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docs: Convert 'drvnodedev' page to rST
Fix one cross link anchor along with the conversion. Signed-off-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Erik Skultety <eskultet@redhat.com>
This commit is contained in:
Peter Krempa
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html>
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<html xmlns="http://www.w3.org/1999/xhtml">
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<body>
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<h1>Host device management</h1>
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<p>
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Libvirt provides management of both physical and virtual host devices
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(historically also referred to as node devices) like USB, PCI, SCSI, and
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network devices. This also includes various virtualization capabilities
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which the aforementioned devices provide for utilization, for example
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SR-IOV, NPIV, MDEV, DRM, etc.
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</p>
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<p>
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The node device driver provides means to list and show details about host
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devices (<code>virsh nodedev-list</code>, <code>virsh nodedev-info</code>,
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and <code>virsh nodedev-dumpxml</code>), which are generic and can be used
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with all devices. It also provides the means to manage virtual devices.
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Persistently-defined virtual devices are only supported for mediated
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devices, while transient devices are supported by both mediated devices
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and NPIV (<a href="https://wiki.libvirt.org/page/NPIV_in_libvirt">more
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info about NPIV)</a>).
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</p>
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<p>
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Persistent virtual devices are managed with
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<code>virsh nodedev-define</code> and <code>virsh nodedev-undefine</code>.
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Persistent devices can be configured to start manually or automatically
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using <code>virsh nodedev-autostart</code>. Inactive devices can be made
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active with <code>virsh nodedev-start</code>.
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</p>
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<p>
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Transient virtual devices are started and stopped with the commands
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<code>virsh nodedev-create</code> and <code>virsh nodedev-destroy</code>.
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</p>
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<p>
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Devices on the host system are arranged in a tree-like hierarchy, with
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the root node being called <code>computer</code>. The node device driver
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supports udev backend (HAL backend was removed in <code>6.8.0</code>).
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</p>
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<p>
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Details of the XML format of a host device can be found <a
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href="formatnode.html">here</a>. Of particular interest is the
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<code>capability</code> element, which describes features supported by
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the device. Some specific device types are addressed in more detail
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below.
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</p>
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<h2>Basic structure of a node device</h2>
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<pre>
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<device>
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<name>pci_0000_00_17_0</name>
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<path>/sys/devices/pci0000:00/0000:00:17.0</path>
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<parent>computer</parent>
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<driver>
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<name>ahci</name>
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</driver>
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<capability type='pci'>
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...
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</capability>
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</device></pre>
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<ul id="toc"/>
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<h2><a id="PCI">PCI host devices</a></h2>
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<dl>
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<dt><code>capability</code></dt>
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<dd>
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When used as top level element, the supported values for the
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<code>type</code> attribute are <code>pci</code> and
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<code>phys_function</code> (see <a href="#SRIOVCap">SR-IOV below</a>).
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</dd>
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</dl>
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<pre>
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<device>
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<name>pci_0000_04_00_1</name>
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<path>/sys/devices/pci0000:00/0000:00:06.0/0000:04:00.1</path>
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<parent>pci_0000_00_06_0</parent>
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<driver>
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<name>igb</name>
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</driver>
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<capability type='pci'>
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<domain>0</domain>
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<bus>4</bus>
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<slot>0</slot>
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<function>1</function>
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<product id='0x10c9'>82576 Gigabit Network Connection</product>
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<vendor id='0x8086'>Intel Corporation</vendor>
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<iommuGroup number='15'>
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<address domain='0x0000' bus='0x04' slot='0x00' function='0x1'/>
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</iommuGroup>
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<numa node='0'/>
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<pci-express>
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<link validity='cap' port='1' speed='2.5' width='2'/>
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<link validity='sta' speed='2.5' width='2'/>
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</pci-express>
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</capability>
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</device></pre>
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<p>
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The XML format for a PCI device stays the same for any further
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capabilities it supports, a single nested <code><capability></code>
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element will be included for each capability the device supports.
