[v3,31/54] accel/qtest: Implement a portable qtest accelerator

Commit Message

Bin Meng Sept. 25, 2022, 11:30 a.m. UTC

From: Xuzhou Cheng <[e-mail]>

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.

As a result of this, the POSIX implementation via signal is no
longer needed and can use the same path as Windows.

Signed-off-by: Xuzhou Cheng <[e-mail]>
Signed-off-by: Bin Meng <[e-mail]>
Reviewed-by: Marc-André Lureau <[e-mail]>
---

(no changes since v2)

Changes in v2:
- Replace signal by the semaphore on posix too

 include/hw/core/cpu.h   |  1 +
 accel/dummy-cpus.c      | 15 ++-------------
 softmmu/cpus.c          | 10 +---------
 accel/meson.build       |  1 +
 accel/qtest/meson.build |  1 +
 5 files changed, 6 insertions(+), 22 deletions(-)

Patch

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 500503da13..2f46c37dc1 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -326,6 +326,7 @@  struct CPUState {
 #ifdef _WIN32
     HANDLE hThread;
 #endif
+    QemuSemaphore sem;
     int thread_id;
     bool running, has_waiter;
     struct QemuCond *halt_cond;
diff --git a/accel/dummy-cpus.c b/accel/dummy-cpus.c
index 10429fdfb2..3769d3db0a 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();
 
@@ -32,23 +30,13 @@  static void *dummy_cpu_thread_fn(void *arg)
     cpu->can_do_io = 1;
     current_cpu = cpu;
 
-    sigemptyset(&waitset);
-    sigaddset(&waitset, SIG_IPI);
-
     /* signal CPU creation */
     cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
         qemu_mutex_unlock_iothread();
-        do {
-            int sig;
-            r = sigwait(&waitset, &sig);
-        } while (r == -1 && (errno == EAGAIN || errno == EINTR));
-        if (r == -1) {
-            perror("sigwait");
-            exit(1);
-        }
+        qemu_sem_wait(&cpu->sem);
         qemu_mutex_lock_iothread();
         qemu_wait_io_event(cpu);
     } while (!cpu->unplug);
@@ -67,6 +55,7 @@  void dummy_start_vcpu_thread(CPUState *cpu)
     qemu_cond_init(cpu->halt_cond);
     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/DUMMY",
              cpu->cpu_index);
+    qemu_sem_init(&cpu->sem, 0);
     qemu_thread_create(cpu->thread, thread_name, dummy_cpu_thread_fn, cpu,
                        QEMU_THREAD_JOINABLE);
 }
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 23b30484b2..2a992d0d5f 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -437,19 +437,11 @@  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);
-    if (err && err != ESRCH) {
-        fprintf(stderr, "qemu:%s: %s", __func__, strerror(err));
-        exit(1);
-    }
-#endif
+    qemu_sem_post(&cpu->sem);
 }
 
 void qemu_cpu_kick(CPUState *cpu)
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'))