key, client_cert);
+    if (dev_handlep == NULL) {
+        trace_vxhs_open_iio_open(of_vsa_addr);
+        ret = -ENODEV;
+        goto out;
+    }
+    s->vdisk_hostinfo.dev_handle = dev_handlep;
+
+out:
+    g_free(of_vsa_addr);
+    QDECREF(backing_options);
+    qemu_opts_del(tcp_opts);
+    qemu_opts_del(opts);
+    g_free(cacert);
+    g_free(client_key);
+    g_free(client_cert);
+
+    if (ret < 0) {
+        vxhs_unref();
+        error_propagate(errp, local_err);
+        g_free(s->vdisk_hostinfo.host);
+        g_free(s->vdisk_guid);
+        g_free(s->tlscredsid);
+        s->vdisk_guid = NULL;
+    }
+
+    return ret;
+}
+
+static const AIOCBInfo vxhs_aiocb_info = {
+    .aiocb_size = sizeof(VXHSAIOCB)
+};
+
+/*
+ * This allocates QEMU-VXHS callback for each IO
+ * and is passed to QNIO. When QNIO completes the work,
+ * it will be passed back through the callback.
+ */
+static BlockAIOCB *vxhs_aio_rw(BlockDriverState *bs, int64_t sector_num,
+                               QEMUIOVector *qiov, int nb_sectors,
+                               BlockCompletionFunc *cb, void *opaque,
+                               VDISKAIOCmd iodir)
+{
+    VXHSAIOCB *acb = NULL;
+    BDRVVXHSState *s = bs->opaque;
+    size_t size;
+    uint64_t offset;
+    int iio_flags = 0;
+    int ret = 0;
+    void *dev_handle = s->vdisk_hostinfo.dev_handle;
+
+    offset = sector_num * BDRV_SECTOR_SIZE;
+    size = nb_sectors * BDRV_SECTOR_SIZE;
+    acb = qemu_aio_get(&vxhs_aiocb_info, bs, cb, opaque);
+
+    /*
+     * Initialize VXHSAIOCB.
+     */
+    acb->err = 0;
+
+    iio_flags = IIO_FLAG_ASYNC;
+
+    switch (iodir) {
+    case VDISK_AIO_WRITE:
+            ret = iio_writev(dev_handle, acb, qiov->iov, qiov->niov,
+                             offset, (uint64_t)size, iio_flags);
+            break;
+    case VDISK_AIO_READ:
+            ret = iio_readv(dev_handle, acb, qiov->iov, qiov->niov,
+                            offset, (uint64_t)size, iio_flags);
+            break;
+    default:
+            trace_vxhs_aio_rw_invalid(iodir);
+            goto errout;
+    }
+
+    if (ret != 0) {
+        trace_vxhs_aio_rw_ioerr(s->vdisk_guid, iodir, size, offset,
+                                acb, ret, errno);
+        goto errout;
+    }
+    return &acb->common;
+
+errout:
+    qemu_aio_unref(acb);
+    return NULL;
+}
+
+static BlockAIOCB *vxhs_aio_readv(BlockDriverState *bs,
+                                   int64_t sector_num, QEMUIOVector *qiov,
+                                   int nb_sectors,
+                                   BlockCompletionFunc *cb, void *opaque)
+{
+    return vxhs_aio_rw(bs, sector_num, qiov, nb_sectors, cb,
+                       opaque, VDISK_AIO_READ);
+}
+
+static BlockAIOCB *vxhs_aio_writev(BlockDriverState *bs,
+                                   int64_t sector_num, QEMUIOVector *qiov,
+                                   int nb_sectors,
+                                   BlockCompletionFunc *cb, void *opaque)
+{
+    return vxhs_aio_rw(bs, sector_num, qiov, nb_sectors,
+                       cb, opaque, VDISK_AIO_WRITE);
+}
+
+static void vxhs_close(BlockDriverState *bs)
+{
+    BDRVVXHSState *s = bs->opaque;
+
+    trace_vxhs_close(s->vdisk_guid);
+
+    g_free(s->vdisk_guid);
+    s->vdisk_guid = NULL;
+
+    /*
+     * Close vDisk device
+     */
+    if (s->vdisk_hostinfo.dev_handle) {
+        iio_close(s->vdisk_hostinfo.dev_handle);
+        s->vdisk_hostinfo.dev_handle = NULL;
+    }
+
+    vxhs_unref();
+
+    /*
+     * Free the dynamically allocated host string etc
+     */
+    g_free(s->vdisk_hostinfo.host);
+    g_free(s->tlscredsid);
+    s->tlscredsid = NULL;
+    s->vdisk_hostinfo.host = NULL;
+    s->vdisk_hostinfo.port = 0;
+}
+
+static int64_t vxhs_get_vdisk_stat(BDRVVXHSState *s)
+{
+    int64_t vdisk_size = -1;
+    int ret = 0;
+    void *dev_handle = s->vdisk_hostinfo.dev_handle;
+
+    ret = iio_ioctl(dev_handle, IOR_VDISK_STAT, &vdisk_size, 0);
+    if (ret < 0) {
+        trace_vxhs_get_vdisk_stat_err(s->vdisk_guid, ret, errno);
+        return -EIO;
+    }
+
+    trace_vxhs_get_vdisk_stat(s->vdisk_guid, vdisk_size);
+    return vdisk_size;
+}
+
+/*
+ * Returns the size of vDisk in bytes. This is required
+ * by QEMU block upper block layer so that it is visible
+ * to guest.
+ */
+static int64_t vxhs_getlength(BlockDriverState *bs)
+{
+    BDRVVXHSState *s = bs->opaque;
+    int64_t vdisk_size;
+
+    vdisk_size = vxhs_get_vdisk_stat(s);
+    if (vdisk_size < 0) {
+        return -EIO;
+    }
+
+    return vdisk_size;
+}
+
+static BlockDriver bdrv_vxhs = {
+    .format_name                  = "vxhs",
+    .protocol_name                = "vxhs",
+    .instance_size                = sizeof(BDRVVXHSState),
+    .bdrv_file_open               = vxhs_open,
+    .bdrv_parse_filename          = vxhs_parse_filename,
+    .bdrv_close                   = vxhs_close,
+    .bdrv_getlength               = vxhs_getlength,
+    .bdrv_aio_readv               = vxhs_aio_readv,
+    .bdrv_aio_writev              = vxhs_aio_writev,
+};
+
+static void bdrv_vxhs_init(void)
+{
+    bdrv_register(&bdrv_vxhs);
+}
+
+block_init(bdrv_vxhs_init);