linux-kernel - Re: [RFC PATCH 1/5] KVM: vmx: speed up emulation of invalid guest state

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Message-ID: <5355E145.9000406@redhat.com>
Date:	Mon, 21 Apr 2014 23:25:57 -0400
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>
CC:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [RFC PATCH 1/5] KVM: vmx: speed up emulation of invalid guest
 state

Il 20/04/2014 22:13, Marcelo Tosatti ha scritto:
> The same code which resets it to false inside the
> handle_invalid_guest_state loop (so you would stop emulating
> at the same point as you do with this patch).

So (barring any bugs where we fail to set vmx->emulation_required to 
true) the "vmx->emulation_required = true;" on vmentry error would be 
dead code.

> Advantage would be that failure to set vmx->emulation_required to
> true would not cause VM-entry failure.

A place where we fail to set vmx->emulation_required to true is quite 
likely to also be wrong when setting vmx->emulation_required to false. 
Since this is not something that has ever seen much churn, I think it's 
better to code it in a way that shows bugs easily.  The bugs do not 
affect the host anyway.

Paolo
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