Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758187AbYJNL65 (ORCPT ); Tue, 14 Oct 2008 07:58:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755552AbYJNL6c (ORCPT ); Tue, 14 Oct 2008 07:58:32 -0400 Received: from mga09.intel.com ([134.134.136.24]:59964 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755394AbYJNL62 (ORCPT ); Tue, 14 Oct 2008 07:58:28 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.33,409,1220252400"; d="scan'208";a="451009455" Date: Tue, 14 Oct 2008 19:01:57 +0800 From: Yu Zhao To: "linux-pci@vger.kernel.org" Cc: "jbarnes@virtuousgeek.org" , "randy.dunlap@oracle.com" , "grundler@parisc-linux.org" , "achiang@hp.com" , "matthew@wil.cx" , "rdreier@cisco.com" , "greg@kroah.com" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "virtualization@lists.linux-foundation.org" Subject: [PATCH 8/8 v4] PCI: document the changes Message-ID: <20081014110157.GH1734@yzhao12-linux.sh.intel.com> References: <20081014103424.GA1704@yzhao12-linux.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081014103424.GA1704@yzhao12-linux.sh.intel.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7764 Lines: 258 Create how-to for SR-IOV user and device driver developer. Signed-off-by: Yu Zhao --- Documentation/DocBook/kernel-api.tmpl | 1 + Documentation/PCI/pci-iov-howto.txt | 222 +++++++++++++++++++++++++++++++++ 2 files changed, 223 insertions(+), 0 deletions(-) create mode 100644 Documentation/PCI/pci-iov-howto.txt diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl index b7b1482..5cb6491 100644 --- a/Documentation/DocBook/kernel-api.tmpl +++ b/Documentation/DocBook/kernel-api.tmpl @@ -251,6 +251,7 @@ X!Edrivers/pci/hotplug.c --> !Edrivers/pci/probe.c !Edrivers/pci/rom.c +!Edrivers/pci/iov.c PCI Hotplug Support Library !Edrivers/pci/hotplug/pci_hotplug_core.c diff --git a/Documentation/PCI/pci-iov-howto.txt b/Documentation/PCI/pci-iov-howto.txt new file mode 100644 index 0000000..15d846d --- /dev/null +++ b/Documentation/PCI/pci-iov-howto.txt @@ -0,0 +1,222 @@ + PCI Express Single Root I/O Virtualization HOWTO + Copyright (C) 2008 Intel Corporation + + +1. Overview + +1.1 What is SR-IOV + +Single Root I/O Virtualization (SR-IOV) is a PCI Express Extended +capability which makes one physical device appear as multiple virtual +devices. The physical device is referred to as Physical Function while +the virtual devices are referred to as Virtual Functions. Allocation +of Virtual Functions can be dynamically controlled by Physical Function +via registers encapsulated in the capability. By default, this feature +is not enabled and the Physical Function behaves as traditional PCIe +device. Once it's turned on, each Virtual Function's PCI configuration +space can be accessed by its own Bus, Device and Function Number (Routing +ID). And each Virtual Function also has PCI Memory Space, which is used +to map its register set. Virtual Function device driver operates on the +register set so it can be functional and appear as a real existing PCI +device. + +2. User Guide + +2.1 How can I manage SR-IOV + +If a device supports SR-IOV, then there should be some entries under +Physical Function's PCI device directory. These entries are in directory: + - /sys/bus/pci/devices/XXXX:BB:DD.F/iov/ + (XXXX:BB:DD:F is domain:bus:dev:fun) +and + - /sys/bus/pci/devices/XXXX:BB:DD.F/iov/N + (N is VF number from 0 to initialvfs-1) + +To enable or disable SR-IOV: + - /sys/bus/pci/devices/XXXX:BB:DD.F/iov/enable + (writing 1/0 means enable/disable VFs, state change will + notify PF driver) + +To change number of Virtual Functions: + - /sys/bus/pci/devices/XXXX:BB:DD.F/iov/numvfs + (writing positive integer to this file will change NumVFs) + +The total and initial number of VFs can get from: + - /sys/bus/pci/devices/XXXX:BB:DD.F/iov/totalvfs + - /sys/bus/pci/devices/XXXX:BB:DD.F/iov/initialvfs + +The identifier of a VF that belongs to this PF can get from: + - /sys/bus/pci/devices/XXXX:BB:DD.F/iov/N/rid + +2.2 How can I use Virtual Functions + +Virtual Functions are treated as hot-plugged PCI devices in the kernel, +so they should be able to work in the same way as real PCI devices. +NOTE: Virtual Function device driver must be loaded to make it work. + + +3. Developer Guide + +3.1 SR-IOV APIs + +To