xen: re-name XenDevice to XenLegacyDevice...

...and xen_backend.h to xen-legacy-backend.h

Rather than attempting to convert the existing backend infrastructure to
be QOM compliant (which would be hard to do in an incremental fashion),
subsequent patches will introduce a completely new framework for Xen PV
backends. Hence it is necessary to re-name parts of existing code to avoid
name clashes. The re-named 'legacy' infrastructure will be removed once all
backends have been ported to the new framework.

This patch is purely cosmetic. No functional change.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
diff --git a/hw/xen/xen-legacy-backend.c b/hw/xen/xen-legacy-backend.c
new file mode 100644
index 0000000..4141976
--- /dev/null
+++ b/hw/xen/xen-legacy-backend.c
@@ -0,0 +1,847 @@
+/*
+ *  xen backend driver infrastructure
+ *  (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; under version 2 of the License.
+ *
+ *  This program 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Contributions after 2012-01-13 are licensed under the terms of the
+ *  GNU GPL, version 2 or (at your option) any later version.
+ */
+
+/*
+ * TODO: add some xenbus / xenstore concepts overview here.
+ */
+
+#include "qemu/osdep.h"
+#include <sys/signal.h>
+
+#include "hw/hw.h"
+#include "hw/sysbus.h"
+#include "hw/boards.h"
+#include "qemu/log.h"
+#include "qapi/error.h"
+#include "hw/xen/xen-legacy-backend.h"
+#include "hw/xen/xen_pvdev.h"
+#include "monitor/qdev.h"
+
+#include <xen/grant_table.h>
+
+DeviceState *xen_sysdev;
+BusState *xen_sysbus;
+
+/* ------------------------------------------------------------- */
+
+/* public */
+struct xs_handle *xenstore;
+const char *xen_protocol;
+
+/* private */
+static bool xen_feature_grant_copy;
+static int debug;
+
+int xenstore_write_be_str(struct XenLegacyDevice *xendev, const char *node,
+                          const char *val)
+{
+    return xenstore_write_str(xendev->be, node, val);
+}
+
+int xenstore_write_be_int(struct XenLegacyDevice *xendev, const char *node,
+                          int ival)
+{
+    return xenstore_write_int(xendev->be, node, ival);
+}
+
+int xenstore_write_be_int64(struct XenLegacyDevice *xendev, const char *node,
+                            int64_t ival)
+{
+    return xenstore_write_int64(xendev->be, node, ival);
+}
+
+char *xenstore_read_be_str(struct XenLegacyDevice *xendev, const char *node)
+{
+    return xenstore_read_str(xendev->be, node);
+}
+
+int xenstore_read_be_int(struct XenLegacyDevice *xendev, const char *node,
+                         int *ival)
+{
+    return xenstore_read_int(xendev->be, node, ival);
+}
+
+char *xenstore_read_fe_str(struct XenLegacyDevice *xendev, const char *node)
+{
+    return xenstore_read_str(xendev->fe, node);
+}
+
+int xenstore_read_fe_int(struct XenLegacyDevice *xendev, const char *node,
+                         int *ival)
+{
+    return xenstore_read_int(xendev->fe, node, ival);
+}
+
+int xenstore_read_fe_uint64(struct XenLegacyDevice *xendev, const char *node,
+                            uint64_t *uval)
+{
+    return xenstore_read_uint64(xendev->fe, node, uval);
+}
+
+/* ------------------------------------------------------------- */
+
+int xen_be_set_state(struct XenLegacyDevice *xendev, enum xenbus_state state)
+{
+    int rc;
+
+    rc = xenstore_write_be_int(xendev, "state", state);
+    if (rc < 0) {
+        return rc;
+    }
