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Date: Wed, 07 May 2014 13:37:14 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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To: Abel Gordon <abel@stratoscale.com>
CC: Hu Yaohui <loki2441@gmail.com>, Bandan Das <bsd@redhat.com>,
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        Muli Ben-Yehuda <muli@stratoscale.com>
Subject: Re: KVM Nested L2 guest startup problems
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Il 07/05/2014 13:16, Abel Gordon ha scritto:
>> > PLE should be left enabled, I think.
> Well... the PLE settings L0 uses to run  L1 (vmcs01) may be different
> than the PLE settings L1 configured to run  L2 (vmcs12).
> For example, L0 can use a  ple_gap to run L1 that is bigger than the
> ple_gap L1 configured to run L2. Or  L0 can use a ple_window to run L1
> that is smaller than the ple_window L1 configured to run L2.

That's correct.  We should leave PLE enabled while running L2, but hide 
the feature altogether from L1.

Paolo

> So seems PLE should never be exposed to L1 or an appropriate nested
> handling needs to be implemented. Note the handling may become complex
> because in some cases a PLE exit from L2 should be handled directly by
> L0 and not passed to L1... remember nested preemption timer support :)
> ?