linux-kernel - Re: [RFC PATCH v2 37/69] KVM: x86: Check for pending APICv interrupt in kvm_vcpu_has

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Date:   Tue, 6 Jul 2021 16:50:11 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     isaku.yamahata@...el.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     isaku.yamahata@...il.com,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [RFC PATCH v2 37/69] KVM: x86: Check for pending APICv interrupt
 in kvm_vcpu_has_events()

On 03/07/21 00:04, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
> 
> Return true for kvm_vcpu_has_events() if the vCPU has a pending APICv
> interrupt to support TDX's usage of APICv.  Unlike VMX, TDX doesn't have
> access to vmcs.GUEST_INTR_STATUS and so can't emulate posted interrupts,
> i.e. needs to generate a posted interrupt and more importantly can't
> manually move requested interrupts into the vIRR (which it also doesn't
> have access to).
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>   arch/x86/kvm/x86.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index f1d5e0a53640..92d5a6649a21 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -11341,7 +11341,9 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
>   
>   	if (kvm_arch_interrupt_allowed(vcpu) &&
>   	    (kvm_cpu_has_interrupt(vcpu) ||
> -	    kvm_guest_apic_has_interrupt(vcpu)))
> +	     kvm_guest_apic_has_interrupt(vcpu) ||
> +	     (vcpu->arch.apicv_active &&
> +	      kvm_x86_ops.dy_apicv_has_pending_interrupt(vcpu))))
>   		return true;
>   
>   	if (kvm_hv_has_stimer_pending(vcpu))
> 

Please remove "dy_" from the name of the callback, and use the static 
call.  Also, if it makes sense, please consider using the same test as 
for patch 38 to choose *between* either kvm_cpu_has_interrupt() + 
kvm_guest_apic_has_interrupt() or 
kvm_x86_ops.dy_apicv_has_pending_interrupt().

Paolo