1 /*
2 * QEMU host memfd memory backend
3 *
4 * Copyright (C) 2018 Red Hat Inc
5 *
6 * Authors:
7 * Marc-André Lureau <marcandre.lureau@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
13 #include "qemu/osdep.h"
14 #include "sysemu/hostmem.h"
15 #include "qom/object_interfaces.h"
16 #include "qemu/memfd.h"
17 #include "qemu/module.h"
18 #include "qapi/error.h"
19 #include "qom/object.h"
20
21 #define TYPE_MEMORY_BACKEND_MEMFD "memory-backend-memfd"
22
23 OBJECT_DECLARE_SIMPLE_TYPE(HostMemoryBackendMemfd, MEMORY_BACKEND_MEMFD)
24
25
26 struct HostMemoryBackendMemfd {
27 HostMemoryBackend parent_obj;
28
29 bool hugetlb;
30 uint64_t hugetlbsize;
31 bool seal;
32 };
33
34 static bool
memfd_backend_memory_alloc(HostMemoryBackend * backend,Error ** errp)35 memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
36 {
37 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
38 g_autofree char *name = NULL;
39 uint32_t ram_flags;
40 int fd;
41
42 if (!backend->size) {
43 error_setg(errp, "can't create backend with size 0");
44 return false;
45 }
46
47 fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
48 m->hugetlb, m->hugetlbsize, m->seal ?
49 F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
50 errp);
51 if (fd == -1) {
52 return false;
53 }
54
55 backend->aligned = true;
56 name = host_memory_backend_get_name(backend);
57 ram_flags = backend->share ? RAM_SHARED : 0;
58 ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
59 ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
60 return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
61 backend->size, ram_flags, fd, 0, errp);
62 }
63
64 static bool
memfd_backend_get_hugetlb(Object * o,Error ** errp)65 memfd_backend_get_hugetlb(Object *o, Error **errp)
66 {
67 return MEMORY_BACKEND_MEMFD(o)->hugetlb;
68 }
69
70 static void
memfd_backend_set_hugetlb(Object * o,bool value,Error ** errp)71 memfd_backend_set_hugetlb(Object *o, bool value, Error **errp)
72 {
73 MEMORY_BACKEND_MEMFD(o)->hugetlb = value;
74 }
75
76 static void
memfd_backend_set_hugetlbsize(Object * obj,Visitor * v,const char * name,void * opaque,Error ** errp)77 memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name,
78 void *opaque, Error **errp)
79 {
80 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
81 uint64_t value;
82
83 if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) {
84 error_setg(errp, "cannot change property value");
85 return;
86 }
87
88 if (!visit_type_size(v, name, &value, errp)) {
89 return;
90 }
91 if (!value) {
92 error_setg(errp, "Property '%s.%s' doesn't take value '%" PRIu64 "'",
93 object_get_typename(obj), name, value);
94 return;
95 }
96 m->hugetlbsize = value;
97 }
98
99 static void
memfd_backend_get_hugetlbsize(Object * obj,Visitor * v,const char * name,void * opaque,Error ** errp)100 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
101 void *opaque, Error **errp)
102 {
103 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
104 uint64_t value = m->hugetlbsize;
105
106 visit_type_size(v, name, &value, errp);
107 }
108
109 static bool
memfd_backend_get_seal(Object * o,Error ** errp)110 memfd_backend_get_seal(Object *o, Error **errp)
111 {
112 return MEMORY_BACKEND_MEMFD(o)->seal;
113 }
114
115 static void
memfd_backend_set_seal(Object * o,bool value,Error ** errp)116 memfd_backend_set_seal(Object *o, bool value, Error **errp)
117 {
118 MEMORY_BACKEND_MEMFD(o)->seal = value;
119 }
120
121 static void
memfd_backend_instance_init(Object * obj)122 memfd_backend_instance_init(Object *obj)
123 {
124 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
125
126 /* default to sealed file */
127 m->seal = true;
128 MEMORY_BACKEND(m)->share = true;
129 }
130
131 static void
memfd_backend_class_init(ObjectClass * oc,void * data)132 memfd_backend_class_init(ObjectClass *oc, void *data)
133 {
134 HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
135
136 bc->alloc = memfd_backend_memory_alloc;
137
138 if (qemu_memfd_check(MFD_HUGETLB)) {
139 object_class_property_add_bool(oc, "hugetlb",
140 memfd_backend_get_hugetlb,
141 memfd_backend_set_hugetlb);
142 object_class_property_set_description(oc, "hugetlb",
143 "Use huge pages");
144 object_class_property_add(oc, "hugetlbsize", "int",
145 memfd_backend_get_hugetlbsize,
146 memfd_backend_set_hugetlbsize,
147 NULL, NULL);
148 object_class_property_set_description(oc, "hugetlbsize",
149 "Huge pages size (ex: 2M, 1G)");
150 }
151 object_class_property_add_bool(oc, "seal",
152 memfd_backend_get_seal,
153 memfd_backend_set_seal);
154 object_class_property_set_description(oc, "seal",
155 "Seal growing & shrinking");
156 }
157
158 static const TypeInfo memfd_backend_info = {
159 .name = TYPE_MEMORY_BACKEND_MEMFD,
160 .parent = TYPE_MEMORY_BACKEND,
161 .instance_init = memfd_backend_instance_init,
162 .class_init = memfd_backend_class_init,
163 .instance_size = sizeof(HostMemoryBackendMemfd),
164 };
165
register_types(void)166 static void register_types(void)
167 {
168 if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
169 type_register_static(&memfd_backend_info);
170 }
171 }
172
173 type_init(register_types);
174