+    xen_pv_printf(xendev, 1, "backend state: %s -> %s\n",
+                  xenbus_strstate(xendev->be_state), xenbus_strstate(state));
+    xendev->be_state = state;
+    return 0;
+}
+
+void xen_be_set_max_grant_refs(struct XenLegacyDevice *xendev,
+                               unsigned int nr_refs)
+{
+    assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
+
+    if (xengnttab_set_max_grants(xendev->gnttabdev, nr_refs)) {
+        xen_pv_printf(xendev, 0, "xengnttab_set_max_grants failed: %s\n",
+                      strerror(errno));
+    }
+}
+
+void *xen_be_map_grant_refs(struct XenLegacyDevice *xendev, uint32_t *refs,
+                            unsigned int nr_refs, int prot)
+{
+    void *ptr;
+
+    assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
+
+    ptr = xengnttab_map_domain_grant_refs(xendev->gnttabdev, nr_refs,
+                                          xen_domid, refs, prot);
+    if (!ptr) {
+        xen_pv_printf(xendev, 0,
+                      "xengnttab_map_domain_grant_refs failed: %s\n",
+                      strerror(errno));
+    }
+
+    return ptr;
+}
+
+void xen_be_unmap_grant_refs(struct XenLegacyDevice *xendev, void *ptr,
+                             unsigned int nr_refs)
+{
+    assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
+
+    if (xengnttab_unmap(xendev->gnttabdev, ptr, nr_refs)) {
+        xen_pv_printf(xendev, 0, "xengnttab_unmap failed: %s\n",
+                      strerror(errno));
+    }
+}
+
+static int compat_copy_grant_refs(struct XenLegacyDevice *xendev,
+                                  bool to_domain,
+                                  XenGrantCopySegment segs[],
+                                  unsigned int nr_segs)
+{
+    uint32_t *refs = g_new(uint32_t, nr_segs);
+    int prot = to_domain ? PROT_WRITE : PROT_READ;
+    void *pages;
+    unsigned int i;
+
+    for (i = 0; i < nr_segs; i++) {
+        XenGrantCopySegment *seg = &segs[i];
+
+        refs[i] = to_domain ?
+            seg->dest.foreign.ref : seg->source.foreign.ref;
+    }
+
+    pages = xengnttab_map_domain_grant_refs(xendev->gnttabdev, nr_segs,
+                                            xen_domid, refs, prot);
+    if (!pages) {
+        xen_pv_printf(xendev, 0,
+                      "xengnttab_map_domain_grant_refs failed: %s\n",
+                      strerror(errno));
+        g_free(refs);
+        return -1;
+    }
+
+    for (i = 0; i < nr_segs; i++) {
+        XenGrantCopySegment *seg = &segs[i];
+        void *page = pages + (i * XC_PAGE_SIZE);
+
+        if (to_domain) {
+            memcpy(page + seg->dest.foreign.offset, seg->source.virt,
+                   seg->len);
+        } else {
+            memcpy(seg->dest.virt, page + seg->source.foreign.offset,
+                   seg->len);
+        }
+    }
+
+    if (xengnttab_unmap(xendev->gnttabdev, pages, nr_segs)) {
+        xen_pv_printf(xendev, 0, "xengnttab_unmap failed: %s\n",
+                      strerror(errno));
+    }
+
+    g_free(refs);
+    return 0;
+}
+
+int xen_be_copy_grant_refs(struct XenLegacyDevice *xendev,
+                           bool to_domain,
+                           XenGrantCopySegment segs[],
+                           unsigned int nr_segs)
+{
+    xengnttab_grant_copy_segment_t *xengnttab_segs;
+    unsigned int i;
+    int rc;
+
+    assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
+
+    if (!xen_feature_grant_copy) {
