On Wed, Jun 13, 2018 at 11:06:25AM +0100, Marc Zyngier wrote: > On 13/06/18 10:20, Thomas Gleixner wrote: > > On Wed, 13 Jun 2018, Julien Thierry wrote: > >> On 13/06/18 09:34, Peter Zijlstra wrote: > >>> On Tue, Jun 12, 2018 at 05:57:23PM -0700, Ricardo Neri wrote: > >>>> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h > >>>> index 5426627..dbc5e02 100644 > >>>> --- a/include/linux/interrupt.h > >>>> +++ b/include/linux/interrupt.h > >>>> @@ -61,6 +61,8 @@ > >>>> * interrupt handler after suspending interrupts. For > >>>> system > >>>> * wakeup devices users need to implement wakeup > >>>> detection in > >>>> * their interrupt handlers. > >>>> + * IRQF_DELIVER_AS_NMI - Configure interrupt to be delivered as > >>>> non-maskable, if > >>>> + * supported by the chip. > >>>> */ > >>> > >>> NAK on the first 6 patches. You really _REALLY_ don't want to expose > >>> NMIs to this level. > >>> > >> > >> I've been working on something similar on arm64 side, and effectively the one > >> thing that might be common to arm64 and intel is the interface to set an > >> interrupt as NMI. So I guess it would be nice to agree on the right approach > >> for this. > >> > >> The way I did it was by introducing a new irq_state and let the irqchip driver > >> handle most of the work (if it supports that state): > >> > >> https://lkml.org/lkml/2018/5/25/181 > >> > >> This has not been ACKed nor NAKed. So I am just asking whether this is a more > >> suitable approach, and if not, is there any suggestions on how to do this? > > > > I really didn't pay attention to that as it's burried in the GIC/ARM series > > which is usually Marc's playground. > > I'm working my way through it ATM now that I have some brain cycles back. > > > Adding NMI delivery support at low level architecture irq chip level is > > perfectly fine, but the exposure of that needs to be restricted very > > much. Adding it to the generic interrupt control interfaces is not going to > > happen. That's doomed to begin with and a complete abuse of the interface > > as the handler can not ever be used for that. > > I can only agree with that. Allowing random driver to use request_irq() > to make anything an NMI ultimately turns it into a complete mess ("hey, > NMI is *faster*, let's use that"), and a potential source of horrible > deadlocks. > > What I'd find more palatable is a way for an irqchip to be able to > prioritize some interrupts based on a set of architecturally-defined > requirements, and a separate NMI requesting/handling framework that is > separate from the IRQ API, as the overall requirements are likely to > completely different. > > It shouldn't have to be nearly as complex as the IRQ API, and require > much stricter requirements in terms of what you can do there (flow > handling should definitely be different). Marc, Julien, do you plan to actively work on this? Would you mind keeping me in the loop? I also need this work for this watchdog. In the meantime, I will go through Julien's patches and try to adapt it to my work. Thanks and BR, Ricardo -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
