KVM: arm64: Introduce helper to retrieve a PTE and its level

It is becoming a common need to fetch the PTE for a given address
together with its level. Add such a helper.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210726153552.1535838-2-maz@kernel.org

1 files changed, 39 insertions, 0 deletions

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 05321f4165e3..78f36bd5df6c 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -326,6 +326,45 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
 	return _kvm_pgtable_walk(&walk_data);
 }
 
+struct leaf_walk_data {
+	kvm_pte_t	pte;
+	u32		level;
+};
+
+static int leaf_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
+		       enum kvm_pgtable_walk_flags flag, void * const arg)
+{
+	struct leaf_walk_data *data = arg;
+
+	data->pte   = *ptep;
+	data->level = level;
+
+	return 0;
+}
+
+int kvm_pgtable_get_leaf(struct kvm_pgtable *pgt, u64 addr,
+			 kvm_pte_t *ptep, u32 *level)
+{
+	struct leaf_walk_data data;
+	struct kvm_pgtable_walker walker = {
+		.cb	= leaf_walker,
+		.flags	= KVM_PGTABLE_WALK_LEAF,
+		.arg	= &data,
+	};
+	int ret;
+
+	ret = kvm_pgtable_walk(pgt, ALIGN_DOWN(addr, PAGE_SIZE),
+			       PAGE_SIZE, &walker);
+	if (!ret) {
+		if (ptep)
+			*ptep  = data.pte;
+		if (level)
+			*level = data.level;
+	}
+
+	return ret;
+}
+
 struct hyp_map_data {
 	u64				phys;
 	kvm_pte_t			attr;