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docs: Add documentation for SR-IOV and Virtualization Enhancements 

Documentation describes 5 new parameters being added regarding SR-IOV:
sriov_max_vfs
sriov_vq_flexible
sriov_vi_flexible
sriov_max_vi_per_vf
sriov_max_vq_per_vf

The description also includes the simplest possible QEMU invocation
and the series of NVMe commands required to enable SR-IOV support.

Signed-off-by: Lukasz Maniak <lukasz.maniak@linux.intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
This commit is contained in:
Lukasz Maniak 2022-05-09 16:16:18 +02:00 committed by Klaus Jensen
parent 11871f53ef
commit 751babf5bb
1 changed files with 82 additions and 0 deletions
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docs/system/devices/nvme.rst
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@ -239,3 +239,85 @@ The virtual namespace device supports DIF- and DIX-based protection information
to ``1`` to transfer protection information as the first eight bytes of
metadata. Otherwise, the protection information is transferred as the last
eight bytes.
Virtualization Enhancements and SR-IOV (Experimental Support)
-------------------------------------------------------------
The ``nvme`` device supports Single Root I/O Virtualization and Sharing
along with Virtualization Enhancements. The controller has to be linked to
an NVM Subsystem device (``nvme-subsys``) for use with SR-IOV.
A number of parameters are present (**please note, that they may be
subject to change**):
``sriov_max_vfs`` (default: ``0``)
Indicates the maximum number of PCIe virtual functions supported
by the controller. Specifying a non-zero value enables reporting of both
SR-IOV and ARI (Alternative Routing-ID Interpretation) capabilities
by the NVMe device. Virtual function controllers will not report SR-IOV.
``sriov_vq_flexible``
Indicates the total number of flexible queue resources assignable to all
the secondary controllers. Implicitly sets the number of primary
controller's private resources to ``(max_ioqpairs - sriov_vq_flexible)``.
``sriov_vi_flexible``
Indicates the total number of flexible interrupt resources assignable to
all the secondary controllers. Implicitly sets the number of primary
controller's private resources to ``(msix_qsize - sriov_vi_flexible)``.
``sriov_max_vi_per_vf`` (default: ``0``)
Indicates the maximum number of virtual interrupt resources assignable
to a secondary controller. The default ``0`` resolves to
``(sriov_vi_flexible / sriov_max_vfs)``
``sriov_max_vq_per_vf`` (default: ``0``)
Indicates the maximum number of virtual queue resources assignable to
a secondary controller. The default ``0`` resolves to
``(sriov_vq_flexible / sriov_max_vfs)``
The simplest possible invocation enables the capability to set up one VF
controller and assign an admin queue, an IO queue, and a MSI-X interrupt.
.. code-block:: console
-device nvme-subsys,id=subsys0
-device nvme,serial=deadbeef,subsys=subsys0,sriov_max_vfs=1,
sriov_vq_flexible=2,sriov_vi_flexible=1
The minimum steps required to configure a functional NVMe secondary
controller are:
* unbind flexible resources from the primary controller
.. code-block:: console
nvme virt-mgmt /dev/nvme0 -c 0 -r 1 -a 1 -n 0
nvme virt-mgmt /dev/nvme0 -c 0 -r 0 -a 1 -n 0
* perform a Function Level Reset on the primary controller to actually
release the resources
.. code-block:: console
echo 1 > /sys/bus/pci/devices/0000:01:00.0/reset
* enable VF
.. code-block:: console
echo 1 > /sys/bus/pci/devices/0000:01:00.0/sriov_numvfs
* assign the flexible resources to the VF and set it ONLINE
.. code-block:: console
nvme virt-mgmt /dev/nvme0 -c 1 -r 1 -a 8 -n 1
nvme virt-mgmt /dev/nvme0 -c 1 -r 0 -a 8 -n 2
nvme virt-mgmt /dev/nvme0 -c 1 -r 0 -a 9 -n 0
* bind the NVMe driver to the VF
.. code-block:: console
echo 0000:01:00.1 > /sys/bus/pci/drivers/nvme/bind