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Re: [PATCH v3 36/41] x86/kvmclock: Get local APIC bus frequency from PV CPUID Timing Info
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- From: "Woodhouse, David" <dwmw@xxxxxxxxxxxx>
- Date: Wed, 20 May 2026 23:55:17 +0000
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- Thread-topic: [PATCH v3 36/41] x86/kvmclock: Get local APIC bus frequency from PV CPUID Timing Info
On Fri, 2026-05-15 at 12:19 -0700, Sean Christopherson wrote:
> When running as a KVM guest with kvmclock support enabled, stuff the APIC
> timer period/frequency with the local APIC bus frequency reported in
> CPUID.0x40000010.EBX instead of trying to calibrate/guess the frequency.
>
> See Documentation/virt/kvm/x86/cpuid.rst for details.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
I still don't much like the way this is done inside kvm_get_tsc_khz().
We also probably ought to be looking for the timing leaf on other
hypervisors including VMware and probably Bhyve too. Should it be done
somewhere else?
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