[PATCH v3 0/2] DMA IOMMU static calls

[PATCH v3 0/2] DMA IOMMU static calls

[Leon Romanovsky]

Changelog:
v3:
 * Changed coding style as Christoph asked
 * Moved debug WARN_ON check to dma_set_mask.
 * Slightly updated commit messages
 * Added Greg to the CC list
v2: https://lore.kernel.org/all/cover.1721219730.git.leon@kernel.org/
 * Ditched dma_ops flag in favor of field in struct device (suggested by
   Christoph)
 * Removed CONFIG_DMA_OPS select from dma-iommu.c Kconfig
 * Removed flags field which exist only in default IOMMU
v1: https://lore.kernel.org/all/cover.1721041611.git.leon@kernel.org/
 * Dropped extra layer and called directly to iommu_dma_* functions
 * Added unmap_page and unmap_sg to dummy ops
 * Converted all dma-mapping calls to use iommu directly
 * Updated commit messages
v0:
https://lore.kernel.org/all/98d1821780028434ff55b5d2f1feea287409fbc4.1720693745.git.leon@kernel.org/

Leon Romanovsky (2):
  dma: call unconditionally to unmap_page and unmap_sg callbacks
  dma: add IOMMU static calls with clear default ops

 MAINTAINERS                 |   1 +
 drivers/iommu/Kconfig       |   1 -
 drivers/iommu/dma-iommu.c   | 127 +++++++++++----------------
 include/linux/device.h      |   5 ++
 include/linux/dma-map-ops.h |  33 ++++---
 include/linux/iommu-dma.h   | 169 ++++++++++++++++++++++++++++++++++++
 kernel/dma/dummy.c          |  23 +++++
 kernel/dma/mapping.c        |  84 +++++++++++++++---
 8 files changed, 338 insertions(+), 105 deletions(-)
 create mode 100644 include/linux/iommu-dma.h

-- 
2.45.2

[PATCH v3 1/2] dma: call unconditionally to unmap_page and unmap_sg callbacks

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

Almost all users of ->map_page()/map_sg() callbacks implement
->unmap_page()/unmap_sg() callbacks too. One user which doesn't do it,
is dummy DMA ops interface, while the use of this interface is to fail
the operation. In such case, there won't be any call to ->unmap_page()/unmap_sg()
at all.

This patch removes the existence checks of ->unmap_page()/unmap_sg()
and calls to it directly to create symmetrical interface to
->map_page()/map_sg().

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 kernel/dma/dummy.c   | 23 +++++++++++++++++++++++
 kernel/dma/mapping.c |  4 ++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/kernel/dma/dummy.c b/kernel/dma/dummy.c
index b492d59ac77e..842deabae667 100644
--- a/kernel/dma/dummy.c
+++ b/kernel/dma/dummy.c
@@ -18,6 +18,17 @@ static dma_addr_t dma_dummy_map_page(struct device *dev, struct page *page,
 	return DMA_MAPPING_ERROR;
 }
 
+static void dma_dummy_unmap_page(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
+	 * called.
+	 */
+	WARN_ON_ONCE(true);
+}
+
 static int dma_dummy_map_sg(struct device *dev, struct scatterlist *sgl,
 		int nelems, enum dma_data_direction dir,
 		unsigned long attrs)
@@ -25,6 +36,16 @@ static int dma_dummy_map_sg(struct device *dev, struct scatterlist *sgl,
 	return -EINVAL;
 }
 
+static void dma_dummy_unmap_sg(struct device *dev, struct scatterlist *sgl,
+			       int nelems, enum dma_data_direction dir,
+			       unsigned long attrs)
+{
+	/*
+	 * Dummy ops doesn't support map_sg, so unmap_sg should never be called.
+	 */
+	WARN_ON_ONCE(true);
+}
+
 static int dma_dummy_supported(struct device *hwdev, u64 mask)
 {
 	return 0;
@@ -33,6 +54,8 @@ 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_sg                 = dma_dummy_map_sg,
+	.unmap_sg               = dma_dummy_unmap_sg,
 	.dma_supported          = dma_dummy_supported,
 };
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 81de84318ccc..6832fd6f0796 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -177,7 +177,7 @@ void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size,
 	if (dma_map_direct(dev, ops) ||
 	    arch_dma_unmap_page_direct(dev, addr + size))
 		dma_direct_unmap_page(dev, addr, size, dir, attrs);
-	else if (ops->unmap_page)
+	else
 		ops->unmap_page(dev, addr, size, dir, attrs);
 	debug_dma_unmap_page(dev, addr, size, dir);
 }
@@ -291,7 +291,7 @@ void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
 	if (dma_map_direct(dev, ops) ||
 	    arch_dma_unmap_sg_direct(dev, sg, nents))
 		dma_direct_unmap_sg(dev, sg, nents, dir, attrs);
-	else if (ops->unmap_sg)
+	else
 		ops->unmap_sg(dev, sg, nents, dir, attrs);
 }
 EXPORT_SYMBOL(dma_unmap_sg_attrs);
-- 
2.45.2

[PATCH v3 2/2] dma: add IOMMU static calls with clear default ops

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

Most of the arch DMA ops (which often, but not always, involve
some sort of IOMMU) are using the same DMA operations, but for all
modern platforms dma-iommu implementation is really matters.

So let's make sure to call them directly without need to perform function
pointers dereference.

