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Message-ID: <ZPBnkkDc9GSxrjmC@FVFF77S0Q05N>
Date: Thu, 31 Aug 2023 11:12:34 +0100
From: Mark Rutland <mark.rutland@....com>
To: Douglas Anderson <dianders@...omium.org>
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Sumit Garg <sumit.garg@...aro.org>,
Daniel Thompson <daniel.thompson@...aro.org>,
Marc Zyngier <maz@...nel.org>,
linux-arm-kernel@...ts.infradead.org,
Masayoshi Mizuma <msys.mizuma@...il.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
Chen-Yu Tsai <wens@...e.org>,
Lecopzer Chen <lecopzer.chen@...iatek.com>,
Tomohiro Misono <misono.tomohiro@...itsu.com>,
Stephane Eranian <eranian@...gle.com>,
kgdb-bugreport@...ts.sourceforge.net,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Stephen Boyd <swboyd@...omium.org>, ito-yuichi@...itsu.com,
linux-perf-users@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
D Scott Phillips <scott@...amperecomputing.com>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Valentin Schneider <vschneid@...hat.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v12 5/7] arm64: smp: IPI_CPU_STOP and IPI_CPU_CRASH_STOP
should try for NMI
On Wed, Aug 30, 2023 at 12:11:26PM -0700, Douglas Anderson wrote:
> There's no reason why IPI_CPU_STOP and IPI_CPU_CRASH_STOP can't be
> handled as NMI. They are very simple and everything in them is
> NMI-safe. Mark them as things to use NMI for if NMI is available.
>
> Suggested-by: Mark Rutland <mark.rutland@....com>
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>
> Reviewed-by: Misono Tomohiro <misono.tomohiro@...itsu.com>
> Reviewed-by: Sumit Garg <sumit.garg@...aro.org>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
> I don't actually have any good way to test/validate this patch. It's
> added to the series at Mark's request.
I've just sent out an LKDTM test that can be used to test this:
http://lore.kernel.org/lkml/20230831101026.3122590-1-mark.rutland@arm.com
So FWIW:
Acked-by: Mark Rutland <mark.rutland@....com>
Tested-by: Mark Rutland <mark.rutland@....com>
Mark.
>
> (no changes since v10)
>
> Changes in v10:
> - ("IPI_CPU_STOP and IPI_CPU_CRASH_STOP should try for NMI") new for v10.
>
> arch/arm64/kernel/smp.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 28c904ca499a..800c59cf9b64 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -946,6 +946,8 @@ static bool ipi_should_be_nmi(enum ipi_msg_type ipi)
> return false;
>
> switch (ipi) {
> + case IPI_CPU_STOP:
> + case IPI_CPU_CRASH_STOP:
> case IPI_CPU_BACKTRACE:
> return true;
> default:
> --
> 2.42.0.283.g2d96d420d3-goog
>
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