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