During system initialization, the arch can set its own DMA and in such case,
the default DMA operations will be overridden.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 MAINTAINERS                 |   1 +
 drivers/iommu/Kconfig       |   1 -
 drivers/iommu/dma-iommu.c   | 127 +++++++++++----------------
 include/linux/device.h      |   5 ++
 include/linux/dma-map-ops.h |  33 ++++---
 include/linux/iommu-dma.h   | 169 ++++++++++++++++++++++++++++++++++++
 kernel/dma/mapping.c        |  84 +++++++++++++++---
 7 files changed, 315 insertions(+), 105 deletions(-)
 create mode 100644 include/linux/iommu-dma.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 958e935449e5..ce06c4df7e05 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11525,6 +11525,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux.git
 F:	Documentation/devicetree/bindings/iommu/
 F:	Documentation/userspace-api/iommu.rst
 F:	drivers/iommu/
+F:	include/linux/iommu-dma.h
 F:	include/linux/iommu.h
 F:	include/linux/iova.h
 F:	include/linux/of_iommu.h
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index c04584be3089..e0dd30c1b08a 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -151,7 +151,6 @@ config OF_IOMMU
 # IOMMU-agnostic DMA-mapping layer
 config IOMMU_DMA
 	def_bool ARM64 || X86 || S390
-	select DMA_OPS
 	select IOMMU_API
 	select IOMMU_IOVA
 	select IRQ_MSI_IOMMU
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 43520e7275cc..002e84c26c02 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -17,6 +17,7 @@
 #include <linux/gfp.h>
 #include <linux/huge_mm.h>
 #include <linux/iommu.h>
+#include <linux/iommu-dma.h>
 #include <linux/iova.h>
 #include <linux/irq.h>
 #include <linux/list_sort.h>
@@ -1039,9 +1040,9 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
 	return NULL;
 }
 
-static struct sg_table *iommu_dma_alloc_noncontiguous(struct device *dev,
-		size_t size, enum dma_data_direction dir, gfp_t gfp,
-		unsigned long attrs)
+struct sg_table *iommu_dma_alloc_noncontiguous(struct device *dev, size_t size,
+					       enum dma_data_direction dir,
+					       gfp_t gfp, unsigned long attrs)
 {
 	struct dma_sgt_handle *sh;
 
@@ -1058,8 +1059,9 @@ static struct sg_table *iommu_dma_alloc_noncontiguous(struct device *dev,
 	return &sh->sgt;
 }
 
-static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
-		struct sg_table *sgt, enum dma_data_direction dir)
+void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
+				  struct sg_table *sgt,
+				  enum dma_data_direction dir)
 {
 	struct dma_sgt_handle *sh = sgt_handle(sgt);
 
@@ -1069,8 +1071,8 @@ static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
 	kfree(sh);
 }
 
-static void iommu_dma_sync_single_for_cpu(struct device *dev,
-		dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
+void iommu_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
+				   size_t size, enum dma_data_direction dir)
 {
 	phys_addr_t phys;
 
@@ -1085,8 +1087,8 @@ static void iommu_dma_sync_single_for_cpu(struct device *dev,
 		swiotlb_sync_single_for_cpu(dev, phys, size, dir);
 }
 
-static void iommu_dma_sync_single_for_device(struct device *dev,
-		dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
+void iommu_dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle,
+				      size_t size, enum dma_data_direction dir)
 {
 	phys_addr_t phys;
 
@@ -1101,9 +1103,8 @@ static void iommu_dma_sync_single_for_device(struct device *dev,
 		arch_sync_dma_for_device(phys, size, dir);
 }
 
-static void iommu_dma_sync_sg_for_cpu(struct device *dev,
-		struct scatterlist *sgl, int nelems,
-		enum dma_data_direction dir)
+void iommu_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl,
+			       int nelems, enum dma_data_direction dir)
 {
 	struct scatterlist *sg;
 	int i;
@@ -1117,9 +1118,8 @@ static void iommu_dma_sync_sg_for_cpu(struct device *dev,
 			arch_sync_dma_for_cpu(sg_phys(sg), sg->length, dir);
 }
 
-static void iommu_dma_sync_sg_for_device(struct device *dev,
-		struct scatterlist *sgl, int nelems,
-		enum dma_data_direction dir)
+void iommu_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
+				  int nelems, enum dma_data_direction dir)
 {
 	struct scatterlist *sg;
 	int i;
@@ -1134,9 +1134,9 @@ static void iommu_dma_sync_sg_for_device(struct device *dev,
 			arch_sync_dma_for_device(sg_phys(sg), sg->length, dir);
 }
 
-static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
-		unsigned long offset, size_t size, enum dma_data_direction dir,
-		unsigned long attrs)
+dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
+			      unsigned long offset, size_t size,
+			      enum dma_data_direction dir, unsigned long attrs)
 {
 	phys_addr_t phys = page_to_phys(page) + offset;
 	bool coherent = dev_is_dma_coherent(dev);
@@ -1194,8 +1194,9 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 	return iova;
 }
 
-static void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
-		size_t size, enum dma_data_direction dir, unsigned long attrs)
+void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
+			  size_t size, enum dma_data_direction dir,
+			  unsigned long attrs)
 {
 	struct iommu_domain *domain = iommu_get_dma_domain(dev);
 	phys_addr_t phys;
@@ -1348,8 +1349,8 @@ static int iommu_dma_map_sg_swiotlb(struct device *dev, struct scatterlist *sg,
  * impedance-matching, to be able to hand off a suitably-aligned list,
  * but still preserve the original offsets and sizes for the caller.
  */
-static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
-		int nents, enum dma_data_direction dir, unsigned long attrs)
+int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
+		     enum dma_data_direction dir, unsigned long attrs)
 {
 	struct iommu_domain *domain = iommu_get_dma_domain(dev);
 	struct iommu_dma_cookie *cookie = domain->iova_cookie;
@@ -1468,8 +1469,8 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
 	return ret;
 }
 
-static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
-		int nents, enum dma_data_direction dir, unsigned long attrs)
+void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
+			enum dma_data_direction dir, unsigned long attrs)
 {
 	dma_addr_t end = 0, start;
 	struct scatterlist *tmp;
@@ -1518,16 +1519,18 @@ static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
 		__iommu_dma_unmap(dev, start, end - start);
 }
 
-static dma_addr_t iommu_dma_map_resource(struct device *dev, phys_addr_t phys,
-		size_t size, enum dma_data_direction dir, unsigned long attrs)
+dma_addr_t iommu_dma_map_resource(struct device *dev, phys_addr_t phys,
+				  size_t size, enum dma_data_direction dir,
+				  unsigned long attrs)
 {
 	return __iommu_dma_map(dev, phys, size,
 			dma_info_to_prot(dir, false, attrs) | IOMMU_MMIO,
 			dma_get_mask(dev));
 }
 
