[PATCH 2/4] KVM: arm64: Don't serialize if the access flag isn't set

[Oliver Upton]

Of course, if the PTE wasn't changed then there are absolutely no
serialization requirements. Skip the DSB for an unsuccessful update to
the access flag.

Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
---
 arch/arm64/kvm/hyp/pgtable.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index b11cf2c618a6..9626f615d9b8 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1094,9 +1094,13 @@ int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
 kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
 {
 	kvm_pte_t pte = 0;
-	stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
-				 &pte, NULL, 0);
-	dsb(ishst);
+	int ret;
+
+	ret = stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
+				       &pte, NULL, 0);
+	if (!ret)
+		dsb(ishst);
+
 	return pte;
 }
 
-- 
2.38.1.584.g0f3c55d4c2-goog