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


From: Igor Mammedov
Subject: Re: [Qemu-devel] [PATCH v2 3/6] ACPI: Add Virtual Machine Generation ID support
Date: Tue, 17 Jan 2017 14:00:58 +0100

On Mon, 16 Jan 2017 11:20:55 -0800
address@hidden wrote:

> From: Ben Warren <address@hidden>
> 
> 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 <address@hidden>
> ---
>  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 <address@hidden>
> + *
> + * 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)

> +    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'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.

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




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