From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH] kvm-vmx: add module parameter to avoid trapping HLT
	instructions (v3)
Date: Sat, 4 Dec 2010 00:32:31 +0100
Message-ID: <20101203233231.GA29502@8bytes.org>
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Cc: kvm@vger.kernel.org, Avi Kivity <avi@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Chris Wright <chrisw@sous-sol.org>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
To: Anthony Liguori <aliguori@us.ibm.com>
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On Fri, Dec 03, 2010 at 04:39:22PM -0600, Anthony Liguori wrote:
> +	if (yield_on_hlt)
> +		min |= CPU_BASED_HLT_EXITING;

This approach won't work out on AMD because in HLT the CPU may enter
C1e. In C1e the local apic timer interupt is not delivered anymore and
when this is the current timer in use the cpu may miss timer ticks or
never comes out of HLT again. The guest has no chance to work around
this as the Linux idle routine does. 
If you really wan't active idling of a guest, it should idle in the
hypervisor where it can work around such problems.

	Joerg