Import QEMU upstream snapshot d2e570c
Upstream: https://gitlab.com/qemu-project/qemu.git Upstream-Commit: d2e570cc0f97b936902a5b1b86b73c0f5998b475
This commit is contained in:
@@ -0,0 +1,510 @@
|
||||
=============================
|
||||
sPAPR Dynamic Reconfiguration
|
||||
=============================
|
||||
|
||||
sPAPR or pSeries guests make use of a facility called dynamic reconfiguration
|
||||
to handle hot plugging of dynamic "physical" resources like PCI cards, or
|
||||
"logical"/para-virtual resources like memory, CPUs, and "physical"
|
||||
host-bridges, which are generally managed by the host/hypervisor and provided
|
||||
to guests as virtualized resources. The specifics of dynamic reconfiguration
|
||||
are documented extensively in section 13 of the Linux on Power Architecture
|
||||
Reference document ([LoPAR]_). This document provides a summary of that
|
||||
information as it applies to the implementation within QEMU.
|
||||
|
||||
Dynamic-reconfiguration Connectors
|
||||
==================================
|
||||
|
||||
To manage hot plug/unplug of these resources, a firmware abstraction known as
|
||||
a Dynamic Resource Connector (DRC) is used to assign a particular dynamic
|
||||
resource to the guest, and provide an interface for the guest to manage
|
||||
configuration/removal of the resource associated with it.
|
||||
|
||||
Device tree description of DRCs
|
||||
===============================
|
||||
|
||||
A set of four Open Firmware device tree array properties are used to describe
|
||||
the name/index/power-domain/type of each DRC allocated to a guest at
|
||||
boot time. There may be multiple sets of these arrays, rooted at different
|
||||
paths in the device tree depending on the type of resource the DRCs manage.
|
||||
|
||||
In some cases, the DRCs themselves may be provided by a dynamic resource,
|
||||
such as the DRCs managing PCI slots on a hot plugged PHB. In this case the
|
||||
arrays would be fetched as part of the device tree retrieval interfaces
|
||||
for hot plugged resources described under :ref:`guest-host-interface`.
|
||||
|
||||
The array properties are described below. Each entry/element in an array
|
||||
describes the DRC identified by the element in the corresponding position
|
||||
of ``ibm,drc-indexes``:
|
||||
|
||||
``ibm,drc-names``
|
||||
-----------------
|
||||
|
||||
First 4-bytes: big-endian (BE) encoded integer denoting the number of entries.
|
||||
|
||||
Each entry: a NULL-terminated ``<name>`` string encoded as a byte array.
|
||||
|
||||
``<name>`` values for logical/virtual resources are defined in the Linux on
|
||||
Power Architecture Reference ([LoPAR]_) section 13.5.2.4, and basically
|
||||
consist of the type of the resource followed by a space and a numerical
|
||||
value that's unique across resources of that type.
|
||||
|
||||
``<name>`` values for "physical" resources such as PCI or VIO devices are
|
||||
defined as being "location codes", which are the "location labels" of each
|
||||
encapsulating device, starting from the chassis down to the individual slot
|
||||
for the device, concatenated by a hyphen. This provides a mapping of
|
||||
resources to a physical location in a chassis for debugging purposes. For
|
||||
QEMU, this mapping is less important, so we assign a location code that
|
||||
conforms to naming specifications, but is simply a location label for the
|
||||
slot by itself to simplify the implementation. The naming convention for
|
||||
location labels is documented in detail in the [LoPAR]_ section 12.3.1.5,
|
||||
and in our case amounts to using ``C<n>`` for PCI/VIO device slots, where
|
||||
``<n>`` is unique across all PCI/VIO device slots.
|
||||
|
||||
``ibm,drc-indexes``
|
||||
-------------------
|
||||
|
||||
First 4-bytes: BE-encoded integer denoting the number of entries.
|
||||
|
||||
Each 4-byte entry: BE-encoded ``<index>`` integer that is unique across all
|
||||
DRCs in the machine.
