icount: fix deadlock when all cpus are sleeping

When all cpus are sleeping (e.g in WFI), to avoid a deadlock
in the main_loop, wake it up in order to start the warp timer.

Signed-off-by: Clement Deschamps <clement.deschamps@greensocs.com>
Message-Id: <20181021142103.19014-1-clement.deschamps@greensocs.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/cpus.c b/cpus.c
index 3978f63d8f..a2b33ccb29 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1554,6 +1554,14 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg)
             atomic_mb_set(&cpu->exit_request, 0);
         }
 
+        if (use_icount && all_cpu_threads_idle()) {
+            /*
+             * When all cpus are sleeping (e.g in WFI), to avoid a deadlock
+             * in the main_loop, wake it up in order to start the warp timer.
+             */
+            qemu_notify_event();
+        }
+
         qemu_tcg_rr_wait_io_event(cpu ? cpu : first_cpu);
         deal_with_unplugged_cpus();
     }