qemu-kvm: response to SIGUSR1 to start/stop a VCPU (v2)

Commit Message

Anthony Liguori Nov. 23, 2010, 4:49 p.m. UTC

None

Patch

diff --git a/cpu-defs.h b/cpu-defs.h
index 51533c6..6434dca 100644
--- a/cpu-defs.h
+++ b/cpu-defs.h
@@ -220,6 +220,7 @@  struct KVMCPUState {
     const char *cpu_model_str;                                          \
     struct KVMState *kvm_state;                                         \
     struct kvm_run *kvm_run;                                            \
+    int sigusr1_fd;                                                     \
     int kvm_fd;                                                         \
     int kvm_vcpu_dirty;                                                 \
     struct KVMCPUState kvm_cpu_state;
diff --git a/qemu-kvm.c b/qemu-kvm.c
index 471306b..354109f 100644
--- a/qemu-kvm.c
+++ b/qemu-kvm.c
@@ -1351,6 +1351,29 @@  static void pause_all_threads(void)
     }
 }
 
+static void vcpu_stop(CPUState *env)
+{
+    if (env != cpu_single_env) {
+        env->stop = 1;
+        pthread_kill(env->kvm_cpu_state.thread, SIG_IPI);
+    } else {
+        env->stop = 0;
+        env->stopped = 1;
+        cpu_exit(env);
+    }
+
+    while (!env->stopped) {
+        qemu_cond_wait(&qemu_pause_cond);
+    }
+}
+
+static void vcpu_start(CPUState *env)
+{
+    env->stop = 0;
+    env->stopped = 0;
+    pthread_kill(env->kvm_cpu_state.thread, SIG_IPI);
+}
+
 static void resume_all_threads(void)
 {
     CPUState *penv = first_cpu;
@@ -1426,6 +1449,37 @@  static int kvm_main_loop_cpu(CPUState *env)
     return 0;
 }
 
+static __thread int sigusr1_wfd;
+
+static void on_sigusr1(int signo)
+{
+    char ch = 0;
+    if (write(sigusr1_wfd, &ch, 1) < 0) {
+        /* who cares */
+    }
+}
+
+static void sigusr1_read(void *opaque)
+{
+    CPUState *env = opaque;
+    ssize_t len;
+    int caught_signal = 0;
+
+    do {
+        char buffer[256];
+        len = read(env->sigusr1_fd, buffer, sizeof(buffer));
+        caught_signal = 1;
+    } while (len > 0);
+
+    if (caught_signal) {
+        if (env->stopped) {
+            vcpu_start(env);
+        } else {
+            vcpu_stop(env);
+        }
+    }
+}
+
 static void *ap_main_loop(void *_env)
 {
     CPUState *env = _env;
@@ -1433,10 +1487,12 @@  static void *ap_main_loop(void *_env)
 #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT
     struct ioperm_data *data = NULL;
 #endif
+    int fds[2];
 
     current_env = env;
     env->thread_id = kvm_get_thread_id();
     sigfillset(&signals);
+    sigdelset(&signals, SIGUSR1);
     sigprocmask(SIG_BLOCK, &signals, NULL);
 
 #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT
@@ -1451,6 +1507,18 @@  static void *ap_main_loop(void *_env)
     kvm_create_vcpu(env, env->cpu_index);
     setup_kernel_sigmask(env);
 
+    if (pipe(fds) == -1) {
+        /* do nothing */
+    }
+
+    fcntl(fds[0], F_SETFL, O_NONBLOCK);
+    fcntl(fds[1], F_SETFL, O_NONBLOCK);
+
+    env->sigusr1_fd = fds[0];
+    sigusr1_wfd = fds[1];
+
+    qemu_set_fd_handler2(fds[0], NULL, sigusr1_read, NULL, env);
+
     /* signal VCPU creation */
     current_env->created = 1;
     pthread_cond_signal(&qemu_vcpu_cond);
@@ -1463,6 +1531,8 @@  static void *ap_main_loop(void *_env)
     /* re-initialize cpu_single_env after re-acquiring qemu_mutex */
     cpu_single_env = env;
 
+    signal(SIGUSR1, on_sigusr1);
+
     kvm_main_loop_cpu(env);
     return NULL;
 }
diff --git a/qemu-kvm.h b/qemu-kvm.h
index 0f3fb50..3addc77 100644
--- a/qemu-kvm.h
+++ b/qemu-kvm.h
@@ -783,6 +783,7 @@  struct KVMState {
     int irqchip_in_kernel;
     int pit_in_kernel;
     int xsave, xcrs;
+    int sigusr2_fd;
 
     struct kvm_context kvm_context;
 };