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dkim=pass header.d=deltatee.com header.s=20200525 header.b="boDw/T3O"; spf=pass (imf07.hostedemail.com: domain of gunthorp@deltatee.com designates 204.191.154.188 as permitted sender) smtp.mailfrom=gunthorp@deltatee.com; dmarc=pass (policy=none) header.from=deltatee.com X-Stat-Signature: 5cb638u64uxanfhmfa1xfbq7terotap9 X-Rspamd-Queue-Id: 8971040026 X-HE-Tag: 1657299078-689138 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: Introduce a dma_flags field in struct scatterlist. These flags will be used by dma_[un]map_sg_p2pdma() to determine when a given SGL segments dma_address points to a PCI bus address. dma_unmap_sg_p2pdma() will need to perform different cleanup when a segment is marked as a bus address. The dma_flags field will fit in the existing padding on 64BIT systems (assuming CONFIG_NEED_SG_DMA_LENGTH is also set). The new bit will only be used when CONFIG_PCI_P2PDMA is set; this means PCI P2PDMA will require CONFIG_64BIT. This should be acceptable as the majority of P2PDMA use cases are restricted to newer root complexes and roughly require the extra address space for memory BARs used in the transactions. Signed-off-by: Logan Gunthorpe Reviewed-by: Christoph Hellwig --- drivers/pci/Kconfig | 5 +++ include/linux/scatterlist.h | 69 +++++++++++++++++++++++++++++++++++++ 2 files changed, 74 insertions(+) diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig index 133c73207782..5cc7cba1941f 100644 --- a/drivers/pci/Kconfig +++ b/drivers/pci/Kconfig @@ -164,6 +164,11 @@ config PCI_PASID config PCI_P2PDMA bool "PCI peer-to-peer transfer support" depends on ZONE_DEVICE + # + # The need for the scatterlist DMA bus address flag means PCI P2PDMA + # requires 64bit + # + depends on 64BIT select GENERIC_ALLOCATOR help Enableѕ drivers to do PCI peer-to-peer transactions to and from diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 7ff9d6386c12..375a5e90d86a 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -16,6 +16,9 @@ struct scatterlist { #ifdef CONFIG_NEED_SG_DMA_LENGTH unsigned int dma_length; #endif +#ifdef CONFIG_PCI_P2PDMA + unsigned int dma_flags; +#endif }; /* @@ -245,6 +248,72 @@ static inline void sg_unmark_end(struct scatterlist *sg) sg->page_link &= ~SG_END; } +/* + * CONFGI_PCI_P2PDMA depends on CONFIG_64BIT which means there is 4 bytes + * in struct scatterlist (assuming also CONFIG_NEED_SG_DMA_LENGTH is set). + * Use this padding for DMA flags bits to indicate when a specific + * dma address is a bus address. + */ +#ifdef CONFIG_PCI_P2PDMA + +#define SG_DMA_BUS_ADDRESS (1 << 0) + +/** + * sg_dma_is_bus address - Return whether a given segment was marked + * as a bus address + * @sg: SG entry + * + * Description: + * Returns true if sg_dma_mark_bus_address() has been called on + * this segment. + **/ +static inline bool sg_is_dma_bus_address(struct scatterlist *sg) +{ + return sg->dma_flags & SG_DMA_BUS_ADDRESS; +} + +/** + * sg_dma_mark_bus address - Mark the scatterlist entry as a bus address + * @sg: SG entry + * + * Description: + * Marks the passed in sg entry to indicate that the dma_address is + * a bus address and doesn't need to be unmapped. This should only be + * used by dma_map_sg() implementations to mark bus addresses + * so they can be properly cleaned up in dma_unmap_sg(). + **/ +static inline void sg_dma_mark_bus_address(struct scatterlist *sg) +{ + sg->dma_flags |= SG_DMA_BUS_ADDRESS; +} + +/** + * sg_unmark_bus_address - Unmark the scatterlist entry as a bus address + * @sg: SG entry + * + * Description: + * Clears the bus address mark. + **/ +static inline void sg_dma_unmark_bus_address(struct scatterlist *sg) +{ + sg->dma_flags &= ~SG_DMA_BUS_ADDRESS; +} + +#else + +static inline bool sg_is_dma_bus_address(struct scatterlist *sg) +{ + return false; +} +static inline void sg_dma_mark_bus_address(struct scatterlist *sg) +{ +} +static inline void sg_dma_unmark_bus_address(struct scatterlist *sg) +{ +} + +#endif + /** * sg_phys - Return physical address of an sg entry * @sg: SG entry