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