perf/x86/vlbr: Add c->flags to vlbr event constraints

Just like what we do in the x86_get_event_constraints(), the
PERF_X86_EVENT_LBR_SELECT flag should also be propagated
to event->hw.flags so that the host lbr driver can save/restore
MSR_LBR_SELECT for the special vlbr event created by KVM or BPF.

Fixes: 097e431 ("perf/x86: Add constraint to create guest LBR event without hw counter")
Reported-by: Wanpeng Li <[email protected]>
Signed-off-by: Like Xu <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Tested-by: Wanpeng Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Like Xu

arch/x86/events/intel/core.c

@@ -3048,8 +3048,10 @@ intel_vlbr_constraints(struct perf_event *event)
 {
 	struct event_constraint *c = &vlbr_constraint;
 
-	if (unlikely(constraint_match(c, event->hw.config)))
+	if (unlikely(constraint_match(c, event->hw.config))) {
+		event->hw.flags |= c->flags;
 		return c;
+	}
 
 	return NULL;
 }