LXR qemu/hw/xen/xen-backend.c

   1/*
   2 * Copyright (c) 2018  Citrix Systems Inc.
   3 *
   4 * This work is licensed under the terms of the GNU GPL, version 2 or later.
   5 * See the COPYING file in the top-level directory.
   6 */
   7
   8#include "qemu/osdep.h"
   9#include "qemu/error-report.h"
  10#include "qapi/error.h"
  11#include "hw/xen/xen-backend.h"
  12#include "hw/xen/xen-bus.h"
  13
  14typedef struct XenBackendImpl {
  15    const char *type;
  16    XenBackendDeviceCreate create;
  17    XenBackendDeviceDestroy destroy;
  18} XenBackendImpl;
  19
  20struct XenBackendInstance {
  21    QLIST_ENTRY(XenBackendInstance) entry;
  22    const XenBackendImpl *impl;
  23    XenBus *xenbus;
  24    char *name;
  25    XenDevice *xendev;
  26};
  27
  28static GHashTable *xen_backend_table_get(void)
  29{
  30    static GHashTable *table;
  31
  32    if (table == NULL) {
  33        table = g_hash_table_new(g_str_hash, g_str_equal);
  34    }
  35
  36    return table;
  37}
  38
  39static void xen_backend_table_add(XenBackendImpl *impl)
  40{
  41    g_hash_table_insert(xen_backend_table_get(), (void *)impl->type, impl);
  42}
  43
  44static const XenBackendImpl *xen_backend_table_lookup(const char *type)
  45{
  46    return g_hash_table_lookup(xen_backend_table_get(), type);
  47}
  48
  49void xen_backend_register(const XenBackendInfo *info)
  50{
  51    XenBackendImpl *impl = g_new0(XenBackendImpl, 1);
  52
  53    g_assert(info->type);
  54
  55    if (xen_backend_table_lookup(info->type)) {
  56        error_report("attempt to register duplicate Xen backend type '%s'",
  57                     info->type);
  58        abort();
  59    }
  60
  61    if (!info->create) {
  62        error_report("backend type '%s' has no creator", info->type);
  63        abort();
  64    }
  65
  66    impl->type = info->type;
  67    impl->create = info->create;
  68    impl->destroy = info->destroy;
  69
  70    xen_backend_table_add(impl);
  71}
  72
  73static QLIST_HEAD(, XenBackendInstance) backend_list;
  74
  75static void xen_backend_list_add(XenBackendInstance *backend)
  76{
  77    QLIST_INSERT_HEAD(&backend_list, backend, entry);
  78}
  79
  80static XenBackendInstance *xen_backend_list_find(XenDevice *xendev)
  81{
  82    XenBackendInstance *backend;
  83
  84    QLIST_FOREACH(backend, &backend_list, entry) {
  85        if (backend->xendev == xendev) {
  86            return backend;
  87        }
  88    }
  89
  90    return NULL;
  91}
  92
  93static void xen_backend_list_remove(XenBackendInstance *backend)
  94{
  95    QLIST_REMOVE(backend, entry);
  96}
  97
  98void xen_backend_device_create(XenBus *xenbus, const char *type,
  99                               const char *name, QDict *opts, Error **errp)
 100{
 101    ERRP_GUARD();
 102    const XenBackendImpl *impl = xen_backend_table_lookup(type);
 103    XenBackendInstance *backend;
 104
 105    if (!impl) {
 106        return;
 107    }
 108
 109    backend = g_new0(XenBackendInstance, 1);
 110    backend->xenbus = xenbus;
 111    backend->name = g_strdup(name);
 112
 113    impl->create(backend, opts, errp);
 114    if (*errp) {
 115        g_free(backend->name);
 116        g_free(backend);
 117        return;
 118    }
 119
 120    backend->impl = impl;
 121    xen_backend_list_add(backend);
 122}
 123
 124XenBus *xen_backend_get_bus(XenBackendInstance *backend)
 125{
 126    return backend->xenbus;
 127}
 128
 129const char *xen_backend_get_name(XenBackendInstance *backend)
 130{
 131    return backend->name;
 132}
 133
 134void xen_backend_set_device(XenBackendInstance *backend,
 135                            XenDevice *xendev)
 136{
 137    g_assert(!backend->xendev);
 138    backend->xendev = xendev;
 139}
 140
 141XenDevice *xen_backend_get_device(XenBackendInstance *backend)
 142{
 143    return backend->xendev;
 144}
 145
 146
 147bool xen_backend_try_device_destroy(XenDevice *xendev, Error **errp)
 148{
 149    XenBackendInstance *backend = xen_backend_list_find(xendev);
 150    const XenBackendImpl *impl;
 151
 152    if (!backend) {
 153        return false;
 154    }
 155
 156    impl = backend->impl;
 157    impl->destroy(backend, errp);
 158
 159    xen_backend_list_remove(backend);
 160    g_free(backend->name);
 161    g_free(backend);
 162
 163    return true;
 164}
 165