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 = qemu_uuid_bswap(vms->guid);
  34     /* The GUID is written at a fixed offset into the fw_cfg file
  35      * in order to implement the "OVMF SDT Header probe suppressor"
  36      * see docs/specs/vmgenid.txt for more details
  37      */
  38     g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data,
  39                         ARRAY_SIZE(guid_le.data));
  40
  41     /* Put this in a separate SSDT table */
  42     ssdt = init_aml_allocator();
  43
  44     /* Reserve space for header */
  45     acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
  46
  47     /* Storage for the GUID address */
  48     vgia_offset = table_data->len +
  49         build_append_named_dword(ssdt->buf, "VGIA");
  50     scope = aml_scope("\\_SB");
  51     dev = aml_device("VGEN");
  52     aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVGID")));
  53     aml_append(dev, aml_name_decl("_CID", aml_string("VM_Gen_Counter")));
  54     aml_append(dev, aml_name_decl("_DDN", aml_string("VM_Gen_Counter")));
  55
  56     /* Simple status method to check that address is linked and non-zero */
  57     method = aml_method("_STA", 0, AML_NOTSERIALIZED);
  58     addr = aml_local(0);
  59     aml_append(method, aml_store(aml_int(0xf), addr));
  60     if_ctx = aml_if(aml_equal(aml_name("VGIA"), aml_int(0)));
  61     aml_append(if_ctx, aml_store(aml_int(0), addr));
  62     aml_append(method, if_ctx);
  63     aml_append(method, aml_return(addr));
  64     aml_append(dev, method);
  65
  66     /* the ADDR method returns two 32-bit words representing the lower and
  67      * upper halves * of the physical address of the fw_cfg blob
  68      * (holding the GUID)
  69      */
  70     method = aml_method("ADDR", 0, AML_NOTSERIALIZED);
  71
  72     addr = aml_local(0);
  73     aml_append(method, aml_store(aml_package(2), addr));
  74
  75     aml_append(method, aml_store(aml_add(aml_name("VGIA"),
  76                                          aml_int(VMGENID_GUID_OFFSET), NULL),
  77                                  aml_index(addr, aml_int(0))));
  78     aml_append(method, aml_store(aml_int(0), aml_index(addr, aml_int(1))));
  79     aml_append(method, aml_return(addr));
  80
  81     aml_append(dev, method);
  82     aml_append(scope, dev);
  83     aml_append(ssdt, scope);
  84
  85     /* attach an ACPI notify */
  86     method = aml_method("\\_GPE._E05", 0, AML_NOTSERIALIZED);
  87     aml_append(method, aml_notify(aml_name("\\_SB.VGEN"), aml_int(0x80)));
  88     aml_append(ssdt, method);
  89
  90     g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
  91
  92     /* Allocate guest memory for the Data fw_cfg blob */
  93     bios_linker_loader_alloc(linker, VMGENID_GUID_FW_CFG_FILE, guid, 4096,
  94                              false /* page boundary, high memory */);
  95
  96     /* Patch address of GUID fw_cfg blob into the ADDR fw_cfg blob
  97      * so QEMU can write the GUID there.  The address is expected to be
  98      * < 4GB, but write 64 bits anyway.
  99      * The address that is patched in is offset in order to implement
 100      * the "OVMF SDT Header probe suppressor"
 101      * see docs/specs/vmgenid.txt for more details.
 102      */
 103     bios_linker_loader_write_pointer(linker,
 104         VMGENID_ADDR_FW_CFG_FILE, 0, sizeof(uint64_t),
 105         VMGENID_GUID_FW_CFG_FILE, VMGENID_GUID_OFFSET);
 106
 107     /* Patch address of GUID fw_cfg blob into the AML so OSPM can retrieve
 108      * and read it.  Note that while we provide storage for 64 bits, only
 109      * the least-signficant 32 get patched into AML.
 110      */
 111     bios_linker_loader_add_pointer(linker,
 112         ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t),
 113         VMGENID_GUID_FW_CFG_FILE, 0);
 114
 115     build_header(linker, table_data,
 116         (void *)(table_data->data + table_data->len - ssdt->buf->len),
 117         "SSDT", ssdt->buf->len, 1, NULL, "VMGENID");
 118     free_aml_allocator();
 119 }
 120
 121 void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid)
 122 {
 123     /* Create a read-only fw_cfg file for GUID */
 124     fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data,
 125                     VMGENID_FW_CFG_SIZE);
 126     /* Create a read-write fw_cfg file for Address */
 127     fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL, NULL,
 128                              vms->vmgenid_addr_le,
 129                              ARRAY_SIZE(vms->vmgenid_addr_le), false);
 130 }
 131
 132 static void vmgenid_update_guest(VmGenIdState *vms)
 133 {
 134     Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
 135     uint32_t vmgenid_addr;
 136     QemuUUID guid_le;
 137
 138     if (obj) {
 139         /* Write the GUID to guest memory */
 140         memcpy(&vmgenid_addr, vms->vmgenid_addr_le, sizeof(vmgenid_addr));
 141         vmgenid_addr = le32_to_cpu(vmgenid_addr);
 142         /* A zero value in vmgenid_addr means that BIOS has not yet written
 143          * the address
 144          */
 145         if (vmgenid_addr) {
 146             /* QemuUUID has the first three words as big-endian, and expect
 147              * that any GUIDs passed in will always be BE.  The guest,
 148              * however, will expect the fields to be little-endian.
