From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: [PATCH 05/13] pci: New pci_acs_enabled() Date: Fri, 11 May 2012 16:56:02 -0600 Message-ID: <20120511225602.30496.80438.stgit@bling.home> References: <20120511222148.30496.68571.stgit@bling.home> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120511222148.30496.68571.stgit-xdHQ/5r00wBBDLzU/O5InQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org, aik-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org, david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org, joerg.roedel-5C7GfCeVMHo@public.gmane.org, dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org Cc: kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, B07421-KZfg59tc24xl57MIdRCFDg@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, agraf-l3A5Bk7waGM@public.gmane.org, qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org, chrisw-69jw2NvuJkxg9hUCZPvPmw@public.gmane.org, B08248-KZfg59tc24xl57MIdRCFDg@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, avi-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, benve-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org List-Id: iommu@lists.linux-foundation.org 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 */