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
  32     bool share;
  33     char *mem_path;
  34 };
  35
  36 static void
  37 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  38 {
  39     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  40
  41     if (!backend->size) {
  42         error_setg(errp, "can't create backend with size 0");
  43         return;
  44     }
  45     if (!fb->mem_path) {
  46         error_setg(errp, "mem-path property not set");
  47         return;
  48     }
  49 #ifndef CONFIG_LINUX
  50     error_setg(errp, "-mem-path not supported on this host");
  51 #else
  52     if (!memory_region_size(&backend->mr)) {
  53         backend->force_prealloc = mem_prealloc;
  54         memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  55                                  object_get_canonical_path(OBJECT(backend)),
  56                                  backend->size, fb->share,
  57                                  fb->mem_path, errp);
  58     }
  59 #endif
  60 }
  61
  62 static void
  63 file_backend_class_init(ObjectClass *oc, void *data)
  64 {
  65     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
  66
  67     bc->alloc = file_backend_memory_alloc;
  68 }
  69
  70 static char *get_mem_path(Object *o, Error **errp)
  71 {
  72     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  73
  74     return g_strdup(fb->mem_path);
  75 }
  76
  77 static void set_mem_path(Object *o, const char *str, Error **errp)
  78 {
  79     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  80     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  81
  82     if (memory_region_size(&backend->mr)) {
  83         error_setg(errp, "cannot change property value");
  84         return;
  85     }
  86     if (fb->mem_path) {
  87         g_free(fb->mem_path);
  88     }
  89     fb->mem_path = g_strdup(str);
  90 }
  91
  92 static bool file_memory_backend_get_share(Object *o, Error **errp)
  93 {
  94     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  95
  96     return fb->share;
  97 }
  98
  99 static void file_memory_backend_set_share(Object *o, bool value, Error **errp)
 100 {
 101     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 102     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 103
 104     if (memory_region_size(&backend->mr)) {
 105         error_setg(errp, "cannot change property value");
 106         return;
 107     }
 108     fb->share = value;
 109 }
 110
 111 static void
 112 file_backend_instance_init(Object *o)
 113 {
 114     object_property_add_bool(o, "share",
 115                         file_memory_backend_get_share,
 116                         file_memory_backend_set_share, NULL);
 117     object_property_add_str(o, "mem-path", get_mem_path,
 118                             set_mem_path, NULL);
 119 }
 120
 121 static const TypeInfo file_backend_info = {
 122     .name = TYPE_MEMORY_BACKEND_FILE,
 123     .parent = TYPE_MEMORY_BACKEND,
 124     .class_init = file_backend_class_init,
 125     .instance_init = file_backend_instance_init,
 126     .instance_size = sizeof(HostMemoryBackendFile),
 127 };
 128
 129 static void register_types(void)
 130 {
 131     type_register_static(&file_backend_info);
 132 }
 133
 134 type_init(register_types);