1 /* 2 * Virtual Machine Generation ID Device 3 * 4 * Copyright (C) 2017 Skyport Systems. 5 * 6 * Author: Ben Warren <ben@skyportsystems.com> 7 * 8 * This work is licensed under the terms of the GNU GPL, version 2 or later. 9 * See the COPYING file in the top-level directory. 10 * 11 */ 12 13 #include "qemu/osdep.h" 14 #include "qapi/error.h" 15 #include "qapi/qapi-commands-machine.h" 16 #include "qemu/module.h" 17 #include "hw/acpi/acpi.h" 18 #include "hw/acpi/aml-build.h" 19 #include "hw/acpi/vmgenid.h" 20 #include "hw/nvram/fw_cfg.h" 21 #include "hw/qdev-properties.h" 22 #include "hw/qdev-properties-system.h" 23 #include "migration/vmstate.h" 24 #include "sysemu/reset.h" 25 26 void vmgenid_build_acpi(VmGenIdState *vms, GArray *table_data, GArray *guid, 27 BIOSLinker *linker) 28 { 29 Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx; 30 uint32_t vgia_offset; 31 QemuUUID guid_le; 32 33 /* Fill in the GUID values. These need to be converted to little-endian 34 * first, since that's what the guest expects 35 */ 36 g_array_set_size(guid, VMGENID_FW_CFG_SIZE - ARRAY_SIZE(guid_le.data)); 37 guid_le = qemu_uuid_bswap(vms->guid); 38 /* The GUID is written at a fixed offset into the fw_cfg file 39 * in order to implement the "OVMF SDT Header probe suppressor" 40 * see docs/specs/vmgenid.txt for more details 41 */ 42 g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data, 43 ARRAY_SIZE(guid_le.data)); 44 45 /* Put this in a separate SSDT table */ 46 ssdt = init_aml_allocator(); 47 48 /* Reserve space for header */ 49 acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader)); 50 51 /* Storage for the GUID address */ 52 vgia_offset = table_data->len + 53 build_append_named_dword(ssdt->buf, "VGIA"); 54 scope = aml_scope("\\_SB"); 55 dev = aml_device("VGEN"); 56 aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVGID"))); 57 aml_append(dev, aml_name_decl("_CID", aml_string("VM_Gen_Counter"))); 58 aml_append(dev, aml_name_decl("_DDN", aml_string("VM_Gen_Counter"))); 59 60 /* Simple status method to check that address is linked and non-zero */ 61 method = aml_method("_STA", 0, AML_NOTSERIALIZED); 62 addr = aml_local(0); 63 aml_append(method, aml_store(aml_int(0xf), addr)); 64 if_ctx = aml_if(aml_equal(aml_name("VGIA"), aml_int(0))); 65 aml_append(if_ctx, aml_store(aml_int(0), addr)); 66 aml_append(method, if_ctx); 67 aml_append(method, aml_return(addr)); 68 aml_append(dev, method); 69 70 /* the ADDR method returns two 32-bit words representing the lower and 71 * upper halves * of the physical address of the fw_cfg blob 72 * (holding the GUID) 73 */ 74 method = aml_method("ADDR", 0, AML_NOTSERIALIZED); 75 76 addr = aml_local(0); 77 aml_append(method, aml_store(aml_package(2), addr)); 78 79 aml_append(method, aml_store(aml_add(aml_name("VGIA"), 80 aml_int(VMGENID_GUID_OFFSET), NULL), 81 aml_index(addr, aml_int(0)))); 82 aml_append(method, aml_store(aml_int(0), aml_index(addr, aml_int(1)))); 83 aml_append(method, aml_return(addr)); 84 85 aml_append(dev, method); 86 aml_append(scope, dev); 87 aml_append(ssdt, scope); 88 89 /* attach an ACPI notify */ 90 method = aml_method("\\_GPE._E05", 0, AML_NOTSERIALIZED); 91 aml_append(method, aml_notify(aml_name("\\_SB.VGEN"), aml_int(0x80))); 92 aml_append(ssdt, method); 93 94 g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len); 95 96 /* Allocate guest memory for the Data fw_cfg blob */ 97 bios_linker_loader_alloc(linker, VMGENID_GUID_FW_CFG_FILE, guid, 4096, 98 false /* page boundary, high memory */); 99 100 /* Patch address of GUID fw_cfg blob into the ADDR fw_cfg blob 101 * so QEMU can write the GUID there. The address is expected to be 102 * < 4GB, but write 64 bits anyway. 103 * The address that is patched in is offset in order to implement 104 * the "OVMF SDT Header probe suppressor" 105 * see docs/specs/vmgenid.txt for more details. 