Re: [PATCH v2] KVM: x86: check PIR even for vCPUs with disabled APICv

[Paolo Bonzini]

On 11/18/21 10:56, Maxim Levitsky wrote:
> vmx_sync_pir_to_irr has 'if (KVM_BUG_ON(!vcpu->arch.apicv_active,
> vcpu->kvm))' That has to be removed I think for this to work.

Good point.

> Plus the above calls now can happen when APICv is fully disabled (and
> not just inhibited), which is also something that I think that
> vmx_sync_pir_to_irr should be fixed to be aware of.

No, that works because sync_pir_to_irr is set to NULL as you point out 
below.  static_call sites are updated right after ops->hardware_setup(), 
in kvm_arch_hardware_setup.

Paolo

> Also note that VMX has code that sets vmx_x86_ops.sync_pir_to_irr to
> NULL in its 'hardware_setup' if APICv is disabled. I wonder if that
> done befor or after the static_call_cond sites are updated.
>
> I think that this code should be removed as well, and
> vmx_sync_pir_to_irr should just do nothing when APICv is fully
> disabled.