From patchwork Fri Jan 28 00:25:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Logan Gunthorpe X-Patchwork-Id: 12727651 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BED5DC35270 for ; Fri, 28 Jan 2022 00:26:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344560AbiA1A0a (ORCPT ); Thu, 27 Jan 2022 19:26:30 -0500 Received: from ale.deltatee.com ([204.191.154.188]:46960 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232332AbiA1A00 (ORCPT ); Thu, 27 Jan 2022 19:26:26 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:MIME-Version:References:In-Reply-To: Message-Id:Date:Cc:To:From:content-disposition; bh=rs0zdLb19gC/hi9gcePRI1HlpCpDH9cKr/rV+O/g6PI=; b=BqqxQzy6I+a6VISPJzx9XqEL9k OP7HDA2YovJANZLSQ7Z4l/US+dxVgLkCa1dQQeu3MorRsjxynTmtGjQ+FWTR/w9EtwT+sW087npWh RpeKkJGFVw0CcB7A8t++0OeVZaCisfZQ6XfWk9NiBLaGP3aUtBLMp4CQrnvredRgsIgP4DWQMIOjN b/f49PK9y6KBoGB36zSvStK9i1ho40q4bBxV65AzIK8GfZ5ftCI5Il/FNIsgj9WJdsjg4lK5Kl3ee KeFEkjYMxkz8zvkGXIn4EqwCUotBUKsZWjOo2psRUDI+OfTVcJANPDDUt5de7J+FW8LquV1P0IGS9 c8eNbSpg==; Received: from cgy1-donard.priv.deltatee.com ([172.16.1.31]) by ale.deltatee.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nDF5p-005OcZ-LW; Thu, 27 Jan 2022 17:26:23 -0700 Received: from gunthorp by cgy1-donard.priv.deltatee.com with local (Exim 4.94.2) (envelope-from ) id 1nDF5m-0001cI-IR; Thu, 27 Jan 2022 17:26:18 -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_K=C3=B6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni , Ralph Campbell , Logan Gunthorpe , Chaitanya Kulkarni Date: Thu, 27 Jan 2022 17:25:53 -0700 Message-Id: <20220128002614.6136-4-logang@deltatee.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220128002614.6136-1-logang@deltatee.com> References: <20220128002614.6136-1-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, ddutile@redhat.com, willy@infradead.org, daniel.vetter@ffwll.ch, jason@jlekstrand.net, dave.hansen@linux.intel.com, helgaas@kernel.org, dan.j.williams@intel.com, andrzej.jakowski@intel.com, dave.b.minturn@intel.com, jianxin.xiong@intel.com, ira.weiny@intel.com, robin.murphy@arm.com, martin.oliveira@eideticom.com, ckulkarnilinux@gmail.com, logang@deltatee.com, jhubbard@nvidia.com, rcampbell@nvidia.com, kch@nvidia.com X-SA-Exim-Mail-From: gunthorp@deltatee.com Subject: [PATCH v5 03/24] lib/scatterlist: add flag for indicating P2PDMA segments in an SGL X-SA-Exim-Version: 4.2.1 (built Sat, 13 Feb 2021 17:57:42 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Make use of the third free LSB in scatterlist's page_link on 64bit systems. The extra bit 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. Create a CONFIG_NEED_SG_DMA_BUS_ADDR_FLAG bool which depends on CONFIG_64BIT (so there is space in the page link for the new flag). CONFIG_PCI_P2PDMA will then depend on this so 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: Chaitanya Kulkarni --- drivers/pci/Kconfig | 5 +++++ include/linux/scatterlist.h | 44 ++++++++++++++++++++++++++++++++++++- 2 files changed, 48 insertions(+), 1 deletion(-) diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig index d98fafdd0f99..3e837d9e1600 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..6561ca8aead8 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -64,12 +64,24 @@ struct sg_append_table { #define SG_CHAIN 0x01UL #define SG_END 0x02UL +/* + * bit 2 is the third free bit in the page_link on 64bit systems which + * is used by dma_unmap_sg() to determine if the dma_address is a + * bus address when doing P2PDMA. + */ +#ifdef CONFIG_PCI_P2PDMA +#define SG_DMA_BUS_ADDRESS 0x04UL +static_assert(__alignof__(struct page) >= 8); +#else +#define SG_DMA_BUS_ADDRESS 0x00UL +#endif + /* * We overload the LSB of the page pointer to indicate whether it's * a valid sg entry, or whether it points to the start of a new scatterlist. * Those low bits are there for everyone! (thanks mason :-) */ -#define SG_PAGE_LINK_MASK (SG_CHAIN | SG_END) +#define SG_PAGE_LINK_MASK (SG_CHAIN | SG_END | SG_DMA_BUS_ADDRESS) static inline unsigned int __sg_flags(struct scatterlist *sg) { @@ -91,6 +103,11 @@ static inline bool sg_is_last(struct scatterlist *sg) return __sg_flags(sg) & SG_END; } +static inline bool sg_is_dma_bus_address(struct scatterlist *sg) +{ + return __sg_flags(sg) & SG_DMA_BUS_ADDRESS; +} + /** * sg_assign_page - Assign a given page to an SG entry * @sg: SG entry @@ -245,6 +262,31 @@ static inline void sg_unmark_end(struct scatterlist *sg) sg->page_link &= ~SG_END; } +/** + * sg_dma_mark_bus address - Mark the scatterlist entry as a bus address + * @sg: SG entryScatterlist + * + * Description: + * Marks the passed in sg entry to indicate that the dma_address is + * a bus address and doesn't need to be unmapped. + **/ +static inline void sg_dma_mark_bus_address(struct scatterlist *sg) +{ + sg->page_link |= SG_DMA_BUS_ADDRESS; +} + +/** + * sg_unmark_pci_p2pdma - Unmark the scatterlist entry as a bus address + * @sg: SG entryScatterlist + * + * Description: + * Clears the bus address mark. + **/ +static inline void sg_dma_unmark_bus_address(struct scatterlist *sg) +{ + sg->page_link &= ~SG_DMA_BUS_ADDRESS; +} + /** * sg_phys - Return physical address of an sg entry * @sg: SG entry