Re: [RFC PATCH 29/36] arm64: nmi: Manage masking for superpriority interrupts

[Vladimir Murzin <vladimir.murzin@arm.com>]

On 7/10/26 11:08, Jinjie Ruan wrote:
>> diff --git a/arch/arm64/include/asm/interrupts/common_flags.h b/arch/arm64/include/asm/interrupts/common_flags.h
>> index 72ed6e75d146..315aaec3ea34 100644
>> --- a/arch/arm64/include/asm/interrupts/common_flags.h
>> +++ b/arch/arm64/include/asm/interrupts/common_flags.h
>> @@ -20,6 +20,14 @@
>>  /*
>>   * Exception context mapping
>>   *
>> + * FEAT_NMI
>> + *
>> + * CRITICAL -> DAIF + AllInt (corresponds to the state on exception entry)
>> + * ERROR    ->  AIF + AllInt
>> + * NONMI    ->   IF + AllInt
>> + * NOIRQ    ->   IF
>> + * PROCESS  ->    0
>> + *
>>   * pseudo-NMI
>>   *
>>   * CRITICAL -> DAIF + IRQON  (corresponds to the state on exception entry)
>> @@ -76,6 +84,7 @@ arm64_exc_hwstate_t __arm64_exc_hwstate_of_noirq_context(void)
>>  		return (arm64_exc_hwstate_t){.daif=DAIF_PROCCTX, .pmr=GIC_PRIO_IRQOFF};
>>  
>>  	return (arm64_exc_hwstate_t){.daif=DAIF_PROCCTX_NOIRQ};
>> +
>>  }
>>  
>>  static __always_inline
>> @@ -84,6 +93,9 @@ arm64_exc_hwstate_t __arm64_exc_hwstate_of_nonmi_context(void)
>>  	if (system_uses_irq_prio_masking())
>>  		return (arm64_exc_hwstate_t){.daif=DAIF_PROCCTX_NOIRQ, .pmr=GIC_PRIO_IRQON};
>>  
>> +	if (system_uses_nmi())
>> +               return (arm64_exc_hwstate_t){.daif=DAIF_PROCCTX_NOIRQ, .allint=ALLINT_ALLINT};
>> +
>>  	return (arm64_exc_hwstate_t){.daif=DAIF_PROCCTX_NOIRQ};
> 
> DAIF_PROCCTX_NOIRQ is universal; can it be initialized with a loal
> varible and set at the beginning?
> 
> 90 static __always_inline
>  91 arm64_exc_hwstate_t __arm64_exc_hwstate_of_nonmi_context(void)
>  92 {
>  93 >-------arm64_exc_hwstate_t state = { .daif=DAIF_PROCCTX_NOIRQ };
>  94
>  95 >-------if (system_uses_irq_prio_masking())
>  96 >------->-------state.pmr = GIC_PRIO_IRQON;
>  97
>  98 >-------if (system_uses_nmi())
>  99 >------->-------state.allint = ALLINT_ALLINT;
> 100
> 101 >-------return state;
> 102 }

It can be, but I did it this way because it can be quickly and easily
matched with the exception context mapping documented at the top of
the file. I don't have a strong opinion - if others find a different
approach more helpful, I'm happy to change it.

Cheers
Vladimir