[RFC PATCH v4 06/13] iommu/io-pgtable-arm: Add and realize clear_dirty_log ops

[Keqian Zhu]

From: Kunkun Jiang <jiangkunkun at huawei.com>

After dirty log is retrieved, user should clear dirty log to re-enable
dirty log tracking for these dirtied pages. This clears the dirty state
(As we just set DBM bit for stage1 mapping, so should set the AP[2] bit)
of these leaf TTDs that are specified by the user provided bitmap.

Co-developed-by: Keqian Zhu <zhukeqian1 at huawei.com>
Signed-off-by: Kunkun Jiang <jiangkunkun at huawei.com>
---
 drivers/iommu/io-pgtable-arm.c | 93 ++++++++++++++++++++++++++++++++++
 include/linux/io-pgtable.h     |  4 ++
 2 files changed, 97 insertions(+)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 155d440099ab..2b41b9d0faa3 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -965,6 +965,98 @@ static int arm_lpae_sync_dirty_log(struct io_pgtable_ops *ops,
 					 bitmap, base_iova, bitmap_pgshift);
 }
 
+static int __arm_lpae_clear_dirty_log(struct arm_lpae_io_pgtable *data,
+				      unsigned long iova, size_t size,
+				      int lvl, arm_lpae_iopte *ptep,
+				      unsigned long *bitmap,
+				      unsigned long base_iova,
+				      unsigned long bitmap_pgshift)
+{
+	arm_lpae_iopte pte;
+	struct io_pgtable *iop = &data->iop;
+	unsigned long offset;
+	size_t base, next_size;
+	int nbits, ret, i;
+
+	if (WARN_ON(lvl == ARM_LPAE_MAX_LEVELS))
+		return -EINVAL;
+
+	ptep += ARM_LPAE_LVL_IDX(iova, lvl, data);
+	pte = READ_ONCE(*ptep);
+	if (WARN_ON(!pte))
+		return -EINVAL;
+
+	if (size == ARM_LPAE_BLOCK_SIZE(lvl, data)) {
+		if (iopte_leaf(pte, lvl, iop->fmt)) {
+			if (pte & ARM_LPAE_PTE_AP_RDONLY)
+				return 0;
+
+			/* Ensure all corresponding bits are set */
+			nbits = size >> bitmap_pgshift;
+			offset = (iova - base_iova) >> bitmap_pgshift;
+			for (i = offset; i < offset + nbits; i++) {
+				if (!test_bit(i, bitmap))
+					return 0;
+			}
+
+			/* Race does not exist */
+			pte |= ARM_LPAE_PTE_AP_RDONLY;
+			__arm_lpae_set_pte(ptep, pte, &iop->cfg);
+			return 0;
+		}
+		/* Current level is table, traverse next level */
+		next_size = ARM_LPAE_BLOCK_SIZE(lvl + 1, data);
+		ptep = iopte_deref(pte, data);
+		for (base = 0; base < size; base += next_size) {
+			ret = __arm_lpae_clear_dirty_log(data, iova + base,
+					next_size, lvl + 1, ptep, bitmap,
+					base_iova, bitmap_pgshift);
+			if (ret)
+				return ret;
+		}
+		return 0;
+	} else if (iopte_leaf(pte, lvl, iop->fmt)) {
+		/* Though the size is too small, it is already clean */
+		if (pte & ARM_LPAE_PTE_AP_RDONLY)
+			return 0;
+
+		return -EINVAL;
+	}
+
+	/* Keep on walkin */
+	ptep = iopte_deref(pte, data);
+	return __arm_lpae_clear_dirty_log(data, iova, size, lvl + 1, ptep,
+			bitmap, base_iova, bitmap_pgshift);
+}
+
+static int arm_lpae_clear_dirty_log(struct io_pgtable_ops *ops,
+				    unsigned long iova, size_t size,
+				    unsigned long *bitmap,
+				    unsigned long base_iova,
+				    unsigned long bitmap_pgshift)
+{
+	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
+	struct io_pgtable_cfg *cfg = &data->iop.cfg;
+	arm_lpae_iopte *ptep = data->pgd;
+	int lvl = data->start_level;
+	long iaext = (s64)iova >> cfg->ias;
+
+	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
+		return -EINVAL;
+
+	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1)
+		iaext = ~iaext;
+	if (WARN_ON(iaext))
+		return -EINVAL;
+
+	if (data->iop.fmt != ARM_64_LPAE_S1 &&
+	    data->iop.fmt != ARM_32_LPAE_S1)
+		return -EINVAL;
+
+	return __arm_lpae_clear_dirty_log(data, iova, size, lvl, ptep,
+			bitmap, base_iova, bitmap_pgshift);
+}
+
 static void arm_lpae_restrict_pgsizes(struct io_pgtable_cfg *cfg)
 {
 	unsigned long granule, page_sizes;
@@ -1046,6 +1138,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
 		.split_block	= arm_lpae_split_block,
 		.merge_page	= arm_lpae_merge_page,
 		.sync_dirty_log	= arm_lpae_sync_dirty_log,
+		.clear_dirty_log = arm_lpae_clear_dirty_log,
 	};
 
 	return data;
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 329fa99d9d96..4781407d5e2d 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -175,6 +175,10 @@ struct io_pgtable_ops {
 			      unsigned long iova, size_t size,
 			      unsigned long *bitmap, unsigned long base_iova,
 			      unsigned long bitmap_pgshift);
+	int (*clear_dirty_log)(struct io_pgtable_ops *ops,
+			       unsigned long iova, size_t size,
+			       unsigned long *bitmap, unsigned long base_iova,
+			       unsigned long bitmap_pgshift);
 };
 
 /**
-- 
2.19.1