KVM: x86: clear bus pointer when destroyed

commit df630b8c1e851b5e265dc2ca9c87222e342c093b upstream.

When releasing the bus, let's clear the bus pointers to mark it out. If
any further device unregister happens on this bus, we know that we're
done if we found the bus being released already.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e013f90f7a29a9d054d59a8d2b71a625b8e3f6c9..5f7bff5b9e4e9ad5dc7b32f33c1cc5ee66b48b93 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -614,8 +614,10 @@ 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);
@@ -3083,6 +3085,14 @@ int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
        struct kvm_io_bus *new_bus, *bus;
 
        bus = kvm->buses[bus_idx];
+
+       /*
+        * It's possible the bus being released before hand. If so,
+        * we're done here.
+        */
+       if (!bus)
+               return 0;
+
        r = -ENOENT;
        for (i = 0; i < bus->dev_count; i++)
                if (bus->range[i].dev == dev) {