linux-kernel - Re: [PATCH v4] x86, sched: Fix the AMD CPPC maximum perf on some specific generations

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Date:   Wed, 28 Apr 2021 19:08:20 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Huang Rui <ray.huang@....com>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Alex Deucher <alexander.deucher@....com>,
        Jason Bagavatsingham <jason.bagavatsingham@...il.com>,
        "Pierre-Loup A . Griffais" <pgriffais@...vesoftware.com>,
        Nathan Fontenot <nathan.fontenot@....com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Borislav Petkov <bp@...e.de>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Stable <stable@...r.kernel.org>
Subject: Re: [PATCH v4] x86, sched: Fix the AMD CPPC maximum perf on some
 specific generations

On Sun, Apr 25, 2021 at 9:35 AM Huang Rui <ray.huang@....com> wrote:
>
> Some AMD Ryzen generations has different calculation method on maximum
> perf. 255 is not for all asics, some specific generations should use 166
> as the maximum perf. Otherwise, it will report incorrect frequency value
> like below:
>
> ~ → lscpu | grep MHz
> CPU MHz:                         3400.000
> CPU max MHz:                     7228.3198
> CPU min MHz:                     2200.0000
>
> Fixes: 41ea667227ba ("x86, sched: Calculate frequency invariance for AMD systems")
> Fixes: 3c55e94c0ade ("cpufreq: ACPI: Extend frequency tables to cover boost frequencies")
>
> Reported-by: Jason Bagavatsingham <jason.bagavatsingham@...il.com>
> Tested-by: Jason Bagavatsingham <jason.bagavatsingham@...il.com>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211791
> Signed-off-by: Huang Rui <ray.huang@....com>
> Cc: Alex Deucher <alexander.deucher@....com>
> Cc: Nathan Fontenot <nathan.fontenot@....com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: x86@...nel.org
> Cc: stable@...r.kernel.org
> ---
>
> Changes from V1 -> V2:
> - Enhance the commit message.
> - Move amd_get_highest_perf() into amd.c.
> - Refine the implementation of switch-case.
> - Cc stable mail list.
>
> Changes from V2 -> V3:
> - Move the update into cppc_get_perf_caps() to correct the highest perf value in
>   the API.
>
> Changes from V3 -> V4:
> - Rollback to V2 implementation because acpi_cppc.c will be used by ARM as well.
>   It's not good to add x86-specific calling there.
> - Simplify the implementation of the functions.

All of my comments have been addressed, so:

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

and I'm expecting the x86 maintainers to take care of this patch.

> ---
>  arch/x86/include/asm/processor.h |  2 ++
>  arch/x86/kernel/cpu/amd.c        | 16 ++++++++++++++++
>  arch/x86/kernel/smpboot.c        |  2 +-
>  drivers/cpufreq/acpi-cpufreq.c   |  6 +++++-
>  4 files changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index f1b9ed5efaa9..908bcaea1361 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -804,8 +804,10 @@ DECLARE_PER_CPU(u64, msr_misc_features_shadow);
>
>  #ifdef CONFIG_CPU_SUP_AMD
>  extern u32 amd_get_nodes_per_socket(void);
> +extern u32 amd_get_highest_perf(void);
>  #else
>  static inline u32 amd_get_nodes_per_socket(void)       { return 0; }
> +static inline u32 amd_get_highest_perf(void)           { return 0; }
>  #endif
>
>  static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves)
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index 347a956f71ca..bc3496669def 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -1170,3 +1170,19 @@ void set_dr_addr_mask(unsigned long mask, int dr)
>                 break;
>         }
>  }
> +
> +u32 amd_get_highest_perf(void)
> +{
> +       struct cpuinfo_x86 *c = &boot_cpu_data;
> +
> +       if (c->x86 == 0x17 && ((c->x86_model >= 0x30 && c->x86_model < 0x40) ||
> +                              (c->x86_model >= 0x70 && c->x86_model < 0x80)))
> +           return 166;
> +
> +       if (c->x86 == 0x19 && ((c->x86_model >= 0x20 && c->x86_model < 0x30) ||
> +                              (c->x86_model >= 0x40 && c->x86_model < 0x70)))
> +           return 166;
> +
> +       return 225;
> +}
> +EXPORT_SYMBOL_GPL(amd_get_highest_perf);
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 02813a7f3a7c..7bec57d04a87 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -2046,7 +2046,7 @@ static bool amd_set_max_freq_ratio(void)
>                 return false;
>         }
>
> -       highest_perf = perf_caps.highest_perf;
> +       highest_perf = amd_get_highest_perf();
>         nominal_perf = perf_caps.nominal_perf;
>
>         if (!highest_perf || !nominal_perf) {
> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> index d1bbc16fba4b..7e7450453714 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -646,7 +646,11 @@ static u64 get_max_boost_ratio(unsigned int cpu)
>                 return 0;
>         }
>
> -       highest_perf = perf_caps.highest_perf;
> +       if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
> +               highest_perf = amd_get_highest_perf();
> +       else
> +               highest_perf = perf_caps.highest_perf;
> +
>         nominal_perf = perf_caps.nominal_perf;
>
>         if (!highest_perf || !nominal_perf) {
> --
> 2.25.1
>