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s390/mm: optimize set_guest_storage_key()

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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 set_guest_storage_key() to simply do nothing in case
the key to set is 0.

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/20210909162248.14969-9-david@redhat.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
David Hildenbrand 2021-09-09 18:22:47 +02:00 committed by Christian Borntraeger
parent 8318c404cf
commit 7cb70266b0
1 changed files with 12 additions and 2 deletions
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14
arch/s390/mm/pgtable.c
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@ -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)) {