Re: [Qemu-devel] [PATCH v5 05/10] ACPI: Add Virtual Machine Generation ID support

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Feb 05, 2017 at 01:12:00AM -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>


Thanks!
I think it's mostly in a good shape.
Comments inside.


> ---
>  default-configs/i386-softmmu.mak     |   1 +
>  default-configs/x86_64-softmmu.mak   |   1 +
>  hw/acpi/Makefile.objs                |   1 +
>  hw/acpi/vmgenid.c                    | 206 +++++++++++++++++++++++++++++++++++
>  hw/i386/acpi-build.c                 |  10 ++
>  include/hw/acpi/acpi_dev_interface.h |   1 +
>  include/hw/acpi/vmgenid.h            |  37 +++++++
>  7 files changed, 257 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 384cefb..1a43542 100644
> --- a/default-configs/i386-softmmu.mak
> +++ b/default-configs/i386-softmmu.mak
> @@ -58,3 +58,4 @@ CONFIG_I82801B11=y
>  CONFIG_SMBIOS=y
>  CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
>  CONFIG_PXB=y
> +CONFIG_ACPI_VMGENID=y
> diff --git a/default-configs/x86_64-softmmu.mak b/default-configs/x86_64-softmmu.mak
> index 491a191..aee8b08 100644
> --- a/default-configs/x86_64-softmmu.mak
> +++ b/default-configs/x86_64-softmmu.mak
> @@ -58,3 +58,4 @@ CONFIG_I82801B11=y
>  CONFIG_SMBIOS=y
>  CONFIG_HYPERV_TESTDEV=$(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..6c9ecfd
> --- /dev/null
> +++ b/hw/acpi/vmgenid.c
> @@ -0,0 +1,206 @@
> +/*
> + *  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(GArray *table_data, GArray *guid, BIOSLinker *linker)
> +{
> +    Object *obj;
> +    VmGenIdState *s;
> +    Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx;
> +    uint32_t vgia_offset;
> +
> +    obj = find_vmgenid_dev(NULL);
> +    assert(obj);
> +    s = VMGENID(obj);
> +
> +    /* Fill in the GUID values */
> +    if (guid->len != VMGENID_FW_CFG_SIZE) {
> +        g_array_set_size(guid, VMGENID_FW_CFG_SIZE);
> +    }
> +    g_array_insert_vals(guid, VMGENID_GUID_OFFSET, s->guid.data, 16);

ARRAY_SIZE(s->guid.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) */

/*
 * multiline comments
 * look like this
 */

> +    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 */

add ... so QEMU can write GUID there

> +    bios_linker_loader_add_pointer(linker,
> +        VMGENID_ADDR_FW_CFG_FILE, 0, sizeof(uint32_t),
> +        VMGENID_GUID_FW_CFG_FILE, 0, true);
> +
> +    /* Patch address of GUID fw_cfg blob into the AML */

add ... so OSPM can retrieve and read it

> +    bios_linker_loader_add_pointer(linker,
> +        ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t),
> +        VMGENID_GUID_FW_CFG_FILE, 0, false);
> +
> +    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(FWCfgState *s, GArray *guid)
> +{
> +    Object *obj = find_vmgenid_dev(NULL);
> +    assert(obj);
> +    VmGenIdState *vms = VMGENID(obj);
> +
> +    /* 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,

Seems wrong. What if guest updates the address after command line
set it? You want a callback to copy guid there.


> +                             vms->vgia_le, sizeof(uint32_t), false);

Should be ARRAY_SIZE(vms->vgia_le).

Also, I thought GUID is at an offset from the beginning
in order to trick OVMF, isn't it?


> +}
> +
> +static void vmgenid_update_guest(VmGenIdState *s)
> +{
> +    Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
> +    uint32_t vgia;
> +
> +    if (obj) {
> +        /* Write the GUID to guest memory */
> +        memcpy(&vgia, s->vgia_le, sizeof(vgia));
> +        vgia = le32_to_cpu(vgia);
> +        if (vgia) {

add a comment saying 0 means bios did not run yet.

> +            cpu_physical_memory_write(vgia + VMGENID_GUID_OFFSET,
> +                                      s->guid.data, sizeof(s->guid.data));

Avoid this. You want dma.h APIs.

> +            /* 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 *s = VMGENID(obj);
> +
> +    if (!strncmp(value, "auto", 4)) {

I'd use strcmp here.

