On Fri, 2026-04-10 at 14:19 +0200, Thomas Gleixner wrote: > get_cycles() is not really well defined and similar to other usaage of the > underlying hardware CPU counters the PTP vmclock should use an explicit > interface as well. > > Implement ptp_vmclock_read_cpu_counter() in arm64 and x86 and simplify the > Kconfig selection while at it. > > No functional change. > > Signed-off-by: Thomas Gleixner <[email protected]> > Cc: David Woodhouse <[email protected]>
Acked-by: David Woodhouse <[email protected]> Although I might follow up with a change to make this... > +static inline u64 ptp_vmclock_read_cpu_counter(void) > +{ > + return cpu_feature_enabled(X86_FEATURE_TSC) ? rdtsc() : 0; > +} > + ... depend on TSC_RELIABLE¹, since if the guest doesn't believe that it is, then the guest shouldn't be trying to use it as the basis for precise timing. ¹ (Or... one of the other zoo of TSC flags for the gradually reducing brokenness over the years...)
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