cpu: move Qemu[Thread|Cond] setup into common code

Aside from the round robin threads this is all common code. By
moving the halt_cond setup we also no longer need hacks to work around
the race between QOM object creation and thread creation.

It is a little ugly to free stuff up for the round robin thread but
better it deal with its own specialises than making the other
accelerators jump through hoops.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-ID: <20240530194250.1801701-3-alex.bennee@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

accel/dummy-cpus.c

@@ -68,9 +68,6 @@ void dummy_start_vcpu_thread(CPUState *cpu)
 {
     char thread_name[VCPU_THREAD_NAME_SIZE];
 
-    cpu->thread = g_malloc0(sizeof(QemuThread));
-    cpu->halt_cond = g_malloc0(sizeof(QemuCond));
-    qemu_cond_init(cpu->halt_cond);
     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/DUMMY",
              cpu->cpu_index);
     qemu_thread_create(cpu->thread, thread_name, dummy_cpu_thread_fn, cpu,

accel/hvf/hvf-accel-ops.c

@@ -463,10 +463,6 @@ static void hvf_start_vcpu_thread(CPUState *cpu)
      */
     assert(hvf_enabled());
 
-    cpu->thread = g_malloc0(sizeof(QemuThread));
-    cpu->halt_cond = g_malloc0(sizeof(QemuCond));
-    qemu_cond_init(cpu->halt_cond);
-
     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/HVF",
              cpu->cpu_index);
     qemu_thread_create(cpu->thread, thread_name, hvf_cpu_thread_fn,

accel/kvm/kvm-accel-ops.c

@@ -66,9 +66,6 @@ static void kvm_start_vcpu_thread(CPUState *cpu)
 {
     char thread_name[VCPU_THREAD_NAME_SIZE];
 
-    cpu->thread = g_malloc0(sizeof(QemuThread));
-    cpu->halt_cond = g_malloc0(sizeof(QemuCond));
-    qemu_cond_init(cpu->halt_cond);
     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/KVM",
              cpu->cpu_index);
     qemu_thread_create(cpu->thread, thread_name, kvm_vcpu_thread_fn,

accel/tcg/tcg-accel-ops-mttcg.c

@@ -137,10 +137,6 @@ void mttcg_start_vcpu_thread(CPUState *cpu)
     g_assert(tcg_enabled());
     tcg_cpu_init_cflags(cpu, current_machine->smp.max_cpus > 1);
 
-    cpu->thread = g_new0(QemuThread, 1);
-    cpu->halt_cond = g_malloc0(sizeof(QemuCond));
-    qemu_cond_init(cpu->halt_cond);
-
     /* create a thread per vCPU with TCG (MTTCG) */
     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
              cpu->cpu_index);

accel/tcg/tcg-accel-ops-rr.c

@@ -317,22 +317,22 @@ void rr_start_vcpu_thread(CPUState *cpu)
     tcg_cpu_init_cflags(cpu, false);
 
     if (!single_tcg_cpu_thread) {
-        cpu->thread = g_new0(QemuThread, 1);
-        cpu->halt_cond = g_new0(QemuCond, 1);
-        qemu_cond_init(cpu->halt_cond);
+        single_tcg_halt_cond = cpu->halt_cond;
+        single_tcg_cpu_thread = cpu->thread;
 
         /* share a single thread for all cpus with TCG */
         snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "ALL CPUs/TCG");
         qemu_thread_create(cpu->thread, thread_name,
                            rr_cpu_thread_fn,
                            cpu, QEMU_THREAD_JOINABLE);
-
-        single_tcg_halt_cond = cpu->halt_cond;
-        single_tcg_cpu_thread = cpu->thread;
     } else {
-        /* we share the thread */
+        /* we share the thread, dump spare data */
+        g_free(cpu->thread);
+        qemu_cond_destroy(cpu->halt_cond);
         cpu->thread = single_tcg_cpu_thread;
         cpu->halt_cond = single_tcg_halt_cond;
+
+        /* copy the stuff done at start of rr_cpu_thread_fn */
         cpu->thread_id = first_cpu->thread_id;
         cpu->neg.can_do_io = 1;
         cpu->created = true;

hw/core/cpu-common.c

@@ -261,6 +261,11 @@ static void cpu_common_initfn(Object *obj)
     cpu->nr_threads = 1;
     cpu->cflags_next_tb = -1;
 
+    /* allocate storage for thread info, initialise condition variables */
+    cpu->thread = g_new0(QemuThread, 1);
+    cpu->halt_cond = g_new0(QemuCond, 1);
+    qemu_cond_init(cpu->halt_cond);
+
     qemu_mutex_init(&cpu->work_mutex);
     qemu_lockcnt_init(&cpu->in_ioctl_lock);
     QSIMPLEQ_INIT(&cpu->work_list);

include/hw/core/cpu.h

@@ -404,10 +404,14 @@ struct qemu_work_item;
  * @tcg_cflags: Pre-computed cflags for this cpu.
  * @nr_cores: Number of cores within this CPU package.
  * @nr_threads: Number of threads within this CPU core.
+ * @thread: Host thread details, only live once @created is #true
+ * @sem: WIN32 only semaphore used only for qtest
+ * @thread_id: native thread id of vCPU, only live once @created is #true
  * @running: #true if CPU is currently running (lockless).
  * @has_waiter: #true if a CPU is currently waiting for the cpu_exec_end;
  * valid under cpu_list_lock.
  * @created: Indicates whether the CPU thread has been successfully created.
+ * @halt_cond: condition variable sleeping threads can wait on.
  * @interrupt_request: Indicates a pending interrupt request.
  * @halted: Nonzero if the CPU is in suspended state.
  * @stop: Indicates a pending stop request.

target/i386/nvmm/nvmm-accel-ops.c

@@ -64,9 +64,6 @@ static void nvmm_start_vcpu_thread(CPUState *cpu)
 {
     char thread_name[VCPU_THREAD_NAME_SIZE];
 
-    cpu->thread = g_new0(QemuThread, 1);
-    cpu->halt_cond = g_new0(QemuCond, 1);
-    qemu_cond_init(cpu->halt_cond);
     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/NVMM",
              cpu->cpu_index);
     qemu_thread_create(cpu->thread, thread_name, qemu_nvmm_cpu_thread_fn,

target/i386/whpx/whpx-accel-ops.c

@@ -64,9 +64,6 @@ static void whpx_start_vcpu_thread(CPUState *cpu)
 {
     char thread_name[VCPU_THREAD_NAME_SIZE];
 
-    cpu->thread = g_new0(QemuThread, 1);
-    cpu->halt_cond = g_new0(QemuCond, 1);
-    qemu_cond_init(cpu->halt_cond);
     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/WHPX",
              cpu->cpu_index);
     qemu_thread_create(cpu->thread, thread_name, whpx_cpu_thread_fn,