vmgenid.c (9201B)
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, const char *oem_id) 28 { 29 Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx; 30 uint32_t vgia_offset; 31 QemuUUID guid_le; 32 AcpiTable table = { .sig = "SSDT", .rev = 1, 33 .oem_id = oem_id, .oem_table_id = "VMGENID" }; 34 35 /* Fill in the GUID values. These need to be converted to little-endian 36 * first, since that's what the guest expects 37 */ 38 g_array_set_size(guid, VMGENID_FW_CFG_SIZE - ARRAY_SIZE(guid_le.data)); 39 guid_le = qemu_uuid_bswap(vms->guid); 40 /* The GUID is written at a fixed offset into the fw_cfg file 41 * in order to implement the "OVMF SDT Header probe suppressor" 42 * see docs/specs/vmgenid.txt for more details 43 */ 44 g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data, 45 ARRAY_SIZE(guid_le.data)); 46 47 /* Put VMGNEID into a separate SSDT table */ 48 acpi_table_begin(&table, table_data); 49 ssdt = init_aml_allocator(); 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 /* must be called after above command to ensure correct table checksum */ 120 acpi_table_end(linker, &table); 121 free_aml_allocator(); 122 } 123 124 void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid) 125 { 126 /* Create a read-only fw_cfg file for GUID */ 127 fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data, 128 VMGENID_FW_CFG_SIZE); 129 /* Create a read-write fw_cfg file for Address */ 130 fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL, NULL, 131 vms->vmgenid_addr_le, 132 ARRAY_SIZE(vms->vmgenid_addr_le), false); 133 } 134 135 static void vmgenid_update_guest(VmGenIdState *vms) 136 { 137 Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL); 138 uint32_t vmgenid_addr; 139 QemuUUID guid_le; 140 141 if (obj) { 142 /* Write the GUID to guest memory */ 143 memcpy(&vmgenid_addr, vms->vmgenid_addr_le, sizeof(vmgenid_addr)); 144 vmgenid_addr = le32_to_cpu(vmgenid_addr); 145 /* A zero value in vmgenid_addr means that BIOS has not yet written 146 * the address 147 */ 148 if (vmgenid_addr) { 149 /* QemuUUID has the first three words as big-endian, and expect 150 * that any GUIDs passed in will always be BE. The guest, 151 * however, will expect the fields to be little-endian. 152 * Perform a byte swap immediately before writing. 153 */ 154 guid_le = qemu_uuid_bswap(vms->guid); 155 /* The GUID is written at a fixed offset into the fw_cfg file 156 * in order to implement the "OVMF SDT Header probe suppressor" 157 * see docs/specs/vmgenid.txt for more details. 158 */ 159 cpu_physical_memory_write(vmgenid_addr, guid_le.data, 160 sizeof(guid_le.data)); 161 /* Send _GPE.E05 event */ 162 acpi_send_event(DEVICE(obj), ACPI_VMGENID_CHANGE_STATUS); 163 } 164 } 165 } 166 167 /* After restoring an image, we need to update the guest memory and notify 168 * it of a potential change to VM Generation ID 169 */ 170 static int vmgenid_post_load(void *opaque, int version_id) 171 { 172 VmGenIdState *vms = opaque; 173 vmgenid_update_guest(vms); 174 return 0; 175 } 176 177 static const VMStateDescription vmstate_vmgenid = { 178 .name = "vmgenid", 179 .version_id = 1, 180 .minimum_version_id = 1, 181 .post_load = vmgenid_post_load, 182 .fields = (VMStateField[]) { 183 VMSTATE_UINT8_ARRAY(vmgenid_addr_le, VmGenIdState, sizeof(uint64_t)), 184 VMSTATE_END_OF_LIST() 185 }, 186 }; 187 188 static void vmgenid_handle_reset(void *opaque) 189 { 190 VmGenIdState *vms = VMGENID(opaque); 191 /* Clear the guest-allocated GUID address when the VM resets */ 192 memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le)); 193 } 194 195 static void vmgenid_realize(DeviceState *dev, Error **errp) 196 { 197 VmGenIdState *vms = VMGENID(dev); 198 199 if (!bios_linker_loader_can_write_pointer()) { 200 error_setg(errp, "%s requires DMA write support in fw_cfg, " 201 "which this machine type does not provide", TYPE_VMGENID); 202 return; 203 } 204 205 /* Given that this function is executing, there is at least one VMGENID 206 * device. Check if there are several. 207 */ 208 if (!find_vmgenid_dev()) { 209 error_setg(errp, "at most one %s device is permitted", TYPE_VMGENID); 210 return; 211 } 212 213 qemu_register_reset(vmgenid_handle_reset, vms); 214 215 vmgenid_update_guest(vms); 216 } 217 218 static Property vmgenid_device_properties[] = { 219 DEFINE_PROP_UUID(VMGENID_GUID, VmGenIdState, guid), 220 DEFINE_PROP_END_OF_LIST(), 221 }; 222 223 static void vmgenid_device_class_init(ObjectClass *klass, void *data) 224 { 225 DeviceClass *dc = DEVICE_CLASS(klass); 226 227 dc->vmsd = &vmstate_vmgenid; 228 dc->realize = vmgenid_realize; 229 device_class_set_props(dc, vmgenid_device_properties); 230 dc->hotpluggable = false; 231 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 232 } 233 234 static const TypeInfo vmgenid_device_info = { 235 .name = TYPE_VMGENID, 236 .parent = TYPE_DEVICE, 237 .instance_size = sizeof(VmGenIdState), 238 .class_init = vmgenid_device_class_init, 239 }; 240 241 static void vmgenid_register_types(void) 242 { 243 type_register_static(&vmgenid_device_info); 244 } 245 246 type_init(vmgenid_register_types) 247 248 GuidInfo *qmp_query_vm_generation_id(Error **errp) 249 { 250 GuidInfo *info; 251 VmGenIdState *vms; 252 Object *obj = find_vmgenid_dev(); 253 254 if (!obj) { 255 error_setg(errp, "VM Generation ID device not found"); 256 return NULL; 257 } 258 vms = VMGENID(obj); 259 260 info = g_malloc0(sizeof(*info)); 261 info->guid = qemu_uuid_unparse_strdup(&vms->guid); 262 return info; 263 }