Re: [PATCH v2 0/3] Correct for ACPI 5.1->6.0 spec changes in MADT GICC entries

From: Al Stone
Date: Fri Jun 19 2015 - 16:05:45 EST

On 06/19/2015 04:54 AM, Hanjun Guo wrote:
> On 06/19/2015 06:36 AM, Al Stone wrote:
>> In the ACPI 5.1 version of the spec, the struct for the GICC subtable
>> (struct acpi_madt_generic_interrupt) of the MADT is 76 bytes long; in
>> ACPI 6.0, the struct is 80 bytes long. But, there is only one definition
>> in ACPICA for this struct -- and that is the 6.0 version. Hence, when
>> BAD_MADT_ENTRY() compares the struct size to the length in the GICC
>> subtable, it fails if 5.1 structs are in use, and there are systems in
>> the wild that have them.
>> Note that this was found in linux-next and these patches apply against
>> that tree and the arm64 kernel tree; 4.1-rc8 does not appear to have this
>> problem since it still has the 5.1 struct definition.
>> Even though there is precendent in ia64 code for ignoring the changes in
>> size, this patch set instead tries to verify correctness. The first patch
>> in the set adds macros for easily using the ACPI spec version. The second
>> patch adds the BAD_MADT_GICC_ENTRY() macro that uses the version macros to
>> check the GICC subtable only, accounting for the difference in specification
>> versions that are possible. The final patch replaces BAD_MADT_ENTRY usage
>> with the BAD_MADT_GICC_ENTRY macro in arm64 code, which is currently the
>> only architecture affected. The BAD_MADT_ENTRY() will continue to work as
>> is for all other MADT subtables.
>> I have tested these patches on an APM Mustang with version 1.15 firmware,
>> where the problem was found, and they fix the problem.
> I also tested on QEMU, it fixed the problem when I was using ACPICA 6.0
> updates for MADT table,
> Tested-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> Thanks
> Hanjun

Cool. The patches did what they should. Looks like they work on AMD
Seattle with older firmware, also. Thanks.

>> Changes for v2:
>> -- Replace magic constants with proper defines (Lorenzo)
>> -- Minor syntax clean-up noted by checkpatch
>> -- Send out CCs properly this time
>> -- Minor clean-up of the paragraphs in this cover letter
>> Al Stone (3):
>> ACPI : introduce macros for using the ACPI specification version
>> ACPI: add BAD_MADT_GICC_ENTRY() macro
>> ACPI / ARM64 : use the new BAD_MADT_GICC_ENTRY macro
>> arch/arm64/kernel/smp.c | 2 +-
>> drivers/irqchip/irq-gic.c | 2 +-
>> include/linux/acpi.h | 15 +++++++++++++++
>> 3 files changed, 17 insertions(+), 2 deletions(-)
> --
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Al Stone
Software Engineer
Red Hat, Inc.
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