> +        qemu_uuid_generate(&s->guid);
> +    } else if (qemu_uuid_parse(value, &s->guid) < 0) {
> +        error_setg(errp, "'%s. %s': Failed to parse GUID string: %s",
> +                   object_get_typename(OBJECT(s)), VMGENID_GUID, value);
> +        return;
> +    }
> +    /* 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, so store that way internally.

This makes my head spin. It's the actual guid, right? Only place we need it is when
we copy it into guest memory. So swap there -
and do it to a copy so you won't need these comments.

>  Make
> +     * sure to swap back whenever reporting via monitor */

And what code does this swap back?

> +    qemu_uuid_bswap(&s->guid);
> +
> +    /* Send the ACPI notify */
> +    vmgenid_update_guest(s);
> +}
> +
> +/* 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 *s = opaque;
> +    vmgenid_update_guest(s);
> +    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(vgia_le, VmGenIdState, sizeof(uint32_t)),
> +        VMSTATE_END_OF_LIST()
> +    },
> +};
> +
> +static void vmgenid_initfn(Object *obj)
> +{
> +    object_property_add_str(obj, VMGENID_GUID, NULL, vmgenid_set_guid, NULL);
> +}
> +
> +static void vmgenid_device_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->vmsd = &vmstate_vmgenid;
> +}
> +
> +static const TypeInfo vmgenid_device_info = {
> +    .name          = VMGENID_DEVICE,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(VmGenIdState),
> +    .instance_init = vmgenid_initfn,
> +    .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 78a1d84..4c40f76 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"
> @@ -2653,6 +2654,11 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
>      acpi_add_table(table_offsets, tables_blob);
>      build_madt(tables_blob, tables->linker, pcms);
>  
> +    if (find_vmgenid_dev(NULL)) {
> +        acpi_add_table(table_offsets, tables_blob);
> +        vmgenid_build_acpi(tables_blob, tables->vmgenid, tables->linker);
> +    }
> +
>      if (misc.has_hpet) {
>          acpi_add_table(table_offsets, tables_blob);
>          build_hpet(tables_blob, tables->linker);
> @@ -2859,6 +2865,10 @@ void acpi_setup(void)
>      fw_cfg_add_file(pcms->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
>                      tables.tcpalog->data, acpi_data_len(tables.tcpalog));
>  
> +    if (find_vmgenid_dev(NULL)) {
> +        vmgenid_add_fw_cfg(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..b60437a
> --- /dev/null
> +++ b/include/hw/acpi/vmgenid.h
> @@ -0,0 +1,37 @@
> +#ifndef ACPI_VMGENID_H
> +#define ACPI_VMGENID_H
> +
> +#include "hw/acpi/bios-linker-loader.h"
> +#include "hw/sysbus.h"
> +#include "qemu/uuid.h"
> +
> +#define VMGENID_DEVICE           "vmgenid"
> +#define VMGENID_GUID             "guid"
> +#define VMGENID_GUID_FW_CFG_FILE      "etc/vmgenid"

Maybe 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 */

ACPI header size is 36 bytes. I'd expect just to use that.
Where does 40 come from? I think it's an 8 bytes alignment requirement.

So do QEMU_ALIGN_UP(sizeof(AcpiTableHeader), 8)

Add a comment explaining that 8.

> +
> +void vmgenid_add_fw_cfg(FWCfgState *s, GArray *guid);
> +void vmgenid_build_acpi(GArray *table_data, GArray *guid, BIOSLinker *linker);
> +
> +#define VMGENID(obj) OBJECT_CHECK(VmGenIdState, (obj), VMGENID_DEVICE)
> +
> +typedef struct VmGenIdState {
> +    SysBusDevice parent_obj;
> +    QemuUUID guid;
> +    uint8_t vgia_le[4];

Please give this fields a better name. Is this the address?
Pls add comments, too.

How about we make it 8 byte so it's future proof?
alternatively put it in a ram block instead.

> +} VmGenIdState;
> +
> +static Object *find_vmgenid_dev(Error **errp)
> +{
> +    Object *obj = object_resolve_path_type("", VMGENID_DEVICE, NULL);
> +    if (!obj && errp) {
> +        error_setg(errp, "%s is not found", VMGENID_DEVICE);
> +    }
> +    return obj;
> +}
> +
> +#endif
> -- 
> 2.7.4