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b=sXE5leQLsudq7SQg22i6/SqtqWqTlyyHAQIVWH9bAO2MPQDxZa/toNj/b/aLdj1pt eJUWdsewIeS6EZkoThfFVFTy5m8l0mxx5sdQ+vBF9/SXZTcg2hsnqwgb3oNxahbY9Q oxuGoQH4WN3xjQONhDH8oS73auA1V/uQTo9nHZ/cx/E3sT0mtK+BoCLPUYd0owEJYd fjKBOzgpvUHxtDEkUtJvp5kHHi1mVDpQO/AdiuKd+z8ggrWsUkBFWGoXfUcdgeVwhr w43naidPPhLQuz6IIctO1psEPnQRXpIg3+Lpw0HqEUNsBrYGLlhV9OMeJWV08Myuy1 6a1cHGyG90F5w== From: Leon Romanovsky To: Marek Szyprowski , Jens Axboe , Christoph Hellwig , Keith Busch Cc: Jake Edge , Jonathan Corbet , Jason Gunthorpe , Zhu Yanjun , Robin Murphy , Joerg Roedel , Will Deacon , Sagi Grimberg , Bjorn Helgaas , Logan Gunthorpe , Yishai Hadas , Shameer Kolothum , Kevin Tian , Alex Williamson , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Andrew Morton , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, Niklas Schnelle , Chuck Lever , Luis Chamberlain , Matthew Wilcox , Dan Williams , Kanchan Joshi , Chaitanya Kulkarni , Leon Romanovsky Subject: [PATCH v8 01/24] PCI/P2PDMA: Refactor the p2pdma mapping helpers Date: Fri, 18 Apr 2025 09:47:31 +0300 Message-ID: X-Mailer: git-send-email 2.49.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 3441620003 X-Rspamd-Server: rspam04 X-Stat-Signature: j7f7fk85rm8sujbhnmbwnwtsfrxnffjc X-HE-Tag: 1744958894-433908 X-HE-Meta: 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 qLRvxzi/ PH9bRgN3KvEVhlaP9pbebbilHleKRigKkyNDq/6q5CA/iR1uiZL78MFb6XTL9AKLYubmARE2ZUXnphn3a+rEbW8jkiPncKS+zvQUnjFjULYBKTJqLOY/5fN315KTrBD0zYeZPqicStLTQs55JkUviqoX8/X00JK9O36ICVkcoKlOymVu7RfBYG0uPVKqPqMvCmrgQIY20yRKYNBC7exds+YHD8HicQsjVQ4419YdT3Ua4F71TvLXsqopg3hxj2B/wbpvta3jpQlz1XYn26iI37Lsq2J2vbM16+UBSSPLtPIn8bLz1vDc7E7m4Ms+9HzD2nN+y 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: List-Subscribe: List-Unsubscribe: From: Christoph Hellwig The current scheme with a single helper to determine the P2P status and map a scatterlist segment force users to always use the map_sg helper to DMA map, which we're trying to get away from because they are very cache inefficient. Refactor the code so that there is a single helper that checks the P2P state for a page, including the result that it is not a P2P page to simplify the callers, and a second one to perform the address translation for a bus mapped P2P transfer that does not depend on the scatterlist structure. Signed-off-by: Christoph Hellwig Reviewed-by: Logan Gunthorpe Acked-by: Bjorn Helgaas Signed-off-by: Leon Romanovsky --- drivers/iommu/dma-iommu.c | 47 +++++++++++++++++----------------- drivers/pci/p2pdma.c | 38 ++++----------------------- include/linux/dma-map-ops.h | 51 +++++++++++++++++++++++++++++-------- kernel/dma/direct.c | 43 +++++++++++++++---------------- 4 files changed, 91 insertions(+), 88 deletions(-) diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index cb7e29dcac15..a8f9fd93e150 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1359,7 +1359,6 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, struct scatterlist *s, *prev = NULL; int prot = dma_info_to_prot(dir, dev_is_dma_coherent(dev), attrs); struct pci_p2pdma_map_state p2pdma_state = {}; - enum pci_p2pdma_map_type map; dma_addr_t iova; size_t iova_len = 0; unsigned long mask = dma_get_seg_boundary(dev); @@ -1389,28 +1388,30 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, size_t s_length = s->length; size_t pad_len = (mask - iova_len + 1) & mask; - if (is_pci_p2pdma_page(sg_page(s))) { - map = pci_p2pdma_map_segment(&p2pdma_state, dev, s); - switch (map) { - case PCI_P2PDMA_MAP_BUS_ADDR: - /* - * iommu_map_sg() will skip this segment as - * it is marked as a bus address, - * __finalise_sg() will copy the dma address - * into the output segment. - */ - continue; - case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: - /* - * Mapping through host bridge should be - * mapped with regular IOVAs, thus we - * do nothing here and continue below. - */ - break; - default: - ret = -EREMOTEIO; - goto out_restore_sg; - } + switch (pci_p2pdma_state(&p2pdma_state, dev, sg_page(s))) { + case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: + /* + * Mapping through host bridge should be mapped with + * regular IOVAs, thus we do nothing here and continue + * below. + */ + break; + case PCI_P2PDMA_MAP_NONE: + break; + case PCI_P2PDMA_MAP_BUS_ADDR: + /* + * iommu_map_sg() will skip this segment as it is marked + * as a bus address, __finalise_sg() will copy the dma + * address into the output segment. + */ + s->dma_address = pci_p2pdma_bus_addr_map(&p2pdma_state, + sg_phys(s)); + sg_dma_len(s) = sg->length; + sg_dma_mark_bus_address(s); + continue; + default: + ret = -EREMOTEIO; + goto out_restore_sg; } sg_dma_address(s) = s_iova_off; diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 19214ec81fbb..8d955c25aed3 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -1004,40 +1004,12 @@ static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap, return type; } -/** - * pci_p2pdma_map_segment - map an sg segment determining