CMT: [SRU][focal:linux-gcp][PATCH 09/17] intel_idle: Refactor intel_idle_cpuidle_driver_init()

[Cengiz Can]

On 11-09-24 01:27:18, Marcelo Henrique Cerri wrote:
> From: "Rafael J. Wysocki" <rafael.j.wysocki at intel.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/2080324
> 
> Move the C-state verification and checks from
> intel_idle_cpuidle_driver_init() to a separate function,
> intel_idle_verify_cstate(), and make the former call it after
> checking the CPUIDLE_FLAG_UNUSABLE state flag.
> 
> Also combine the drv->states[] updates with the incrementation of
> drv->state_count.
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
> (back ported from commit 9f3d6daf61e5156139cd05643f7f1c2a9b7b49b0)

Very minor nitpick: I've always seen this as `backported from` until now. The
scripts might probably depend on it. I'm not sure if it's only for human
consumption though. 

> [marcelo.cerri: Updated context to keep current IBRS fix]
> Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
> ---
>  drivers/idle/intel_idle.c | 49 ++++++++++++++++++++-------------------
>  1 file changed, 25 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index 945afa633345..6148ec3290c2 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -970,6 +970,22 @@ static void intel_idle_s2idle(struct cpuidle_device *dev,
>  	mwait_idle_with_hints(eax, ecx);
>  }
>  
> +static bool intel_idle_verify_cstate(unsigned int mwait_hint)
> +{
> +	unsigned int mwait_cstate = MWAIT_HINT2CSTATE(mwait_hint) + 1;
> +	unsigned int num_substates = (mwait_substates >> mwait_cstate * 4) &
> +					MWAIT_SUBSTATE_MASK;
> +
> +	/* Ignore the C-state if there are NO sub-states in CPUID for it. */
> +	if (num_substates == 0)
> +		return false;
> +
> +	if (mwait_cstate > 2 && !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
> +		mark_tsc_unstable("TSC halts in idle states deeper than C2");
> +
> +	return true;
> +}
> +
>  static void __setup_broadcast_timer(bool on)
>  {
>  	if (on)
> @@ -1358,10 +1374,10 @@ static void __init intel_idle_cpuidle_driver_init(void)
>  	drv->state_count = 1;
>  
>  	for (cstate = 0; cstate < CPUIDLE_STATE_MAX; ++cstate) {
> -		int num_substates, mwait_hint, mwait_cstate;
> +		unsigned int mwait_hint;
>  
> -		if ((cpuidle_state_table[cstate].enter == NULL) &&
> -		    (cpuidle_state_table[cstate].enter_s2idle == NULL))
> +		if (!cpuidle_state_table[cstate].enter &&
> +		    !cpuidle_state_table[cstate].enter_s2idle)
>  			break;
>  
>  		if (cstate + 1 > max_cstate) {
> @@ -1369,39 +1385,24 @@ static void __init intel_idle_cpuidle_driver_init(void)
>  			break;
>  		}
>  
> -		mwait_hint = flg2MWAIT(cpuidle_state_table[cstate].flags);
> -		mwait_cstate = MWAIT_HINT2CSTATE(mwait_hint);
> -
> -		/* number of sub-states for this state in CPUID.MWAIT */
> -		num_substates = (mwait_substates >> ((mwait_cstate + 1) * 4))
> -					& MWAIT_SUBSTATE_MASK;
> -
> -		/* if NO sub-states for this state in CPUID, skip it */
> -		if (num_substates == 0)
> -			continue;
> -
> -		/* if state marked as disabled, skip it */
> +		/* If marked as unusable, skip this state. */
>  		if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_UNUSABLE) {
>  			pr_debug("state %s is disabled\n",
>  				 cpuidle_state_table[cstate].name);
>  			continue;
>  		}
>  
> -
> -		if (((mwait_cstate + 1) > 2) &&
> -			!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
> -			mark_tsc_unstable("TSC halts in idle"
> -					" states deeper than C2");
> -
> -		drv->states[drv->state_count] =	/* structure copy */
> -			cpuidle_state_table[cstate];
> +		mwait_hint = flg2MWAIT(cpuidle_state_table[cstate].flags);
> +		if (!intel_idle_verify_cstate(mwait_hint))
> +			continue;
>  
>  		if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS) &&
>  		    cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_IBRS) {
>  			drv->states[drv->state_count].enter = intel_idle_ibrs;
>  		}
>  
> -		drv->state_count += 1;
> +		/* Structure copy. */
> +		drv->states[drv->state_count++] = cpuidle_state_table[cstate];
>  	}
>  
>  	if (icpu->byt_auto_demotion_disable_flag) {
> -- 
> 2.34.1
> 
> 
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