register SR-IOV service, Physical Function device driver needs to call: + int pci_iov_register(struct pci_dev *dev, + int (*notify)(struct pci_dev *, u32), char **entries) + The 'notify' is a callback function that the SR-IOV code will invoke + it when events related to VFs happen (e.g. user read/write the sysfs + entries). The first argument is PF itself, the second argument is + event type and value. For now, following events type are supported: + - PCI_IOV_ENABLE: SR-IOV enable request + - PCI_IOV_DISABLE: SR-IOV disable request + - PCI_IOV_RD_CONF: read configuration + - PCI_IOV_WR_CONF: write configuration + - PCI_IOV_POST_EVENT: post event + And event values can be extract using following masks: + - PCI_IOV_VIRTFN_ID: Virtual Function Number + - PCI_IOV_NUM_VIRTFN: num of Virtual Functions + - PCI_IOV_EVENT_TYPE: event type (pre/post) + The 'entries' is is a list of sysfs entry names that will be to + created by the SR-IOV code. + +Note: entries could be NULL if PF driver doesn't want to create new entries +under /sys/bus/pci/devices/XXXX:BB:DD.F/iov/N/. + +To unregister SR-IOV service, Physical Function device driver needs to call: + void pci_iov_unregister(struct pci_dev *dev) + +To enable SR-IOV, Physical Function device driver needs to call: + int pci_iov_enable(struct pci_dev *dev, int numvfs) + 'numvfs' is the number of VFs that PF wants to enable. + +To disable SR-IOV, Physical Function device driver needs to call: + void pci_iov_disable(struct pci_dev *dev) + +Note: above two functions sleeps 1 second waiting on hardware transaction +completion according to SR-IOV specification. + +To read or write VFs configuration: + - int pci_iov_read_config(struct pci_dev *dev, int vfn, + char *entry, char *buf, int size); + - int pci_iov_write_config(struct pci_dev *dev, int vfn, + char *entry, char *buf); +3.2 Usage example + +Following piece of code illustrates the usage of APIs above. + +static char *entries[] = { "foo", "bar", NULL }; + +static int callback(struct pci_dev *dev, u32 event) +{ + int err; + int vfn; + int numvfs; + + if (event & PCI_IOV_ENABLE) { + /* + * request to enable SR-IOV, NumVFs is available. + * Note: if the PF want to support PM, it has to + * check the device power state here to see if + * the request is allowed or not. + */ + + numvfs = event & PCI_IOV_NUM_VIRTFN; + + } else if (event & PCI_IOV_DISABLE) { + /* + * request to disable SR-IOV. + */ + ... + + } else if (event & PCI_IOV_RD_CONF) { + /* + * request to read VF configuration, Virtual + * Function Number is available. + */ + + vfn = event & PCI_IOV_VIRTFN_ID; + + /* pass the config to SR-IOV code so user can read it */ + err = pci_iov_write_config(dev, vfn, entry, buf); + + } else if (event & PCI_IOV_WR_CONF) { + /* + * request to write VF configuration, Virtual + * Function Number is available. + */ + + vfn = event & PCI_IOV_VIRTFN_ID; + + /* read the config that has been written by user */ + err = pci_iov_read_config(dev, vfn, entry, buf, size); + + } else + return -EINVAL; + + return err; +} + +static int __devinit dev_probe(struct pci_dev *dev, + const struct pci_device_id *id) +{ + int err; + + err = pci_iov_register(dev, callback, entries); + ... + + err = pci_iov_enable(dev, nr_virtfn, callback); + + ... + + return err; +} + +static void __devexit dev_remove(struct pci_dev *dev) +{ + ... + + pci_iov_disable(dev); + + ... + + pci_iov_unregister(dev); + + ... +} + +#ifdef CONFIG_PM +/* + * If Physical Function supports the power management, then the + * SR-IOV needs to be disabled before the adapter goes to sleep, + * because Virtual Functions will not work when the adapter is in + * the power-saving mode. + * The SR-IOV can be enabled again after the adapter wakes up. + */ +static int dev_suspend(struct pci_dev *dev, pm_message_t state) +{ + ... + + pci_iov_disable(dev); + + ... +} + +static int dev_resume(struct pci_dev *dev) +{ + ... + + pci_iov_enable(dev, numvfs); + + ... +} +#endif + +static struct pci_driver dev_driver = { + .name = "SR-IOV Physical Function driver", + .id_table = dev_id_table, + .probe = dev_probe, + .remove = __devexit_p(dev_remove), +#ifdef CONFIG_PM + .suspend = dev_suspend, + .resume = dev_resume, +#endif +}; -- 1.5.6.4 -- 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/