the mapping type - * @state: State structure that should be declared 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 - * - * 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 the type of mapping used and maps the page if the type is - * PCI_P2PDMA_MAP_BUS_ADDR. - */ -enum pci_p2pdma_map_type -pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev, - struct scatterlist *sg) +void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state, + struct device *dev, struct page *page) { - if (state->pgmap != page_pgmap(sg_page(sg))) { - state->pgmap = page_pgmap(sg_page(sg)); - state->map = pci_p2pdma_map_type(state->pgmap, dev); - state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset; - } - - if (state->map == PCI_P2PDMA_MAP_BUS_ADDR) { - sg->dma_address = sg_phys(sg) + state->bus_off; - sg_dma_len(sg) = sg->length; - sg_dma_mark_bus_address(sg); - } - - return state->map; + state->pgmap = page_pgmap(page); + state->map = pci_p2pdma_map_type(state->pgmap, dev); + state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset; } /** diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h index e172522cd936..a6b09e61f1a1 100644 --- a/include/linux/dma-map-ops.h +++ b/include/linux/dma-map-ops.h @@ -443,6 +443,11 @@ enum pci_p2pdma_map_type { */ PCI_P2PDMA_MAP_UNKNOWN = 0, + /* + * Not a PCI P2PDMA transfer. + */ + PCI_P2PDMA_MAP_NONE, + /* * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will * traverse the host bridge and the host bridge is not in the @@ -471,21 +476,47 @@ enum pci_p2pdma_map_type { struct pci_p2pdma_map_state { struct dev_pagemap *pgmap; - int map; + enum pci_p2pdma_map_type map; u64 bus_off; }; -#ifdef CONFIG_PCI_P2PDMA -enum pci_p2pdma_map_type -pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev, - struct scatterlist *sg); -#else /* CONFIG_PCI_P2PDMA */ +/* helper for pci_p2pdma_state(), do not use directly */ +void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state, + struct device *dev, struct page *page); + +/** + * pci_p2pdma_state - check the P2P transfer state of a page + * @state: P2P state structure + * @dev: device to transfer to/from + * @page: page to map + * + * Check if @page is a PCI P2PDMA page, and if yes of what kind. Returns the + * map type, and updates @state with all information needed for a P2P transfer. + */ static inline enum pci_p2pdma_map_type -pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev, - struct scatterlist *sg) +pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev, + struct page *page) +{ + if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) { + if (state->pgmap != page_pgmap(page)) + __pci_p2pdma_update_state(state, dev, page); + return state->map; + } + return PCI_P2PDMA_MAP_NONE; +} + +/** + * pci_p2pdma_bus_addr_map - map a PCI_P2PDMA_MAP_BUS_ADDR P2P transfer + * @state: P2P state structure + * @paddr: physical address to map + * + * Map a physically contigous PCI_P2PDMA_MAP_BUS_ADDR transfer. + */ +static inline dma_addr_t +pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr) { - return PCI_P2PDMA_MAP_NOT_SUPPORTED; + WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR); + return paddr + state->bus_off; } -#endif /* CONFIG_PCI_P2PDMA */ #endif /* _LINUX_DMA_MAP_OPS_H */ diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index b8fe0b3d0ffb..cec43cd5ed62 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -462,34 +462,33 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents, enum dma_data_direction dir, unsigned long attrs) { struct pci_p2pdma_map_state p2pdma_state = {}; - enum pci_p2pdma_map_type map; struct scatterlist *sg; int i, ret; for_each_sg(sgl, sg, nents, i) { - if (is_pci_p2pdma_page(sg_page(sg))) { - map = pci_p2pdma_map_segment(&p2pdma_state, dev, sg); - switch (map) { - case PCI_P2PDMA_MAP_BUS_ADDR: - continue; - case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: - /* - * Any P2P mapping that traverses the PCI - * host bridge must be mapped with CPU physical - * address and not PCI bus addresses. This is - * done with dma_direct_map_page() below. - */ - break; - default: - ret = -EREMOTEIO; + switch (pci_p2pdma_state(&p2pdma_state, dev, sg_page(sg))) { + case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: + /* + * Any P2P mapping that traverses the PCI host bridge + * must be mapped with CPU physical address and not PCI + * bus addresses. + */ + break; + case PCI_P2PDMA_MAP_NONE: + sg->dma_address = dma_direct_map_page(dev, sg_page(sg), + sg->offset, sg->length, dir, attrs); + if (sg->dma_address == DMA_MAPPING_ERROR) { + ret = -EIO; goto out_unmap; } - } - - sg->dma_address = dma_direct_map_page(dev, sg_page(sg), - sg->offset, sg->length, dir, attrs); - if (sg->dma_address == DMA_MAPPING_ERROR) { - ret = -EIO; + break; + case PCI_P2PDMA_MAP_BUS_ADDR: + sg->dma_address = pci_p2pdma_bus_addr_map(&p2pdma_state, + sg_phys(sg)); + sg_dma_mark_bus_address(sg); + continue; + default: + ret = -EREMOTEIO; goto out_unmap; } sg_dma_len(sg) = sg->length; -- 2.49.0