[PULL 50/50] KVM: arm/arm64: vgic: Don't flush/sync without a working vgic

[Christoffer Dall]

If the vgic hasn't been created and initialized, we shouldn't attempt to
look at its data structures or flush/sync anything to the GIC hardware.

This fixes an issue reported by Alexander Graf when using a userspace
irqchip.

Fixes: 0919e84c0fc1 ("KVM: arm/arm64: vgic-new: Add IRQ sync/flush framework")
Cc: stable at vger.kernel.org
Reported-by: Alexander Graf <agraf at suse.de>
Acked-by: Marc Zyngier <marc.zyngier at arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
---
Note that this is rework of a patch submitted by Alexander Graf, but
slightly reworked to use vgic_initialized instead of vgic_enabled, as
discussed on the list.

 virt/kvm/arm/vgic/vgic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 8a529a7..2893d5b 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -645,6 +645,9 @@ next:
 /* Sync back the hardware VGIC state into our emulation after a guest's run. */
 void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 {
+	if (unlikely(!vgic_initialized(vcpu->kvm)))
+		return;
+
 	vgic_process_maintenance_interrupt(vcpu);
 	vgic_fold_lr_state(vcpu);
 	vgic_prune_ap_list(vcpu);
@@ -653,6 +656,9 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 /* Flush our emulation state into the GIC hardware before entering the guest. */
 void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 {
+	if (unlikely(!vgic_initialized(vcpu->kvm)))
+		return;
+
 	spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
 	vgic_flush_lr_state(vcpu);
 	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
-- 
2.9.0