Re: [PATCH 23/51] accel/qtest: Support qtest accelerator for Windows

[Marc-André Lureau]

Hi

On Wed, Aug 24, 2022 at 2:31 PM Bin Meng <bmeng.cn@gmail.com> wrote:

From: Xuzhou Cheng <xuzhou.cheng@windriver.com>

Currently signal SIGIPI [=SIGUSR1] is used to kick the dummy CPU
when qtest accelerator is used. However SIGUSR1 is unsupported on
Windows. To support Windows, we add a QemuSemaphore CPUState::sem
to kick the dummy CPU instead for Windows.

Signed-off-by: Xuzhou Cheng <xuzhou.cheng@windriver.com>
Signed-off-by: Bin Meng <bin.meng@windriver.com>

What if we replace signals by the semaphore on posix as well?

but lgtm,

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

 

---

 include/hw/core/cpu.h   |  1 +
 accel/dummy-cpus.c      | 14 ++++++++++++--
 softmmu/cpus.c          |  9 +++++----
 accel/meson.build       |  1 +
 accel/qtest/meson.build |  1 +
 5 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 500503da13..c564108877 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -325,6 +325,7 @@ struct CPUState {
     struct QemuThread *thread;
 #ifdef _WIN32
     HANDLE hThread;
+    QemuSemaphore sem;
 #endif
     int thread_id;
     bool running, has_waiter;
diff --git a/accel/dummy-cpus.c b/accel/dummy-cpus.c
index 10429fdfb2..d6a1b8d0a2 100644
--- a/accel/dummy-cpus.c
+++ b/accel/dummy-cpus.c
@@ -21,8 +21,6 @@
 static void *dummy_cpu_thread_fn(void *arg)
 {
     CPUState *cpu = arg;
-    sigset_t waitset;
-    int r;

     rcu_register_thread();

@@ -32,8 +30,13 @@ static void *dummy_cpu_thread_fn(void *arg)
     cpu->can_do_io = 1;
     current_cpu = cpu;

+#ifndef _WIN32
+    sigset_t waitset;
+    int r;
+
     sigemptyset(&waitset);
     sigaddset(&waitset, SIG_IPI);
+#endif

     /* signal CPU creation */
     cpu_thread_signal_created(cpu);
@@ -41,6 +44,7 @@ static void *dummy_cpu_thread_fn(void *arg)

     do {
         qemu_mutex_unlock_iothread();
+#ifndef _WIN32
         do {
             int sig;
             r = sigwait(&waitset, &sig);
@@ -49,6 +53,9 @@ static void *dummy_cpu_thread_fn(void *arg)
             perror("sigwait");
             exit(1);
         }
+#else
+        qemu_sem_wait(&cpu->sem);
+#endif
         qemu_mutex_lock_iothread();
         qemu_wait_io_event(cpu);
     } while (!cpu->unplug);
@@ -69,4 +76,7 @@ void dummy_start_vcpu_thread(CPUState *cpu)
              cpu->cpu_index);
     qemu_thread_create(cpu->thread, thread_name, dummy_cpu_thread_fn, cpu,
                        QEMU_THREAD_JOINABLE);
+#ifdef _WIN32
+    qemu_sem_init(&cpu->sem, 0);
+#endif
 }
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 23b30484b2..fd10db927a 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -437,18 +437,19 @@ void qemu_wait_io_event(CPUState *cpu)

 void cpus_kick_thread(CPUState *cpu)
 {
-#ifndef _WIN32
-    int err;
-
     if (cpu->thread_kicked) {
         return;
     }
     cpu->thread_kicked = true;
-    err = pthread_kill(cpu->thread->thread, SIG_IPI);
+
+#ifndef _WIN32
+    int err = pthread_kill(cpu->thread->thread, SIG_IPI);
     if (err && err != ESRCH) {
         fprintf(stderr, "qemu:%s: %s", __func__, strerror(err));
         exit(1);
     }
+#else
+    qemu_sem_post(&cpu->sem);
 #endif
 }

diff --git a/accel/meson.build b/accel/meson.build
index b9a963cf80..b21c85dc0a 100644
--- a/accel/meson.build
+++ b/accel/meson.build
@@ -17,4 +17,5 @@ dummy_ss.add(files(
 ))

 specific_ss.add_all(when: ['CONFIG_SOFTMMU', 'CONFIG_POSIX'], if_true: dummy_ss)
+specific_ss.add_all(when: ['CONFIG_WIN32'], if_true: dummy_ss)
 specific_ss.add_all(when: ['CONFIG_XEN'], if_true: dummy_ss)
diff --git a/accel/qtest/meson.build b/accel/qtest/meson.build
index 4c65600293..a4876fc0f2 100644
--- a/accel/qtest/meson.build
+++ b/accel/qtest/meson.build
@@ -1,2 +1,3 @@
 qtest_module_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_POSIX'],
                     if_true: files('qtest.c'))
+qtest_module_ss.add(when: ['CONFIG_WIN32'], if_true: files('qtest.c'))
--
2.34.1

--

Marc-André Lureau