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authorChristian Borntraeger <borntraeger@de.ibm.com>2013-05-27 10:42:04 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-06-26 21:10:04 +0200
commit24d5dd0208ed1cd3ef6bf30a50b347ef366f21ac (patch)
tree14d46de484f1297ce965e8b95a63ae167729a2fd /arch/s390/mm
parent25b41a7b67ee4f4d12cee8a4b8b5929e36c27e29 (diff)
s390/kvm: Provide function for setting the guest storage key
From time to time we need to set the guest storage key. Lets provide a helper function that handles the changes with all the right locking and checking. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/mm')
-rw-r--r--arch/s390/mm/pgtable.c48
1 files changed, 48 insertions, 0 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index a938b548f07e..74c29d922458 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -771,6 +771,54 @@ static inline void page_table_free_pgste(unsigned long *table)
__free_page(page);
}
+int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
+ unsigned long key, bool nq)
+{
+ spinlock_t *ptl;
+ pgste_t old, new;
+ pte_t *ptep;
+
+ down_read(&mm->mmap_sem);
+ ptep = get_locked_pte(current->mm, addr, &ptl);
+ if (unlikely(!ptep)) {
+ up_read(&mm->mmap_sem);
+ return -EFAULT;
+ }
+
+ new = old = pgste_get_lock(ptep);
+ pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |
+ PGSTE_ACC_BITS | PGSTE_FP_BIT);
+ pgste_val(new) |= (key & (_PAGE_CHANGED | _PAGE_REFERENCED)) << 48;
+ pgste_val(new) |= (key & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
+ if (!(pte_val(*ptep) & _PAGE_INVALID)) {
+ unsigned long address, bits;
+ unsigned char skey;
+
+ address = pte_val(*ptep) & PAGE_MASK;
+ skey = page_get_storage_key(address);
+ bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
+ /* Set storage key ACC and FP */
+ page_set_storage_key(address,
+ (key & (_PAGE_ACC_BITS | _PAGE_FP_BIT)),
+ !nq);
+
+ /* Merge host changed & referenced into pgste */
+ pgste_val(new) |= bits << 52;
+ /* Transfer skey changed & referenced bit to kvm user bits */
+ pgste_val(new) |= bits << 45; /* PGSTE_UR_BIT & PGSTE_UC_BIT */
+ }
+ /* changing the guest storage key is considered a change of the page */
+ if ((pgste_val(new) ^ pgste_val(old)) &
+ (PGSTE_ACC_BITS | PGSTE_FP_BIT | PGSTE_GR_BIT | PGSTE_GC_BIT))
+ pgste_val(new) |= PGSTE_UC_BIT;
+
+ pgste_set_unlock(ptep, new);
+ pte_unmap_unlock(*ptep, ptl);
+ up_read(&mm->mmap_sem);
+ return 0;
+}
+EXPORT_SYMBOL(set_guest_storage_key);
+
#else /* CONFIG_PGSTE */
static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,