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

From: Wei Wang
Date: Thu Jan 03 2019 - 02:17:03 EST

On 01/03/2019 07:26 AM, Jim Mattson wrote:
On Wed, Dec 26, 2018 at 2:01 AM Wei Wang <> 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
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.