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