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

[Sean Christopherson]

On Mon, Feb 03, 2025, Nikunj A Dadhania wrote:
> Sean Christopherson <seanjc@xxxxxxxxxx> writes:
> > Extract retrieval of TSC frequency information from CPUID into standalone
> > helpers so that TDX guest support and kvmlock can reuse the logic.  Provide
> 
> s/kvmlock/kvmclock
> 
> > 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>
> > ---
> 
> ...
> 
> > +
> > +static inline int cpuid_get_tsc_freq(unsigned int *tsc_khz,
> > +				     unsigned int *crystal_khz)
> 
> Should we add this in patch 6/16 where it is being used for the first time ?

No strong preference on my end.  I put it here mostly to keep each patch focused
on a single subsystem where possible, since the series touches so many areas.  I
also wanted to show the "full" API in a single patch, but I agree that adding a
helper without a user is generally undesirable.