docs: Rework the PCI passthrough guides
Rewrite the document, making the following changes: - Remove use of bullet points in favour of more descriptive steps - Cross-reference various configuration options - Emphasise that ``[pci] alias`` must be set on both controller and compute node - Style nits, such as fixing the header style Change-Id: I2ac7df7d235f0af25f5a99bc8f6abddbae2cb3af Signed-off-by: Stephen Finucane <sfinucan@redhat.com>
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Stephen Finucane
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@ -22,48 +22,51 @@ assigned to only one guest and cannot be shared.
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**Limitations**
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* Attaching SR-IOV ports to existing servers is not currently supported, see
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`bug 1708433 <https://bugs.launchpad.net/nova/+bug/1708433>`_ for details.
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* Attaching SR-IOV ports to existing servers is not currently supported.
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This is now rejected by the API but previously it fail later in the
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process. See `bug 1708433 <https://bugs.launchpad.net/nova/+bug/1708433>`_
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for details.
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* Cold migration (resize) of servers with SR-IOV devices attached was not
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supported until the 14.0.0 Newton release, see
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`bug 1512800 <https://bugs.launchpad.net/nova/+bug/1512880>`_ for details.
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To enable PCI passthrough, follow the steps below:
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#. Configure nova-scheduler (Controller)
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#. Configure nova-api (Controller)**
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#. Configure a flavor (Controller)
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#. Enable PCI passthrough (Compute)
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#. Configure PCI devices in nova-compute (Compute)
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To enable PCI passthrough, follow the steps below.
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.. note::
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The PCI device with address ``0000:41:00.0`` is used as an example. This
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will differ between environments.
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The PCI device with address ``0000:41:00.0``, the vendor ID of ``8086`` and
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the product ID of ``154d`` is used as an example. This will differ between
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environments.
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Configure nova-scheduler (Controller)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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#. Configure ``nova-scheduler`` as specified in :neutron-doc:`Configure
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nova-scheduler
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<admin/config-sriov.html#configure-nova-scheduler-controller>`.
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Configure ``nova-scheduler`` (Controller)
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-----------------------------------------
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#. Restart the ``nova-scheduler`` service.
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The :program:`nova-scheduler` service must be configured to enable the
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``PciPassthroughFilter``. To do this, add this filter to the list of filters
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specified in :oslo.config:option:`filter_scheduler.enabled_filters` and set
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:oslo.config:option:`filter_scheduler.available_filters` to the default of
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``nova.scheduler.filters.all_filters``. For example:
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Configure nova-api (Controller)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. code-block:: ini
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#. Specify the PCI alias for the device.
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[filter_scheduler]
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enabled_filters = ...,PciPassthroughFilter
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available_filters = nova.scheduler.filters.all_filters
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Configure a PCI alias ``a1`` to request a PCI device with a ``vendor_id`` of
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``0x8086`` and a ``product_id`` of ``0x154d``. The ``vendor_id`` and
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``product_id`` correspond the PCI device with address ``0000:41:00.0``.
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Once done, restart the :program:`nova-scheduler` service.
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Edit ``/etc/nova/nova.conf``:
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.. _pci-passthrough-alias:
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Configure ``nova-api`` (Controller)
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-----------------------------------
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PCI devices are requested through flavor extra specs, specifically via the
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``pci_passthrough:alias`` flavor extra spec. However, the aliases themselves
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must be configured. This done via the :oslo.config:option:`pci.alias`
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configuration option. For example, to configure a PCI alias ``a1`` to request
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a PCI device with a vendor ID of ``0x8086`` and a product ID of ``0x154d``:
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.. code-block:: ini
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@ -72,33 +75,45 @@ Configure nova-api (Controller)
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Refer to :oslo.config:option:`pci.alias` for syntax information.
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#. Restart the ``nova-api`` service.
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Once configured, restart the :program:`nova-api` service.
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Configure a flavor (Controller)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. important::
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Configure a flavor to request two PCI devices, each with ``vendor_id`` of
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``0x8086`` and ``product_id`` of ``0x154d``:
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This option must also be configured on compute nodes. This is discussed later
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in this document.
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Configure a flavor (API)
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------------------------
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Once the alias has been configured, it can be used for an flavor extra spec.