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</p>
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<h3><a id="SRIOVCap">SR-IOV capability</a></h3>
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<p>
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Single root input/output virtualization (SR-IOV) allows sharing of the
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PCIe resources by multiple virtual environments. That is achieved by
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slicing up a single full-featured physical resource called physical
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function (PF) into multiple devices called virtual functions (VFs) sharing
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their configuration with the underlying PF. Despite the SR-IOV
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specification, the amount of VFs that can be created on a PF varies among
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manufacturers.
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</p>
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<p>
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Suppose the NIC <a href="#PCI">above</a> was also SR-IOV capable, it would
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also include a nested
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<code><capability></code> element enumerating all virtual
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functions available on the physical device (physical port) like in the
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example below.
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</p>
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<pre>
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<capability type='pci'>
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...
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<capability type='virt_functions' maxCount='7'>
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<address domain='0x0000' bus='0x04' slot='0x10' function='0x1'/>
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<address domain='0x0000' bus='0x04' slot='0x10' function='0x3'/>
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<address domain='0x0000' bus='0x04' slot='0x10' function='0x5'/>
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<address domain='0x0000' bus='0x04' slot='0x10' function='0x7'/>
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<address domain='0x0000' bus='0x04' slot='0x11' function='0x1'/>
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<address domain='0x0000' bus='0x04' slot='0x11' function='0x3'/>
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<address domain='0x0000' bus='0x04' slot='0x11' function='0x5'/>
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</capability>
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...
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</capability></pre>
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<p>
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A SR-IOV child device on the other hand, would then report its top level
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capability type as a <code>phys_function</code> instead:
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</p>
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<pre>
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<device>
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...
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<capability type='phys_function'>
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<address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
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</capability>
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...
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</device></pre>
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<h3><a id="MDEVCap">MDEV capability</a></h3>
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<p>
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A device capable of creating mediated devices will include a nested
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capability <code>mdev_types</code> which enumerates all supported mdev
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types on the physical device, along with the type attributes available
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through sysfs. A detailed description of the XML format for the
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<code>mdev_types</code> capability can be found
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<a href="formatnode.html#MDEVTypesCap">here</a>.
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</p>
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<p>
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The following example shows how we might represent an NVIDIA GPU device
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that supports mediated devices. See below for <a href="#MDEV">more
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information about mediated devices</a>.
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</p>
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<pre>
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<device>
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...
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<driver>
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<name>nvidia</name>
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</driver>
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<capability type='pci'>
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...
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<capability type='mdev_types'>
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<type id='nvidia-11'>
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<name>GRID M60-0B</name>
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<deviceAPI>vfio-pci</deviceAPI>
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<availableInstances>16</availableInstances>
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</type>
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<!-- Here would come the rest of the available mdev types -->
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</capability>
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...
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</capability>
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</device></pre>
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<h3><a id="VPDCap">VPD capability</a></h3>
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<p>
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A device that exposes a PCI/PCIe VPD capability will include a nested
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capability <code>vpd</code> which presents data stored in the Vital Product
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Data (VPD). VPD provides a device name and a number of other standard-defined
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read-only fields (change level, manufacture id, part number, serial number) and
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vendor-specific read-only fields. Additionally, if a device supports it,
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read-write fields (asset tag, vendor-specific fields or system fields) may
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also be present. The VPD capability is optional for PCI/PCIe devices and the
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set of exposed fields may vary depending on a device. The XML format follows
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the binary format described in "I.3. VPD Definitions" in PCI Local Bus (2.2+)
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and the identical format in PCIe 4.0+. At the time of writing, the support for
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exposing this capability is only present on Linux-based systems (kernel version
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v2.6.26 is the first one to expose VPD via sysfs which Libvirt relies on).
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Reading the VPD contents requires root privileges, therefore,
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<code>virsh nodedev-dumpxml</code> must be executed accordingly.
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A description of the XML format for the <code>vpd</code> capability can
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be found <a href="formatnode.html#VPDCap">here</a>.
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</p>
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<p>
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The following example shows a VPD representation for a device that exposes the
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VPD capability with read-only and read-write fields. Among other things,
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the VPD of this particular device includes a unique board serial number.