|
||||
|
||||
``<index>`` is arbitrary, but in the case of QEMU we try to maintain the
|
||||
convention used to assign them to pSeries guests on pHyp (the hypervisor
|
||||
portion of PowerVM):
|
||||
|
||||
``bit[31:28]``: integer encoding of ``<type>``, where ``<type>`` is:
|
||||
|
||||
``1`` for CPU resource.
|
||||
|
||||
``2`` for PHB resource.
|
||||
|
||||
``3`` for VIO resource.
|
||||
|
||||
``4`` for PCI resource.
|
||||
|
||||
``8`` for memory resource.
|
||||
|
||||
``bit[27:0]``: integer encoding of ``<id>``, where ``<id>`` is unique
|
||||
across all resources of specified type.
|
||||
|
||||
``ibm,drc-power-domains``
|
||||
-------------------------
|
||||
|
||||
First 4-bytes: BE-encoded integer denoting the number of entries.
|
||||
|
||||
Each 4-byte entry: 32-bit, BE-encoded ``<index>`` integer that specifies the
|
||||
power domain the resource will be assigned to. In the case of QEMU we
|
||||
associated all resources with a "live insertion" domain, where the power is
|
||||
assumed to be managed automatically. The integer value for this domain is a
|
||||
special value of ``-1``.
|
||||
|
||||
|
||||
``ibm,drc-types``
|
||||
-----------------
|
||||
|
||||
First 4-bytes: BE-encoded integer denoting the number of entries.
|
||||
|
||||
Each entry: a NULL-terminated ``<type>`` string encoded as a byte array.
|
||||
``<type>`` is assigned as follows:
|
||||
|
||||
"CPU" for a CPU.
|
||||
|
||||
"PHB" for a physical host-bridge.
|
||||
|
||||
"SLOT" for a VIO slot.
|
||||
|
||||
"28" for a PCI slot.
|
||||
|
||||
"MEM" for memory resource.
|
||||
|
||||
.. _guest-host-interface:
|
||||
|
||||
Guest->Host interface to manage dynamic resources
|
||||
=================================================
|
||||
|
||||
Each DRC is given a globally unique DRC index, and resources associated with a
|
||||
particular DRC are configured/managed by the guest via a number of RTAS calls
|
||||
which reference individual DRCs based on the DRC index. This can be considered
|
||||
the guest->host interface.
|
||||
|
||||
``rtas-set-power-level``
|
||||
------------------------
|
||||
|
||||
Set the power level for a specified power domain.
|
||||
|
||||
``arg[0]``: integer identifying power domain.
|
||||
|
||||
``arg[1]``: new power level for the domain, ``0-100``.
|
||||
|
||||
``output[0]``: status, ``0`` on success.
|
||||
|
||||
``output[1]``: power level after command.
|
||||
|
||||
``rtas-get-power-level``
|
||||
------------------------
|
||||
|
||||
Get the power level for a specified power domain.
|
||||
|
||||
``arg[0]``: integer identifying power domain.
|
||||
|
||||
``output[0]``: status, ``0`` on success.
|
||||
|
||||
``output[1]``: current power level.
|
||||
|
||||
``rtas-set-indicator``
|
||||
----------------------
|
||||
|
||||
Set the state of an indicator or sensor.
|
||||
|
||||
``arg[0]``: integer identifying sensor/indicator type.
|
||||
|
||||
``arg[1]``: index of sensor, for DR-related sensors this is generally the DRC
|
||||
index.
|
||||
|
||||
``arg[2]``: desired sensor value.
|
||||
|
||||
``output[0]``: status, ``0`` on success.
|
||||
|
||||
For the purpose of this document we focus on the indicator/sensor types
|
||||
associated with a DRC. The types are:
|
||||
|
||||
* ``9001``: ``isolation-state``, controls/indicates whether a device has been
|
||||
made accessible to a guest. Supported sensor values:
|
||||
|
||||
``0``: ``isolate``, device is made inaccessible by guest OS.
