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 "sysemu/hostmem.h"
  16 #include "sysemu/sysemu.h"
  17 #include "qom/object_interfaces.h"
  18
  19 /* hostmem-file.c */
  20 /**
  21  * @TYPE_MEMORY_BACKEND_FILE:
  22  * name of backend that uses mmap on a file descriptor
  23  */
  24 #define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
  25
  26 #define MEMORY_BACKEND_FILE(obj) \
  27     OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
  28
  29 typedef struct HostMemoryBackendFile HostMemoryBackendFile;
  30
  31 struct HostMemoryBackendFile {
  32     HostMemoryBackend parent_obj;
  33
  34     bool share;
  35     bool discard_data;
  36     char *mem_path;
  37 };
  38
  39 static void
  40 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  41 {
  42     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  43
  44     if (!backend->size) {
  45         error_setg(errp, "can't create backend with size 0");
  46         return;
  47     }
  48     if (!fb->mem_path) {
  49         error_setg(errp, "mem-path property not set");
  50         return;
  51     }
  52 #ifndef CONFIG_LINUX
  53     error_setg(errp, "-mem-path not supported on this host");
  54 #else
  55     if (!host_memory_backend_mr_inited(backend)) {
  56         gchar *path;
  57         backend->force_prealloc = mem_prealloc;
  58         path = object_get_canonical_path(OBJECT(backend));
  59         memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  60                                  path,
  61                                  backend->size, fb->share,
  62                                  fb->mem_path, errp);
  63         g_free(path);
  64     }
  65 #endif
  66 }
  67
  68 static char *get_mem_path(Object *o, Error **errp)
  69 {
  70     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  71
  72     return g_strdup(fb->mem_path);
  73 }
  74
  75 static void set_mem_path(Object *o, const char *str, Error **errp)
  76 {
  77     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  78     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  79
  80     if (host_memory_backend_mr_inited(backend)) {
  81         error_setg(errp, "cannot change property value");
  82         return;
  83     }
  84     g_free(fb->mem_path);
  85     fb->mem_path = g_strdup(str);
  86 }
  87
  88 static bool file_memory_backend_get_share(Object *o, Error **errp)
  89 {
  90     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  91
  92     return fb->share;
  93 }
  94
  95 static void file_memory_backend_set_share(Object *o, bool value, Error **errp)
  96 {
  97     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  98     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  99
 100     if (host_memory_backend_mr_inited(backend)) {
 101         error_setg(errp, "cannot change property value");
 102         return;
 103     }
 104     fb->share = value;
 105 }
 106
 107 static bool file_memory_backend_get_discard_data(Object *o, Error **errp)
 108 {
 109     return MEMORY_BACKEND_FILE(o)->discard_data;
 110 }
 111
 112 static void file_memory_backend_set_discard_data(Object *o, bool value,
 113                                                Error **errp)
 114 {
 115     MEMORY_BACKEND_FILE(o)->discard_data = value;
 116 }
 117
 118 static void file_backend_unparent(Object *obj)
 119 {
 120     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
 121     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
 122
 123     if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
 124         void *ptr = memory_region_get_ram_ptr(&backend->mr);
 125         uint64_t sz = memory_region_size(&backend->mr);
 126
 127         qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
 128     }
 129 }
 130
 131 static void
 132 file_backend_class_init(ObjectClass *oc, void *data)
 133 {
 134     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 135
 136     bc->alloc = file_backend_memory_alloc;
 137     oc->unparent = file_backend_unparent;
 138
 139     object_class_property_add_bool(oc, "share",
 140         file_memory_backend_get_share, file_memory_backend_set_share,
 141         &error_abort);
 142     object_class_property_add_bool(oc, "discard-data",
 143         file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
 144         &error_abort);
 145     object_class_property_add_str(oc, "mem-path",
 146         get_mem_path, set_mem_path,
 147         &error_abort);
 148 }
 149
 150 static void file_backend_instance_finalize(Object *o)
 151 {
 152     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 153
 154     g_free(fb->mem_path);
 155 }
 156
 157 static const TypeInfo file_backend_info = {
 158     .name = TYPE_MEMORY_BACKEND_FILE,
 159     .parent = TYPE_MEMORY_BACKEND,
 160     .class_init = file_backend_class_init,
 161     .instance_finalize = file_backend_instance_finalize,
 162     .instance_size = sizeof(HostMemoryBackendFile),
 163 };
 164
 165 static void register_types(void)
 166 {
 167     type_register_static(&file_backend_info);
 168 }
 169
 170 type_init(register_types);