From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org,
linux-mm@kvack.org, David Hildenbrand <david@redhat.com>
Subject: [PATCH RFC 8/9] s390/mm: optimize set_guest_storage_key()
Date: Thu, 9 Sep 2021 16:59:44 +0200 [thread overview]
Message-ID: <20210909145945.12192-9-david@redhat.com> (raw)
In-Reply-To: <20210909145945.12192-1-david@redhat.com>
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(-)
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)) {
--
2.31.1
next prev parent reply other threads:[~2021-09-09 15:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-09 14:59 [PATCH RFC 0/9] s390: fixes, cleanups and optimizations for page table walkers David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 1/9] s390/gmap: validate VMA in __gmap_zap() David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 2/9] s390/gmap: don't unconditionally call pte_unmap_unlock() " David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 3/9] s390/mm: validate VMA in PGSTE manipulation functions David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 4/9] s390/mm: fix VMA and page table handling code in storage key handling functions David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 5/9] s390/uv: fully validate the VMA before calling follow_page() David Hildenbrand
2021-09-10 14:14 ` Liam Howlett
2021-09-09 14:59 ` [PATCH RFC 6/9] s390/pci_mmio: fully validate the VMA before calling follow_pte() David Hildenbrand
2021-09-10 8:22 ` Niklas Schnelle
2021-09-10 9:23 ` David Hildenbrand
2021-09-10 12:48 ` Niklas Schnelle
2021-09-10 14:12 ` Liam Howlett
2021-09-10 14:31 ` Niklas Schnelle
2021-09-10 14:52 ` Liam Howlett
2021-09-09 14:59 ` [PATCH RFC 7/9] s390/mm: no need for pte_alloc_map_lock() if we know the pmd is present David Hildenbrand
2021-09-09 14:59 ` David Hildenbrand [this message]
2021-09-09 14:59 ` [PATCH RFC 9/9] s390/mm: optimize reset_guest_reference_bit() David Hildenbrand
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