linux-kernel - Re: [PATCH v7 2/4] ACPI: processor

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Message-ID: <Z06Ld/hobdnAQF5w@BLRRASHENOY1.amd.com>
Date: Tue, 3 Dec 2024 10:09:19 +0530
From: "Gautham R. Shenoy" <gautham.shenoy@....com>
To: Patryk Wlazlyn <patryk.wlazlyn@...ux.intel.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	rafael.j.wysocki@...el.com, peterz@...radead.org,
	dave.hansen@...ux.intel.com, tglx@...utronix.de,
	len.brown@...el.com, artem.bityutskiy@...ux.intel.com
Subject: Re: [PATCH v7 2/4] ACPI: processor_idle: Add FFH state handling

On Fri, Nov 29, 2024 at 07:22:30PM +0100, Patryk Wlazlyn wrote:
> Recent Intel platforms will depend on the idle driver to pass the
> correct hint for playing dead via mwait_play_dead_with_hint(). Expand
> the existing enter_dead interface with handling for FFH states and pass
> the MWAIT hint to the mwait_play_dead code.
> 
> Signed-off-by: Patryk Wlazlyn <patryk.wlazlyn@...ux.intel.com>
> Suggested-by: Gautham R. Shenoy <gautham.shenoy@....com>

Looks good to me.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@....com>

--
Thanks and Regards
gautham.

> ---
>  arch/x86/kernel/acpi/cstate.c | 10 ++++++++++
>  drivers/acpi/processor_idle.c |  2 ++
>  include/acpi/processor.h      |  5 +++++
>  3 files changed, 17 insertions(+)
> 
> diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
> index f3ffd0a3a012..8d7b8b02ddb9 100644
> --- a/arch/x86/kernel/acpi/cstate.c
> +++ b/arch/x86/kernel/acpi/cstate.c
> @@ -15,6 +15,7 @@
>  #include <acpi/processor.h>
>  #include <asm/mwait.h>
>  #include <asm/special_insns.h>
> +#include <asm/smp.h>
>  
>  /*
>   * Initialize bm_flags based on the CPU cache properties
> @@ -204,6 +205,15 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
>  }
>  EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
>  
> +void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
> +{
> +	unsigned int cpu = smp_processor_id();
> +	struct cstate_entry *percpu_entry;
> +
> +	percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
> +	mwait_play_dead(percpu_entry->states[cx->index].eax);
> +}
> +
>  void __cpuidle acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
>  {
>  	unsigned int cpu = smp_processor_id();
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index ce728cf7e301..83213fa47c1b 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -590,6 +590,8 @@ static void acpi_idle_play_dead(struct cpuidle_device *dev, int index)
>  			raw_safe_halt();
>  		else if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
>  			io_idle(cx->address);
> +		} else if (cx->entry_method == ACPI_CSTATE_FFH) {
> +			acpi_processor_ffh_play_dead(cx);
>  		} else
>  			return;
>  	}
> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
> index a17e97e634a6..63a37e72b721 100644
> --- a/include/acpi/processor.h
> +++ b/include/acpi/processor.h
> @@ -280,6 +280,7 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
>  				    struct acpi_processor_cx *cx,
>  				    struct acpi_power_register *reg);
>  void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cstate);
> +void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx);
>  #else
>  static inline void acpi_processor_power_init_bm_check(struct
>  						      acpi_processor_flags
> @@ -300,6 +301,10 @@ static inline void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx
>  {
>  	return;
>  }
> +static inline void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
> +{
> +	return;
> +}
>  #endif
>  
>  static inline int call_on_cpu(int cpu, long (*fn)(void *), void *arg,
> -- 
> 2.47.1
>