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, 20 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index f004c0115d89..e42b55bd50a2 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -433,6 +433,26 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		     struct kvm_pgtable_walker *walker);
 
 /**
+ * kvm_pgtable_get_leaf() - Walk a page-table and retrieve the leaf entry
+ *			    with its level.
+ * @pgt:	Page-table structure initialised by kvm_pgtable_*_init()
+ *		or a similar initialiser.
+ * @addr:	Input address for the start of the walk.
+ * @ptep:	Pointer to storage for the retrieved PTE.
+ * @level:	Pointer to storage for the level of the retrieved PTE.
+ *
+ * The offset of @addr within a page is ignored.
+ *
+ * The walker will walk the page-table entries corresponding to the input
+ * address specified, retrieving the leaf corresponding to this address.
+ * Invalid entries are treated as leaf entries.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int kvm_pgtable_get_leaf(struct kvm_pgtable *pgt, u64 addr,
+			 kvm_pte_t *ptep, u32 *level);
+
+/**
  * kvm_pgtable_stage2_find_range() - Find a range of Intermediate Physical
  *				     Addresses with compatible permission
  *				     attributes.