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