On Thu, Sep 16, 2021 at 05:40:43PM -0600, 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.
I don't expect this to go via the PCI tree, but if it did I would
silently:
s/PCI/P2PDMA: make pci_p2pdma_map_type() non-static/
PCI/P2PDMA: Expose pci_p2pdma_map_type()/
s/iommu/IOMMU/
and mention what this patch does in the commit log (in addition to the
subject) and fix a couple minor typos below.
> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> drivers/pci/p2pdma.c | 24 +++++++++++++---------
> include/linux/pci-p2pdma.h | 41 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 56 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index 1192c465ba6d..b656d8c801a7 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;
> @@ -841,8 +834,21 @@ 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
> + *
> + * 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 normally
> + * using the CPU physical address (in dma-direct) or an IOVA
> + * mapping for the IOMMU.
> + */
> +enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
> + struct device *dev)
> {
> enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
> struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider;
> diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
> index 8318a97c9c61..caac2d023f8f 100644
> --- a/include/linux/pci-p2pdma.h
> +++ b/include/linux/pci-p2pdma.h
> @@ -16,6 +16,40 @@
> struct block_device;
> struct scatterlist;
>
> +enum pci_p2pdma_map_type {
> + /*
> + * PCI_P2PDMA_MAP_UNKNOWN: Used internally for indicating the mapping
> + * type hasn't been calculated yet. Functions that return this enum
> + * never return this value.
> + */
> + PCI_P2PDMA_MAP_UNKNOWN = 0,
> +
> + /*
> + * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will
> + * traverse the host bridge and the host bridge is not in the
> + * whitelist. DMA Mapping routines should return an error when
> + * this is returned.
> + */
> + PCI_P2PDMA_MAP_NOT_SUPPORTED,
> +
> + /*
> + * PCI_P2PDMA_BUS_ADDR: Indicates that two devices can talk to
> + * eachother directly through a PCI switch and the transaction will
> + * not traverse the host bridge. Such a mapping should program
> + * the DMA engine with PCI bus addresses.
s/eachother/each other/
> + */
> + PCI_P2PDMA_MAP_BUS_ADDR,
> +
> + /*
> + * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: Indicates two devices can talk
> + * to eachother, but the transaction traverses a host bridge on the
> + * whitelist. In this case, a normal mapping either with CPU physical
> + * addresses (in the case of dma-direct) or IOVA addresses (in the
> + * case of IOMMUs) should be used to program the DMA engine.
s/eachother/each other/
> + */
> + 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 +64,8 @@ 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);
> 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 +119,11 @@ 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)
> +{
> + 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)
> --
> 2.30.2
>
