int x86_decode_emulated_instruction(struct kvm_vcpu *vcpu, int emulation_type,
				    void *insn, int insn_len)
{
	struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
	int r;

	init_emulate_ctxt(vcpu);

	r = x86_decode_insn(ctxt, insn, insn_len, emulation_type);

	trace_kvm_emulate_insn_start(vcpu);
	++vcpu->stat.insn_emulation;

	return r;
}
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.