linux-kernel - Re: [PATCH v2 2/3] KVM: x86: Provide TSC frequency in "generic" timing infomation CPUID leaf

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Message-ID: <aUHkTBzRqqvsG0LG@google.com>
Date: Tue, 16 Dec 2025 14:59:24 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Doug Covelli <doug.covelli@...adcom.com>
Cc: David Woodhouse <dwmw2@...radead.org>, Paolo Bonzini <pbonzini@...hat.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, graf@...zon.de, 
	Ajay Kaher <ajay.kaher@...adcom.com>, Alexey Makhalov <alexey.makhalov@...adcom.com>, 
	Colin Percival <cperciva@...snap.com>, Zack Rusin <zack.rusin@...adcom.com>
Subject: Re: [PATCH v2 2/3] KVM: x86: Provide TSC frequency in "generic"
 timing infomation CPUID leaf

On Tue, Dec 16, 2025, Doug Covelli wrote:
> On Tue, Dec 16, 2025 at 3:27 PM Sean Christopherson <seanjc@...gle.com> wrote:
> >
> > +Doug and Zach
> >
> > VMware folks, TL;DR question for you:
> >
> >   Does VMware report TSC and APIC bus frequency in CPUID 0x40000010.{EAX,EBX},
> >   or at the very least pinky swear not to use those outputs for anything else?
> 
> Yes, all 32-bits of 0x40000010.EAX is for TSC frequency and all
> 32-bits of 0x40000010.EBX is for APIC bus frequency.

Nice, thanks much for the confirmation and quick response!