linux-kernel - [PATCH v12 5/7] arm64: smp: IPI_CPU_STOP and IPI_CPU_CRASH

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Date:   Wed, 30 Aug 2023 12:11:26 -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,
        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>,
        Douglas Anderson <dianders@...omium.org>,
        D Scott Phillips <scott@...amperecomputing.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Valentin Schneider <vschneid@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v12 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>
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.

(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