-static void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
-		size_t size, enum dma_data_direction dir, unsigned long attrs)
+void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
+			      size_t size, enum dma_data_direction dir,
+			      unsigned long attrs)
 {
 	__iommu_dma_unmap(dev, handle, size);
 }
@@ -1563,8 +1566,8 @@ static void __iommu_dma_free(struct device *dev, size_t size, void *cpu_addr)
 		dma_free_contiguous(dev, page, alloc_size);
 }
 
-static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
-		dma_addr_t handle, unsigned long attrs)
+void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
+		    dma_addr_t handle, unsigned long attrs)
 {
 	__iommu_dma_unmap(dev, handle, size);
 	__iommu_dma_free(dev, size, cpu_addr);
@@ -1607,8 +1610,8 @@ static void *iommu_dma_alloc_pages(struct device *dev, size_t size,
 	return NULL;
 }
 
-static void *iommu_dma_alloc(struct device *dev, size_t size,
-		dma_addr_t *handle, gfp_t gfp, unsigned long attrs)
+void *iommu_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
+		      gfp_t gfp, unsigned long attrs)
 {
 	bool coherent = dev_is_dma_coherent(dev);
 	int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
@@ -1642,9 +1645,9 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
 	return cpu_addr;
 }
 
-static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
-		void *cpu_addr, dma_addr_t dma_addr, size_t size,
-		unsigned long attrs)
+int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
+		   void *cpu_addr, dma_addr_t dma_addr, size_t size,
+		   unsigned long attrs)
 {
 	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	unsigned long pfn, off = vma->vm_pgoff;
@@ -1673,9 +1676,9 @@ static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 			       vma->vm_page_prot);
 }
 
-static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
-		void *cpu_addr, dma_addr_t dma_addr, size_t size,
-		unsigned long attrs)
+int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
+			  void *cpu_addr, dma_addr_t dma_addr, size_t size,
+			  unsigned long attrs)
 {
 	struct page *page;
 	int ret;
@@ -1700,19 +1703,19 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
 	return ret;
 }
 
-static unsigned long iommu_dma_get_merge_boundary(struct device *dev)
+unsigned long iommu_dma_get_merge_boundary(struct device *dev)
 {
 	struct iommu_domain *domain = iommu_get_dma_domain(dev);
 
 	return (1UL << __ffs(domain->pgsize_bitmap)) - 1;
 }
 
-static size_t iommu_dma_opt_mapping_size(void)
+size_t iommu_dma_opt_mapping_size(void)
 {
 	return iova_rcache_range();
 }
 
-static size_t iommu_dma_max_mapping_size(struct device *dev)
+size_t iommu_dma_max_mapping_size(struct device *dev)
 {
 	if (dev_is_untrusted(dev))
 		return swiotlb_max_mapping_size(dev);
@@ -1720,32 +1723,6 @@ static size_t iommu_dma_max_mapping_size(struct device *dev)
 	return SIZE_MAX;
 }
 
-static const struct dma_map_ops iommu_dma_ops = {
-	.flags			= DMA_F_PCI_P2PDMA_SUPPORTED |
-				  DMA_F_CAN_SKIP_SYNC,
-	.alloc			= iommu_dma_alloc,
-	.free			= iommu_dma_free,
-	.alloc_pages_op		= dma_common_alloc_pages,
-	.free_pages		= dma_common_free_pages,
-	.alloc_noncontiguous	= iommu_dma_alloc_noncontiguous,
-	.free_noncontiguous	= iommu_dma_free_noncontiguous,
-	.mmap			= iommu_dma_mmap,
-	.get_sgtable		= iommu_dma_get_sgtable,
-	.map_page		= iommu_dma_map_page,
-	.unmap_page		= iommu_dma_unmap_page,
-	.map_sg			= iommu_dma_map_sg,
-	.unmap_sg		= iommu_dma_unmap_sg,
-	.sync_single_for_cpu	= iommu_dma_sync_single_for_cpu,
-	.sync_single_for_device	= iommu_dma_sync_single_for_device,
-	.sync_sg_for_cpu	= iommu_dma_sync_sg_for_cpu,
-	.sync_sg_for_device	= iommu_dma_sync_sg_for_device,
-	.map_resource		= iommu_dma_map_resource,
-	.unmap_resource		= iommu_dma_unmap_resource,
-	.get_merge_boundary	= iommu_dma_get_merge_boundary,
-	.opt_mapping_size	= iommu_dma_opt_mapping_size,
-	.max_mapping_size       = iommu_dma_max_mapping_size,
-};
-
 void iommu_setup_dma_ops(struct device *dev)
 {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
@@ -1753,19 +1730,15 @@ void iommu_setup_dma_ops(struct device *dev)
 	if (dev_is_pci(dev))
 		dev->iommu->pci_32bit_workaround = !iommu_dma_forcedac;
 
-	if (iommu_is_dma_domain(domain)) {
-		if (iommu_dma_init_domain(domain, dev))
-			goto out_err;
-		dev->dma_ops = &iommu_dma_ops;
-	} else if (dev->dma_ops == &iommu_dma_ops) {
-		/* Clean up if we've switched *from* a DMA domain */
-		dev->dma_ops = NULL;
-	}
+	dev->dma_iommu = iommu_is_dma_domain(domain);
+	if (dev->dma_iommu && iommu_dma_init_domain(domain, dev))
+		goto out_err;
 
 	return;
 out_err:
-	 pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
-		 dev_name(dev));
+	pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
+		dev_name(dev));
+	dev->dma_iommu = false;
 }
 
 static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
diff --git a/include/linux/device.h b/include/linux/device.h
index ace039151cb8..e66ec47ceb09 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -707,6 +707,8 @@ struct device_physical_location {
  *		for dma allocations.  This flag is managed by the dma ops
  *		instance from ->dma_supported.
  * @dma_skip_sync: DMA sync operations can be skipped for coherent buffers.
+ * @dma_iommu: Device is using default IOMMU implementation for DMA and
+ *		doesn't rely on dma_ops structure.
  *
  * At the lowest level, every device in a Linux system is represented by an
  * instance of struct device. The device structure contains the information
@@ -822,6 +824,9 @@ struct device {
 #ifdef CONFIG_DMA_NEED_SYNC
 	bool			dma_skip_sync:1;
 #endif
+#ifdef CONFIG_IOMMU_DMA
+	bool			dma_iommu : 1;
+#endif
 };
 
