Re: [PATCH v3 1/4] acpi: Convert build_tpm2() to build_append* API

[Auger Eric <eric.auger@redhat.com>]

Hi Igor,

On 6/5/20 4:23 PM, Igor Mammedov wrote:
> On Mon,  1 Jun 2020 11:57:34 +0200
> Eric Auger <eric.auger@redhat.com> wrote:
> 
>> In preparation of its move to the generic acpi code,
>> let's convert build_tpm2() to use build_append API. This
>> latter now is prefered in place of direct ACPI struct field
>> settings with manual endianness conversion.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> ---
>>  hw/i386/acpi-build.c | 28 +++++++++++++++++++---------
>>  1 file changed, 19 insertions(+), 9 deletions(-)
>>
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index b5669d6c65..f0d35d7b17 100644
>> --- a/hw/i386/acpi-build.c
>> +++ b/hw/i386/acpi-build.c
>> @@ -2298,30 +2298,40 @@ build_tpm_tcpa(GArray *table_data, BIOSLinker *linker, GArray *tcpalog)
>>  static void
>>  build_tpm2(GArray *table_data, BIOSLinker *linker, GArray *tcpalog)
>>  {
>> -    Acpi20TPM2 *tpm2_ptr = acpi_data_push(table_data, sizeof *tpm2_ptr);
>> +    Acpi20TPM2 *tpm2_ptr = acpi_data_push(table_data, sizeof(AcpiTableHeader));
> 
>>      unsigned log_addr_size = sizeof(tpm2_ptr->log_area_start_address);
>>      unsigned log_addr_offset =
>>          (char *)&tpm2_ptr->log_area_start_address - table_data->data;
> 
> Is this the reason why you've kept Acpi20TPM2 around?
Yes it is
> 
> 
>> +    uint8_t start_method_params[12] = {};
>>  
>> -    tpm2_ptr->platform_class = cpu_to_le16(TPM2_ACPI_CLASS_CLIENT);
>> +    /* platform class */
> pls verbatim filed names from spec in comments
Do you want "Platform Class" instead?
> 
>> +    build_append_int_noprefix(table_data, TPM2_ACPI_CLASS_CLIENT, 2);
>> +    /* reserved */
>> +    build_append_int_noprefix(table_data, 0, 2);
>>      if (TPM_IS_TIS_ISA(tpm_find())) {
>> -        tpm2_ptr->control_area_address = cpu_to_le64(0);
>> -        tpm2_ptr->start_method = cpu_to_le32(TPM2_START_METHOD_MMIO);
>> +        /* address of control area */
>> +        build_append_int_noprefix(table_data, 0, 8);
>> +        /* start method */
>> +        build_append_int_noprefix(table_data, TPM2_START_METHOD_MMIO, 4);
>>      } else if (TPM_IS_CRB(tpm_find())) {
>> -        tpm2_ptr->control_area_address = cpu_to_le64(TPM_CRB_ADDR_CTRL);
>> -        tpm2_ptr->start_method = cpu_to_le32(TPM2_START_METHOD_CRB);
> 
> missing field name comments
OK
> 
>> +        build_append_int_noprefix(table_data, TPM_CRB_ADDR_CTRL, 8);
>> +        build_append_int_noprefix(table_data, TPM2_START_METHOD_CRB, 4);
>>      } else {
>>          g_warn_if_reached();
>>      }
> 
> considering fields are the same I'd also restructure above as
>     if () {
>        control_area_address = 
>        start_method =
>     ...
>     }
>     /* address of control area */
>     build_append_int_noprefix(table_data, control_area_address, 8);
>     /* start method */
>     build_append_int_noprefix(table_data, start_method, 4); 
> 
> which is bit easier to read 
OK
>     
>>  
>> -    tpm2_ptr->log_area_minimum_length =
>> -        cpu_to_le32(TPM_LOG_AREA_MINIMUM_SIZE);
>> +    /* platform specific parameters */
>> +    g_array_append_vals(table_data, &start_method_params, 12);
>>  
>> -    acpi_data_push(tcpalog, le32_to_cpu(tpm2_ptr->log_area_minimum_length));
>> +    /* log area minimum length */
>> +    build_append_int_noprefix(table_data, TPM_LOG_AREA_MINIMUM_SIZE, 4);
>> +
>> +    acpi_data_push(tcpalog, TPM_LOG_AREA_MINIMUM_SIZE);
>>      bios_linker_loader_alloc(linker, ACPI_BUILD_TPMLOG_FILE, tcpalog, 1,
>>                               false);
> 
> I suggest to drop Acpi20TPM2 with pointer math above and use approach similar
> to build_ghes_v2/address_offset, i.e. get actual offest here:
> 
>       log_addr_offset = table_data->len
yes, that's simpler. Thank you for the suggestion.
> 
> and s/log_addr_size/8/
OK

Thanks

Eric
> 
>>      /* log area start address to be filled by Guest linker */
>> +    build_append_int_noprefix(table_data, 0, 8);
>>      bios_linker_loader_add_pointer(linker, ACPI_BUILD_TABLE_FILE,
>>                                     log_addr_offset, log_addr_size,
>>                                     ACPI_BUILD_TPMLOG_FILE, 0);
>