linux-kernel - [PATCH v3 50/62] KVM: x86: WARN if IRQ bypass isn't supported in kvm_pi_update

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Message-ID: <20250611224604.313496-52-seanjc@google.com>
Date: Wed, 11 Jun 2025 15:45:53 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, Joerg Roedel <joro@...tes.org>, 
	David Woodhouse <dwmw2@...radead.org>, Lu Baolu <baolu.lu@...ux.intel.com>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, iommu@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	Sairaj Kodilkar <sarunkod@....com>, Vasant Hegde <vasant.hegde@....com>, 
	Maxim Levitsky <mlevitsk@...hat.com>, Joao Martins <joao.m.martins@...cle.com>, 
	Francesco Lavra <francescolavra.fl@...il.com>, David Matlack <dmatlack@...gle.com>
Subject: [PATCH v3 50/62] KVM: x86: WARN if IRQ bypass isn't supported in kvm_pi_update_irte()

WARN if kvm_pi_update_irte() is reached without IRQ bypass support, as the
code is only reachable if the VM already has an IRQ bypass producer (see
kvm_irq_routing_update()), or from kvm_arch_irq_bypass_{add,del}_producer(),
which, stating the obvious, are called if and only if KVM enables its IRQ
bypass hooks.

Cc: David Matlack <dmatlack@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/irq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
index 45cb9f1ee618..9c03a67fedbe 100644
--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -517,7 +517,7 @@ static int kvm_pi_update_irte(struct kvm_kernel_irqfd *irqfd,
 	struct kvm_lapic_irq irq;
 	int r;
 
-	if (!irqchip_in_kernel(kvm) || !kvm_arch_has_irq_bypass())
+	if (!irqchip_in_kernel(kvm) || WARN_ON_ONCE(!kvm_arch_has_irq_bypass()))
 		return 0;
 
 	if (entry && entry->type == KVM_IRQ_ROUTING_MSI) {
-- 
2.50.0.rc1.591.g9c95f17f64-goog