 /**
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 02a1c825896b..a301433a3d5f 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -13,20 +13,7 @@
 struct cma;
 struct iommu_ops;
 
-/*
- * Values for struct dma_map_ops.flags:
- *
- * DMA_F_PCI_P2PDMA_SUPPORTED: Indicates the dma_map_ops implementation can
- * handle PCI P2PDMA pages in the map_sg/unmap_sg operation.
- * DMA_F_CAN_SKIP_SYNC: DMA sync operations can be skipped if the device is
- * coherent and it's not an SWIOTLB buffer.
- */
-#define DMA_F_PCI_P2PDMA_SUPPORTED     (1 << 0)
-#define DMA_F_CAN_SKIP_SYNC            (1 << 1)
-
 struct dma_map_ops {
-	unsigned int flags;
-
 	void *(*alloc)(struct device *dev, size_t size,
 			dma_addr_t *dma_handle, gfp_t gfp,
 			unsigned long attrs);
@@ -103,6 +90,10 @@ static inline void set_dma_ops(struct device *dev,
 {
 	dev->dma_ops = dma_ops;
 }
+struct page *dma_common_alloc_pages(struct device *dev, size_t size,
+		dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp);
+void dma_common_free_pages(struct device *dev, size_t size, struct page *vaddr,
+		dma_addr_t dma_handle, enum dma_data_direction dir);
 #else /* CONFIG_DMA_OPS */
 static inline const struct dma_map_ops *get_dma_ops(struct device *dev)
 {
@@ -112,6 +103,18 @@ static inline void set_dma_ops(struct device *dev,
 			       const struct dma_map_ops *dma_ops)
 {
 }
+static inline struct page *
+dma_common_alloc_pages(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		       enum dma_data_direction dir, gfp_t gfp)
+{
+	return NULL;
+}
+static inline void dma_common_free_pages(struct device *dev, size_t size,
+					 struct page *vaddr,
+					 dma_addr_t dma_handle,
+					 enum dma_data_direction dir)
+{
+}
 #endif /* CONFIG_DMA_OPS */
 
 #ifdef CONFIG_DMA_CMA
@@ -239,10 +242,6 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
 int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs);
-struct page *dma_common_alloc_pages(struct device *dev, size_t size,
-		dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp);
-void dma_common_free_pages(struct device *dev, size_t size, struct page *vaddr,
-		dma_addr_t dma_handle, enum dma_data_direction dir);
 
