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 "qemu-common.h"
  14 #include "sysemu/hostmem.h"
  15 #include "sysemu/sysemu.h"
  16 #include "qom/object_interfaces.h"
  17
  18 /* hostmem-file.c */
  19 /**
  20  * @TYPE_MEMORY_BACKEND_FILE:
  21  * name of backend that uses mmap on a file descriptor
  22  */
  23 #define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
  24
  25 #define MEMORY_BACKEND_FILE(obj) \
  26     OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
  27
  28 typedef struct HostMemoryBackendFile HostMemoryBackendFile;
  29
  30 struct HostMemoryBackendFile {
  31     HostMemoryBackend parent_obj;
  32
  33     bool share;
  34     char *mem_path;
  35 };
  36
  37 static void
  38 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  39 {
  40     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  41
  42     if (!backend->size) {
  43         error_setg(errp, "can't create backend with size 0");
  44         return;
  45     }
  46     if (!fb->mem_path) {
  47         error_setg(errp, "mem-path property not set");
  48         return;
  49     }
  50 #ifndef CONFIG_LINUX
  51     error_setg(errp, "-mem-path not supported on this host");
  52 #else
  53     if (!memory_region_size(&backend->mr)) {
  54         backend->force_prealloc = mem_prealloc;
  55         memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  56                                  object_get_canonical_path(OBJECT(backend)),
  57                                  backend->size, fb->share,
  58                                  fb->mem_path, errp);
  59     }
  60 #endif
  61 }
  62
  63 static void
  64 file_backend_class_init(ObjectClass *oc, void *data)
  65 {
  66     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
  67
  68     bc->alloc = file_backend_memory_alloc;
  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 (memory_region_size(&backend->mr)) {
  84         error_setg(errp, "cannot change property value");
  85         return;
  86     }
  87     g_free(fb->mem_path);
  88     fb->mem_path = g_strdup(str);
  89 }
  90
  91 static bool file_memory_backend_get_share(Object *o, Error **errp)
  92 {
  93     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  94
  95     return fb->share;
  96 }
  97
  98 static void file_memory_backend_set_share(Object *o, bool value, Error **errp)
  99 {
 100     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 101     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 102
 103     if (memory_region_size(&backend->mr)) {
 104         error_setg(errp, "cannot change property value");
 105         return;
 106     }
 107     fb->share = value;
 108 }
 109
 110 static void
 111 file_backend_instance_init(Object *o)
 112 {
 113     object_property_add_bool(o, "share",
 114                         file_memory_backend_get_share,
 115                         file_memory_backend_set_share, NULL);
 116     object_property_add_str(o, "mem-path", get_mem_path,
 117                             set_mem_path, NULL);
 118 }
 119
 120 static const TypeInfo file_backend_info = {
 121     .name = TYPE_MEMORY_BACKEND_FILE,
 122     .parent = TYPE_MEMORY_BACKEND,
 123     .class_init = file_backend_class_init,
 124     .instance_init = file_backend_instance_init,
 125     .instance_size = sizeof(HostMemoryBackendFile),
 126 };
 127
 128 static void register_types(void)
 129 {
 130     type_register_static(&file_backend_info);
 131 }
 132
 133 type_init(register_types);