Paolo Bonzini <pbonz...@redhat.com> writes:

> On 26/09/19 08:23, Sergio Lopez wrote:
>> 
>> There's still one problem. If the Guest doesn't have TSC_DEADLINE_TIME,
>> Linux hangs on APIC timer calibration. I'm looking for a way to work
>> around this. Worst case scenario, we can check for that feature and add
>> both PIC and PIT if is missing.
>> 
>
> Huh, that's a silly thing that Linux is doing!  If KVM is in use, the
> LAPIC timer frequency is known to be 1 GHz.
>
> arch/x86/kernel/kvm.c can just set
>
>       lapic_timer_period = 1000000000 / HZ;
>
> and that should disabled LAPIC calibration if TSC deadline is absent.

Given that they can only be omitted when an specific set of conditions
is met, I think I'm going to make them optional but enabled by default.

I'll also point to this in the documentation.

Thanks,
Sergio

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