ACPI: Add Virtual Machine Generation ID support

This implements the VM Generation ID feature by passing a 128-bit
GUID to the guest via a fw_cfg blob.
Any time the GUID changes, an ACPI notify event is sent to the guest

The user interface is a simple device with one parameter:
 - guid (string, must be "auto" or in UUID format
   xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)

Signed-off-by: Ben Warren <ben@skyportsystems.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

default-configs/i386-softmmu.mak

@@ -59,3 +59,4 @@ CONFIG_I82801B11=y
 CONFIG_SMBIOS=y
 CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
 CONFIG_PXB=y
+CONFIG_ACPI_VMGENID=y

default-configs/x86_64-softmmu.mak

@@ -59,3 +59,4 @@ CONFIG_I82801B11=y
 CONFIG_SMBIOS=y
 CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
 CONFIG_PXB=y
+CONFIG_ACPI_VMGENID=y

hw/acpi/Makefile.objs

@@ -5,6 +5,7 @@ common-obj-$(CONFIG_ACPI_CPU_HOTPLUG) += cpu_hotplug.o
 common-obj-$(CONFIG_ACPI_MEMORY_HOTPLUG) += memory_hotplug.o
 common-obj-$(CONFIG_ACPI_CPU_HOTPLUG) += cpu.o
 common-obj-$(CONFIG_ACPI_NVDIMM) += nvdimm.o
+common-obj-$(CONFIG_ACPI_VMGENID) += vmgenid.o
 common-obj-$(call lnot,$(CONFIG_ACPI_X86)) += acpi-stub.o
 
