From: Ben Warren <ben@skyportsystems.com>

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>
---
 default-configs/i386-softmmu.mak     |   1 +
 default-configs/x86_64-softmmu.mak   |   1 +
 hw/acpi/Makefile.objs                |   1 +
 hw/acpi/vmgenid.c                    | 239 +++++++++++++++++++++++++++++++++++
 hw/i386/acpi-build.c                 |  16 +++
 include/hw/acpi/acpi_dev_interface.h |   1 +
 include/hw/acpi/vmgenid.h            |  35 +++++
 7 files changed, 294 insertions(+)
 create mode 100644 hw/acpi/vmgenid.c
 create mode 100644 include/hw/acpi/vmgenid.h

diff --git a/default-configs/i386-softmmu.mak b/default-configs/i386-softmmu.mak
index 48b07a4..029e952 100644
--- a/default-configs/i386-softmmu.mak
+++ b/default-configs/i386-softmmu.mak
@@ -59,3 +59,4 @@ CONFIG_I82801B11=y
 CONFIG_SMBIOS=y
 CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
 CONFIG_PXB=y
+CONFIG_ACPI_VMGENID=y
diff --git a/default-configs/x86_64-softmmu.mak b/default-configs/x86_64-softmmu.mak
index fd96345..d1d7432 100644
--- a/default-configs/x86_64-softmmu.mak
+++ b/default-configs/x86_64-softmmu.mak
@@ -59,3 +59,4 @@ CONFIG_I82801B11=y
 CONFIG_SMBIOS=y
 CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
 CONFIG_PXB=y
+CONFIG_ACPI_VMGENID=y
diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
index 6acf798..11c35bc 100644
--- a/hw/acpi/Makefile.objs
+++ b/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
diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
new file mode 100644
index 0000000..8fba7e0
--- /dev/null
+++ b/hw/acpi/vmgenid.c
@@ -0,0 +1,239 @@
+/*
+ *  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.
+     */
+    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)
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 1c928ab..db04cf5 100644
--- a/hw/i386/acpi-build.c
+++ b/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.
diff --git a/include/hw/acpi/acpi_dev_interface.h b/include/hw/acpi/acpi_dev_interface.h
index 71d3c48..3c2e4e9 100644
--- a/include/hw/acpi/acpi_dev_interface.h
+++ b/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"
diff --git a/include/hw/acpi/vmgenid.h b/include/hw/acpi/vmgenid.h
new file mode 100644
index 0000000..db7fa0e
--- /dev/null
+++ b/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
-- 
2.7.4

On Wed, 15 Feb 2017 22:18:14 -0800
ben@skyportsystems.com wrote:

> From: Ben Warren <ben@skyportsystems.com>
> 
> 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>

Thing to get fixed on top is to check
that there isn't vmgenid device present already
into realizefn() and fail gracefully is there is.

> ---
>  default-configs/i386-softmmu.mak     |   1 +
>  default-configs/x86_64-softmmu.mak   |   1 +
>  hw/acpi/Makefile.objs                |   1 +
>  hw/acpi/vmgenid.c                    | 239 +++++++++++++++++++++++++++++++++++
>  hw/i386/acpi-build.c                 |  16 +++
>  include/hw/acpi/acpi_dev_interface.h |   1 +
>  include/hw/acpi/vmgenid.h            |  35 +++++
>  7 files changed, 294 insertions(+)
>  create mode 100644 hw/acpi/vmgenid.c
>  create mode 100644 include/hw/acpi/vmgenid.h
> 
> diff --git a/default-configs/i386-softmmu.mak b/default-configs/i386-softmmu.mak
> index 48b07a4..029e952 100644
> --- a/default-configs/i386-softmmu.mak
> +++ b/default-configs/i386-softmmu.mak
> @@ -59,3 +59,4 @@ CONFIG_I82801B11=y
>  CONFIG_SMBIOS=y
>  CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
>  CONFIG_PXB=y
> +CONFIG_ACPI_VMGENID=y
> diff --git a/default-configs/x86_64-softmmu.mak b/default-configs/x86_64-softmmu.mak
> index fd96345..d1d7432 100644
> --- a/default-configs/x86_64-softmmu.mak
> +++ b/default-configs/x86_64-softmmu.mak
> @@ -59,3 +59,4 @@ CONFIG_I82801B11=y
>  CONFIG_SMBIOS=y
>  CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
>  CONFIG_PXB=y
> +CONFIG_ACPI_VMGENID=y
> diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
> index 6acf798..11c35bc 100644
> --- a/hw/acpi/Makefile.objs
> +++ b/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
> diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
> new file mode 100644
> index 0000000..8fba7e0
> --- /dev/null
> +++ b/hw/acpi/vmgenid.c
> @@ -0,0 +1,239 @@
> +/*
> + *  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.
> +     */
> +    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)
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 1c928ab..db04cf5 100644
> --- a/hw/i386/acpi-build.c
> +++ b/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.
> diff --git a/include/hw/acpi/acpi_dev_interface.h b/include/hw/acpi/acpi_dev_interface.h
> index 71d3c48..3c2e4e9 100644
> --- a/include/hw/acpi/acpi_dev_interface.h
> +++ b/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"
> diff --git a/include/hw/acpi/vmgenid.h b/include/hw/acpi/vmgenid.h
> new file mode 100644
> index 0000000..db7fa0e
> --- /dev/null
> +++ b/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