|
||||
|
||||
``1``: ``unisolate``, device is made available to guest OS.
|
||||
|
||||
* ``9002``: ``dr-indicator``, controls "visual" indicator associated with
|
||||
device. Supported sensor values:
|
||||
|
||||
``0``: ``inactive``, resource may be safely removed.
|
||||
|
||||
``1``: ``active``, resource is in use and cannot be safely removed.
|
||||
|
||||
``2``: ``identify``, used to visually identify slot for interactive hot plug.
|
||||
|
||||
``3``: ``action``, in most cases, used in the same manner as identify.
|
||||
|
||||
* ``9003``: ``allocation-state``, generally only used for "logical" DR resources
|
||||
to request the allocation/deallocation of a resource prior to acquiring it via
|
||||
``isolation-state->unisolate``, or after releasing it via
|
||||
``isolation-state->isolate``, respectively. For "physical" DR (like PCI
|
||||
hot plug/unplug) the pre-allocation of the resource is implied and this sensor
|
||||
is unused. Supported sensor values:
|
||||
|
||||
``0``: ``unusable``, tell firmware/system the resource can be
|
||||
unallocated/reclaimed and added back to the system resource pool.
|
||||
|
||||
``1``: ``usable``, request the resource be allocated/reserved for use by
|
||||
guest OS.
|
||||
|
||||
``2``: ``exchange``, used to allocate a spare resource to use for fail-over
|
||||
in certain situations. Unused in QEMU.
|
||||
|
||||
``3``: ``recover``, used to reclaim a previously allocated resource that's
|
||||
not currently allocated to the guest OS. Unused in QEMU.
|
||||
|
||||
``rtas-get-sensor-state:``
|
||||
--------------------------
|
||||
|
||||
Used to read an indicator or sensor value.
|
||||
|
||||
``arg[0]``: integer identifying sensor/indicator type.
|
||||
|
||||
``arg[1]``: index of sensor, for DR-related sensors this is generally the DRC
|
||||
index
|
||||
|
||||
``output[0]``: status, 0 on success
|
||||
|
||||
For DR-related operations, the only noteworthy sensor is ``dr-entity-sense``,
|
||||
which has a type value of ``9003``, as ``allocation-state`` does in the case of
|
||||
``rtas-set-indicator``. The semantics/encodings of the sensor values are
|
||||
distinct however.
|
||||
|
||||
Supported sensor values for ``dr-entity-sense`` (``9003``) sensor:
|
||||
|
||||
``0``: empty.
|
||||
|
||||
For physical resources: DRC/slot is empty.
|
||||
|
||||
For logical resources: unused.
|
||||
|
||||
``1``: present.
|
||||
|
||||
For physical resources: DRC/slot is populated with a device/resource.
|
||||
|
||||
For logical resources: resource has been allocated to the DRC.
|
||||
|
||||
``2``: unusable.
|
||||
|
||||
For physical resources: unused.
|
||||
|
||||
For logical resources: DRC has no resource allocated to it.
|
||||
|
||||
``3``: exchange.
|
||||
|
||||
For physical resources: unused.
|
||||
|
||||
For logical resources: resource available for exchange (see
|
||||
``allocation-state`` sensor semantics above).
|
||||
|
||||
``4``: recovery.
|
||||
|
||||
For physical resources: unused.
|
||||
|
||||
For logical resources: resource available for recovery (see
|
||||
``allocation-state`` sensor semantics above).
|
||||
|
||||
``rtas-ibm-configure-connector``
|
||||
--------------------------------
|
||||
|
||||
Used to fetch an OpenFirmware device tree description of the resource associated
|
||||
with a particular DRC.
|
||||
|
||||
``arg[0]``: guest physical address of 4096-byte work area buffer.
|
||||
|
||||
``arg[1]``: 0, or address of additional 4096-byte work area buffer; only
|
||||
non-zero if a prior RTAS response indicated a need for additional memory.
|
||||
|
||||
``output[0]``: status:
|
||||
|
||||
``0``: completed transmittal of device tree node.