 struct page **dma_common_find_pages(void *cpu_addr);
 void *dma_common_contiguous_remap(struct page *page, size_t size, pgprot_t prot,
diff --git a/include/linux/iommu-dma.h b/include/linux/iommu-dma.h
new file mode 100644
index 000000000000..622232fc9510
--- /dev/null
+++ b/include/linux/iommu-dma.h
@@ -0,0 +1,169 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved
+ *
+ * DMA operations that map physical memory through IOMMU.
+ */
+#ifndef _LINUX_IOMMU_DMA_H
+#define _LINUX_IOMMU_DMA_H
+
+#include <linux/dma-direction.h>
+
+#ifdef CONFIG_IOMMU_DMA
+dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
+			      unsigned long offset, size_t size,
+			      enum dma_data_direction dir, unsigned long attrs);
+void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
+			  size_t size, enum dma_data_direction dir,
+			  unsigned long attrs);
+int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
+		     enum dma_data_direction dir, unsigned long attrs);
+void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
+			enum dma_data_direction dir, unsigned long attrs);
+void *iommu_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
+		      gfp_t gfp, unsigned long attrs);
+int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
+		   void *cpu_addr, dma_addr_t dma_addr,
+		   size_t size, unsigned long attrs);
+int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
+			  void *cpu_addr, dma_addr_t dma_addr, size_t size,
+			  unsigned long attrs);
+unsigned long iommu_dma_get_merge_boundary(struct device *dev);
+size_t iommu_dma_opt_mapping_size(void);
+size_t iommu_dma_max_mapping_size(struct device *dev);
+void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
+		    dma_addr_t handle, unsigned long attrs);
+dma_addr_t iommu_dma_map_resource(struct device *dev, phys_addr_t phys,
+				  size_t size, enum dma_data_direction dir,
+				  unsigned long attrs);
+void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
+			      size_t size, enum dma_data_direction dir,
+			      unsigned long attrs);
+struct sg_table *iommu_dma_alloc_noncontiguous(struct device *dev, size_t size,
+					       enum dma_data_direction dir,
+					       gfp_t gfp, unsigned long attrs);
+void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
+				  struct sg_table *sgt,
+				  enum dma_data_direction dir);
+void iommu_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
+				   size_t size, enum dma_data_direction dir);
+void iommu_dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle,
+				      size_t size, enum dma_data_direction dir);
+void iommu_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl,
+			       int nelems, enum dma_data_direction dir);
+void iommu_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
+				  int nelems, enum dma_data_direction dir);
+#else
+static inline dma_addr_t iommu_dma_map_page(struct device *dev,
+					    struct page *page,
+					    unsigned long offset, size_t size,
+					    enum dma_data_direction dir,
+					    unsigned long attrs)
+{
+	return DMA_MAPPING_ERROR;
+}
+static inline void iommu_dma_unmap_page(struct device *dev,
+					dma_addr_t dma_handle, size_t size,
+					enum dma_data_direction dir,
+					unsigned long attrs)
+{
+}
+static inline int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
+				   int nents, enum dma_data_direction dir,
+				   unsigned long attrs)
+{
+	return -EINVAL;
+}
+static inline void iommu_dma_unmap_sg(struct device *dev,
+				      struct scatterlist *sg, int nents,
+				      enum dma_data_direction dir,
+				      unsigned long attrs)
+{
+}
+static inline void *iommu_dma_alloc(struct device *dev, size_t size,
+				    dma_addr_t *handle, gfp_t gfp,
+				    unsigned long attrs)
+{
+	return NULL;
+}
+static inline int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
+				 void *cpu_addr, dma_addr_t dma_addr,
+				 size_t size, unsigned long attrs)
+{
+	return -EINVAL;
+}
+static inline int iommu_dma_get_sgtable(struct device *dev,
+					struct sg_table *sgt, void *cpu_addr,
+					dma_addr_t dma_addr, size_t size,
+					unsigned long attrs)
+{
+	return -EINVAL;
+}
+static inline unsigned long iommu_dma_get_merge_boundary(struct device *dev)
+{
+	return 0;
+}
+static inline size_t iommu_dma_opt_mapping_size(void)
+{
+	return 0;
+}
+static inline size_t iommu_dma_max_mapping_size(struct device *dev)
+{
+	return 0;
+}
+static inline void iommu_dma_free(struct device *dev, size_t size,
+				  void *cpu_addr, dma_addr_t handle,
+				  unsigned long attrs)
+{
+}
+static inline dma_addr_t iommu_dma_map_resource(struct device *dev,
+						phys_addr_t phys, size_t size,
+						enum dma_data_direction dir,
+						unsigned long attrs)
+{
+	return DMA_MAPPING_ERROR;
+}
+static inline void iommu_dma_unmap_resource(struct device *dev,
+					    dma_addr_t handle, size_t size,
+					    enum dma_data_direction dir,
+					    unsigned long attrs)
+{
+}
+static inline struct sg_table *
+iommu_dma_alloc_noncontiguous(struct device *dev, size_t size,
+			      enum dma_data_direction dir, gfp_t gfp,
+			      unsigned long attrs)
+{
+	return NULL;
+}
+static inline void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
+						struct sg_table *sgt,
+						enum dma_data_direction dir)
+{
+}
+static inline void iommu_dma_sync_single_for_cpu(struct device *dev,
+						 dma_addr_t dma_handle,
+						 size_t size,
+						 enum dma_data_direction dir)
+{
+}
+static inline void iommu_dma_sync_single_for_device(struct device *dev,
+						    dma_addr_t dma_handle,
+						    size_t size,
+						    enum dma_data_direction dir)
+{
+}
+static inline void iommu_dma_sync_sg_for_cpu(struct device *dev,
+					     struct scatterlist *sgl,
+					     int nelems,
+					     enum dma_data_direction dir)
+{
+}
+static inline void iommu_dma_sync_sg_for_device(struct device *dev,
+						struct scatterlist *sgl,
+						int nelems,
+						enum dma_data_direction dir)
+{
+}
+#endif /* CONFIG_IOMMU_DMA */
+#endif /* _LINUX_IOMMU_DMA_H */
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 6832fd6f0796..f20fef7728f9 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -8,6 +8,7 @@
 #include <linux/memblock.h> /* for max_pfn */
 #include <linux/acpi.h>
 #include <linux/dma-map-ops.h>
+#include <linux/iommu-dma.h>
 #include <linux/export.h>
 #include <linux/gfp.h>
 #include <linux/kmsan.h>
@@ -113,11 +114,27 @@ void *dmam_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
 }
 EXPORT_SYMBOL(dmam_alloc_attrs);
 
+#ifdef CONFIG_IOMMU_DMA
+static bool use_dma_iommu(struct device *dev)
+{
+	return dev->dma_iommu;
+}
+#else
+static bool use_dma_iommu(struct device *dev)
+{
+	return false;
+}
+#endif
+
 static bool dma_go_direct(struct device *dev, dma_addr_t mask,
 		const struct dma_map_ops *ops)
 {
+	if (use_dma_iommu(dev))
+		return false;
+
 	if (likely(!ops))
 		return true;
+
 #ifdef CONFIG_DMA_OPS_BYPASS
 	if (dev->dma_ops_bypass)
 		return min_not_zero(mask, dev->bus_dma_limit) >=
@@ -159,6 +176,8 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page,
 	if (dma_map_direct(dev, ops) ||
 	    arch_dma_map_page_direct(dev, page_to_phys(page) + offset + size))
 		addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);
+	else if (use_dma_iommu(dev))
+		addr = iommu_dma_map_page(dev, page, offset, size, dir, attrs);
 	else
 		addr = ops->map_page(dev, page, offset, size, dir, attrs);
 	kmsan_handle_dma(page, offset, size, dir);
@@ -177,6 +196,8 @@ void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size,
 	if (dma_map_direct(dev, ops) ||
 	    arch_dma_unmap_page_direct(dev, addr + size))
 		dma_direct_unmap_page(dev, addr, size, dir, attrs);
+	else if (use_dma_iommu(dev))
+		iommu_dma_unmap_page(dev, addr, size, dir, attrs);
 	else
 		ops->unmap_page(dev, addr, size, dir, attrs);
 	debug_dma_unmap_page(dev, addr, size, dir);
@@ -197,6 +218,8 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
 	if (dma_map_direct(dev, ops) ||
 	    arch_dma_map_sg_direct(dev, sg, nents))
 		ents = dma_direct_map_sg(dev, sg, nents, dir, attrs);
+	else if (use_dma_iommu(dev))
+		ents = iommu_dma_map_sg(dev, sg, nents, dir, attrs);
 	else
 		ents = ops->map_sg(dev, sg, nents, dir, attrs);
 