 common-obj-y += acpi_interface.o

hw/acpi/vmgenid.c

@@ -0,0 +1,242 @@
+/*
+ *  Virtual Machine Generation ID Device
+ *
+ *  Copyright (C) 2017 Skyport Systems.
+ *
+ *  Author: Ben Warren <ben@skyportsystems.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qmp-commands.h"
+#include "hw/acpi/acpi.h"
+#include "hw/acpi/aml-build.h"
+#include "hw/acpi/vmgenid.h"
+#include "hw/nvram/fw_cfg.h"
+#include "sysemu/sysemu.h"
+
+void vmgenid_build_acpi(VmGenIdState *vms, GArray *table_data, GArray *guid,
+                        BIOSLinker *linker)
+{
+    Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx;
+    uint32_t vgia_offset;
+    QemuUUID guid_le;
+
+    /* Fill in the GUID values.  These need to be converted to little-endian
+     * first, since that's what the guest expects
+     */
+    g_array_set_size(guid, VMGENID_FW_CFG_SIZE - ARRAY_SIZE(guid_le.data));
+    guid_le = vms->guid;
+    qemu_uuid_bswap(&guid_le);
+    /* The GUID is written at a fixed offset into the fw_cfg file
+     * in order to implement the "OVMF SDT Header probe suppressor"
+     * see docs/specs/vmgenid.txt for more details
+     */
+    g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data,
+                        ARRAY_SIZE(guid_le.data));
+
+    /* Put this in a separate SSDT table */
+    ssdt = init_aml_allocator();
+
+    /* Reserve space for header */
+    acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
+
+    /* Storage for the GUID address */
+    vgia_offset = table_data->len +
+        build_append_named_dword(ssdt->buf, "VGIA");
+    scope = aml_scope("\\_SB");
+    dev = aml_device("VGEN");
+    aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVGID")));
+    aml_append(dev, aml_name_decl("_CID", aml_string("VM_Gen_Counter")));
+    aml_append(dev, aml_name_decl("_DDN", aml_string("VM_Gen_Counter")));
+
+    /* Simple status method to check that address is linked and non-zero */
+    method = aml_method("_STA", 0, AML_NOTSERIALIZED);
+    addr = aml_local(0);
+    aml_append(method, aml_store(aml_int(0xf), addr));
+    if_ctx = aml_if(aml_equal(aml_name("VGIA"), aml_int(0)));
+    aml_append(if_ctx, aml_store(aml_int(0), addr));
+    aml_append(method, if_ctx);
+    aml_append(method, aml_return(addr));
+    aml_append(dev, method);
+
+    /* the ADDR method returns two 32-bit words representing the lower and
+     * upper halves * of the physical address of the fw_cfg blob
+     * (holding the GUID)
+     */
+    method = aml_method("ADDR", 0, AML_NOTSERIALIZED);
+
+    addr = aml_local(0);
+    aml_append(method, aml_store(aml_package(2), addr));
+
+    aml_append(method, aml_store(aml_add(aml_name("VGIA"),
+                                         aml_int(VMGENID_GUID_OFFSET), NULL),
+                                 aml_index(addr, aml_int(0))));
+    aml_append(method, aml_store(aml_int(0), aml_index(addr, aml_int(1))));
+    aml_append(method, aml_return(addr));
+
+    aml_append(dev, method);
+    aml_append(scope, dev);
+    aml_append(ssdt, scope);
+
+    /* attach an ACPI notify */
+    method = aml_method("\\_GPE._E05", 0, AML_NOTSERIALIZED);
+    aml_append(method, aml_notify(aml_name("\\_SB.VGEN"), aml_int(0x80)));
+    aml_append(ssdt, method);
+
+    g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
+
+    /* Allocate guest memory for the Data fw_cfg blob */
+    bios_linker_loader_alloc(linker, VMGENID_GUID_FW_CFG_FILE, guid, 4096,
+                             false /* page boundary, high memory */);
+
+    /* Patch address of GUID fw_cfg blob into the ADDR fw_cfg blob
+     * so QEMU can write the GUID there.  The address is expected to be
+     * < 4GB, but write 64 bits anyway.
+     * The address that is patched in is offset in order to implement
+     * the "OVMF SDT Header probe suppressor"
+     * see docs/specs/vmgenid.txt for more details.
+     */
+    bios_linker_loader_write_pointer(linker,
+        VMGENID_ADDR_FW_CFG_FILE, 0, sizeof(uint64_t),
+        VMGENID_GUID_FW_CFG_FILE, VMGENID_GUID_OFFSET);
+
+    /* Patch address of GUID fw_cfg blob into the AML so OSPM can retrieve
+     * and read it.  Note that while we provide storage for 64 bits, only
+     * the least-signficant 32 get patched into AML.
+     */
+    bios_linker_loader_add_pointer(linker,
+        ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t),
+        VMGENID_GUID_FW_CFG_FILE, 0);
+
+    build_header(linker, table_data,
+        (void *)(table_data->data + table_data->len - ssdt->buf->len),
+        "SSDT", ssdt->buf->len, 1, NULL, "VMGENID");
+    free_aml_allocator();
+}
+
+void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid)
+{
+    /* Create a read-only fw_cfg file for GUID */
+    fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data,
+                    VMGENID_FW_CFG_SIZE);
+    /* Create a read-write fw_cfg file for Address */
+    fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL,
+                             vms->vmgenid_addr_le,
+                             ARRAY_SIZE(vms->vmgenid_addr_le), false);
+}
+
+static void vmgenid_update_guest(VmGenIdState *vms)
+{
+    Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
+    uint32_t vmgenid_addr;
+    QemuUUID guid_le;
+
+    if (obj) {
+        /* Write the GUID to guest memory */
+        memcpy(&vmgenid_addr, vms->vmgenid_addr_le, sizeof(vmgenid_addr));
+        vmgenid_addr = le32_to_cpu(vmgenid_addr);
+        /* A zero value in vmgenid_addr means that BIOS has not yet written
+         * the address
+         */
+        if (vmgenid_addr) {
+            /* QemuUUID has the first three words as big-endian, and expect
+             * that any GUIDs passed in will always be BE.  The guest,
+             * however, will expect the fields to be little-endian.
+             * Perform a byte swap immediately before writing.
+             */
+            guid_le = vms->guid;
+            qemu_uuid_bswap(&guid_le);
+            /* The GUID is written at a fixed offset into the fw_cfg file
+             * in order to implement the "OVMF SDT Header probe suppressor"
+             * see docs/specs/vmgenid.txt for more details.
+             */
+            cpu_physical_memory_write(vmgenid_addr, guid_le.data,
+                                      sizeof(guid_le.data));
+            /* Send _GPE.E05 event */
+            acpi_send_event(DEVICE(obj), ACPI_VMGENID_CHANGE_STATUS);
+        }
+    }
+}
+
+static void vmgenid_set_guid(Object *obj, const char *value, Error **errp)
+{
+    VmGenIdState *vms = VMGENID(obj);
+
+    if (!strcmp(value, "auto")) {
+        qemu_uuid_generate(&vms->guid);
+    } else if (qemu_uuid_parse(value, &vms->guid) < 0) {
+        error_setg(errp, "'%s. %s': Failed to parse GUID string: %s",
+                   object_get_typename(OBJECT(vms)), VMGENID_GUID, value);
+        return;
+    }
+
+    vmgenid_update_guest(vms);
+}
+
+/* After restoring an image, we need to update the guest memory and notify
+ * it of a potential change to VM Generation ID
+ */
+static int vmgenid_post_load(void *opaque, int version_id)
+{
+    VmGenIdState *vms = opaque;
+    vmgenid_update_guest(vms);
+    return 0;
+}
+
+static const VMStateDescription vmstate_vmgenid = {
+    .name = "vmgenid",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .post_load = vmgenid_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8_ARRAY(vmgenid_addr_le, VmGenIdState, sizeof(uint64_t)),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static void vmgenid_handle_reset(void *opaque)
+{
+    VmGenIdState *vms = VMGENID(opaque);
+    /* Clear the guest-allocated GUID address when the VM resets */
+    memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le));
+}
+
+static void vmgenid_realize(DeviceState *dev, Error **errp)
+{
+    VmGenIdState *vms = VMGENID(dev);
+    qemu_register_reset(vmgenid_handle_reset, vms);
+}
+
+static void vmgenid_device_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->vmsd = &vmstate_vmgenid;
+    dc->realize = vmgenid_realize;
+    dc->hotpluggable = false;
+
+    object_class_property_add_str(klass, VMGENID_GUID, NULL,
+                                  vmgenid_set_guid, NULL);
+    object_class_property_set_description(klass, VMGENID_GUID,
+                                    "Set Global Unique Identifier "
+                                    "(big-endian) or auto for random value",
+                                    NULL);
+}
+
+static const TypeInfo vmgenid_device_info = {
+    .name          = VMGENID_DEVICE,
+    .parent        = TYPE_DEVICE,
+    .instance_size = sizeof(VmGenIdState),
+    .class_init    = vmgenid_device_class_init,
+};
+
+static void vmgenid_register_types(void)
+{
+    type_register_static(&vmgenid_device_info);
+}
+
+type_init(vmgenid_register_types)

