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 discard_data;
  35     char *mem_path;
  36     uint64_t align;
  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->align, backend->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_discard_data(Object *o, Error **errp)
  89 {
  90     return MEMORY_BACKEND_FILE(o)->discard_data;
  91 }
  92
  93 static void file_memory_backend_set_discard_data(Object *o, bool value,
  94                                                Error **errp)
  95 {
  96     MEMORY_BACKEND_FILE(o)->discard_data = value;
  97 }
  98
  99 static void file_memory_backend_get_align(Object *o, Visitor *v,
 100                                           const char *name, void *opaque,
 101                                           Error **errp)
 102 {
 103     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 104     uint64_t val = fb->align;
 105
 106     visit_type_size(v, name, &val, errp);
 107 }
 108
 109 static void file_memory_backend_set_align(Object *o, Visitor *v,
 110                                           const char *name, void *opaque,
 111                                           Error **errp)
 112 {
 113     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 114     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 115     Error *local_err = NULL;
 116     uint64_t val;
 117
 118     if (host_memory_backend_mr_inited(backend)) {
 119         error_setg(&local_err, "cannot change property value");
 120         goto out;
 121     }
 122
 123     visit_type_size(v, name, &val, &local_err);
 124     if (local_err) {
 125         goto out;
 126     }
 127     fb->align = val;
 128
 129  out:
 130     error_propagate(errp, local_err);
 131 }
 132
 133 static void file_backend_unparent(Object *obj)
 134 {
 135     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
 136     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
 137
 138     if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
 139         void *ptr = memory_region_get_ram_ptr(&backend->mr);
 140         uint64_t sz = memory_region_size(&backend->mr);
 141
 142         qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
 143     }
 144 }
 145
 146 static void
 147 file_backend_class_init(ObjectClass *oc, void *data)
 148 {
 149     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 150
 151     bc->alloc = file_backend_memory_alloc;
 152     oc->unparent = file_backend_unparent;
 153
 154     object_class_property_add_bool(oc, "discard-data",
 155         file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
 156         &error_abort);
 157     object_class_property_add_str(oc, "mem-path",
 158         get_mem_path, set_mem_path,
 159         &error_abort);
 160     object_class_property_add(oc, "align", "int",
 161         file_memory_backend_get_align,
 162         file_memory_backend_set_align,
 163         NULL, NULL, &error_abort);
 164 }
 165
 166 static void file_backend_instance_finalize(Object *o)
 167 {
 168     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 169
 170     g_free(fb->mem_path);
 171 }
 172
 173 static const TypeInfo file_backend_info = {
 174     .name = TYPE_MEMORY_BACKEND_FILE,
 175     .parent = TYPE_MEMORY_BACKEND,
 176     .class_init = file_backend_class_init,
 177     .instance_finalize = file_backend_instance_finalize,
 178     .instance_size = sizeof(HostMemoryBackendFile),
 179 };
 180
 181 static void register_types(void)
 182 {
 183     type_register_static(&file_backend_info);
 184 }
 185
 186 type_init(register_types);