iommu/io-pgtable-arm: Add way to debug pgtable walk

Add an io-pgtable method to walk the pgtable returning the raw PTEs that
would be traversed for a given iova access.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Mostafa Saleh <smostafa@google.com>
Link: https://lore.kernel.org/r/20241210165127.600817-4-robdclark@gmail.com
[will: Removed 'arm_lpae_io_pgtable_walk_data::level' per Mostafa]
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index dd2111731e19aaf3c36e4fc4fe3e9fd4883f1c59..7632c80edea63a3770c48884048d813aa42987de 100644 (file)
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -754,6 +754,28 @@ static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
        return iopte_to_paddr(d.pte, data) | iova;
 }
 
+static int visit_pgtable_walk(struct io_pgtable_walk_data *walk_data, int lvl,
+                             arm_lpae_iopte *ptep, size_t size)
+{
+       struct arm_lpae_io_pgtable_walk_data *data = walk_data->data;
+       data->ptes[lvl] = *ptep;
+       return 0;
+}
+
+static int arm_lpae_pgtable_walk(struct io_pgtable_ops *ops, unsigned long iova,
+                                void *wd)
+{
+       struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
+       struct io_pgtable_walk_data walk_data = {
+               .data = wd,
+               .visit = visit_pgtable_walk,
+               .addr = iova,
+               .end = iova + 1,
+       };
+
+       return __arm_lpae_iopte_walk(data, &walk_data, data->pgd, data->start_level);
+}
+
 static int io_pgtable_visit(struct arm_lpae_io_pgtable *data,
                            struct io_pgtable_walk_data *walk_data,
                            arm_lpae_iopte *ptep, int lvl)
@@ -929,6 +951,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
                .unmap_pages    = arm_lpae_unmap_pages,
                .iova_to_phys   = arm_lpae_iova_to_phys,
                .read_and_clear_dirty = arm_lpae_read_and_clear_dirty,
+               .pgtable_walk   = arm_lpae_pgtable_walk,
        };
 
        return data;

diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index ce86b09ae80f18374422c9e5a12b13190514443f..bba2a51c87d26f3555bcd4d9c0dd117c5582ca07 100644 (file)
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -180,12 +180,22 @@ struct io_pgtable_cfg {
        };
 };
 
+/**
+ * struct arm_lpae_io_pgtable_walk_data - information from a pgtable walk
+ *
+ * @ptes:     The recorded PTE values from the walk
+ */
+struct arm_lpae_io_pgtable_walk_data {
+       u64 ptes[4];
+};
+
 /**
  * struct io_pgtable_ops - Page table manipulation API for IOMMU drivers.
  *
  * @map_pages:    Map a physically contiguous range of pages of the same size.
  * @unmap_pages:  Unmap a range of virtually contiguous pages of the same size.
  * @iova_to_phys: Translate iova to physical address.
+ * @pgtable_walk: (optional) Perform a page table walk for a given iova.
  *
  * These functions map directly onto the iommu_ops member functions with
  * the same names.
@@ -199,6 +209,7 @@ struct io_pgtable_ops {
                              struct iommu_iotlb_gather *gather);
        phys_addr_t (*iova_to_phys)(struct io_pgtable_ops *ops,
                                    unsigned long iova);
+       int (*pgtable_walk)(struct io_pgtable_ops *ops, unsigned long iova, void *wd);
        int (*read_and_clear_dirty)(struct io_pgtable_ops *ops,
                                    unsigned long iova, size_t size,
                                    unsigned long flags,