Re: [PATCH v2 11/17] cpufreq/amd-pstate: Replace all AMD_CPPC_* macros with masks

Gautham R. Shenoy
2025-02-17T13:48:36Z

On Fri, Feb 14, 2025 at 06:52:38PM -0600, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
>
> Bitfield masks are easier to follow and less error prone.

LGTM.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>

>
> Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> v2:
> * Add a comment in msr-index.h
> * Pick up tag
> ---
> arch/x86/include/asm/msr-index.h | 20 +++++++++++---------
> arch/x86/kernel/acpi/cppc.c | 2 +-
> drivers/cpufreq/amd-pstate-ut.c | 8 ++++----
> drivers/cpufreq/amd-pstate.c | 16 ++++++----------
> 4 files changed, 22 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
> index 3eadc4d5de837..4bb87884998a0 100644
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -700,15 +700,17 @@
> #define MSR_AMD_CPPC_REQ 0xc00102b3
> #define MSR_AMD_CPPC_STATUS 0xc00102b4
>
> -#define AMD_CPPC_LOWEST_PERF(x) (((x) >> 0) & 0xff)
> -#define AMD_CPPC_LOWNONLIN_PERF(x) (((x) >> 8) & 0xff)
> -#define AMD_CPPC_NOMINAL_PERF(x) (((x) >> 16) & 0xff)
> -#define AMD_CPPC_HIGHEST_PERF(x) (((x) >> 24) & 0xff)
> -
> -#define AMD_CPPC_MAX_PERF(x) (((x) & 0xff) << 0)
> -#define AMD_CPPC_MIN_PERF(x) (((x) & 0xff) << 8)
> -#define AMD_CPPC_DES_PERF(x) (((x) & 0xff) << 16)
> -#define AMD_CPPC_ENERGY_PERF_PREF(x) (((x) & 0xff) << 24)
> +/* Masks for use with MSR_AMD_CPPC_CAP1 */
> +#define AMD_CPPC_LOWEST_PERF_MASK GENMASK(7, 0)
> +#define AMD_CPPC_LOWNONLIN_PERF_MASK GENMASK(15, 8)
> +#define AMD_CPPC_NOMINAL_PERF_MASK GENMASK(23, 16)
> +#define AMD_CPPC_HIGHEST_PERF_MASK GENMASK(31, 24)
> +
> +/* Masks for use with MSR_AMD_CPPC_REQ */
> +#define AMD_CPPC_MAX_PERF_MASK GENMASK(7, 0)
> +#define AMD_CPPC_MIN_PERF_MASK GENMASK(15, 8)
> +#define AMD_CPPC_DES_PERF_MASK GENMASK(23, 16)
> +#define AMD_CPPC_EPP_PERF_MASK GENMASK(31, 24)
>
> /* AMD Performance Counter Global Status and Control MSRs */
> #define MSR_AMD64_PERF_CNTR_GLOBAL_STATUS 0xc0000300
> diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
> index f96053c305c61..77bfb846490c0 100644
> --- a/arch/x86/kernel/acpi/cppc.c
> +++ b/arch/x86/kernel/acpi/cppc.c
> @@ -151,7 +151,7 @@ int amd_get_highest_perf(unsigned int cpu, u32 *highest_perf)
> if (ret)
> goto out;
>
> - val = AMD_CPPC_HIGHEST_PERF(val);
> + val = FIELD_GET(AMD_CPPC_HIGHEST_PERF_MASK, val);
> } else {
> ret = cppc_get_highest_perf(cpu, &val);
> if (ret)
> diff --git a/drivers/cpufreq/amd-pstate-ut.c b/drivers/cpufreq/amd-pstate-ut.c
> index 9db20ac357042..067e9e325102e 100644
> --- a/drivers/cpufreq/amd-pstate-ut.c
> +++ b/drivers/cpufreq/amd-pstate-ut.c
> @@ -142,10 +142,10 @@ static int amd_pstate_ut_check_perf(u32 index)
> return ret;
> }
>
> - highest_perf = AMD_CPPC_HIGHEST_PERF(cap1);
> - nominal_perf = AMD_CPPC_NOMINAL_PERF(cap1);
> - lowest_nonlinear_perf = AMD_CPPC_LOWNONLIN_PERF(cap1);
> - lowest_perf = AMD_CPPC_LOWEST_PERF(cap1);
> + highest_perf = FIELD_GET(AMD_CPPC_HIGHEST_PERF_MASK, cap1);
> + nominal_perf = FIELD_GET(AMD_CPPC_NOMINAL_PERF_MASK, cap1);
> + lowest_nonlinear_perf = FIELD_GET(AMD_CPPC_LOWNONLIN_PERF_MASK, cap1);
> + lowest_perf = FIELD_GET(AMD_CPPC_LOWEST_PERF_MASK, cap1);
> }
>
> cur_perf = READ_ONCE(cpudata->perf);
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index e5983e5c77ba2..0a7e69fd32dbf 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -89,11 +89,6 @@ static bool cppc_enabled;
> static bool amd_pstate_prefcore = true;
> static struct quirk_entry *quirks;
>
> -#define AMD_CPPC_MAX_PERF_MASK GENMASK(7, 0)
> -#define AMD_CPPC_MIN_PERF_MASK GENMASK(15, 8)
> -#define AMD_CPPC_DES_PERF_MASK GENMASK(23, 16)
> -#define AMD_CPPC_EPP_PERF_MASK GENMASK(31, 24)
> -
> /*
> * AMD Energy Preference Performance (EPP)
> * The EPP is used in the CCLK DPM controller to drive
> @@ -439,12 +434,13 @@ static int msr_init_perf(struct amd_cpudata *cpudata)
>
> perf.highest_perf = numerator;
> perf.max_limit_perf = numerator;
> - perf.min_limit_perf = AMD_CPPC_LOWEST_PERF(cap1);
> - perf.nominal_perf = AMD_CPPC_NOMINAL_PERF(cap1);
> - perf.lowest_nonlinear_perf = AMD_CPPC_LOWNONLIN_PERF(cap1);
> - perf.lowest_perf = AMD_CPPC_LOWEST_PERF(cap1);
> + perf.min_limit_perf = FIELD_GET(AMD_CPPC_LOWEST_PERF_MASK, cap1);
> + perf.nominal_perf = FIELD_GET(AMD_CPPC_NOMINAL_PERF_MASK, cap1);
> + perf.lowest_nonlinear_perf = FIELD_GET(AMD_CPPC_LOWNONLIN_PERF_MASK, cap1);
> + perf.lowest_perf = FIELD_GET(AMD_CPPC_LOWEST_PERF_MASK, cap1);
> WRITE_ONCE(cpudata->perf, perf);
> - WRITE_ONCE(cpudata->prefcore_ranking, AMD_CPPC_HIGHEST_PERF(cap1));
> + WRITE_ONCE(cpudata->prefcore_ranking, FIELD_GET(AMD_CPPC_HIGHEST_PERF_MASK, cap1));
> +
> return 0;
> }
>
> --
> 2.43.0
>

--
Thanks and Regards
gautham.