git://bbs.cooldavid.org / net-next-2.6.git / blame
| Commit | Line | Data |
|---|---|---|
| 15b49bee YZ |
1 | PCI Express I/O Virtualization Howto |
| 2 | Copyright (C) 2009 Intel Corporation | |
| 3 | Yu Zhao <yu.zhao@intel.com> | |
| 4 | ||
| 5 | ||
| 6 | 1. Overview | |
| 7 | ||
| 8 | 1.1 What is SR-IOV | |
| 9 | ||
| 10 | Single Root I/O Virtualization (SR-IOV) is a PCI Express Extended | |
| 11 | capability which makes one physical device appear as multiple virtual | |
| 12 | devices. The physical device is referred to as Physical Function (PF) | |
| 13 | while the virtual devices are referred to as Virtual Functions (VF). | |
| 14 | Allocation of the VF can be dynamically controlled by the PF via | |
| 15 | registers encapsulated in the capability. By default, this feature is | |
| 16 | not enabled and the PF behaves as traditional PCIe device. Once it's | |
| 17 | turned on, each VF's PCI configuration space can be accessed by its own | |
| 18 | Bus, Device and Function Number (Routing ID). And each VF also has PCI | |
| 19 | Memory Space, which is used to map its register set. VF device driver | |
| 20 | operates on the register set so it can be functional and appear as a | |
| 21 | real existing PCI device. | |
| 22 | ||
| 23 | 2. User Guide | |
| 24 | ||
| 25 | 2.1 How can I enable SR-IOV capability | |
| 26 | ||
| 27 | The device driver (PF driver) will control the enabling and disabling | |
| 28 | of the capability via API provided by SR-IOV core. If the hardware | |
| 29 | has SR-IOV capability, loading its PF driver would enable it and all | |
| 30 | VFs associated with the PF. | |
| 31 | ||
| 32 | 2.2 How can I use the Virtual Functions | |
| 33 | ||
| 34 | The VF is treated as hot-plugged PCI devices in the kernel, so they | |
| 35 | should be able to work in the same way as real PCI devices. The VF | |
| 36 | requires device driver that is same as a normal PCI device's. | |
| 37 | ||
| 38 | 3. Developer Guide | |
| 39 | ||
| 40 | 3.1 SR-IOV API | |
| 41 | ||
| 42 | To enable SR-IOV capability: | |
| 43 | int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn); | |
| 44 | 'nr_virtfn' is number of VFs to be enabled. | |
| 45 | ||
| 46 | To disable SR-IOV capability: | |
| 47 | void pci_disable_sriov(struct pci_dev *dev); | |
| 48 | ||
| 49 | To notify SR-IOV core of Virtual Function Migration: | |
| 50 | irqreturn_t pci_sriov_migration(struct pci_dev *dev); | |
| 51 | ||
| 52 | 3.2 Usage example | |
| 53 | ||
| 54 | Following piece of code illustrates the usage of the SR-IOV API. | |
| 55 | ||
| 56 | static int __devinit dev_probe(struct pci_dev *dev, const struct pci_device_id *id) | |
| 57 | { | |
| 58 | pci_enable_sriov(dev, NR_VIRTFN); | |
| 59 | ||
| 60 | ... | |
| 61 | ||
| 62 | return 0; | |
| 63 | } | |
| 64 | ||
| 65 | static void __devexit dev_remove(struct pci_dev *dev) | |
| 66 | { | |
| 67 | pci_disable_sriov(dev); | |
| 68 | ||
| 69 | ... | |
| 70 | } | |
| 71 | ||
| 72 | static int dev_suspend(struct pci_dev *dev, pm_message_t state) | |
| 73 | { | |
| 74 | ... | |
| 75 | ||
| 76 | return 0; | |
| 77 | } | |
| 78 | ||
| 79 | static int dev_resume(struct pci_dev *dev) | |
| 80 | { | |
| 81 | ... | |
| 82 | ||
| 83 | return 0; | |
| 84 | } | |
| 85 | ||
| 86 | static void dev_shutdown(struct pci_dev *dev) | |
| 87 | { | |
| 88 | ... | |
| 89 | } | |
| 90 | ||
| 91 | static struct pci_driver dev_driver = { | |
| 92 | .name = "SR-IOV Physical Function driver", | |
| 93 | .id_table = dev_id_table, | |
| 94 | .probe = dev_probe, | |
| 95 | .remove = __devexit_p(dev_remove), | |
| 96 | .suspend = dev_suspend, | |
| 97 | .resume = dev_resume, | |
| 98 | .shutdown = dev_shutdown, | |
| 99 | }; |