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