Re: [Qemu-devel] [PATCH v2 3/6] ACPI: Add Virtual Machine Generation ID support

[Laszlo Ersek <lersek@redhat.com>]

On 01/17/17 14:00, Igor Mammedov wrote:
> On Mon, 16 Jan 2017 11:20:55 -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, and ACPI notify event is sent to the guest
>>
>> The user interface is a simple device with one parameters:
>>  - guid (string, must be 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                  | 207 +++++++++++++++++++++++++++++++++++++
>>  hw/i386/acpi-build.c               |   5 +
>>  hw/misc/Makefile.objs              |   1 +
>>  include/hw/acpi/vmgenid.h          |  24 +++++
>>  7 files changed, 240 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 0b51360..b2bccf6 100644
>> --- a/default-configs/i386-softmmu.mak
>> +++ b/default-configs/i386-softmmu.mak
>> @@ -56,3 +56,4 @@ CONFIG_IOH3420=y
>>  CONFIG_I82801B11=y
>>  CONFIG_SMBIOS=y
>>  CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
>> +CONFIG_ACPI_VMGENID=y
>> diff --git a/default-configs/x86_64-softmmu.mak b/default-configs/x86_64-softmmu.mak
>> index 7f89503..c6bd310 100644
>> --- a/default-configs/x86_64-softmmu.mak
>> +++ b/default-configs/x86_64-softmmu.mak
>> @@ -56,3 +56,4 @@ CONFIG_IOH3420=y
>>  CONFIG_I82801B11=y
>>  CONFIG_SMBIOS=y
>>  CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
>> +CONFIG_ACPI_VMGENID=y
>> diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
>> index 489e63b..7dc95cd 100644
>> --- a/hw/acpi/Makefile.objs
>> +++ b/hw/acpi/Makefile.objs
>> @@ -4,6 +4,7 @@ common-obj-$(CONFIG_ACPI_CPU_HOTPLUG) += cpu_hotplug.o
>>  common-obj-$(CONFIG_ACPI_MEMORY_HOTPLUG) += memory_hotplug.o memory_hotplug_acpi_table.o
>>  common-obj-$(CONFIG_ACPI_CPU_HOTPLUG) += cpu.o
>>  common-obj-$(CONFIG_ACPI_NVDIMM) += nvdimm.o
>> +common-obj-$(CONFIG_ACPI_VMGENID) += vmgenid.o
>>  common-obj-$(CONFIG_ACPI) += acpi_interface.o
>>  common-obj-$(CONFIG_ACPI) += bios-linker-loader.o
>>  common-obj-$(CONFIG_ACPI) += aml-build.o
>> diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
>> new file mode 100644
>> index 0000000..596c8b7
>> --- /dev/null
>> +++ b/hw/acpi/vmgenid.c
>> @@ -0,0 +1,207 @@
>> +/*
>> + *  Virtual Machine Generation ID Device
>> + *
>> + *  Copyright (C) 2016 Skyport Systems.
>> + *
>> + *  Authors: 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"
>> +
>> +Object *find_vmgenid_dev(Error **errp)
>> +{
>> +    Object *obj = object_resolve_path_type("", VMGENID_DEVICE, NULL);
>> +    if (!obj) {
>> +        error_setg(errp, VMGENID_DEVICE " is not found");
>> +    }
>> +    return obj;
>> +}
>> +
>> +void vmgenid_build_acpi(GArray *table_offsets, GArray *table_data,
>> +        BIOSLinker *linker)
> wrong alignment, should be
> 
>    f12345(arg1,
>           arg2);
>   
>> +{
>> +    Object *obj = find_vmgenid_dev(NULL);
>> +    if (!obj) {
>> +        return;
>> +    }
>> +    VmGenIdState *s = VMGENID(obj);
>> +
>> +    acpi_add_table(table_offsets, table_data);
>> +
>> +    GArray *guid = g_array_new(false, true, sizeof(s->guid.data));
>> +    g_array_append_val(guid, s->guid.data);
>> +
>> +    Aml *ssdt, *dev, *scope, *pkg, *method;
> Pls read CODING_STYLE and amend patch accordingly.
> 
>> +
>> +    /* 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 */
>> +    uint32_t vgia_offset = table_data->len +
>> +        build_append_named_qword(ssdt->buf, "VGIA");
>> +    dev = aml_device("VGEN");
>> +    scope = aml_scope("\\_SB");
> swap scope and dev
> 
>> +    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);
>> +    Aml *if_ctx = aml_if(aml_equal(aml_name("VGIA"), aml_int(0)));
>> +    aml_append(if_ctx, aml_return(aml_int(0)));
>> +    aml_append(method, if_ctx);
>> +    Aml *else_ctx = aml_else();
>> +    aml_append(else_ctx, aml_return(aml_int(0xf)));
>> +    aml_append(method, else_ctx);
>> +    aml_append(dev, method);
> it would be cleaner if written like:
> 
> local0 = 0xf
> if (vgia == 0) {
>    local0 = 0
> }
> return local0
> 
>> +
>> +    /* 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);
>> +
>> +    pkg = aml_package(2);
>> +    aml_append(pkg, aml_int(0));
>> +    aml_append(pkg, aml_int(0));
>> +
>> +    aml_append(method, aml_name_decl("LPKG", pkg));
> creating named object in method requires method be serialized, however
> there is no need to create named variable here, just use localX instead
> 
> like:
>    addr = aml_local(0)
>    store(pkg, addr)
> 
>> +    aml_append(method, aml_store(aml_and(aml_name("VGIA"),
>> +        aml_int(0xffffffff), NULL), aml_index(aml_name("LPKG"), aml_int(0))));
> then instead of aml_name("LPKG") it would become just 'addr'
> 
>> +    aml_append(method, aml_store(aml_shiftright(aml_name("VGIA"),
>> +        aml_int(32), NULL), aml_index(aml_name("LPKG"), aml_int(1))));
>> +    aml_append(method, aml_return(aml_name("LPKG")));
>> +
>> +    aml_append(dev, method);
>> +    aml_append(scope, dev);
>> +    aml_append(ssdt, scope);
>> +
>> +    /* attach an ACPI notify */
>> +    scope = aml_scope("_GPE");
>> +    method = aml_method("_E00", 0, AML_NOTSERIALIZED);
> I don't recall reason why _E00 isn't used but to be safe maybe next unused
> would be better (it seems to be _E05)

