linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Julien Thierry <julien.thierry@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Andi Kleen <andi.kleen@intel.com>,
	Ashok Raj <ashok.raj@intel.com>, Borislav Petkov <bp@suse.de>,
	Tony Luck <tony.luck@intel.com>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	x86@kernel.org, sparclinux@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	Jacob Pan <jacob.jun.pan@intel.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Bartosz Golaszewski <brgl@bgdev.pl>,
	Doug Berger <opendmb@gmail.com>,
	Palmer Dabbelt <palmer@sifive.com>,
	iommu@lists.linux-foundation.org
Subject: Re: [RFC PATCH 03/23] genirq: Introduce IRQF_DELIVER_AS_NMI
Date: Thu, 14 Jun 2018 19:12:13 -0700	[thread overview]
Message-ID: <20180615021213.GC11625@voyager> (raw)
In-Reply-To: <c000699c-7859-74ec-7944-ec484e887f60@arm.com>

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

  reply	other threads:[~2018-06-15  2:15 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-13  0:57 [RFC PATCH 00/23] Implement an HPET-based hardlockup detector Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 01/23] x86/apic: Add a parameter for the APIC delivery mode Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 02/23] genirq: Introduce IRQD_DELIVER_AS_NMI Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 03/23] genirq: Introduce IRQF_DELIVER_AS_NMI Ricardo Neri
2018-06-13  8:34   ` Peter Zijlstra
2018-06-13  8:59     ` Julien Thierry
2018-06-13  9:20       ` Thomas Gleixner
2018-06-13  9:36         ` Julien Thierry
2018-06-13  9:49           ` Julien Thierry
2018-06-13  9:57           ` Thomas Gleixner
2018-06-13 10:25             ` Julien Thierry
2018-06-13 10:06         ` Marc Zyngier
2018-06-15  2:12           ` Ricardo Neri [this message]
2018-06-15  8:01             ` Julien Thierry
2018-06-16  0:39               ` Ricardo Neri
2018-06-16 13:36                 ` Thomas Gleixner
2018-06-13  0:57 ` [RFC PATCH 04/23] iommu/vt-d/irq_remapping: Add support for IRQCHIP_CAN_DELIVER_AS_NMI Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 05/23] x86/msi: " Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 06/23] x86/ioapic: Add support for IRQCHIP_CAN_DELIVER_AS_NMI with interrupt remapping Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 07/23] x86/hpet: Expose more functions to read and write registers Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 08/23] x86/hpet: Calculate ticks-per-second in a separate function Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 09/23] x86/hpet: Reserve timer for the HPET hardlockup detector Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 10/23] x86/hpet: Relocate flag definitions to a header file Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 11/23] x86/hpet: Configure the timer used by the hardlockup detector Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 12/23] kernel/watchdog: Introduce a struct for NMI watchdog operations Ricardo Neri
2018-06-13  7:41   ` Nicholas Piggin
2018-06-13  8:42     ` Peter Zijlstra
2018-06-13  9:26       ` Thomas Gleixner
2018-06-13 11:52         ` Nicholas Piggin
2018-06-14  1:31           ` Ricardo Neri
2018-06-14  2:32             ` Nicholas Piggin
2018-06-14  8:32               ` Thomas Gleixner
2018-06-15  2:21               ` Ricardo Neri
2018-06-14  1:26       ` Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 13/23] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 14/23] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2018-06-13  8:43   ` Peter Zijlstra
2018-06-14  1:19     ` Ricardo Neri
2018-06-14  1:41       ` Nicholas Piggin
2018-06-15  2:23         ` Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 15/23] kernel/watchdog: Add a function to obtain the watchdog_allowed_mask Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 16/23] watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2018-06-13  5:23   ` Randy Dunlap
2018-06-14  1:00     ` Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 17/23] watchdog/hardlockup/hpet: Convert the timer's interrupt to NMI Ricardo Neri
2018-06-13  9:07   ` Peter Zijlstra
2018-06-15  2:07     ` Ricardo Neri
2018-06-13  9:40   ` Thomas Gleixner
2018-06-15  2:03     ` Ricardo Neri
2018-06-15  9:19       ` Thomas Gleixner
2018-06-16  0:51         ` Ricardo Neri
2018-06-16 13:24           ` Thomas Gleixner
2018-06-20  0:15             ` Ricardo Neri
2018-06-20  0:25               ` Randy Dunlap
2018-06-21  0:25                 ` Ricardo Neri
2018-06-20  7:47               ` Thomas Gleixner
2018-06-13  0:57 ` [RFC PATCH 18/23] watchdog/hardlockup/hpet: Add the NMI watchdog operations Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 19/23] watchdog/hardlockup: Make arch_touch_nmi_watchdog() to hpet-based implementation Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 20/23] watchdog/hardlockup/hpet: Rotate interrupt among all monitored CPUs Ricardo Neri
2018-06-13  9:48   ` Thomas Gleixner
2018-06-15  2:16     ` Ricardo Neri
2018-06-15 10:29       ` Thomas Gleixner
2018-06-16  0:46         ` Ricardo Neri
2018-06-16 13:27           ` Thomas Gleixner
2018-06-13  0:57 ` [RFC PATCH 21/23] watchdog/hardlockup/hpet: Adjust timer expiration on the number of " Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 22/23] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Ricardo Neri
2018-06-13  5:26   ` Randy Dunlap
2018-06-14  0:58     ` Ricardo Neri
2018-06-14  3:30       ` Randy Dunlap
2018-06-13  0:57 ` [RFC PATCH 23/23] watchdog/hardlockup: Activate the HPET-based lockup detector Ricardo Neri

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180615021213.GC11625@voyager \
    --to=ricardo.neri-calderon@linux.intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=alexander.levin@verizon.com \
    --cc=andi.kleen@intel.com \
    --cc=ashok.raj@intel.com \
    --cc=bp@suse.de \
    --cc=brgl@bgdev.pl \
    --cc=daniel.lezcano@linaro.org \
    --cc=hpa@zytor.com \
    --cc=iommu@lists.linux-foundation.org \
    --cc=jacob.jun.pan@intel.com \
    --cc=julien.thierry@arm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=marc.zyngier@arm.com \
    --cc=mhiramat@kernel.org \
    --cc=mingo@kernel.org \
    --cc=opendmb@gmail.com \
    --cc=palmer@sifive.com \
    --cc=peterz@infradead.org \
    --cc=ravi.v.shankar@intel.com \
    --cc=rdunlap@infradead.org \
    --cc=sparclinux@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).