On Fri, Sep 7, 2018 at 4:28 PM Wei Wang <wei.w.wang@xxxxxxxxx> wrote:
> This patch adds support to KVM to save/restore the lbr stack on vCPU
> context switching.
>
> When the guest sets the ACTIVE bit of MSR_KVM_PV_LBR_CTRL, a perf event
> is created on the host for the related vCPU. This perf event ensures the
> LBR stack to be saved/restored when the vCPU thread is scheduled out/in.
> The perf event is removed and freed when the guest clears the ACTIVE
> bit.
[...]
> +void guest_lbr_event_release(struct kvm_pmu *pmu)
> +{
> + struct perf_event *event = pmu->guest_lbr_event;
> +
> + if (unlikely(!pmu->guest_lbr_event)) {
> + pr_err("%s: guest_lbr_event already freed\n", __func__);
> + return;
> + }
> +
> + if (event) {
> + event->pmu->stop(event, PERF_EF_UPDATE);
> + perf_event_release_kernel(event);
> + }
> + pmu->guest_lbr_event = NULL;
> +}
Is there some guarantee that this method will be called when the vCPU
is torn down on guest exit?
