linux-kernel - Re: [PATCH v2 8/9] KVM: x86: lapic does not have to process INIT if it is blocked

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Date:   Wed, 17 Aug 2022 17:33:16 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Maxim Levitsky <mlevitsk@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        vkuznets@...hat.com
Subject: Re: [PATCH v2 8/9] KVM: x86: lapic does not have to process INIT if
 it is blocked

On 8/17/22 16:11, Maxim Levitsky wrote:
> 
> While reviwing this, I noticed that we have this code:
> 
> 
> static bool svm_apic_init_signal_blocked(struct kvm_vcpu *vcpu)
> {
>   struct vcpu_svm *svm = to_svm(vcpu);
> 
>   /*
>   * TODO: Last condition latch INIT signals on vCPU when
>   * vCPU is in guest-mode and vmcb12 defines intercept on INIT.
>   * To properly emulate the INIT intercept,
>   * svm_check_nested_events() should call nested_svm_vmexit()
>   * if an INIT signal is pending.
>   */
>   return !gif_set(svm) ||
>   (vmcb_is_intercept(&svm->vmcb->control, INTERCEPT_INIT));
> }
> 
> Is this workaround still needed? svm_check_nested_events does check
> the apic's INIT/SIPI status.
> 
> Currently the '.apic_init_signal_blocked' is called from
> kvm_vcpu_latch_init which itself is currently called from
> kvm_vcpu_latch_init which happens after we would vmexit if INIT is
> intercepted by nested hypervisor.
No, it shouldn't be needed anymore.

Paolo