Re: [Qemu-devel] [PATCH v3 2/4] acpi: add fw_cfg file for TPM and PPI virtual memory device

[Laszlo Ersek]

On 06/21/18 12:10, Marc-André Lureau wrote:
> Hi
> 
> On Thu, Jun 21, 2018 at 12:00 PM, Igor Mammedov <address@hidden> wrote:
>> On Tue, 15 May 2018 14:14:31 +0200
>> Marc-André Lureau <address@hidden> wrote:
>>
>>> From: Stefan Berger <address@hidden>
>>>
>>> To avoid having to hard code the base address of the PPI virtual
>>> memory device we introduce a fw_cfg file etc/tpm/config that holds the
>>> base address of the PPI device, the version of the PPI interface and
>>> the version of the attached TPM.
>> is it related to TPM_PPI_ADDR_BASE added in previous patch?
>>
>>>
>>> Signed-off-by: Stefan Berger <address@hidden>
>>> [ Marc-André: renamed to etc/tpm/config, made it static, document it ]
>>> Signed-off-by: Marc-André Lureau <address@hidden>
>>> ---
>>>  include/hw/acpi/tpm.h |  3 +++
>>>  hw/i386/acpi-build.c  | 17 +++++++++++++++++
>>>  docs/specs/tpm.txt    | 20 ++++++++++++++++++++
>>>  3 files changed, 40 insertions(+)
>>>
>>> diff --git a/include/hw/acpi/tpm.h b/include/hw/acpi/tpm.h
>>> index c082df7d1d..f79d68a77a 100644
>>> --- a/include/hw/acpi/tpm.h
>>> +++ b/include/hw/acpi/tpm.h
>>> @@ -193,4 +193,7 @@ REG32(CRB_DATA_BUFFER, 0x80)
>>>  #define TPM_PPI_ADDR_SIZE           0x400
>>>  #define TPM_PPI_ADDR_BASE           0xFED45000
>>>
>>> +#define TPM_PPI_VERSION_NONE        0
>>> +#define TPM_PPI_VERSION_1_30        1
>>> +
>>>  #endif /* HW_ACPI_TPM_H */
>>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>>> index 9bc6d97ea1..f6d447f03a 100644
>>> --- a/hw/i386/acpi-build.c
>>> +++ b/hw/i386/acpi-build.c
>>> @@ -119,6 +119,12 @@ typedef struct AcpiBuildPciBusHotplugState {
>>>      bool pcihp_bridge_en;
>>>  } AcpiBuildPciBusHotplugState;
>>>
>>> +typedef struct FWCfgTPMConfig {
>>> +    uint32_t tpmppi_address;
>>> +    uint8_t tpm_version;
>>> +    uint8_t tpmppi_version;
>>> +} QEMU_PACKED FWCfgTPMConfig;
>>> +
>>>  static void init_common_fadt_data(Object *o, AcpiFadtData *data)
>>>  {
>>>      uint32_t io = object_property_get_uint(o, ACPI_PM_PROP_PM_IO_BASE, 
>>> NULL);
>>> @@ -2873,6 +2879,7 @@ void acpi_setup(void)
>>>      AcpiBuildTables tables;
>>>      AcpiBuildState *build_state;
>>>      Object *vmgenid_dev;
>>> +    static FWCfgTPMConfig tpm_config;
>>>
>>>      if (!pcms->fw_cfg) {
>>>          ACPI_BUILD_DPRINTF("No fw cfg. Bailing out.\n");
>>> @@ -2907,6 +2914,16 @@ void acpi_setup(void)
>>>      fw_cfg_add_file(pcms->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
>>>                      tables.tcpalog->data, acpi_data_len(tables.tcpalog));
>>>
>>> +    if (tpm_find()) {
>>> +        tpm_config = (FWCfgTPMConfig) {
>>> +            .tpmppi_address = cpu_to_le32(TPM_PPI_ADDR_BASE),
>>> +            .tpm_version = cpu_to_le32(tpm_get_version(tpm_find())),
>>> +            .tpmppi_version = cpu_to_le32(TPM_PPI_VERSION_NONE)
>>> +        };
>>> +        fw_cfg_add_file(pcms->fw_cfg, "etc/tpm/config",
>>> +                        &tpm_config, sizeof tpm_config);
>>> +    }
>> why it's in ACPI part of the code, shouldn't it be a part of device,
>> could TPM be used without ACPI at all (-noacpi CLI option)?
>>
>> Wouldn't adding fwcfg entry unconditionally break migration?
> 
> Because of unstable entry IDs? that could be problematic. (especially
> during boot time) What do you think Laszlo?
> 
> I guess we could have a "ppi" device property, that would imply having
> the etc/tpm/config fw_cfg entry. We would enable it by default in
> newer machine types (3.0?)

Can we perhaps draw a parallel with "-device vmcoreinfo" here? For that
device model, fw_cfg_add_file_callback() is called in the realize
function, vmcoreinfo_realize(). If libvirt generates the identical
cmdline on both ends of the migration, and uses the same machine type, I
think the fw_cfg selectors should end up the same on both sides.

Thanks
Laszlo

>>
>>> +
>>>      vmgenid_dev = find_vmgenid_dev();
>>>      if (vmgenid_dev) {
>>>          vmgenid_add_fw_cfg(VMGENID(vmgenid_dev), pcms->fw_cfg,
>>> diff --git a/docs/specs/tpm.txt b/docs/specs/tpm.txt
>>> index c230c4c93e..2ddb768084 100644
>>> --- a/docs/specs/tpm.txt
>>> +++ b/docs/specs/tpm.txt
>>> @@ -20,6 +20,26 @@ QEMU files related to TPM TIS interface:
>>>   - hw/tpm/tpm_tis.h
>>>
>>>
>>> += fw_cfg interface =
>>> +
>>> +The bios/firmware may use the "etc/tpm/config" fw_cfg entry for
>>> +configuring the guest appropriately.
>>> +
>>> +The entry of 6 bytes has the following content, in little-endian:
>>> +
>>> +    #define TPM_VERSION_UNSPEC          0
>>> +    #define TPM_VERSION_1_2             1
>>> +    #define TPM_VERSION_2_0             2
>>> +
>>> +    #define TPM_PPI_VERSION_NONE        0
>>> +    #define TPM_PPI_VERSION_1_30        1
>>> +
>>> +    struct FWCfgTPMConfig {
>>> +        uint32_t tpmppi_address;         /* PPI memory location */
>>> +        uint8_t tpm_version;             /* TPM version */
>>> +        uint8_t tpmppi_version;          /* PPI version */
>>> +    };
>>> +
>>>  = ACPI Interface =
>>>
>>>  The TPM device is defined with ACPI ID "PNP0C31". QEMU builds a SSDT and 
>>> passes
>>
>>
> 
> 
>