linux-kernel - [PATCH 4.19 25/48] KVM: arm: vgic: Fix limit condition when writing to GICD

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Date:   Wed, 13 May 2020 11:44:51 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        André Przywara <andre.przywara@....com>,
        Marc Zyngier <maz@...nel.org>
Subject: [PATCH 4.19 25/48] KVM: arm: vgic: Fix limit condition when writing to GICD_I[CS]ACTIVER

From: Marc Zyngier <maz@...nel.org>

commit 1c32ca5dc6d00012f0c964e5fdd7042fcc71efb1 upstream.

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: stable@...r.kernel.org
Fixes: abd7229626b93 ("KVM: arm/arm64: Simplify active_change_prepare and plug race")
Reported-by: André Przywara <andre.przywara@....com>
Signed-off-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 virt/kvm/arm/vgic/vgic-mmio.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/virt/kvm/arm/vgic/vgic-mmio.c
+++ b/virt/kvm/arm/vgic/vgic-mmio.c
@@ -381,7 +381,7 @@ static void vgic_mmio_change_active(stru
 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);
 }
 
@@ -389,7 +389,7 @@ static void vgic_change_active_prepare(s
 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);
 }