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Merge tag 'pull-request-2023-10-20' of https://gitlab.com/thuth/qemu into staging
* s390x CPU topology support * Simplify the KVM register synchronization code * Disable the analyze-migration.py test on s390x # -----BEGIN PGP SIGNATURE----- # # iQJFBAABCAAvFiEEJ7iIR+7gJQEY8+q5LtnXdP5wLbUFAmUyDYMRHHRodXRoQHJl # ZGhhdC5jb20ACgkQLtnXdP5wLbUlgBAAkF3dvW0vMcb653sCI5vt2GHIvQQtc2Rw # ghRRcTBZ7wyVxKHtqohCh7/byzDW5YEuCWUyLsc2oIz/84pc00VR/5Ng1EAxLAfe # mvzzjr4jX96SmoO0DbJpqJQXaUPNYdmoshbRL0I3wkIfGtkvGRM8zHZuYINOg0hw # bH6gWZ2QL/NFjXh0uAOaJB1+hRtPWvHD2rnVt0g9U9W5QhRxGJqti5YEaLBH7hh5 # RydsquRZ/E6uFw4pMjjvCxDaswPwejddrP2YeR5Fd5Zo+Kzp53r9Hf/eJwlZ8yFL # 5f1dRb19NZYpW1hZuJVOP8tkPydYxAM85vkUunI7Qg4gez5KI0Nz6hQozw6ufMlQ # r8L17fwQMsCrwcRypImYNXyyrtHlNH5Y8FjqTct8aK64Bw3e7Qqi7d3ybFAuYZ+D # k2EJ8Rlwhbg69h+Q+ucHx4NkYu9+2MFS6G7w5EcM6xl3WHSwUxh9orlEMsIkyHS3 # OMFMTr1jjfFdEN6EafhPwFE/xKglFF2Fe3u6NoR+5pkv3UA5Z87giitxoekYecpH # J96P3anORpWW75qvOF+nccqrd7OrUL1/yYdOyJh5Tkm0oCIeQ9E5extVf3Gne3E/ # yWzr00GJRiHFO2qbGStgKHTQLItgQpccwNpSzEdgHCqwLbXl6e3Hoq42VIFOlbN/ # ZtgpyUkuYyQ= # =xDb+ # -----END PGP SIGNATURE----- # gpg: Signature made Thu 19 Oct 2023 22:17:55 PDT # gpg: using RSA key 27B88847EEE0250118F3EAB92ED9D774FE702DB5 # gpg: issuer "thuth@redhat.com" # gpg: Good signature from "Thomas Huth <th.huth@gmx.de>" [full] # gpg: aka "Thomas Huth <thuth@redhat.com>" [full] # gpg: aka "Thomas Huth <huth@tuxfamily.org>" [full] # gpg: aka "Thomas Huth <th.huth@posteo.de>" [unknown] # Primary key fingerprint: 27B8 8847 EEE0 2501 18F3 EAB9 2ED9 D774 FE70 2DB5 * tag 'pull-request-2023-10-20' of https://gitlab.com/thuth/qemu: (24 commits) tests/qtest/migration-test: Disable the analyze-migration.py test on s390x target/s390x/kvm: Simplify the GPRs, ACRs, CRs and prefix synchronization code target/s390x/kvm: Turn KVM_CAP_SYNC_REGS into a hard requirement tests/avocado: s390x cpu topology bad move tests/avocado: s390x cpu topology dedicated errors tests/avocado: s390x cpu topology test socket full tests/avocado: s390x cpu topology test dedicated CPU tests/avocado: s390x cpu topology entitlement tests tests/avocado: s390x cpu topology polarization tests/avocado: s390x cpu topology core docs/s390x/cpu topology: document s390x cpu topology qapi/s390x/cpu topology: add query-s390x-cpu-polarization command qapi/s390x/cpu topology: CPU_POLARIZATION_CHANGE QAPI event machine: adding s390 topology to info hotpluggable-cpus machine: adding s390 topology to query-cpu-fast qapi/s390x/cpu topology: set-cpu-topology qmp command target/s390x/cpu topology: activate CPU topology s390x/cpu topology: interception of PTF instruction s390x/cpu topology: resetting the Topology-Change-Report s390x/sclp: reporting the maximum nested topology entries ... Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi
@ -14,6 +14,7 @@ Details about QEMU's various subsystems including how to add features to them.
|
||||
migration
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multi-process
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reset
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s390-cpu-topology
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s390-dasd-ipl
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tracing
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vfio-migration
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170
docs/devel/s390-cpu-topology.rst
Normal file
170
docs/devel/s390-cpu-topology.rst
Normal file
@ -0,0 +1,170 @@
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QAPI interface for S390 CPU topology
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====================================
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||||
The following sections will explain the QAPI interface for S390 CPU topology
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with the help of exemplary output.
