pci_p2pdma_map_type() will be needed by the dma-iommu map_sg
implementation because it will need to determine the mapping type
ahead of actually doing the mapping to create the actual iommu mapping.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
  drivers/pci/p2pdma.c       | 34 +++++++++++++++++++++++-----------
  include/linux/pci-p2pdma.h | 15 +++++++++++++++
  2 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index bcb1a6d6119d..38c93f57a941 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c

@@ -20,13 +20,6 @@
  #include <linux/seq_buf.h>
  #include <linux/xarray.h>
  
-enum pci_p2pdma_map_type {
-	PCI_P2PDMA_MAP_UNKNOWN = 0,
-	PCI_P2PDMA_MAP_NOT_SUPPORTED,
-	PCI_P2PDMA_MAP_BUS_ADDR,
-	PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
-};
-
  struct pci_p2pdma {
  	struct gen_pool *pool;
  	bool p2pmem_published;

@@ -822,13 +815,30 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
  }
  EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
  
-static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
-						    struct device *dev)
+/**
+ * pci_p2pdma_map_type - return the type of mapping that should be used for
+ *	a given device and pgmap
+ * @pgmap: the pagemap of a page to determine the mapping type for
+ * @dev: device that is mapping the page
+ * @dma_attrs: the attributes passed to the dma_map operation --
+ *	this is so they can be checked to ensure P2PDMA pages were not
+ *	introduced into an incorrect interface (like dma_map_sg). *
+ *
+ * Returns one of:
+ *	PCI_P2PDMA_MAP_NOT_SUPPORTED - The mapping should not be done
+ *	PCI_P2PDMA_MAP_BUS_ADDR - The mapping should use the PCI bus address
+ *	PCI_P2PDMA_MAP_THRU_HOST_BRIDGE - The mapping should be done directly
+ */

+enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
+		struct device *dev, unsigned long dma_attrs)
  {
  	struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider;
  	enum pci_p2pdma_map_type ret;
  	struct pci_dev *client;
  
+	WARN_ONCE(!(dma_attrs & __DMA_ATTR_PCI_P2PDMA),
+		  "PCI P2PDMA pages were mapped with dma_map_sg!");
+
  	if (!provider->p2pdma)
  		return PCI_P2PDMA_MAP_NOT_SUPPORTED;
  

@@ -879,7 +889,8 @@ int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
  	struct pci_p2pdma_pagemap *p2p_pgmap =
  		to_p2p_pgmap(sg_page(sg)->pgmap);
  
-	switch (pci_p2pdma_map_type(sg_page(sg)->pgmap, dev)) {
+	switch (pci_p2pdma_map_type(sg_page(sg)->pgmap, dev,
+				    __DMA_ATTR_PCI_P2PDMA)) {
  	case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
  		return dma_map_sg_attrs(dev, sg, nents, dir, attrs);
  	case PCI_P2PDMA_MAP_BUS_ADDR:

@@ -904,7 +915,8 @@ void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
  {
  	enum pci_p2pdma_map_type map_type;
  
-	map_type = pci_p2pdma_map_type(sg_page(sg)->pgmap, dev);
+	map_type = pci_p2pdma_map_type(sg_page(sg)->pgmap, dev,
+				       __DMA_ATTR_PCI_P2PDMA);
  
  	if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE)
  		dma_unmap_sg_attrs(dev, sg, nents, dir, attrs);

diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
index 8318a97c9c61..a06072ac3a52 100644
--- a/include/linux/pci-p2pdma.h
+++ b/include/linux/pci-p2pdma.h

@@ -16,6 +16,13 @@
  struct block_device;
  struct scatterlist;
  
+enum pci_p2pdma_map_type {
+	PCI_P2PDMA_MAP_UNKNOWN = 0,
+	PCI_P2PDMA_MAP_NOT_SUPPORTED,
+	PCI_P2PDMA_MAP_BUS_ADDR,
+	PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
+};
+
  #ifdef CONFIG_PCI_P2PDMA
  int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
  		u64 offset);

@@ -30,6 +37,8 @@ struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
  					 unsigned int *nents, u32 length);
  void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl);
  void pci_p2pmem_publish(struct pci_dev *pdev, bool publish);
+enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
+		struct device *dev, unsigned long dma_attrs);
  int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
  		int nents, enum dma_data_direction dir, unsigned long attrs);
  void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,

@@ -83,6 +92,12 @@ static inline void pci_p2pmem_free_sgl(struct pci_dev *pdev,
  static inline void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
  {
  }
+static inline enum pci_p2pdma_map_type pci_p2pdma_map_type(
+		struct dev_pagemap *pgmap, struct device *dev,
+		unsigned long dma_attrs)
+{
+	return PCI_P2PDMA_MAP_NOT_SUPPORTED;
+}
  static inline int pci_p2pdma_map_sg_attrs(struct device *dev,
  		struct scatterlist *sg, int nents, enum dma_data_direction dir,
  		unsigned long attrs)