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xen-backend.c (3935B)

      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 }