Re: [PATCH 16/17] arm64/nmi: Add Kconfig for NMI

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] ARM64_NMI enables architected NMI support but forgets to select HAVE_PERF_EVENTS_NMI, disabling the Perf Hardlockup Detector.
--

commit f760a575acac0e1b2376b42b4862ffcc32421ca9
Author: Mark Brown <broonie@kernel.org>

arm64/nmi: Add Kconfig for NMI
    
Since NMI handling is in some fairly hot paths we provide a Kconfig option
which allows support to be compiled out when not needed.

Link: https://lore.kernel.org/r/20221112151708.175147-14-broonie@kernel.org

> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index b3afe0688919b..218996752079e 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -2195,6 +2195,23 @@ endmenu # "ARMv8.7 architectural features"
>  config AS_HAS_MOPS
>  	def_bool $(as-instr,.arch_extension mops)
>  
> +menu "ARMv8.8 architectural features"
> +
> +config ARM64_NMI
> +	bool "Enable support for Non-maskable Interrupts (NMI)"

[Severity: Medium]
Does this configuration need to propagate its capability to the perf events
subsystem?

Currently, the main ARM64 configuration conditionally selects
HAVE_PERF_EVENTS_NMI when ARM64_PSEUDO_NMI is enabled:

arch/arm64/Kconfig:config ARM64
    ...
    select HAVE_PERF_EVENTS_NMI if ARM64_PSEUDO_NMI
    ...

Without similar treatment for ARM64_NMI, does the perf-based hardlockup
detector become silently unavailable when the system is configured to use
architected NMIs instead of pseudo-NMIs?

Should the ARM64 configuration be updated to select HAVE_PERF_EVENTS_NMI if
ARM64_NMI is also enabled?

> +	default y
> +	help
> +	  Non-maskable interrupts are an architecture and GIC feature
> +	  which allow the system to configure some interrupts to be
> +	  configured to have superpriority, allowing them to be handled
> +	  before other interrupts and masked for shorter periods of time.
> +
> +	  The feature is detected at runtime, and will remain disabled
> +	  if the cpu does not implement the feature. It will also be
> +	  disabled if pseudo NMIs are enabled at runtime.
> +
> +endmenu # "ARMv8.8 architectural features"

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260703100135.2512312-1-ruanjinjie@huawei.com?part=16