@@ -291,7 +314,9 @@ void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
 	if (dma_map_direct(dev, ops) ||
 	    arch_dma_unmap_sg_direct(dev, sg, nents))
 		dma_direct_unmap_sg(dev, sg, nents, dir, attrs);
-	else
+	else if (use_dma_iommu(dev))
+		iommu_dma_unmap_sg(dev, sg, nents, dir, attrs);
+	else if (ops->unmap_sg)
 		ops->unmap_sg(dev, sg, nents, dir, attrs);
 }
 EXPORT_SYMBOL(dma_unmap_sg_attrs);
@@ -309,6 +334,8 @@ dma_addr_t dma_map_resource(struct device *dev, phys_addr_t phys_addr,
 
 	if (dma_map_direct(dev, ops))
 		addr = dma_direct_map_resource(dev, phys_addr, size, dir, attrs);
+	else if (use_dma_iommu(dev))
+		addr = iommu_dma_map_resource(dev, phys_addr, size, dir, attrs);
 	else if (ops->map_resource)
 		addr = ops->map_resource(dev, phys_addr, size, dir, attrs);
 
@@ -323,7 +350,11 @@ void dma_unmap_resource(struct device *dev, dma_addr_t addr, size_t size,
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
 	BUG_ON(!valid_dma_direction(dir));
-	if (!dma_map_direct(dev, ops) && ops->unmap_resource)
+	if (dma_map_direct(dev, ops))
+		; /* nothing to do: uncached and no swiotlb */
+	else if (use_dma_iommu(dev))
+		iommu_dma_unmap_resource(dev, addr, size, dir, attrs);
+	else if (ops->unmap_resource)
 		ops->unmap_resource(dev, addr, size, dir, attrs);
 	debug_dma_unmap_resource(dev, addr, size, dir);
 }
@@ -338,6 +369,8 @@ void __dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, size_t size,
 	BUG_ON(!valid_dma_direction(dir));
 	if (dma_map_direct(dev, ops))
 		dma_direct_sync_single_for_cpu(dev, addr, size, dir);
+	else if (use_dma_iommu(dev))
+		iommu_dma_sync_single_for_cpu(dev, addr, size, dir);
 	else if (ops->sync_single_for_cpu)
 		ops->sync_single_for_cpu(dev, addr, size, dir);
 	debug_dma_sync_single_for_cpu(dev, addr, size, dir);
@@ -352,6 +385,8 @@ void __dma_sync_single_for_device(struct device *dev, dma_addr_t addr,
 	BUG_ON(!valid_dma_direction(dir));
 	if (dma_map_direct(dev, ops))
 		dma_direct_sync_single_for_device(dev, addr, size, dir);
+	else if (use_dma_iommu(dev))
+		iommu_dma_sync_single_for_device(dev, addr, size, dir);
 	else if (ops->sync_single_for_device)
 		ops->sync_single_for_device(dev, addr, size, dir);
 	debug_dma_sync_single_for_device(dev, addr, size, dir);
@@ -366,6 +401,8 @@ void __dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 	BUG_ON(!valid_dma_direction(dir));
 	if (dma_map_direct(dev, ops))
 		dma_direct_sync_sg_for_cpu(dev, sg, nelems, dir);
+	else if (use_dma_iommu(dev))
+		iommu_dma_sync_sg_for_cpu(dev, sg, nelems, dir);
 	else if (ops->sync_sg_for_cpu)
 		ops->sync_sg_for_cpu(dev, sg, nelems, dir);
 	debug_dma_sync_sg_for_cpu(dev, sg, nelems, dir);
@@ -380,6 +417,8 @@ void __dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 	BUG_ON(!valid_dma_direction(dir));
 	if (dma_map_direct(dev, ops))
 		dma_direct_sync_sg_for_device(dev, sg, nelems, dir);
+	else if (use_dma_iommu(dev))
+		iommu_dma_sync_sg_for_device(dev, sg, nelems, dir);
 	else if (ops->sync_sg_for_device)
 		ops->sync_sg_for_device(dev, sg, nelems, dir);
 	debug_dma_sync_sg_for_device(dev, sg, nelems, dir);
@@ -405,7 +444,7 @@ static void dma_setup_need_sync(struct device *dev)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
-	if (dma_map_direct(dev, ops) || (ops->flags & DMA_F_CAN_SKIP_SYNC))
+	if (dma_map_direct(dev, ops) || use_dma_iommu(dev))
 		/*
 		 * dma_skip_sync will be reset to %false on first SWIOTLB buffer
 		 * mapping, if any. During the device initialization, it's
@@ -446,6 +485,9 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
 	if (dma_alloc_direct(dev, ops))
 		return dma_direct_get_sgtable(dev, sgt, cpu_addr, dma_addr,
 				size, attrs);
+	if (use_dma_iommu(dev))
+		return iommu_dma_get_sgtable(dev, sgt, cpu_addr, dma_addr,
+				size, attrs);
 	if (!ops->get_sgtable)
 		return -ENXIO;
 	return ops->get_sgtable(dev, sgt, cpu_addr, dma_addr, size, attrs);
@@ -482,6 +524,8 @@ bool dma_can_mmap(struct device *dev)
 
 	if (dma_alloc_direct(dev, ops))
 		return dma_direct_can_mmap(dev);
+	if (use_dma_iommu(dev))
+		return true;
 	return ops->mmap != NULL;
 }
 EXPORT_SYMBOL_GPL(dma_can_mmap);
@@ -508,6 +552,9 @@ int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 	if (dma_alloc_direct(dev, ops))
 		return dma_direct_mmap(dev, vma, cpu_addr, dma_addr, size,
 				attrs);
+	if (use_dma_iommu(dev))
+		return iommu_dma_mmap(dev, vma, cpu_addr, dma_addr, size,
+				      attrs);
 	if (!ops->mmap)
 		return -ENXIO;
 	return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
@@ -559,6 +606,8 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
 