|
||||
|
||||
``1``: instruct guest to prepare for next device tree sibling node.
|
||||
|
||||
``2``: instruct guest to prepare for next device tree child node.
|
||||
|
||||
``3``: instruct guest to prepare for next device tree property.
|
||||
|
||||
``4``: instruct guest to ascend to parent device tree node.
|
||||
|
||||
``5``: instruct guest to provide additional work-area buffer via ``arg[1]``.
|
||||
|
||||
``990x``: instruct guest that operation took too long and to try again
|
||||
later.
|
||||
|
||||
The DRC index is encoded in the first 4-bytes of the first work area buffer.
|
||||
Work area (``wa``) layout, using 4-byte offsets:
|
||||
|
||||
``wa[0]``: DRC index of the DRC to fetch device tree nodes from.
|
||||
|
||||
``wa[1]``: ``0`` (hard-coded).
|
||||
|
||||
``wa[2]``:
|
||||
|
||||
For next-sibling/next-child response:
|
||||
|
||||
``wa`` offset of null-terminated string denoting the new node's name.
|
||||
|
||||
For next-property response:
|
||||
|
||||
``wa`` offset of null-terminated string denoting new property's name.
|
||||
|
||||
``wa[3]``: for next-property response (unused otherwise):
|
||||
|
||||
Byte-length of new property's value.
|
||||
|
||||
``wa[4]``: for next-property response (unused otherwise):
|
||||
|
||||
New property's value, encoded as an OFDT-compatible byte array.
|
||||
|
||||
Hot plug/unplug events
|
||||
======================
|
||||
|
||||
For most DR operations, the hypervisor will issue host->guest add/remove events
|
||||
using the EPOW/check-exception notification framework, where the host issues a
|
||||
check-exception interrupt, then provides an RTAS event log via an
|
||||
rtas-check-exception call issued by the guest in response. This framework is
|
||||
documented by PAPR+ v2.7, and already use in by QEMU for generating powerdown
|
||||
requests via EPOW events.
|
||||
|
||||
For DR, this framework has been extended to include hotplug events, which were
|
||||
previously unneeded due to direct manipulation of DR-related guest userspace
|
||||
tools by host-level management such as an HMC. This level of management is not
|
||||
applicable to KVM on Power, hence the reason for extending the notification
|
||||
framework to support hotplug events.
|
||||
|
||||
The format for these EPOW-signalled events is described below under
|
||||
:ref:`hot-plug-unplug-event-structure`. Note that these events are not formally
|
||||
part of the PAPR+ specification, and have been superseded by a newer format,
|
||||
also described below under :ref:`hot-plug-unplug-event-structure`, and so are
|
||||
now deemed a "legacy" format. The formats are similar, but the "modern" format
|
||||
contains additional fields/flags, which are denoted for the purposes of this
|
||||
documentation with ``#ifdef GUEST_SUPPORTS_MODERN`` guards.
|
||||
|
||||
QEMU should assume support only for "legacy" fields/flags unless the guest
|
||||
advertises support for the "modern" format via
|
||||
``ibm,client-architecture-support`` hcall by setting byte 5, bit 6 of it's
|
||||
``ibm,architecture-vec-5`` option vector structure (as described by [LoPAR]_,
|
||||
section B.5.2.3). As with "legacy" format events, "modern" format events are
|
||||
surfaced to the guest via check-exception RTAS calls, but use a dedicated event
|
||||
source to signal the guest. This event source is advertised to the guest by the
|
||||
addition of a ``hot-plug-events`` node under ``/event-sources`` node of the
|
||||
guest's device tree using the standard format described in [LoPAR]_,
|
||||
section B.5.12.2.
