Re: [PATCH V4 1/4] KVM: x86: hyper-v: Calculate APIC bus frequency for Hyper-V

[Edgecombe, Rick P]

On Thu, 2024-03-21 at 09:37 -0700, Reinette Chatre wrote:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> 
> Remove APIC_BUS_FREQUENCY and calculate it based on nanoseconds per APIC
> bus cycle.  APIC_BUS_FREQUENCY is used only for HV_X64_MSR_APIC_FREQUENCY.
> The MSR is not frequently read, calculate it every time.
> 
> There are two constants related to the APIC bus frequency:
> APIC_BUS_FREQUENCY and APIC_BUS_CYCLE_NS.
> Only one value is required because one can be calculated from the other:
>    APIC_BUS_CYCLES_NS = 1000 * 1000 * 1000 / APIC_BUS_FREQUENCY.
> 
> Remove APIC_BUS_FREQUENCY and instead calculate it when needed.
> This prepares for support of configurable APIC bus frequency by
> requiring to change only a single variable.
> 
> Suggested-by: Maxim Levitsky <maximlevitsky@xxxxxxxxx>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> Reviewed-by: Maxim Levitsky <maximlevitsky@xxxxxxxxx>
> Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> [reinette: rework changelog]
> Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>

Reviewed-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>