> On Feb 16, 2017, at 1:56 AM, Igor Mammedov <imammedo@redhat.com> wrote:
> 
> On Wed, 15 Feb 2017 22:18:14 -0800
> ben@skyportsystems.com wrote:
> 
>> From: Ben Warren <ben@skyportsystems.com>
>> 
>> 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>
> 
> Thing to get fixed on top is to check
> that there isn't vmgenid device present already
> into realizefn() and fail gracefully is there is.
> 
I made the change as follows:
===

diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
index c8465df..fa3de6d 100644
--- a/hw/acpi/vmgenid.c
+++ b/hw/acpi/vmgenid.c
@@ -207,8 +207,15 @@ static void vmgenid_handle_reset(void *opaque)
 
 static void vmgenid_realize(DeviceState *dev, Error **errp)
 {
+    static bool is_realized = false;
     VmGenIdState *vms = VMGENID(dev);
+
+    if (is_realized) {
+        error_setg(errp, "Device %s may only be specified once",
+                   VMGENID_DEVICE);
+    }
     qemu_register_reset(vmgenid_handle_reset, vms);
+    is_realized = true;
 }

===
Sample output:
$ ../workspace/qemu/x86_64-softmmu/qemu-system-x86_64 -nographic -bios ../workspace/seabios/out/bios.bin -machine type=q35 -hda beiwe-with-vmgenid-driver.qcow2 -qmp unix:./qmp-sock,server,nowait -device vmgenid,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb66" -device vmgenid,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb67"
qemu-system-x86_64: -device vmgenid,guid=324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb67: Device vmgenid may only be specified once


Good enough?  If so, I’ll roll it in.  Otherwise, it’ll be a supplemental patch.

—Ben

<snip>

On 02/16/17 19:32, Ben Warren wrote:
> 
>> On Feb 16, 2017, at 1:56 AM, Igor Mammedov <imammedo@redhat.com> wrote:
>>
>> On Wed, 15 Feb 2017 22:18:14 -0800
>> ben@skyportsystems.com wrote:
>>
>>> From: Ben Warren <ben@skyportsystems.com>
>>>
>>> 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>
>>
>> Thing to get fixed on top is to check
>> that there isn't vmgenid device present already
>> into realizefn() and fail gracefully is there is.
>>
> I made the change as follows:
> ===
> 
> diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
> index c8465df..fa3de6d 100644
> --- a/hw/acpi/vmgenid.c
> +++ b/hw/acpi/vmgenid.c
> @@ -207,8 +207,15 @@ static void vmgenid_handle_reset(void *opaque)
>  
>  static void vmgenid_realize(DeviceState *dev, Error **errp)
>  {
> +    static bool is_realized = false;
>      VmGenIdState *vms = VMGENID(dev);
> +
> +    if (is_realized) {
> +        error_setg(errp, "Device %s may only be specified once",
> +                   VMGENID_DEVICE);
> +    }
>      qemu_register_reset(vmgenid_handle_reset, vms);
> +    is_realized = true;
>  }
> 
> ===
> Sample output:
> $ ../workspace/qemu/x86_64-softmmu/qemu-system-x86_64 -nographic -bios ../workspace/seabios/out/bios.bin -machine type=q35 -hda beiwe-with-vmgenid-driver.qcow2 -qmp unix:./qmp-sock,server,nowait -device vmgenid,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb66" -device vmgenid,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb67"
> qemu-system-x86_64: -device vmgenid,guid=324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb67: Device vmgenid may only be specified once
> 
> 
> Good enough?  If so, I’ll roll it in.  Otherwise, it’ll be a supplemental patch.

