KVM: s390: Helper for converting real addresses to absolute

Added a separate helper function that translates guest real addresses
to guest absolute addresses by applying the prefix of the guest CPU.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 14 insertions, 7 deletions

diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h
index 99d789e8a018..374a439ccc60 100644
--- a/arch/s390/kvm/gaccess.h
+++ b/arch/s390/kvm/gaccess.h
@@ -18,20 +18,27 @@
 #include <asm/uaccess.h>
 #include "kvm-s390.h"
 
+/* Convert real to absolute address by applying the prefix of the CPU */
+static inline unsigned long kvm_s390_real_to_abs(struct kvm_vcpu *vcpu,
+                                                 unsigned long gaddr)
+{
+        unsigned long prefix  = vcpu->arch.sie_block->prefix;
+        if (gaddr < 2 * PAGE_SIZE)
+                gaddr += prefix;
+        else if (gaddr >= prefix && gaddr < prefix + 2 * PAGE_SIZE)
+                gaddr -= prefix;
+        return gaddr;
+}
+
 static inline void __user *__gptr_to_uptr(struct kvm_vcpu *vcpu,
                                           void __user *gptr,
                                           int prefixing)
 {
-        unsigned long prefix  = vcpu->arch.sie_block->prefix;
         unsigned long gaddr = (unsigned long) gptr;
         unsigned long uaddr;
 
-        if (prefixing) {
-                if (gaddr < 2 * PAGE_SIZE)
-                        gaddr += prefix;
-                else if ((gaddr >= prefix) && (gaddr < prefix + 2 * PAGE_SIZE))
-                        gaddr -= prefix;
-        }
+        if (prefixing)
+                gaddr = kvm_s390_real_to_abs(vcpu, gaddr);
         uaddr = gmap_fault(gaddr, vcpu->arch.gmap);
         if (IS_ERR_VALUE(uaddr))
                 uaddr = -EFAULT;