Subject: [PATCH v2 1/6] KVM: arm: vgic: Fix limit condition when writing to GICD_I[CS]ACTIVER

From: Marc Zyngier <[email-masked]>
Date: Fri, 17 Apr 2020 09:33:14 +0100

When deciding whether a guest has to be stopped we check whether this
is a private interrupt or not. Unfortunately, there's an off-by-one bug
here, and we fail to recognize a whole range of interrupts as being
global (GICv2 SPIs 32-63).

Fix the condition from > to be >=.

Cc: [email-masked]
Fixes: abd7229626b93 ("KVM: arm/arm64: Simplify active_change_prepare and plug race")
Reported-by: André Przywara <[email-masked]>
Signed-off-by: Marc Zyngier <[email-masked]>
---
 virt/kvm/arm/vgic/vgic-mmio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
index 2199302597fa..d085e047953f 100644
--- a/virt/kvm/arm/vgic/vgic-mmio.c
+++ b/virt/kvm/arm/vgic/vgic-mmio.c
@@ -444,7 +444,7 @@ static void vgic_mmio_change_active(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
 static void vgic_change_active_prepare(struct kvm_vcpu *vcpu, u32 intid)
 {
 	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 ||
-	    intid > VGIC_NR_PRIVATE_IRQS)
+	    intid >= VGIC_NR_PRIVATE_IRQS)
 		kvm_arm_halt_guest(vcpu->kvm);
 }
 
@@ -452,7 +452,7 @@ static void vgic_change_active_prepare(struct kvm_vcpu *vcpu, u32 intid)
 static void vgic_change_active_finish(struct kvm_vcpu *vcpu, u32 intid)
 {
 	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 ||
-	    intid > VGIC_NR_PRIVATE_IRQS)
+	    intid >= VGIC_NR_PRIVATE_IRQS)
 		kvm_arm_resume_guest(vcpu->kvm);
 }
 
-- 
2.26.1

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