[PATCH] acpi: madt: Fix ITS subtable length check

[Jeffrey Hugo]

On 7/14/2016 12:50 AM, Alex Hung wrote:
> On 2016-07-14 02:41 AM, Jeffrey Hugo wrote:
>> The ACPI spec defines the MADT GIC ITS subtable length as 20 bytes.  The
>> test is checking to see if the subtable is 16 bytes in length which
>> causes
>> an invalid test failure for MADT tables with GIC ITS subtables that
>> follow
>> the spec.
>>
>> Signed-off-by: Jeffrey Hugo <jhugo at codeaurora.org>
>> ---
>>   src/acpi/madt/madt.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/src/acpi/madt/madt.c b/src/acpi/madt/madt.c
>> index b65b89e..65d3962 100644
>> --- a/src/acpi/madt/madt.c
>> +++ b/src/acpi/madt/madt.c
>> @@ -183,7 +183,7 @@ static struct acpi_madt_subtable_lengths
>> spec_info[] = {
>>           .madt_version = 3,
>>           .num_types = 16,
>>           .lengths = { 8, 12, 10, 8, 6, 12, 16, SUBTABLE_VARIABLE,
>> -                 16, 16, 12, 80, 24, 24, 16, 16 }
>> +                 16, 16, 12, 80, 24, 24, 16, 20 }
>>       },
>
> Hi Jeffrey,
>
> Thanks a lot for pointing this out.
>
> I noticed the ITS's length is 16 in ACPI 6.0 and it is updated to 20 in
> ACPI 6.1 (See revision history "1487 The Length of GIC ITS Structure is
> wrong"). However, the madt's revision also changed from 3 to 4

Drat, I must have missed that.  Thanks for pointing it out.

>
> 1. talk about to this change in this patch
> 2. keep the original structure and add a new structure for revision 4, ex.
> { /* for ACPI 6.0 */
> .major_version = 6,
> .minor_version = 0,
> .madt_version = 3,
> .num_types = 16,
> .lengths = { 8, 12, 10, 8, 6, 12, 16, SUBTABLE_VARIABLE,
> 16, 16, 12, 80, 24, 24, 16, 16 }
> },
> { /* for ACPI 6.1 */
> .major_version = 6,
> .minor_version = 0,
> .madt_version = 4,
> .num_types = 16,
> .lengths = { 8, 12, 10, 8, 6, 12, 16, SUBTABLE_VARIABLE,
> 16, 16, 12, 80, 24, 24, 16, 20 }

Off the top of my head, this appears to make sense, but I'll play around 
with it while we wait for Al to commment.

>
> Hi Al,
>
> Will you be able to give some suggestions?
>
>
>>       { /* terminator */
>>           .major_version = 0,
>>
>
>


-- 
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm 
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.