backends/hostmem-file.c

   1 /*
   2  * QEMU Host Memory Backend for hugetlbfs
   3  *
   4  * Copyright (C) 2013-2014 Red Hat Inc
   5  *
   6  * Authors:
   7  *   Paolo Bonzini <pbonzini@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12 #include "qemu/osdep.h"
  13 #include "qapi/error.h"
  14 #include "qemu-common.h"
  15 #include "sysemu/hostmem.h"
  16 #include "sysemu/sysemu.h"
  17 #include "qom/object_interfaces.h"
  18
  19 /* hostmem-file.c */
  20 /**
  21  * @TYPE_MEMORY_BACKEND_FILE:
  22  * name of backend that uses mmap on a file descriptor
  23  */
  24 #define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
  25
  26 #define MEMORY_BACKEND_FILE(obj) \
  27     OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
  28
  29 typedef struct HostMemoryBackendFile HostMemoryBackendFile;
  30
  31 struct HostMemoryBackendFile {
  32     HostMemoryBackend parent_obj;
  33
  34     bool share;
  35     bool discard_data;
  36     char *mem_path;
  37     uint64_t align;
  38 };
  39
  40 static void
  41 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  42 {
  43     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  44
  45     if (!backend->size) {
  46         error_setg(errp, "can't create backend with size 0");
  47         return;
  48     }
  49     if (!fb->mem_path) {
  50         error_setg(errp, "mem-path property not set");
  51         return;
  52     }
  53 #ifndef CONFIG_LINUX
  54     error_setg(errp, "-mem-path not supported on this host");
  55 #else
  56     if (!host_memory_backend_mr_inited(backend)) {
  57         gchar *path;
  58         backend->force_prealloc = mem_prealloc;
  59         path = object_get_canonical_path(OBJECT(backend));
  60         memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  61                                  path,
  62                                  backend->size, fb->align, fb->share,
  63                                  fb->mem_path, errp);
  64         g_free(path);
  65     }
  66 #endif
  67 }
  68
  69 static char *get_mem_path(Object *o, Error **errp)
  70 {
  71     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  72
  73     return g_strdup(fb->mem_path);
  74 }
  75
  76 static void set_mem_path(Object *o, const char *str, Error **errp)
  77 {
  78     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  79     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  80
  81     if (host_memory_backend_mr_inited(backend)) {
  82         error_setg(errp, "cannot change property value");
  83         return;
  84     }
  85     g_free(fb->mem_path);
  86     fb->mem_path = g_strdup(str);
  87 }
  88
  89 static bool file_memory_backend_get_share(Object *o, Error **errp)
  90 {
  91     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  92
  93     return fb->share;
  94 }
  95
  96 static void file_memory_backend_set_share(Object *o, bool value, Error **errp)
  97 {
  98     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  99     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 100
 101     if (host_memory_backend_mr_inited(backend)) {
 102         error_setg(errp, "cannot change property value");
 103         return;
 104     }
 105     fb->share = value;
 106 }
 107
 108 static bool file_memory_backend_get_discard_data(Object *o, Error **errp)
 109 {
 110     return MEMORY_BACKEND_FILE(o)->discard_data;
 111 }
 112
 113 static void file_memory_backend_set_discard_data(Object *o, bool value,
 114                                                Error **errp)
 115 {
 116     MEMORY_BACKEND_FILE(o)->discard_data = value;
 117 }
 118
 119 static void file_memory_backend_get_align(Object *o, Visitor *v,
 120                                           const char *name, void *opaque,
 121                                           Error **errp)
 122 {
 123     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 124     uint64_t val = fb->align;
 125
 126     visit_type_size(v, name, &val, errp);
 127 }
 128
 129 static void file_memory_backend_set_align(Object *o, Visitor *v,
 130                                           const char *name, void *opaque,
 131                                           Error **errp)
 132 {
 133     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 134     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 135     Error *local_err = NULL;
 136     uint64_t val;
 137
 138     if (host_memory_backend_mr_inited(backend)) {
 139         error_setg(&local_err, "cannot change property value");
 140         goto out;
 141     }
 142
 143     visit_type_size(v, name, &val, &local_err);
 144     if (local_err) {
 145         goto out;
 146     }
 147     fb->align = val;
 148
 149  out:
 150     error_propagate(errp, local_err);
 151 }
 152
 153 static void file_backend_unparent(Object *obj)
 154 {
 155     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
 156     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
 157
 158     if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
 159         void *ptr = memory_region_get_ram_ptr(&backend->mr);
 160         uint64_t sz = memory_region_size(&backend->mr);
 161
 162         qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
 163     }
 164 }
 165
 166 static void
 167 file_backend_class_init(ObjectClass *oc, void *data)
 168 {
 169     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 170
 171     bc->alloc = file_backend_memory_alloc;
 172     oc->unparent = file_backend_unparent;
 173
 174     object_class_property_add_bool(oc, "share",
 175         file_memory_backend_get_share, file_memory_backend_set_share,
 176         &error_abort);
 177     object_class_property_add_bool(oc, "discard-data",
 178         file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
 179         &error_abort);
 180     object_class_property_add_str(oc, "mem-path",
 181         get_mem_path, set_mem_path,
 182         &error_abort);
 183     object_class_property_add(oc, "align", "int",
 184         file_memory_backend_get_align,
 185         file_memory_backend_set_align,
 186         NULL, NULL, &error_abort);
 187 }
 188
 189 static void file_backend_instance_finalize(Object *o)
 190 {
 191     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 192
 193     g_free(fb->mem_path);
 194 }
 195
 196 static const TypeInfo file_backend_info = {
 197     .name = TYPE_MEMORY_BACKEND_FILE,
 198     .parent = TYPE_MEMORY_BACKEND,
 199     .class_init = file_backend_class_init,
 200     .instance_finalize = file_backend_instance_finalize,
 201     .instance_size = sizeof(HostMemoryBackendFile),
 202 };
 203
 204 static void register_types(void)
 205 {
 206     type_register_static(&file_backend_info);
 207 }
 208
 209 type_init(register_types);