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 "qemu/error-report.h"
  16 #include "sysemu/hostmem.h"
  17 #include "sysemu/sysemu.h"
  18 #include "qom/object_interfaces.h"
  19
  20 /* hostmem-file.c */
  21 /**
  22  * @TYPE_MEMORY_BACKEND_FILE:
  23  * name of backend that uses mmap on a file descriptor
  24  */
  25 #define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
  26
  27 #define MEMORY_BACKEND_FILE(obj) \
  28     OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
  29
  30 typedef struct HostMemoryBackendFile HostMemoryBackendFile;
  31
  32 struct HostMemoryBackendFile {
  33     HostMemoryBackend parent_obj;
  34
  35     char *mem_path;
  36     uint64_t align;
  37     bool discard_data;
  38     bool is_pmem;
  39 };
  40
  41 static void
  42 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  43 {
  44 #ifndef CONFIG_POSIX
  45     error_setg(errp, "backend '%s' not supported on this host",
  46                object_get_typename(OBJECT(backend)));
  47 #else
  48     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  49     gchar *name;
  50
  51     if (!backend->size) {
  52         error_setg(errp, "can't create backend with size 0");
  53         return;
  54     }
  55     if (!fb->mem_path) {
  56         error_setg(errp, "mem-path property not set");
  57         return;
  58     }
  59
  60     /*
  61      * Verify pmem file size since starting a guest with an incorrect size
  62      * leads to confusing failures inside the guest.
  63      */
  64     if (fb->is_pmem) {
  65         Error *local_err = NULL;
  66         uint64_t size;
  67
  68         size = qemu_get_pmem_size(fb->mem_path, &local_err);
  69         if (!size) {
  70             error_propagate(errp, local_err);
  71             return;
  72         }
  73
  74         if (backend->size > size) {
  75             error_setg(errp, "size property %" PRIu64 " is larger than "
  76                        "pmem file \"%s\" size %" PRIu64, backend->size,
  77                        fb->mem_path, size);
  78             return;
  79         }
  80     }
  81
  82     backend->force_prealloc = mem_prealloc;
  83     name = host_memory_backend_get_name(backend);
  84     memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  85                                      name,
  86                                      backend->size, fb->align,
  87                                      (backend->share ? RAM_SHARED : 0) |
  88                                      (fb->is_pmem ? RAM_PMEM : 0),
  89                                      fb->mem_path, errp);
  90     g_free(name);
  91 #endif
  92 }
  93
  94 static char *get_mem_path(Object *o, Error **errp)
  95 {
  96     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  97
  98     return g_strdup(fb->mem_path);
  99 }
 100
 101 static void set_mem_path(Object *o, const char *str, Error **errp)
 102 {
 103     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 104     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 105
 106     if (host_memory_backend_mr_inited(backend)) {
 107         error_setg(errp, "cannot change property 'mem-path' of %s",
 108                    object_get_typename(o));
 109         return;
 110     }
 111     g_free(fb->mem_path);
 112     fb->mem_path = g_strdup(str);
 113 }
 114
 115 static bool file_memory_backend_get_discard_data(Object *o, Error **errp)
 116 {
 117     return MEMORY_BACKEND_FILE(o)->discard_data;
 118 }
 119
 120 static void file_memory_backend_set_discard_data(Object *o, bool value,
 121                                                Error **errp)
 122 {
 123     MEMORY_BACKEND_FILE(o)->discard_data = value;
 124 }
 125
 126 static void file_memory_backend_get_align(Object *o, Visitor *v,
 127                                           const char *name, void *opaque,
 128                                           Error **errp)
 129 {
 130     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 131     uint64_t val = fb->align;
 132
 133     visit_type_size(v, name, &val, errp);
 134 }
 135
 136 static void file_memory_backend_set_align(Object *o, Visitor *v,
 137                                           const char *name, void *opaque,
 138                                           Error **errp)
 139 {
 140     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 141     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 142     Error *local_err = NULL;
 143     uint64_t val;
 144
 145     if (host_memory_backend_mr_inited(backend)) {
 146         error_setg(&local_err, "cannot change property '%s' of %s",
 147                    name, object_get_typename(o));
 148         goto out;
 149     }
 150
 151     visit_type_size(v, name, &val, &local_err);
 152     if (local_err) {
 153         goto out;
 154     }
 155     fb->align = val;
 156
 157  out:
 158     error_propagate(errp, local_err);
 159 }
 160
 161 static bool file_memory_backend_get_pmem(Object *o, Error **errp)
 162 {
 163     return MEMORY_BACKEND_FILE(o)->is_pmem;
 164 }
 165
 166 static void file_memory_backend_set_pmem(Object *o, bool value, Error **errp)
 167 {
 168     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 169     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 170
 171     if (host_memory_backend_mr_inited(backend)) {
 172
 173         error_setg(errp, "cannot change property 'pmem' of %s.",
 174                    object_get_typename(o));
 175         return;
 176     }
 177
 178 #ifndef CONFIG_LIBPMEM
 179     if (value) {
 180         Error *local_err = NULL;
 181
 182         error_setg(&local_err,
 183                    "Lack of libpmem support while setting the 'pmem=on'"
 184                    " of %s. We can't ensure data persistence.",
 185                    object_get_typename(o));
 186         error_propagate(errp, local_err);
 187         return;
 188     }
 189 #endif
 190
 191     fb->is_pmem = value;
 192 }
 193
 194 static void file_backend_unparent(Object *obj)
 195 {
 196     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
 197     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
 198
 199     if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
 200         void *ptr = memory_region_get_ram_ptr(&backend->mr);
 201         uint64_t sz = memory_region_size(&backend->mr);
 202
 203         qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
 204     }
 205 }
 206
 207 static void
 208 file_backend_class_init(ObjectClass *oc, void *data)
 209 {
 210     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 211
 212     bc->alloc = file_backend_memory_alloc;
 213     oc->unparent = file_backend_unparent;
 214
 215     object_class_property_add_bool(oc, "discard-data",
 216         file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
 217         &error_abort);
 218     object_class_property_add_str(oc, "mem-path",
 219         get_mem_path, set_mem_path,
 220         &error_abort);
 221     object_class_property_add(oc, "align", "int",
 222         file_memory_backend_get_align,
 223         file_memory_backend_set_align,
 224         NULL, NULL, &error_abort);
 225     object_class_property_add_bool(oc, "pmem",
 226         file_memory_backend_get_pmem, file_memory_backend_set_pmem,
 227         &error_abort);
 228 }
 229
 230 static void file_backend_instance_finalize(Object *o)
 231 {
 232     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 233
 234     g_free(fb->mem_path);
 235 }
 236
 237 static const TypeInfo file_backend_info = {
 238     .name = TYPE_MEMORY_BACKEND_FILE,
 239     .parent = TYPE_MEMORY_BACKEND,
 240     .class_init = file_backend_class_init,
 241     .instance_finalize = file_backend_instance_finalize,
 242     .instance_size = sizeof(HostMemoryBackendFile),
 243 };
 244
 245 static void register_types(void)
 246 {
 247     type_register_static(&file_backend_info);
 248 }
 249
 250 type_init(register_types);