 149              * Perform a byte swap immediately before writing.
 150              */
 151             guid_le = qemu_uuid_bswap(vms->guid);
 152             /* The GUID is written at a fixed offset into the fw_cfg file
 153              * in order to implement the "OVMF SDT Header probe suppressor"
 154              * see docs/specs/vmgenid.txt for more details.
 155              */
 156             cpu_physical_memory_write(vmgenid_addr, guid_le.data,
 157                                       sizeof(guid_le.data));
 158             /* Send _GPE.E05 event */
 159             acpi_send_event(DEVICE(obj), ACPI_VMGENID_CHANGE_STATUS);
 160         }
 161     }
 162 }
 163
 164 /* After restoring an image, we need to update the guest memory and notify
 165  * it of a potential change to VM Generation ID
 166  */
 167 static int vmgenid_post_load(void *opaque, int version_id)
 168 {
 169     VmGenIdState *vms = opaque;
 170     vmgenid_update_guest(vms);
 171     return 0;
 172 }
 173
 174 static const VMStateDescription vmstate_vmgenid = {
 175     .name = "vmgenid",
 176     .version_id = 1,
 177     .minimum_version_id = 1,
 178     .post_load = vmgenid_post_load,
 179     .fields = (VMStateField[]) {
 180         VMSTATE_UINT8_ARRAY(vmgenid_addr_le, VmGenIdState, sizeof(uint64_t)),
 181         VMSTATE_END_OF_LIST()
 182     },
 183 };
 184
 185 static void vmgenid_handle_reset(void *opaque)
 186 {
 187     VmGenIdState *vms = VMGENID(opaque);
 188     /* Clear the guest-allocated GUID address when the VM resets */
 189     memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le));
 190 }
 191
 192 static void vmgenid_realize(DeviceState *dev, Error **errp)
 193 {
 194     VmGenIdState *vms = VMGENID(dev);
 195
 196     if (!bios_linker_loader_can_write_pointer()) {
 197         error_setg(errp, "%s requires DMA write support in fw_cfg, "
 198                    "which this machine type does not provide", VMGENID_DEVICE);
 199         return;
 200     }
 201
 202     /* Given that this function is executing, there is at least one VMGENID
 203      * device. Check if there are several.
 204      */
 205     if (!find_vmgenid_dev()) {
 206         error_setg(errp, "at most one %s device is permitted", VMGENID_DEVICE);
 207         return;
 208     }
 209
 210     qemu_register_reset(vmgenid_handle_reset, vms);
 211
 212     vmgenid_update_guest(vms);
 213 }
 214
 215 static Property vmgenid_device_properties[] = {
 216     DEFINE_PROP_UUID(VMGENID_GUID, VmGenIdState, guid),
 217     DEFINE_PROP_END_OF_LIST(),
 218 };
 219
 220 static void vmgenid_device_class_init(ObjectClass *klass, void *data)
 221 {
 222     DeviceClass *dc = DEVICE_CLASS(klass);
 223
 224     dc->vmsd = &vmstate_vmgenid;
 225     dc->realize = vmgenid_realize;
 226     dc->props = vmgenid_device_properties;
 227     dc->hotpluggable = false;
 228     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 229 }
 230
 231 static const TypeInfo vmgenid_device_info = {
 232     .name          = VMGENID_DEVICE,
 233     .parent        = TYPE_DEVICE,
 234     .instance_size = sizeof(VmGenIdState),
 235     .class_init    = vmgenid_device_class_init,
 236 };
 237
 238 static void vmgenid_register_types(void)
 239 {
 240     type_register_static(&vmgenid_device_info);
 241 }
 242
 243 type_init(vmgenid_register_types)
 244
 245 GuidInfo *qmp_query_vm_generation_id(Error **errp)
 246 {
 247     GuidInfo *info;
 248     VmGenIdState *vms;
 249     Object *obj = find_vmgenid_dev();
 250
 251     if (!obj) {
 252         error_setg(errp, "VM Generation ID device not found");
 253         return NULL;
 254     }
 255     vms = VMGENID(obj);
 256
 257     info = g_malloc0(sizeof(*info));
 258     info->guid = qemu_uuid_unparse_strdup(&vms->guid);
 259     return info;
 260 }