Add topological relationship for Loongarch VCPU and initialize
topology member variables, the topo information includes socket-id,
core-id and thread-id. For cold-plug CPUs, its topo information
is calculated from physical cpuid, and for hot-cpu CPUs its physical
cpuid is calculated from topo information.

Co-developed-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
---
 docs/system/loongarch/virt.rst | 31 ++++++++++++++++
 hw/loongarch/virt.c            | 67 ++++++++++++++++++++++++++++------
 target/loongarch/cpu.c         | 12 ++++++
 target/loongarch/cpu.h         | 17 +++++++++
 4 files changed, 115 insertions(+), 12 deletions(-)

diff --git a/docs/system/loongarch/virt.rst b/docs/system/loongarch/virt.rst
index 172fba079e..8daf60785f 100644
--- a/docs/system/loongarch/virt.rst
+++ b/docs/system/loongarch/virt.rst
@@ -28,6 +28,37 @@ The ``qemu-system-loongarch64`` provides emulation for virt
 machine. You can specify the machine type ``virt`` and
 cpu type ``la464``.
 
+CPU Topology
+------------
+
+The ``LA464`` type CPUs have the concept of Socket Core and Thread.
+
+For example:
+
+``-smp 1,maxcpus=M,sockets=S,cores=C,threads=T``
+
+The above parameters indicate that the machine has a maximum of ``M`` vCPUs and
+``S`` sockets, each socket has ``C`` cores, each core has ``T`` threads,
+and each thread corresponds to a vCPU.
+
+Then ``M`` ``S`` ``C`` ``T`` has the following relationship:
+
+``M = S * C * T``
+
+In the CPU topology relationship, When we know the ``socket_id`` ``core_id``
+and ``thread_id`` of the CPU, we can calculate its ``arch_id``:
+
+``arch_id = (socket_id * S) + (core_id * C) + (thread_id * T)``
+
+Similarly, when we know the ``arch_id`` of the CPU,
+we can also get its ``socket_id`` ``core_id`` and ``thread_id``:
+
+``socket_id = arch_id / (C * T)``
+
+``core_id = (arch_id / T) % C``
+
+``thread_id = arch_id % T``
+
 Boot options
 ------------
 
diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index 9a635d1d3d..2e4a71bc90 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -1143,7 +1143,6 @@ static void virt_init(MachineState *machine)
     LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(machine);
     int i;
     hwaddr base, size, ram_size = machine->ram_size;
-    const CPUArchIdList *possible_cpus;
     MachineClass *mc = MACHINE_GET_CLASS(machine);
     CPUState *cpu;
 
@@ -1163,13 +1162,27 @@ static void virt_init(MachineState *machine)
     memory_region_add_subregion(&lvms->system_iocsr, 0, &lvms->iocsr_mem);
 
     /* Init CPUs */
-    possible_cpus = mc->possible_cpu_arch_ids(machine);
-    for (i = 0; i < possible_cpus->len; i++) {
-        cpu = cpu_create(machine->cpu_type);
+    mc->possible_cpu_arch_ids(machine);
+    for (i = 0; i < machine->smp.cpus; i++) {
+        cpu = CPU(object_new(machine->cpu_type));
         cpu->cpu_index = i;
         machine->possible_cpus->cpus[i].cpu = cpu;
         lacpu = LOONGARCH_CPU(cpu);
         lacpu->phy_id = machine->possible_cpus->cpus[i].arch_id;
+        /*
+         * The cold-plug CPUs at the time of machine startup will also enter
+         * the CPU hot-plug process when it is created, but at this time,
+         * the GED device has not been created, resulting in exit in the CPU
+         * hot-plug process, which can avoid the incumbent CPU repeatedly
+         * applying for resources.
+         *
+         * The interrupt resource of the in-place CPU will be requested at
+         * function virt_irq_init().
+         *
+         * The interrupt resource of the subsequently inserted CPU will be
+         * requested in the CPU hot-plug process.
+         */
+        qdev_realize_and_unref(DEVICE(cpu), NULL, &error_fatal);
     }
     fdt_add_cpu_nodes(lvms);
     fdt_add_memory_nodes(machine);
@@ -1286,6 +1299,35 @@ static void virt_initfn(Object *obj)
     virt_flash_create(lvms);
 }
 
+static int virt_get_arch_id_from_topo(MachineState *ms, LoongArchCPUTopo *topo)
+{
+    int arch_id, sock_vcpu_num, core_vcpu_num;
+
+    /*
+     * calculate total logical cpus across socket/core/thread.
+     * For more information on how to calculate the arch_id,
+     * you can refer to the CPU Topology chapter of the
+     * docs/system/loongarch/virt.rst document.
+     */
+    sock_vcpu_num = topo->socket_id * (ms->smp.threads * ms->smp.cores);
+    core_vcpu_num = topo->core_id * ms->smp.threads;
+
+    /* get vcpu-id(logical cpu index) for this vcpu from this topology */
+    arch_id = (sock_vcpu_num + core_vcpu_num) + topo->thread_id;
+
+    assert(arch_id >= 0 && arch_id < ms->possible_cpus->len);
+
+    return arch_id;
+}
+
+static void virt_get_topo_from_index(MachineState *ms,
+                                     LoongArchCPUTopo *topo, int index)
+{
+    topo->socket_id = index / (ms->smp.cores * ms->smp.threads);
+    topo->core_id = index / ms->smp.threads % ms->smp.cores;
+    topo->thread_id = index % ms->smp.threads;
+}
+
 static bool memhp_type_supported(DeviceState *dev)
 {
     /* we only support pc dimm now */
@@ -1385,8 +1427,9 @@ static HotplugHandler *virt_get_hotplug_handler(MachineState *machine,
 
 static const CPUArchIdList *virt_possible_cpu_arch_ids(MachineState *ms)
 {
-    int n;
+    int n, arch_id;
     unsigned int max_cpus = ms->smp.max_cpus;
+    LoongArchCPUTopo topo;
 
     if (ms->possible_cpus) {
         assert(ms->possible_cpus->len == max_cpus);
@@ -1397,17 +1440,17 @@ static const CPUArchIdList *virt_possible_cpu_arch_ids(MachineState *ms)
                                   sizeof(CPUArchId) * max_cpus);
     ms->possible_cpus->len = max_cpus;
     for (n = 0; n < ms->possible_cpus->len; n++) {
+        virt_get_topo_from_index(ms, &topo, n);
+        arch_id = virt_get_arch_id_from_topo(ms, &topo);
+        ms->possible_cpus->cpus[n].vcpus_count = 1;
         ms->possible_cpus->cpus[n].type = ms->cpu_type;
-        ms->possible_cpus->cpus[n].arch_id = n;
-
+        ms->possible_cpus->cpus[n].arch_id = arch_id;
         ms->possible_cpus->cpus[n].props.has_socket_id = true;
-        ms->possible_cpus->cpus[n].props.socket_id  =
-                                   n / (ms->smp.cores * ms->smp.threads);
+        ms->possible_cpus->cpus[n].props.socket_id = topo.socket_id;
         ms->possible_cpus->cpus[n].props.has_core_id = true;
-        ms->possible_cpus->cpus[n].props.core_id =
-                                   n / ms->smp.threads % ms->smp.cores;
+        ms->possible_cpus->cpus[n].props.core_id = topo.core_id;
         ms->possible_cpus->cpus[n].props.has_thread_id = true;
-        ms->possible_cpus->cpus[n].props.thread_id = n % ms->smp.threads;
+        ms->possible_cpus->cpus[n].props.thread_id = topo.thread_id;
     }
     return ms->possible_cpus;
 }
diff --git a/target/loongarch/cpu.c b/target/loongarch/cpu.c
index 7212fb5f8f..17b65d5946 100644
--- a/target/loongarch/cpu.c
+++ b/target/loongarch/cpu.c
@@ -16,6 +16,7 @@
 #include "kvm/kvm_loongarch.h"
 #include "exec/exec-all.h"
 #include "cpu.h"
+#include "hw/qdev-properties.h"
 #include "internals.h"
 #include "fpu/softfloat-helpers.h"
 #include "cpu-csr.h"
@@ -682,6 +683,7 @@ static void loongarch_cpu_init(Object *obj)
     timer_init_ns(&cpu->timer, QEMU_CLOCK_VIRTUAL,
                   &loongarch_constant_timer_cb, cpu);
 #endif
+    cpu->phy_id = UNSET_PHY_ID;
 #endif
 }
 
@@ -780,6 +782,14 @@ static int64_t loongarch_cpu_get_arch_id(CPUState *cs)
 }
 #endif
 
+static Property loongarch_cpu_properties[] = {
+    DEFINE_PROP_INT32("socket-id", LoongArchCPU, socket_id, 0),
+    DEFINE_PROP_INT32("core-id", LoongArchCPU, core_id, 0),
+    DEFINE_PROP_INT32("thread-id", LoongArchCPU, thread_id, 0),
+    DEFINE_PROP_INT32("node-id", LoongArchCPU, node_id, CPU_UNSET_NUMA_NODE_ID),
+    DEFINE_PROP_END_OF_LIST()
+};
+
 static void loongarch_cpu_class_init(ObjectClass *c, void *data)
 {
     LoongArchCPUClass *lacc = LOONGARCH_CPU_CLASS(c);
@@ -787,6 +797,7 @@ static void loongarch_cpu_class_init(ObjectClass *c, void *data)
     DeviceClass *dc = DEVICE_CLASS(c);
     ResettableClass *rc = RESETTABLE_CLASS(c);
 
+    device_class_set_props(dc, loongarch_cpu_properties);
     device_class_set_parent_realize(dc, loongarch_cpu_realizefn,
                                     &lacc->parent_realize);
     resettable_class_set_parent_phases(rc, NULL, loongarch_cpu_reset_hold, NULL,
@@ -811,6 +822,7 @@ static void loongarch_cpu_class_init(ObjectClass *c, void *data)
 #ifdef CONFIG_TCG
     cc->tcg_ops = &loongarch_tcg_ops;
 #endif
+    dc->user_creatable = true;
 }
 
 static const gchar *loongarch32_gdb_arch_name(CPUState *cs)
diff --git a/target/loongarch/cpu.h b/target/loongarch/cpu.h
index 6c41fafb70..fb50cbbeee 100644
--- a/target/loongarch/cpu.h
+++ b/target/loongarch/cpu.h
@@ -19,6 +19,12 @@
 #include "cpu-csr.h"
 #include "cpu-qom.h"
 
+/*
+ * CPU can't have 0xFFFFFFFF physical ID, use that value to distinguish
+ * that physical ID hasn't been set yet
+ */
+#define UNSET_PHY_ID 0xFFFFFFFF
+
 #define IOCSRF_TEMP             0
 #define IOCSRF_NODECNT          1
 #define IOCSRF_MSI              2
@@ -369,6 +375,12 @@ typedef struct CPUArchState {
 #endif
 } CPULoongArchState;
 
+typedef struct LoongArchCPUTopo {
+    int32_t socket_id;  /* socket-id of this VCPU */
+    int32_t core_id;    /* core-id of this VCPU */
+    int32_t thread_id;  /* thread-id of this VCPU */
+} LoongArchCPUTopo;
+
 /**
  * LoongArchCPU:
  * @env: #CPULoongArchState
@@ -381,6 +393,10 @@ struct ArchCPU {
     CPULoongArchState env;
     QEMUTimer timer;
     uint32_t  phy_id;
+    int32_t socket_id;  /* socket-id of this VCPU */
+    int32_t core_id;    /* core-id of this VCPU */
+    int32_t thread_id;  /* thread-id of this VCPU */
+    int32_t node_id;    /* NUMA node of this VCPU */
 
     /* 'compatible' string for this CPU for Linux device trees */
     const char *dtb_compatible;
@@ -399,6 +415,7 @@ struct LoongArchCPUClass {
     CPUClass parent_class;
 
     DeviceRealize parent_realize;
+    DeviceUnrealize parent_unrealize;
     ResettablePhases parent_phases;
 };
 
-- 
2.39.3