linux-kernel - Re: [PATCH v4 5/8] arm64: Create cache sysfs directory without ACPI PPTT for hardware prefetch control

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Date:   Wed, 18 May 2022 09:09:52 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Kohei Tarumizu <tarumizu.kohei@...itsu.com>
Cc:     catalin.marinas@....com, will@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, rafael@...nel.org,
        mchehab+huawei@...nel.org, eugenis@...gle.com, tony.luck@...el.com,
        pcc@...gle.com, peterz@...radead.org, marcos@...a.pet,
        conor.dooley@...rochip.com, nicolas.ferre@...rochip.com,
        marcan@...can.st, linus.walleij@...aro.org, arnd@...db.de,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 5/8] arm64: Create cache sysfs directory without ACPI
 PPTT for hardware prefetch control

On Wed, May 18, 2022 at 03:30:29PM +0900, Kohei Tarumizu wrote:
> Create a cache sysfs directory without ACPI PPTT if the
> CONFIG_HWPF_CONTROL is true.
> 
> Hardware prefetch control driver need cache sysfs directory and cache
> level/type information. In ARM processor, these information can be
> obtained from the register even without PPTT.
> 
> This patch set the cpu_map_populated to true if the machine doesn't
> have PPTT. It use only the level/type information obtained from
> CLIDR_EL1, and don't use CCSIDR information.
> 
> Signed-off-by: Kohei Tarumizu <tarumizu.kohei@...itsu.com>
> ---
>  arch/arm64/kernel/cacheinfo.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
> index 587543c6c51c..039ec32d0b3d 100644
> --- a/arch/arm64/kernel/cacheinfo.c
> +++ b/arch/arm64/kernel/cacheinfo.c
> @@ -43,6 +43,21 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
>  	this_leaf->type = type;
>  }
>  
> +#if defined(CONFIG_HWPF_CONTROL)

Please do not put #if in .c files.

> +static bool acpi_has_pptt(void)
> +{
> +	struct acpi_table_header *table;
> +	acpi_status status;
> +
> +	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
> +	if (ACPI_FAILURE(status))
> +		return false;
> +
> +	acpi_put_table(table);
> +	return true;
> +}
> +#endif
> +
>  int init_cache_level(unsigned int cpu)
>  {
>  	unsigned int ctype, level, leaves, fw_level;
> @@ -95,5 +110,19 @@ int populate_cache_leaves(unsigned int cpu)
>  			ci_leaf_init(this_leaf++, type, level);
>  		}
>  	}
> +
> +#if defined(CONFIG_HWPF_CONTROL)
> +	/*
> +	 * Hardware prefetch functions need cache sysfs directory and cache
> +	 * level/type information. In ARM processor, these information can be
> +	 * obtained from registers even without PPTT. Therefore, we set the
> +	 * cpu_map_populated to true to create cache sysfs directory, if the
> +	 * machine doesn't have PPTT.
> +	 **/
> +	if (!acpi_disabled)
> +		if (!acpi_has_pptt())
> +			this_cpu_ci->cpu_map_populated = true;
> +#endif

Same here, no #if is needed if you do it properly in your .h file.

thanks,

greg k-h