I searched my mailbox, and found this earlier discussion:

https://www.mail-archive.com/qemu-devel@nongnu.org/msg347337.html

If I understand correctly, we shouldn't expose _E00 and _L00 at the same
time.

> 
>> +    aml_append(method, aml_notify(aml_name("\\_SB.VGEN"), aml_int(0x80)));
>> +    aml_append(scope, method);
>> +    aml_append(ssdt, scope);
> you actually can skip scopes by providing full path in device/method name, like
> 
>   aml_method("\\_GPE._E05", ...
> 
>> +
>> +    /* copy AML table into ACPI tables blob and patch in fw_cfg blob */
>> +    g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
>> +    bios_linker_loader_alloc(linker, VMGENID_FW_CFG_FILE, guid, 0,
>> +                             false /* high memory */);
>> +    bios_linker_loader_add_pointer(linker,
>> +        ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint64_t),
>> +        VMGENID_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(FWCfgState *s)
>> +{
>> +    Object *obj = find_vmgenid_dev(NULL);
>> +    if (!obj) {
>> +        return;
>> +    }
>> +    VmGenIdState *vms = VMGENID(obj);
>> +    fw_cfg_add_file(s, VMGENID_FW_CFG_FILE, vms->guid.data,
>> +        sizeof(vms->guid.data));
>> +}
>> +
>> +static void vmgenid_notify_guest(VmGenIdState *s)
>> +{
>> +    Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
>> +    if (obj) {
>> +        /* Send _GPE.E00 event */
>> +        acpi_send_event(DEVICE(obj), 1 << 0);
>> +    }
>> +}
>> +
>> +static void vmgenid_set_guid(Object *obj, const char *value, Error **errp)
>> +{
>> +    VmGenIdState *s = VMGENID(obj);
>> +
>> +    if (qemu_uuid_parse(value, &s->guid) < 0) {
>> +        error_setg(errp, "'%s." VMGENID_GUID
>> +                   "': Failed to parse GUID string: %s",
>> +                   object_get_typename(OBJECT(s)),
>> +                   value);
>> +        return;
>> +    }
> here should be code that would copy new GIUD to
> buffer allocated by firmware and then after that don't forget
> call memory_region_set_dirty() on it.
> 
> Question is how you'd get address of it and I think that's where
> writable fwcfg files come in play.

I think so, yes.

> I'd prefer fwcfg_loader in firmware to write it back after buffer
> allocation is done as it's already has utilities for fw_cfg,
> but that probably would mean extending loader protocol to support
> new writeback command.

I think it's technically possible, yes.

