Messages in this thread | | | Subject | Re: [v2 PATCH 3/4] x86/kvm: Add host side support for virtual suspend time injection | From | Paolo Bonzini <> | Date | Wed, 18 Aug 2021 22:49:05 +0200 |
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On 18/08/21 11:32, Vitaly Kuznetsov wrote: > On the host side, I'd vote for keeping MSR_KVM_ASYNC_PF_INT for async PF > mechanism only for two reasons: > - We may want to use (currently reserved) upper 56 bits of it for new > asyncPF related features (e.g. flags) and it would be unnatural to add > them to 'MSR_KVM_HYPERVISOR_CALLBACK_INT' > - We should probably leave it to the guest if it wants to share 'suspend > time' notification interrupt with async PF (and if it actually wants to > get one/another).
I agree that it's fine either way. That said, more MSRs are more complexity and more opportunity for getting things wrong (in either KVM or userspace---for example, migration). There are still 14 free bits in MSR_ASYNC_PF_EN (bits 63-52 and 5-4, so it should not be a problem to repurpose MSR_ASYNC_PF_INT.
Paolo
> On the guest side, it is perfectly fine to reuse > HYPERVISOR_CALLBACK_VECTOR for everything.
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