linux-kernel - Re: [PATCH 01/16] x86/tsc: Add a standalone helpers for getting TSC info from CPUID.0x15

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] [day] [month] [year] [list]

Message-ID: <Z6Pif2CFE0o1eOnj@google.com>
Date: Wed, 5 Feb 2025 14:13:19 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: 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, 
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Juergen Gross <jgross@...e.com>, 
	"K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
	Dexuan Cui <decui@...rosoft.com>, Ajay Kaher <ajay.kaher@...adcom.com>, 
	Alexey Makhalov <alexey.amakhalov@...adcom.com>, Jan Kiszka <jan.kiszka@...mens.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Andy Lutomirski <luto@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, linux-kernel@...r.kernel.org, 
	linux-coco@...ts.linux.dev, virtualization@...ts.linux.dev, 
	linux-hyperv@...r.kernel.org, jailhouse-dev@...glegroups.com, 
	kvm@...r.kernel.org, xen-devel@...ts.xenproject.org, 
	Nikunj A Dadhania <nikunj@....com>, Tom Lendacky <thomas.lendacky@....com>
Cc: Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH 01/16] x86/tsc: Add a standalone helpers for getting TSC
 info from CPUID.0x15

On Fri, Jan 31, 2025, Sean Christopherson wrote:
> +static inline int cpuid_get_tsc_freq(unsigned int *tsc_khz,
> +				     unsigned int *crystal_khz)
> +{
> +	unsigned int denominator, numerator;
> +
> +	if (cpuid_get_tsc_info(tsc_khz, &denominator, &numerator))

As pointed out by Dan, this is broken.  It should be crystal_khz, not tsc_khz.
I fixed the bug in my test build but clobbered it before posting.

> +		return -ENOENT;
> +
> +	if (!*crystal_khz)
> +		return -ENOENT;
> +
> +	*tsc_khz = *crystal_khz * numerator / denominator;
> +	return 0;
> +}