From 71afaba4a2e98bb7bdeba5078370ab43d46e67a1 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@arm.com>
Date: Tue, 8 Jul 2014 12:09:00 +0100
Subject: [PATCH] KVM: ARM: vgic: plug irq injection race
As it stands, nothing prevents userspace from injecting an interrupt
before the guest's GIC is actually initialized.
This goes unnoticed so far (as everything is pretty much statically
allocated), but ends up exploding in a spectacular way once we switch
to a more dynamic allocation (the GIC data structure isn't there yet).
The fix is to test for the "ready" flag in the VGIC distributor before
trying to inject the interrupt. Note that in order to avoid breaking
userspace, we have to ignore what is essentially an error.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
---
virt/kvm/arm/vgic.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 37fd20d357594..9bdf181a00e22 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1585,7 +1585,8 @@ static bool vgic_update_irq_pending(struct kvm *kvm, int cpuid,
int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,
bool level)
{
- if (vgic_update_irq_pending(kvm, cpuid, irq_num, level))
+ if (likely(vgic_initialized(kvm)) &&
+ vgic_update_irq_pending(kvm, cpuid, irq_num, level))
vgic_kick_vcpus(kvm);
return 0;
--
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