| Message ID | 20210909162248.14969-9-david@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | s390: fixes, cleanups and optimizations for page table walkers | expand |
On Thu, 9 Sep 2021 18:22:47 +0200 David Hildenbrand <david@redhat.com> wrote: > 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> > --- > arch/s390/mm/pgtable.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c > index 4e77b8ebdcc5..534939a3eca5 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)) {
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 4e77b8ebdcc5..534939a3eca5 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)) {
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> --- arch/s390/mm/pgtable.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)