 	if (dma_alloc_direct(dev, ops))
 		cpu_addr = dma_direct_alloc(dev, size, dma_handle, flag, attrs);
+	else if (use_dma_iommu(dev))
+		cpu_addr = iommu_dma_alloc(dev, size, dma_handle, flag, attrs);
 	else if (ops->alloc)
 		cpu_addr = ops->alloc(dev, size, dma_handle, flag, attrs);
 	else
@@ -591,6 +640,8 @@ void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
 	debug_dma_free_coherent(dev, size, cpu_addr, dma_handle);
 	if (dma_alloc_direct(dev, ops))
 		dma_direct_free(dev, size, cpu_addr, dma_handle, attrs);
+	else if (use_dma_iommu(dev))
+		iommu_dma_free(dev, size, cpu_addr, dma_handle, attrs);
 	else if (ops->free)
 		ops->free(dev, size, cpu_addr, dma_handle, attrs);
 }
@@ -611,6 +662,8 @@ static struct page *__dma_alloc_pages(struct device *dev, size_t size,
 	size = PAGE_ALIGN(size);
 	if (dma_alloc_direct(dev, ops))
 		return dma_direct_alloc_pages(dev, size, dma_handle, dir, gfp);
+	if (use_dma_iommu(dev))
+		return dma_common_alloc_pages(dev, size, dma_handle, dir, gfp);
 	if (!ops->alloc_pages_op)
 		return NULL;
 	return ops->alloc_pages_op(dev, size, dma_handle, dir, gfp);
@@ -635,6 +688,8 @@ static void __dma_free_pages(struct device *dev, size_t size, struct page *page,
 	size = PAGE_ALIGN(size);
 	if (dma_alloc_direct(dev, ops))
 		dma_direct_free_pages(dev, size, page, dma_handle, dir);
+	else if (use_dma_iommu(dev))
+		dma_common_free_pages(dev, size, page, dma_handle, dir);
 	else if (ops->free_pages)
 		ops->free_pages(dev, size, page, dma_handle, dir);
 }
@@ -697,6 +752,8 @@ struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
 
 	if (ops && ops->alloc_noncontiguous)
 		sgt = ops->alloc_noncontiguous(dev, size, dir, gfp, attrs);
+	else if (use_dma_iommu(dev))
+		sgt = iommu_dma_alloc_noncontiguous(dev, size, dir, gfp, attrs);
 	else
 		sgt = alloc_single_sgt(dev, size, dir, gfp);
 
@@ -725,6 +782,8 @@ void dma_free_noncontiguous(struct device *dev, size_t size,
 	debug_dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
 	if (ops && ops->free_noncontiguous)
 		ops->free_noncontiguous(dev, size, sgt, dir);
+	else if (use_dma_iommu(dev))
+		iommu_dma_free_noncontiguous(dev, size, sgt, dir);
 	else
 		free_single_sgt(dev, size, sgt, dir);
 }
@@ -772,6 +831,8 @@ static int dma_supported(struct device *dev, u64 mask)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
+	if (WARN_ON(ops && use_dma_iommu(dev)))
+		return false;
 	/*
 	 * ->dma_supported sets the bypass flag, so we must always call
 	 * into the method here unless the device is truly direct mapped.
@@ -787,17 +848,14 @@ bool dma_pci_p2pdma_supported(struct device *dev)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
-	/* if ops is not set, dma direct will be used which supports P2PDMA */
-	if (!ops)
-		return true;
-
 	/*
 	 * Note: dma_ops_bypass is not checked here because P2PDMA should
 	 * not be used with dma mapping ops that do not have support even
 	 * if the specific device is bypassing them.
 	 */
 
-	return ops->flags & DMA_F_PCI_P2PDMA_SUPPORTED;
+	/* if ops is not set, dma direct and default IOMMU support P2PDMA */
+	return !ops;
 }
 EXPORT_SYMBOL_GPL(dma_pci_p2pdma_supported);
 
@@ -865,6 +923,8 @@ size_t dma_max_mapping_size(struct device *dev)
 
 	if (dma_map_direct(dev, ops))
 		size = dma_direct_max_mapping_size(dev);
+	else if (use_dma_iommu(dev))
+		size = iommu_dma_max_mapping_size(dev);
 	else if (ops && ops->max_mapping_size)
 		size = ops->max_mapping_size(dev);
 
@@ -877,9 +937,10 @@ size_t dma_opt_mapping_size(struct device *dev)
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 	size_t size = SIZE_MAX;
 
-	if (ops && ops->opt_mapping_size)
+	if (use_dma_iommu(dev))
+		size = iommu_dma_opt_mapping_size();
+	else if (ops && ops->opt_mapping_size)
 		size = ops->opt_mapping_size();
-
 	return min(dma_max_mapping_size(dev), size);
 }
 EXPORT_SYMBOL_GPL(dma_opt_mapping_size);
@@ -888,6 +949,9 @@ unsigned long dma_get_merge_boundary(struct device *dev)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
+	if (use_dma_iommu(dev))
+		return iommu_dma_get_merge_boundary(dev);
+
 	if (!ops || !ops->get_merge_boundary)
 		return 0;	/* can't merge */
 
-- 
2.45.2

Re: [PATCH v3 2/2] dma: add IOMMU static calls with clear default ops

[Christoph Hellwig]

On Sun, Jul 21, 2024 at 10:49:11AM +0300, Leon Romanovsky wrote:
> -static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
> -		struct sg_table *sgt, enum dma_data_direction dir)
> +void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
> +				  struct sg_table *sgt,
> +				  enum dma_data_direction dir)

Why are you reformatting these to a much less readable coding style?

> +static inline struct page *
> +dma_common_alloc_pages(struct device *dev, size_t size, dma_addr_t *dma_handle,
> +		       enum dma_data_direction dir, gfp_t gfp)
> +{
> +	return NULL;
> +}
> +static inline void dma_common_free_pages(struct device *dev, size_t size,
> +					 struct page *vaddr,
> +					 dma_addr_t dma_handle,
> +					 enum dma_data_direction dir)
> +{
> +}

dma-iommu very much depends on these.  So we'll need to also
build ops_helpers.o if dma-iommu is enabled.  So we'll probably need
a separate Kconfig option for it that the various users select.