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</p>
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<pre>
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<device>
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<name>pci_0000_42_00_0</name>
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<capability type='pci'>
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<class>0x020000</class>
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<domain>0</domain>
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<bus>66</bus>
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<slot>0</slot>
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<function>0</function>
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<product id='0xa2d6'>MT42822 BlueField-2 integrated ConnectX-6 Dx network controller</product>
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<vendor id='0x15b3'>Mellanox Technologies</vendor>
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<capability type='virt_functions' maxCount='16'/>
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<capability type='vpd'>
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<name>BlueField-2 DPU 25GbE Dual-Port SFP56, Crypto Enabled, 16GB on-board DDR, 1GbE OOB management, Tall Bracket</name>
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<fields access='readonly'>
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<change_level>B1</change_level>
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<manufacture_id>foobar</manufacture_id>
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<part_number>MBF2H332A-AEEOT</part_number>
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<serial_number>MT2113X00000</serial_number>
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<vendor_field index='0'>PCIeGen4 x8</vendor_field>
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<vendor_field index='2'>MBF2H332A-AEEOT</vendor_field>
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<vendor_field index='3'>3c53d07eec484d8aab34dabd24fe575aa</vendor_field>
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<vendor_field index='A'>MLX:MN=MLNX:CSKU=V2:UUID=V3:PCI=V0:MODL=BF2H332A</vendor_field>
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</fields>
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<fields access='readwrite'>
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<asset_tag>fooasset</asset_tag>
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<vendor_field index='0'>vendorfield0</vendor_field>
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<vendor_field index='2'>vendorfield2</vendor_field>
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<vendor_field index='A'>vendorfieldA</vendor_field>
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<system_field index='B'>systemfieldB</system_field>
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<system_field index='0'>systemfield0</system_field>
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</fields>
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</capability>
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<iommuGroup number='65'>
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<address domain='0x0000' bus='0x42' slot='0x00' function='0x0'/>
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</iommuGroup>
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<numa node='0'/>
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<pci-express>
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<link validity='cap' port='0' speed='16' width='8'/>
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<link validity='sta' speed='8' width='8'/>
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</pci-express>
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</capability>
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</device>
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</pre>
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<h2><a id="MDEV">Mediated devices (MDEVs)</a></h2>
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<p>
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Mediated devices (<span class="since">Since 3.2.0</span>) are software
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devices defining resource allocation on the backing physical device which
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in turn allows the parent physical device's resources to be divided into
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several mediated devices, thus sharing the physical device's performance
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among multiple guests. Unlike SR-IOV however, where a PCIe device appears
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as multiple separate PCIe devices on the host's PCI bus, mediated devices
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only appear on the mdev virtual bus. Therefore, no detach/reattach
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procedure from/to the host driver procedure is involved even though
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mediated devices are used in a direct device assignment manner. A
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detailed description of the XML format for the <code>mdev</code>
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capability can be found <a href="formatnode.html#mdev">here</a>.
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</p>
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<h3>Example of a mediated device</h3>
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<pre>
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<device>
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<name>mdev_4b20d080_1b54_4048_85b3_a6a62d165c01</name>
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<path>/sys/devices/pci0000:00/0000:00:02.0/4b20d080-1b54-4048-85b3-a6a62d165c01</path>
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<parent>pci_0000_06_00_0</parent>
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<driver>
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<name>vfio_mdev</name>
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</driver>
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<capability type='mdev'>
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<type id='nvidia-11'/>
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<uuid>4b20d080-1b54-4048-85b3-a6a62d165c01</uuid>
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<iommuGroup number='12'/>
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</capability>
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</device></pre>
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<p>
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The support of mediated device's framework in libvirt's node device driver
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covers the following features:
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</p>
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<ul>
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<li>
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list available mediated devices on the host
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(<span class="since">Since 3.4.0</span>)
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</li>
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<li>
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display device details
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(<span class="since">Since 3.4.0</span>)
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</li>
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<li>
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create transient mediated devices
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(<span class="since">Since 6.5.0</span>)
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</li>
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<li>
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define persistent mediated devices
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(<span class="since">Since 7.3.0</span>)
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</li>
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</ul>
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<p>
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Because mediated devices are instantiated from vendor specific templates,
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simply called 'types', information describing these types is contained
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within the parent device's capabilities (see the example in <a
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href="#PCI">PCI host devices</a>). To list all devices capable of
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creating mediated devices, the following command can be used.
