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 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
  50static const XenBackendImpl *xen_backend_table_lookup(const char *type)
  51{
  52    return g_hash_table_lookup(xen_backend_table_get(), type);
  53}
  54
  55void 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
  79const char **xen_backend_get_types(unsigned int *count)
  80{
  81    return xen_backend_table_keys(count);
  82}
  83
  84static QLIST_HEAD(, XenBackendInstance) backend_list;
  85
  86static void xen_backend_list_add(XenBackendInstance *backend)
  87{
  88    QLIST_INSERT_HEAD(&backend_list, backend, entry);
  89}
  90
  91static 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
 104static void xen_backend_list_remove(XenBackendInstance *backend)
 105{
 106    QLIST_REMOVE(backend, entry);
 107}
 108
 109void 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
 135XenBus *xen_backend_get_bus(XenBackendInstance *backend)
 136{
 137    return backend->xenbus;
 138}
 139
 140const char *xen_backend_get_name(XenBackendInstance *backend)
 141{
 142    return backend->name;
 143}
 144
 145void xen_backend_set_device(XenBackendInstance *backend,
 146                            XenDevice *xendev)
 147{
 148    g_assert(!backend->xendev);
 149    backend->xendev = xendev;
 150}
 151
 152XenDevice *xen_backend_get_device(XenBackendInstance *backend)
 153{
 154    return backend->xendev;
 155}
 156
 157
 158bool 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}
 176