1 .. SPDX-License-Identifier: GPL-2.0
2 .. include:: <isonum.txt>
3
4 ====================================
5 PCI Express I/O Virtualization Howto
6 ====================================
7
8 :Copyright: |copy| 2009 Intel Corporation
9 :Authors: - Yu Zhao <yu.zhao@intel.com>
10 - Donald Dutile <ddutile@redhat.com>
11
12 Overview
13 ========
14
15 What is SR-IOV
16 --------------
17
18 Single Root I/O Virtualization (SR-IOV) is a P
19 capability which makes one physical device app
20 devices. The physical device is referred to as
21 while the virtual devices are referred to as V
22 Allocation of the VF can be dynamically contro
23 registers encapsulated in the capability. By d
24 not enabled and the PF behaves as traditional
25 turned on, each VF's PCI configuration space c
26 Bus, Device and Function Number (Routing ID).
27 Memory Space, which is used to map its registe
28 operates on the register set so it can be func
29 real existing PCI device.
30
31 User Guide
32 ==========
33
34 How can I enable SR-IOV capability
35 ----------------------------------
36
37 Multiple methods are available for SR-IOV enab
38 In the first method, the device driver (PF dri
39 enabling and disabling of the capability via A
40 If the hardware has SR-IOV capability, loading
41 enable it and all VFs associated with the PF.
42 a module parameter to be set to determine the
43 In the second method, a write to the sysfs fil
44 enable and disable the VFs associated with a P
45 enables per-PF, VF enable/disable values versu
46 which applies to all PFs of the same device.
47 PCI SRIOV core support ensures that enable/dis
48 valid to reduce duplication in multiple driver
49 checks, e.g., check numvfs == 0 if enabling VF
50 numvfs <= totalvfs.
51 The second method is the recommended method fo
52
53 How can I use the Virtual Functions
54 -----------------------------------
55
56 The VF is treated as hot-plugged PCI devices i
57 should be able to work in the same way as real
58 requires device driver that is same as a norma
59
60 Developer Guide
61 ===============
62
63 SR-IOV API
64 ----------
65
66 To enable SR-IOV capability:
67
68 (a) For the first method, in the driver::
69
70 int pci_enable_sriov(struct pci_dev *d
71
72 'nr_virtfn' is number of VFs to be enabled.
73
74 (b) For the second method, from sysfs::
75
76 echo 'nr_virtfn' > \
77 /sys/bus/pci/devices/<DOMAIN:BUS:DEVIC
78
79 To disable SR-IOV capability:
80
81 (a) For the first method, in the driver::
82
83 void pci_disable_sriov(struct pci_dev
84
85 (b) For the second method, from sysfs::
86
87 echo 0 > \
88 /sys/bus/pci/devices/<DOMAIN:BUS:DEVIC
89
90 To enable auto probing VFs by a compatible dri
91 command below before enabling SR-IOV capabilit
92 default behavior.
93 ::
94
95 echo 1 > \
96 /sys/bus/pci/devices/<DOMAIN:BUS:DEVIC
97
98 To disable auto probing VFs by a compatible dr
99 command below before enabling SR-IOV capabilit
100 entry will not affect VFs which are already pr
101 ::
102
103 echo 0 > \
104 /sys/bus/pci/devices/<DOMAIN:BUS:DEVIC
105
106 Usage example
107 -------------
108
109 Following piece of code illustrates the usage
110 ::
111
112 static int dev_probe(struct pci_dev *d
113 {
114 pci_enable_sriov(dev, NR_VIRTF
115
116 ...
117
118 return 0;
119 }
120
121 static void dev_remove(struct pci_dev
122 {
123 pci_disable_sriov(dev);
124
125 ...
126 }
127
128 static int dev_suspend(struct device *
129 {
130 ...
131
132 return 0;
133 }
134
135 static int dev_resume(struct device *d
136 {
137 ...
138
139 return 0;
140 }
141
142 static void dev_shutdown(struct pci_de
143 {
144 ...
145 }
146
147 static int dev_sriov_configure(struct
148 {
149 if (numvfs > 0) {
150 ...
151 pci_enable_sriov(dev,
152 ...
153 return numvfs;
154 }
155 if (numvfs == 0) {
156 ....
157 pci_disable_sriov(dev)
158 ...
159 return 0;
160 }
161 }
162
163 static struct pci_driver dev_driver =
164 .name = "SR-IOV Physic
165 .id_table = dev_id_table,
166 .probe = dev_probe,
167 .remove = dev_remove,
168 .driver.pm = &dev_pm_ops,
169 .shutdown = dev_shutdown,
170 .sriov_configure = dev_sriov_c
171 };
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