--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * CPU Topology
+ *
+ * Copyright IBM Corp. 2022, 2023
+ * Author(s): Pierre Morel <pmorel@linux.ibm.com>
+ *
+ * S390 topology handling can be divided in two parts:
+ *
+ * - The first part in this file is taking care of all common functions
+ * used by KVM and TCG to create and modify the topology.
+ *
+ * - The second part, building the topology information data for the
+ * guest with CPU and KVM specificity will be implemented inside
+ * the target/s390/kvm sub tree.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "hw/qdev-properties.h"
+#include "hw/boards.h"
+#include "target/s390x/cpu.h"
+#include "hw/s390x/s390-virtio-ccw.h"
+#include "hw/s390x/cpu-topology.h"
+
+/*
+ * s390_topology is used to keep the topology information.
+ * .cores_per_socket: tracks information on the count of cores
+ * per socket.
+ */
+S390Topology s390_topology = {
+ /* will be initialized after the CPU model is realized */
+ .cores_per_socket = NULL,
+};
+
+/**
+ * s390_socket_nb:
+ * @cpu: s390x CPU
+ *
+ * Returns the socket number used inside the cores_per_socket array
+ * for a topology tree entry
+ */
+static int s390_socket_nb_from_ids(int drawer_id, int book_id, int socket_id)
+{
+ return (drawer_id * current_machine->smp.books + book_id) *
+ current_machine->smp.sockets + socket_id;
+}
+
+/**
+ * s390_socket_nb:
+ * @cpu: s390x CPU
+ *
+ * Returns the socket number used inside the cores_per_socket array
+ * for a cpu.
+ */
+static int s390_socket_nb(S390CPU *cpu)
+{
+ return s390_socket_nb_from_ids(cpu->env.drawer_id, cpu->env.book_id,
+ cpu->env.socket_id);
+}
+
+/**
+ * s390_has_topology:
+ *
+ * Return: true if the topology is supported by the machine.
+ */
+bool s390_has_topology(void)
+{
+ return false;
+}
+
+/**
+ * s390_topology_init:
+ * @ms: the machine state where the machine topology is defined
+ *
+ * Keep track of the machine topology.
+ *
+ * Allocate an array to keep the count of cores per socket.
+ * The index of the array starts at socket 0 from book 0 and
+ * drawer 0 up to the maximum allowed by the machine topology.
+ */
+static void s390_topology_init(MachineState *ms)
+{
+ CpuTopology *smp = &ms->smp;
+
+ s390_topology.cores_per_socket = g_new0(uint8_t, smp->sockets *
+ smp->books * smp->drawers);
+}
+
+/**
+ * s390_topology_cpu_default:
+ * @cpu: pointer to a S390CPU
+ * @errp: Error pointer
+ *
+ * Setup the default topology if no attributes are already set.
+ * Passing a CPU with some, but not all, attributes set is considered
+ * an error.
+ *
+ * The function calculates the (drawer_id, book_id, socket_id)
+ * topology by filling the cores starting from the first socket
+ * (0, 0, 0) up to the last (smp->drawers, smp->books, smp->sockets).
+ *
+ * CPU type and dedication have defaults values set in the
+ * s390x_cpu_properties, entitlement must be adjust depending on the
+ * dedication.
+ *
+ * Returns false if it is impossible to setup a default topology
+ * true otherwise.
+ */
+static bool s390_topology_cpu_default(S390CPU *cpu, Error **errp)
+{
+ CpuTopology *smp = ¤t_machine->smp;
+ CPUS390XState *env = &cpu->env;
+
+ /* All geometry topology attributes must be set or all unset */
+ if ((env->socket_id < 0 || env->book_id < 0 || env->drawer_id < 0) &&
+ (env->socket_id >= 0 || env->book_id >= 0 || env->drawer_id >= 0)) {
+ error_setg(errp,
+ "Please define all or none of the topology geometry attributes");
+ return false;
+ }
+
+ /* If one value is unset all are unset -> calculate defaults */
+ if (env->socket_id < 0) {
+ env->socket_id = s390_std_socket(env->core_id, smp);
+ env->book_id = s390_std_book(env->core_id, smp);
+ env->drawer_id = s390_std_drawer(env->core_id, smp);
+ }
+
+ /*
+ * When the user specifies the entitlement as 'auto' on the command line,
+ * QEMU will set the entitlement as:
+ * Medium when the CPU is not dedicated.
