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Received: from cgy1-donard.priv.deltatee.com ([172.16.1.31]) by ale.deltatee.com with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kb56k-0002Pa-Ak; Fri, 06 Nov 2020 10:01:05 -0700 Received: from gunthorp by cgy1-donard.priv.deltatee.com with local (Exim 4.92) (envelope-from ) id 1kb56U-0004t2-LB; Fri, 06 Nov 2020 10:00:46 -0700 From: Logan Gunthorpe To: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org Cc: Stephen Bates , Christoph Hellwig , Dan Williams , Jason Gunthorpe , =?UTF-8?q?Christian=20K=C3=B6nig?= , Ira Weiny , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Logan Gunthorpe Date: Fri, 6 Nov 2020 10:00:26 -0700 Message-Id: <20201106170036.18713-6-logang@deltatee.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201106170036.18713-1-logang@deltatee.com> References: <20201106170036.18713-1-logang@deltatee.com> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, sbates@raithlin.com, hch@lst.de, jgg@ziepe.ca, christian.koenig@amd.com, dan.j.williams@intel.com, iweiny@intel.com, jhubbard@nvidia.com, ddutile@redhat.com, willy@infradead.org, daniel.vetter@ffwll.ch, logang@deltatee.com X-SA-Exim-Mail-From: gunthorp@deltatee.com Subject: [RFC PATCH 05/15] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Content-Transfer-Encoding: quoted-printable 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 support for dma_direct_map_sg() so that it can map PCI P2PDMA pages directly without a hack in the callers. This allows for heterogeneous SGLs that contain both P2PDMA and regular pages. The DMA_ATTR_P2PDMA flag is added to allow callers to indicate support for P2PDMA pages. In order for a caller to support P2PDMA pages they must ensure no segment is greater than 2GB such that the high bit of the dma length can be used as a flag to indicate a P2PDMA segment. Such code must then ensure to use sg_dma_p2pdma_len() instead of sg_dma_len() to filter out the flag. Signed-off-by: Logan Gunthorpe --- include/linux/dma-mapping.h | 11 +++++++++++ kernel/dma/direct.c | 33 +++++++++++++++++++++++++++++++-- 2 files changed, 42 insertions(+), 2 deletions(-) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 956151052d45..8d028e15b531 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -61,6 +61,17 @@ */ #define DMA_ATTR_PRIVILEGED (1UL << 9) =20 +/* + * DMA_ATTR_P2PDMA: specifies that dma_map_sg() may return p2pdma + * bus addresses. Code that specifies this must ensure to + * use sg_dma_p2pdma_len() instead of sg_dma_len() as the high + * bit of the length will indicate a P2PDMA bus address. + * + * If this attribute is not set and P2PDMA pages are encountered, + * dma_map_sg() will return an error. + */ +#define DMA_ATTR_P2PDMA (1UL << 10) + /* * A dma_addr_t can hold any valid DMA or bus address for the platform. = It can * be given to a device to use as a DMA source or target. It is specifi= c to a diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 06c111544f61..2fcb31789436 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -13,6 +13,7 @@ #include #include #include +#include #include "direct.h" =20 /* @@ -387,19 +388,47 @@ void dma_direct_unmap_sg(struct device *dev, struct= scatterlist *sgl, struct scatterlist *sg; int i; =20 - for_each_sg(sgl, sg, nents, i) + for_each_sg(sgl, sg, nents, i) { + if (attrs & DMA_ATTR_P2PDMA && sg_dma_is_p2pdma(sg)) { + sg_dma_len(sg) &=3D ~SG_P2PDMA_FLAG; + continue; + } + dma_direct_unmap_page(dev, sg->dma_address, sg_dma_len(sg), dir, attrs); + } } #endif =20 int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int n= ents, enum dma_data_direction dir, unsigned long attrs) { - int i; + struct dev_pagemap *pgmap =3D NULL; + int i, map =3D -1; struct scatterlist *sg; + u64 bus_off; =20 for_each_sg(sgl, sg, nents, i) { + if (is_pci_p2pdma_page(sg_page(sg))) { + if (sg_page(sg)->pgmap !=3D pgmap) { + pgmap =3D sg_page(sg)->pgmap; + map =3D pci_p2pdma_should_map_bus(dev, pgmap); + bus_off =3D pci_p2pdma_bus_offset(sg_page(sg)); + } + + if (map < 0 || !(attrs & DMA_ATTR_P2PDMA)) { + sg->dma_address =3D DMA_MAPPING_ERROR; + goto out_unmap; + } + + if (map) { + sg->dma_address =3D sg_phys(sg) + sg->offset - + bus_off; + sg_dma_len(sg) =3D sg->length | SG_P2PDMA_FLAG; + continue; + } + } + sg->dma_address =3D dma_direct_map_page(dev, sg_page(sg), sg->offset, sg->length, dir, attrs); if (sg->dma_address =3D=3D DMA_MAPPING_ERROR) --=20 2.20.1