--- zzzz-none-000/linux-3.10.107/arch/x86/kernel/cpu/perf_event_knc.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/x86/kernel/cpu/perf_event_knc.c	2021-02-04 17:41:59.000000000 +0000
@@ -217,7 +217,7 @@
 	int bit, loops;
 	u64 status;
 
-	cpuc = &__get_cpu_var(cpu_hw_events);
+	cpuc = this_cpu_ptr(&cpu_hw_events);
 
 	knc_pmu_disable_all();
 
@@ -263,7 +263,9 @@
 		goto again;
 
 done:
-	knc_pmu_enable_all(0);
+	/* Only restore PMU state when it's active. See x86_pmu_disable(). */
+	if (cpuc->enabled)
+		knc_pmu_enable_all(0);
 
 	return handled;
 }