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For example, to request two of the PCI devices referenced by alias ``a1``, run:
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.. code-block:: console
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# openstack flavor set m1.large --property "pci_passthrough:alias"="a1:2"
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$ openstack flavor set m1.large --property "pci_passthrough:alias"="a1:2"
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For more information about the syntax for ``pci_passthrough:alias``, refer to
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:ref:`Flavors <extra-spec-pci-passthrough>`.
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Enable PCI passthrough (Compute)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Enable VT-d and IOMMU. For more information, refer to steps one and two in
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:neutron-doc:`Create Virtual Functions
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<admin/config-sriov.html#create-virtual-functions-compute>`.
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Configure host (Compute)
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------------------------
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For Hyper-V compute nodes, the requirements are as follows:
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To enable PCI passthrough on an x86, Linux-based compute node, the following
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are required:
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* Windows 10 or Windows / Hyper-V Server 2016 or newer.
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* VT-d and SR-IOV enabled on the host.
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* Assignable PCI devices.
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* VT-d enabled in the BIOS
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* IOMMU enabled on the host OS, by adding the ``intel_iommu=on`` or
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``amd_iommu=on`` parameter to the kernel parameters
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* Assignable PCIe devices
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To enable PCI passthrough on a Hyper-V compute node, the following are
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required:
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* Windows 10 or Windows / Hyper-V Server 2016 or newer
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* VT-d enabled on the host
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* Assignable PCI devices
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In order to check the requirements above and if there are any assignable PCI
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devices, run the following Powershell commands:
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@ -115,40 +130,38 @@ passthrough`__.
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.. __: https://devblogs.microsoft.com/scripting/passing-through-devices-to-hyper-v-vms-by-using-discrete-device-assignment/
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Configure PCI devices (Compute)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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#. Configure ``nova-compute`` to allow the PCI device to pass through to
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VMs. Edit ``/etc/nova/nova.conf``:
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Configure ``nova-compute`` (Compute)
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------------------------------------
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Once PCI passthrough has been configured for the host, :program:`nova-compute`
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must be configured to allow the PCI device to pass through to VMs. This is done
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using the :oslo.config:option:`pci.passthrough_whitelist` option. For example,
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to enable passthrough of a specific device using its address:
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.. code-block:: ini
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[pci]
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passthrough_whitelist = { "address": "0000:41:00.0" }
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Alternatively specify multiple PCI devices using whitelisting:
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Refer to :oslo.config:option:`pci.passthrough_whitelist` for syntax information.
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Alternatively, to enable passthrough of all devices with the same product and
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vendor ID:
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.. code-block:: ini
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[pci]
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passthrough_whitelist = { "vendor_id": "8086", "product_id": "10fb" }
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passthrough_whitelist = { "vendor_id": "8086", "product_id": "154d" }
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All PCI devices matching the ``vendor_id`` and ``product_id`` are added to
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the pool of PCI devices available for passthrough to VMs.
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If using vendor and product IDs, all PCI devices matching the ``vendor_id`` and
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``product_id`` are added to the pool of PCI devices available for passthrough
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to VMs.
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Refer to :oslo.config:option:`pci.passthrough_whitelist` for syntax
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information.
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#. Specify the PCI alias for the device.
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From the Newton release, to resize guest with PCI device, configure the PCI
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alias on the compute node as well.
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Configure a PCI alias ``a1`` to request a PCI device with a ``vendor_id`` of
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``0x8086`` and a ``product_id`` of ``0x154d``. The ``vendor_id`` and
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``product_id`` correspond the PCI device with address ``0000:41:00.0``.
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Edit ``/etc/nova/nova.conf``:
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In addition, it is necessary to configure the :oslo.config:option:`pci.alias`
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option on the compute node too. This is required to allow resizes of guests
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with PCI devices. This should be identical to the alias configured
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:ref:`previously <pci-passthrough-alias>`. For example:
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.. code-block:: ini
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@ -157,14 +170,14 @@ Configure PCI devices (Compute)
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Refer to :oslo.config:option:`pci.alias` for syntax information.
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#. Restart the ``nova-compute`` service.
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Once configured, restart the :program:`nova-compute` service.
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Create instances with PCI passthrough devices
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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---------------------------------------------
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The ``nova-scheduler`` selects a destination host that has PCI devices
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available with the specified ``vendor_id`` and ``product_id`` that matches the
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``alias`` from the flavor.
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The :program:`nova-scheduler` service selects a destination host that has PCI
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devices available that match the ``alias`` specified in the flavor.
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.. code-block:: console
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