s390/mm: return key via pointer in get_guest_storage_key

Let's just split returning the key and reporting errors. This makes calling
code easier and avoids bugs as happened already.

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 4c8d572d59cc..3e35298758d6 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -539,9 +539,9 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
 }
 EXPORT_SYMBOL(set_guest_storage_key);
 
-unsigned long get_guest_storage_key(struct mm_struct *mm, unsigned long addr)
+int get_guest_storage_key(struct mm_struct *mm, unsigned long addr,
+                          unsigned char *key)
 {
-        unsigned char key;
         spinlock_t *ptl;
         pgste_t pgste;
         pte_t *ptep;
@@ -551,14 +551,14 @@ unsigned long get_guest_storage_key(struct mm_struct *mm, unsigned long addr)
                 return -EFAULT;
 
         pgste = pgste_get_lock(ptep);
-        key = (pgste_val(pgste) & (PGSTE_ACC_BITS | PGSTE_FP_BIT)) >> 56;
+        *key = (pgste_val(pgste) & (PGSTE_ACC_BITS | PGSTE_FP_BIT)) >> 56;
         if (!(pte_val(*ptep) & _PAGE_INVALID))
-                key = page_get_storage_key(pte_val(*ptep) & PAGE_MASK);
+                *key = page_get_storage_key(pte_val(*ptep) & PAGE_MASK);
         /* Reflect guest's logical view, not physical */
-        key |= (pgste_val(pgste) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 48;
+        *key |= (pgste_val(pgste) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 48;
         pgste_set_unlock(ptep, pgste);
         pte_unmap_unlock(ptep, ptl);
-        return key;
+        return 0;
 }
 EXPORT_SYMBOL(get_guest_storage_key);
 #endif