Re: [PATCH 01/16] x86/tsc: Add a standalone helpers for getting TSC info from CPUID.0x15

[Borislav Petkov <bp@xxxxxxxxx>]

On Fri, Jan 31, 2025 at 06:17:03PM -0800, Sean Christopherson wrote:
> Extract retrieval of TSC frequency information from CPUID into standalone
> helpers so that TDX guest support and kvmlock can reuse the logic.  Provide
> a version that includes the multiplier math as TDX in particular does NOT
> want to use native_calibrate_tsc()'s fallback logic that derives the TSC
> frequency based on CPUID.0x16 when the core crystal frequency isn't known.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/tsc.h | 41 ++++++++++++++++++++++++++++++++++++++
>  arch/x86/kernel/tsc.c      | 14 ++-----------
>  2 files changed, 43 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
> index 94408a784c8e..14a81a66b37c 100644
> --- a/arch/x86/include/asm/tsc.h
> +++ b/arch/x86/include/asm/tsc.h

Bah, why in the header as inlines? Just leave them in tsc.c and call them...

> @@ -28,6 +28,47 @@ static inline cycles_t get_cycles(void)
>  }
>  #define get_cycles get_cycles
>  
> +static inline int cpuid_get_tsc_info(unsigned int *crystal_khz,
> +                                  unsigned int *denominator,
> +                                  unsigned int *numerator)

Can we pls do a

struct cpuid_tsc_info {
        unsigned int denominator;
        unsigned int numerator;
        unsigned int crystal_khz;
        unsigned int tsc_khz;
}

and hand that around instead of those I/O pointers?

It would make the code a bit saner to stare at and follow.

Thx.

-- 
Regards/Gruss,
    Boris.

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