Messages in this thread | | | Subject | Re: [PATCH v6 5/5] x86/kvm: Avoid dynamic allocation of pvclock data when SEV is active | From | Paolo Bonzini <> | Date | Tue, 11 Sep 2018 13:07:06 +0200 |
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On 11/09/2018 12:25, Borislav Petkov wrote: > On Tue, Sep 11, 2018 at 12:19:13PM +0200, Paolo Bonzini wrote: >> That's exactly what kvmclock is for, it provides a stable and >> synchronized clock on top of unsynchronized TSCs. But that's also why >> you need one struct per vCPU, at least in the synchronized case. ^^^^^^^^^^^^
unsynchronized
> > Why? > > Why can't it be a single pointer to a struct pvclock_vsyscall_time_info > shared between all vCPUs? > > Or does each vCPU write its own specific stuff into it so it has to be > per-vCPU?
If the host TSCs are unsynchronized then yes, that's what happens. And you can do live migration from synchronized to unsynchronized.
Paolo
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