Re: [RFC PATCH v2 04/11] PCI/P2PDMA: Introduce pci_p2pdma_should_map_bus() and pci_p2pdma_bus_offset()
From: Christoph Hellwig <hch@lst.de>
Date: 2021-03-16 08:15:13
Also in:
linux-iommu, linux-mm, linux-nvme, linux-pci, lkml
On Thu, Mar 11, 2021 at 04:31:34PM -0700, Logan Gunthorpe wrote:
quoted hunk ↗ jump to hunk
Introduce pci_p2pdma_should_map_bus() which is meant to be called by DMA map functions to determine how to map a given p2pdma page. pci_p2pdma_bus_offset() is also added to allow callers to get the bus offset if they need to map the bus address. Signed-off-by: Logan Gunthorpe <logang@deltatee.com> --- drivers/pci/p2pdma.c | 50 ++++++++++++++++++++++++++++++++++++++ include/linux/pci-p2pdma.h | 11 +++++++++ 2 files changed, 61 insertions(+)diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 7f6836732bce..66d16b7eb668 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c@@ -912,6 +912,56 @@ void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, } EXPORT_SYMBOL_GPL(pci_p2pdma_unmap_sg_attrs); +/** + * pci_p2pdma_bus_offset - returns the bus offset for a given page + * @page: page to get the offset for + * + * Must be passed a PCI p2pdma page. + */ +u64 pci_p2pdma_bus_offset(struct page *page) +{ + struct pci_p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(page->pgmap); + + WARN_ON(!is_pci_p2pdma_page(page)); + + return p2p_pgmap->bus_offset; +} +EXPORT_SYMBOL_GPL(pci_p2pdma_bus_offset);
I don't see why this would be exported.
+EXPORT_SYMBOL_GPL(pci_p2pdma_dma_map_type);
Same here. Also the two helpers don't really look very related. I suspect you really want to move the p2p handling bits currenly added to kernel/dma/direct.c into drivers/pci/p2pdma.c instead, as that will allow direct access to the pci_p2pdma_pagemap and should thus simplify things quite a bit.