Preparation to .map_page and .unmap_page removal

PATCH Superseded Leon Romanovsky 1 participant 3 messages Jul 21, 2025 DMA mapping helpers

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Leon Romanovsky

author

2025-07-21 06:20 UTC #0 lore raw

v2 cover Preparation to .map_page and .unmap_page removal

Changelog:
v2:
* Added default "else" section without map_phys and map_page callbacks (impossible).
v1: https://lore.kernel.org/all/[email protected]
* Changed "else if" instead of "if".
v0: https://lore.kernel.org/all/[email protected]
---------------------------------------------------------------------

This is followup to "dma-mapping: migrate to physical address-based API" series https://lore.kernel.org/all/[email protected]/

These preparation changes are limited to DMA subsystem to avoid possible complications with submission to multiple trees.

Thanks

Leon Romanovsky (2):
dma-mapping: prepare dma_map_ops to conversion to physical address
dma-mapping: convert dummy ops to physical address mapping

 include/linux/dma-map-ops.h |  6 ++++++
 kernel/dma/dummy.c          | 13 ++++++-------
 kernel/dma/mapping.c        | 26 ++++++++++++++++++++++----
 kernel/dma/ops_helpers.c    | 17 ++++++++++++++---
 4 files changed, 48 insertions(+), 14 deletions(-)

Signature · 1 line

2.50.1

Leon Romanovsky

author

2025-07-21 06:20 UTC #1 lore raw

PATCH v2 1/2 dma-mapping: prepare dma_map_ops to conversion to physical address

From: Leon Romanovsky <[email protected]>

Add new .map_phys() and .unmap_phys() callbacks to dma_map_ops as a preparation to replace .map_page() and .unmap_page() respectively.

Signed-off-by Leon Romanovsky <[email protected]>

---
 include/linux/dma-map-ops.h |  6 ++++++
 kernel/dma/mapping.c        | 26 ++++++++++++++++++++++----
 kernel/dma/ops_helpers.c    | 17 ++++++++++++++---
 3 files changed, 42 insertions(+), 7 deletions(-)

include/linux/dma-map-ops.h +6 -0

index 71f5b30254159..0048ec28ed43b 100644
@@ -37,6 +37,12 @@ struct dma_map_ops {
 	void (*unmap_page)(struct device *dev, dma_addr_t dma_handle,
 			size_t size, enum dma_data_direction dir,
 			unsigned long attrs);
+	dma_addr_t (*map_phys)(struct device *dev, phys_addr_t phys,
+			size_t size, enum dma_data_direction dir,
+			unsigned long attrs);
+	void (*unmap_phys)(struct device *dev, dma_addr_t dma_handle,
+			size_t size, enum dma_data_direction dir,
+			unsigned long attrs);
 	/*
 	 * map_sg should return a negative error code on error. See
 	 * dma_map_sgtable() for a list of appropriate error codes

kernel/dma/mapping.c +22 -4

index 8d29ff76aa4db..c2400bf6f67d1 100644
@@ -173,9 +173,13 @@ dma_addr_t dma_map_phys(struct device *dev, phys_addr_t phys, size_t size,
 		size_t offset = offset_in_page(phys);
 		bool is_pfn_valid = true;
 
-		if (IS_ENABLED(CONFIG_DMA_API_DEBUG))
+		if (IS_ENABLED(CONFIG_DMA_API_DEBUG)) {
 			is_pfn_valid = pfn_valid(PHYS_PFN(phys));
 
+			/* We shouldn't have both functions */
+			WARN_ON_ONCE(ops->map_page && ops->map_phys);
+		}
+
 		if (unlikely(!is_pfn_valid))
 			return DMA_MAPPING_ERROR;

@@ -183,7 +187,13 @@ dma_addr_t dma_map_phys(struct device *dev, phys_addr_t phys, size_t size,
 		 * All platforms which implement .map_page() don't support
 		 * non-struct page backed addresses.
 		 */
-		addr = ops->map_page(dev, page, offset, size, dir, attrs);
+		if (ops->map_phys)
+			addr = ops->map_phys(dev, phys, size, dir, attrs);
+		else if (ops->map_page)
+			addr = ops->map_page(dev, page, offset, size, dir,
+					     attrs);
+		else
+			addr = DMA_MAPPING_ERROR;
 	}
 
 	kmsan_handle_dma(phys, size, dir);