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</p>
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<pre>$ virsh nodedev-list --cap mdev_types</pre>
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<p>
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To see the supported mediated device types on a specific physical device
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use the following:
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</p>
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||||
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<pre>$ virsh nodedev-dumpxml <device></pre>
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<p>
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||||
Before creating a mediated device, unbind the device from the respective
|
||||
device driver, eg. subchannel I/O driver for a CCW device. Then bind the
|
||||
device to the respective VFIO driver. For a CCW device, also unbind the
|
||||
corresponding subchannel of the CCW device from the subchannel I/O driver
|
||||
and then bind the subchannel (instead of the CCW device) to the vfio_ccw
|
||||
driver. The below example shows the unbinding and binding steps for a CCW
|
||||
device.
|
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</p>
|
||||
|
||||
<pre>
|
||||
device="0.0.1234"
|
||||
subchannel="0.0.0123"
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||||
echo $device > /sys/bus/ccw/devices/$device/driver/unbind
|
||||
echo $subchannel > /sys/bus/css/devices/$subchannel/driver/unbind
|
||||
echo $subchannel > /sys/bus/css/drivers/vfio_ccw/bind
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
To instantiate a transient mediated device, create an XML file representing the
|
||||
device. See above for information about the mediated device xml format.
|
||||
</p>
|
||||
|
||||
<pre>$ virsh nodedev-create <xml-file>
|
||||
Node device '<device-name>' created from '<xml-file>'</pre>
|
||||
|
||||
<p>
|
||||
If you would like to persistently define the device so that it will be
|
||||
maintained across host reboots, use <code>virsh nodedev-define</code>
|
||||
instead of <code>nodedev-create</code>:
|
||||
</p>
|
||||
|
||||
<pre>$ virsh nodedev-define <xml-file>
|
||||
Node device '<device-name>' defined from '<xml-file>'</pre>
|
||||
|
||||
<p>
|
||||
To start an instance of this device definition, use the following command:
|
||||
</p>
|
||||
|
||||
<pre>$ virsh nodedev-start <device-name></pre>
|
||||
<p>
|
||||
Active mediated device instances can be stopped using <code>virsh
|
||||
nodedev-destroy</code>, and persistent device definitions can be removed
|
||||
using <code>virsh nodedev-undefine</code>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
If a mediated device is defined persistently, it can also be set to be
|
||||
automatically started whenever the host reboots or when the parent device
|
||||
becomes available. In order to autostart a mediated device, use the
|
||||
following command:
|
||||
</p>
|
||||
|
||||
<pre>$ virsh nodedev-autostart <device-name></pre>
|
||||
</body>
|
||||
</html>
|
||||
348
docs/drvnodedev.rst
Normal file
348
docs/drvnodedev.rst
Normal file
@ -0,0 +1,348 @@
|
||||
.. role:: since
|
||||
|
||||
======================
|
||||
Host device management
|
||||
======================
|
||||
|
||||
.. contents::
|
||||
|
||||
Libvirt provides management of both physical and virtual host devices
|
||||
(historically also referred to as node devices) like USB, PCI, SCSI, and network
|
||||
devices. This also includes various virtualization capabilities which the
|
||||
aforementioned devices provide for utilization, for example SR-IOV, NPIV, MDEV,
|
||||
DRM, etc.
|
||||
|
||||
The node device driver provides means to list and show details about host
|
||||
devices (``virsh nodedev-list``, ``virsh nodedev-info``, and
|
||||
``virsh nodedev-dumpxml``), which are generic and can be used with all devices.
|
||||
It also provides the means to manage virtual devices. Persistently-defined
|
||||
virtual devices are only supported for mediated devices, while transient devices
|
||||
are supported by both mediated devices and NPIV (`more info about
|
||||
NPIV) <https://wiki.libvirt.org/page/NPIV_in_libvirt>`__).
|
||||
|
||||
Persistent virtual devices are managed with ``virsh nodedev-define`` and
|
||||
``virsh nodedev-undefine``. Persistent devices can be configured to start
|
||||
manually or automatically using ``virsh nodedev-autostart``. Inactive devices
|
||||
can be made active with ``virsh nodedev-start``.
