From 159bf19270e80b5bc4b13aa88072dcb390b4d297 Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Fri, 8 Jul 2022 10:50:57 -0600 Subject: [PATCH] dma-mapping: add flags to dma_map_ops to indicate PCI P2PDMA support Add a flags member to the dma_map_ops structure with one flag to indicate support for PCI P2PDMA. Also, add a helper to check if a device supports PCI P2PDMA. Signed-off-by: Logan Gunthorpe Reviewed-by: Jason Gunthorpe Reviewed-by: Christoph Hellwig Signed-off-by: Christoph Hellwig --- include/linux/dma-map-ops.h | 10 ++++++++++ include/linux/dma-mapping.h | 5 +++++ kernel/dma/mapping.c | 18 ++++++++++++++++++ 3 files changed, 33 insertions(+) diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h index 99cec59..010df04 100644 --- a/include/linux/dma-map-ops.h +++ b/include/linux/dma-map-ops.h @@ -11,7 +11,17 @@ struct cma; +/* + * Values for struct dma_map_ops.flags: + * + * DMA_F_PCI_P2PDMA_SUPPORTED: Indicates the dma_map_ops implementation can + * handle PCI P2PDMA pages in the map_sg/unmap_sg operation. + */ +#define DMA_F_PCI_P2PDMA_SUPPORTED (1 << 0) + struct dma_map_ops { + unsigned int flags; + void *(*alloc)(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs); diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index fe38494..25a3090 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -140,6 +140,7 @@ int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma, unsigned long attrs); bool dma_can_mmap(struct device *dev); int dma_supported(struct device *dev, u64 mask); +bool dma_pci_p2pdma_supported(struct device *dev); int dma_set_mask(struct device *dev, u64 mask); int dma_set_coherent_mask(struct device *dev, u64 mask); u64 dma_get_required_mask(struct device *dev); @@ -251,6 +252,10 @@ static inline int dma_supported(struct device *dev, u64 mask) { return 0; } +static inline bool dma_pci_p2pdma_supported(struct device *dev) +{ + return false; +} static inline int dma_set_mask(struct device *dev, u64 mask) { return -EIO; diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 746d468..a9ce5d7 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -723,6 +723,24 @@ int dma_supported(struct device *dev, u64 mask) } EXPORT_SYMBOL(dma_supported); +bool dma_pci_p2pdma_supported(struct device *dev) +{ + const struct dma_map_ops *ops = get_dma_ops(dev); + + /* if ops is not set, dma direct will be used which supports P2PDMA */ + if (!ops) + return true; + + /* + * Note: dma_ops_bypass is not checked here because P2PDMA should + * not be used with dma mapping ops that do not have support even + * if the specific device is bypassing them. + */ + + return ops->flags & DMA_F_PCI_P2PDMA_SUPPORTED; +} +EXPORT_SYMBOL_GPL(dma_pci_p2pdma_supported); + #ifdef CONFIG_ARCH_HAS_DMA_SET_MASK void arch_dma_set_mask(struct device *dev, u64 mask); #else -- 2.7.4