diff options
Diffstat (limited to 'arch/s390/mm')
| -rw-r--r-- | arch/s390/mm/pgtable.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 3e35298758d6..e791e8b27fd2 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -539,6 +539,39 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr, } EXPORT_SYMBOL(set_guest_storage_key); +/** + * Conditionally set a guest storage key (handling csske). + * oldkey will be updated when either mr or mc is set and a pointer is given. + * + * Returns 0 if a guests storage key update wasn't necessary, 1 if the guest + * storage key was updated and -EFAULT on access errors. + */ +int cond_set_guest_storage_key(struct mm_struct *mm, unsigned long addr, + unsigned char key, unsigned char *oldkey, + bool nq, bool mr, bool mc) +{ + unsigned char tmp, mask = _PAGE_ACC_BITS | _PAGE_FP_BIT; + int rc; + + /* we can drop the pgste lock between getting and setting the key */ + if (mr | mc) { + rc = get_guest_storage_key(current->mm, addr, &tmp); + if (rc) + return rc; + if (oldkey) + *oldkey = tmp; + if (!mr) + mask |= _PAGE_REFERENCED; + if (!mc) + mask |= _PAGE_CHANGED; + if (!((tmp ^ key) & mask)) + return 0; + } + rc = set_guest_storage_key(current->mm, addr, key, nq); + return rc < 0 ? rc : 1; +} +EXPORT_SYMBOL(cond_set_guest_storage_key); + int get_guest_storage_key(struct mm_struct *mm, unsigned long addr, unsigned char *key) { |