KVM: Return if the pdptrs are invalid when the guest turns on PAE.

Don't fall through and turn on PAE in this case.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/kvm_main.c

@@ -558,6 +558,7 @@ void set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 		   && !load_pdptrs(vcpu, vcpu->cr3)) {
 		printk(KERN_DEBUG "set_cr4: #GP, pdptrs reserved bits\n");
 		inject_gp(vcpu);
+		return;
 	}
 
 	if (cr4 & X86_CR4_VMXE) {