From: Clement Deschamps <clement.deschamps@greensocs.com>
Date: Sun, 21 Oct 2018 14:21:03 +0000 (+0200)
Subject: icount: fix deadlock when all cpus are sleeping
X-Git-Tag: qemu-xen-4.13.0-rc1~569^2~16
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=013aabdc665e4256b38d8875a1a7b5e030ba98f1;p=qemu-xen.git

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>
---

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();
     }