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

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Message-ID: <YqHKKa/yamRS06tC@worktop.programming.kicks-ass.net>
Date:   Thu, 9 Jun 2022 12:23:37 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     linux-kernel@...r.kernel.org
Cc:     linux-tip-commits@...r.kernel.org, Zhang Rui <rui.zhang@...el.com>,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, x86@...nel.org
Subject: Re: [tip: x86/fpu] intel_idle: Add a new flag to initialize the AMX
 state

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) &&