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Date: Wed, 30 May 2018 10:55:06 +0200
From: Peter Zijlstra <peterz@infradead.org>
Subject: [MODERATED] Re: [PATCH 1/2] L1TF KVM 1
Message-ID: <20180530085506.GH12217@hirez.programming.kicks-ass.net>
References: <20180529194214.2600-1-pbonzini@redhat.com>
 <20180529194240.7F1336110A@crypto-ml.lab.linutronix.de>
 <alpine.DEB.2.21.1805292350200.1597@nanos.tec.linutronix.de>
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On Wed, May 30, 2018 at 12:49:55AM +0200, speck for Thomas Gleixner wrote:
> > +	case EXIT_REASON_EXTERNAL_INTERRUPT: {
> > +		int cpu = raw_smp_processor_id();
> > +		int vector = per_cpu(last_vector, cpu);
> > +		return vector == LOCAL_TIMER_VECTOR || vector == RESCHEDULE_VECTOR;
> 
> That wants a comment why these two are considered safe.
> 
> The timer vector is a doubtful one. It does not necessarily cause a
> reschedule and it can run arbitrary softirq code on interrupt return. I
> wouldn't be that sure that it's safe.

reschedule can also cause softirq to run.

And there's just no way we can guarantee softirq doesn't do something
sensitive, like IPsec processing or whatever.