Re: [PATCH v2 0/3] Support "generic" CPUID timing leaf as KVM guest and host

[Durrant, Paul]

On 29/08/2025, 10:51, "David Woodhouse" <dwmw2@xxxxxxxxxxxxx <mailto:dwmw2@xxxxxxxxxxxxx>> wrote:
[snip]
> • Declare that we don't care that it's strictly an ABI change, and
> VMMs which used to just populate the leaf and let KVM fill it in
> for Xen guests now *have* to use the new API.
> 
> 
> I'm actually OK with that, even the last one, because I've just noticed
> that KVM is updating the *wrong* Xen leaf. 0x40000x03/2 EAX is supposed
> to be the *host* TSC frequency, and the guest frequency is supposed to
> be in 0x40000x03/0 ECX. And Linux as a Xen guest doesn't even use it
> anyway, AFAICT
> 
> Paul, it was your code originally; are you happy with removing it?

Yes, if it is incorrect then please fix it. I must have become confused whilst reading the original Xen code. 

Cheers,

  Paul