kvm: mmu: extend the is_present check to 32 bits

This is safe because this function is called
on host controlled page table and non-present/non-MMIO
sptes never use bits 1..31. For the EPT case, this
ensures that cases where only the execute bit is set
is marked valid.
Signed-off-by: NBandan Das <bsd@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

@@ -304,7 +304,7 @@ static int is_nx(struct kvm_vcpu *vcpu)
 
 static int is_shadow_present_pte(u64 pte)
 {
-	return pte & PT_PRESENT_MASK && !is_mmio_spte(pte);
+	return (pte & 0xFFFFFFFFull) && !is_mmio_spte(pte);
 }
 
 static int is_large_pte(u64 pte)