Re: [PATCH v2] kvm: x86: Disable KVM_HC_CLOCK_PAIRING if tsc is in always catchup mode

Vitaly Kuznetsov
2022-02-17T16:10:03Z

Sean Christopherson <seanjc@google.com> writes:

> On Wed, Feb 16, 2022, Vitaly Kuznetsov wrote:

...
>
>> Also, EOPNOTSUPP makes it sound like the hypercall is unsupported, I'd
>> suggest changing this to KVM_EFAULT.
>
> Eh, it's consistent with the above check though, where KVM returns KVM_EOPNOTSUPP
> due to the vclock mode being incompatible. This is more or less the same, it's
> just a different "mode". KVM_EFAULT suggests that the guest did something wrong
> and/or that the guest can remedy the problem in someway, e.g. by providing a
> different address. This issue is purely in the host's domain.

Ack, Paolo's already made the change back to KVM_EOPNOTSUPP upon commit
(but I still mildly dislike using 'EOPNOTSUPP' for a temporary condition
on the host).

--
Vitaly