Re: [RFC PATCH v2 00/45] arm64: Add support for FEAT_NMI

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

On 8/14/26 02:52, Jinjie Ruan wrote:
> 
> 在 2026/7/28 0:34, Vladimir Murzin 写道:
>> FEAT_NMI provides an architected mechanism for supporting non-maskable
>> interrupts (NMIs) and less-masked interrupts (LMIs).
>>
>> Since we already support pseudo-NMIs via priority masking, introducing
>> another flavour of NMI on top of the existing infrastructure could
>> easily become messy, making the code harder to follow and reason
>> about.
>>
>> To avoid that, this series first makes room for the new NMI "tenant"
>> by restructuring the existing exception masking logic.
>>
>> The main idea is to separate the logical view of exception state from
>> its hardware representation. To achieve this, we introduce logical
>> exception contexts that can be mapped onto the corresponding hardware
>> state. This naturally consolidates the hardware-specific handling into
>> a small number of places, while allowing the rest of the code to
>> operate purely in terms of logical exception contexts.
>>
>> Since this restructuring is non-trivial and carries a risk of subtle
>> behavioural changes, the series adds extensive debug checks to verify
>> that the hardware state always matches the expected logical state.
>>
>> With this restructuring in place, wiring FEAT_NMI into the new
>> framework becomes much more manageable.
>>
>> This work would not have been possible without the contributions of
>> Ada Couprie Diaz, Mark Brown, and Lorenzo Pieralisi - please credit
>> them for everything that works well. Any remaining bugs or issues are
>> entirely my own.
>>
>> I'd especially appreciate feedback on the overall approach. Please
>> don't hesitate to bikeshed the naming or other details - improving
>> clarity is one of the main goals of this series. Of course, technical
>> review is more than welcome as well.
>>
>> The series would also benefit from extensive testing on real hardware
>> (without NMI, with pseudo-NMI, and with FEAT_NMI), as most of the
>> testing so far has been done on QEMU and Fast Model.
> Hi all,
> 
> Apart from gicv5, I have gone through the other patches. Apart from code
> style issues, patch split and certain specific implementation details, I
> don't see any major issues. I am very much looking forward to more
> reviews, discussions, and the next version.
> 

Thanks Jinjie! I really appreciate you taking the time to go through the series.

Cheers
Vladimir

> Best regards,
> Jinjie
>