Re: KVM timekeeping fixes, V2

Avi Kivity
2010-07-18T14:22:31Z

On 07/16/2010 10:26 PM, Joerg Roedel wrote:
> On Fri, Jul 16, 2010 at 07:20:32AM -1000, Zachary Amsden wrote:
>
>
>> I've been very careful to keep nested SVM safe, but I've not got a good
>> test for that. Is there any test suite for the nested case?
>>
> To test this you can boot a nested Linux guest and let both, L1 and L2
> guest use kvm_clock. Then put some load into the L2 guest and see if the
> L2 or the L1 freezes hard (which happens with kvm_clock when the TSC
> went backwards for one of them).
>
>

With recent guests, they won't freeze any more, since we detect the tsc
going backwards and compensate (in a brute-force way, nothing clever).

But you can printk the maximum compensation and see if it's something
unreasonable.

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