Re: [Qemu-devel] [PATCH 2/8] hw: arm: acpi: Fix incorrect checksums in RSDP

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 26 Nov 2018 17:29:35 +0100
Samuel Ortiz <sameo@linux.intel.com> wrote:

> From: Igor Mammedov <imammedo@redhat.com>
> 
> When RSDP table was introduced (d4bec5d87), we calculated only legacy
> checksum, and that was incorrect as it
>  - specified rev=2 and forgot about extended checksum.
>  - legacy checksum calculated on full table instead of the 1st 20 bytes
> 
> Fix it by adding extended checksum calculation and using correct
> size for legacy checksum.
> 
> While at it use explicit constants to specify sub/full tables
> sizes instead of relying on AcpiRsdpDescriptor size and fields offsets.
> The follow up commits will convert this table to build_append_int_noprefix() API,
> will use constants anyway and remove unused AcpiRsdpDescriptor structure.
> 
> Based on "[PATCH v5 05/24] hw: acpi: Implement XSDT support for  RSDP"
> by Samuel Ortiz, who did it right in his impl.
> 
> Fixes: d4bec5d87 (hw/arm/virt-acpi-build: Generate RSDP table)
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> CC: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> CC: Shannon Zhao <shannon.zhaosl@gmail.com>
> Reviewed-by: Samuel Ortiz <sameo@linux.intel.com>

For future reference, if one re-sends someone else patch, one is supposed to
add his/her own SoB as the last one.

> ---
>  hw/arm/virt-acpi-build.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index fcaa350892..0835900052 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -390,8 +390,13 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned xsdt_tbl_offset)
>  
>      /* Checksum to be filled by Guest linker */
>      bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,
> -        (char *)rsdp - rsdp_table->data, sizeof *rsdp,
> +        (char *)rsdp - rsdp_table->data, 20 /* ACPI rev 1.0 RSDP size */,
>          (char *)&rsdp->checksum - rsdp_table->data);
> +
> +    /* Extended checksum to be filled by Guest linker */
> +    bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,
> +        (char *)rsdp - rsdp_table->data, 36 /* ACPI rev 2.0 RSDP size */,
> +        (char *)&rsdp->extended_checksum - rsdp_table->data);
>  }
>  
>  static void