[[qm_pci_passthrough]]
PCI(e) Passthrough
------------------
+ifdef::wiki[]
+:pve-toplevel:
+endif::wiki[]
PCI(e) passthrough is a mechanism to give a virtual machine control over
a PCI device from the host. This can have some advantages over using
enabled.
----
-# dmesg -e DMAR -e IOMMU -e AMD-Vi
+# dmesg | grep -e DMAR -e IOMMU -e AMD-Vi
----
should display that `IOMMU`, `Directed I/O` or `Interrupt Remapping` is
Please be aware that this option can make your system unstable.
====
+GPU Passthrough Notes
+^^^^^^^^^^^^^^^^^^^^^
+
+It is not possible to display the frame buffer of the GPU via NoVNC or SPICE on
+the {pve} web interface.
+
+When passing through a whole GPU or a vGPU and graphic output is wanted, one
+has to either physically connect a monitor to the card, or configure a remote
+desktop software (for example, VNC or RDP) inside the guest.
+
+If you want to use the GPU as a hardware accelerator, for example, for
+programs using OpenCL or CUDA, this is not required.
+
Host Device Passthrough
~~~~~~~~~~~~~~~~~~~~~~~
# qm set VMID -hostpci0 00:02.0
----
-If your device has multiple functions, you can pass them through all together
-with the shortened syntax ``00:02`'
+If your device has multiple functions (e.g., ``00:02.0`' and ``00:02.1`' ),
+you can pass them through all together with the shortened syntax ``00:02`'
There are some options to which may be necessary, depending on the device
and guest OS:
for it to work. In doubt, consult the manual of the platform or contact its
vendor.
-Mediated Devices, vGPU/GVT-g
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Mediated Devices (vGPU, GVT-g)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Mediated devices are another method to use reuse features and performance from
+physical hardware for virtualized hardware. These are found most common in
+virtualized GPU setups such as Intels GVT-g and Nvidias vGPUs used in their
+GRID technology.
-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.
-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
+In general your card's driver 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.
+with the 5th, 6th and 7th generation Intel Core Processors, further E3 v4, E3
+v5 and E3 v6 Xeon Processors are supported.
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:
+commandline. For this you can edit `'/etc/default/grub'' and add the following
+to the 'GRUB_CMDLINE_LINUX_DEFAULT' variable:
----
i915.enable_gvt=1
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.
+To use a mediated device, simply specify the `mdev` property on a `hostpciX`
+VM configuration option.
-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:
+You can get the supported devices via the 'sysfs'. For example, to list the
+supported types for the device '0000:00:02.0' you would simply execute:
----
# 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
+* 'available_instances' contains the amount of still available instances of
+this type, each 'mdev' use in a VM reduces this.
* '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.
+* 'create' is the endpoint to create such a device, {pve} does this
+automatically for you, if a 'hostpciX' option with `mdev` is configured.
-Example configuration of a Intel GVT-g vGPU on an Intel Skylake 6700k Processor:
+Example configuration with an `Intel GVT-g vGPU` (`Intel Skylake 6700k`):
----
# 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.
+
+ifdef::wiki[]
+
+See Also
+~~~~~~~~
+
+* link:/wiki/Pci_passthrough[PCI Passthrough Examples]
+
+endif::wiki[]
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