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-common.h"
  13 #include "sysemu/hostmem.h"
  14 #include "sysemu/sysemu.h"
  15 #include "qom/object_interfaces.h"
  16
  17 /* hostmem-file.c */
  18 /**
  19  * @TYPE_MEMORY_BACKEND_FILE:
  20  * name of backend that uses mmap on a file descriptor
  21  */
  22 #define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
  23
  24 #define MEMORY_BACKEND_FILE(obj) \
  25     OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
  26
  27 typedef struct HostMemoryBackendFile HostMemoryBackendFile;
  28
  29 struct HostMemoryBackendFile {
  30     HostMemoryBackend parent_obj;
  31     char *mem_path;
  32 };
  33
  34 static void
  35 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  36 {
  37     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  38
  39     if (!backend->size) {
  40         error_setg(errp, "can't create backend with size 0");
  41         return;
  42     }
  43     if (!fb->mem_path) {
  44         error_setg(errp, "mem_path property not set");
  45         return;
  46     }
  47 #ifndef CONFIG_LINUX
  48     error_setg(errp, "-mem-path not supported on this host");
  49 #else
  50     if (!memory_region_size(&backend->mr)) {
  51         backend->force_prealloc = mem_prealloc;
  52         memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  53                                  object_get_canonical_path(OBJECT(backend)),
  54                                  backend->size,
  55                                  fb->mem_path, errp);
  56     }
  57 #endif
  58 }
  59
  60 static void
  61 file_backend_class_init(ObjectClass *oc, void *data)
  62 {
  63     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
  64
  65     bc->alloc = file_backend_memory_alloc;
  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 (memory_region_size(&backend->mr)) {
  81         error_setg(errp, "cannot change property value");
  82         return;
  83     }
  84     if (fb->mem_path) {
  85         g_free(fb->mem_path);
  86     }
  87     fb->mem_path = g_strdup(str);
  88 }
  89
  90 static void
  91 file_backend_instance_init(Object *o)
  92 {
  93     object_property_add_str(o, "mem-path", get_mem_path,
  94                             set_mem_path, NULL);
  95 }
  96
  97 static const TypeInfo file_backend_info = {
  98     .name = TYPE_MEMORY_BACKEND_FILE,
  99     .parent = TYPE_MEMORY_BACKEND,
 100     .class_init = file_backend_class_init,
 101     .instance_init = file_backend_instance_init,
 102     .instance_size = sizeof(HostMemoryBackendFile),
 103 };
 104
 105 static void register_types(void)
 106 {
 107     type_register_static(&file_backend_info);
 108 }
 109
 110 type_init(register_types);