From: Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v1 0/4] Enable LBR for the guest
Date: Mon, 25 Sep 2017 07:59:08 -0700
Message-ID: <20170925145908.GN4311@tassilo.jf.intel.com>
References: <1506314696-4632-1-git-send-email-wei.w.wang@intel.com>
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Cc: virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, pbonzini@redhat.com, mst@redhat.com,
        rkrcmar@redhat.com, mingo@redhat.com
To: Wei Wang <wei.w.wang@intel.com>
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On Mon, Sep 25, 2017 at 12:44:52PM +0800, Wei Wang wrote:
> This patch series enables the Last Branch Recording feature for the
> guest. Instead of trapping each LBR stack MSR access, the MSRs are
> passthroughed to the guest. Those MSRs are switched (i.e. load and
> saved) on VMExit and VMEntry.
> 
> Test:
> Try "perf record -b ./test_program" on guest.

I don't see where you expose the PERF capabilities MSR? 

That's normally needed for LBR too to report the version
number.

-Andi