kvm: fix usage of uninit spinlock in avic_vm_destroy()

If avic is not enabled, avic_vm_init() does nothing and returns early.
However, avic_vm_destroy() still tries to destroy what hasn't been created.
The only bad consequence of this now is that avic_vm_destroy() uses
svm_vm_data_hash_lock that hasn't been initialized (and is not meant
to be used at all if avic is not enabled).

Return early from avic_vm_destroy() if avic is not enabled.
It has nothing to destroy.

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kvm@vger.kernel.org
Cc: syzkaller@googlegroups.com
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d1efe2c..5fba706 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1379,6 +1379,9 @@ static void avic_vm_destroy(struct kvm *kvm)
        unsigned long flags;
        struct kvm_arch *vm_data = &kvm->arch;
 
+       if (!avic)
+               return;
+
        avic_free_vm_id(vm_data->avic_vm_id);
 
        if (vm_data->avic_logical_id_table_page)