[PATCH v3 51/62] KVM: x86: WARN if IRQ bypass routing is updated without in-kernel local APIC

Sean Christopherson
2025-06-11T22:48:24Z

Yell if kvm_pi_update_irte() is reached without an in-kernel local APIC,
as kvm_arch_irqfd_allowed() should prevent attaching an irqfd and thus any
and all postable IRQs to an APIC-less VM.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/irq.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
index 9c03a67fedbe..02efa7162252 100644
--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -517,8 +517,8 @@ static int kvm_pi_update_irte(struct kvm_kernel_irqfd *irqfd,
struct kvm_lapic_irq irq;
int r;

- if (!irqchip_in_kernel(kvm) || WARN_ON_ONCE(!kvm_arch_has_irq_bypass()))
- return 0;
+ if (WARN_ON_ONCE(!irqchip_in_kernel(kvm) || !kvm_arch_has_irq_bypass()))
+ return -EINVAL;

if (entry && entry->type == KVM_IRQ_ROUTING_MSI) {
kvm_set_msi_irq(kvm, entry, &irq);
--
2.50.0.rc1.591.g9c95f17f64-goog