Ehm, I'd say let's postpone that patch. Function (or even file) scope
static variables that plaster over QOM shortcomings (or, well,
"non-trivial QOM patterns") are strongly frowned upon. I've done it
myself before (totally as a last resort, really -- not kidding!), and it
was real hard to get into the tree.

This deserves more discussion, so please delay it.

(While at it, please remember my other recommendation for realize():
enforcing that the running machine type / version provides the guest
with the DMA interface for fw_cfg. For that, based on prior consensus,
you'll need another device property, to be set in parallel to
fw_cfg_mem's and fw_cfg_io's "dma-enabled" property. So I think it makes
sense to address all of these things in a separate, followup series.)

Thanks!
Laszlo

> On Feb 16, 2017, at 11:03 AM, Laszlo Ersek <lersek@redhat.com> wrote:
> 
> On 02/16/17 19:32, Ben Warren wrote:
>> 
>>> On Feb 16, 2017, at 1:56 AM, Igor Mammedov <imammedo@redhat.com> wrote:
>>> 
>>> On Wed, 15 Feb 2017 22:18:14 -0800
>>> ben@skyportsystems.com wrote:
>>> 
>>>> From: Ben Warren <ben@skyportsystems.com>
>>>> 
>>>> 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>
>>> 
>>> Thing to get fixed on top is to check
>>> that there isn't vmgenid device present already
>>> into realizefn() and fail gracefully is there is.
>>> 
>> I made the change as follows:
>> ===
>> 
>> diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
>> index c8465df..fa3de6d 100644
>> --- a/hw/acpi/vmgenid.c
>> +++ b/hw/acpi/vmgenid.c
>> @@ -207,8 +207,15 @@ static void vmgenid_handle_reset(void *opaque)
>> 
>> static void vmgenid_realize(DeviceState *dev, Error **errp)
>> {
>> +    static bool is_realized = false;
>>     VmGenIdState *vms = VMGENID(dev);
>> +
>> +    if (is_realized) {
>> +        error_setg(errp, "Device %s may only be specified once",
>> +                   VMGENID_DEVICE);
>> +    }
>>     qemu_register_reset(vmgenid_handle_reset, vms);
>> +    is_realized = true;
>> }
>> 
>> ===
>> Sample output:
>> $ ../workspace/qemu/x86_64-softmmu/qemu-system-x86_64 -nographic -bios ../workspace/seabios/out/bios.bin -machine type=q35 -hda beiwe-with-vmgenid-driver.qcow2 -qmp unix:./qmp-sock,server,nowait -device vmgenid,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb66" -device vmgenid,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb67"
>> qemu-system-x86_64: -device vmgenid,guid=324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb67: Device vmgenid may only be specified once
>> 
>> 
>> Good enough?  If so, I’ll roll it in.  Otherwise, it’ll be a supplemental patch.
> 
> Ehm, I'd say let's postpone that patch. Function (or even file) scope
> static variables that plaster over QOM shortcomings (or, well,
> "non-trivial QOM patterns") are strongly frowned upon. I've done it
> myself before (totally as a last resort, really -- not kidding!), and it
> was real hard to get into the tree.
> 
> This deserves more discussion, so please delay it.
> 
> (While at it, please remember my other recommendation for realize():
> enforcing that the running machine type / version provides the guest
> with the DMA interface for fw_cfg. For that, based on prior consensus,
> you'll need another device property, to be set in parallel to
> fw_cfg_mem's and fw_cfg_io's "dma-enabled" property. So I think it makes
> sense to address all of these things in a separate, followup series.)
> 
OK, makes sense.
> Thanks!
> Laszlo

—Ben

On 02/16/17 07:18, ben@skyportsystems.com wrote:
> From: Ben Warren <ben@skyportsystems.com>
> 
> 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>
> ---
>  default-configs/i386-softmmu.mak     |   1 +
>  default-configs/x86_64-softmmu.mak   |   1 +
>  hw/acpi/Makefile.objs                |   1 +
>  hw/acpi/vmgenid.c                    | 239 +++++++++++++++++++++++++++++++++++
>  hw/i386/acpi-build.c                 |  16 +++
>  include/hw/acpi/acpi_dev_interface.h |   1 +
>  include/hw/acpi/vmgenid.h            |  35 +++++
>  7 files changed, 294 insertions(+)
>  create mode 100644 hw/acpi/vmgenid.c
>  create mode 100644 include/hw/acpi/vmgenid.h

I compared this version against v6. It looks good. I also tested it
(with the fixup I mentioned under v7 1/8, and without live migration).

Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>

Thanks
Laszlo