226 lines
7.6 KiB
ReStructuredText
226 lines
7.6 KiB
ReStructuredText
==============
|
|
NVMe Emulation
|
|
==============
|
|
|
|
QEMU provides NVMe emulation through the ``nvme``, ``nvme-ns`` and
|
|
``nvme-subsys`` devices.
|
|
|
|
See the following sections for specific information on
|
|
|
|
* `Adding NVMe Devices`_, `additional namespaces`_ and `NVM subsystems`_.
|
|
* Configuration of `Optional Features`_ such as `Controller Memory Buffer`_,
|
|
`Simple Copy`_, `Zoned Namespaces`_, `metadata`_ and `End-to-End Data
|
|
Protection`_,
|
|
|
|
Adding NVMe Devices
|
|
===================
|
|
|
|
Controller Emulation
|
|
--------------------
|
|
|
|
The QEMU emulated NVMe controller implements version 1.4 of the NVM Express
|
|
specification. All mandatory features are implement with a couple of exceptions
|
|
and limitations:
|
|
|
|
* Accounting numbers in the SMART/Health log page are reset when the device
|
|
is power cycled.
|
|
* Interrupt Coalescing is not supported and is disabled by default.
|
|
|
|
The simplest way to attach an NVMe controller on the QEMU PCI bus is to add the
|
|
following parameters:
|
|
|
|
.. code-block:: console
|
|
|
|
-drive file=nvm.img,if=none,id=nvm
|
|
-device nvme,serial=deadbeef,drive=nvm
|
|
|
|
There are a number of optional general parameters for the ``nvme`` device. Some
|
|
are mentioned here, but see ``-device nvme,help`` to list all possible
|
|
parameters.
|
|
|
|
``max_ioqpairs=UINT32`` (default: ``64``)
|
|
Set the maximum number of allowed I/O queue pairs. This replaces the
|
|
deprecated ``num_queues`` parameter.
|
|
|
|
``msix_qsize=UINT16`` (default: ``65``)
|
|
The number of MSI-X vectors that the device should support.
|
|
|
|
``mdts=UINT8`` (default: ``7``)
|
|
Set the Maximum Data Transfer Size of the device.
|
|
|
|
``use-intel-id`` (default: ``off``)
|
|
Since QEMU 5.2, the device uses a QEMU allocated "Red Hat" PCI Device and
|
|
Vendor ID. Set this to ``on`` to revert to the unallocated Intel ID
|
|
previously used.
|
|
|
|
Additional Namespaces
|
|
---------------------
|
|
|
|
In the simplest possible invocation sketched above, the device only support a
|
|
single namespace with the namespace identifier ``1``. To support multiple
|
|
namespaces and additional features, the ``nvme-ns`` device must be used.
|
|
|
|
.. code-block:: console
|
|
|
|
-device nvme,id=nvme-ctrl-0,serial=deadbeef
|
|
-drive file=nvm-1.img,if=none,id=nvm-1
|
|
-device nvme-ns,drive=nvm-1
|
|
-drive file=nvm-2.img,if=none,id=nvm-2
|
|
-device nvme-ns,drive=nvm-2
|
|
|
|
The namespaces defined by the ``nvme-ns`` device will attach to the most
|
|
recently defined ``nvme-bus`` that is created by the ``nvme`` device. Namespace
|
|
identifers are allocated automatically, starting from ``1``.
|
|
|
|
There are a number of parameters available:
|
|
|
|
``nsid`` (default: ``0``)
|
|
Explicitly set the namespace identifier.
|
|
|
|
``uuid`` (default: *autogenerated*)
|
|
Set the UUID of the namespace. This will be reported as a "Namespace UUID"
|
|
descriptor in the Namespace Identification Descriptor List.
|
|
|
|
``bus``
|
|
If there are more ``nvme`` devices defined, this parameter may be used to
|
|
attach the namespace to a specific ``nvme`` device (identified by an ``id``
|
|
parameter on the controller device).
|
|
|
|
NVM Subsystems
|
|
--------------
|
|
|
|
Additional features becomes available if the controller device (``nvme``) is
|
|
linked to an NVM Subsystem device (``nvme-subsys``).
|
|
|
|
The NVM Subsystem emulation allows features such as shared namespaces and
|
|
multipath I/O.
|
|
|
|
.. code-block:: console
|
|
|
|
-device nvme-subsys,id=nvme-subsys-0,nqn=subsys0
|
|
-device nvme,serial=a,subsys=nvme-subsys-0
|
|
-device nvme,serial=b,subsys=nvme-subsys-0
|
|
|
|
This will create an NVM subsystem with two controllers. Having controllers
|
|
linked to an ``nvme-subsys`` device allows additional ``nvme-ns`` parameters:
|
|
|
|
``shared`` (default: ``off``)
|
|
Specifies that the namespace will be attached to all controllers in the
|
|
subsystem. If set to ``off`` (the default), the namespace will remain a
|
|
private namespace and may only be attached to a single controller at a time.
