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 #include "qom/object.h"
  21
  22 typedef struct HostMemoryBackendFile HostMemoryBackendFile;
  23 DECLARE_INSTANCE_CHECKER(HostMemoryBackendFile, MEMORY_BACKEND_FILE,
  24                          TYPE_MEMORY_BACKEND_FILE)
  25
  26
  27 struct HostMemoryBackendFile {
  28     HostMemoryBackend parent_obj;
  29
  30     char *mem_path;
  31     uint64_t align;
  32     bool discard_data;
  33     bool is_pmem;
  34 };
  35
  36 static void
  37 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  38 {
  39 #ifndef CONFIG_POSIX
  40     error_setg(errp, "backend '%s' not supported on this host",
  41                object_get_typename(OBJECT(backend)));
  42 #else
  43     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  44     gchar *name;
  45
  46     if (!backend->size) {
  47         error_setg(errp, "can't create backend with size 0");
  48         return;
  49     }
  50     if (!fb->mem_path) {
  51         error_setg(errp, "mem-path property not set");
  52         return;
  53     }
  54
  55     name = host_memory_backend_get_name(backend);
  56     memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  57                                      name,
  58                                      backend->size, fb->align,
  59                                      (backend->share ? RAM_SHARED : 0) |
  60                                      (fb->is_pmem ? RAM_PMEM : 0),
  61                                      fb->mem_path, errp);
  62     g_free(name);
  63 #endif
  64 }
  65
  66 static char *get_mem_path(Object *o, Error **errp)
  67 {
  68     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  69
  70     return g_strdup(fb->mem_path);
  71 }
  72
  73 static void set_mem_path(Object *o, const char *str, Error **errp)
  74 {
  75     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  76     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  77
  78     if (host_memory_backend_mr_inited(backend)) {
  79         error_setg(errp, "cannot change property 'mem-path' of %s",
  80                    object_get_typename(o));
  81         return;
  82     }
  83     g_free(fb->mem_path);
  84     fb->mem_path = g_strdup(str);
  85 }
  86
  87 static bool file_memory_backend_get_discard_data(Object *o, Error **errp)
  88 {
  89     return MEMORY_BACKEND_FILE(o)->discard_data;
  90 }
  91
  92 static void file_memory_backend_set_discard_data(Object *o, bool value,
  93                                                Error **errp)
  94 {
  95     MEMORY_BACKEND_FILE(o)->discard_data = value;
  96 }
  97
  98 static void file_memory_backend_get_align(Object *o, Visitor *v,
  99                                           const char *name, void *opaque,
 100                                           Error **errp)
 101 {
 102     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 103     uint64_t val = fb->align;
 104
 105     visit_type_size(v, name, &val, errp);
 106 }
 107
 108 static void file_memory_backend_set_align(Object *o, Visitor *v,
 109                                           const char *name, void *opaque,
 110                                           Error **errp)
 111 {
 112     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 113     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 114     uint64_t val;
 115
 116     if (host_memory_backend_mr_inited(backend)) {
 117         error_setg(errp, "cannot change property '%s' of %s", name,
 118                    object_get_typename(o));
 119         return;
 120     }
 121
 122     if (!visit_type_size(v, name, &val, errp)) {
 123         return;
 124     }
 125     fb->align = val;
 126 }
 127
 128 static bool file_memory_backend_get_pmem(Object *o, Error **errp)
 129 {
 130     return MEMORY_BACKEND_FILE(o)->is_pmem;
 131 }
 132
 133 static void file_memory_backend_set_pmem(Object *o, bool value, Error **errp)
 134 {
 135     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 136     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 137
 138     if (host_memory_backend_mr_inited(backend)) {
 139         error_setg(errp, "cannot change property 'pmem' of %s.",
 140                    object_get_typename(o));
 141         return;
 142     }
 143
 144 #ifndef CONFIG_LIBPMEM
 145     if (value) {
 146         error_setg(errp, "Lack of libpmem support while setting the 'pmem=on'"
 147                    " of %s. We can't ensure data persistence.",
 148                    object_get_typename(o));
 149         return;
 150     }
 151 #endif
 152
 153     fb->is_pmem = value;
 154 }
 155
 156 static void file_backend_unparent(Object *obj)
 157 {
 158     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
 159     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
 160
 161     if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
 162         void *ptr = memory_region_get_ram_ptr(&backend->mr);
 163         uint64_t sz = memory_region_size(&backend->mr);
 164
 165         qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
 166     }
 167 }
 168
 169 static void
 170 file_backend_class_init(ObjectClass *oc, void *data)
 171 {
 172     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 173
 174     bc->alloc = file_backend_memory_alloc;
 175     oc->unparent = file_backend_unparent;
 176
 177     object_class_property_add_bool(oc, "discard-data",
 178         file_memory_backend_get_discard_data, file_memory_backend_set_discard_data);
 179     object_class_property_add_str(oc, "mem-path",
 180         get_mem_path, set_mem_path);
 181     object_class_property_add(oc, "align", "int",
 182         file_memory_backend_get_align,
 183         file_memory_backend_set_align,
 184         NULL, NULL);
 185     object_class_property_add_bool(oc, "pmem",
 186         file_memory_backend_get_pmem, file_memory_backend_set_pmem);
 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);