From 14ea40e22c4193ed71cd93ec79c0c05216c3600a Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 9 Sep 2021 18:22:48 +0200 Subject: s390/mm: optimize reset_guest_reference_bit() 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 reset_guest_reference_bit() to simply do nothing if there is no PTE table and no huge page mapped. Signed-off-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Acked-by: Heiko Carstens Link: https://lore.kernel.org/r/20210909162248.14969-10-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 1c9aeb361f8d..c16232cd0ec5 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -901,13 +901,23 @@ int reset_guest_reference_bit(struct mm_struct *mm, unsigned long addr) pte_t *ptep; int cc = 0; - if (pmd_lookup(mm, addr, &pmdp)) + /* + * If we don't have a PTE table and if there is no huge page mapped, + * the storage key is 0 and there is nothing for us to do. + */ + switch (pmd_lookup(mm, addr, &pmdp)) { + case -ENOENT: + return 0; + case 0: + break; + default: return -EFAULT; + } ptl = pmd_lock(mm, pmdp); if (!pmd_present(*pmdp)) { spin_unlock(ptl); - return -EFAULT; + return 0; } if (pmd_large(*pmdp)) { -- cgit v1.2.3-59-g8ed1b