|
|
|
|
``detached`` (default: ``off``)
|
|
If set to ``on``, the namespace will be be available in the subsystem, but
|
|
not attached to any controllers initially.
|
|
|
|
Thus, adding
|
|
|
|
.. code-block:: console
|
|
|
|
-drive file=nvm-1.img,if=none,id=nvm-1
|
|
-device nvme-ns,drive=nvm-1,nsid=1,shared=on
|
|
-drive file=nvm-2.img,if=none,id=nvm-2
|
|
-device nvme-ns,drive=nvm-2,nsid=3,detached=on
|
|
|
|
will cause NSID 1 will be a shared namespace (due to ``shared=on``) that is
|
|
initially attached to both controllers. NSID 3 will be a private namespace
|
|
(i.e. only attachable to a single controller at a time) and will not be
|
|
attached to any controller initially (due to ``detached=on``).
|
|
|
|
Optional Features
|
|
=================
|
|
|
|
Controller Memory Buffer
|
|
------------------------
|
|
|
|
``nvme`` device parameters related to the Controller Memory Buffer support:
|
|
|
|
``cmb_size_mb=UINT32`` (default: ``0``)
|
|
This adds a Controller Memory Buffer of the given size at offset zero in BAR
|
|
2.
|
|
|
|
``legacy-cmb`` (default: ``off``)
|
|
By default, the device uses the "v1.4 scheme" for the Controller Memory
|
|
Buffer support (i.e, the CMB is initially disabled and must be explicitly
|
|
enabled by the host). Set this to ``on`` to behave as a v1.3 device wrt. the
|
|
CMB.
|
|
|
|
Simple Copy
|
|
-----------
|
|
|
|
The device includes support for TP 4065 ("Simple Copy Command"). A number of
|
|
additional ``nvme-ns`` device parameters may be used to control the Copy
|
|
command limits:
|
|
|
|
``mssrl=UINT16`` (default: ``128``)
|
|
Set the Maximum Single Source Range Length (``MSSRL``). This is the maximum
|
|
number of logical blocks that may be specified in each source range.
|
|
|
|
``mcl=UINT32`` (default: ``128``)
|
|
Set the Maximum Copy Length (``MCL``). This is the maximum number of logical
|
|
blocks that may be specified in a Copy command (the total for all source
|
|
ranges).
|
|
|
|
``msrc=UINT8`` (default: ``127``)
|
|
Set the Maximum Source Range Count (``MSRC``). This is the maximum number of
|
|
source ranges that may be used in a Copy command. This is a 0's based value.
|
|
|
|
Zoned Namespaces
|
|
----------------
|
|
|
|
A namespaces may be "Zoned" as defined by TP 4053 ("Zoned Namespaces"). Set
|
|
``zoned=on`` on an ``nvme-ns`` device to configure it as a zoned namespace.
|
|
|
|
The namespace may be configured with additional parameters
|
|
|
|
``zoned.zone_size=SIZE`` (default: ``128MiB``)
|
|
Define the zone size (``ZSZE``).
|
|
|
|
``zoned.zone_capacity=SIZE`` (default: ``0``)
|
|
Define the zone capacity (``ZCAP``). If left at the default (``0``), the zone
|
|
capacity will equal the zone size.
|
|
|
|
``zoned.descr_ext_size=UINT32`` (default: ``0``)
|
|
Set the Zone Descriptor Extension Size (``ZDES``). Must be a multiple of 64
|
|
bytes.
|
|
|
|
``zoned.cross_read=BOOL`` (default: ``off``)
|
|
Set to ``on`` to allow reads to cross zone boundaries.
|
|
|
|
``zoned.max_active=UINT32`` (default: ``0``)
|
|
Set the maximum number of active resources (``MAR``). The default (``0``)
|
|
allows all zones to be active.
|
|
|
|
``zoned.max_open=UINT32`` (default: ``0``)
|
|
Set the maximum number of open resources (``MOR``). The default (``0``)
|
|
allows all zones to be open. If ``zoned.max_active`` is specified, this value
|
|
must be less than or equal to that.
|
|
|
|
Metadata
|
|
--------
|
|
|
|
The virtual namespace device supports LBA metadata in the form separate
|
|
metadata (``MPTR``-based) and extended LBAs.
|
|
|
|
``ms=UINT16`` (default: ``0``)
|
|
Defines the number of metadata bytes per LBA.
|
|
|
|
``mset=UINT8`` (default: ``0``)
|
|
Set to ``1`` to enable extended LBAs.
|
|
|
|
End-to-End Data Protection
|
|
--------------------------
|
|
|
|
The virtual namespace device supports DIF- and DIX-based protection information
|
|
(depending on ``mset``).
|
|
|
|
``pi=UINT8`` (default: ``0``)
|
|
Enable protection information of the specified type (type ``1``, ``2`` or
|
|
``3``).
|
|
|
|
``pil=UINT8`` (default: ``0``)
|
|
Controls the location of the protection information within the metadata. Set
|
|
to ``1`` to transfer protection information as the first eight bytes of
|
|
metadata. Otherwise, the protection information is transferred as the last
|
|
eight bytes.
|