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 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 69 memfd_backend_get_hugetlb(Object *o, Error **errp) 70 { 71 return MEMORY_BACKEND_MEMFD(o)->hugetlb; 72 } 73 74 static void 75 memfd_backend_set_hugetlb(Object *o, bool value, Error **errp) 76 { 77 MEMORY_BACKEND_MEMFD(o)->hugetlb = value; 78 } 79 80 static void 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 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 114 memfd_backend_get_seal(Object *o, Error **errp) 115 { 116 return MEMORY_BACKEND_MEMFD(o)->seal; 117 } 118 119 static void 120 memfd_backend_set_seal(Object *o, bool value, Error **errp) 121 { 122 MEMORY_BACKEND_MEMFD(o)->seal = value; 123 } 124 125 static void 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 136 memfd_backend_class_init(ObjectClass *oc, 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 }; 169 170 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