|
||||
|
||||
Transient virtual devices are started and stopped with the commands
|
||||
``virsh nodedev-create`` and ``virsh nodedev-destroy``.
|
||||
|
||||
Devices on the host system are arranged in a tree-like hierarchy, with the root
|
||||
node being called ``computer``. The node device driver supports udev backend
|
||||
(HAL backend was removed in ``6.8.0``).
|
||||
|
||||
Details of the XML format of a host device can be found
|
||||
`here <formatnode.html>`__. Of particular interest is the ``capability``
|
||||
element, which describes features supported by the device. Some specific device
|
||||
types are addressed in more detail below.
|
||||
|
||||
Basic structure of a node device
|
||||
--------------------------------
|
||||
|
||||
::
|
||||
|
||||
<device>
|
||||
<name>pci_0000_00_17_0</name>
|
||||
<path>/sys/devices/pci0000:00/0000:00:17.0</path>
|
||||
<parent>computer</parent>
|
||||
<driver>
|
||||
<name>ahci</name>
|
||||
</driver>
|
||||
<capability type='pci'>
|
||||
...
|
||||
</capability>
|
||||
</device>
|
||||
|
||||
PCI host devices
|
||||
----------------
|
||||
|
||||
``capability``
|
||||
When used as top level element, the supported values for the ``type``
|
||||
attribute are ``pci`` and ``phys_function`` (see `SR-IOV
|
||||
below <#SRIOVCap>`__).
|
||||
|
||||
::
|
||||
|
||||
<device>
|
||||
<name>pci_0000_04_00_1</name>
|
||||
<path>/sys/devices/pci0000:00/0000:00:06.0/0000:04:00.1</path>
|
||||
<parent>pci_0000_00_06_0</parent>
|
||||
<driver>
|
||||
<name>igb</name>
|
||||
</driver>
|
||||
<capability type='pci'>
|
||||
<domain>0</domain>
|
||||
<bus>4</bus>
|
||||
<slot>0</slot>
|
||||
<function>1</function>
|
||||
<product id='0x10c9'>82576 Gigabit Network Connection</product>
|
||||
<vendor id='0x8086'>Intel Corporation</vendor>
|
||||
<iommuGroup number='15'>
|
||||
<address domain='0x0000' bus='0x04' slot='0x00' function='0x1'/>
|
||||
</iommuGroup>
|
||||
<numa node='0'/>
|
||||
<pci-express>
|
||||
<link validity='cap' port='1' speed='2.5' width='2'/>
|
||||
<link validity='sta' speed='2.5' width='2'/>
|
||||
</pci-express>
|
||||
</capability>
|
||||
</device>
|
||||
|
||||
The XML format for a PCI device stays the same for any further capabilities it
|
||||
supports, a single nested ``<capability>`` element will be included for each
|
||||
capability the device supports.
|
||||
|
||||
SR-IOV capability
|
||||
~~~~~~~~~~~~~~~~~
|
||||
|
||||
Single root input/output virtualization (SR-IOV) allows sharing of the PCIe
|
||||
resources by multiple virtual environments. That is achieved by slicing up a
|
||||
single full-featured physical resource called physical function (PF) into
|
||||
multiple devices called virtual functions (VFs) sharing their configuration with
|
||||
the underlying PF. Despite the SR-IOV specification, the amount of VFs that can
|
||||
be created on a PF varies among manufacturers.
|
||||
|
||||
Suppose the NIC `above <#PCI>`__ was also SR-IOV capable, it would also include
|
||||
a nested ``<capability>`` element enumerating all virtual functions available on
|
||||
the physical device (physical port) like in the example below.
|
||||
|
||||
::
|
||||
|
||||
<capability type='pci'>
|
||||
...
|
||||
<capability type='virt_functions' maxCount='7'>
|
||||
<address domain='0x0000' bus='0x04' slot='0x10' function='0x1'/>
|
||||
<address domain='0x0000' bus='0x04' slot='0x10' function='0x3'/>
|
||||
<address domain='0x0000' bus='0x04' slot='0x10' function='0x5'/>
|
||||
<address domain='0x0000' bus='0x04' slot='0x10' function='0x7'/>
|
||||
<address domain='0x0000' bus='0x04' slot='0x11' function='0x1'/>
|
||||
<address domain='0x0000' bus='0x04' slot='0x11' function='0x3'/>
|
||||
<address domain='0x0000' bus='0x04' slot='0x11' function='0x5'/>
|
||||
</capability>
|
||||
...