Re: [PATCH v3 2/2] dma: add IOMMU static calls with clear default ops

[Leon Romanovsky]

On Mon, Jul 22, 2024 at 05:10:37PM +0200, Christoph Hellwig wrote:
> On Sun, Jul 21, 2024 at 10:49:11AM +0300, Leon Romanovsky wrote:
> > -static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
> > -		struct sg_table *sgt, enum dma_data_direction dir)
> > +void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
> > +				  struct sg_table *sgt,
> > +				  enum dma_data_direction dir)
> 
> Why are you reformatting these to a much less readable coding style?

I'm relying on clang-formatter to format the code, see .clang-format
file in the kernel root directory.

> 
> > +static inline struct page *
> > +dma_common_alloc_pages(struct device *dev, size_t size, dma_addr_t *dma_handle,
> > +		       enum dma_data_direction dir, gfp_t gfp)
> > +{
> > +	return NULL;
> > +}
> > +static inline void dma_common_free_pages(struct device *dev, size_t size,
> > +					 struct page *vaddr,
> > +					 dma_addr_t dma_handle,
> > +					 enum dma_data_direction dir)
> > +{
> > +}
> 
> dma-iommu very much depends on these.  So we'll need to also
> build ops_helpers.o if dma-iommu is enabled.  So we'll probably need
> a separate Kconfig option for it that the various users select.
> 

I removed them from dma-iommu.c and there are no calls to them in that file.
➜  kernel git:(m/dma-v2) git grep dma_common_alloc_pages drivers/iommu/ | wc -l
0

Thanks

Re: [PATCH v3 2/2] dma: add IOMMU static calls with clear default ops

[Christoph Hellwig]

On Mon, Jul 22, 2024 at 06:44:58PM +0300, Leon Romanovsky wrote:
> On Mon, Jul 22, 2024 at 05:10:37PM +0200, Christoph Hellwig wrote:
> > On Sun, Jul 21, 2024 at 10:49:11AM +0300, Leon Romanovsky wrote:
> > > -static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
> > > -		struct sg_table *sgt, enum dma_data_direction dir)
> > > +void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
> > > +				  struct sg_table *sgt,
> > > +				  enum dma_data_direction dir)
> > 
> > Why are you reformatting these to a much less readable coding style?
> 
> I'm relying on clang-formatter to format the code, see .clang-format
> file in the kernel root directory.

Well, that uses a really horrible default then.  Aligning to the opening
brace not only is hard to read, but requireѕ reformatting with every
addition and removal of a static like here, or when trivially changing
the function name.

> > > +static inline void dma_common_free_pages(struct device *dev, size_t size,
> > > +					 struct page *vaddr,
> > > +					 dma_addr_t dma_handle,
> > > +					 enum dma_data_direction dir)
> > > +{
> > > +}
> > 
> > dma-iommu very much depends on these.  So we'll need to also
> > build ops_helpers.o if dma-iommu is enabled.  So we'll probably need
> > a separate Kconfig option for it that the various users select.
> > 
> 
> I removed them from dma-iommu.c and there are no calls to them in that file.
> ➜  kernel git:(m/dma-v2) git grep dma_common_alloc_pages drivers/iommu/ | wc -l

Well, you replaced them with direct calls from mapping.c, which now
needs them if dma-iommu is supported.  So while strictly speaking
dma-iommu doesn't need them, proper operation with dma-iommu still
needs them.

Re: [PATCH v3 2/2] dma: add IOMMU static calls with clear default ops

[Leon Romanovsky]

On Mon, Jul 22, 2024 at 05:49:29PM +0200, Christoph Hellwig wrote:
> On Mon, Jul 22, 2024 at 06:44:58PM +0300, Leon Romanovsky wrote:
> > On Mon, Jul 22, 2024 at 05:10:37PM +0200, Christoph Hellwig wrote:
> > > On Sun, Jul 21, 2024 at 10:49:11AM +0300, Leon Romanovsky wrote:
> > > > -static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
> > > > -		struct sg_table *sgt, enum dma_data_direction dir)
> > > > +void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
> > > > +				  struct sg_table *sgt,
> > > > +				  enum dma_data_direction dir)
> > > 
> > > Why are you reformatting these to a much less readable coding style?
> > 
> > I'm relying on clang-formatter to format the code, see .clang-format
> > file in the kernel root directory.
> 
> Well, that uses a really horrible default then.  Aligning to the opening
> brace not only is hard to read, but requireѕ reformatting with every
> addition and removal of a static like here, or when trivially changing
> the function name.

Should I need to reformat the code to your preferred style?
I can do it, but it will be manual work :(.

> 
> > > > +static inline void dma_common_free_pages(struct device *dev, size_t size,
> > > > +					 struct page *vaddr,
> > > > +					 dma_addr_t dma_handle,
> > > > +					 enum dma_data_direction dir)
> > > > +{
> > > > +}
> > > 
> > > dma-iommu very much depends on these.  So we'll need to also
> > > build ops_helpers.o if dma-iommu is enabled.  So we'll probably need
> > > a separate Kconfig option for it that the various users select.
> > > 
> > 
> > I removed them from dma-iommu.c and there are no calls to them in that file.
> > ➜  kernel git:(m/dma-v2) git grep dma_common_alloc_pages drivers/iommu/ | wc -l
> 
> Well, you replaced them with direct calls from mapping.c, which now
> needs them if dma-iommu is supported.  So while strictly speaking
> dma-iommu doesn't need them, proper operation with dma-iommu still
> needs them.

No problem, I can add.

Thanks

> 

Re: [PATCH v3 2/2] dma: add IOMMU static calls with clear default ops

[Christoph Hellwig]

On Mon, Jul 22, 2024 at 07:05:55PM +0300, Leon Romanovsky wrote:
> Should I need to reformat the code to your preferred style?
> I can do it, but it will be manual work :(.

Just keep it as it was. And preferably also follow the style in
dma-iommu.h.  In the worst case I can just fix it up when applying
the patch.