Re: [tip: x86/fpu] intel_idle: Add a new flag to initialize the AMX state

[Peter Zijlstra <peterz@infradead.org>]

On Wed, Jun 08, 2022 at 07:32:37PM -0000, tip-bot2 for Chang S. Bae wrote:
> @@ -134,6 +140,9 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
>  	if (state->flags & CPUIDLE_FLAG_IRQ_ENABLE)
>  		local_irq_enable();
>  
> +	if (state->flags & CPUIDLE_FLAG_INIT_XSTATE)
> +		fpu_idle_fpregs();
> +
>  	mwait_idle_with_hints(eax, ecx);
>  
>  	return index;

This will conflict with an intel_idle patch Rafael took from me; the
resolution would be something along these lines:

--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -166,6 +166,13 @@ static __cpuidle int intel_idle_irq(stru
 	return ret;
 }
 
+static __cpuidle int intel_idle_xstate(struct cpuidle_device *dev,
+				       struct cpuidle_driver *drv, int index)
+{
+	fpu_idle_fpregs();
+	return __intel_idle(dev, drv, index);
+}
+
 /**
  * intel_idle_s2idle - Ask the processor to enter the given idle state.
  * @dev: cpuidle device of the target CPU.
@@ -1831,6 +1838,9 @@ static void __init intel_idle_init_cstat
 		if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_IRQ_ENABLE)
 			drv->states[drv->state_count].enter = intel_idle_irq;
 
+		if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_INIT_XSTATE)
+			drv->states[drv->state_count].enter = intel_idle_xstate;
+
 		if ((disabled_states_mask & BIT(drv->state_count)) ||
 		    ((icpu->use_acpi || force_use_acpi) &&
 		     intel_idle_off_by_default(mwait_hint) &&