|
||||
</capability>
|
||||
|
||||
A SR-IOV child device on the other hand, would then report its top level
|
||||
capability type as a ``phys_function`` instead:
|
||||
|
||||
::
|
||||
|
||||
<device>
|
||||
...
|
||||
<capability type='phys_function'>
|
||||
<address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
|
||||
</capability>
|
||||
...
|
||||
</device>
|
||||
|
||||
MDEV capability
|
||||
~~~~~~~~~~~~~~~
|
||||
|
||||
A device capable of creating mediated devices will include a nested capability
|
||||
``mdev_types`` which enumerates all supported mdev types on the physical device,
|
||||
along with the type attributes available through sysfs. A detailed description
|
||||
of the XML format for the ``mdev_types`` capability can be found
|
||||
`here <formatnode.html#MDEVTypesCap>`__.
|
||||
|
||||
The following example shows how we might represent an NVIDIA GPU device that
|
||||
supports mediated devices. See below for `more information about mediated
|
||||
devices <#MDEV>`__.
|
||||
|
||||
::
|
||||
|
||||
<device>
|
||||
...
|
||||
<driver>
|
||||
<name>nvidia</name>
|
||||
</driver>
|
||||
<capability type='pci'>
|
||||
...
|
||||
<capability type='mdev_types'>
|
||||
<type id='nvidia-11'>
|
||||
<name>GRID M60-0B</name>
|
||||
<deviceAPI>vfio-pci</deviceAPI>
|
||||
<availableInstances>16</availableInstances>
|
||||
</type>
|
||||
<!-- Here would come the rest of the available mdev types -->
|
||||
</capability>
|
||||
...
|
||||
</capability>
|
||||
</device>
|
||||
|
||||
VPD capability
|
||||
~~~~~~~~~~~~~~
|
||||
|
||||
A device that exposes a PCI/PCIe VPD capability will include a nested capability
|
||||
``vpd`` which presents data stored in the Vital Product Data (VPD). VPD provides
|
||||
a device name and a number of other standard-defined read-only fields (change
|
||||
level, manufacture id, part number, serial number) and vendor-specific read-only
|
||||
fields. Additionally, if a device supports it, read-write fields (asset tag,
|
||||
vendor-specific fields or system fields) may also be present. The VPD capability
|
||||
is optional for PCI/PCIe devices and the set of exposed fields may vary
|
||||
depending on a device. The XML format follows the binary format described in
|
||||
"I.3. VPD Definitions" in PCI Local Bus (2.2+) and the identical format in PCIe
|
||||
4.0+. At the time of writing, the support for exposing this capability is only
|
||||
present on Linux-based systems (kernel version v2.6.26 is the first one to
|
||||
expose VPD via sysfs which Libvirt relies on). Reading the VPD contents requires
|
||||
root privileges, therefore, ``virsh nodedev-dumpxml`` must be executed
|
||||
accordingly. A description of the XML format for the ``vpd`` capability can be
|
||||
found `here <formatnode.html#VPDCap>`__.
|
||||
|
||||
The following example shows a VPD representation for a device that exposes the
|
||||
VPD capability with read-only and read-write fields. Among other things, the VPD
|
||||
of this particular device includes a unique board serial number.
