From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH] kvm-vmx: add module parameter to avoid trapping HLT instructions (v2) Date: Mon, 06 Dec 2010 08:08:08 -0600 Message-ID: <4CFCEE48.1050206@codemonkey.ws> References: <1291298357-5695-1-git-send-email-aliguori@us.ibm.com> <20101202173733.GA26342@amt.cnet> <4CF7EE63.40209@codemonkey.ws> <20101202201223.GA31316@amt.cnet> <4CF806E7.1090404@codemonkey.ws> <4CF8BA34.1000508@redhat.com> <4CF9730C.7040904@codemonkey.ws> <4CF9F83C.5040807@redhat.com> <4CFA425D.3010100@codemonkey.ws> <4CFC9EC6.3010108@redhat.com> <4CFCA06B.9030406@redhat.com> <4CFCEBE9.2010107@codemonkey.ws> <4CFCECA6.3030007@redhat.com> <4CFCECEF.3090905@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, Chris Wright , Srivatsa Vaddagiri To: Avi Kivity Return-path: Received: from mail-gw0-f42.google.com ([74.125.83.42]:47629 "EHLO mail-gw0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752968Ab0LFOIL (ORCPT ); Mon, 6 Dec 2010 09:08:11 -0500 Received: by gwb20 with SMTP id 20so6488935gwb.1 for ; Mon, 06 Dec 2010 06:08:11 -0800 (PST) In-Reply-To: <4CFCECEF.3090905@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: 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. Regards, Anthony Liguori