linux-kernel - Re: [PATCH 08/10] KVM: SVM: WARN if KVM attempts to create AVIC backing page with user APIC

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Date:   Thu, 05 Oct 2023 15:52:16 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Joerg Roedel <joro@...tes.org>
Cc:     kvm@...r.kernel.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/10] KVM: SVM: WARN if KVM attempts to create AVIC
 backing page with user APIC

У вт, 2023-08-15 у 14:35 -0700, Sean Christopherson пише:
> WARN if KVM attempts to allocate a vCPU's AVIC backing page without an
> in-kernel local APIC.  avic_init_vcpu() bails early if the APIC is not
> in-kernel, and KVM disallows enabling an in-kernel APIC after vCPUs have
> been created, i.e. it should be impossible to reach
> avic_init_backing_page() without the vAPIC being allocated.
> 
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/svm/avic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 522feaa711b4..3b2d00d9ca9b 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -300,7 +300,7 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu)
>  		return 0;
>  	}
>  
> -	if (!vcpu->arch.apic->regs)
> +	if (WARN_ON_ONCE(!vcpu->arch.apic->regs))
>  		return -EINVAL;
>  
>  	if (kvm_apicv_activated(vcpu->kvm)) {

As I said I prefer this to be folded with patch that adds the avic_init_backing_page().

Best regards,
	Maxim Levitsky