|
||||
|
||||
::
|
||||
|
||||
<device>
|
||||
<name>pci_0000_42_00_0</name>
|
||||
<capability type='pci'>
|
||||
<class>0x020000</class>
|
||||
<domain>0</domain>
|
||||
<bus>66</bus>
|
||||
<slot>0</slot>
|
||||
<function>0</function>
|
||||
<product id='0xa2d6'>MT42822 BlueField-2 integrated ConnectX-6 Dx network controller</product>
|
||||
<vendor id='0x15b3'>Mellanox Technologies</vendor>
|
||||
<capability type='virt_functions' maxCount='16'/>
|
||||
<capability type='vpd'>
|
||||
<name>BlueField-2 DPU 25GbE Dual-Port SFP56, Crypto Enabled, 16GB on-board DDR, 1GbE OOB management, Tall Bracket</name>
|
||||
<fields access='readonly'>
|
||||
<change_level>B1</change_level>
|
||||
<manufacture_id>foobar</manufacture_id>
|
||||
<part_number>MBF2H332A-AEEOT</part_number>
|
||||
<serial_number>MT2113X00000</serial_number>
|
||||
<vendor_field index='0'>PCIeGen4 x8</vendor_field>
|
||||
<vendor_field index='2'>MBF2H332A-AEEOT</vendor_field>
|
||||
<vendor_field index='3'>3c53d07eec484d8aab34dabd24fe575aa</vendor_field>
|
||||
<vendor_field index='A'>MLX:MN=MLNX:CSKU=V2:UUID=V3:PCI=V0:MODL=BF2H332A</vendor_field>
|
||||
</fields>
|
||||
<fields access='readwrite'>
|
||||
<asset_tag>fooasset</asset_tag>
|
||||
<vendor_field index='0'>vendorfield0</vendor_field>
|
||||
<vendor_field index='2'>vendorfield2</vendor_field>
|
||||
<vendor_field index='A'>vendorfieldA</vendor_field>
|
||||
<system_field index='B'>systemfieldB</system_field>
|
||||
<system_field index='0'>systemfield0</system_field>
|
||||
</fields>
|
||||
</capability>
|
||||
<iommuGroup number='65'>
|
||||
<address domain='0x0000' bus='0x42' slot='0x00' function='0x0'/>
|
||||
</iommuGroup>
|
||||
<numa node='0'/>
|
||||
<pci-express>
|
||||
<link validity='cap' port='0' speed='16' width='8'/>
|
||||
<link validity='sta' speed='8' width='8'/>
|
||||
</pci-express>
|
||||
</capability>
|
||||
</device>
|
||||
|
||||
Mediated devices (MDEVs)
|
||||
------------------------
|
||||
|
||||
Mediated devices ( :since:`Since 3.2.0` ) are software devices defining resource
|
||||
allocation on the backing physical device which in turn allows the parent
|
||||
physical device's resources to be divided into several mediated devices, thus
|
||||
sharing the physical device's performance among multiple guests. Unlike SR-IOV
|
||||
however, where a PCIe device appears as multiple separate PCIe devices on the
|
||||
host's PCI bus, mediated devices only appear on the mdev virtual bus. Therefore,
|
||||
no detach/reattach procedure from/to the host driver procedure is involved even
|
||||
though mediated devices are used in a direct device assignment manner. A
|
||||
detailed description of the XML format for the ``mdev`` capability can be found
|
||||
`here <formatnode.html#mdev>`__.
|
||||
|
||||
Example of a mediated device
|
||||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
::
|
||||
|
||||
<device>
|
||||
<name>mdev_4b20d080_1b54_4048_85b3_a6a62d165c01</name>
|
||||
<path>/sys/devices/pci0000:00/0000:00:02.0/4b20d080-1b54-4048-85b3-a6a62d165c01</path>
|
||||
<parent>pci_0000_06_00_0</parent>
|
||||
<driver>
|
||||
<name>vfio_mdev</name>
|
||||
</driver>
|
||||
<capability type='mdev'>
|
||||
<type id='nvidia-11'/>
|
||||
<uuid>4b20d080-1b54-4048-85b3-a6a62d165c01</uuid>
|
||||
<iommuGroup number='12'/>
|
||||
</capability>
|
||||
</device>
|
||||
|
||||
The support of mediated device's framework in libvirt's node device driver
|
||||
covers the following features:
|
||||
|
||||
- list available mediated devices on the host ( :since:`Since 3.4.0` )
|
||||
- display device details ( :since:`Since 3.4.0` )
|
||||
- create transient mediated devices ( :since:`Since 6.5.0` )
|
||||
- define persistent mediated devices ( :since:`Since 7.3.0` )
|
||||
|
||||
Because mediated devices are instantiated from vendor specific templates, simply
|
||||
called 'types', information describing these types is contained within the
|
||||
parent device's capabilities (see the example in `PCI host devices <#PCI>`__).
