Hi, This new series adds three features: 1) the implementation of drawers and books in the topology geometry and adds polarization and dedication as topology modifiers. 2) The Maximum Nested topology level (MNEST) can be read with SCLP read info. 3) Dynamic modification of the CPU topology using the QEMU monitor. Implementation discussions ========================== CPU models ---------- Since the facility 11, S390_FEAT_CONFIGURATION_TOPOLOGY is already in the CPU model for old QEMU we could not activate it as usual from KVM but needed a KVM capability: KVM_CAP_S390_CPU_TOPOLOGY. Checking and enabling this capability enables facility 11, S390_FEAT_CONFIGURATION_TOPOLOGY. It is the responsibility of the admin to ensure the same CPU model for source and target host in a migration. Migration --------- When the target guest is started, the Multi-processor Topology Change Report (MTCR) bit is set during the creation of the vCPU by KVM. We do not need to migrate its state, in the worst case, the target guest will see the MTCR and actualize its view of the topology without necessity, but this will be done only one time. Reset ----- Reseting the topology is done during subsystem reset, the polarization is reset to horizontal polarization. Topology attributes ------------------- The topology attributes are carried by the CPU object and defined on object creation. In the case the new attributes, socket, book, drawer, dedicated, polarity are not provided QEMU provides defaults values. - Geometry defaults The geometry default are based on the core-id of the core to fill the geometry in a monotone way starting with drawer 0, book 0, and filling socket 0 with the number of cores per socket, then filling socket 1, socket 2 ... etc until the book is complete and all books until the first drawer is complete before starting with the next drawer. This allows to keep existing start scripts and Libvirt existing interface until it is extended. - Modifiers defaults Default polarization is horizontal Default dedication is not dedicated. Dynamic topology modification ----------------------------- QAPI interface is extended with: - a command: 'change-topology' - a query: 'query-topology' - a event: 'POLARITY_CHANGE' The admin may use query-topology to verify the topology provided to the guest and change-topology to modify it. The event POLARITY_CHANGE is sent when the guest uses the PTF instruction to request a polarization change. In that case, the admin is supposed to modify the CPU provisioning accordingly. Testing ======= To use the QEMU patches, you will need Linux V6-rc1 or newer, or use the following Linux mainline patches: f5ecfee94493 2022-07-20 KVM: s390: resetting the Topology-Change-Report 24fe0195bc19 2022-07-20 KVM: s390: guest support for topology function 0130337ec45b 2022-07-20 KVM: s390: Cleanup ipte lock access and SIIF fac.. Currently this code is for KVM only, I have no idea if it is interesting to provide a TCG patch. If ever it will be done in another series. Documentation ============= To have a better understanding of the S390x CPU Topology and its implementation in QEMU you can have a look at the documentation in the last patch of this series. The admin will want to match the host and the guest topology, taking into account that the guest does not recognize multithreading. Consequently, two vCPU assigned to threads of the same real CPU should preferably be assigned to the same socket of the guest machine. Regards, Pierre Pierre Morel (11): s390x/cpu topology: adding s390 specificities to CPU topology s390x/cpu topology: add topology entries on CPU hotplug target/s390x/cpu topology: handle STSI(15) and build the SYSIB s390x/sclp: reporting the maximum nested topology entries s390x/cpu topology: resetting the Topology-Change-Report s390x/cpu topology: interception of PTF instruction target/s390x/cpu topology: activating CPU topology qapi/s390/cpu topology: change-topology monitor command qapi/s390/cpu topology: monitor query topology information qapi/s390/cpu topology: POLARITY_CHANGE qapi event docs/s390x/cpu