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Re: [PATCH 01/16] x86/tsc: Add a standalone helpers for getting TSC info from CPUID.0x15
- To: Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, x86@xxxxxxxxxx, "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>, Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>, Wei Liu <wei.liu@xxxxxxxxxx>, Dexuan Cui <decui@xxxxxxxxxxxxx>, Ajay Kaher <ajay.kaher@xxxxxxxxxxxx>, Alexey Makhalov <alexey.amakhalov@xxxxxxxxxxxx>, Jan Kiszka <jan.kiszka@xxxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, linux-coco@xxxxxxxxxxxxxxx, virtualization@xxxxxxxxxxxxxxx, linux-hyperv@xxxxxxxxxxxxxxx, jailhouse-dev@xxxxxxxxxxxxxxxx, kvm@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, Nikunj A Dadhania <nikunj@xxxxxxx>, Tom Lendacky <thomas.lendacky@xxxxxxx>
- From: Sean Christopherson <seanjc@xxxxxxxxxx>
- Date: Wed, 5 Feb 2025 14:13:19 -0800
- Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
- Delivery-date: Wed, 05 Feb 2025 22:13:40 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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;
> +}
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