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    SubjectRe: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on
    On Wed, Feb 15, 2017 at 03:05:10PM +0200, Alexander Shishkin wrote:
    > Peter Zijlstra <peterz@infradead.org> writes:
    >
    > > On Wed, Feb 15, 2017 at 10:34:58AM +0200, Alexander Shishkin wrote:
    > >
    > >> Well, we can't make the limitation go away. You'll still have to stop
    > >> kvms to get any 'meaningful' PT data.
    > >
    > > Why would you need to stop all VMs in order to get your !VM data? Sure,
    > > you get black holes where the VM runs, but we should be able to see
    > > everything else.
    >
    > No, what I mean is that if you run kvm prior to starting perf record,
    > which I assume is the case for acme, your entire session is a black
    > hole. The VMXON happens pretty early on, you can open /dev/kvm,
    > ioctl(KVM_CREATE_VM) on it and that will do a VMXON already.

    kvm_intel has a vmm_exclusive parameter, if you set that to 0 is
    _should_ behave much better.

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