From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH] kvm-vmx: add module parameter to avoid trapping HLT
 instructions (v2)
Date: Mon, 6 Dec 2010 16:14:49 +0200
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Cc: Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>,
	kvm@vger.kernel.org, Chris Wright <chrisw@sous-sol.org>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
To: Anthony Liguori <anthony@codemonkey.ws>
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On Mon, Dec 06, 2010 at 08:08:08AM -0600, Anthony Liguori wrote:
> On 12/06/2010 08:02 AM, Avi Kivity wrote:
> >On 12/06/2010 04:01 PM, Avi Kivity wrote:
> >>>It's not just possible, it appears to be exactly what happens.
> >>>
> >>>I guess it makes sense that RIP gets advanced before HLT
> >>>begins to wait.
> >>>
> >>
> >>
> >>It does.  Good, it simplifies the patch.
> >>
> >
> >btw, this is how kvm emulates HLT - first we advance rip, then we
> >sleep the vcpu.
> 
> Yes, I assume the hardware updates RIP immediately after fetching
> the instruction.  That's at least how some simpler architectures I'm
> aware of work.
> 
By "simpler" you mean "saner"? x86 needs at least decode it before
updating RIP :)
 
--
			Gleb.