|
||||
|
||||
.. _hot-plug-unplug-event-structure:
|
||||
|
||||
Hot plug/unplug event structure
|
||||
===============================
|
||||
|
||||
The hot plug specific payload in QEMU is implemented as follows (with all values
|
||||
encoded in big-endian format):
|
||||
|
||||
.. code-block:: c
|
||||
|
||||
struct rtas_event_log_v6_hp {
|
||||
#define SECTION_ID_HOTPLUG 0x4850 /* HP */
|
||||
struct section_header {
|
||||
uint16_t section_id; /* set to SECTION_ID_HOTPLUG */
|
||||
uint16_t section_length; /* sizeof(rtas_event_log_v6_hp),
|
||||
* plus the length of the DRC name
|
||||
* if a DRC name identifier is
|
||||
* specified for hotplug_identifier
|
||||
*/
|
||||
uint8_t section_version; /* version 1 */
|
||||
uint8_t section_subtype; /* unused */
|
||||
uint16_t creator_component_id; /* unused */
|
||||
} hdr;
|
||||
#define RTAS_LOG_V6_HP_TYPE_CPU 1
|
||||
#define RTAS_LOG_V6_HP_TYPE_MEMORY 2
|
||||
#define RTAS_LOG_V6_HP_TYPE_SLOT 3
|
||||
#define RTAS_LOG_V6_HP_TYPE_PHB 4
|
||||
#define RTAS_LOG_V6_HP_TYPE_PCI 5
|
||||
uint8_t hotplug_type; /* type of resource/device */
|
||||
#define RTAS_LOG_V6_HP_ACTION_ADD 1
|
||||
#define RTAS_LOG_V6_HP_ACTION_REMOVE 2
|
||||
uint8_t hotplug_action; /* action (add/remove) */
|
||||
#define RTAS_LOG_V6_HP_ID_DRC_NAME 1
|
||||
#define RTAS_LOG_V6_HP_ID_DRC_INDEX 2
|
||||
#define RTAS_LOG_V6_HP_ID_DRC_COUNT 3
|
||||
#ifdef GUEST_SUPPORTS_MODERN
|
||||
#define RTAS_LOG_V6_HP_ID_DRC_COUNT_INDEXED 4
|
||||
#endif
|
||||
uint8_t hotplug_identifier; /* type of the resource identifier,
|
||||
* which serves as the discriminator
|
||||
* for the 'drc' union field below
|
||||
*/
|
||||
#ifdef GUEST_SUPPORTS_MODERN
|
||||
uint8_t capabilities; /* capability flags, currently unused
|
||||
* by QEMU
|
||||
*/
|
||||
#else
|
||||
uint8_t reserved;
|
||||
#endif
|
||||
union {
|
||||
uint32_t index; /* DRC index of resource to take action
|
||||
* on
|
||||
*/
|
||||
uint32_t count; /* number of DR resources to take
|
||||
* action on (guest chooses which)
|
||||
*/
|
||||
#ifdef GUEST_SUPPORTS_MODERN
|
||||
struct {
|
||||
uint32_t count; /* number of DR resources to take
|
||||
* action on
|
||||
*/
|
||||
uint32_t index; /* DRC index of first resource to take
|
||||
* action on. guest will take action
|
||||
* on DRC index <index> through
|
||||
* DRC index <index + count - 1> in
|
||||
* sequential order
|
||||
*/
|
||||
} count_indexed;
|
||||
#endif
|
||||
char name[1]; /* string representing the name of the
|
||||
* DRC to take action on
|
||||
*/
|
||||
} drc;
|
||||
} QEMU_PACKED;
|
||||
|
||||
``ibm,lrdr-capacity``
|
||||
=====================
|
||||
|
||||
``ibm,lrdr-capacity`` is a property in the /rtas device tree node that
|
||||
identifies the dynamic reconfiguration capabilities of the guest. It consists
|
||||
of a triple consisting of ``<phys>``, ``<size>`` and ``<maxcpus>``.
|
||||
|
||||
``<phys>``, encoded in BE format represents the maximum address in bytes and
|
||||
hence the maximum memory that can be allocated to the guest.
|
||||
|
||||
``<size>``, encoded in BE format represents the size increments in which
|
||||
memory can be hot-plugged to the guest.
