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s390/mm: optimize reset_guest_reference_bit()

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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 <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20210909162248.14969-10-david@redhat.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
David Hildenbrand 2021-09-09 18:22:48 +02:00 committed by Christian Borntraeger
parent 7cb70266b0
commit 14ea40e22c
1 changed files with 12 additions and 2 deletions
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14
arch/s390/mm/pgtable.c
View file

@ -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)) {