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 "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 = (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)