0180a74463
From s390_possible_cpu_arch_ids() in hw/s390x/s390-virtio-ccw.c, the "core-id" is the index of possible_cpus->cpus[], so it should only be less than possible_cpus->len, which is equal to ms->smp.max_cpus. Fix the wrong "core-id" 112, because it isn't less than maxcpus (36) in -smp, and the valid core ids are 0-35 inclusive. Signed-off-by: Zhao Liu <zhao1.liu@intel.com> Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com> Message-ID: <20231127134917.568552-1-zhao1.liu@linux.intel.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
171 lines
4.2 KiB
ReStructuredText
171 lines
4.2 KiB
ReStructuredText
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=12,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": 12,
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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": 12,
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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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