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From:   Logan Gunthorpe <logang@deltatee.com>
To:     linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-block@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-mm@kvack.org, iommu@lists.linux-foundation.org
Cc:     Stephen Bates <sbates@raithlin.com>,
        Christoph Hellwig <hch@lst.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Don Dutile <ddutile@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Jakowski Andrzej <andrzej.jakowski@intel.com>,
        Minturn Dave B <dave.b.minturn@intel.com>,
        Jason Ekstrand <jason@jlekstrand.net>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Xiong Jianxin <jianxin.xiong@intel.com>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Ira Weiny <ira.weiny@intel.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Logan Gunthorpe <logang@deltatee.com>
Date:   Thu,  8 Apr 2021 11:01:14 -0600
Message-Id: <20210408170123.8788-8-logang@deltatee.com>
In-Reply-To: <20210408170123.8788-1-logang@deltatee.com>
References: <20210408170123.8788-1-logang@deltatee.com>
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Subject: [PATCH 07/16] PCI/P2PDMA: Make pci_p2pdma_map_type() non-static
Precedence: bulk

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)
-- 
2.20.1