Re: [PATCH 07/16] PCI/P2PDMA: Make pci_p2pdma_map_type() non-static

Don Dutile
2021-05-11T16:06:26Z

On 4/8/21 1:01 PM, Logan Gunthorpe wrote:
> pci_p2pdma_map_type() will be needed by the dma-iommu map_sg
> implementation because it will need to determine the mapping type
> ahead of actually doing the mapping to create the actual iommu mapping.
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> ---
> drivers/pci/p2pdma.c | 34 +++++++++++++++++++++++-----------
> include/linux/pci-p2pdma.h | 15 +++++++++++++++
> 2 files changed, 38 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index bcb1a6d6119d..38c93f57a941 100644
> --- a/drivers/pci/p2pdma.c
> +++ b/drivers/pci/p2pdma.c
> @@ -20,13 +20,6 @@
> #include <linux/seq_buf.h>
> #include <linux/xarray.h>
>
> -enum pci_p2pdma_map_type {
> - PCI_P2PDMA_MAP_UNKNOWN = 0,
> - PCI_P2PDMA_MAP_NOT_SUPPORTED,
> - PCI_P2PDMA_MAP_BUS_ADDR,
> - PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
> -};
> -
> struct pci_p2pdma {
> struct gen_pool *pool;
> bool p2pmem_published;
> @@ -822,13 +815,30 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
> }
> EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
>
> -static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
> - struct device *dev)
> +/**
> + * pci_p2pdma_map_type - return the type of mapping that should be used for
> + * a given device and pgmap
> + * @pgmap: the pagemap of a page to determine the mapping type for
> + * @dev: device that is mapping the page
> + * @dma_attrs: the attributes passed to the dma_map operation --
> + * this is so they can be checked to ensure P2PDMA pages were not
> + * introduced into an incorrect interface (like dma_map_sg). *
> + *
> + * Returns one of:
> + * PCI_P2PDMA_MAP_NOT_SUPPORTED - The mapping should not be done
> + * PCI_P2PDMA_MAP_BUS_ADDR - The mapping should use the PCI bus address
> + * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE - The mapping should be done directly
> + */
I'd recommend putting these descriptions in the enum's in pci-p2pdma.h .
Also, can you use a better description for THRU_HOST_BRIDGE -- it leaves the reader wondering what 'done directly' means.

Thanks.
-dd

> +enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
> + struct device *dev, unsigned long dma_attrs)
> {
> struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider;
> enum pci_p2pdma_map_type ret;
> struct pci_dev *client;
>
> + WARN_ONCE(!(dma_attrs & __DMA_ATTR_PCI_P2PDMA),
> + "PCI P2PDMA pages were mapped with dma_map_sg!");
> +
> if (!provider->p2pdma)
> return PCI_P2PDMA_MAP_NOT_SUPPORTED;
>
> @@ -879,7 +889,8 @@ int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
> struct pci_p2pdma_pagemap *p2p_pgmap =
> to_p2p_pgmap(sg_page(sg)->pgmap);
>
> - switch (pci_p2pdma_map_type(sg_page(sg)->pgmap, dev)) {
> + switch (pci_p2pdma_map_type(sg_page(sg)->pgmap, dev,
> + __DMA_ATTR_PCI_P2PDMA)) {
> case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> return dma_map_sg_attrs(dev, sg, nents, dir, attrs);
> case PCI_P2PDMA_MAP_BUS_ADDR:
> @@ -904,7 +915,8 @@ void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
> {
> enum pci_p2pdma_map_type map_type;
>
> - map_type = pci_p2pdma_map_type(sg_page(sg)->pgmap, dev);
> + map_type = pci_p2pdma_map_type(sg_page(sg)->pgmap, dev,
> + __DMA_ATTR_PCI_P2PDMA);
>
> if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE)
> dma_unmap_sg_attrs(dev, sg, nents, dir, attrs);
> diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
> index 8318a97c9c61..a06072ac3a52 100644
> --- a/include/linux/pci-p2pdma.h
> +++ b/include/linux/pci-p2pdma.h
> @@ -16,6 +16,13 @@
> struct block_device;
> struct scatterlist;
>
> +enum pci_p2pdma_map_type {
> + PCI_P2PDMA_MAP_UNKNOWN = 0,
> + PCI_P2PDMA_MAP_NOT_SUPPORTED,
> + PCI_P2PDMA_MAP_BUS_ADDR,
> + PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
> +};
> +
> #ifdef CONFIG_PCI_P2PDMA
> int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
> u64 offset);
> @@ -30,6 +37,8 @@ struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
> unsigned int *nents, u32 length);
> void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl);
> void pci_p2pmem_publish(struct pci_dev *pdev, bool publish);
> +enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
> + struct device *dev, unsigned long dma_attrs);
> int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
> int nents, enum dma_data_direction dir, unsigned long attrs);
> void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
> @@ -83,6 +92,12 @@ 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 enum pci_p2pdma_map_type pci_p2pdma_map_type(
> + struct dev_pagemap *pgmap, struct device *dev,
> + unsigned long dma_attrs)
> +{
> + return PCI_P2PDMA_MAP_NOT_SUPPORTED;
> +}
> static inline int pci_p2pdma_map_sg_attrs(struct device *dev,
> struct scatterlist *sg, int nents, enum dma_data_direction dir,
> unsigned long attrs)