KVM: x86: masking out upper bits

kvm_read_cr3() returns an unsigned long and gfn is a u64.  We intended
to mask out the bottom 5 bits but because of the type issue we mask the
top 32 bits as well.  I don't know if this is a real problem, but it
causes static checker warnings.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

arch/x86/kvm/x86.c

@@ -597,8 +597,8 @@ bool pdptrs_changed(struct kvm_vcpu *vcpu)
 		      (unsigned long *)&vcpu->arch.regs_avail))
 		return true;
 
-	gfn = (kvm_read_cr3(vcpu) & ~31u) >> PAGE_SHIFT;
-	offset = (kvm_read_cr3(vcpu) & ~31u) & (PAGE_SIZE - 1);
+	gfn = (kvm_read_cr3(vcpu) & ~31ul) >> PAGE_SHIFT;
+	offset = (kvm_read_cr3(vcpu) & ~31ul) & (PAGE_SIZE - 1);
 	r = kvm_read_nested_guest_page(vcpu, gfn, pdpte, offset, sizeof(pdpte),
 				       PFERR_USER_MASK | PFERR_WRITE_MASK);
 	if (r < 0)