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For this, let's assume that QEMU has been started with the following
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command, defining 4 CPUs, where CPU[0] is defined by the -smp argument and will
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have default values:
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.. code-block:: bash
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qemu-system-s390x \
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-enable-kvm \
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-cpu z14,ctop=on \
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-smp 1,drawers=3,books=3,sockets=2,cores=2,maxcpus=36 \
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-device z14-s390x-cpu,core-id=19,entitlement=high \
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-device z14-s390x-cpu,core-id=11,entitlement=low \
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-device z14-s390x-cpu,core-id=112,entitlement=high \
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...
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Additions to query-cpus-fast
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----------------------------
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The command query-cpus-fast allows querying the topology tree and
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modifiers for all configured vCPUs.
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.. code-block:: QMP
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{ "execute": "query-cpus-fast" }
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{
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"return": [
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{
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"dedicated": false,
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"thread-id": 536993,
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"props": {
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"core-id": 0,
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"socket-id": 0,
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"drawer-id": 0,
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"book-id": 0
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},
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"cpu-state": "operating",
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"entitlement": "medium",
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"qom-path": "/machine/unattached/device[0]",
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"cpu-index": 0,
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"target": "s390x"
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},
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{
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"dedicated": false,
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"thread-id": 537003,
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"props": {
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"core-id": 19,
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"socket-id": 1,
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"drawer-id": 0,
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"book-id": 2
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},
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"cpu-state": "operating",
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"entitlement": "high",
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"qom-path": "/machine/peripheral-anon/device[0]",
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"cpu-index": 19,
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"target": "s390x"
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},
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{
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"dedicated": false,
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"thread-id": 537004,
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"props": {
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"core-id": 11,
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"socket-id": 1,
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"drawer-id": 0,
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"book-id": 1
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},
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"cpu-state": "operating",
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"entitlement": "low",
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"qom-path": "/machine/peripheral-anon/device[1]",
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"cpu-index": 11,
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"target": "s390x"
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},
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{
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"dedicated": true,
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"thread-id": 537005,
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"props": {
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"core-id": 112,
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"socket-id": 0,
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"drawer-id": 3,
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"book-id": 2
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},
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"cpu-state": "operating",
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"entitlement": "high",
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"qom-path": "/machine/peripheral-anon/device[2]",
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"cpu-index": 112,
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"target": "s390x"
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}
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]
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}
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QAPI command: set-cpu-topology
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------------------------------
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The command set-cpu-topology allows modifying the topology tree
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or the topology modifiers of a vCPU in the configuration.
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.. code-block:: QMP
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{ "execute": "set-cpu-topology",
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"arguments": {
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"core-id": 11,
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"socket-id": 0,
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"book-id": 0,
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"drawer-id": 0,
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"entitlement": "low",
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"dedicated": false
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}
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}
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{"return": {}}
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The core-id parameter is the only mandatory parameter and every
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unspecified parameter keeps its previous value.
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QAPI event CPU_POLARIZATION_CHANGE
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----------------------------------
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When a guest requests a modification of the polarization,
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QEMU sends a CPU_POLARIZATION_CHANGE event.
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When requesting the change, the guest only specifies horizontal or
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vertical polarization.
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It is the job of the entity administrating QEMU to set the dedication and fine
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grained vertical entitlement in response to this event.
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Note that a vertical polarized dedicated vCPU can only have a high
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entitlement, giving 6 possibilities for vCPU polarization:
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- Horizontal
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- Horizontal dedicated
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- Vertical low
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- Vertical medium
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- Vertical high
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- Vertical high dedicated
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Example of the event received when the guest issues the CPU instruction
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Perform Topology Function PTF(0) to request an horizontal polarization:
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.. code-block:: QMP
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{
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"timestamp": {
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"seconds": 1687870305,
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"microseconds": 566299
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},
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"event": "CPU_POLARIZATION_CHANGE",
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"data": {
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"polarization": "horizontal"
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}
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}
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QAPI query command: query-s390x-cpu-polarization
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------------------------------------------------
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The query command query-s390x-cpu-polarization returns the current
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CPU polarization of the machine.
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In this case the guest previously issued a PTF(1) to request vertical polarization:
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.. code-block:: QMP
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{ "execute": "query-s390x-cpu-polarization" }
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{
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"return": {
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"polarization": "vertical"
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}
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}
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244
docs/system/s390x/cpu-topology.rst
Normal file
244
docs/system/s390x/cpu-topology.rst
Normal file
@ -0,0 +1,244 @@
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.. _cpu-topology-s390x:
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CPU topology on s390x
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=====================
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Since QEMU 8.2, CPU topology on s390x provides up to 3 levels of
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topology containers: drawers, books and sockets. They define a
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tree-shaped hierarchy.
