intel_idle: Add force_irq_on module param

For testing purposes.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.967699392@infradead.org

Author: Peter Zijlstra

drivers/idle/intel_idle.c

@@ -1837,6 +1837,9 @@ static bool __init intel_idle_verify_cstate(unsigned int mwait_hint)
 	return true;
 }
 
+static bool force_irq_on __read_mostly;
+module_param(force_irq_on, bool, 0444);
+
 static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv)
 {
 	int cstate;
@@ -1889,8 +1892,10 @@ static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv)
 		/* Structure copy. */
 		drv->states[drv->state_count] = cpuidle_state_table[cstate];
 
-		if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_IRQ_ENABLE)
+		if ((cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_IRQ_ENABLE) || force_irq_on) {
+			printk("intel_idle: forced intel_idle_irq for state %d\n", cstate);
 			drv->states[drv->state_count].enter = intel_idle_irq;
+		}
 
 		if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS) &&
 		    cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_IBRS) {