From patchwork Thu May 31 23:50:09 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Logan Gunthorpe X-Patchwork-Id: 10442141 X-Patchwork-Delegate: bhelgaas@google.com 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 84809602BF for ; Thu, 31 May 2018 23:50:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 758D728F6A for ; Thu, 31 May 2018 23:50:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 69F0C28F9E; Thu, 31 May 2018 23:50:49 +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=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham 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 816B328F70 for ; Thu, 31 May 2018 23:50:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750869AbeEaXud (ORCPT ); Thu, 31 May 2018 19:50:33 -0400 Received: from ale.deltatee.com ([207.54.116.67]:59078 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750737AbeEaXu2 (ORCPT ); Thu, 31 May 2018 19:50:28 -0400 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 1fOXKp-00075E-F7; Thu, 31 May 2018 17:50:25 -0600 Received: from gunthorp by cgy1-donard.priv.deltatee.com with local (Exim 4.89) (envelope-from ) id 1fOXKf-0001Ny-5F; Thu, 31 May 2018 17:50:13 -0600 From: Logan Gunthorpe To: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-doc@vger.kernel.org Cc: Stephen Bates , Christoph Hellwig , Bjorn Helgaas , Jonathan Corbet , Ingo Molnar , Thomas Gleixner , "Paul E. McKenney" , Marc Zyngier , Kai-Heng Feng , Frederic Weisbecker , Dan Williams , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Benjamin Herrenschmidt , Alex Williamson , =?UTF-8?q?Christian=20K=C3=B6nig?= , Logan Gunthorpe Date: Thu, 31 May 2018 17:50:09 -0600 Message-Id: <20180531235010.5279-3-logang@deltatee.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180531235010.5279-1-logang@deltatee.com> References: <20180531235010.5279-1-logang@deltatee.com> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-doc@vger.kernel.org, sbates@raithlin.com, hch@lst.de, bhelgaas@google.com, corbet@lwn.net, tglx@linutronix.de, paulmck@linux.vnet.ibm.com, marc.zyngier@arm.com, kai.heng.feng@canonical.com, mingo@kernel.org, frederic@kernel.org, dan.j.williams@intel.com, benh@kernel.crashing.org, jglisse@redhat.com, alex.williamson@redhat.com, christian.koenig@amd.com, logang@deltatee.com X-SA-Exim-Mail-From: gunthorp@deltatee.com Subject: [PATCH v2 2/3] PCI: Allow specifying devices using a base bus and path of devfns 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-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When specifying PCI devices on the kernel command line using a BDF, the bus numbers can change when adding or replacing a device, changing motherboard firmware, or applying kernel parameters like pci=assign-buses. When this happens, it is usually undesirable to apply whatever command line tweak to the wrong device. Therefore, it is useful to be able to specify devices with a base bus number and the path of devfns needed to get to it. (Similar to the "device scope" structure in the Intel VT-d spec, Section 8.3.1.) Thus, we add an option to specify devices in the following format: path:[:]:./.[/ ...] The path can be any segment within the PCI hierarchy of any length and determined through the use of 'lspci -t'. When specified this way, it is less likely that a renumbered bus will result in a valid device specification and the tweak won't be applied to the wrong device. Signed-off-by: Logan Gunthorpe Reviewed-by: Stephen Bates Acked-by: Christian König --- Documentation/admin-guide/kernel-parameters.txt | 12 ++- drivers/pci/pci.c | 101 +++++++++++++++++++++++- 2 files changed, 107 insertions(+), 6 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index e58cc671ff92..bc51b316f485 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2989,9 +2989,10 @@ Some options herein operate on a specific device or a set of devices (). These are - specified in one of two formats: + specified in one of three formats: [:]:. + path:[:]:./.