Messages in this thread | | | Date | Wed, 19 Dec 2007 16:27:19 +0200 | From | Avi Kivity <> | Subject | Re: [kvm-devel] Guest kernel hangs in smp kvm for older kernels prior to tsc sync cleanup |
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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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