Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753888AbaJGO6m (ORCPT ); Tue, 7 Oct 2014 10:58:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22065 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752281AbaJGO6k (ORCPT ); Tue, 7 Oct 2014 10:58:40 -0400 Date: Tue, 7 Oct 2014 18:02:09 +0300 From: "Michael S. Tsirkin" To: Marcel Apfelbaum Cc: linux-pci@vger.kernel.org, bhelgaas@google.com, linux-kernel@vger.kernel.org, marcel@redhat.com, alex.williamson@redhat.com Subject: Re: [PATCH v3] PCI: add kernel parameter to override devid<->driver mapping. Message-ID: <20141007150209.GB7876@redhat.com> References: <1412693312-2449-1-git-send-email-marcel.a@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1412693312-2449-1-git-send-email-marcel.a@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 07, 2014 at 05:48:32PM +0300, Marcel Apfelbaum wrote: > Scanning a lot of devices during boot requires a lot of time. > On other scenarios there is a need to bind a driver to a specific slot. > > Binding devices to pci-stub driver does not work, > as it will not differentiate between devices of the > same type. Using some start scripts is error prone. > > The solution leverages driver_override functionality introduced by > > commit: 782a985d7af26db39e86070d28f987cad21313c0 > Author: Alex Williamson > Date: Tue May 20 08:53:21 2014 -0600 > > PCI: Introduce new device binding path using pci_dev.driver_override > > In order to bind PCI slots to specific drivers use: > pci=driver[xxxx:xx:xx.x]=foo,driver[xxxx:xx:xx.x]=bar,... > > Signed-off-by: Marcel Apfelbaum > --- > v2 -> v3: > - Corrected subject line > v1 -> v2: > - Addressed Michael S. Tsirkin comments > - Removed 32 slots limitation > - Better handling of memory allocation failures > (preferred BUG_ON over error messages) > - Addressed Alex Williamson's comments: > - Modified commit message to show parameter usage more clear. > - I preferred to re-use parse_args instead of manually using > strstr in order to better comply with command line parsing > rules. > - I didn't use any locking when parsing the command line args > (see parse_done usage) assuming that first call will be > early in system boot and no race can occur. Please correct > me if I am wrong. > > Notes: > - I have further ideas on top of this patch based on your reviews. > I thought of: > - Use wildcards to specify entire buses/devices, something like: > driver[0001:02:*.*]=pci-stub > - Use comma to separate several devices: > driver[0001:02:03.4,0001:02:04.0,...]=pci-stub > - Make domain optional: > driver[00:03.0]=pci-stub > > Comments will be appreciated, > Thanks, > Marcel > Documentation/kernel-parameters.txt | 4 ++ > drivers/pci/bus.c | 86 +++++++++++++++++++++++++++++++++++++ > drivers/pci/pci.c | 2 + > 3 files changed, 92 insertions(+) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 5ae8608..c1cbb4c 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -2631,6 +2631,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > pcie_scan_all Scan all possible PCIe devices. Otherwise we > only look for one device below a PCIe downstream > port. > + driver Provide an override to the devid<->driver mapping > + for a specific slot. > + Bind PCI slot 0001:02:03.4 to pci-stub by: > + driver[0001:02:03.4]=pci-stub > > pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power > Management. > diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c > index 73aef51..d2c0721 100644 > --- a/drivers/pci/bus.c > +++ b/drivers/pci/bus.c > @@ -230,6 +230,91 @@ EXPORT_SYMBOL(pci_bus_alloc_resource); > > void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { } > > +#define DRIVER_OVERRIDE_NAME_LENGTH 64 Do we know all drivers have shorter names? > + > +struct driver_override_entry { > + unsigned int domain; > + unsigned char bus; > + unsigned int devfn; > + char driver_name[DRIVER_OVERRIDE_NAME_LENGTH]; > + struct list_head list; > +}; > + > +static LIST_HEAD(driver_override_entries); > + > +static int pci_device_parse_driver_override(char *param, char *val, > + const char *unused) > +{ > + unsigned int domain, bus, dev, fn; > + char driver_name[DRIVER_OVERRIDE_NAME_LENGTH]; > + char format[] = "[%4x:%2x:%2x.%2x]=%%%ds"; > + struct driver_override_entry *entry; > + int ret; > + > + while (val) { > + char *k = strchr(val, ','); > + > + if (k) > + *k++ = 0; > + > + if (strncmp(val, "driver", 6)) { > + val = k; > + continue; > + } > + > + sprintf(format + 18, "%%%ds", DRIVER_OVERRIDE_NAME_LENGTH); > + ret = sscanf(val + 6, format, &domain, &bus, &dev, &fn, > + driver_name); > + if (ret != 5) { > + pr_err("PCI: Invalid command line: %s\n", val); > + val = k; > + continue; > + } > + > + entry = kzalloc(sizeof(*entry), GFP_KERNEL); > + BUG_ON(!entry); > + > + INIT_LIST_HEAD(&entry->list); > + entry->domain = domain; > + entry->bus = bus && 0xff; > + entry->devfn = ((dev & 0x1f) << 3) | (fn & 0x7); > + memcpy(entry->driver_name, driver_name, sizeof(driver_name)); > + > + list_add_tail(&entry->list, &driver_override_entries); > + val = k; > + } > + > + return 0; > +} > + > +static void pci_device_setup_driver_override(struct pci_dev *dev) > +{ > + static int parse_done; > + struct driver_override_entry *entry; > + > + if (!parse_done) { > + char *cmdline = kstrdup(saved_command_line, GFP_KERNEL); > + > + BUG_ON(!cmdline); > + > + parse_args("pci", cmdline, NULL, > + 0, 0, 0, &pci_device_parse_driver_override); > + kfree(cmdline); > + parse_done = 1; > + } > + > + list_for_each_entry(entry, &driver_override_entries, list) { > + if (pci_domain_nr(dev->bus) != entry->domain || > + dev->bus->number != entry->bus || > + dev->devfn != entry->devfn) > + continue; > + > + dev->driver_override = kstrdup(entry->driver_name, GFP_KERNEL); > + BUG_ON(!dev->driver_override); > + break; > + } > +} > + > /** > * pci_bus_add_device - start driver for a single device > * @dev: device to add > @@ -245,6 +330,7 @@ void pci_bus_add_device(struct pci_dev *dev) > * are not assigned yet for some devices. > */ > pci_fixup_device(pci_fixup_final, dev); > + pci_device_setup_driver_override(dev); > pci_create_sysfs_dev_files(dev); > pci_proc_attach_device(dev); > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index b7678be..6bd7844 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -4468,6 +4468,8 @@ static int __init pci_setup(char *str) > pcie_bus_config = PCIE_BUS_PEER2PEER; > } else if (!strncmp(str, "pcie_scan_all", 13)) { > pci_add_flags(PCI_SCAN_ALL_PCIE_DEVS); > + } else if (!strncmp(str, "driver", 6)) { > + /* lazy evaluation by the pci subsystem */ > } else { > printk(KERN_ERR "PCI: Unknown option `%s'\n", > str); > -- > 1.8.3.1 -- 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/