Preparation to .map_page and .unmap_page removal

PATCH Superseded Leon Romanovsky 2 participants 5 messages Jul 20, 2025 DMA mapping helpers

Share & tools

Leon Romanovsky

author

2025-07-20 09:36 UTC #0 lore raw

cover Preparation to .map_page and .unmap_page removal

Changelog:
v1:
* 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        | 24 ++++++++++++++++++++----
 kernel/dma/ops_helpers.c    | 14 +++++++++++---
 4 files changed, 43 insertions(+), 14 deletions(-)

Signature · 1 line

2.50.1

Leon Romanovsky

author

2025-07-20 09:36 UTC #1 lore raw

PATCH 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        | 24 ++++++++++++++++++++----
 kernel/dma/ops_helpers.c    | 14 +++++++++++---
 3 files changed, 37 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 +20 -4

index 8d29ff76aa4db..bf700abe0a4fa 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 +187,11 @@ 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);
 	}
 
 	kmsan_handle_dma(phys, size, dir);

@@ -213,8 +221,16 @@ 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 +11 -3

index 6f9d604d9d406..64daa1428c022 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)

@@ -71,10 +72,14 @@ 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);
 	if (*dma_handle == DMA_MAPPING_ERROR) {

@@ -94,6 +99,9 @@ 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

kernel test robot

build bot

2025-07-20 11:29 UTC #2 lore raw

Re: [PATCH v1 1/2] dma-mapping: prepare dma_map_ops to conversion to physical address

kernel test robot noticed the following build warnings:

Hi Leon,

kernel test robot noticed the following build warnings:

[auto build test WARNING on next-20250718]
[cannot apply to linus/master v6.16-rc6 v6.16-rc5 v6.16-rc4 v6.16-rc6] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Leon-Romanovsky/dma-mapping-prepare-dma_map_ops-to-conversion-to-physical-address/20250720-173726
base:   next-20250718
patch link:    https://lore.kernel.org/r/184fc9bda626efc62c5022ace01a20b80d1dc93b.1753003879.git.leon%40kernel.org
patch subject: [PATCH v1 1/2] dma-mapping: prepare dma_map_ops to conversion to physical address
config: s390-randconfig-001-20250720 (https://download.01.org/0day-ci/archive/20250720/[email protected]/config)
compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project 16534d19bf50bde879a83f0ae62875e2c5120e64)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250720/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All warnings (new ones prefixed by >>):

>> kernel/dma/mapping.c:192:12: warning: variable 'addr' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     192 |                 else if (ops->map_page)
         |                          ^~~~~~~~~~~~~
   kernel/dma/mapping.c:198:32: note: uninitialized use occurs here
     198 |         trace_dma_map_phys(dev, phys, addr, size, dir, attrs);
         |                                       ^~~~
   kernel/dma/mapping.c:192:8: note: remove the 'if' if its condition is always true
     192 |                 else if (ops->map_page)
         |                      ^~~~~~~~~~~~~~~~~~
     193 |                         addr = ops->map_page(dev, page, offset, size, dir,
   kernel/dma/mapping.c:159:17: note: initialize the variable 'addr' to silence this warning
     159 |         dma_addr_t addr;
         |                        ^
         |                         = 0

1 warning generated.

vim +192 kernel/dma/mapping.c

154
155 dma_addr_t dma_map_phys(struct device *dev, phys_addr_t phys, size_t size,
156 enum dma_data_direction dir, unsigned long attrs)
157 {
158 const struct dma_map_ops *ops = get_dma_ops(dev);
159 dma_addr_t addr;
160
161 BUG_ON(!valid_dma_direction(dir));
162
163 if (WARN_ON_ONCE(!dev->dma_mask))
164 return DMA_MAPPING_ERROR;
165
166 if (dma_map_direct(dev, ops) ||
167 arch_dma_map_phys_direct(dev, phys + size))
168 addr = dma_direct_map_phys(dev, phys, size, dir, attrs);
169 else if (use_dma_iommu(dev))
170 addr = iommu_dma_map_phys(dev, phys, size, dir, attrs);
171 else {
172 struct page *page = phys_to_page(phys);
173 size_t offset = offset_in_page(phys);
174 bool is_pfn_valid = true;
175
176 if (IS_ENABLED(CONFIG_DMA_API_DEBUG)) {
177 is_pfn_valid = pfn_valid(PHYS_PFN(phys));
178
179 /* We shouldn't have both functions */
180 WARN_ON_ONCE(ops->map_page && ops->map_phys);
181 }
182
183 if (unlikely(!is_pfn_valid))
184 return DMA_MAPPING_ERROR;
185
186 /*
187 * All platforms which implement .map_page() don't support
188 * non-struct page backed addresses.
189 */
190 if (ops->map_phys)
191 addr = ops->map_phys(dev, phys, size, dir, attrs);

 > 192			else if (ops->map_page)

