From patchwork Thu Apr 8 17:01:15 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Logan Gunthorpe X-Patchwork-Id: 12191963 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6483FC433B4 for ; Thu, 8 Apr 2021 17:02:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 08F35610CC for ; Thu, 8 Apr 2021 17:02:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 08F35610CC Authentication-Results: mail.kernel.org; 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identity=mailfrom; envelope-from=""; helo=ale.deltatee.com; client-ip=204.191.154.188 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617901300-151691 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Add pci_p2pdma_map_segment() as a helper for simple dma_map_sg() implementations. It takes an scatterlist segment that must point to a pci_p2pdma struct page and will map it if the mapping requires a bus address. The return value indicates whether the mapping required a bus address or whether the caller still needs to map the segment normally. If the segment should not be mapped, -EREMOTEIO is returned. This helper uses a state structure to track the changes to the pgmap across calls and avoid needing to lookup into the xarray for every page. Also add pci_p2pdma_map_bus_segment() which is useful for IOMMU dma_map_sg() implementations where the sg segment containing the page differs from the sg segment containing the DMA address. Signed-off-by: Logan Gunthorpe --- drivers/pci/p2pdma.c | 65 ++++++++++++++++++++++++++++++++++++++ include/linux/pci-p2pdma.h | 21 ++++++++++++ 2 files changed, 86 insertions(+) diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 38c93f57a941..44ad7664e875 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -923,6 +923,71 @@ void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, } EXPORT_SYMBOL_GPL(pci_p2pdma_unmap_sg_attrs); +/** + * pci_p2pdma_map_segment - map an sg segment determining the mapping type + * @state: State structure that should be declared on the stack outside of + * the for_each_sg() loop and initialized to zero. + * @dev: DMA device that's doing the mapping operation + * @sg: scatterlist segment to map + * @attrs: dma mapping attributes + * + * This is a helper to be used by non-iommu dma_map_sg() implementations where + * the sg segment is the same for the page_link and the dma_address. + * + * Attempt to map a single segment in an SGL with the PCI bus address. + * The segment must point to a PCI P2PDMA page and thus must be + * wrapped in a is_pci_p2pdma_page(sg_page(sg)) check. + * + * Returns 1 if the segment was mapped, 0 if the segment should be mapped + * directly (or through the IOMMU) and -EREMOTEIO if the segment should not + * be mapped at all. + */ +int pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, + struct device *dev, struct scatterlist *sg, + unsigned long dma_attrs) +{ + if (state->pgmap != sg_page(sg)->pgmap) { + state->pgmap = sg_page(sg)->pgmap; + state->map = pci_p2pdma_map_type(state->pgmap, dev, dma_attrs); + state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset; + } + + switch (state->map) { + case PCI_P2PDMA_MAP_BUS_ADDR: + sg->dma_address = sg_phys(sg) + state->bus_off; + sg_dma_len(sg) = sg->length; + sg_mark_pci_p2pdma(sg); + return 1; + case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: + return 0; + default: + return -EREMOTEIO; + } +} + +/** + * pci_p2pdma_map_bus_segment - map an sg segment pre determined to + * be mapped with PCI_P2PDMA_MAP_BUS_ADDR + * @pg_sg: scatterlist segment with the page to map + * @dma_sg: scatterlist segment to assign a dma address to + * + * This is a helper for iommu dma_map_sg() implementations when the + * segment for the dma address differs from the segment containing the + * source page. + * + * pci_p2pdma_map_type() must have already been called on the pg_sg and + * returned PCI_P2PDMA_MAP_BUS_ADDR. + */ +void pci_p2pdma_map_bus_segment(struct scatterlist *pg_sg, + struct scatterlist *dma_sg) +{ + struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(sg_page(pg_sg)->pgmap); + + dma_sg->dma_address = sg_phys(pg_sg) + pgmap->bus_offset; + sg_dma_len(dma_sg) = pg_sg->length; + sg_mark_pci_p2pdma(dma_sg); +} + /** * pci_p2pdma_enable_store - parse a configfs/sysfs attribute store * to enable p2pdma diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h index a06072ac3a52..49e7679403cf 100644 --- a/include/linux/pci-p2pdma.h +++ b/include/linux/pci-p2pdma.h @@ -13,6 +13,12 @@ #include +struct pci_p2pdma_map_state { + struct dev_pagemap *pgmap; + int map; + u64 bus_off; +}; + struct block_device; struct scatterlist; @@ -43,6 +49,11 @@ 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, int nents, enum dma_data_direction dir, unsigned long attrs); +int pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, + struct device *dev, struct scatterlist *sg, + unsigned long dma_attrs); +void pci_p2pdma_map_bus_segment(struct scatterlist *pg_sg, + struct scatterlist *dma_sg); int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev, bool *use_p2pdma); ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev, @@ -109,6 +120,16 @@ static inline void pci_p2pdma_unmap_sg_attrs(struct device *dev, unsigned long attrs) { } +static inline int pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, + struct device *dev, struct scatterlist *sg, + unsigned long dma_attrs) +{ + return 0; +} +static inline void pci_p2pdma_map_bus_segment(struct scatterlist *pg_sg, + struct scatterlist *dma_sg) +{ +} static inline int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev, bool *use_p2pdma) {