On 10/27/2009 05:33 PM, Marcelo Tosatti wrote:
Michael reported a qemu-kvm SIGSEGV at shutdown:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x411d0940 (LWP 14446)]
0x000000000040afb4 in qemu_mod_timer (ts=0x19f0fd0,
expire_time=62275467335)
at /home/mst/scm/qemu-kvm/vl.c:1009
1009 if ((alarm_timer->flags& ALARM_FLAG_EXPIRED) == 0)
{
(gdb) l
1004 ts->next = *pt;
1005 *pt = ts;
1006
1007 /* Rearm if necessary */
1008 if (pt ==&active_timers[ts->clock->type]) {
1009 if ((alarm_timer->flags& ALARM_FLAG_EXPIRED) == 0)
{
1010 qemu_rearm_alarm_timer(alarm_timer);
1011 }
1012 /* Interrupt execution to force deadline
recalculation. */
1013 if (use_icount)
(gdb) p alarm_timer
$1 = (struct qemu_alarm_timer *) 0x0
Problem is kvm_main_loop_wait(env, 0) can process the stop request
(signalling iothread that vcpu is stopped, so its OK to exit) and
continue to kvm_cpu_exec.
Reorder kvm_main_loop_wait and kvm_cpu_exec, as suggested by Gleb.
Signed-off-by: Marcelo Tosatti<mtosatti@xxxxxxxxxx>
Reported-by: "Michael S. Tsirkin"<mst@xxxxxxxxxx>
diff --git a/qemu-kvm.c b/qemu-kvm.c
index 4c13628..809fd65 100644
--- a/qemu-kvm.c
+++ b/qemu-kvm.c
@@ -1867,8 +1867,8 @@ static int kvm_main_loop_cpu(CPUState *env)
run_cpu = !env->halted;
}
if (run_cpu) {
- kvm_main_loop_wait(env, 0);
kvm_cpu_exec(env);
+ kvm_main_loop_wait(env, 0);
} else {
kvm_main_loop_wait(env, 1000);
}
This will miss an event at the very beginning of the loop (powerdown
requested before we had a chance to spin up?). I think it should be
fine since there will be a pending signal which will break us out of
kvm_cpu_exec() before it has a chance to do anything (i.e. spin in the
guest).
So, I think it's fine, but please double check the above.
--
error compiling committee.c: too many arguments to function
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