From mboxrd@z Thu Jan  1 00:00:00 1970
From: Don Zickus <dzickus@redhat.com>
Subject: Re: [PATCH 08/13] xen/pvticketlock: disable interrupts while blocking
Date: Tue, 13 Sep 2011 15:27:06 -0400
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To: Andi Kleen <andi@firstfloor.org>
Cc: Avi Kivity <avi@redhat.com>, Jeremy Fitzhardinge <jeremy@goop.org>, Peter Zijlstra <peterz@infradead.org>, "H. Peter Anvin" <hpa@zytor.com>, Linus Torvalds <torvalds@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>, the arch/x86 maintainers <x86@kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Nick Piggin <npiggin@kernel.dk>, Marcelo Tosatti <mtosatti@redhat.com>, KVM <kvm@vger.kernel.org>, Xen Devel <xen-devel@lists.xensource.com>, Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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On Tue, Sep 13, 2011 at 09:03:20PM +0200, Andi Kleen wrote:
> > So I got around to implementing this and it seems to work great.  The back
> > to back NMIs are detected properly using the %rip and that info is passed to
> > the NMI notifier.  That info is used to determine if only the first
> > handler to report 'handled' is executed or _all_ the handlers are
> > executed.
> > 
> > I think all the 'unknown' NMIs I generated with various perf runs have
> > disappeared.  I'll post a new version of my nmi notifier rewrite soon.
> 
> This will fail when the system is idle.

Oh one other thing I forgot to mention is that an NMI handler has to
return a value greater than 1, meaning that it handle multiple NMI events
during this NMI to even enable the 'NMI swallowing' algorithm.

Cheers,
Don