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