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The socket container has one or more CPU entries.
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Each of these CPU entries consists of a bitmap and three CPU attributes:
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- CPU type
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- entitlement
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- dedication
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Each bit set in the bitmap correspond to a core-id of a vCPU with matching
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attributes.
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This documentation provides general information on S390 CPU topology,
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how to enable it and explains the new CPU attributes.
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For information on how to modify the S390 CPU topology and how to
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monitor polarization changes, see ``docs/devel/s390-cpu-topology.rst``.
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Prerequisites
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-------------
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To use the CPU topology, you need to run with KVM on a s390x host that
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uses the Linux kernel v6.0 or newer (which provide the so-called
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``KVM_CAP_S390_CPU_TOPOLOGY`` capability that allows QEMU to signal the
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CPU topology facility via the so-called STFLE bit 11 to the VM).
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Enabling CPU topology
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---------------------
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Currently, CPU topology is only enabled in the host model by default.
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Enabling CPU topology in a CPU model is done by setting the CPU flag
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``ctop`` to ``on`` as in:
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.. code-block:: bash
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||||
-cpu gen16b,ctop=on
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Having the topology disabled by default allows migration between
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old and new QEMU without adding new flags.
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Default topology usage
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----------------------
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The CPU topology can be specified on the QEMU command line
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with the ``-smp`` or the ``-device`` QEMU command arguments.
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Note also that since 7.2 threads are no longer supported in the topology
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and the ``-smp`` command line argument accepts only ``threads=1``.
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If none of the containers attributes (drawers, books, sockets) are
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specified for the ``-smp`` flag, the number of these containers
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is 1.
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Thus the following two options will result in the same topology:
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.. code-block:: bash
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-smp cpus=5,drawer=1,books=1,sockets=8,cores=4,maxcpus=32
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and
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.. code-block:: bash
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-smp cpus=5,sockets=8,cores=4,maxcpus=32
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|
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When a CPU is defined by the ``-smp`` command argument, its position
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inside the topology is calculated by adding the CPUs to the topology
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based on the core-id starting with core-0 at position 0 of socket-0,
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book-0, drawer-0 and filling all CPUs of socket-0 before filling socket-1
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of book-0 and so on up to the last socket of the last book of the last
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drawer.
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When a CPU is defined by the ``-device`` command argument, the
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tree topology attributes must all be defined or all not defined.
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||||
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||||
.. code-block:: bash
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||||
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-device gen16b-s390x-cpu,drawer-id=1,book-id=1,socket-id=2,core-id=1
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||||
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or
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.. code-block:: bash
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||||
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-device gen16b-s390x-cpu,core-id=1,dedicated=true
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|
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If none of the tree attributes (drawer, book, sockets), are specified
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for the ``-device`` argument, like for all CPUs defined with the ``-smp``
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command argument the topology tree attributes will be set by simply
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adding the CPUs to the topology based on the core-id.
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||||
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||||
QEMU will not try to resolve collisions and will report an error if the
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CPU topology defined explicitly or implicitly on a ``-device``
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||||
argument collides with the definition of a CPU implicitly defined
|
||||
on the ``-smp`` argument.
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|
||||
When the topology modifier attributes are not defined for the
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``-device`` command argument they takes following default values:
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||||
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||||
- dedicated: ``false``
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||||
- entitlement: ``medium``
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||||
|
||||
|
||||
Hot plug
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||||
++++++++
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||||
|
||||
New CPUs can be plugged using the device_add hmp command as in:
|
||||
|
||||
.. code-block:: bash
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||||
|
||||
(qemu) device_add gen16b-s390x-cpu,core-id=9
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||||
|
||||
The placement of the CPU is derived from the core-id as described above.
|
||||
|
||||
The topology can of course also be fully defined:
|
||||
|
||||
.. code-block:: bash
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||||
|
||||
(qemu) device_add gen16b-s390x-cpu,drawer-id=1,book-id=1,socket-id=2,core-id=1
|
||||
|
||||
|
||||
Examples
|
||||
++++++++
|
||||
|
||||
In the following machine we define 8 sockets with 4 cores each.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
$ qemu-system-s390x -m 2G \
|
||||
-cpu gen16b,ctop=on \
|
||||
-smp cpus=5,sockets=8,cores=4,maxcpus=32 \
|
||||
-device host-s390x-cpu,core-id=14 \
|
||||
|
||||
A new CPUs can be plugged using the device_add hmp command as before:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
(qemu) device_add gen16b-s390x-cpu,core-id=9
|
||||
|
||||
The core-id defines the placement of the core in the topology by
|
||||
starting with core 0 in socket 0 up to maxcpus.
