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 bool xen_backend_exists(const char *type, const char *name)
 105 {
 106     const XenBackendImpl *impl = xen_backend_table_lookup(type);
 107     XenBackendInstance *backend;
 108
 109     if (!impl) {
 110         return false;
 111     }
 112
 113     QLIST_FOREACH(backend, &backend_list, entry) {
 114         if (backend->impl == impl && !strcmp(backend->name, name)) {
 115             return true;
 116         }
 117     }
 118
 119     return false;
 120 }
 121
 122 static void xen_backend_list_remove(XenBackendInstance *backend)
 123 {
 124     QLIST_REMOVE(backend, entry);
 125 }
 126
 127 void xen_backend_device_create(XenBus *xenbus, const char *type,
 128                                const char *name, QDict *opts, Error **errp)
 129 {
 130     ERRP_GUARD();
 131     const XenBackendImpl *impl = xen_backend_table_lookup(type);
 132     XenBackendInstance *backend;
 133
 134     if (!impl) {
 135         return;
 136     }
 137
 138     backend = g_new0(XenBackendInstance, 1);
 139     backend->xenbus = xenbus;
 140     backend->name = g_strdup(name);
 141
 142     impl->create(backend, opts, errp);
 143
 144     backend->impl = impl;
 145     xen_backend_list_add(backend);
 146 }
 147
 148 XenBus *xen_backend_get_bus(XenBackendInstance *backend)
 149 {
 150     return backend->xenbus;
 151 }
 152
 153 const char *xen_backend_get_name(XenBackendInstance *backend)
 154 {
 155     return backend->name;
 156 }
 157
 158 void xen_backend_set_device(XenBackendInstance *backend,
 159                             XenDevice *xendev)
 160 {
 161     g_assert(!backend->xendev);
 162     backend->xendev = xendev;
 163 }
 164
 165 XenDevice *xen_backend_get_device(XenBackendInstance *backend)
 166 {
 167     return backend->xendev;
 168 }
 169
 170
 171 bool xen_backend_try_device_destroy(XenDevice *xendev, Error **errp)
 172 {
 173     XenBackendInstance *backend = xen_backend_list_find(xendev);
 174     const XenBackendImpl *impl;
 175
 176     if (!backend) {
 177         return false;
 178     }
 179
 180     impl = backend->impl;
 181     if (backend->xendev) {
 182         impl->destroy(backend, errp);
 183     }
 184
 185     xen_backend_list_remove(backend);
 186     g_free(backend->name);
 187     g_free(backend);
 188
 189     return true;
 190 }