|
||||
To list all devices capable of creating mediated devices, the following command
|
||||
can be used.
|
||||
|
||||
::
|
||||
|
||||
$ virsh nodedev-list --cap mdev_types
|
||||
|
||||
To see the supported mediated device types on a specific physical device use the
|
||||
following:
|
||||
|
||||
::
|
||||
|
||||
$ virsh nodedev-dumpxml <device>
|
||||
|
||||
Before creating a mediated device, unbind the device from the respective device
|
||||
driver, eg. subchannel I/O driver for a CCW device. Then bind the device to the
|
||||
respective VFIO driver. For a CCW device, also unbind the corresponding
|
||||
subchannel of the CCW device from the subchannel I/O driver and then bind the
|
||||
subchannel (instead of the CCW device) to the vfio_ccw driver. The below example
|
||||
shows the unbinding and binding steps for a CCW device.
|
||||
|
||||
::
|
||||
|
||||
device="0.0.1234"
|
||||
subchannel="0.0.0123"
|
||||
echo $device > /sys/bus/ccw/devices/$device/driver/unbind
|
||||
echo $subchannel > /sys/bus/css/devices/$subchannel/driver/unbind
|
||||
echo $subchannel > /sys/bus/css/drivers/vfio_ccw/bind
|
||||
|
||||
To instantiate a transient mediated device, create an XML file representing the
|
||||
device. See above for information about the mediated device xml format.
|
||||
|
||||
::
|
||||
|
||||
$ virsh nodedev-create <xml-file>
|
||||
Node device '<device-name>' created from '<xml-file>'
|
||||
|
||||
If you would like to persistently define the device so that it will be
|
||||
maintained across host reboots, use ``virsh nodedev-define`` instead of
|
||||
``nodedev-create``:
|
||||
|
||||
::
|
||||
|
||||
$ virsh nodedev-define <xml-file>
|
||||
Node device '<device-name>' defined from '<xml-file>'
|
||||
|
||||
To start an instance of this device definition, use the following command:
|
||||
|
||||
::
|
||||
|
||||
$ virsh nodedev-start <device-name>
|
||||
|
||||
Active mediated device instances can be stopped using
|
||||
``virsh nodedev-destroy``, and persistent device definitions can be
|
||||
removed using ``virsh nodedev-undefine``.
|
||||
|
||||
If a mediated device is defined persistently, it can also be set to be
|
||||
automatically started whenever the host reboots or when the parent device
|
||||
becomes available. In order to autostart a mediated device, use the following
|
||||
command:
|
||||
|
||||
::
|
||||
|
||||
$ virsh nodedev-autostart <device-name>
|
||||
@ -4166,7 +4166,8 @@ or:
|
||||
specifies the device API which determines how the host's vfio driver will
|
||||
expose the device to the guest. Currently, ``model='vfio-pci'``,
|
||||
``model='vfio-ccw'`` ( :since:`Since 4.4.0` ) and ``model='vfio-ap'`` (
|
||||
:since:`Since 4.9.0` ) is supported. `MDEV <drvnodedev.html#MDEV>`__
|
||||
:since:`Since 4.9.0` ) is supported.
|
||||
`MDEV <drvnodedev.html#mediated-devices-mdevs>`__
|
||||
section provides more information about mediated devices as well as how to
|
||||
create mediated devices on the host. :since:`Since 4.6.0 (QEMU 2.12)` an
|
||||
optional ``display`` attribute may be used to enable or disable support
|
||||
|
||||
@ -22,7 +22,6 @@ docs_html_in_files = [
|
||||
'csharp',
|
||||
'dbus',
|
||||
'docs',
|
||||
'drvnodedev',
|
||||
'drvopenvz',
|
||||
'drvsecret',
|
||||
'drvtest',
|
||||
@ -80,6 +79,7 @@ docs_rst_files = [
|
||||
'drvesx',
|
||||
'drvhyperv',
|
||||
'drvlxc',
|
||||
'drvnodedev',
|
||||
'drvqemu',
|
||||
'errors',
|
||||
'formatbackup',
|
||||
|
||||
Loading…
Reference in New Issue
Block a user