hw/acpi/vmgenid.c

   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 = vms->guid;
  34     qemu_uuid_bswap(&guid_le);
  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 = vms->guid;
 153             qemu_uuid_bswap(&guid_le);
 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 = (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", VMGENID_DEVICE);
 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", VMGENID_DEVICE);
 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     dc->props = 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          = VMGENID_DEVICE,
 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
 247 GuidInfo *qmp_query_vm_generation_id(Error **errp)
 248 {
 249     GuidInfo *info;
 250     VmGenIdState *vms;
 251     Object *obj = find_vmgenid_dev();
 252
 253     if (!obj) {
 254         error_setg(errp, "VM Generation ID device not found");
 255         return NULL;
 256     }
 257     vms = VMGENID(obj);
 258
 259     info = g_malloc0(sizeof(*info));
 260     info->guid = qemu_uuid_unparse_strdup(&vms->guid);
 261     return info;
 262 }