[PATCH] KVM: x86: WARN and fail kvm_set_irq() if a PIC or I/O APIC vector is invalid

[PATCH] KVM: x86: WARN and fail kvm_set_irq() if a PIC or I/O APIC vector is invalid

[Sean Christopherson]

WARN and return an error up the stack if the PIC or I/O APIC encounters an
invalid vector when injecting an IRQ, as there is no danger to the host and
thus no justification for potentially panicking the kernel.  Don't bug the
VM either, as the risk of corrupting the guest is minuscule, and the guest
might even be completely tolerant of a lost interrupt.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/i8259.c  | 3 ++-
 arch/x86/kvm/ioapic.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 59e28c45d7dc..6a942ac622d5 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -194,7 +194,8 @@ int kvm_pic_set_irq(struct kvm_kernel_irq_routing_entry *e, struct kvm *kvm,
 	int irq = e->irqchip.pin;
 	int ret, irq_level;
 
-	BUG_ON(irq < 0 || irq >= PIC_NUM_PINS);
+	if (WARN_ON_ONCE(irq < 0 || irq >= PIC_NUM_PINS))
+		return -1;
 
 	pic_lock(s);
 	irq_level = __kvm_irq_line_state(&s->irq_states[irq],
diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index f3f4a483ca15..88bd226f3b73 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -504,7 +504,8 @@ int kvm_ioapic_set_irq(struct kvm_kernel_irq_routing_entry *e, struct kvm *kvm,
 	int irq = e->irqchip.pin;
 	int ret, irq_level;
 
-	BUG_ON(irq < 0 || irq >= IOAPIC_NUM_PINS);
+	if (WARN_ON_ONCE(irq < 0 || irq >= IOAPIC_NUM_PINS))
+		return -1;
 
 	spin_lock(&ioapic->lock);
 	irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq],

base-commit: 9d4853b044beefa21c4ee3e18c40653601a64ced
-- 
2.55.0.rc0.738.g0c8ab3ebcc-goog

Re: [PATCH] KVM: x86: WARN and fail kvm_set_irq() if a PIC or I/O APIC vector is invalid

[Huang, Kai]

On Thu, 2026-06-18 at 11:52 -0700, Sean Christopherson wrote:
> WARN and return an error up the stack if the PIC or I/O APIC encounters an
> invalid vector when injecting an IRQ, as there is no danger to the host and
> thus no justification for potentially panicking the kernel.  Don't bug the
> VM either, as the risk of corrupting the guest is minuscule, and the guest
> might even be completely tolerant of a lost interrupt.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> 

Reviewed-by: Kai Huang <kai.huang@intel.com>

Re: [PATCH] KVM: x86: WARN and fail kvm_set_irq() if a PIC or I/O APIC vector is invalid

[Paolo Bonzini]

Queued, thanks.

Paolo