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
  13 #include "qemu/osdep.h"
  14 #include "qapi/error.h"
  15 #include "qemu/error-report.h"
  16 #include "qemu/module.h"
  17 #include "sysemu/hostmem.h"
  18 #include "sysemu/sysemu.h"
  19 #include "qom/object_interfaces.h"
  20
  21 /* hostmem-file.c */
  22 /**
  23  * @TYPE_MEMORY_BACKEND_FILE:
  24  * name of backend that uses mmap on a file descriptor
  25  */
  26 #define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
  27
  28 #define MEMORY_BACKEND_FILE(obj) \
  29     OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
  30
  31 typedef struct HostMemoryBackendFile HostMemoryBackendFile;
  32
  33 struct HostMemoryBackendFile {
  34     HostMemoryBackend parent_obj;
  35
  36     char *mem_path;
  37     uint64_t align;
  38     bool discard_data;
  39     bool is_pmem;
  40 };
  41
  42 static void
  43 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  44 {
  45 #ifndef CONFIG_POSIX
  46     error_setg(errp, "backend '%s' not supported on this host",
  47                object_get_typename(OBJECT(backend)));
  48 #else
  49     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  50     gchar *name;
  51
  52     if (!backend->size) {
  53         error_setg(errp, "can't create backend with size 0");
  54         return;
  55     }
  56     if (!fb->mem_path) {
  57         error_setg(errp, "mem-path property not set");
  58         return;
  59     }
  60
  61     backend->force_prealloc = mem_prealloc;
  62     name = host_memory_backend_get_name(backend);
  63     memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  64                                      name,
  65                                      backend->size, fb->align,
  66                                      (backend->share ? RAM_SHARED : 0) |
  67                                      (fb->is_pmem ? RAM_PMEM : 0),
  68                                      fb->mem_path, errp);
  69     g_free(name);
  70 #endif
  71 }
  72
  73 static char *get_mem_path(Object *o, Error **errp)
  74 {
  75     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  76
  77     return g_strdup(fb->mem_path);
  78 }
  79
  80 static void set_mem_path(Object *o, const char *str, Error **errp)
  81 {
  82     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  83     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  84
  85     if (host_memory_backend_mr_inited(backend)) {
  86         error_setg(errp, "cannot change property 'mem-path' of %s",
  87                    object_get_typename(o));
  88         return;
  89     }
  90     g_free(fb->mem_path);
  91     fb->mem_path = g_strdup(str);
  92 }
  93
  94 static bool file_memory_backend_get_discard_data(Object *o, Error **errp)
  95 {
  96     return MEMORY_BACKEND_FILE(o)->discard_data;
  97 }
  98
  99 static void file_memory_backend_set_discard_data(Object *o, bool value,
 100                                                Error **errp)
 101 {
 102     MEMORY_BACKEND_FILE(o)->discard_data = value;
 103 }
 104
 105 static void file_memory_backend_get_align(Object *o, Visitor *v,
 106                                           const char *name, void *opaque,
 107                                           Error **errp)
 108 {
 109     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 110     uint64_t val = fb->align;
 111
 112     visit_type_size(v, name, &val, errp);
 113 }
 114
 115 static void file_memory_backend_set_align(Object *o, Visitor *v,
 116                                           const char *name, void *opaque,
 117                                           Error **errp)
 118 {
 119     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 120     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 121     Error *local_err = NULL;
 122     uint64_t val;
 123
 124     if (host_memory_backend_mr_inited(backend)) {
 125         error_setg(&local_err, "cannot change property '%s' of %s",
 126                    name, object_get_typename(o));
 127         goto out;
 128     }
 129
 130     visit_type_size(v, name, &val, &local_err);
 131     if (local_err) {
 132         goto out;
 133     }
 134     fb->align = val;
 135
 136  out:
 137     error_propagate(errp, local_err);
 138 }
 139
 140 static bool file_memory_backend_get_pmem(Object *o, Error **errp)
 141 {
 142     return MEMORY_BACKEND_FILE(o)->is_pmem;
 143 }
 144
 145 static void file_memory_backend_set_pmem(Object *o, bool value, Error **errp)
 146 {
 147     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 148     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 149
 150     if (host_memory_backend_mr_inited(backend)) {
 151
 152         error_setg(errp, "cannot change property 'pmem' of %s.",
 153                    object_get_typename(o));
 154         return;
 155     }
 156
 157 #ifndef CONFIG_LIBPMEM
 158     if (value) {
 159         Error *local_err = NULL;
 160
 161         error_setg(&local_err,
 162                    "Lack of libpmem support while setting the 'pmem=on'"
 163                    " of %s. We can't ensure data persistence.",
 164                    object_get_typename(o));
 165         error_propagate(errp, local_err);
 166         return;
 167     }
 168 #endif
 169
 170     fb->is_pmem = value;
 171 }
 172
 173 static void file_backend_unparent(Object *obj)
 174 {
 175     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
 176     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
 177
 178     if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
 179         void *ptr = memory_region_get_ram_ptr(&backend->mr);
 180         uint64_t sz = memory_region_size(&backend->mr);
 181
 182         qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
 183     }
 184 }
 185
 186 static void
 187 file_backend_class_init(ObjectClass *oc, void *data)
 188 {
 189     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 190
 191     bc->alloc = file_backend_memory_alloc;
 192     oc->unparent = file_backend_unparent;
 193
 194     object_class_property_add_bool(oc, "discard-data",
 195         file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
 196         &error_abort);
 197     object_class_property_add_str(oc, "mem-path",
 198         get_mem_path, set_mem_path,
 199         &error_abort);
 200     object_class_property_add(oc, "align", "int",
 201         file_memory_backend_get_align,
 202         file_memory_backend_set_align,
 203         NULL, NULL, &error_abort);
 204     object_class_property_add_bool(oc, "pmem",
 205         file_memory_backend_get_pmem, file_memory_backend_set_pmem,
 206         &error_abort);
 207 }
 208
 209 static void file_backend_instance_finalize(Object *o)
 210 {
 211     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 212
 213     g_free(fb->mem_path);
 214 }
 215
 216 static const TypeInfo file_backend_info = {
 217     .name = TYPE_MEMORY_BACKEND_FILE,
 218     .parent = TYPE_MEMORY_BACKEND,
 219     .class_init = file_backend_class_init,
 220     .instance_finalize = file_backend_instance_finalize,
 221     .instance_size = sizeof(HostMemoryBackendFile),
 222 };
 223
 224 static void register_types(void)
 225 {
 226     type_register_static(&file_backend_info);
 227 }
 228
 229 type_init(register_types);