On Mon, 21 Mar, at 02:53:04AM, tip-bot for Vikas Shivappa wrote:
> @@ -489,6 +496,22 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group, u32 rmid)
>
> raw_spin_unlock_irq(&cache_lock);
>
> + /*
> + * If the allocation is for mbm, init the mbm stats.
> + * Need to check if each event in the group is mbm event
> + * because there could be multiple type of events in the same group.
> + */
> + if (__rmid_valid(rmid)) {
> + event = group;
> + if (is_mbm_event(event->attr.config))
> + init_mbm_sample(rmid, event->attr.config);
> +
> + list_for_each_entry(event, head, hw.cqm_group_entry) {
> + if (is_mbm_event(event->attr.config))
> + init_mbm_sample(rmid, event->attr.config);
> + }
> + }
> +
> return old_rmid;
> }
>
You're calling init_mbm_sample() without holding cache_lock. Won't
this potentially trash the existing value in MSR_IA32_QM_EVTSEL, if
say, we're reading the counter at the same time as the recycling
worker is running?
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