Thanks
Laszlo

> 
> PS, address one would get from guest should be migrated as well
> 
> 
>> +    vmgenid_notify_guest(s);
>> +}
>> +
>> +static void vmgenid_state_change(void *priv, int running, RunState state)
>> +{
>> +    VmGenIdState *s;
>> +
>> +    if (state != RUN_STATE_RUNNING) {
>> +        return;
>> +    }
>> +    s = VMGENID((Object *)priv);
>> +    vmgenid_notify_guest(s);
>> +}
>> +
>> +static void vmgenid_initfn(Object *obj)
>> +{
>> +    object_property_add_str(obj, VMGENID_GUID, NULL, vmgenid_set_guid, NULL);
>> +    qemu_add_vm_change_state_handler(vmgenid_state_change, obj);
>> +}
>> +
>> +static const TypeInfo vmgenid_device_info = {
>> +    .name          = VMGENID_DEVICE,
>> +    .parent        = TYPE_SYS_BUS_DEVICE,
>> +    .instance_size = sizeof(VmGenIdState),
>> +    .instance_init = vmgenid_initfn,
>> +};
>> +
>> +static void vmgenid_register_types(void)
>> +{
>> +    type_register_static(&vmgenid_device_info);
>> +}
>> +
>> +type_init(vmgenid_register_types)
>> +
>> +GuidInfo *qmp_query_vm_generation_id(Error **errp)
>> +{
>> +    GuidInfo *info;
>> +    VmGenIdState *vdev;
>> +    Object *obj = find_vmgenid_dev(errp);
>> +
>> +    if (!obj) {
>> +        return NULL;
>> +    }
>> +    vdev = VMGENID(obj);
>> +    info = g_malloc0(sizeof(*info));
>> +    info->guid = g_strdup_printf(UUID_FMT, vdev->guid.data[0],
>> +            vdev->guid.data[1], vdev->guid.data[2], vdev->guid.data[3],
>> +            vdev->guid.data[4], vdev->guid.data[5], vdev->guid.data[6],
>> +            vdev->guid.data[7], vdev->guid.data[8], vdev->guid.data[9],
>> +            vdev->guid.data[10], vdev->guid.data[11], vdev->guid.data[12],
>> +            vdev->guid.data[13], vdev->guid.data[14], vdev->guid.data[15]);
> 
> perhaps qemu_uuid_unparse_strdup() could be used
> 
>> +    return info;
>> +}
>> +
>> +void qmp_set_vm_generation_id(const char *guid, Error **errp)
>> +{
>> +    Object *obj = find_vmgenid_dev(errp);
>> +
>> +    if (!obj) {
>> +        return;
>> +    }
>> +
>> +    object_property_set_str(obj, guid, VMGENID_GUID, errp);
>> +    return;
>> +}
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index 9708cdc..cde81b7 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"
>> @@ -2785,6 +2786,8 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
>>      acpi_add_table(table_offsets, tables_blob);
>>      build_madt(tables_blob, tables->linker, pcms);
>>  
> if (has_vmgenid()) {
>> +    vmgenid_build_acpi(table_offsets, tables_blob, tables->linker);
> }
> 
> and remove similar check for called function
> 
>> +
>>      if (misc.has_hpet) {
>>          acpi_add_table(table_offsets, tables_blob);
>>          build_hpet(tables_blob, tables->linker);
>> @@ -2991,6 +2994,8 @@ void acpi_setup(void)
>>      fw_cfg_add_file(pcms->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
>>                      tables.tcpalog->data, acpi_data_len(tables.tcpalog));
>>  
>> +    vmgenid_add_fw_cfg(pcms->fw_cfg);
> ditto
> 
>> +
>>      if (!pcmc->rsdp_in_ram) {
>>          /*
>>           * Keep for compatibility with old machine types.
>> diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
>> index 1a89615..ca0f1bb 100644
>> --- a/hw/misc/Makefile.objs
>> +++ b/hw/misc/Makefile.objs
>> @@ -53,3 +53,4 @@ obj-$(CONFIG_EDU) += edu.o
>>  obj-$(CONFIG_HYPERV_TESTDEV) += hyperv_testdev.o
>>  obj-$(CONFIG_AUX) += auxbus.o
>>  obj-$(CONFIG_ASPEED_SOC) += aspeed_scu.o aspeed_sdmc.o
>> +obj-$(CONFIG_VMGENID) += vmgenid.o
>> diff --git a/include/hw/acpi/vmgenid.h b/include/hw/acpi/vmgenid.h
>> new file mode 100644
>> index 0000000..f8bdff2
>> --- /dev/null
>> +++ b/include/hw/acpi/vmgenid.h
>> @@ -0,0 +1,24 @@
>> +#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_FW_CFG_FILE      "etc/vmgenid"
>> +
>> +Object *find_vmgenid_dev(Error **errp);
>> +void vmgenid_add_fw_cfg(FWCfgState *s);
>> +void vmgenid_build_acpi(GArray *table_offsets, GArray *table_data,
>> +                       BIOSLinker *linker);
>> +
>> +#define VMGENID(obj) OBJECT_CHECK(VmGenIdState, (obj), VMGENID_DEVICE)
>> +
>> +typedef struct VmGenIdState {
>> +    SysBusDevice parent_obj;
>> +    QemuUUID guid;
>> +} VmGenIdState;
>> +
>> +#endif
>