Messages in this thread | | | From | Paul Durrant <> | Date | Wed, 1 Nov 2023 11:06:25 +0000 | Subject | Re: [PATCH v2] KVM x86/xen: add an override for PVCLOCK_TSC_STABLE_BIT |
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On 31/10/2023 23:06, David Woodhouse wrote: [snip] >> mutex_lock(&kvm->lock); >> if (!kvm->created_vcpus) { >> kvm->arch.force_tsc_unstable = true; >> r = 0; >> } >> mutex_unlock(&kvm->lock); >> >> So that it would be blatantly obvious that there's no race with checking a per-VM >> flag without any lock/RCU protections. > > Makes sense. Although TBH if the VMM wants to flip this bit on and off > at runtime while the guest clocks are being updated, it deserves what > it gets. It's not a problem for KVM. >
The first version of the patch that used an attribute requested a clock update when the attribute was set. I dropped that in this version but I think it'd best to re-instate it.
Paul
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