[Qemu-devel] [PATCH] fix 100% cpu utilization when cpu is stopped (was Re: d6f4ade214a9f74dca9495b83a24ff9c113e4f9a)

[Paolo Bonzini <pbonzini@redhat.com>]

On 04/05/2010 03:51 PM, malc wrote:
> Hello,
>
> d6f4ade214a9f74dca9495b83a24ff9c113e4f9a: disentangle tcg and deadline calculation
> introduces following regression(s):
>
> 100% cpu utilization when QEMU is invoked like:
> qemu -S -s ...
>
> ditto when gdb takes control over the session via gdb-stub
> (i.e. the breakpoint is hit or C-c is pressed inside gdb to
>   interrupt the attached qemu instance)

The bug is that env->stopped is not really as comprehensive as it seems 
to be (and cpu_has_work thinks); it is only valid with iothread 
basically, and even then it is cleared by reset and it is not set when 
starting qemu with -S.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/cpus.c b/cpus.c
index a2e0642..0debe77 100644
--- a/cpus.c
+++ b/cpus.c
@@ -100,9 +100,7 @@ static int cpu_can_run(CPUState *env)
  {
      if (env->stop)
          return 0;
-    if (env->stopped)
-        return 0;
-    if (!vm_running)
+    if (env->stopped || !vm_running)
          return 0;
      return 1;
  }
@@ -111,7 +109,7 @@ static int cpu_has_work(CPUState *env)
  {
      if (env->stop)
          return 1;
-    if (env->stopped)
+    if (env->stopped || !vm_running)
          return 0;
      if (!env->halted)
          return 1;