Re: [PATCH 26/38] arm64: nmi: Add handling of superpriority interrupts as NMIs

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

On 9/17/26 12:37, Jinjie Ruan wrote:
> 
> 在 2026/9/14 18:20, Vladimir Murzin 写道:
>> From: Mark Brown <broonie@kernel.org>
>>
>> Our goal with superpriority interrupts is to use them as NMIs, taking
>> advantage of the much smaller regions where they are masked to allow
>> prompt handling of the most time-critical interrupts.
>>
>> When an interrupt is configured with superpriority, we enter EL1 as we
>> do for any other interrupt. The presence of a superpriority interrupt
>> is indicated by a status bit in ISR_EL1. We check this bit before
>> unmasking interrupts in elX_interrupt(), and if a superpriority
>> interrupt is pending, we handle it as an NMI. Otherwise, normal
>> interrupts are handled as usual.
>>
>> Since superpriority interrupts are always handled as NMIs, the
>> interrupt controller can rely on in_nmi() to distinguish them from
>> ordinary interrupts.
>>
>> Enable IPIs to use superpriority interrupts as NMIs, matching the
>> existing pseudo-NMI behaviour.
>>
>> Signed-off-by: Mark Brown <broonie@kernel.org>
>> Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
>> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
>> Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>  arch/arm64/include/asm/entry-common.h |  7 +++
>>  arch/arm64/kernel/entry-common.c      | 83 +++++++++++++++++++++++----
>>  arch/arm64/kernel/smp.c               |  2 +-
>>  3 files changed, 79 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/entry-common.h b/arch/arm64/include/asm/entry-common.h
>> index 73d82a8d8e95..0681ba91ac3b 100644
>> --- a/arch/arm64/include/asm/entry-common.h
>> +++ b/arch/arm64/include/asm/entry-common.h
>> @@ -37,6 +37,13 @@ static inline bool arch_irqentry_exit_need_resched(void)
>>  	if (system_uses_irq_prio_masking() && read_sysreg(daif))
>>  		return false;
>>  
>> +	/*
>> +	 * If AllInt is set then we must have handled an NMI, so skip
>> +	 * preemption
>> +	 */
>> +	if (system_uses_nmi() && read_sysreg_s(SYS_ALLINT))
> if (system_uses_nmi() && (read_sysreg_s(SYS_ALLINT) & ALLINT_ALLINT))
> 

Ack.

Thanks
Vladimir