hw/loongarch/virt: Add CPU topology support

Add topological relationships for Loongarch VCPU and initialize
topology member variables.

On LoongArch system there is socket/core/thread topo information,
physical CPU id is calculated from CPU topo, every topo sub-field is
aligned by power of 2. So it is different from logical cpu index.

Co-developed-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Bibo Mao <maobibo@loongson.cn>

hw/loongarch/virt.c

@@ -774,6 +774,48 @@ static void virt_initfn(Object *obj)
     virt_flash_create(lvms);
 }
 
+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 unsigned int topo_align_up(unsigned int count)
+{
+    g_assert(count >= 1);
+    count -= 1;
+    return BIT(count ? 32 - clz32(count) : 0);
+}
+
+/*
+ * LoongArch Reference Manual Vol1, Chapter 7.4.12 CPU Identity
+ *  For CPU architecture, bit0 .. bit8 is valid for CPU id, max cpuid is 512
+ *  However for IPI/Eiointc interrupt controller, max supported cpu id for
+ *  irq routingis 256
+ *
+ *  Here max cpu id is 256 for virt machine
+ */
+static int virt_get_arch_id_from_topo(MachineState *ms, LoongArchCPUTopo *topo)
+{
+    int arch_id, threads, cores, sockets;
+
+    threads = topo_align_up(ms->smp.threads);
+    cores = topo_align_up(ms->smp.cores);
+    sockets = topo_align_up(ms->smp.sockets);
+    if ((threads * cores * sockets) > 256) {
+        error_report("Exceeding max cpuid 256 with sockets[%d] cores[%d]"
+                     " threads[%d]", ms->smp.sockets, ms->smp.cores,
+                     ms->smp.threads);
+        exit(1);
+    }
+
+    arch_id = topo->thread_id + topo->core_id * threads;
+    arch_id += topo->socket_id * threads * cores;
+    return arch_id;
+}
+
 static bool memhp_type_supported(DeviceState *dev)
 {
     /* we only support pc dimm now */
@@ -873,8 +915,9 @@ 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);
@@ -885,17 +928,17 @@ 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].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].vcpus_count = 1;
         ms->possible_cpus->cpus[n].props.has_socket_id = true;
-        ms->possible_cpus->cpus[n].props.socket_id  =
+        ms->possible_cpus->cpus[n].props.socket_id = topo.socket_id;
-                                   n / (ms->smp.cores * ms->smp.threads);
         ms->possible_cpus->cpus[n].props.has_core_id = true;
-        ms->possible_cpus->cpus[n].props.core_id =
+        ms->possible_cpus->cpus[n].props.core_id = topo.core_id;
-                                   n / ms->smp.threads % ms->smp.cores;
         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;
 }

target/loongarch/cpu.h

@@ -393,6 +393,12 @@ 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