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

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Message-Id: <20180104190137.7654-4-logang@deltatee.com>
Date:   Thu,  4 Jan 2018 12:01:28 -0700
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-rdma@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-block@...r.kernel.org
Cc:     Stephen Bates <sbates@...thlin.com>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Keith Busch <keith.busch@...el.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Max Gurtovoy <maxg@...lanox.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH 03/12] pci-p2p: Add PCI p2pmem dma mappings to adjust the bus offset

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@...tatee.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