Re: [PATCH v4 04/10] KVM/x86: intel_pmu_lbr_enable

[Wei Wang]

On 01/03/2019 07:26 AM, Jim Mattson wrote:
> On Wed, Dec 26, 2018 at 2:01 AM Wei Wang <wei.w.wang@xxxxxxxxx> wrote:
> > The lbr stack is architecturally specific, for example, SKX has 32 lbr
> > stack entries while HSW has 16 entries, so a HSW guest running on a SKX
> > machine may not get accurate perf results. Currently, we forbid the
> > guest lbr enabling when the guest and host see different lbr stack
> > entries.
> How do you handle live migration?

This feature is gated by the QEMU "lbr=true" option.
So if the lbr fails to work on the destination machine,
the destination side QEMU wouldn't be able to boot,
and migration will not happen.

Best,
Wei