+ * High when dedicated is true.
+ */
+ if (env->entitlement == S390_CPU_ENTITLEMENT_AUTO) {
+ if (env->dedicated) {
+ env->entitlement = S390_CPU_ENTITLEMENT_HIGH;
+ } else {
+ env->entitlement = S390_CPU_ENTITLEMENT_MEDIUM;
+ }
+ }
+ return true;
+}
+
+/**
+ * s390_topology_check:
+ * @socket_id: socket to check
+ * @book_id: book to check
+ * @drawer_id: drawer to check
+ * @entitlement: entitlement to check
+ * @dedicated: dedication to check
+ * @errp: Error pointer
+ *
+ * The function checks if the topology
+ * attributes fits inside the system topology.
+ *
+ * Returns false if the specified topology does not match with
+ * the machine topology.
+ */
+static bool s390_topology_check(uint16_t socket_id, uint16_t book_id,
+ uint16_t drawer_id, uint16_t entitlement,
+ bool dedicated, Error **errp)
+{
+ CpuTopology *smp = ¤t_machine->smp;
+
+ if (socket_id >= smp->sockets) {
+ error_setg(errp, "Unavailable socket: %d", socket_id);
+ return false;
+ }
+ if (book_id >= smp->books) {
+ error_setg(errp, "Unavailable book: %d", book_id);
+ return false;
+ }
+ if (drawer_id >= smp->drawers) {
+ error_setg(errp, "Unavailable drawer: %d", drawer_id);
+ return false;
+ }
+ if (entitlement >= S390_CPU_ENTITLEMENT__MAX) {
+ error_setg(errp, "Unknown entitlement: %d", entitlement);
+ return false;
+ }
+ if (dedicated && (entitlement == S390_CPU_ENTITLEMENT_LOW ||
+ entitlement == S390_CPU_ENTITLEMENT_MEDIUM)) {
+ error_setg(errp, "A dedicated CPU implies high entitlement");
+ return false;
+ }
+ return true;
+}
+
+/**
+ * s390_update_cpu_props:
+ * @ms: the machine state
+ * @cpu: the CPU for which to update the properties from the environment.
+ *
+ */
+static void s390_update_cpu_props(MachineState *ms, S390CPU *cpu)
+{
+ CpuInstanceProperties *props;
+
+ props = &ms->possible_cpus->cpus[cpu->env.core_id].props;
+
+ props->socket_id = cpu->env.socket_id;
+ props->book_id = cpu->env.book_id;
+ props->drawer_id = cpu->env.drawer_id;
+}
+
+/**
+ * s390_topology_setup_cpu:
+ * @ms: MachineState used to initialize the topology structure on
+ * first call.
+ * @cpu: the new S390CPU to insert in the topology structure
+ * @errp: the error pointer
+ *
+ * Called from CPU hotplug to check and setup the CPU attributes
+ * before the CPU is inserted in the topology.
+ * There is no need to update the MTCR explicitly here because it
+ * will be updated by KVM on creation of the new CPU.
+ */
+void s390_topology_setup_cpu(MachineState *ms, S390CPU *cpu, Error **errp)
+{
+ int entry;
+
+ /*
+ * We do not want to initialize the topology if the CPU model
+ * does not support topology, consequently, we have to wait for
+ * the first CPU to be realized, which realizes the CPU model
+ * to initialize the topology structures.
+ *
+ * s390_topology_setup_cpu() is called from the CPU hotplug.
+ */
+ if (!s390_topology.cores_per_socket) {
+ s390_topology_init(ms);
+ }
+
+ if (!s390_topology_cpu_default(cpu, errp)) {
+ return;
+ }
+
+ if (!s390_topology_check(cpu->env.socket_id, cpu->env.book_id,
+ cpu->env.drawer_id, cpu->env.entitlement,
+ cpu->env.dedicated, errp)) {
+ return;
+ }
+
+ /* Do we still have space in the socket */
+ entry = s390_socket_nb(cpu);
+ if (s390_topology.cores_per_socket[entry] >= ms->smp.cores) {
+ error_setg(errp, "No more space on this socket");
+ return;
+ }
+
+ /* Update the count of cores in sockets */
+ s390_topology.cores_per_socket[entry] += 1;
+
+ /* topology tree is reflected in props */
+ s390_update_cpu_props(ms, cpu);
+}
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