linux-kernel - [PATCH v13 5/7] arm64: smp: IPI_CPU_STOP and IPI_CPU_CRASH

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Message-ID: <20230906090246.v13.5.Ifadbfd45b22c52edcb499034dd4783d096343260@changeid>
Date:   Wed,  6 Sep 2023 09:03:00 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Mark Rutland <mark.rutland@....com>,
        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>
Cc:     linux-arm-kernel@...ts.infradead.org,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Lecopzer Chen <lecopzer.chen@...iatek.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Tomohiro Misono <misono.tomohiro@...itsu.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Masayoshi Mizuma <msys.mizuma@...il.com>,
        Stephane Eranian <eranian@...gle.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        kgdb-bugreport@...ts.sourceforge.net,
        Stephen Boyd <swboyd@...omium.org>,
        linux-perf-users@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>, ito-yuichi@...itsu.com,
        Douglas Anderson <dianders@...omium.org>,
        Chen-Yu Tsai <wenst@...omium.org>, jpoimboe@...nel.org,
        linux-kernel@...r.kernel.org, scott@...amperecomputing.com,
        vschneid@...hat.com
Subject: [PATCH v13 5/7] arm64: smp: IPI_CPU_STOP and IPI_CPU_CRASH_STOP should try for NMI

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>
Acked-by: Mark Rutland <mark.rutland@....com>
Tested-by: Mark Rutland <mark.rutland@....com>
Tested-by: Chen-Yu Tsai <wenst@...omium.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---
This patch is tested by Mark Rutland's LKDTM test [1].

[1] http://lore.kernel.org/lkml/20230831101026.3122590-1-mark.rutland@arm.com

(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