From patchwork Wed Feb 28 23:40:00 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Logan Gunthorpe X-Patchwork-Id: 10250187 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9C7EB60211 for ; Wed, 28 Feb 2018 23:43:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8F69A28E71 for ; Wed, 28 Feb 2018 23:43:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 843B128E8D; Wed, 28 Feb 2018 23:43:08 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 151BD28E71 for ; Wed, 28 Feb 2018 23:43:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965155AbeB1XlS (ORCPT ); Wed, 28 Feb 2018 18:41:18 -0500 Received: from ale.deltatee.com ([207.54.116.67]:60184 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965042AbeB1XkZ (ORCPT ); Wed, 28 Feb 2018 18:40:25 -0500 Received: from cgy1-donard.priv.deltatee.com ([172.16.1.31]) by ale.deltatee.com with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1erBKc-0003TT-OJ; Wed, 28 Feb 2018 16:40:20 -0700 Received: from gunthorp by cgy1-donard.priv.deltatee.com with local (Exim 4.89) (envelope-from ) id 1erBKZ-0005VF-K5; Wed, 28 Feb 2018 16:40:15 -0700 From: Logan Gunthorpe To: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org, linux-block@vger.kernel.org Cc: Stephen Bates , Christoph Hellwig , Jens Axboe , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , Dan Williams , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Benjamin Herrenschmidt , Alex Williamson , Logan Gunthorpe Date: Wed, 28 Feb 2018 16:40:00 -0700 Message-Id: <20180228234006.21093-5-logang@deltatee.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180228234006.21093-1-logang@deltatee.com> References: <20180228234006.21093-1-logang@deltatee.com> X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: linux-nvme@lists.infradead.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-rdma@vger.kernel.org, linux-block@vger.kernel.org, sbates@raithlin.com, hch@lst.de, axboe@kernel.dk, sagi@grimberg.me, bhelgaas@google.com, jgg@mellanox.com, maxg@mellanox.com, keith.busch@intel.com, dan.j.williams@intel.com, benh@kernel.crashing.org, jglisse@redhat.com, alex.williamson@redhat.com, logang@deltatee.com X-SA-Exim-Mail-From: gunthorp@deltatee.com Subject: [PATCH v2 04/10] PCI/P2PDMA: Clear ACS P2P flags for all devices behind switches X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP For peer-to-peer transactions to work the downstream ports in each switch must not have the ACS flags set. At this time there is no way to dynamically change the flags and update the corresponding IOMMU groups so this is done at enumeration time before the the groups are assigned. This effectively means that if CONFIG_PCI_P2PDMA is selected then all devices behind any switch will be in the same IOMMU group. Signed-off-by: Logan Gunthorpe --- drivers/pci/Kconfig | 4 ++++ drivers/pci/p2pdma.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci.c | 4 ++++ include/linux/pci-p2pdma.h | 5 +++++ 4 files changed, 57 insertions(+) diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig index 840831418cbd..a430672f0ad4 100644 --- a/drivers/pci/Kconfig +++ b/drivers/pci/Kconfig @@ -138,6 +138,10 @@ config PCI_P2PDMA it's hard to tell which support it with good performance, so at this time you will need a PCIe switch. + Enabling this option will also disable ACS on all ports behind + any PCIe switch. This effictively puts all devices behind any + switch into the same IOMMU group. + If unsure, say N. config PCI_LABEL diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 4e1c81f64b29..61af07acd21a 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -255,6 +255,50 @@ static struct pci_dev *get_upstream_bridge_port(struct pci_dev *pdev) return up2; } +/* + * pci_p2pdma_disable_acs - disable ACS flags for ports in PCI + * bridges/switches + * @pdev: device to disable ACS flags for + * + * The ACS flags for P2P Request Redirect and P2P Completion Redirect need + * to be disabled on any downstream port in any switch in order for + * the TLPs to not be forwarded up to the RC which is not what we want + * for P2P. + * + * This function is called when the devices are first enumerated and + * will result in all devices behind any switch to be in the same IOMMU + * group. At this time there is no way to "hotplug" IOMMU groups so we rely + * on this largish hammer. If you need the devices to be in separate groups + * don't enable CONFIG_PCI_P2PDMA. + * + * Returns 1 if the ACS bits for this device were cleared, otherwise 0. + */ +int pci_p2pdma_disable_acs(struct pci_dev *pdev) +{ + struct pci_dev *up; + int pos; + u16 ctrl; + + up = get_upstream_bridge_port(pdev); + if (!up) + return 0; + pci_dev_put(up); + + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_ACS); + if (!pos) + return 0; + + dev_info(&pdev->dev, "disabling ACS flags for peer-to-peer DMA\n"); + + pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl); + + ctrl &= ~(PCI_ACS_RR | PCI_ACS_CR); + + pci_write_config_word(pdev, pos + PCI_ACS_CTRL, ctrl); + + return 1; +} + static bool __upstream_bridges_match(struct pci_dev *upstream, struct pci_dev *client) { diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index f6a4dd10d9b0..95ad3cf288c8 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -2826,6 +2827,9 @@ static void pci_std_enable_acs(struct pci_dev *dev) */ void pci_enable_acs(struct pci_dev *dev) { + if (pci_p2pdma_disable_acs(dev)) + return; + if (!pci_acs_enable) return; diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h index 126eca697ab3..f537f521f60c 100644 --- a/include/linux/pci-p2pdma.h +++ b/include/linux/pci-p2pdma.h @@ -22,6 +22,7 @@ struct block_device; struct scatterlist; #ifdef CONFIG_PCI_P2PDMA +int pci_p2pdma_disable_acs(struct pci_dev *pdev); int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, u64 offset); int pci_p2pdma_add_client(struct list_head *head, struct device *dev); @@ -41,6 +42,10 @@ int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents, void pci_p2pdma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir); #else /* CONFIG_PCI_P2PDMA */ +static inline int pci_p2pdma_disable_acs(struct pci_dev *pdev) +{ + return 0; +} static inline int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, u64 offset) {