[PATCH 06/12] KVM: mark kvm->buses as empty once they were destroyed

[Andre Przywara]

In kvm_destroy_vm() we call kvm_io_bus_destroy() pretty early,
especially before calling kvm_arch_destroy_vm(). To avoid
unregistering devices from the already destroyed bus, let's mark
the bus with NULL to let other users know it has been destroyed
already.
This avoids a crash on a VM shutdown with the VGIC using the
kvm_io_bus later (the unregistering is in there to be able to roll
back a faulting init).

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
 virt/kvm/kvm_main.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8c7ab0b..6f164eb 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -604,8 +604,10 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	list_del(&kvm->vm_list);
 	spin_unlock(&kvm_lock);
 	kvm_free_irq_routing(kvm);
-	for (i = 0; i < KVM_NR_BUSES; i++)
+	for (i = 0; i < KVM_NR_BUSES; i++) {
 		kvm_io_bus_destroy(kvm->buses[i]);
+		kvm->buses[i] = NULL;
+	}
 	kvm_coalesced_mmio_free(kvm);
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
 	mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
-- 
1.7.9.5