From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: perf uncore & lkvm woes Date: Thu, 16 Aug 2012 14:06:44 +0300 Message-ID: <502CD444.5020807@redhat.com> References: <1345101585.31459.112.camel@twins> <502CA368.8050404@linux.intel.com> <502CB1F6.4010204@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Yan, Zheng" , Peter Zijlstra , Sasha Levin , Asias He , Cyrill Gorcunov , Ingo Molnar , KVM General , Gleb Natapov To: Pekka Enberg Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34193 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750999Ab2HPLHC (ORCPT ); Thu, 16 Aug 2012 07:07:02 -0400 In-Reply-To: <502CB1F6.4010204@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/16/2012 11:40 AM, Avi Kivity wrote: > On 08/16/2012 10:41 AM, Pekka Enberg wrote: >> On 08/16/2012 03:19 PM, Peter Zijlstra wrote: >>>> On Thu, 2012-08-16 at 10:01 +0300, Pekka Enberg wrote: >>>>> Has anyone seen this? It's kvmtool/next with 3.6.0-rc1. Looks like we >>>>> are doing uncore_init() on virtualized CPU which breaks boot. >>>> >>>> I think you're the first.. I don't normally use kvm if I can at all >>>> avoid it. >>>> >>>> But I think its a 'simple' matter of kvm not emulating the entire >>>> hardware. Afaik the uncore isn't enumerated and we simply assume MSR >>>> presence based on cpu model. >> >> On Thu, Aug 16, 2012 at 10:38 AM, Yan, Zheng >> wrote: >>> The Intel uncore doc does not specify how to check if uncore exist. >>> How about disabling uncore on virtualized CPU? >> >> (CC'ing Avi.) >> > > Seems reasonable, if unfortunate. It's pretty easy to check for. > > If those are separate MSRs, we can also trap the #GP and exit gracefully. Another option is to deal with them on the host side. That has the benefit of working with non-Linux guests too. We can just ignore the MSR and print some warning. -- error compiling committee.c: too many arguments to function