From 7cb70266b0e3996daf4bbef9758b6e27e9ec904d Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 9 Sep 2021 18:22:47 +0200 Subject: s390/mm: optimize set_guest_storage_key() We already optimize get_guest_storage_key() to assume that if we don't have a PTE table and don't have a huge page mapped that the storage key is 0. Similarly, optimize set_guest_storage_key() to simply do nothing in case the key to set is 0. Signed-off-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Acked-by: Heiko Carstens Link: https://lore.kernel.org/r/20210909162248.14969-9-david@redhat.com Signed-off-by: Christian Borntraeger --- arch/s390/mm/pgtable.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'arch/s390/mm') diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index e74cc59dcd67..1c9aeb361f8d 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -792,13 +792,23 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp; pte_t *ptep; - if (pmd_lookup(mm, addr, &pmdp)) + /* + * If we don't have a PTE table and if there is no huge page mapped, + * we can ignore attempts to set the key to 0, because it already is 0. + */ + switch (pmd_lookup(mm, addr, &pmdp)) { + case -ENOENT: + return key ? -EFAULT : 0; + case 0: + break; + default: return -EFAULT; + } ptl = pmd_lock(mm, pmdp); if (!pmd_present(*pmdp)) { spin_unlock(ptl); - return -EFAULT; + return key ? -EFAULT : 0; } if (pmd_large(*pmdp)) { -- cgit v1.2.3-59-g8ed1b