hostmem-memfd.c (4904B)
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 void 35 memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) 36 { 37 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend); 38 uint32_t ram_flags; 39 char *name; 40 int fd; 41 42 if (!backend->size) { 43 error_setg(errp, "can't create backend with size 0"); 44 return; 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; 53 } 54 55 name = host_memory_backend_get_name(backend); 56 ram_flags = backend->share ? RAM_SHARED : 0; 57 ram_flags |= backend->reserve ? 0 : RAM_NORESERVE; 58 memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name, 59 backend->size, ram_flags, fd, 0, errp); 60 g_free(name); 61 } 62 63 static bool 64 memfd_backend_get_hugetlb(Object *o, Error **errp) 65 { 66 return MEMORY_BACKEND_MEMFD(o)->hugetlb; 67 } 68 69 static void 70 memfd_backend_set_hugetlb(Object *o, bool value, Error **errp) 71 { 72 MEMORY_BACKEND_MEMFD(o)->hugetlb = value; 73 } 74 75 static void 76 memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name, 77 void *opaque, Error **errp) 78 { 79 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj); 80 uint64_t value; 81 82 if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) { 83 error_setg(errp, "cannot change property value"); 84 return; 85 } 86 87 if (!visit_type_size(v, name, &value, errp)) { 88 return; 89 } 90 if (!value) { 91 error_setg(errp, "Property '%s.%s' doesn't take value '%" PRIu64 "'", 92 object_get_typename(obj), name, value); 93 return; 94 } 95 m->hugetlbsize = value; 96 } 97 98 static void 99 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name, 100 void *opaque, Error **errp) 101 { 102 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj); 103 uint64_t value = m->hugetlbsize; 104 105 visit_type_size(v, name, &value, errp); 106 } 107 108 static bool 109 memfd_backend_get_seal(Object *o, Error **errp) 110 { 111 return MEMORY_BACKEND_MEMFD(o)->seal; 112 } 113 114 static void 115 memfd_backend_set_seal(Object *o, bool value, Error **errp) 116 { 117 MEMORY_BACKEND_MEMFD(o)->seal = value; 118 } 119 120 static void 121 memfd_backend_instance_init(Object *obj) 122 { 123 HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj); 124 125 /* default to sealed file */ 126 m->seal = true; 127 MEMORY_BACKEND(m)->share = true; 128 } 129 130 static void 131 memfd_backend_class_init(ObjectClass *oc, void *data) 132 { 133 HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc); 134 135 bc->alloc = memfd_backend_memory_alloc; 136 137 if (qemu_memfd_check(MFD_HUGETLB)) { 138 object_class_property_add_bool(oc, "hugetlb", 139 memfd_backend_get_hugetlb, 140 memfd_backend_set_hugetlb); 141 object_class_property_set_description(oc, "hugetlb", 142 "Use huge pages"); 143 object_class_property_add(oc, "hugetlbsize", "int", 144 memfd_backend_get_hugetlbsize, 145 memfd_backend_set_hugetlbsize, 146 NULL, NULL); 147 object_class_property_set_description(oc, "hugetlbsize", 148 "Huge pages size (ex: 2M, 1G)"); 149 } 150 object_class_property_add_bool(oc, "seal", 151 memfd_backend_get_seal, 152 memfd_backend_set_seal); 153 object_class_property_set_description(oc, "seal", 154 "Seal growing & shrinking"); 155 } 156 157 static const TypeInfo memfd_backend_info = { 158 .name = TYPE_MEMORY_BACKEND_MEMFD, 159 .parent = TYPE_MEMORY_BACKEND, 160 .instance_init = memfd_backend_instance_init, 161 .class_init = memfd_backend_class_init, 162 .instance_size = sizeof(HostMemoryBackendMemfd), 163 }; 164 165 static void register_types(void) 166 { 167 if (qemu_memfd_check(MFD_ALLOW_SEALING)) { 168 type_register_static(&memfd_backend_info); 169 } 170 } 171 172 type_init(register_types);