+        return compat_copy_grant_refs(xendev, to_domain, segs, nr_segs);
+    }
+
+    xengnttab_segs = g_new0(xengnttab_grant_copy_segment_t, nr_segs);
+
+    for (i = 0; i < nr_segs; i++) {
+        XenGrantCopySegment *seg = &segs[i];
+        xengnttab_grant_copy_segment_t *xengnttab_seg = &xengnttab_segs[i];
+
+        if (to_domain) {
+            xengnttab_seg->flags = GNTCOPY_dest_gref;
+            xengnttab_seg->dest.foreign.domid = xen_domid;
+            xengnttab_seg->dest.foreign.ref = seg->dest.foreign.ref;
+            xengnttab_seg->dest.foreign.offset = seg->dest.foreign.offset;
+            xengnttab_seg->source.virt = seg->source.virt;
+        } else {
+            xengnttab_seg->flags = GNTCOPY_source_gref;
+            xengnttab_seg->source.foreign.domid = xen_domid;
+            xengnttab_seg->source.foreign.ref = seg->source.foreign.ref;
+            xengnttab_seg->source.foreign.offset =
+                seg->source.foreign.offset;
+            xengnttab_seg->dest.virt = seg->dest.virt;
+        }
+
+        xengnttab_seg->len = seg->len;
+    }
+
+    rc = xengnttab_grant_copy(xendev->gnttabdev, nr_segs, xengnttab_segs);
+
+    if (rc) {
+        xen_pv_printf(xendev, 0, "xengnttab_copy failed: %s\n",
+                      strerror(errno));
+    }
+
+    for (i = 0; i < nr_segs; i++) {
+        xengnttab_grant_copy_segment_t *xengnttab_seg =
+            &xengnttab_segs[i];
+
+        if (xengnttab_seg->status != GNTST_okay) {
+            xen_pv_printf(xendev, 0, "segment[%u] status: %d\n", i,
+                          xengnttab_seg->status);
+            rc = -1;
+        }
+    }
+
+    g_free(xengnttab_segs);
+    return rc;
+}
+
+/*
+ * get xen backend device, allocate a new one if it doesn't exist.
+ */
+static struct XenLegacyDevice *xen_be_get_xendev(const char *type, int dom,
+                                                 int dev,
+                                                 struct XenDevOps *ops)
+{
+    struct XenLegacyDevice *xendev;
+
+    xendev = xen_pv_find_xendev(type, dom, dev);
+    if (xendev) {
+        return xendev;
+    }
+
+    /* init new xendev */
+    xendev = g_malloc0(ops->size);
+    object_initialize(&xendev->qdev, ops->size, TYPE_XENBACKEND);
+    OBJECT(xendev)->free = g_free;
+    qdev_set_parent_bus(DEVICE(xendev), xen_sysbus);
+    qdev_set_id(DEVICE(xendev), g_strdup_printf("xen-%s-%d", type, dev));
+    qdev_init_nofail(DEVICE(xendev));
+    object_unref(OBJECT(xendev));
+
+    xendev->type  = type;
+    xendev->dom   = dom;
+    xendev->dev   = dev;
+    xendev->ops   = ops;
+
+    snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
+             xendev->type, xendev->dom, xendev->dev);
+    snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
+             xendev->type, xendev->dev);
+
+    xendev->debug      = debug;
+    xendev->local_port = -1;
+
+    xendev->evtchndev = xenevtchn_open(NULL, 0);
+    if (xendev->evtchndev == NULL) {
+        xen_pv_printf(NULL, 0, "can't open evtchn device\n");
+        qdev_unplug(DEVICE(xendev), NULL);
+        return NULL;
+    }
+    qemu_set_cloexec(xenevtchn_fd(xendev->evtchndev));
+
+    xen_pv_insert_xendev(xendev);
+
+    if (xendev->ops->alloc) {
+        xendev->ops->alloc(xendev);
+    }
+
+    return xendev;
+}
+
+
+/*
+ * Sync internal data structures on xenstore updates.
+ * Node specifies the changed field.  node = NULL means
+ * update all fields (used for initialization).
