KVM: s390: split kvm_s390_real_to_abs

A new function _kvm_s390_real_to_abs will apply prefixing to a real address
with a given prefix value.

The old kvm_s390_real_to_abs becomes now a wrapper around the new function.

This is needed to avoid code duplication in vSIE.
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210322140559.500716-2-imbrenda@linux.ibm.comSigned-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/gaccess.h

@@ -18,17 +18,14 @@
 
 /**
  * kvm_s390_real_to_abs - convert guest real address to guest absolute address
- * @vcpu - guest virtual cpu
+ * @prefix - guest prefix
  * @gra - guest real address
  *
  * Returns the guest absolute address that corresponds to the passed guest real
- * address @gra of a virtual guest cpu by applying its prefix.
+ * address @gra of by applying the given prefix.
  */
-static inline unsigned long kvm_s390_real_to_abs(struct kvm_vcpu *vcpu,
-						 unsigned long gra)
+static inline unsigned long _kvm_s390_real_to_abs(u32 prefix, unsigned long gra)
 {
-	unsigned long prefix  = kvm_s390_get_prefix(vcpu);
-
 	if (gra < 2 * PAGE_SIZE)
 		gra += prefix;
 	else if (gra >= prefix && gra < prefix + 2 * PAGE_SIZE)
@@ -36,6 +33,20 @@ static inline unsigned long kvm_s390_real_to_abs(struct kvm_vcpu *vcpu,
 	return gra;
 }
 
+/**
+ * kvm_s390_real_to_abs - convert guest real address to guest absolute address
+ * @vcpu - guest virtual cpu
+ * @gra - guest real address
+ *
+ * Returns the guest absolute address that corresponds to the passed guest real
+ * address @gra of a virtual guest cpu by applying its prefix.
+ */
+static inline unsigned long kvm_s390_real_to_abs(struct kvm_vcpu *vcpu,
+						 unsigned long gra)
+{
+	return _kvm_s390_real_to_abs(kvm_s390_get_prefix(vcpu), gra);
+}
+
 /**
  * _kvm_s390_logical_to_effective - convert guest logical to effective address
  * @psw: psw of the guest