|
||||
|
||||
``<maxcpus>``, a BE-encoded integer, represents the maximum number of
|
||||
processors that the guest can have.
|
||||
|
||||
``pseries`` guests use this property to note the maximum allowed CPUs for the
|
||||
guest.
|
||||
|
||||
``ibm,dynamic-reconfiguration-memory``
|
||||
======================================
|
||||
|
||||
``ibm,dynamic-reconfiguration-memory`` is a device tree node that represents
|
||||
dynamically reconfigurable logical memory blocks (LMB). This node is generated
|
||||
only when the guest advertises the support for it via
|
||||
``ibm,client-architecture-support`` call. Memory that is not dynamically
|
||||
reconfigurable is represented by ``/memory`` nodes. The properties of this node
|
||||
that are of interest to the sPAPR memory hotplug implementation in QEMU are
|
||||
described here.
|
||||
|
||||
``ibm,lmb-size``
|
||||
----------------
|
||||
|
||||
This 64-bit integer defines the size of each dynamically reconfigurable LMB.
|
||||
|
||||
``ibm,associativity-lookup-arrays``
|
||||
-----------------------------------
|
||||
|
||||
This property defines a lookup array in which the NUMA associativity
|
||||
information for each LMB can be found. It is a property encoded array
|
||||
that begins with an integer M, the number of associativity lists followed
|
||||
by an integer N, the number of entries per associativity list and terminated
|
||||
by M associativity lists each of length N integers.
|
||||
|
||||
This property provides the same information as given by ``ibm,associativity``
|
||||
property in a ``/memory`` node. Each assigned LMB has an index value between
|
||||
0 and M-1 which is used as an index into this table to select which
|
||||
associativity list to use for the LMB. This index value for each LMB is defined
|
||||
in ``ibm,dynamic-memory`` property.
|
||||
|
||||
``ibm,dynamic-memory``
|
||||
----------------------
|
||||
|
||||
This property describes the dynamically reconfigurable memory. It is a
|
||||
property encoded array that has an integer N, the number of LMBs followed
|
||||
by N LMB list entries.
|
||||
|
||||
Each LMB list entry consists of the following elements:
|
||||
|
||||
- Logical address of the start of the LMB encoded as a 64-bit integer. This
|
||||
corresponds to ``reg`` property in ``/memory`` node.
|
||||
- DRC index of the LMB that corresponds to ``ibm,my-drc-index`` property
|
||||
in a ``/memory`` node.
|
||||
- Four bytes reserved for expansion.
|
||||
- Associativity list index for the LMB that is used as an index into
|
||||
``ibm,associativity-lookup-arrays`` property described earlier. This is used
|
||||
to retrieve the right associativity list to be used for this LMB.
|
||||
- A 32-bit flags word. The bit at bit position ``0x00000008`` defines whether
|
||||
the LMB is assigned to the partition as of boot time.
|
||||
|
||||
``ibm,dynamic-memory-v2``
|
||||
-------------------------
|
||||
|
||||
This property describes the dynamically reconfigurable memory. This is
|
||||
an alternate and newer way to describe dynamically reconfigurable memory.
|
||||
It is a property encoded array that has an integer N (the number of
|
||||
LMB set entries) followed by N LMB set entries. There is an LMB set entry
|
||||
for each sequential group of LMBs that share common attributes.
|
||||
|
||||
Each LMB set entry consists of the following elements:
|
||||
|
||||
- Number of sequential LMBs in the entry represented by a 32-bit integer.
|
||||
- Logical address of the first LMB in the set encoded as a 64-bit integer.
|
||||
- DRC index of the first LMB in the set.
|
||||
- Associativity list index that is used as an index into
|
||||
``ibm,associativity-lookup-arrays`` property described earlier. This
|
||||
is used to retrieve the right associativity list to be used for all
|
||||
the LMBs in this set.
|
||||
- A 32-bit flags word that applies to all the LMBs in the set.
|
||||
Reference in New Issue
Block a user