Re: [PATCH v2 5/7] xen/arm: acpi: add BAD_MADT_GICC_ENTRY() macro

From: Julien Grall <julien@xen.org>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: xen-devel@lists.xenproject.org, alex.bennee@linaro.org,
	masami.hiramatsu@linaro.org, ehem+xen@m5p.com,
	bertrand.marquis@arm.com, andre.przywara@arm.com,
	Rahul.Singh@arm.com, Julien Grall <julien.grall@arm.com>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
	Julien Grall <jgrall@amazon.com>
Subject: Re: [PATCH v2 5/7] xen/arm: acpi: add BAD_MADT_GICC_ENTRY() macro
Date: Fri, 30 Oct 2020 18:46:59 +0000	[thread overview]
Message-ID: <1bdbd2bd-5bcf-cd9a-f9bc-6239c050b595@xen.org> (raw)
In-Reply-To: <alpine.DEB.2.21.2010231719520.12247@sstabellini-ThinkPad-T480s>

Hi Stefano,

On 24/10/2020 01:32, Stefano Stabellini wrote:
> On Fri, 23 Oct 2020, Julien Grall wrote:
>> From: Julien Grall <julien.grall@arm.com>
>>
>> Imported from Linux commit b6cfb277378ef831c0fa84bcff5049307294adc6:
>>
>>      The BAD_MADT_ENTRY() macro is designed to work for all of the subtables
>>      of the MADT.  In the ACPI 5.1 version of the spec, the struct for the
>>      GICC subtable (struct acpi_madt_generic_interrupt) 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.
>>
>>      This patch adds the BAD_MADT_GICC_ENTRY() that checks the GICC subtable
>>      only, accounting for the difference in specification versions that are
>>      possible.  The BAD_MADT_ENTRY() will continue to work as is for all other
>>      MADT subtables.
>>
>>      This code is being added to an arm64 header file since that is currently
>>      the only architecture using the GICC subtable of the MADT.  As a GIC is
>>      specific to ARM, it is also unlikely the subtable will be used elsewhere.
>>
>>      Fixes: aeb823bbacc2 ("ACPICA: ACPI 6.0: Add changes for FADT table.")
>>      Signed-off-by: Al Stone <al.stone@linaro.org>
>>      Acked-by: Will Deacon <will.deacon@arm.com>
>>      Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
>>      [catalin.marinas@arm.com: extra brackets around macro arguments]
>>      Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
>>
>> Signed-off-by: Julien Grall <julien.grall@arm.com>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> Signed-off-by: Julien Grall <jgrall@amazon.com>
> 
> Acked-by: Stefano Stabellini <sstabellini@kernel.org>

Thanks!

>> ---
>>
>> Changes in v2:
>>      - Patch added
>>
>> We may want to consider to also import:
>>
>> commit 9eb1c92b47c73249465d388eaa394fe436a3b489
>> Author: Jeremy Linton <jeremy.linton@arm.com>
>> Date:   Tue Nov 27 17:59:12 2018 +0000
> 
> Sure

I will add it in my todo list of further improvement.

Cheers,

-- 
Julien Grall