Re: [PATCH v3] x86, sched: Fix the AMD CPPC maximum perf on some specific generations

[Huang Rui <ray.huang@xxxxxxx>]

On Fri, Apr 23, 2021 at 08:09:49PM +0800, Rafael J. Wysocki wrote:
> On Fri, Apr 23, 2021 at 4:40 AM Huang Rui <ray.huang@xxxxxxx> 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:
> >
> > ~ $B"*(B 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@xxxxxxxxx>
> > Tested-by: Jason Bagavatsingham <jason.bagavatsingham@xxxxxxxxx>
> > Bugzilla: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.kernel.org%2Fshow_bug.cgi%3Fid%3D211791&amp;data=04%7C01%7Cray.huang%40amd.com%7Ce9ed877387fc4b7431e108d90650b98f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637547766057950380%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=R%2FSBLaYOhTjrli%2BT054EytKeh8VmN7ryOQuQW4mgz6M%3D&amp;reserved=0
> > Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
> > Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> > Cc: Nathan Fontenot <nathan.fontenot@xxxxxxx>
> > Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > Cc: Borislav Petkov <bp@xxxxxxx>
> > Cc: x86@xxxxxxxxxx
> > Cc: stable@xxxxxxxxxxxxxxx
> > ---
> >
> > 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.
> >
> > ---
> >  arch/x86/include/asm/processor.h |  2 ++
> >  arch/x86/kernel/cpu/amd.c        | 22 ++++++++++++++++++++++
> >  drivers/acpi/cppc_acpi.c         |  8 ++++++--
> >  3 files changed, 30 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..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;
> > +
> > +       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;
> > +       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;
> > +}
> > +EXPORT_SYMBOL_GPL(amd_get_highest_perf);
> > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> > index 69057fcd2c04..58e72b6e222f 100644
> > --- a/drivers/acpi/cppc_acpi.c
> > +++ b/drivers/acpi/cppc_acpi.c
> > @@ -1107,8 +1107,12 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
> >                 }
> >         }
> >
> > -       cpc_read(cpunum, highest_reg, &high);
> > -       perf_caps->highest_perf = high;
> > +       if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
> 
> This is a generic arch-independent file.
> 
> Can we avoid adding the x86-specific check here?

OK, I see, it will be used by ARM as well.

Can I rollback to implementation of V2:

https://lore.kernel.org/r/20210421023807.1540290-1-ray.huang@xxxxxxx

If stick to add quirk in cppc_acpi.c and avoid x86-specific check at the
same time here, the code will not be straight forward. Or will you have any
other good idea?

Thanks,
Ray