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

Hi Stefano,

On 24/10/2020 01:32, Stefano Stabellini wrote:
On Fri, 23 Oct 2020, Julien Grall wrote:
From: Julien Grall <julien.grall@xxxxxxx>

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@xxxxxxxxxx>
     Acked-by: Will Deacon <will.deacon@xxxxxxx>
     Acked-by: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
     [catalin.marinas@xxxxxxx: extra brackets around macro arguments]
     Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>



Changes in v2:
     - Patch added

We may want to consider to also import:

commit 9eb1c92b47c73249465d388eaa394fe436a3b489
Author: Jeremy Linton <jeremy.linton@xxxxxxx>
Date:   Tue Nov 27 17:59:12 2018 +0000


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


Julien Grall



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