Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1945977Ab2EKW7f (ORCPT ); Fri, 11 May 2012 18:59:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37101 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758463Ab2EKW4W (ORCPT ); Fri, 11 May 2012 18:56:22 -0400 From: Alex Williamson Subject: [PATCH 05/13] pci: New pci_acs_enabled() To: benh@kernel.crashing.org, aik@ozlabs.ru, david@gibson.dropbear.id.au, joerg.roedel@amd.com, dwmw2@infradead.org Cc: chrisw@sous-sol.org, agraf@suse.de, benve@cisco.com, aafabbri@cisco.com, B08248@freescale.com, B07421@freescale.com, avi@redhat.com, konrad.wilk@oracle.com, kvm@vger.kernel.org, qemu-devel@nongnu.org, iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, bhelgaas@google.com, alex.williamson@redhat.com Date: Fri, 11 May 2012 16:56:02 -0600 Message-ID: <20120511225602.30496.80438.stgit@bling.home> In-Reply-To: <20120511222148.30496.68571.stgit@bling.home> References: <20120511222148.30496.68571.stgit@bling.home> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2792 Lines: 88 In a PCIe environment, transactions aren't always required to reach the root bus before being re-routed. Peer-to-peer DMA may actually not be seen by the IOMMU in these cases. For IOMMU groups, we want to provide IOMMU drivers a way to detect these restrictions. Provided with a PCI device, pci_acs_enabled returns the furthest downstream device with a complete PCI ACS chain. This information can then be used in grouping to create fully isolated groups. ACS chain logic extracted from libvirt. Signed-off-by: Alex Williamson --- drivers/pci/pci.c | 43 +++++++++++++++++++++++++++++++++++++++++++ include/linux/pci.h | 1 + 2 files changed, 44 insertions(+), 0 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 111569c..d7f05ce 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2358,6 +2358,49 @@ void pci_enable_acs(struct pci_dev *dev) pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl); } +#define PCI_EXT_CAP_ACS_ENABLED (PCI_ACS_SV | PCI_ACS_RR | \ + PCI_ACS_CR | PCI_ACS_UF) + +/** + * pci_acs_enabled - test ACS support in downstream chain + * @dev: starting PCI device + * + * Returns the furthest downstream device with an unbroken ACS chain. If + * ACS is enabled throughout the chain, the returned device is the same as + * the one passed in. + */ +struct pci_dev *pci_acs_enabled(struct pci_dev *dev) +{ + struct pci_dev *acs_dev; + int pos; + u16 ctrl; + + if (!pci_is_root_bus(dev->bus)) + acs_dev = pci_acs_enabled(dev->bus->self); + else + return dev; + + /* If the chain is already broken, pass on the device */ + if (acs_dev != dev->bus->self) + return acs_dev; + + if (!pci_is_pcie(dev) || (dev->class >> 8) != PCI_CLASS_BRIDGE_PCI) + return dev; + + if (dev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM) + return dev; + + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ACS); + if (!pos) + return acs_dev; + + pci_read_config_word(dev, pos + PCI_ACS_CTRL, &ctrl); + if ((ctrl & PCI_EXT_CAP_ACS_ENABLED) != PCI_EXT_CAP_ACS_ENABLED) + return acs_dev; + + return dev; +} + /** * pci_swizzle_interrupt_pin - swizzle INTx for device behind bridge * @dev: the PCI device diff --git a/include/linux/pci.h b/include/linux/pci.h index 9910b5c..dc25da3 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1586,6 +1586,7 @@ static inline bool pci_is_pcie(struct pci_dev *dev) } void pci_request_acs(void); +struct pci_dev *pci_acs_enabled(struct pci_dev *dev); #define PCI_VPD_LRDT 0x80 /* Large Resource Data Type */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/