From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
>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@xxxxxxxxxx>
Signed-off-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
---
arch/s390/include/asm/pgalloc.h | 3 +++
arch/s390/mm/pgtable.c | 48 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 590c321..e1408dd 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -22,6 +22,9 @@ unsigned long *page_table_alloc(struct mm_struct *, unsigned long);
void page_table_free(struct mm_struct *, unsigned long *);
void page_table_free_rcu(struct mmu_gather *, unsigned long *);
+int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
+ unsigned long key, bool nq);
+
static inline void clear_table(unsigned long *s, unsigned long val, size_t n)
{
typedef struct { char _[n]; } addrtype;
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 1e0c438..44b1450 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,
--
1.8.1.6
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