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SubjectRe: [kvm-devel] Guest kernel hangs in smp kvm for older kernels prior to tsc sync cleanup
Ingo Molnar wrote:
> * Avi Kivity <avi@qumranet.com> wrote:
>
>
>> Avi Kivity wrote:
>>
>>> Testing shows wrmsr and rdtsc function normally.
>>>
>>> I'll try pinning the vcpus to cpus and see if that helps.
>>>
>>>
>> It does.
>>
>
> do we let the guest read the physical CPU's TSC? That would be trouble.
>
>

vmx (and svm) allow us to add an offset to the physical tsc. We set it
on startup to -tsc (so that an rdtsc on boot would return 0), and
massage it on vcpu migration so that guest rdtsc is monotonic.

The net effect is that tsc on a vcpu can experience large forward jumps
and changes in rate, but no negative jumps.

--
error compiling committee.c: too many arguments to function



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