KVM: PPC: Deflect page write faults properly in kvmppc_st

When we have a page that we're not allowed to write to, xlate() will already
tell us -EPERM on lookup of that page. With the code as is we change it into
a "page missing" error which a guest may get confused about. Instead, just
tell the caller about the -EPERM directly.

This fixes Mac OS X guests when run with DCBZ32 emulation.
Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/kvm/book3s.c

@@ -418,11 +418,13 @@ int kvmppc_st(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr,
 	      bool data)
 {
 	struct kvmppc_pte pte;
+	int r;
 
 	vcpu->stat.st++;
 
-	if (kvmppc_xlate(vcpu, *eaddr, data, true, &pte))
-		return -ENOENT;
+	r = kvmppc_xlate(vcpu, *eaddr, data, true, &pte);
+	if (r < 0)
+		return r;
 
 	*eaddr = pte.raddr;