Re: [PATCH v4 15/35] acpi: build_tpm_tcpa: use acpi_table_begin()/acpi_table_end() instead of build_header()

[Stefan Berger]

On 9/24/21 8:27 AM, Igor Mammedov wrote:

> it replaces error-prone pointer arithmetic for build_header() API,
> with 2 calls to start and finish table creation,
> which hides offsets magic from API user.
>
> While at it switch to build_append_int_noprefix() to build
> table entries (which also removes some manual offset
> calculations).
>
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>

Tested-by: Stefan Berger <stefanb@linux.ibm.com>


> ---
> v2:
>    * fix assert when starting QEMU with TPM 1.2
>        Stefan Berger <stefanb@linux.ibm.com>
> v3:
>   * fix invalid checksum, by putting acpi_table_composed()
>     after pointer patching
>   * s/acpi_init_table|acpi_table_composed/acpi_table_begin|acpi_table_end/
>
> CC: stefanb@linux.vnet.ibm.com
> ---
>   include/hw/acpi/acpi-defs.h | 14 --------------
>   hw/i386/acpi-build.c        | 38 ++++++++++++++++++++++---------------
>   2 files changed, 23 insertions(+), 29 deletions(-)
>
> diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
> index 4d8f8b34b0..3b42b138f0 100644
> --- a/include/hw/acpi/acpi-defs.h
> +++ b/include/hw/acpi/acpi-defs.h
> @@ -418,20 +418,6 @@ struct AcpiSratProcessorGiccAffinity {
>
>   typedef struct AcpiSratProcessorGiccAffinity AcpiSratProcessorGiccAffinity;
>
> -/*
> - * TCPA Description Table
> - *
> - * Following Level 00, Rev 00.37 of specs:
> - * http://www.trustedcomputinggroup.org/resources/tcg_acpi_specification
> - */
> -struct Acpi20Tcpa {
> -    ACPI_TABLE_HEADER_DEF                    /* ACPI common table header */
> -    uint16_t platform_class;
> -    uint32_t log_area_minimum_length;
> -    uint64_t log_area_start_address;
> -} QEMU_PACKED;
> -typedef struct Acpi20Tcpa Acpi20Tcpa;
> -
>   /* DMAR - DMA Remapping table r2.2 */
>   struct AcpiTableDmar {
>       ACPI_TABLE_HEADER_DEF
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 1587fe5a20..9fa6d7665b 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1878,31 +1878,39 @@ build_hpet(GArray *table_data, BIOSLinker *linker, 
> const char *oem_id,
>   }
>
>   #ifdef CONFIG_TPM
> +/*
> + * TCPA Description Table
> + *
> + * Following Level 00, Rev 00.37 of specs:
> + * http://www.trustedcomputinggroup.org/resources/tcg_acpi_specification
> + * 7.1.2 ACPI Table Layout
> + */
>   static void
>   build_tpm_tcpa(GArray *table_data, BIOSLinker *linker, GArray *tcpalog,
>                  const char *oem_id, const char *oem_table_id)
>   {
> -    int tcpa_start = table_data->len;
> -    Acpi20Tcpa *tcpa = acpi_data_push(table_data, sizeof *tcpa);
> -    unsigned log_addr_size = sizeof(tcpa->log_area_start_address);
> -    unsigned log_addr_offset =
> -        (char *)&tcpa->log_area_start_address - table_data->data;
> +    unsigned log_addr_offset;
> +    AcpiTable table = { .sig = "TCPA", .rev = 2,
> +                        .oem_id = oem_id, .oem_table_id = oem_table_id };
>
> -    tcpa->platform_class = cpu_to_le16(TPM_TCPA_ACPI_CLASS_CLIENT);
> -    tcpa->log_area_minimum_length = cpu_to_le32(TPM_LOG_AREA_MINIMUM_SIZE);
> -    acpi_data_push(tcpalog, le32_to_cpu(tcpa->log_area_minimum_length));
> +    acpi_table_begin(&table, table_data);
> +    /* Platform Class */
> +    build_append_int_noprefix(table_data, TPM_TCPA_ACPI_CLASS_CLIENT, 2);
> +    /* Log Area Minimum Length (LAML) */
> +    build_append_int_noprefix(table_data, TPM_LOG_AREA_MINIMUM_SIZE, 4);
> +    /* Log Area Start Address (LASA) */
> +    log_addr_offset = table_data->len;
> +    build_append_int_noprefix(table_data, 0, 8);
>
> +    /* allocate/reserve space for TPM log area */
> +    acpi_data_push(tcpalog, TPM_LOG_AREA_MINIMUM_SIZE);
>       bios_linker_loader_alloc(linker, ACPI_BUILD_TPMLOG_FILE, tcpalog, 1,
>                                false /* high memory */);
> -
>       /* log area start address to be filled by Guest linker */
> -    bios_linker_loader_add_pointer(linker,
> -        ACPI_BUILD_TABLE_FILE, log_addr_offset, log_addr_size,
> -        ACPI_BUILD_TPMLOG_FILE, 0);
> +    bios_linker_loader_add_pointer(linker, ACPI_BUILD_TABLE_FILE,
> +        log_addr_offset, 8, ACPI_BUILD_TPMLOG_FILE, 0);
>
> -    build_header(linker, table_data,
> -                 (void *)(table_data->data + tcpa_start),
> -                 "TCPA", sizeof(*tcpa), 2, oem_id, oem_table_id);
> +    acpi_table_end(linker, &table);
>   }
>   #endif