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 #ifdef CONFIG_POSIX
  46     gchar *name;
  47 #endif
  48
  49     if (!backend->size) {
  50         error_setg(errp, "can't create backend with size 0");
  51         return;
  52     }
  53     if (!fb->mem_path) {
  54         error_setg(errp, "mem-path property not set");
  55         return;
  56     }
  57 #ifndef CONFIG_POSIX
  58     error_setg(errp, "-mem-path not supported on this host");
  59 #else
  60     backend->force_prealloc = mem_prealloc;
  61     name = host_memory_backend_get_name(backend);
  62     memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  63                                      name,
  64                                      backend->size, fb->align,
  65                                      (backend->share ? RAM_SHARED : 0) |
  66                                      (fb->is_pmem ? RAM_PMEM : 0),
  67                                      fb->mem_path, errp);
  68     g_free(name);
  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
 149         error_setg(errp, "cannot change property 'pmem' of %s.",
 150                    object_get_typename(o));
 151         return;
 152     }
 153
 154 #ifndef CONFIG_LIBPMEM
 155     if (value) {
 156         Error *local_err = NULL;
 157
 158         error_setg(&local_err,
 159                    "Lack of libpmem support while setting the 'pmem=on'"
 160                    " of %s. We can't ensure data persistence.",
 161                    object_get_typename(o));
 162         error_propagate(errp, local_err);
 163         return;
 164     }
 165 #endif
 166
 167     fb->is_pmem = value;
 168 }
 169
 170 static void file_backend_unparent(Object *obj)
 171 {
 172     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
 173     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
 174
 175     if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
 176         void *ptr = memory_region_get_ram_ptr(&backend->mr);
 177         uint64_t sz = memory_region_size(&backend->mr);
 178
 179         qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
 180     }
 181 }
 182
 183 static void
 184 file_backend_class_init(ObjectClass *oc, void *data)
 185 {
 186     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 187
 188     bc->alloc = file_backend_memory_alloc;
 189     oc->unparent = file_backend_unparent;
 190
 191     object_class_property_add_bool(oc, "discard-data",
 192         file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
 193         &error_abort);
 194     object_class_property_add_str(oc, "mem-path",
 195         get_mem_path, set_mem_path,
 196         &error_abort);
 197     object_class_property_add(oc, "align", "int",
 198         file_memory_backend_get_align,
 199         file_memory_backend_set_align,
 200         NULL, NULL, &error_abort);
 201     object_class_property_add_bool(oc, "pmem",
 202         file_memory_backend_get_pmem, file_memory_backend_set_pmem,
 203         &error_abort);
 204 }
 205
 206 static void file_backend_instance_finalize(Object *o)
 207 {
 208     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 209
 210     g_free(fb->mem_path);
 211 }
 212
 213 static const TypeInfo file_backend_info = {
 214     .name = TYPE_MEMORY_BACKEND_FILE,
 215     .parent = TYPE_MEMORY_BACKEND,
 216     .class_init = file_backend_class_init,
 217     .instance_finalize = file_backend_instance_finalize,
 218     .instance_size = sizeof(HostMemoryBackendFile),
 219 };
 220
 221 static void register_types(void)
 222 {
 223     type_register_static(&file_backend_info);
 224 }
 225
 226 type_init(register_types);