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Message-ID: <CAJZ5v0iXzpD_DNWOroncHL+XkSznv+meQf74OiHcbQMqbAC4ug@mail.gmail.com>
Date: Fri, 23 Apr 2021 17:19:46 +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 v2] x86, sched: Fix the AMD CPPC maximum perf on some
specific generations
On Wed, Apr 21, 2021 at 4:38 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.
>
> ---
> arch/x86/include/asm/processor.h | 2 ++
> arch/x86/kernel/cpu/amd.c | 22 ++++++++++++++++++++++
> arch/x86/kernel/smpboot.c | 2 +-
> drivers/cpufreq/acpi-cpufreq.c | 19 +++++++++++++++++++
> 4 files changed, 44 insertions(+), 1 deletion(-)
>
> 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..aadb691d9357 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -1170,3 +1170,25 @@ void set_dr_addr_mask(unsigned long mask, int dr)
> break;
> }
> }
> +
> +u32 amd_get_highest_perf(void)
> +{
> + struct cpuinfo_x86 *c = &boot_cpu_data;
> + u32 cppc_max_perf = 225;
The extra local variable is redundant.
> +
> + switch (c->x86) {
> + case 0x17:
> + if ((c->x86_model >= 0x30 && c->x86_model < 0x40) ||
> + (c->x86_model >= 0x70 && c->x86_model < 0x80))
> + cppc_max_perf = 166;
> + break;
Also it would be cleaner to write this as
if (c->x86 == 0x17 && ((c->x86_model >= 0x30 && c->x86_model < 0x40) ||
(c->x86_model >= 0x70 && c->x86_model < 0x80))
return 166;
And analogously below.
> + case 0x19:
> + if ((c->x86_model >= 0x20 && c->x86_model < 0x30) ||
> + (c->x86_model >= 0x40 && c->x86_model < 0x70))
> + cppc_max_perf = 166;
> + break;
> + }
> +
> + return cppc_max_perf;
And here
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..3f0a19dd658c 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -630,6 +630,22 @@ static int acpi_cpufreq_blacklist(struct cpuinfo_x86 *c)
> #endif
>
> #ifdef CONFIG_ACPI_CPPC_LIB
> +
> +static u64 get_amd_max_boost_ratio(unsigned int cpu, u64 nominal_perf)
> +{
> + u64 boost_ratio, cppc_max_perf;
> +
> + if (!nominal_perf)
> + return 0;
> +
> + cppc_max_perf = amd_get_highest_perf();
> +
> + boost_ratio = div_u64(cppc_max_perf << SCHED_CAPACITY_SHIFT,
> + nominal_perf);
> +
> + return boost_ratio;
> +}
The function above is not necessary if I'm not mistaken.
> +
> static u64 get_max_boost_ratio(unsigned int cpu)
> {
> struct cppc_perf_caps perf_caps;
> @@ -646,6 +662,9 @@ static u64 get_max_boost_ratio(unsigned int cpu)
> return 0;
> }
>
> + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
> + return get_amd_max_boost_ratio(cpu, perf_caps.nominal_perf);
> +
> highest_perf = perf_caps.highest_perf;
The above can be written as
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;
>
> --
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