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add documentation for mediated devices

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Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
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Dominik Csapak 2018-11-13 15:18:14 +01:00 committed by Thomas Lamprecht
parent 39d84f286a
commit 050192c59d
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qm-pci-passthrough.adoc
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@ -275,3 +275,71 @@ For this feature, platform support is especially important. It may be necessary
to enable this feature in the BIOS/EFI first, or to use a specific PCI(e) port
for it to work. In doubt, consult the manual of the platform or contact its
vendor.
Mediated Devices, vGPU/GVT-g
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mediated devices are another method to use virtualized hardware.
These are found most common in virtualized GPU setups such as
Intels GVT-g and Nvidias vGPUs used in their GRID technology.
With this, a physical Card is able to create virtual cards, similar to
SR-IOV, the difference is that mediated devices do not appear as PCI(e) devices
in the host, and are such only suited for using in virtual machines.
Host Configuration
^^^^^^^^^^^^^^^^^^
In general your driver of the card must support that feature, otherwise it will
not work. So please refer to your vendor for compatbile drivers and how to
configure them.
Intels drivers for GVT-g are integraded in the Kernel and should work
with 5th, 6th and 7th generation Intel Core Processors and E3 v4, E3 v5 and
E3 v6 Xeon Processors.
To enable it for Intel Graphcs, you have to make sure to load the module
'kvmgt' (for example via `/etc/modules`) and to enable it on the Kernel
commandline. For this you can edit `'/etc/default/grub''
and add the following to the 'GRUB_CMDLINE_LINUX_DEFAULT' variable:
----
i915.enable_gvt=1
----
After that remember to
xref:qm_pci_passthrough_update_initramfs[update the `initramfs`],
xref:qm_pci_passthrough_update_grub[update grub] and
reboot your host.
VM Configuration
^^^^^^^^^^^^^^^^
To use a mediated device, simply specify the `mdev` on a `hostpciX`
configuration of a VM. This needs to be a type of mediated device supported
by the specified PCI(e) card.
You can get the supported devices via the 'sysfs'. For example, listing
the supported types for the device '0000:00:02.0' you can simply list them
with:
----
# ls /sys/bus/pci/devices/0000:00:02.0/mdev_supported_types
----
Each entry is a directory which contains the following important files:
* 'available_instances' contains the amount of still available instances of this
type
* 'description' contains a short description about the capabilities of the type
* 'create' is the endpoint to create such a device, in {pve} this happens
automatically if you specify a type with a 'hostpciX' line.
Example configuration of a Intel GVT-g vGPU on an Intel Skylake 6700k Processor:
----
# qm set VMID -hostpci0 00:02.0,mdev=i915-GVTg_V5_4
----
With this set, {pve} automatically creates such a device on VM start, and
cleans it up again when the VM stops.