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 "system/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 #include "migration/cpr.h"
21
22 OBJECT_DECLARE_SIMPLE_TYPE(HostMemoryBackendMemfd, MEMORY_BACKEND_MEMFD)
23
24
25 struct HostMemoryBackendMemfd {
26 HostMemoryBackend parent_obj;
27
28 bool hugetlb;
29 uint64_t hugetlbsize;
30 bool seal;
31 };
32
33 static bool
memfd_backend_memory_alloc(HostMemoryBackend * backend,Error ** errp)34 memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
35 {
36 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
37 g_autofree char *name = host_memory_backend_get_name(backend);
38 int fd = cpr_find_fd(name, 0);
39 uint32_t ram_flags;
40
41 if (!backend->size) {
42 error_setg(errp, "can't create backend with size 0");
43 return false;
44 }
45
46 if (fd >= 0) {
47 goto have_fd;
48 }
49
50 fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
51 m->hugetlb, m->hugetlbsize, m->seal ?
52 F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
53 errp);
54 if (fd == -1) {
55 return false;
56 }
57 cpr_save_fd(name, 0, fd);
58
59 have_fd:
60 backend->aligned = true;
61 ram_flags = backend->share ? RAM_SHARED : RAM_PRIVATE;
62 ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
63 ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
64 return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
65 backend->size, ram_flags, fd, 0, errp);
66 }
67
68 static bool
memfd_backend_get_hugetlb(Object * o,Error ** errp)69 memfd_backend_get_hugetlb(Object *o, Error **errp)
70 {
71 return MEMORY_BACKEND_MEMFD(o)->hugetlb;
72 }
73
74 static void
memfd_backend_set_hugetlb(Object * o,bool value,Error ** errp)75 memfd_backend_set_hugetlb(Object *o, bool value, Error **errp)
76 {
77 MEMORY_BACKEND_MEMFD(o)->hugetlb = value;
78 }
79
80 static void
memfd_backend_set_hugetlbsize(Object * obj,Visitor * v,const char * name,void * opaque,Error ** errp)81 memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name,
82 void *opaque, Error **errp)
83 {
84 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
85 uint64_t value;
86
87 if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) {
88 error_setg(errp, "cannot change property value");
89 return;
90 }
91
92 if (!visit_type_size(v, name, &value, errp)) {
93 return;
94 }
95 if (!value) {
96 error_setg(errp, "Property '%s.%s' doesn't take value '%" PRIu64 "'",
97 object_get_typename(obj), name, value);
98 return;
99 }
100 m->hugetlbsize = value;
101 }
102
103 static void
memfd_backend_get_hugetlbsize(Object * obj,Visitor * v,const char * name,void * opaque,Error ** errp)104 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
105 void *opaque, Error **errp)
106 {
107 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
108 uint64_t value = m->hugetlbsize;
109
110 visit_type_size(v, name, &value, errp);
111 }
112
113 static bool
memfd_backend_get_seal(Object * o,Error ** errp)114 memfd_backend_get_seal(Object *o, Error **errp)
115 {
116 return MEMORY_BACKEND_MEMFD(o)->seal;
117 }
118
119 static void
memfd_backend_set_seal(Object * o,bool value,Error ** errp)120 memfd_backend_set_seal(Object *o, bool value, Error **errp)
121 {
122 MEMORY_BACKEND_MEMFD(o)->seal = value;
123 }
124
125 static void
memfd_backend_instance_init(Object * obj)126 memfd_backend_instance_init(Object *obj)
127 {
128 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
129
130 /* default to sealed file */
131 m->seal = true;
132 MEMORY_BACKEND(m)->share = true;
133 }
134
135 static void
memfd_backend_class_init(ObjectClass * oc,const void * data)136 memfd_backend_class_init(ObjectClass *oc, const void *data)
137 {
138 HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
139
140 bc->alloc = memfd_backend_memory_alloc;
141
142 if (qemu_memfd_check(MFD_HUGETLB)) {
143 object_class_property_add_bool(oc, "hugetlb",
144 memfd_backend_get_hugetlb,
145 memfd_backend_set_hugetlb);
146 object_class_property_set_description(oc, "hugetlb",
147 "Use huge pages");
148 object_class_property_add(oc, "hugetlbsize", "int",
149 memfd_backend_get_hugetlbsize,
150 memfd_backend_set_hugetlbsize,
151 NULL, NULL);
152 object_class_property_set_description(oc, "hugetlbsize",
153 "Huge pages size (ex: 2M, 1G)");
154 }
155 object_class_property_add_bool(oc, "seal",
156 memfd_backend_get_seal,
157 memfd_backend_set_seal);
158 object_class_property_set_description(oc, "seal",
159 "Seal growing & shrinking");
160 }
161
162 static const TypeInfo memfd_backend_info = {
163 .name = TYPE_MEMORY_BACKEND_MEMFD,
164 .parent = TYPE_MEMORY_BACKEND,
165 .instance_init = memfd_backend_instance_init,
166 .class_init = memfd_backend_class_init,
167 .instance_size = sizeof(HostMemoryBackendMemfd),
168 };
169
register_types(void)170 static void register_types(void)
171 {
172 if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
173 type_register_static(&memfd_backend_info);
174 }
175 }
176
177 type_init(register_types);
178