193 addr = ops->map_page(dev, page, offset, size, dir,
194 attrs);
195 }
196
197 kmsan_handle_dma(phys, size, dir);
198 trace_dma_map_phys(dev, phys, addr, size, dir, attrs);
199 debug_dma_map_phys(dev, phys, size, dir, addr, attrs);
200
201 return addr;
202 }
203 EXPORT_SYMBOL_GPL(dma_map_phys);
204

Signature · 2 lines

0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Leon Romanovsky

author

2025-07-20 13:10 UTC #3 lore raw

Re: [PATCH v1 1/2] dma-mapping: prepare dma_map_ops to conversion to physical address

Quoted 39 lines · kernel test robot

Hi Leon,
kernel test robot noticed the following build warnings:
[auto build test WARNING on next-20250718]
[cannot apply to linus/master v6.16-rc6 v6.16-rc5 v6.16-rc4 v6.16-rc6] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url:    https://github.com/intel-lab-lkp/linux/commits/Leon-Romanovsky/dma-mapping-prepare-dma_map_ops-to-conversion-to-physical-address/20250720-173726
base:   next-20250718
patch link:    https://lore.kernel.org/r/184fc9bda626efc62c5022ace01a20b80d1dc93b.1753003879.git.leon%40kernel.org
patch subject: [PATCH v1 1/2] dma-mapping: prepare dma_map_ops to conversion to physical address
config: s390-randconfig-001-20250720 (https://download.01.org/0day-ci/archive/20250720/[email protected]/config)
compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project 16534d19bf50bde879a83f0ae62875e2c5120e64)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250720/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All warnings (new ones prefixed by >>):
Quoted 1 line
Quoted 1 line
kernel/dma/mapping.c:192:12: warning: variable 'addr' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     192 |                 else if (ops->map_page)
         |                          ^~~~~~~~~~~~~
   kernel/dma/mapping.c:198:32: note: uninitialized use occurs here
     198 |         trace_dma_map_phys(dev, phys, addr, size, dir, attrs);
         |                                       ^~~~
   kernel/dma/mapping.c:192:8: note: remove the 'if' if its condition is always true
     192 |                 else if (ops->map_page)
         |                      ^~~~~~~~~~~~~~~~~~
     193 |                         addr = ops->map_page(dev, page, offset, size, dir,
   kernel/dma/mapping.c:159:17: note: initialize the variable 'addr' to silence this warning
     159 |         dma_addr_t addr;
         |                        ^
         |                         = 0

Quoted 1 line

1 warning generated.

Strange, I didn't get any warning about it for v1.

Thanks

Quoted 59 lines

vim +192 kernel/dma/mapping.c

   154	
   155	dma_addr_t dma_map_phys(struct device *dev, phys_addr_t phys, size_t size,
   156			enum dma_data_direction dir, unsigned long attrs)
   157	{
   158		const struct dma_map_ops *ops = get_dma_ops(dev);
   159		dma_addr_t addr;
   160	
   161		BUG_ON(!valid_dma_direction(dir));
   162	
   163		if (WARN_ON_ONCE(!dev->dma_mask))
   164			return DMA_MAPPING_ERROR;
   165	
   166		if (dma_map_direct(dev, ops) ||
   167		    arch_dma_map_phys_direct(dev, phys + size))
   168			addr = dma_direct_map_phys(dev, phys, size, dir, attrs);
   169		else if (use_dma_iommu(dev))
   170			addr = iommu_dma_map_phys(dev, phys, size, dir, attrs);
   171		else {
   172			struct page *page = phys_to_page(phys);
   173			size_t offset = offset_in_page(phys);
   174			bool is_pfn_valid = true;
   175	
   176			if (IS_ENABLED(CONFIG_DMA_API_DEBUG)) {
   177				is_pfn_valid = pfn_valid(PHYS_PFN(phys));
   178	
   179				/* We shouldn't have both functions */
   180				WARN_ON_ONCE(ops->map_page && ops->map_phys);
   181			}
   182	
   183			if (unlikely(!is_pfn_valid))
   184				return DMA_MAPPING_ERROR;
   185	
   186			/*
   187			 * All platforms which implement .map_page() don't support
   188			 * non-struct page backed addresses.
   189			 */
   190			if (ops->map_phys)
   191				addr = ops->map_phys(dev, phys, size, dir, attrs);

Quoted 1 line

192 else if (ops->map_page)

193 addr = ops->map_page(dev, page, offset, size, dir,

   194						     attrs);
   195		}
   196	
   197		kmsan_handle_dma(phys, size, dir);
   198		trace_dma_map_phys(dev, phys, addr, size, dir, attrs);
   199		debug_dma_map_phys(dev, phys, size, dir, addr, attrs);
   200	
   201		return addr;
   202	}
   203	EXPORT_SYMBOL_GPL(dma_map_phys);
   204

Signature · 2 lines

0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Leon Romanovsky

author

2025-07-20 09:36 UTC #4 lore raw

PATCH 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