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     backend->force_prealloc = mem_prealloc;
  60     name = host_memory_backend_get_name(backend);
  61     memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  62                                      name,
  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(name);
  68 #endif
  69 }
  70
  71 static char *get_mem_path(Object *o, Error **errp)
  72 {
  73     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  74
  75     return g_strdup(fb->mem_path);
  76 }
  77
  78 static void set_mem_path(Object *o, const char *str, Error **errp)
  79 {
  80     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  81     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  82
  83     if (host_memory_backend_mr_inited(backend)) {
  84         error_setg(errp, "cannot change property 'mem-path' of %s",
  85                    object_get_typename(o));
  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 '%s' of %s",
 124                    name, object_get_typename(o));
 125         goto out;
 126     }
 127
 128     visit_type_size(v, name, &val, &local_err);
 129     if (local_err) {
 130         goto out;
 131     }
 132     fb->align = val;
 133
 134  out:
 135     error_propagate(errp, local_err);
 136 }
 137
 138 static bool file_memory_backend_get_pmem(Object *o, Error **errp)
 139 {
 140     return MEMORY_BACKEND_FILE(o)->is_pmem;
 141 }
 142
 143 static void file_memory_backend_set_pmem(Object *o, bool value, Error **errp)
 144 {
 145     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 146     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 147
 148     if (host_memory_backend_mr_inited(backend)) {
 149
 150         error_setg(errp, "cannot change property 'pmem' of %s.",
 151                    object_get_typename(o));
 152         return;
 153     }
 154
 155 #ifndef CONFIG_LIBPMEM
 156     if (value) {
 157         Error *local_err = NULL;
 158
 159         error_setg(&local_err,
 160                    "Lack of libpmem support while setting the 'pmem=on'"
 161                    " of %s. We can't ensure data persistence.",
 162                    object_get_typename(o));
 163         error_propagate(errp, local_err);
 164         return;
 165     }
 166 #endif
 167
 168     fb->is_pmem = value;
 169 }
 170
 171 static void file_backend_unparent(Object *obj)
 172 {
 173     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
 174     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
 175
 176     if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
 177         void *ptr = memory_region_get_ram_ptr(&backend->mr);
 178         uint64_t sz = memory_region_size(&backend->mr);
 179
 180         qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
 181     }
 182 }
 183
 184 static void
 185 file_backend_class_init(ObjectClass *oc, void *data)
 186 {
 187     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 188
 189     bc->alloc = file_backend_memory_alloc;
 190     oc->unparent = file_backend_unparent;
 191
 192     object_class_property_add_bool(oc, "discard-data",
 193         file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
 194         &error_abort);
 195     object_class_property_add_str(oc, "mem-path",
 196         get_mem_path, set_mem_path,
 197         &error_abort);
 198     object_class_property_add(oc, "align", "int",
 199         file_memory_backend_get_align,
 200         file_memory_backend_set_align,
 201         NULL, NULL, &error_abort);
 202     object_class_property_add_bool(oc, "pmem",
 203         file_memory_backend_get_pmem, file_memory_backend_set_pmem,
 204         &error_abort);
 205 }
 206
 207 static void file_backend_instance_finalize(Object *o)
 208 {
 209     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 210
 211     g_free(fb->mem_path);
 212 }
 213
 214 static const TypeInfo file_backend_info = {
 215     .name = TYPE_MEMORY_BACKEND_FILE,
 216     .parent = TYPE_MEMORY_BACKEND,
 217     .class_init = file_backend_class_init,
 218     .instance_finalize = file_backend_instance_finalize,
 219     .instance_size = sizeof(HostMemoryBackendFile),
 220 };
 221
 222 static void register_types(void)
 223 {
 224     type_register_static(&file_backend_info);
 225 }
 226
 227 type_init(register_types);