106 */ 107 bios_linker_loader_write_pointer(linker, 108 VMGENID_ADDR_FW_CFG_FILE, 0, sizeof(uint64_t), 109 VMGENID_GUID_FW_CFG_FILE, VMGENID_GUID_OFFSET); 110 111 /* Patch address of GUID fw_cfg blob into the AML so OSPM can retrieve 112 * and read it. Note that while we provide storage for 64 bits, only 113 * the least-signficant 32 get patched into AML. 114 */ 115 bios_linker_loader_add_pointer(linker, 116 ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t), 117 VMGENID_GUID_FW_CFG_FILE, 0); 118 119 build_header(linker, table_data, 120 (void *)(table_data->data + table_data->len - ssdt->buf->len), 121 "SSDT", ssdt->buf->len, 1, NULL, "VMGENID"); 122 free_aml_allocator(); 123 } 124 125 void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid) 126 { 127 /* Create a read-only fw_cfg file for GUID */ 128 fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data, 129 VMGENID_FW_CFG_SIZE); 130 /* Create a read-write fw_cfg file for Address */ 131 fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL, NULL, 132 vms->vmgenid_addr_le, 133 ARRAY_SIZE(vms->vmgenid_addr_le), false); 134 } 135 136 static void vmgenid_update_guest(VmGenIdState *vms) 137 { 138 Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL); 139 uint32_t vmgenid_addr; 140 QemuUUID guid_le; 141 142 if (obj) { 143 /* Write the GUID to guest memory */ 144 memcpy(&vmgenid_addr, vms->vmgenid_addr_le, sizeof(vmgenid_addr)); 145 vmgenid_addr = le32_to_cpu(vmgenid_addr); 146 /* A zero value in vmgenid_addr means that BIOS has not yet written 147 * the address 148 */ 149 if (vmgenid_addr) { 150 /* QemuUUID has the first three words as big-endian, and expect 151 * that any GUIDs passed in will always be BE. The guest, 152 * however, will expect the fields to be little-endian. 153 * Perform a byte swap immediately before writing. 154 */ 155 guid_le = qemu_uuid_bswap(vms->guid); 156 /* The GUID is written at a fixed offset into the fw_cfg file 157 * in order to implement the "OVMF SDT Header probe suppressor" 158 * see docs/specs/vmgenid.txt for more details. 159 */ 160 cpu_physical_memory_write(vmgenid_addr, guid_le.data, 161 sizeof(guid_le.data)); 162 /* Send _GPE.E05 event */ 163 acpi_send_event(DEVICE(obj), ACPI_VMGENID_CHANGE_STATUS); 164 } 165 } 166 } 167 168 /* After restoring an image, we need to update the guest memory and notify 169 * it of a potential change to VM Generation ID 170 */ 171 static int vmgenid_post_load(void *opaque, int version_id) 172 { 173 VmGenIdState *vms = opaque; 174 vmgenid_update_guest(vms); 175 return 0; 176 } 177 178 static const VMStateDescription vmstate_vmgenid = { 179 .name = "vmgenid", 180 .version_id = 1, 181 .minimum_version_id = 1, 182 .post_load = vmgenid_post_load, 183 .fields = (VMStateField[]) { 184 VMSTATE_UINT8_ARRAY(vmgenid_addr_le, VmGenIdState, sizeof(uint64_t)), 185 VMSTATE_END_OF_LIST() 186 }, 187 }; 188 189 static void vmgenid_handle_reset(void *opaque) 190 { 191 VmGenIdState *vms = VMGENID(opaque); 192 /* Clear the guest-allocated GUID address when the VM resets */ 193 memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le)); 194 } 195 196 static void vmgenid_realize(DeviceState *dev, Error **errp) 197 { 198 VmGenIdState *vms = VMGENID(dev); 199 200 if (!bios_linker_loader_can_write_pointer()) { 201 error_setg(errp, "%s requires DMA write support in fw_cfg, " 202 "which this machine type does not provide", TYPE_VMGENID); 203 return; 204 } 205 206 /* Given that this function is executing, there is at least one VMGENID 207 * device. Check if there are several. 208 */ 209 if (!find_vmgenid_dev()) { 210 error_setg(errp, "at most one %s device is permitted", TYPE_VMGENID); 211 return; 212 } 213 214 qemu_register_reset(vmgenid_handle_reset, vms); 215 216 vmgenid_update_guest(vms); 217 } 218 219 static Property vmgenid_device_properties[] = { 220 DEFINE_PROP_UUID(VMGENID_GUID, VmGenIdState, guid), 221 DEFINE_PROP_END_OF_LIST(), 222 }; 223 224 static void vmgenid_device_class_init(ObjectClass *klass, void *data) 225 { 226 DeviceClass *dc = DEVICE_CLASS(klass); 227 228 dc->vmsd = &vmstate_vmgenid; 229 dc->realize = vmgenid_realize; 230 device_class_set_props(dc, vmgenid_device_properties); 231 dc->hotpluggable = false; 232 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 233 } 234 235 static const TypeInfo vmgenid_device_info = { 236 .name = TYPE_VMGENID, 237 .parent = TYPE_DEVICE, 238 .instance_size = sizeof(VmGenIdState), 239 .class_init = vmgenid_device_class_init, 240 }; 241 242 static void vmgenid_register_types(void) 243 { 244 type_register_static(&vmgenid_device_info); 245 } 246 247 type_init(vmgenid_register_types) 248 249 GuidInfo *qmp_query_vm_generation_id(Error **errp) 250 { 251 GuidInfo *info; 252 VmGenIdState *vms; 253 Object *obj = find_vmgenid_dev(); 254 255 if (!obj) { 256 error_setg(errp, "VM Generation ID device not found"); 257 return NULL; 258 } 259 vms = VMGENID(obj); 260 261 info = g_malloc0(sizeof(*info)); 262 info->guid = qemu_uuid_unparse_strdup(&vms->guid); 263 return info; 264 } 265