From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>,
Sean Christopherson <seanjc@google.com>
Cc: Anton Romanov <romanton@google.com>,
mtosatti@redhat.com, kvm@vger.kernel.org
Subject: Re: [PATCH v2] kvm: x86: Disable KVM_HC_CLOCK_PAIRING if tsc is in always catchup mode
Date: Thu, 17 Feb 2022 18:14:20 +0100 [thread overview]
Message-ID: <de6a1b73-c623-4776-2f14-b00917b7d22a@redhat.com> (raw)
In-Reply-To: <87pmnlpj8u.fsf@redhat.com>
On 2/17/22 17:09, Vitaly Kuznetsov wrote:
> 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).
It's not temporary, always-catchup is set on KVM_SET_TSC_KHZ and never
goes away.
Paolo
next prev parent reply other threads:[~2022-02-17 17:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-15 20:01 [PATCH v2] kvm: x86: Disable KVM_HC_CLOCK_PAIRING if tsc is in always catchup mode Anton Romanov
2022-02-16 14:14 ` Vitaly Kuznetsov
2022-02-17 15:41 ` Sean Christopherson
2022-02-17 16:09 ` Vitaly Kuznetsov
2022-02-17 17:14 ` Paolo Bonzini [this message]
2022-02-17 17:16 ` Vitaly Kuznetsov
2022-02-17 17:39 ` Paolo Bonzini
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