+ */
+static void xen_be_backend_changed(struct XenLegacyDevice *xendev,
+                                   const char *node)
+{
+    if (node == NULL  ||  strcmp(node, "online") == 0) {
+        if (xenstore_read_be_int(xendev, "online", &xendev->online) == -1) {
+            xendev->online = 0;
+        }
+    }
+
+    if (node) {
+        xen_pv_printf(xendev, 2, "backend update: %s\n", node);
+        if (xendev->ops->backend_changed) {
+            xendev->ops->backend_changed(xendev, node);
+        }
+    }
+}
+
+static void xen_be_frontend_changed(struct XenLegacyDevice *xendev,
+                                    const char *node)
+{
+    int fe_state;
+
+    if (node == NULL  ||  strcmp(node, "state") == 0) {
+        if (xenstore_read_fe_int(xendev, "state", &fe_state) == -1) {
+            fe_state = XenbusStateUnknown;
+        }
+        if (xendev->fe_state != fe_state) {
+            xen_pv_printf(xendev, 1, "frontend state: %s -> %s\n",
+                          xenbus_strstate(xendev->fe_state),
+                          xenbus_strstate(fe_state));
+        }
+        xendev->fe_state = fe_state;
+    }
+    if (node == NULL  ||  strcmp(node, "protocol") == 0) {
+        g_free(xendev->protocol);
+        xendev->protocol = xenstore_read_fe_str(xendev, "protocol");
+        if (xendev->protocol) {
+            xen_pv_printf(xendev, 1, "frontend protocol: %s\n",
+                          xendev->protocol);
+        }
+    }
+
+    if (node) {
+        xen_pv_printf(xendev, 2, "frontend update: %s\n", node);
+        if (xendev->ops->frontend_changed) {
+            xendev->ops->frontend_changed(xendev, node);
+        }
+    }
+}
+
+/* ------------------------------------------------------------- */
+/* Check for possible state transitions and perform them.        */
+
+/*
+ * Initial xendev setup.  Read frontend path, register watch for it.
+ * Should succeed once xend finished setting up the backend device.
+ *
+ * Also sets initial state (-> Initializing) when done.  Which
+ * only affects the xendev->be_state variable as xenbus should
+ * already be put into that state by xend.
+ */
+static int xen_be_try_setup(struct XenLegacyDevice *xendev)
+{
+    char token[XEN_BUFSIZE];
+    int be_state;
+
+    if (xenstore_read_be_int(xendev, "state", &be_state) == -1) {
+        xen_pv_printf(xendev, 0, "reading backend state failed\n");
+        return -1;
+    }
+
+    if (be_state != XenbusStateInitialising) {
+        xen_pv_printf(xendev, 0, "initial backend state is wrong (%s)\n",
+                      xenbus_strstate(be_state));
+        return -1;
+    }
+
+    xendev->fe = xenstore_read_be_str(xendev, "frontend");
+    if (xendev->fe == NULL) {
+        xen_pv_printf(xendev, 0, "reading frontend path failed\n");
+        return -1;
+    }
+
+    /* setup frontend watch */
+    snprintf(token, sizeof(token), "fe:%p", xendev);
+    if (!xs_watch(xenstore, xendev->fe, token)) {
+        xen_pv_printf(xendev, 0, "watching frontend path (%s) failed\n",
+                      xendev->fe);
+        return -1;
+    }
+    xen_be_set_state(xendev, XenbusStateInitialising);
+
+    xen_be_backend_changed(xendev, NULL);
+    xen_be_frontend_changed(xendev, NULL);
+    return 0;
+}
+
+/*
+ * Try initialize xendev.  Prepare everything the backend can do
+ * without synchronizing with the frontend.  Fakes hotplug-status.  No
+ * hotplug involved here because this is about userspace drivers, thus
+ * there are kernel backend devices which could invoke hotplug.
+ *
+ * Goes to InitWait on success.
+ */
+static int xen_be_try_init(struct XenLegacyDevice *xendev)
+{
+    int rc = 0;
+
+    if (!xendev->online) {
+        xen_pv_printf(xendev, 1, "not online\n");
+        return -1;
+    }
+
+    if (xendev->ops->init) {
+        rc = xendev->ops->init(xendev);
+    }
+    if (rc != 0) {
+        xen_pv_printf(xendev, 1, "init() failed\n");
+        return rc;
+    }
+
+    xenstore_write_be_str(xendev, "hotplug-status", "connected");
+    xen_be_set_state(xendev, XenbusStateInitWait);
+    return 0;
+}
+
+/*
+ * Try to initialise xendev.  Depends on the frontend being ready
+ * for it (shared ring and evtchn info in xenstore, state being
+ * Initialised or Connected).