topology: document s390x cpu topology docs/system/s390x/cpu-topology.rst | 292 ++++++++++++++ docs/system/target-s390x.rst | 1 + qapi/machine-target.json | 116 ++++++ qapi/machine.json | 14 +- include/hw/boards.h | 10 +- include/hw/s390x/cpu-topology.h | 77 ++++ include/hw/s390x/s390-virtio-ccw.h | 6 + include/hw/s390x/sclp.h | 4 +- include/monitor/hmp.h | 2 + target/s390x/cpu.h | 86 ++++ target/s390x/kvm/kvm_s390x.h | 1 + hw/core/machine-smp.c | 48 ++- hw/core/machine.c | 4 + hw/s390x/cpu-topology.c | 604 +++++++++++++++++++++++++++++ hw/s390x/s390-virtio-ccw.c | 13 + hw/s390x/sclp.c | 4 + softmmu/vl.c | 6 + target/s390x/cpu-sysemu.c | 29 ++ target/s390x/cpu.c | 10 + target/s390x/cpu_models.c | 1 + target/s390x/kvm/cpu_topology.c | 136 +++++++ target/s390x/kvm/kvm.c | 46 ++- hmp-commands-info.hx | 16 + hmp-commands.hx | 16 + hw/s390x/meson.build | 1 + qemu-options.hx | 6 +- target/s390x/kvm/meson.build | 3 +- 27 files changed, 1537 insertions(+), 15 deletions(-) create mode 100644 docs/system/s390x/cpu-topology.rst create mode 100644 include/hw/s390x/cpu-topology.h create mode 100644 hw/s390x/cpu-topology.c create mode 100644 target/s390x/kvm/cpu_topology.c -- 2.31.1 Since v13: - Suppress the topology device to simplify the code (Cedric) - moved reset of MTCR from device reset into subsystem reset and removed previous reviewed-by from Nico and Janis - No need for Migration - No need for machine dependencies (Christian, Thomas) - Adding all features, drawer/book and dynamic (Cedric) - since v12 - suppress new CPU flag "disable-topology" just use ctop - no use of special fields in CCW machine or in CPU - modifications in documentation - insert documentation in tree (Cedric) - moved cpu-topology.c from target/s390 to target/s390/kvm to compile smoothly (without topology) for TCG (Cedric) - since v11 - new CPU flag "disable-topology" I would have take "topology" if I was able to have it false on default. (Christian, Thomas) - Build the topology during the interception of the STSI instruction. (Cedric) - return CC3 in case the calculated SYSIB length is greater than 4096. (Janis) - minor corections on documentation - since v10 - change machine attribute "topology-disable" to "topology" (Cedric) - Add preliminary patch for machine properties (Cedric) - Use next machine as 7.2 (Cedric / Connie) - Remove unecessary mutex (Thomas) - use ENOTSUP return value for kvm_s390_topology_set_mtcr() (Cedric) - Add explanation on container and cpu TLEs (Thomas) - use again cpu and socket count in topology structure (Cedric) - Suppress the S390TopoTLE structure and integrate the TLE masks to the socket structure. (-) - the STSI instruction now finds the topology from the machine (Cedric) - since v9 - remove books and drawers - remove thread denying and replace with a merge of cores * threads to specify the CPUs available to the guest - add a class option to avoid topology on older machines (Cedric) - Allocate a SYSIB buffer of the maximal length to avoid overflow. (Nico, Janis) - suppress redundancy of smp parameters in topology and use directly the machine smp structure - Early check for topology support (Cedric) - since v8 - Linux patches are now mainline - simplification of the implementation (Janis) - Migration, new machine definition (Thomas) - Documentation - since v7 - Coherence with the Linux patch series changes for MTCR get (Pierre) - check return values during new CPU creation (Thomas) - Improving codding style and argument usages (Thomas) - since v6 - Changes on smp args in qemu-options (Daniel) - changed comments in machine.jason (Daniel) - Added reset (Janosch) - since v5 - rebasing on newer QEMU version - reworked most lines above 80 characters. - since v4 - Added drawer and books to topology - Added numa topology - Added documentation - since v3 - Added migration (Thomas) - Separated STSI instruction from KVM to prepare TCG (Thomas) - Take care of endianess to prepare TCG (Thomas) - Added comments on STSI CPU container and PFT instruction (Thomas) - Moved enabling the instructions as the last patch (Thomas)
