hostmem: allow preallocation of any memory region
[qemu.git] / 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);