+ *
+ * Goes to Connected on success.
+ */
+static int xen_be_try_initialise(struct XenLegacyDevice *xendev)
+{
+    int rc = 0;
+
+    if (xendev->fe_state != XenbusStateInitialised  &&
+        xendev->fe_state != XenbusStateConnected) {
+        if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
+            xen_pv_printf(xendev, 2, "frontend not ready, ignoring\n");
+        } else {
+            xen_pv_printf(xendev, 2, "frontend not ready (yet)\n");
+            return -1;
+        }
+    }
+
+    if (xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
+        xendev->gnttabdev = xengnttab_open(NULL, 0);
+        if (xendev->gnttabdev == NULL) {
+            xen_pv_printf(NULL, 0, "can't open gnttab device\n");
+            return -1;
+        }
+    } else {
+        xendev->gnttabdev = NULL;
+    }
+
+    if (xendev->ops->initialise) {
+        rc = xendev->ops->initialise(xendev);
+    }
+    if (rc != 0) {
+        xen_pv_printf(xendev, 0, "initialise() failed\n");
+        return rc;
+    }
+
+    xen_be_set_state(xendev, XenbusStateConnected);
+    return 0;
+}
+
+/*
+ * Try to let xendev know that it is connected.  Depends on the
+ * frontend being Connected.  Note that this may be called more
+ * than once since the backend state is not modified.
+ */
+static void xen_be_try_connected(struct XenLegacyDevice *xendev)
+{
+    if (!xendev->ops->connected) {
+        return;
+    }
+
+    if (xendev->fe_state != XenbusStateConnected) {
+        if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
+            xen_pv_printf(xendev, 2, "frontend not ready, ignoring\n");
+        } else {
+            xen_pv_printf(xendev, 2, "frontend not ready (yet)\n");
+            return;
+        }
+    }
+
+    xendev->ops->connected(xendev);
+}
+
+/*
+ * Teardown connection.
+ *
+ * Goes to Closed when done.
+ */
+static void xen_be_disconnect(struct XenLegacyDevice *xendev,
+                              enum xenbus_state state)
+{
+    if (xendev->be_state != XenbusStateClosing &&
+        xendev->be_state != XenbusStateClosed  &&
+        xendev->ops->disconnect) {
+        xendev->ops->disconnect(xendev);
+    }
+    if (xendev->gnttabdev) {
+        xengnttab_close(xendev->gnttabdev);
+        xendev->gnttabdev = NULL;
+    }
+    if (xendev->be_state != state) {
+        xen_be_set_state(xendev, state);
+    }
+}
+
+/*
+ * Try to reset xendev, for reconnection by another frontend instance.
