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
  14 typedef struct XenBackendImpl {
  15     const char *type;
  16     XenBackendDeviceCreate create;
  17     XenBackendDeviceDestroy destroy;
  18 } XenBackendImpl;
  19
  20 struct XenBackendInstance {
  21     QLIST_ENTRY(XenBackendInstance) entry;
  22     const XenBackendImpl *impl;
  23     XenBus *xenbus;
  24     char *name;
  25     XenDevice *xendev;
  26 };
  27
  28 static 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
  39 static void xen_backend_table_add(XenBackendImpl *impl)
  40 {
  41     g_hash_table_insert(xen_backend_table_get(), (void *)impl->type, impl);
  42 }
  43
  44 static const char **xen_backend_table_keys(unsigned int *count)
  45 {
  46     return (const char **)g_hash_table_get_keys_as_array(
  47         xen_backend_table_get(), count);
  48 }
  49
  50 static const XenBackendImpl *xen_backend_table_lookup(const char *type)
  51 {
  52     return g_hash_table_lookup(xen_backend_table_get(), type);
  53 }
  54
  55 void xen_backend_register(const XenBackendInfo *info)
  56 {
  57     XenBackendImpl *impl = g_new0(XenBackendImpl, 1);
  58
  59     g_assert(info->type);
  60
  61     if (xen_backend_table_lookup(info->type)) {
  62         error_report("attempt to register duplicate Xen backend type '%s'",
  63                      info->type);
  64         abort();
  65     }
  66
  67     if (!info->create) {
  68         error_report("backend type '%s' has no creator", info->type);
  69         abort();
  70     }
  71
  72     impl->type = info->type;
  73     impl->create = info->create;
  74     impl->destroy = info->destroy;
  75
  76     xen_backend_table_add(impl);
  77 }
  78
  79 const char **xen_backend_get_types(unsigned int *count)
  80 {
  81     return xen_backend_table_keys(count);
  82 }
  83
  84 static QLIST_HEAD(, XenBackendInstance) backend_list;
  85
  86 static void xen_backend_list_add(XenBackendInstance *backend)
  87 {
  88     QLIST_INSERT_HEAD(&backend_list, backend, entry);
  89 }
  90
  91 static XenBackendInstance *xen_backend_list_find(XenDevice *xendev)
  92 {
  93     XenBackendInstance *backend;
  94
  95     QLIST_FOREACH(backend, &backend_list, entry) {
  96         if (backend->xendev == xendev) {
  97             return backend;
  98         }
  99     }
 100
 101     return NULL;
 102 }
 103
 104 static void xen_backend_list_remove(XenBackendInstance *backend)
 105 {
 106     QLIST_REMOVE(backend, entry);
 107 }
 108
 109 void xen_backend_device_create(XenBus *xenbus, const char *type,
 110                                const char *name, QDict *opts, Error **errp)
 111 {
 112     ERRP_GUARD();
 113     const XenBackendImpl *impl = xen_backend_table_lookup(type);
 114     XenBackendInstance *backend;
 115
 116     if (!impl) {
 117         return;
 118     }
 119
 120     backend = g_new0(XenBackendInstance, 1);
 121     backend->xenbus = xenbus;
 122     backend->name = g_strdup(name);
 123
 124     impl->create(backend, opts, errp);
 125     if (*errp) {
 126         g_free(backend->name);
 127         g_free(backend);
 128         return;
 129     }
 130
 131     backend->impl = impl;
 132     xen_backend_list_add(backend);
 133 }
 134
 135 XenBus *xen_backend_get_bus(XenBackendInstance *backend)
 136 {
 137     return backend->xenbus;
 138 }
 139
 140 const char *xen_backend_get_name(XenBackendInstance *backend)
 141 {
 142     return backend->name;
 143 }
 144
 145 void xen_backend_set_device(XenBackendInstance *backend,
 146                             XenDevice *xendev)
 147 {
 148     g_assert(!backend->xendev);
 149     backend->xendev = xendev;
 150 }
 151
 152 XenDevice *xen_backend_get_device(XenBackendInstance *backend)
 153 {
 154     return backend->xendev;
 155 }
 156
 157
 158 bool xen_backend_try_device_destroy(XenDevice *xendev, Error **errp)
 159 {
 160     XenBackendInstance *backend = xen_backend_list_find(xendev);
 161     const XenBackendImpl *impl;
 162
 163     if (!backend) {
 164         return false;
 165     }
 166
 167     impl = backend->impl;
 168     impl->destroy(backend, errp);
 169
 170     xen_backend_list_remove(backend);
 171     g_free(backend->name);
 172     g_free(backend);
 173
 174     return true;
 175 }