[RFC PATCH 31/36] arm64: nmi: Add handling of superpriority interrupts as NMIs

[Vladimir Murzin]

On 7/15/26 13:07, Jinjie Ruan wrote:
>> FEAT_NMI
>>
>>   We can distinguish between an NMI and an IRQ on exception
>>   entry. Thus, for an IRQ, we can immediately drop to NOIRQ_CONTEXT
>>   before passing control to the IRQ handler, allowing NMIs to preempt
>>   the IRQ handler. This corresponds to case 2 of the pNMI flow above.
>>
> I think this is not quite correct. When entering the __el1_irq()
> function, if only system_uses_nmi() is true, it does not necessarily
> mean it is NOIRQ_CONTEXT.
> 
> I believe the unmasking of allint, or NOIRQ_CONTEXT, should be delayed
> until gic_handle_irq() actually before we processes the interrupt as
> gic_unmask_pnmis() do it. At this point, it is still NONMI_CONTEXT to
> keep  hardware NMI masked as isr_el1.IS is not set.

It looks like your LLM needs the additional context from the
"[RFC PATCH 36/36] irqchip/gic-v3: Implement FEAT_GICv3_NMI support".

With that context, it should recognise that NMIs and IRQs take
separate handling paths and use separate hardware state, so they do
not interfere with each other. As a result, IRQ handling only needs to
mask IRQs. In other words, there is no need to delay entering
NOIRQ_CONTEXT until reaching the GIC.

Cheers
Vladimir