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 "sysemu/hostmem.h"
  13 #include "qom/object_interfaces.h"
  14
  15 /* hostmem-file.c */
  16 /**
  17  * @TYPE_MEMORY_BACKEND_FILE:
  18  * name of backend that uses mmap on a file descriptor
  19  */
  20 #define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
  21
  22 #define MEMORY_BACKEND_FILE(obj) \
  23     OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
  24
  25 typedef struct HostMemoryBackendFile HostMemoryBackendFile;
  26
  27 struct HostMemoryBackendFile {
  28     HostMemoryBackend parent_obj;
  29     char *mem_path;
  30 };
  31
  32 static void
  33 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  34 {
  35     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  36
  37     if (!backend->size) {
  38         error_setg(errp, "can't create backend with size 0");
  39         return;
  40     }
  41     if (!fb->mem_path) {
  42         error_setg(errp, "mem_path property not set");
  43         return;
  44     }
  45 #ifndef CONFIG_LINUX
  46     error_setg(errp, "-mem-path not supported on this host");
  47 #else
  48     if (!memory_region_size(&backend->mr)) {
  49         memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  50                                  object_get_canonical_path(OBJECT(backend)),
  51                                  backend->size,
  52                                  fb->mem_path, errp);
  53     }
  54 #endif
  55 }
  56
  57 static void
  58 file_backend_class_init(ObjectClass *oc, void *data)
  59 {
  60     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
  61
  62     bc->alloc = file_backend_memory_alloc;
  63 }
  64
  65 static char *get_mem_path(Object *o, Error **errp)
  66 {
  67     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  68
  69     return g_strdup(fb->mem_path);
  70 }
  71
  72 static void set_mem_path(Object *o, const char *str, Error **errp)
  73 {
  74     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  75     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  76
  77     if (memory_region_size(&backend->mr)) {
  78         error_setg(errp, "cannot change property value");
  79         return;
  80     }
  81     if (fb->mem_path) {
  82         g_free(fb->mem_path);
  83     }
  84     fb->mem_path = g_strdup(str);
  85 }
  86
  87 static void
  88 file_backend_instance_init(Object *o)
  89 {
  90     object_property_add_str(o, "mem-path", get_mem_path,
  91                             set_mem_path, NULL);
  92 }
  93
  94 static const TypeInfo file_backend_info = {
  95     .name = TYPE_MEMORY_BACKEND_FILE,
  96     .parent = TYPE_MEMORY_BACKEND,
  97     .class_init = file_backend_class_init,
  98     .instance_init = file_backend_instance_init,
  99     .instance_size = sizeof(HostMemoryBackendFile),
 100 };
 101
 102 static void register_types(void)
 103 {
 104     type_register_static(&file_backend_info);
 105 }
 106
 107 type_init(register_types);