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Re: [Qemu-devel] Weird thing happen when the VM is stop! (0.12.3)
From: |
Jun Koi |
Subject: |
Re: [Qemu-devel] Weird thing happen when the VM is stop! (0.12.3) |
Date: |
Sat, 10 Apr 2010 01:12:27 +0900 |
On Fri, Apr 9, 2010 at 10:20 PM, Luiz Capitulino <address@hidden> wrote:
> On Fri, 9 Apr 2010 18:32:21 +0900
> Jun Koi <address@hidden> wrote:
>
>> Hi,
>>
>> I found something very funny happening with 0.12.3: it seems the VM is
>> still running even I already stopped it.
>>
>> Here is how I verified that: Boot any OS (I checked with Windows XP
>> and Ubuntu) with 0.12.3, and stop it any time after it booted up. Use
>> "stop" command on monitor interface.
>>
>> Now the VM stops. Then in the same monitor interface, run "info
>> registers" again and again. You can see that the value of EIP and
>> EFLAGS still change once in a while. This should not happen, becaues
>> the VM already stopped.
>>
>> I checked, and dont see this problem with 0.11.1. And this doesnt
>> happen with the latest code in the git tree, either.
>>
>> Any idea on why this happens???
>
> Can you try commit 55274a305 ? If it fixes the problem we need it
> in stable, if it doesn't you can try to find the fix by using git bisect.
>
This hint makes sense, but the point is that I tried with some commits
before that 55274a305, and didnt see the problem. Still I am not sure
the problem is already fixed before 55274a305, or I am just unlucky
enough not see the problem when testing.
After bisecting, I can say that the culprit is the below patch, from Marcelo.
Now I am wondering if the above commit 55274a305 of Paolo Bonzini
fixed the bug, or other commit before that?? We should find the
correct fix, and port it to 0.12.4.
Thanks,
J
commit 535d2eb34a0f1908dc694c51ce8d4ec6dccc7807
Author: Marcelo Tosatti <address@hidden>
Date: Tue Feb 9 12:49:04 2010 -0200
iothread: fix vcpu stop with smp tcg
Round robin vcpus in tcg_cpu_next even if the vm stopped. This
allows all cpus to enter stopped state.
Signed-off-by: Marcelo Tosatti <address@hidden>
Signed-off-by: Anthony Liguori <address@hidden>
(cherry picked from commit c37cc7b072fa4ca8d8d21ac31d26baff5f47f9f9)
diff --git a/vl.c b/vl.c
index 007709a..3b5a8e0 100644
--- a/vl.c
+++ b/vl.c
@@ -4042,14 +4042,15 @@ static void tcg_cpu_exec(void)
for (; next_cpu != NULL; next_cpu = next_cpu->next_cpu) {
CPUState *env = cur_cpu = next_cpu;
- if (!vm_running)
- break;
if (timer_alarm_pending) {
timer_alarm_pending = 0;
break;
}
if (cpu_can_run(env))
ret = qemu_cpu_exec(env);
+ else if (env->stop)
+ break;
+
if (ret == EXCP_DEBUG) {
gdb_set_stop_cpu(env);
debug_requested = 1;