[/ ...] pci::[::] Note: the first format specifies a PCI @@ -2999,9 +3000,12 @@ if new hardware is inserted, if motherboard firmware changes, or due to changes caused by other kernel parameters. The second format - selects devices using IDs from the - configuration space which may match multiple - devices in the system. + specifies a path from a device through + a path of multiple slot/function addresses + (this is more robust against renumbering + issues). The third format selects devices using + IDs from the configuration space which may match + multiple devices in the system. earlydump [X86] dump PCI config space before the kernel changes anything diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 85fec5e2640b..39f11bd0ee03 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -184,22 +184,111 @@ EXPORT_SYMBOL_GPL(pci_ioremap_wc_bar); #endif /** + * pci_dev_str_match_path - test if a path string matches a device + * @dev: the PCI device to test + * @p: string to match the device against + * @endptr: pointer to the string after the match + * + * Test if a string (typically from a kernel parameter) formated as a + * path of slot/function addresses matches a PCI device. The string must + * be of the form: + * + * [:]:./.[/ ...] + * + * A path for a device can be obtained using 'lspci -t'. Using a path + * is more robust against renumbering of devices than using only + * a single bus, slot and function address. + * + * Returns 1 if the string matches the device, 0 if it does not and + * a negative error code if it fails to parse the string. + */ +static int pci_dev_str_match_path(struct pci_dev *dev, const char *path, + const char **endptr) +{ + int ret; + int seg, bus, slot, func; + char *wpath, *p; + char end; + + *endptr = strchrnul(path, ';'); + + wpath = kmemdup_nul(path, *endptr - path, GFP_KERNEL); + if (!wpath) + return -ENOMEM; + + while (1) { + p = strrchr(wpath, '/'); + if (!p) + break; + ret = sscanf(p, "/%x.%x%c", &slot, &func, &end); + if (ret != 2) { + ret = -EINVAL; + goto free_and_exit; + } + + if (dev->devfn != PCI_DEVFN(slot, func)) { + ret = 0; + goto free_and_exit; + } + + /* + * Note: we don't need to get a reference to the upstream + * bridge because we hold a reference to the top level + * device which should hold a reference to the bridge, + * and so on. + */ + dev = pci_upstream_bridge(dev); + if (!dev) { + ret = 0; + goto free_and_exit; + } + + *p = 0; + } + + ret = sscanf(wpath, "%x:%x:%x.%x%c", &seg, &bus, &slot, + &func, &end); + if (ret != 4) { + seg = 0; + ret = sscanf(wpath, "%x:%x.%x%c", &bus, &slot, &func, &end); + if (ret != 3) { + ret = -EINVAL; + goto free_and_exit; + } + } + + ret = (seg == pci_domain_nr(dev->bus) && + bus == dev->bus->number && + dev->devfn == PCI_DEVFN(slot, func)); + +free_and_exit: + kfree(wpath); + return ret; +} + +/** * pci_dev_str_match - test if a string matches a device * @dev: the PCI device to test * @p: string to match the device against * @endptr: pointer to the string after the match * * Test if a string (typically from a kernel parameter) matches a - * specified. The string may be of one of two forms formats: + * specified. The string may be of one of three formats: * * [:]:. + * path:[:]:./.[/ ...] * pci::[::] * * The first format specifies a PCI bus/slot/function address which * may change if new hardware is inserted, if motherboard firmware changes, * or due to changes caused in kernel parameters. * - * The second format matches devices using IDs in the configuration + * The second format specifies a PCI bus/slot/function root address and + * a path of slot/function addresses to the specific device from the root. + * The path for a device can be determined through the use of 'lspci -t'. + * This format is more robust against renumbering issues than the first format. + + * The third format matches devices using IDs in the configuration * space which may match multiple devices in the system. A value of 0 * for any field will match all devices. * @@ -236,7 +325,15 @@ static int pci_dev_str_match(struct pci_dev *dev, const char *p, (!subsystem_device || subsystem_device == dev->subsystem_device)) goto found; + } else if (strncmp(p, "path:", 5) == 0) { + /* PCI Root Bus and a path of Slot,Function IDs */ + p += 5; + ret = pci_dev_str_match_path(dev, p, &p); + if (ret < 0) + return ret; + else if (ret) + goto found; } else { /* PCI Bus,Slot,Function ids are specified */ ret = sscanf(p, "%x:%x:%x.%x%n", &seg, &bus, &slot,