[PATCH resend RFC 9/9] s390/mm: optimize reset_guest_reference_bit()
From: David Hildenbrand <hidden>
Date: 2021-09-09 16:24:24
Also in:
linux-mm, linux-s390, lkml
Subsystem:
s390 architecture, the rest · Maintainers:
Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds
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 <redacted> --- 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 534939a3eca5..50ab2fed3397 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)) {
--
2.31.1