| Message ID | 20240828101035.2099-2-gautham.shenoy@amd.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Mario Limonciello |
| Headers | show |
| Series | cpufreq/amd-pstate: Fix warnings for X86_FEATURE_CPPC | expand |
On 8/28/2024 05:10, Gautham R. Shenoy wrote: > commit bff7d13c190a ("cpufreq: amd-pstate: add debug message while > CPPC is supported and disabled by SBIOS") issues a warning on plaforms > where the X86_FEATURE_CPPC is expected to be enabled, but is not due > to it being disabled in the BIOS. > > This feature bit corresponds to CPUID 0x80000008.ebx[27] which is a > reserved bit on the Zen1 processors and a reserved bit on Zen2 based > models 0x70-0x7F, and is expected to be cleared on these > platforms. Thus printing the warning message for these models when > X86_FEATURE_CPPC is unavailable is incorrect. Fix this. > > Modify some of the comments, and use switch-case for model range > checking for improved readability while at it. > > Fixes: bff7d13c190a ("cpufreq: amd-pstate: add debug message while CPPC is supported and disabled by SBIOS") > Cc: Xiaojian Du <xiaojian.du@amd.com> > Reported-by: David Wang <00107082@163.com> > Closes: https://lore.kernel.org/lkml/20240730140111.4491-1-00107082@163.com/ > Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Thanks! Acked-by: Mario Limonciello <mario.limonciello@amd.com> Will apply to fixes branch. > --- > drivers/cpufreq/amd-pstate.c | 34 ++++++++++++++++++++++++---------- > 1 file changed, 24 insertions(+), 10 deletions(-) > > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c > index 89bda7a2bb8d..259a917da75f 100644 > --- a/drivers/cpufreq/amd-pstate.c > +++ b/drivers/cpufreq/amd-pstate.c > @@ -1834,20 +1834,34 @@ static bool amd_cppc_supported(void) > } > > /* > - * If the CPPC feature is disabled in the BIOS for processors that support MSR-based CPPC, > - * the AMD Pstate driver may not function correctly. > - * Check the CPPC flag and display a warning message if the platform supports CPPC. > - * Note: below checking code will not abort the driver registeration process because of > - * the code is added for debugging purposes. > + * If the CPPC feature is disabled in the BIOS for processors > + * that support MSR-based CPPC, the AMD Pstate driver may not > + * function correctly. > + * > + * For such processors, check the CPPC flag and display a > + * warning message if the platform supports CPPC. > + * > + * Note: The code check below will not abort the driver > + * registration process because of the code is added for > + * debugging purposes. Besides, it may still be possible for > + * the driver to work using the shared-memory mechanism. > */ > if (!cpu_feature_enabled(X86_FEATURE_CPPC)) { > - if (cpu_feature_enabled(X86_FEATURE_ZEN1) || cpu_feature_enabled(X86_FEATURE_ZEN2)) { > - if (c->x86_model > 0x60 && c->x86_model < 0xaf) > + if (cpu_feature_enabled(X86_FEATURE_ZEN2)) { > + switch (c->x86_model) { > + case 0x60 ... 0x6F: > + case 0x80 ... 0xAF: > warn = true; > - } else if (cpu_feature_enabled(X86_FEATURE_ZEN3) || cpu_feature_enabled(X86_FEATURE_ZEN4)) { > - if ((c->x86_model > 0x10 && c->x86_model < 0x1F) || > - (c->x86_model > 0x40 && c->x86_model < 0xaf)) > + break; > + } > + } else if (cpu_feature_enabled(X86_FEATURE_ZEN3) || > + cpu_feature_enabled(X86_FEATURE_ZEN4)) { > + switch (c->x86_model) { > + case 0x10 ... 0x1F: > + case 0x40 ... 0xAF: > warn = true; > + break; > + } > } else if (cpu_feature_enabled(X86_FEATURE_ZEN5)) { > warn = true; > }
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 89bda7a2bb8d..259a917da75f 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -1834,20 +1834,34 @@ static bool amd_cppc_supported(void) } /* - * If the CPPC feature is disabled in the BIOS for processors that support MSR-based CPPC, - * the AMD Pstate driver may not function correctly. - * Check the CPPC flag and display a warning message if the platform supports CPPC. - * Note: below checking code will not abort the driver registeration process because of - * the code is added for debugging purposes. + * If the CPPC feature is disabled in the BIOS for processors + * that support MSR-based CPPC, the AMD Pstate driver may not + * function correctly. + * + * For such processors, check the CPPC flag and display a + * warning message if the platform supports CPPC. + * + * Note: The code check below will not abort the driver + * registration process because of the code is added for + * debugging purposes. Besides, it may still be possible for + * the driver to work using the shared-memory mechanism. */ if (!cpu_feature_enabled(X86_FEATURE_CPPC)) { - if (cpu_feature_enabled(X86_FEATURE_ZEN1) || cpu_feature_enabled(X86_FEATURE_ZEN2)) { - if (c->x86_model > 0x60 && c->x86_model < 0xaf) + if (cpu_feature_enabled(X86_FEATURE_ZEN2)) { + switch (c->x86_model) { + case 0x60 ... 0x6F: + case 0x80 ... 0xAF: warn = true; - } else if (cpu_feature_enabled(X86_FEATURE_ZEN3) || cpu_feature_enabled(X86_FEATURE_ZEN4)) { - if ((c->x86_model > 0x10 && c->x86_model < 0x1F) || - (c->x86_model > 0x40 && c->x86_model < 0xaf)) + break; + } + } else if (cpu_feature_enabled(X86_FEATURE_ZEN3) || + cpu_feature_enabled(X86_FEATURE_ZEN4)) { + switch (c->x86_model) { + case 0x10 ... 0x1F: + case 0x40 ... 0xAF: warn = true; + break; + } } else if (cpu_feature_enabled(X86_FEATURE_ZEN5)) { warn = true; }
commit bff7d13c190a ("cpufreq: amd-pstate: add debug message while CPPC is supported and disabled by SBIOS") issues a warning on plaforms where the X86_FEATURE_CPPC is expected to be enabled, but is not due to it being disabled in the BIOS. This feature bit corresponds to CPUID 0x80000008.ebx[27] which is a reserved bit on the Zen1 processors and a reserved bit on Zen2 based models 0x70-0x7F, and is expected to be cleared on these platforms. Thus printing the warning message for these models when X86_FEATURE_CPPC is unavailable is incorrect. Fix this. Modify some of the comments, and use switch-case for model range checking for improved readability while at it. Fixes: bff7d13c190a ("cpufreq: amd-pstate: add debug message while CPPC is supported and disabled by SBIOS") Cc: Xiaojian Du <xiaojian.du@amd.com> Reported-by: David Wang <00107082@163.com> Closes: https://lore.kernel.org/lkml/20240730140111.4491-1-00107082@163.com/ Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com> --- drivers/cpufreq/amd-pstate.c | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-)