Re: [PATCH 2/5] cpu: move Qemu[Thread|Cond] setup into common code

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On 5/30/24 12:42, Alex Bennée wrote:
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@xxxxxxxxxx>
---
  include/hw/core/cpu.h             |  4 ++++
  accel/dummy-cpus.c                |  3 ---
  accel/hvf/hvf-accel-ops.c         |  4 ----
  accel/kvm/kvm-accel-ops.c         |  3 ---
  accel/tcg/tcg-accel-ops-mttcg.c   |  4 ----
  accel/tcg/tcg-accel-ops-rr.c      | 14 +++++++-------
  hw/core/cpu-common.c              |  5 +++++
  target/i386/nvmm/nvmm-accel-ops.c |  3 ---
  target/i386/whpx/whpx-accel-ops.c |  3 ---
  9 files changed, 16 insertions(+), 27 deletions(-)

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 35d345371b..a405119eda 100644
--- a/include/hw/core/cpu.h
+++ b/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.
diff --git a/accel/dummy-cpus.c b/accel/dummy-cpus.c
index 20519f1ea4..f32d8c8dc3 100644
--- a/accel/dummy-cpus.c
+++ b/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,
diff --git a/accel/hvf/hvf-accel-ops.c b/accel/hvf/hvf-accel-ops.c
index 40d4187d9d..6f1e27ef46 100644
--- a/accel/hvf/hvf-accel-ops.c
+++ b/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,
diff --git a/accel/kvm/kvm-accel-ops.c b/accel/kvm/kvm-accel-ops.c
index 94c828ac8d..c239dfc87a 100644
--- a/accel/kvm/kvm-accel-ops.c
+++ b/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,
diff --git a/accel/tcg/tcg-accel-ops-mttcg.c b/accel/tcg/tcg-accel-ops-mttcg.c
index c552b45b8e..49814ec4af 100644
--- a/accel/tcg/tcg-accel-ops-mttcg.c
+++ b/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);
diff --git a/accel/tcg/tcg-accel-ops-rr.c b/accel/tcg/tcg-accel-ops-rr.c
index 894e73e52c..84c36c1450 100644
--- a/accel/tcg/tcg-accel-ops-rr.c
+++ b/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;
diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
index 0f0a247f56..6cfc01593a 100644
--- a/hw/core/cpu-common.c
+++ b/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);
diff --git a/target/i386/nvmm/nvmm-accel-ops.c b/target/i386/nvmm/nvmm-accel-ops.c
index 6b2bfd9b9c..0ba31201e2 100644
--- a/target/i386/nvmm/nvmm-accel-ops.c
+++ b/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,
diff --git a/target/i386/whpx/whpx-accel-ops.c b/target/i386/whpx/whpx-accel-ops.c
index 189ae0f140..1a2b4e1c43 100644
--- a/target/i386/whpx/whpx-accel-ops.c
+++ b/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,

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@xxxxxxxxxx>




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