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Message-ID: <CAJZ5v0jGTzRNgA7HM-r=TuhHyy0gvMuNEgz5wZ2hPkqwyFa6og@mail.gmail.com>
Date: Mon, 4 Nov 2024 22:10:59 +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 v3] ACPI: processor: Move arch_init_invariance_cppc() call later
On Mon, Nov 4, 2024 at 9:54 PM 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, change arch_init_invariance_cppc() into a new weak
> symbol that is called at the end of acpi_processor_driver_init().
> Each architecture that supports it can declare the symbol to override
> the weak one.
>
> 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>
> ---
> v3:
> * Weak symbol instead of macro to help riscv build failure
> * Update commit message
> * Add comment
> ---
> arch/arm64/include/asm/topology.h | 2 +-
> arch/x86/include/asm/topology.h | 2 +-
> drivers/acpi/cppc_acpi.c | 6 ------
> drivers/acpi/processor_driver.c | 9 +++++++++
> include/acpi/processor.h | 2 ++
> 5 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
> index 5fc3af9f8f29b..8a1860877967e 100644
> --- a/arch/arm64/include/asm/topology.h
> +++ b/arch/arm64/include/asm/topology.h
> @@ -27,7 +27,7 @@ void update_freq_counters_refs(void);
> #define arch_scale_freq_ref topology_get_freq_ref
>
> #ifdef CONFIG_ACPI_CPPC_LIB
> -#define arch_init_invariance_cppc topology_init_cpu_capacity_cppc
> +#define acpi_processor_init_invariance_cppc topology_init_cpu_capacity_cppc
> #endif
>
> /* Replace task scheduler's default cpu-invariant accounting */
> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index aef70336d6247..0fb705524aeaa 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -307,7 +307,7 @@ 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
> +#define acpi_processor_init_invariance_cppc init_freq_invariance_cppc
> #endif
>
> #endif /* _ASM_X86_TOPOLOGY_H */
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 1a40f0514eaa3..5c0cc7aae8726 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 cb52dd000b958..3b281bc1e73c3 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -237,6 +237,9 @@ static struct notifier_block acpi_processor_notifier_block = {
> .notifier_call = acpi_processor_notifier,
> };
>
> +void __weak acpi_processor_init_invariance_cppc(void)
> +{ }
Does this actually work if acpi_processor_init_invariance_cppc is a
macro? How does the compiler know that it needs to use
init_freq_invariance_cppc() instead of this?
It would work if a __weak definition of init_freq_invariance_cppc() was present.
> +
> /*
> * We keep the driver loaded even when ACPI is not running.
> * This is needed for the powernow-k8 driver, that works even without
> @@ -270,6 +273,12 @@ static int __init acpi_processor_driver_init(void)
> NULL, acpi_soft_cpu_dead);
>
> acpi_processor_throttling_init();
> +
> + /*
> + * Frequency invariance calculations on AMD platforms can't be run until
> + * after acpi_cppc_processor_probe() has been called for all online CPUs.
> + */
> + acpi_processor_init_invariance_cppc();
> return 0;
> err:
> driver_unregister(&acpi_processor_driver);
> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
> index e6f6074eadbf3..a17e97e634a68 100644
> --- a/include/acpi/processor.h
> +++ b/include/acpi/processor.h
> @@ -465,4 +465,6 @@ extern int acpi_processor_ffh_lpi_probe(unsigned int cpu);
> extern int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi);
> #endif
>
> +void acpi_processor_init_invariance_cppc(void);
> +
> #endif
>
> base-commit: 6db936d4ac0fe281af48b4d1ebf69b1523bbac31
> --
> 2.43.0
>
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