diff mbox series

[v12,5/7] arm64: smp: IPI_CPU_STOP and IPI_CPU_CRASH_STOP should try for NMI

Message ID 20230830121115.v12.5.Ifadbfd45b22c52edcb499034dd4783d096343260@changeid (mailing list archive)
State New, archived
Headers show
Series arm64: Add IPI for backtraces / kgdb; try to use NMI for some IPIs | expand

Commit Message

Doug Anderson Aug. 30, 2023, 7:11 p.m. UTC
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@arm.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Misono Tomohiro <misono.tomohiro@fujitsu.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.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(+)

Comments

Mark Rutland Aug. 31, 2023, 10:12 a.m. UTC | #1
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@arm.com>
> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
> Reviewed-by: Misono Tomohiro <misono.tomohiro@fujitsu.com>
> Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
> Signed-off-by: Douglas Anderson <dianders@chromium.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@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.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
>
diff mbox series

Patch

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: