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dma-mapping: add flags to dma_map_ops to indicate PCI P2PDMA support

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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 <logang@deltatee.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Logan Gunthorpe 2022-07-08 10:50:57 -06:00 committed by Christoph Hellwig
parent f02ad36d4f
commit 159bf19270
3 changed files with 33 additions and 0 deletions
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10
include/linux/dma-map-ops.h
View file

@ -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);

5
include/linux/dma-mapping.h
View file

@ -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;

18
kernel/dma/mapping.c
View file

@ -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