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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CADH9ctCEVJCC+_bZwDETmePhgfVy+jJvSb4Jz6bGLdmL9RSmUA@mail.gmail.com>
Date: Tue, 16 Dec 2025 16:10:14 -0500
From: Doug Covelli <doug.covelli@...adcom.com>
To: Sean Christopherson <seanjc@...gle.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 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.

Doug

Download attachment "smime.p7s" of type "application/pkcs7-signature" (5469 bytes)