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 XenBackendImpl *xen_backend_table_lookup(const char *type)
  45 {
  46     return g_hash_table_lookup(xen_backend_table_get(), type);
  47 }
  48
  49 void 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
  73 static QLIST_HEAD(, XenBackendInstance) backend_list;
  74
  75 static void xen_backend_list_add(XenBackendInstance *backend)
  76 {
  77     QLIST_INSERT_HEAD(&backend_list, backend, entry);
  78 }
  79
  80 static 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
  93 static void xen_backend_list_remove(XenBackendInstance *backend)
  94 {
  95     QLIST_REMOVE(backend, entry);
  96 }
  97
  98 void 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
 124 XenBus *xen_backend_get_bus(XenBackendInstance *backend)
 125 {
 126     return backend->xenbus;
 127 }
 128
 129 const char *xen_backend_get_name(XenBackendInstance *backend)
 130 {
 131     return backend->name;
 132 }
 133
 134 void xen_backend_set_device(XenBackendInstance *backend,
 135                             XenDevice *xendev)
 136 {
 137     g_assert(!backend->xendev);
 138     backend->xendev = xendev;
 139 }
 140
 141 XenDevice *xen_backend_get_device(XenBackendInstance *backend)
 142 {
 143     return backend->xendev;
 144 }
 145
 146
 147 bool 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 }