linux-kernel - Re: [PATCH 0/2] Fix dmar fault interrupt problems

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Message-ID: <20101130192845.GI10050@sequoia.sous-sol.org>
Date:	Tue, 30 Nov 2010 11:28:45 -0800
From:	Chris Wright <chrisw@...s-sol.org>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	Chris Wright <chrisw@...s-sol.org>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"indou.takao@...fujitsu.com" <indou.takao@...fujitsu.com>
Subject: Re: [PATCH 0/2] Fix dmar fault interrupt problems

* Suresh Siddha (suresh.b.siddha@...el.com) wrote:
> On Tue, 2010-11-30 at 10:13 -0800, Chris Wright wrote:
> > * Suresh Siddha (suresh.b.siddha@...el.com) wrote:
> > > On Tue, 2010-11-30 at 00:28 -0800, Kenji Kaneshige wrote:
> > > > Hi,
> > > > 
> > > > Here are patches to fix the following problems regarding dmar fault interrupt.
> > > > 
> > > > - No dmar fault event is notified in x2apic cluster mode
> > > > - Changing IRQ affinity of dmar fault interrupt causes "No irq handler
> > > >   for vector (irq XX)" message and dmar fault interrupts are never
> > > >   notified after that.
> > > 
> > > Kenji, In addition to these two, there are couple of more patches that
> > > are needed to fix the kexec/kdump issue that we are debugging on RH
> > > bugzilla.
> > > 
> > > I will post all these 4 patches shortly. I already noticed and queued
> > > the second patch (dmar irq migration)  you mentioned.
> > 
> > And one of them (the additional call to flushing existing dmar faults)
> > is not needed.
> 
> yes, that patch is not needed for the current kexec/kdump issue. But
> nevertheless that is an issue that needs to be addressed aswell.

AFAICT, it just becomes a duplicate call in a narrow window.

native_smp_prepare_cpus() (or APIC_init_uniprocessor()):
 enable_IR_x2apic()
  enable_IR()
   enable_intr_remapping() <-- clears faults
 default_setup_apic_routing()
   enable_drhd_fault_handling() <-- added call to clear faults

That's what I meant by not needed.

thanks,
-chris
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