The DMA address used when mapping PCI P2P memory must be the PCI bus
address. Thus, introduce pci_p2pmem_[un]map_sg() to map the correct
addresses when using P2P memory.

For this, we assume that an SGL passed to these functions contain all
P2P memory or no P2P memory.

Signed-off-by: Logan Gunthorpe <log...@deltatee.com>
---
 drivers/pci/p2pdma.c       | 51 ++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/memremap.h   |  1 +
 include/linux/pci-p2pdma.h | 13 ++++++++++++
 3 files changed, 65 insertions(+)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index fd4789566a56..ab810c3a93eb 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -190,6 +190,8 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, 
size_t size,
        pgmap->res.flags = pci_resource_flags(pdev, bar);
        pgmap->ref = &pdev->p2pdma->devmap_ref;
        pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
+       pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) -
+               pci_resource_start(pdev, bar);
 
        addr = devm_memremap_pages(&pdev->dev, pgmap);
        if (IS_ERR(addr)) {
@@ -731,3 +733,52 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
        pdev->p2pdma->p2pmem_published = publish;
 }
 EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
+
+/**
+ * pci_p2pdma_map_sg - map a PCI peer-to-peer sg for DMA
+ * @dev: device doing the DMA request
+ * @sg: scatter list to map
+ * @nents: elements in the scatterlist
+ * @dir: DMA direction
+ *
+ * Returns the number of SG entries mapped
+ */
+int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
+                     enum dma_data_direction dir)
+{
+       struct dev_pagemap *pgmap;
+       struct scatterlist *s;
+       phys_addr_t paddr;
+       int i;
+
+       /*
+        * p2pdma mappings are not compatible with devices that use
+        * dma_virt_ops.
+        */
+       if (IS_ENABLED(CONFIG_DMA_VIRT_OPS) && dev->dma_ops == &dma_virt_ops)
+               return 0;
+
+       for_each_sg(sg, s, nents, i) {
+               pgmap = sg_page(s)->pgmap;
+               paddr = sg_phys(s);
+
+               s->dma_address = paddr - pgmap->pci_p2pdma_bus_offset;
+               sg_dma_len(s) = s->length;
+       }
+
+       return nents;
+}
+EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg);
+
+/**
+ * pci_p2pdma_unmap_sg - unmap a PCI peer-to-peer sg for DMA
+ * @dev: device doing the DMA request
+ * @sg: scatter list to map
+ * @nents: elements in the scatterlist
+ * @dir: DMA direction
+ */
+void pci_p2pdma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
+                        enum dma_data_direction dir)
+{
+}
+EXPORT_SYMBOL_GPL(pci_p2pdma_unmap_sg);
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 9e907c338a44..1660f64ce96f 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -125,6 +125,7 @@ struct dev_pagemap {
        struct device *dev;
        void *data;
        enum memory_type type;
+       u64 pci_p2pdma_bus_offset;
 };
 
 #ifdef CONFIG_ZONE_DEVICE
diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
index 1f7856ff098b..59eb218bdb25 100644
--- a/include/linux/pci-p2pdma.h
+++ b/include/linux/pci-p2pdma.h
@@ -36,6 +36,10 @@ int pci_p2pmem_alloc_sgl(struct pci_dev *pdev, struct 
scatterlist **sgl,
 void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl,
                unsigned int nents);
 void pci_p2pmem_publish(struct pci_dev *pdev, bool publish);
+int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
+                     enum dma_data_direction dir);
+void pci_p2pdma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
+                        enum dma_data_direction dir);
 #else /* CONFIG_PCI_P2PDMA */
 static inline int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar,
                size_t size, u64 offset)
@@ -97,5 +101,14 @@ 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 int pci_p2pdma_map_sg(struct device *dev,
+       struct scatterlist *sg, int nents, enum dma_data_direction dir)
+{
+       return 0;
+}
+static inline void pci_p2pdma_unmap_sg(struct device *dev,
+       struct scatterlist *sg, int nents, enum dma_data_direction dir)
+{
+}
 #endif /* CONFIG_PCI_P2PDMA */
 #endif /* _LINUX_PCI_P2P_H */
-- 
2.11.0

_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

Reply via email to