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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 | }; | ||