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Date:   Mon, 07 Mar 2022 14:39:25 +0000
Message-ID: <877d9525eq.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     <catalin.marinas@arm.com>, <will@kernel.org>,
        Linu Cherian <lcherian@marvell.com>
Cc:     <tglx@linutronix.de>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <linuc.decode@gmail.com>
Subject: Re: [PATCH V3] irqchip/gic-v3: Workaround Marvell erratum 38545 when reading IAR
In-Reply-To: <20220307143014.22758-1-lcherian@marvell.com>
References: <20220307143014.22758-1-lcherian@marvell.com>
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On Mon, 07 Mar 2022 14:30:14 +0000,
Linu Cherian <lcherian@marvell.com> wrote:
> 
> When a IAR register read races with a GIC interrupt RELEASE event,
> GIC-CPU interface could wrongly return a valid INTID to the CPU
> for an interrupt that is already released(non activated) instead of 0x3ff.
> 
> As a side effect, an interrupt handler could run twice, once with
> interrupt priority and then with idle priority.
> 
> As a workaround, gic_read_iar is updated so that it will return a
> valid interrupt ID only if there is a change in the active priority list
> after the IAR read on all the affected Silicons.
> 
> Since there are silicon variants where both 23154 and 38545 are applicable,
> workaround for erratum 23154 has been extended to address both of them.
> 
> Signed-off-by: Linu Cherian <lcherian@marvell.com>
> ---
> Changes since V2:
> - Changed masked part number to individual part numbers
> - Added additional comment to clarify on priority groups
> 
> 
> Changes since V1:
> - IIDR based quirk management done for 23154 has been reverted
> - Extended existing 23154 errata to address 38545 as well,
>   so that existing static keys are reused. 
> - Added MIDR based support macros to cover all the affected parts
> - Changed the unlikely construct to likely construct in the workaround
>   function.
> 
> 
> 
> 
>  Documentation/arm64/silicon-errata.rst |  2 +-
>  arch/arm64/Kconfig                     |  8 ++++++--
>  arch/arm64/include/asm/arch_gicv3.h    | 23 +++++++++++++++++++++--
>  arch/arm64/include/asm/cputype.h       | 13 +++++++++++++
>  arch/arm64/kernel/cpu_errata.c         | 20 +++++++++++++++++---
>  5 files changed, 58 insertions(+), 8 deletions(-)

Looks good to me this time.

Catalin, Will: happy to take this into the irqchip tree for 5.18 with
your Ack, or you can take it into the arm64 tree with my

Reviewed-by: Marc Zyngier <maz@kernel.org>

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.