@@ -213,8 +223,16 @@ void dma_unmap_phys(struct device *dev, dma_addr_t addr, size_t size,
 		dma_direct_unmap_phys(dev, addr, size, dir, attrs);
 	else if (use_dma_iommu(dev))
 		iommu_dma_unmap_phys(dev, addr, size, dir, attrs);
-	else
-		ops->unmap_page(dev, addr, size, dir, attrs);
+	else {
+		if (IS_ENABLED(CONFIG_DMA_API_DEBUG))
+			/* We shouldn't have both functions */
+			WARN_ON_ONCE(ops->unmap_page && ops->unmap_phys);
+
+		if (ops->unmap_phys)
+			ops->unmap_phys(dev, addr, size, dir, attrs);
+		else if (ops->unmap_page)
+			ops->unmap_page(dev, addr, size, dir, attrs);
+	}
 	trace_dma_unmap_phys(dev, addr, size, dir, attrs);
 	debug_dma_unmap_phys(dev, addr, size, dir);
 }

kernel/dma/ops_helpers.c +14 -3

index 6f9d604d9d406..84ce3a3ad7fd1 100644
@@ -64,6 +64,7 @@ struct page *dma_common_alloc_pages(struct device *dev, size_t size,
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 	struct page *page;
+	phys_addr_t phys;
 
 	page = dma_alloc_contiguous(dev, size, gfp);
 	if (!page)

@@ -71,12 +72,19 @@ struct page *dma_common_alloc_pages(struct device *dev, size_t size,
 	if (!page)
 		return NULL;
 
+	phys = page_to_phys(page);
 	if (use_dma_iommu(dev))
-		*dma_handle = iommu_dma_map_phys(dev, page_to_phys(page), size,
-						 dir, DMA_ATTR_SKIP_CPU_SYNC);
-	else
+		*dma_handle = iommu_dma_map_phys(dev, phys, size, dir,
+						 DMA_ATTR_SKIP_CPU_SYNC);
+	else if (ops->map_phys)
+		*dma_handle = ops->map_phys(dev, phys, size, dir,
+					    DMA_ATTR_SKIP_CPU_SYNC);
+	else if (ops->map_page)
 		*dma_handle = ops->map_page(dev, page, 0, size, dir,
 					    DMA_ATTR_SKIP_CPU_SYNC);
+	else
+		*dma_handle = DMA_MAPPING_ERROR;
+
 	if (*dma_handle == DMA_MAPPING_ERROR) {
 		dma_free_contiguous(dev, page, size);
 		return NULL;

@@ -94,6 +102,9 @@ void dma_common_free_pages(struct device *dev, size_t size, struct page *page,
 	if (use_dma_iommu(dev))
 		iommu_dma_unmap_phys(dev, dma_handle, size, dir,
 				     DMA_ATTR_SKIP_CPU_SYNC);
+	else if (ops->unmap_phys)
+		ops->unmap_phys(dev, dma_handle, size, dir,
+				DMA_ATTR_SKIP_CPU_SYNC);
 	else if (ops->unmap_page)
 		ops->unmap_page(dev, dma_handle, size, dir,
 				DMA_ATTR_SKIP_CPU_SYNC);

Signature · 1 line

2.50.1

Leon Romanovsky

author

2025-07-21 06:20 UTC #2 lore raw

PATCH v2 2/2 dma-mapping: convert dummy ops to physical address mapping

In reply to Leon Romanovsky

From: Leon Romanovsky <[email protected]>

Change dma_dummy_map_page and dma_dummy_unmap_page routines to accept physical address and rename them.

Signed-off-by Leon Romanovsky <[email protected]>

---
 kernel/dma/dummy.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

kernel/dma/dummy.c +6 -7

index 92de80e5b057e..dcc4c619b1389 100644
@@ -11,17 +11,16 @@ static int dma_dummy_mmap(struct device *dev, struct vm_area_struct *vma,
 	return -ENXIO;
 }
 
-static dma_addr_t dma_dummy_map_page(struct device *dev, struct page *page,
-		unsigned long offset, size_t size, enum dma_data_direction dir,
-		unsigned long attrs)
+static dma_addr_t dma_dummy_map_phys(struct device *dev, phys_addr_t phys,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
 {
 	return DMA_MAPPING_ERROR;
 }
-static void dma_dummy_unmap_page(struct device *dev, dma_addr_t dma_handle,
+static void dma_dummy_unmap_phys(struct device *dev, dma_addr_t dma_handle,
 		size_t size, enum dma_data_direction dir, unsigned long attrs)
 {
 	/*
-	 * Dummy ops doesn't support map_page, so unmap_page should never be
+	 * Dummy ops doesn't support map_phys, so unmap_phys should never be
 	 * called.
 	 */
 	WARN_ON_ONCE(true);

@@ -51,8 +50,8 @@ static int dma_dummy_supported(struct device *hwdev, u64 mask)
 
 const struct dma_map_ops dma_dummy_ops = {
 	.mmap                   = dma_dummy_mmap,
-	.map_page               = dma_dummy_map_page,
-	.unmap_page             = dma_dummy_unmap_page,
+	.map_phys               = dma_dummy_map_phys,
+	.unmap_phys             = dma_dummy_unmap_phys,
 	.map_sg                 = dma_dummy_map_sg,
 	.unmap_sg               = dma_dummy_unmap_sg,
 	.dma_supported          = dma_dummy_supported,

Signature · 1 line

2.50.1