|
||||
|
||||
In the example above:
|
||||
|
||||
* There are 5 CPUs provided to the guest with the ``-smp`` command line
|
||||
They will take the core-ids 0,1,2,3,4
|
||||
As we have 4 cores in a socket, we have 4 CPUs provided
|
||||
to the guest in socket 0, with core-ids 0,1,2,3.
|
||||
The last CPU, with core-id 4, will be on socket 1.
|
||||
|
||||
* the core with ID 14 provided by the ``-device`` command line will
|
||||
be placed in socket 3, with core-id 14
|
||||
|
||||
* the core with ID 9 provided by the ``device_add`` qmp command will
|
||||
be placed in socket 2, with core-id 9
|
||||
|
||||
|
||||
Polarization, entitlement and dedication
|
||||
----------------------------------------
|
||||
|
||||
Polarization
|
||||
++++++++++++
|
||||
|
||||
The polarization affects how the CPUs of a shared host are utilized/distributed
|
||||
among guests.
|
||||
The guest determines the polarization by using the PTF instruction.
|
||||
|
||||
Polarization defines two models of CPU provisioning: horizontal
|
||||
and vertical.
|
||||
|
||||
The horizontal polarization is the default model on boot and after
|
||||
subsystem reset. When horizontal polarization is in effect all vCPUs should
|
||||
have about equal resource provisioning.
|
||||
|
||||
In the vertical polarization model vCPUs are unequal, but overall more resources
|
||||
might be available.
|
||||
The guest can make use of the vCPU entitlement information provided by the host
|
||||
to optimize kernel thread scheduling.
|
||||
|
||||
A subsystem reset puts all vCPU of the configuration into the
|
||||
horizontal polarization.
|
||||
|
||||
Entitlement
|
||||
+++++++++++
|
||||
|
||||
The vertical polarization specifies that the guest's vCPU can get
|
||||
different real CPU provisioning:
|
||||
|
||||
- a vCPU with vertical high entitlement specifies that this
|
||||
vCPU gets 100% of the real CPU provisioning.
|
||||
|
||||
- a vCPU with vertical medium entitlement specifies that this
|
||||
vCPU shares the real CPU with other vCPUs.
|
||||
|
||||
- a vCPU with vertical low entitlement specifies that this
|
||||
vCPU only gets real CPU provisioning when no other vCPUs needs it.
|
||||
|
||||
In the case a vCPU with vertical high entitlement does not use
|
||||
the real CPU, the unused "slack" can be dispatched to other vCPU
|
||||
with medium or low entitlement.
|
||||
|
||||
A vCPU can be "dedicated" in which case the vCPU is fully dedicated to a single
|
||||
real CPU.
|
||||
|
||||
The dedicated bit is an indication of affinity of a vCPU for a real CPU
|
||||
while the entitlement indicates the sharing or exclusivity of use.
|
||||
|
||||
Defining the topology on the command line
|
||||
-----------------------------------------
|
||||
|
||||
The topology can entirely be defined using -device cpu statements,
|
||||
with the exception of CPU 0 which must be defined with the -smp
|
||||
argument.
|
||||
|
||||
For example, here we set the position of the cores 1,2,3 to
|
||||
drawer 1, book 1, socket 2 and cores 0,9 and 14 to drawer 0,
|
||||
book 0, socket 0 without defining entitlement or dedication.
|
||||
Core 4 will be set on its default position on socket 1
|
||||
(since we have 4 core per socket) and we define it as dedicated and
|
||||
with vertical high entitlement.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
$ qemu-system-s390x -m 2G \
|
||||
-cpu gen16b,ctop=on \
|
||||
-smp cpus=1,sockets=8,cores=4,maxcpus=32 \
|
||||
\
|
||||
-device gen16b-s390x-cpu,drawer-id=1,book-id=1,socket-id=2,core-id=1 \
|
||||
-device gen16b-s390x-cpu,drawer-id=1,book-id=1,socket-id=2,core-id=2 \
|
||||
-device gen16b-s390x-cpu,drawer-id=1,book-id=1,socket-id=2,core-id=3 \
|
||||
\
|
||||
-device gen16b-s390x-cpu,drawer-id=0,book-id=0,socket-id=0,core-id=9 \
|
||||
-device gen16b-s390x-cpu,drawer-id=0,book-id=0,socket-id=0,core-id=14 \
|
||||
\
|
||||
-device gen16b-s390x-cpu,core-id=4,dedicated=on,entitlement=high
|
||||
|
||||
The entitlement defined for the CPU 4 will only be used after the guest
|
||||
successfully enables vertical polarization by using the PTF instruction.
|
||||
@ -34,3 +34,4 @@ Architectural features
|
||||
.. toctree::
|
||||
s390x/bootdevices
|
||||
s390x/protvirt
|
||||
s390x/cpu-topology
|
||||
|
||||
Reference in New Issue
Block a user