Re: [PATCH v3 12/35] acpi: vmgenid_build_acpi: use acpi_table_begin()/acpi_table_end() instead of build_header()

[Eric Auger]

On 9/7/21 4:47 PM, 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.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
> v3:
>   * s/acpi_init_table|acpi_table_composed/acpi_table_begin|acpi_table_end/
> ---
>  hw/acpi/vmgenid.c | 16 +++++++---------
>  1 file changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
> index 4f41a13ea0..95f94a2510 100644
> --- a/hw/acpi/vmgenid.c
> +++ b/hw/acpi/vmgenid.c
> @@ -29,6 +29,8 @@ void vmgenid_build_acpi(VmGenIdState *vms, GArray 
> *table_data, GArray *guid,
>      Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx;
>      uint32_t vgia_offset;
>      QemuUUID guid_le;
> +    AcpiTable table = { .sig = "SSDT", .rev = 1,
> +                        .oem_id = oem_id, .oem_table_id = "VMGENID" };
>  
>      /* Fill in the GUID values.  These need to be converted to little-endian
>       * first, since that's what the guest expects
> @@ -42,15 +44,12 @@ void vmgenid_build_acpi(VmGenIdState *vms, GArray 
> *table_data, GArray *guid,
>      g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data,
>                          ARRAY_SIZE(guid_le.data));
>  
> -    /* Put this in a separate SSDT table */
> +    /* Put VMGNEID into a separate SSDT table */
> +    acpi_table_begin(&table, table_data);
>      ssdt = init_aml_allocator();
>  
> -    /* Reserve space for header */
> -    acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
> -
>      /* Storage for the GUID address */
> -    vgia_offset = table_data->len +
> -        build_append_named_dword(ssdt->buf, "VGIA");
> +    vgia_offset = table_data->len + build_append_named_dword(ssdt->buf, 
> "VGIA");
not mandated but well

>      scope = aml_scope("\\_SB");
>      dev = aml_device("VGEN");
>      aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVGID")));
> @@ -116,9 +115,8 @@ void vmgenid_build_acpi(VmGenIdState *vms, GArray 
> *table_data, GArray *guid,
>          ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t),
>          VMGENID_GUID_FW_CFG_FILE, 0);
>  
> -    build_header(linker, table_data,
> -        (void *)(table_data->data + table_data->len - ssdt->buf->len),
> -        "SSDT", ssdt->buf->len, 1, oem_id, "VMGENID");
> +    /* must be called after above command to ensure correct table checksum */
ditto
> +    acpi_table_end(linker, &table);
>      free_aml_allocator();
>  }
>  
> 
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric