Re: [kvm-unit-tests patch v6 17/18] x86: pmu: Adjust lower boundary of branch-misses event

[Sean Christopherson]

On Sat, Sep 14, 2024, Dapeng Mi wrote:
> @@ -205,6 +208,17 @@ static void adjust_events_range(struct pmu_event *gp_events,
>  		gp_events[branch_idx].min = LOOP_BRANCHES;
>  		gp_events[branch_idx].max = LOOP_BRANCHES;
>  	}
> +
> +	/*
> +	 * For CPUs without IBPB support, no way to force to trigger a
> +	 * branch miss and the measured branch misses is possible to be
> +	 * 0. Thus overwrite the lower boundary of branch misses event
> +	 * to 0 to avoid false positive.
> +	 */
> +	if (!has_ibpb()) {
> +		/* branch misses event */

This comment is worse than useless, because it necessitates curly braces.

> +		gp_events[branch_miss_idx].min = 0;
> +	}
>  }