[PATCH 03/12] pci-p2p: Add PCI p2pmem dma mappings to adjust the bus offset

Logan Gunthorpe
2018-01-04T19:02:03Z

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 <logang@deltatee.com>
---
drivers/pci/p2p.c | 43 +++++++++++++++++++++++++++++++++++++++++++
include/linux/memremap.h | 1 +
include/linux/pci-p2p.h | 9 +++++++++
3 files changed, 53 insertions(+)

diff --git a/drivers/pci/p2p.c b/drivers/pci/p2p.c
index 03330c7b5e6d..87cec87b02e3 100644
--- a/drivers/pci/p2p.c
+++ b/drivers/pci/p2p.c
@@ -184,6 +184,8 @@ int pci_p2pmem_add_resource(struct pci_dev *pdev, int bar, size_t size,
pgmap->res.end = pgmap->res.start + size - 1;
pgmap->ref = &pdev->p2p->devmap_ref;
pgmap->type = MEMORY_DEVICE_PCI_P2P;
+ pgmap->pci_p2p_bus_offset = pci_bus_address(pdev, bar) -
+ pci_resource_start(pdev, bar);

addr = devm_memremap_pages(&pdev->dev, pgmap);
if (IS_ERR(addr))
@@ -598,3 +600,44 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
pdev->p2p->published = publish;
}
EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
+
+/*
+ * pci_p2pmem_map_sg - map a pci p2p sg for dma
+ * @sg:scatter list to map
+ * @nents:elements in the scatter list
+ *
+ * Returns the number of sgls mapped
+ */
+int pci_p2pmem_map_sg(struct scatterlist *sg, int nents)
+{
+ struct dev_pagemap *pgmap;
+ struct scatterlist *s;
+ phys_addr_t paddr;
+ int i;
+
+ for_each_sg(sg, s, nents, i) {
+ pgmap = sg_page(s)->pgmap;
+ paddr = sg_phys(s);
+
+ s->dma_address = paddr - pgmap->pci_p2p_bus_offset;
+ sg_dma_len(s) = s->length;
+ }
+
+ return nents;
+}
+EXPORT_SYMBOL_GPL(pci_p2pmem_map_sg);
+
+/**
+ * pci_p2pmem_unmap_sg - unmap a pci p2p sg for dma
+ * @sg:scatter list to map
+ * @nents:elements in the scatter list
+ */
+void pci_p2pmem_unmap_sg(struct scatterlist *sg, int nents)
+{
+ struct scatterlist *s;
+ int i;
+
+ for_each_sg(sg, s, nents, i)
+ dma_mark_clean(phys_to_virt(sg_phys(s)), sg_dma_len(s));
+}
+EXPORT_SYMBOL_GPL(pci_p2pmem_unmap_sg);
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index c17a6d167d48..a792f87b9dc3 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_p2p_bus_offset;
};

#ifdef CONFIG_ZONE_DEVICE
diff --git a/include/linux/pci-p2p.h b/include/linux/pci-p2p.h
index f811c97a5886..154c39905fc9 100644
--- a/include/linux/pci-p2p.h
+++ b/include/linux/pci-p2p.h
@@ -34,6 +34,8 @@ 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_p2pmem_map_sg(struct scatterlist *sg, int nents);
+void pci_p2pmem_unmap_sg(struct scatterlist *sg, int nents);
#else /* CONFIG_PCI_P2P */
static inline int pci_p2pmem_add_resource(struct pci_dev *pdev, int bar,
size_t size, u64 offset)
@@ -81,5 +83,12 @@ 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 int pci_p2pmem_map_sg(struct scatterlist *sg, int nents)
+{
+ return -ENODEV;
+}
+static inline void pci_p2pmem_unmap_sg(struct scatterlist *sg, int nents)
+{
+}
#endif /* CONFIG_PCI_P2P */
#endif /* _LINUX_PCI_P2P_H */
--
2.11.0