RE: [PATCH v3 08/15] xen/amd: export processor max frequency value

["Penny, Zheng" <penny.zheng@xxxxxxx>]

[Public]

Hi,

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: Monday, March 24, 2025 11:52 PM
> To: Penny, Zheng <penny.zheng@xxxxxxx>
> Cc: Huang, Ray <Ray.Huang@xxxxxxx>; Andrew Cooper
> <andrew.cooper3@xxxxxxxxxx>; Roger Pau Monné <roger.pau@xxxxxxxxxx>; xen-
> devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3 08/15] xen/amd: export processor max frequency value
>
> On 06.03.2025 09:39, Penny Zheng wrote:
> > --- a/xen/arch/x86/cpu/amd.c
> > +++ b/xen/arch/x86/cpu/amd.c
> > @@ -56,6 +56,8 @@ bool __initdata amd_virt_spec_ctrl;
> >
> >  static bool __read_mostly fam17_c6_disabled;
> >
> > +DEFINE_PER_CPU_READ_MOSTLY(uint64_t, amd_max_freq_mhz);
> > +
> >  static inline int rdmsr_amd_safe(unsigned int msr, unsigned int *lo,
> >                              unsigned int *hi)
> >  {
> > @@ -681,9 +683,15 @@ void amd_log_freq(const struct cpuinfo_x86 *c)
> >             printk("CPU%u: %lu ... %lu MHz\n",
> >                    smp_processor_id(),
> >                    amd_parse_freq(c, lo), amd_parse_freq(c, hi));
> > -   else
> > +   else {
> >             printk("CPU%u: %lu MHz\n", smp_processor_id(),
> >                    amd_parse_freq(c, lo));
> > +           return;
> > +   }
> > +
> > +   /* Store max frequency for amd-cppc cpufreq driver */
> > +   if (hi >> 63)
> > +           this_cpu(amd_max_freq_mhz) = amd_parse_freq(c, hi);
> >  }
>
> As before - typically only the BSP will make it here, due to the conditional 
> at the top
> of the function. IOW you'll observe zeros in the per-CPU data for all other 
> CPUs.
>

I'll extract the processing frequency logic into a new helper, maybe 
amd_process_freq()

> > --- a/xen/arch/x86/include/asm/amd.h
> > +++ b/xen/arch/x86/include/asm/amd.h
> > @@ -174,4 +174,5 @@ bool amd_setup_legacy_ssbd(void);  void
> > amd_set_legacy_ssbd(bool enable);  void amd_set_cpuid_user_dis(bool
> > enable);
> >
> > +DECLARE_PER_CPU(uint64_t, amd_max_freq_mhz);
> >  #endif /* __AMD_H__ */
>
> I'm also pretty sure that I did ask before to maintain a blank line ahead of 
> the
> #endif. Please may I ask that you thoroughly address earlier review comments,
> before submitting a new version?
>

Sorry, I'll be more careful.

> Jan