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-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
  33     /* Fill in the GUID values.  These need to be converted to little-endian
  34      * first, since that's what the guest expects
  35      */
  36     g_array_set_size(guid, VMGENID_FW_CFG_SIZE - ARRAY_SIZE(guid_le.data));
  37     guid_le = qemu_uuid_bswap(vms->guid);
  38     /* The GUID is written at a fixed offset into the fw_cfg file
  39      * in order to implement the "OVMF SDT Header probe suppressor"
  40      * see docs/specs/vmgenid.txt for more details
  41      */
  42     g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data,
  43                         ARRAY_SIZE(guid_le.data));
  44
  45     /* Put this in a separate SSDT table */
  46     ssdt = init_aml_allocator();
  47
  48     /* Reserve space for header */
  49     acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
  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     build_header(linker, table_data,
 120         (void *)(table_data->data + table_data->len - ssdt->buf->len),
 121         "SSDT", ssdt->buf->len, 1, oem_id, "VMGENID");
 122     free_aml_allocator();
 123 }
 124
 125 void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid)
 126 {
 127     /* Create a read-only fw_cfg file for GUID */
 128     fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data,
 129                     VMGENID_FW_CFG_SIZE);
 130     /* Create a read-write fw_cfg file for Address */
 131     fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL, NULL,
 132                              vms->vmgenid_addr_le,
 133                              ARRAY_SIZE(vms->vmgenid_addr_le), false);
 134 }
 135
 136 static void vmgenid_update_guest(VmGenIdState *vms)
 137 {
 138     Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
 139     uint32_t vmgenid_addr;
 140     QemuUUID guid_le;
 141
 142     if (obj) {
 143         /* Write the GUID to guest memory */
 144         memcpy(&vmgenid_addr, vms->vmgenid_addr_le, sizeof(vmgenid_addr));
 145         vmgenid_addr = le32_to_cpu(vmgenid_addr);
 146         /* A zero value in vmgenid_addr means that BIOS has not yet written
 147          * the address
 148          */
 149         if (vmgenid_addr) {
 150             /* QemuUUID has the first three words as big-endian, and expect
 151              * that any GUIDs passed in will always be BE.  The guest,
 152              * however, will expect the fields to be little-endian.
 153              * Perform a byte swap immediately before writing.
 154              */
 155             guid_le = qemu_uuid_bswap(vms->guid);
 156             /* The GUID is written at a fixed offset into the fw_cfg file
 157              * in order to implement the "OVMF SDT Header probe suppressor"
 158              * see docs/specs/vmgenid.txt for more details.
 159              */
 160             cpu_physical_memory_write(vmgenid_addr, guid_le.data,
 161                                       sizeof(guid_le.data));
 162             /* Send _GPE.E05 event */
 163             acpi_send_event(DEVICE(obj), ACPI_VMGENID_CHANGE_STATUS);
 164         }
 165     }
 166 }
 167
 168 /* After restoring an image, we need to update the guest memory and notify
 169  * it of a potential change to VM Generation ID
 170  */
 171 static int vmgenid_post_load(void *opaque, int version_id)
 172 {
 173     VmGenIdState *vms = opaque;
 174     vmgenid_update_guest(vms);
 175     return 0;
 176 }
 177
 178 static const VMStateDescription vmstate_vmgenid = {
 179     .name = "vmgenid",
 180     .version_id = 1,
 181     .minimum_version_id = 1,
 182     .post_load = vmgenid_post_load,
 183     .fields = (VMStateField[]) {
 184         VMSTATE_UINT8_ARRAY(vmgenid_addr_le, VmGenIdState, sizeof(uint64_t)),
 185         VMSTATE_END_OF_LIST()
 186     },
 187 };
 188
 189 static void vmgenid_handle_reset(void *opaque)
 190 {
 191     VmGenIdState *vms = VMGENID(opaque);
 192     /* Clear the guest-allocated GUID address when the VM resets */
 193     memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le));
 194 }
 195
 196 static void vmgenid_realize(DeviceState *dev, Error **errp)
 197 {
 198     VmGenIdState *vms = VMGENID(dev);
 199
 200     if (!bios_linker_loader_can_write_pointer()) {
 201         error_setg(errp, "%s requires DMA write support in fw_cfg, "
 202                    "which this machine type does not provide", TYPE_VMGENID);
 203         return;
 204     }
 205
 206     /* Given that this function is executing, there is at least one VMGENID
 207      * device. Check if there are several.
 208      */
 209     if (!find_vmgenid_dev()) {
 210         error_setg(errp, "at most one %s device is permitted", TYPE_VMGENID);
 211         return;
 212     }
 213
 214     qemu_register_reset(vmgenid_handle_reset, vms);
 215
 216     vmgenid_update_guest(vms);
 217 }
 218
 219 static Property vmgenid_device_properties[] = {
 220     DEFINE_PROP_UUID(VMGENID_GUID, VmGenIdState, guid),
 221     DEFINE_PROP_END_OF_LIST(),
 222 };
 223
 224 static void vmgenid_device_class_init(ObjectClass *klass, void *data)
 225 {
 226     DeviceClass *dc = DEVICE_CLASS(klass);
 227
 228     dc->vmsd = &vmstate_vmgenid;
 229     dc->realize = vmgenid_realize;
 230     device_class_set_props(dc, vmgenid_device_properties);
 231     dc->hotpluggable = false;
 232     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 233 }
 234
 235 static const TypeInfo vmgenid_device_info = {
 236     .name          = TYPE_VMGENID,
 237     .parent        = TYPE_DEVICE,
 238     .instance_size = sizeof(VmGenIdState),
 239     .class_init    = vmgenid_device_class_init,
 240 };
 241
 242 static void vmgenid_register_types(void)
 243 {
 244     type_register_static(&vmgenid_device_info);
 245 }
 246
 247 type_init(vmgenid_register_types)
 248
 249 GuidInfo *qmp_query_vm_generation_id(Error **errp)
 250 {
 251     GuidInfo *info;
 252     VmGenIdState *vms;
 253     Object *obj = find_vmgenid_dev();
 254
 255     if (!obj) {
 256         error_setg(errp, "VM Generation ID device not found");
 257         return NULL;
 258     }
 259     vms = VMGENID(obj);
 260
 261     info = g_malloc0(sizeof(*info));
 262     info->guid = qemu_uuid_unparse_strdup(&vms->guid);
 263     return info;
 264 }