hw/i386/acpi-build.c

@@ -42,6 +42,7 @@
 #include "hw/acpi/memory_hotplug.h"
 #include "sysemu/tpm.h"
 #include "hw/acpi/tpm.h"
+#include "hw/acpi/vmgenid.h"
 #include "sysemu/tpm_backend.h"
 #include "hw/timer/mc146818rtc_regs.h"
 #include "sysemu/numa.h"
@@ -2610,6 +2611,7 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
     size_t aml_len = 0;
     GArray *tables_blob = tables->table_data;
     AcpiSlicOem slic_oem = { .id = NULL, .table_id = NULL };
+    Object *vmgenid_dev;
 
     acpi_get_pm_info(&pm);
     acpi_get_misc_info(&misc);
@@ -2653,6 +2655,13 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
     acpi_add_table(table_offsets, tables_blob);
     build_madt(tables_blob, tables->linker, pcms);
 
+    vmgenid_dev = find_vmgenid_dev();
+    if (vmgenid_dev) {
+        acpi_add_table(table_offsets, tables_blob);
+        vmgenid_build_acpi(VMGENID(vmgenid_dev), tables_blob,
+                           tables->vmgenid, tables->linker);
+    }
+
     if (misc.has_hpet) {
         acpi_add_table(table_offsets, tables_blob);
         build_hpet(tables_blob, tables->linker);
@@ -2823,6 +2832,7 @@ void acpi_setup(void)
     PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     AcpiBuildTables tables;
     AcpiBuildState *build_state;
+    Object *vmgenid_dev;
 
     if (!pcms->fw_cfg) {
         ACPI_BUILD_DPRINTF("No fw cfg. Bailing out.\n");
@@ -2859,6 +2869,12 @@ void acpi_setup(void)
     fw_cfg_add_file(pcms->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
                     tables.tcpalog->data, acpi_data_len(tables.tcpalog));
 
+    vmgenid_dev = find_vmgenid_dev();
+    if (vmgenid_dev) {
+        vmgenid_add_fw_cfg(VMGENID(vmgenid_dev), pcms->fw_cfg,
+                           tables.vmgenid);
+    }
+
     if (!pcmc->rsdp_in_ram) {
         /*
          * Keep for compatibility with old machine types.

include/hw/acpi/acpi_dev_interface.h

@@ -11,6 +11,7 @@ typedef enum {
     ACPI_CPU_HOTPLUG_STATUS = 4,
     ACPI_MEMORY_HOTPLUG_STATUS = 8,
     ACPI_NVDIMM_HOTPLUG_STATUS = 16,
+    ACPI_VMGENID_CHANGE_STATUS = 32,
 } AcpiEventStatusBits;
 
 #define TYPE_ACPI_DEVICE_IF "acpi-device-interface"

include/hw/acpi/vmgenid.h

@@ -0,0 +1,35 @@
+#ifndef ACPI_VMGENID_H
+#define ACPI_VMGENID_H
+
+#include "hw/acpi/bios-linker-loader.h"
+#include "hw/qdev.h"
+#include "qemu/uuid.h"
+
+#define VMGENID_DEVICE           "vmgenid"
+#define VMGENID_GUID             "guid"
+#define VMGENID_GUID_FW_CFG_FILE      "etc/vmgenid_guid"
+#define VMGENID_ADDR_FW_CFG_FILE      "etc/vmgenid_addr"
+
+#define VMGENID_FW_CFG_SIZE      4096 /* Occupy a page of memory */
+#define VMGENID_GUID_OFFSET      40   /* allow space for
+                                       * OVMF SDT Header Probe Supressor
+                                       */
+
+#define VMGENID(obj) OBJECT_CHECK(VmGenIdState, (obj), VMGENID_DEVICE)
+
+typedef struct VmGenIdState {
+    DeviceClass parent_obj;
+    QemuUUID guid;                /* The 128-bit GUID seen by the guest */
+    uint8_t vmgenid_addr_le[8];   /* Address of the GUID (little-endian) */
+} VmGenIdState;
+
+static inline Object *find_vmgenid_dev(void)
+{
+    return object_resolve_path_type("", VMGENID_DEVICE, NULL);
+}
+
+void vmgenid_build_acpi(VmGenIdState *vms, GArray *table_data, GArray *guid,
+                        BIOSLinker *linker);
+void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid);
+
+#endif