+ */
+static int xen_be_try_reset(struct XenLegacyDevice *xendev)
+{
+    if (xendev->fe_state != XenbusStateInitialising) {
+        return -1;
+    }
+
+    xen_pv_printf(xendev, 1, "device reset (for re-connect)\n");
+    xen_be_set_state(xendev, XenbusStateInitialising);
+    return 0;
+}
+
+/*
+ * state change dispatcher function
+ */
+void xen_be_check_state(struct XenLegacyDevice *xendev)
+{
+    int rc = 0;
+
+    /* frontend may request shutdown from almost anywhere */
+    if (xendev->fe_state == XenbusStateClosing ||
+        xendev->fe_state == XenbusStateClosed) {
+        xen_be_disconnect(xendev, xendev->fe_state);
+        return;
+    }
+
+    /* check for possible backend state transitions */
+    for (;;) {
+        switch (xendev->be_state) {
+        case XenbusStateUnknown:
+            rc = xen_be_try_setup(xendev);
+            break;
+        case XenbusStateInitialising:
+            rc = xen_be_try_init(xendev);
+            break;
+        case XenbusStateInitWait:
+            rc = xen_be_try_initialise(xendev);
+            break;
+        case XenbusStateConnected:
+            /* xendev->be_state doesn't change */
+            xen_be_try_connected(xendev);
+            rc = -1;
+            break;
+        case XenbusStateClosed:
+            rc = xen_be_try_reset(xendev);
+            break;
+        default:
+            rc = -1;
+        }
+        if (rc != 0) {
+            break;
+        }
+    }
+}
+
+/* ------------------------------------------------------------- */
+
+static int xenstore_scan(const char *type, int dom, struct XenDevOps *ops)
+{
+    struct XenLegacyDevice *xendev;
+    char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
+    char **dev = NULL;
+    unsigned int cdev, j;
+
+    /* setup watch */
+    snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
+    snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
+    if (!xs_watch(xenstore, path, token)) {
+        xen_pv_printf(NULL, 0, "xen be: watching backend path (%s) failed\n",
+                      path);
+        return -1;
+    }
+
+    /* look for backends */
+    dev = xs_directory(xenstore, 0, path, &cdev);
+    if (!dev) {
+        return 0;
+    }
+    for (j = 0; j < cdev; j++) {
+        xendev = xen_be_get_xendev(type, dom, atoi(dev[j]), ops);
+        if (xendev == NULL) {
+            continue;
+        }
+        xen_be_check_state(xendev);
+    }
+    free(dev);
+    return 0;
+}
+
+void xenstore_update_be(char *watch, char *type, int dom,
+                        struct XenDevOps *ops)
+{
+    struct XenLegacyDevice *xendev;
+    char path[XEN_BUFSIZE], *bepath;
+    unsigned int len, dev;
+
+    len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
+    if (strncmp(path, watch, len) != 0) {
+        return;
+    }
+    if (sscanf(watch + len, "/%u/%255s", &dev, path) != 2) {
+        strcpy(path, "");
+        if (sscanf(watch + len, "/%u", &dev) != 1) {
+            dev = -1;
+        }
+    }
+    if (dev == -1) {
+        return;
+    }
+
+    xendev = xen_be_get_xendev(type, dom, dev, ops);
+    if (xendev != NULL) {
+        bepath = xs_read(xenstore, 0, xendev->be, &len);
+        if (bepath == NULL) {
+            xen_pv_del_xendev(xendev);
+        } else {
+            free(bepath);
+            xen_be_backend_changed(xendev, path);
+            xen_be_check_state(xendev);
+        }
+    }
+}
+
+void xenstore_update_fe(char *watch, struct XenLegacyDevice *xendev)
+{
+    char *node;
+    unsigned int len;
+
+    len = strlen(xendev->fe);
+    if (strncmp(xendev->fe, watch, len) != 0) {
+        return;
+    }
+    if (watch[len] != '/') {
+        return;
+    }
+    node = watch + len + 1;
+
+    xen_be_frontend_changed(xendev, node);
+    xen_be_check_state(xendev);
+}
+/* -------------------------------------------------------------------- */
+
+int xen_be_init(void)
+{
+    xengnttab_handle *gnttabdev;
+
+    xenstore = xs_daemon_open();
+    if (!xenstore) {
+        xen_pv_printf(NULL, 0, "can't connect to xenstored\n");
+        return -1;
+    }
+
