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 share;
  35     char *mem_path;
  36 };
  37
  38 static void
  39 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  40 {
  41     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
  42
  43     if (!backend->size) {
  44         error_setg(errp, "can't create backend with size 0");
  45         return;
  46     }
  47     if (!fb->mem_path) {
  48         error_setg(errp, "mem-path property not set");
  49         return;
  50     }
  51 #ifndef CONFIG_LINUX
  52     error_setg(errp, "-mem-path not supported on this host");
  53 #else
  54     if (!memory_region_size(&backend->mr)) {
  55         gchar *path;
  56         backend->force_prealloc = mem_prealloc;
  57         path = object_get_canonical_path(OBJECT(backend));
  58         memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
  59                                  path,
  60                                  backend->size, fb->share,
  61                                  fb->mem_path, errp);
  62         g_free(path);
  63     }
  64 #endif
  65 }
  66
  67 static void
  68 file_backend_class_init(ObjectClass *oc, void *data)
  69 {
  70     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
  71
  72     bc->alloc = file_backend_memory_alloc;
  73 }
  74
  75 static char *get_mem_path(Object *o, Error **errp)
  76 {
  77     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  78
  79     return g_strdup(fb->mem_path);
  80 }
  81
  82 static void set_mem_path(Object *o, const char *str, Error **errp)
  83 {
  84     HostMemoryBackend *backend = MEMORY_BACKEND(o);
  85     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  86
  87     if (memory_region_size(&backend->mr)) {
  88         error_setg(errp, "cannot change property value");
  89         return;
  90     }
  91     g_free(fb->mem_path);
  92     fb->mem_path = g_strdup(str);
  93 }
  94
  95 static bool file_memory_backend_get_share(Object *o, Error **errp)
  96 {
  97     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
  98
  99     return fb->share;
 100 }
 101
 102 static void file_memory_backend_set_share(Object *o, bool value, Error **errp)
 103 {
 104     HostMemoryBackend *backend = MEMORY_BACKEND(o);
 105     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 106
 107     if (memory_region_size(&backend->mr)) {
 108         error_setg(errp, "cannot change property value");
 109         return;
 110     }
 111     fb->share = value;
 112 }
 113
 114 static void
 115 file_backend_instance_init(Object *o)
 116 {
 117     object_property_add_bool(o, "share",
 118                         file_memory_backend_get_share,
 119                         file_memory_backend_set_share, NULL);
 120     object_property_add_str(o, "mem-path", get_mem_path,
 121                             set_mem_path, NULL);
 122 }
 123
 124 static const TypeInfo file_backend_info = {
 125     .name = TYPE_MEMORY_BACKEND_FILE,
 126     .parent = TYPE_MEMORY_BACKEND,
 127     .class_init = file_backend_class_init,
 128     .instance_init = file_backend_instance_init,
 129     .instance_size = sizeof(HostMemoryBackendFile),
 130 };
 131
 132 static void register_types(void)
 133 {
 134     type_register_static(&file_backend_info);
 135 }
 136
 137 type_init(register_types);