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

[Igor Mammedov]

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?


> +    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

> +    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

> +        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 
    
>  
> -    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

and s/log_addr_size/8/

>      /* 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);