linux-kernel - Re: [PATCH v2] ACPI: processor: Move arch_init_invariance

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Message-ID: <CAJZ5v0hVbJctHHMS4=c74Y1+qOw2VRfevkPi9W99nHHPejNw0w@mail.gmail.com>
Date: Mon, 4 Nov 2024 17:55:16 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Mario Limonciello <superm1@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>, "Rafael J . Wysocki" <rafael@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, 
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>, Len Brown <lenb@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Mario Limonciello <mario.limonciello@....com>, 
	"Gautham R . Shenoy" <gautham.shenoy@....com>, 
	"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <linux-kernel@...r.kernel.org>, 
	"open list:ACPI" <linux-acpi@...r.kernel.org>, Ivan Shapovalov <intelfx@...elfx.name>, 
	Oleksandr Natalenko <oleksandr@...alenko.name>
Subject: Re: [PATCH v2] ACPI: processor: Move arch_init_invariance_cppc() call later

On Sat, Nov 2, 2024 at 4:24 AM Mario Limonciello <superm1@...nel.org> wrote:
>
> From: Mario Limonciello <mario.limonciello@....com>
>
> arch_init_invariance_cppc() is called at the end of
> acpi_cppc_processor_probe() in order to configure frequency invariance
> based upon the values from _CPC.
>
> This however doesn't work on AMD CPPC shared memory designs that have
> AMD preferred cores enabled because _CPC needs to be analyzed from all
> cores to judge if preferred cores are enabled.
>
> This issue manifests to users as a warning since commit 21fb59ab4b97
> ("ACPI: CPPC: Adjust debug messages in amd_set_max_freq_ratio() to warn"):
> ```
> Could not retrieve highest performance (-19)
> ```
>
> However the warning isn't the cause of this, it was actually
> commit 279f838a61f9 ("x86/amd: Detect preferred cores in
> amd_get_boost_ratio_numerator()") which exposed the issue.
>
> To fix this problem, push the call to the arch_init_invariance_cppc()
> macro to the end of acpi_processor_driver_init().
>
> Fixes: 279f838a61f9 ("x86/amd: Detect preferred cores in amd_get_boost_ratio_numerator()")
> Reported-by: Ivan Shapovalov <intelfx@...elfx.name>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219431
> Tested-by: Oleksandr Natalenko <oleksandr@...alenko.name>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
> v1->v2:
>  * Fix LKP robot issue when CONFIG_ACPI_CPPC_LIB not defined
> ---
>  arch/x86/include/asm/topology.h | 2 ++
>  drivers/acpi/cppc_acpi.c        | 6 ------
>  drivers/acpi/processor_driver.c | 1 +
>  3 files changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index abe3a8f22cbd..b04c5db7e945 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -295,6 +295,8 @@ extern void arch_scale_freq_tick(void);
>  #ifdef CONFIG_ACPI_CPPC_LIB
>  void init_freq_invariance_cppc(void);
>  #define arch_init_invariance_cppc init_freq_invariance_cppc
> +#else
> +static inline void arch_init_invariance_cppc(void) { }
>  #endif
>
>  #endif /* _ASM_X86_TOPOLOGY_H */
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index ed91dfd4fdca..9d48cd706659 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -671,10 +671,6 @@ static int pcc_data_alloc(int pcc_ss_id)
>   *  )
>   */
>
> -#ifndef arch_init_invariance_cppc
> -static inline void arch_init_invariance_cppc(void) { }
> -#endif
> -
>  /**
>   * acpi_cppc_processor_probe - Search for per CPU _CPC objects.
>   * @pr: Ptr to acpi_processor containing this CPU's logical ID.
> @@ -905,8 +901,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
>                 goto out_free;
>         }
>
> -       arch_init_invariance_cppc();
> -
>         kfree(output.pointer);
>         return 0;
>
> diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
> index cb52dd000b95..59620e7bc664 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -270,6 +270,7 @@ static int __init acpi_processor_driver_init(void)
>                                   NULL, acpi_soft_cpu_dead);
>
>         acpi_processor_throttling_init();
> +       arch_init_invariance_cppc();
>         return 0;
>  err:
>         driver_unregister(&acpi_processor_driver);
> --

Applied as a fix for 6.12-rc7.

However, it would be good to add a comment explaining why
acpi_processor_driver_init() calls arch_init_invariance_cppc() at the
end.  The ACPI processor driver and CPPC are not otherwise related I
think?