Message-ID: <4C10569E.6020503@redhat.com>
Date: Thu, 10 Jun 2010 06:06:06 +0300
From: Avi Kivity <avi@redhat.com>
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To: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
CC: LKML <linux-kernel@vger.kernel.org>, kvm@vger.kernel.org,
       Ingo Molnar <mingo@elte.hu>, Fr??d??ric Weisbecker <fweisbec@gmail.com>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Cyrill Gorcunov <gorcunov@gmail.com>, Lin Ming <ming.m.lin@intel.com>,
       Sheng Yang <sheng@linux.intel.com>,
       Marcelo Tosatti <mtosatti@redhat.com>, oerg Roedel <joro@8bytes.org>,
       Jes Sorensen <Jes.Sorensen@redhat.com>, Gleb Natapov <gleb@redhat.com>,
       Zachary Amsden <zamsden@redhat.com>, zhiteng.huang@intel.com,
       tim.c.chen@intel.com, Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [RFC] para virt interface of perf to support kvm guest os statistics
 collection in guest os
References: <1276054214.2096.383.camel@ymzhang.sh.intel.com>	 <4C0F51DD.3080200@redhat.com>	 <1276075280.2096.427.camel@ymzhang.sh.intel.com>	 <4C0F61D3.9000402@redhat.com> <1276136493.2096.462.camel@ymzhang.sh.intel.com>
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On 06/10/2010 05:21 AM, Zhang, Yanmin wrote:
>
>> I see.  So put it in a union.  Or perhaps not even in a union - what if
>> a kvm guest is also acting as a kvm host?
>>      
> My patch has consideration on it. I compiled kernel with host and guest support
> at the same time. The accessing to perf_event->shadow is really under specific
> scenarios, or they are just in specific functions. These functions are called
> just bu host kernel , or just by guest kernel.
>    

But a kernel can be both guest and host at the same time.  Currently 
this only works on AMD, but there was some work to bring it to Intel as 
well.


-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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