Re: [PATCH v4 08/17] kvm: x86: Introduce APICv pre-update hook

[Suravee Suthikulpanit]

Roman,

On 11/4/19 4:05 PM, Roman Kagan wrote:
> On Fri, Nov 01, 2019 at 10:41:31PM +0000, Suthikulpanit, Suravee wrote:
> > AMD SVM AVIC needs to update APIC backing page mapping before changing
> > APICv mode. Introduce struct kvm_x86_ops.pre_update_apicv_exec_ctrl
> > function hook to be called prior KVM APICv update request to each vcpu.
> This again seems to mix up APIC backing page and APIC access page.
>
> And I must be missing something obvious, but why is it necessary to
> unmap the APIC access page while AVIC is disabled?  Does keeping it
> around stand in the way when working with AVIC disabled?

I have replied to patch 07/17 with explanation.

Yes, keeping the APIC access page while disabling AVIC would cause
the SVM to not function properly.

Thanks,
Suravee

> Thanks,
> Roman.