+    qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL);
+
+    if (xen_xc == NULL || xen_fmem == NULL) {
+        /* Check if xen_init() have been called */
+        goto err;
+    }
+
+    gnttabdev = xengnttab_open(NULL, 0);
+    if (gnttabdev != NULL) {
+        if (xengnttab_grant_copy(gnttabdev, 0, NULL) == 0) {
+            xen_feature_grant_copy = true;
+        }
+        xengnttab_close(gnttabdev);
+    }
+
+    xen_sysdev = qdev_create(NULL, TYPE_XENSYSDEV);
+    qdev_init_nofail(xen_sysdev);
+    xen_sysbus = qbus_create(TYPE_XENSYSBUS, DEVICE(xen_sysdev), "xen-sysbus");
+    qbus_set_bus_hotplug_handler(xen_sysbus, &error_abort);
+
+    return 0;
+
+err:
+    qemu_set_fd_handler(xs_fileno(xenstore), NULL, NULL, NULL);
+    xs_daemon_close(xenstore);
+    xenstore = NULL;
+
+    return -1;
+}
+
+static void xen_set_dynamic_sysbus(void)
+{
+    Object *machine = qdev_get_machine();
+    ObjectClass *oc = object_get_class(machine);
+    MachineClass *mc = MACHINE_CLASS(oc);
+
+    machine_class_allow_dynamic_sysbus_dev(mc, TYPE_XENSYSDEV);
+}
+
+int xen_be_register(const char *type, struct XenDevOps *ops)
+{
+    char path[50];
+    int rc;
+
+    if (ops->backend_register) {
+        rc = ops->backend_register();
+        if (rc) {
+            return rc;
+        }
+    }
+
+    snprintf(path, sizeof(path), "device-model/%u/backends/%s", xen_domid,
+             type);
+    xenstore_mkdir(path, XS_PERM_NONE);
+
+    return xenstore_scan(type, xen_domid, ops);
+}
+
+void xen_be_register_common(void)
+{
+    xen_set_dynamic_sysbus();
+
+    xen_be_register("console", &xen_console_ops);
+    xen_be_register("vkbd", &xen_kbdmouse_ops);
+    xen_be_register("qdisk", &xen_blkdev_ops);
+#ifdef CONFIG_VIRTFS
+    xen_be_register("9pfs", &xen_9pfs_ops);
+#endif
+#ifdef CONFIG_USB_LIBUSB
+    xen_be_register("qusb", &xen_usb_ops);
+#endif
+}
+
+int xen_be_bind_evtchn(struct XenLegacyDevice *xendev)
+{
+    if (xendev->local_port != -1) {
+        return 0;
+    }
+    xendev->local_port = xenevtchn_bind_interdomain
+        (xendev->evtchndev, xendev->dom, xendev->remote_port);
+    if (xendev->local_port == -1) {
+        xen_pv_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
+        return -1;
+    }
+    xen_pv_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
+    qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
+                        xen_pv_evtchn_event, NULL, xendev);
+    return 0;
+}
+
+
+static Property xendev_properties[] = {
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void xendev_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = xendev_properties;
+    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
+    /* xen-backend devices can be plugged/unplugged dynamically */
+    dc->user_creatable = true;
+}
+
+static const TypeInfo xendev_type_info = {
+    .name          = TYPE_XENBACKEND,
+    .parent        = TYPE_XENSYSDEV,
+    .class_init    = xendev_class_init,
+    .instance_size = sizeof(struct XenLegacyDevice),
+};
+
+static void xen_sysbus_class_init(ObjectClass *klass, void *data)
+{
+    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
+
+    hc->unplug = qdev_simple_device_unplug_cb;
+}
+
+static const TypeInfo xensysbus_info = {
+    .name       = TYPE_XENSYSBUS,
+    .parent     = TYPE_BUS,
+    .class_init = xen_sysbus_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_HOTPLUG_HANDLER },
+        { }
+    }
+};
+
+static Property xen_sysdev_properties[] = {
+    {/* end of property list */},
+};
+
+static void xen_sysdev_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = xen_sysdev_properties;
+    dc->bus_type = TYPE_XENSYSBUS;
+}
+
+static const TypeInfo xensysdev_info = {
+    .name          = TYPE_XENSYSDEV,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(SysBusDevice),
+    .class_init    = xen_sysdev_class_init,
+};
+
+static void xenbe_register_types(void)
+{
+    type_register_static(&xensysbus_info);
+    type_register_static(&xensysdev_info);
+    type_register_static(&xendev_type_info);
+}
+
+type_init(xenbe_register_types)