[PATCH v2 1/3] KVM: arm64: Fix possible memory leak in kvm stage2

[Yanan Wang]

When installing a new leaf pte onto an invalid ptep, we need to
get_page(ptep). When just updating a valid leaf ptep, we shouldn't
get_page(ptep). Incorrect page_count of translation tables might 
lead to memory leak, when unmapping a stage 2 memory range.

Signed-off-by: Yanan Wang <wangyanan55 at huawei.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 0271b4a3b9fe..b232bdd142a6 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -470,6 +470,9 @@ static bool stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 	if (!kvm_block_mapping_supported(addr, end, phys, level))
 		return false;
 
+	if (kvm_pte_valid(*ptep))
+		put_page(virt_to_page(ptep));
+
 	if (kvm_set_valid_leaf_pte(ptep, phys, data->attr, level))
 		goto out;
 
-- 
2.19.1