[libvirt] [PATCH] qemu: lifecycle: guest get rebooted after reboot and shutdown

[Michal Privoznik]

On 17.04.2015 02:43, zhang bo wrote:
> 
> Steps:
>     1 virsh reboot guest1 --mode=acpi
>     2 virsh shutdown guest1 --mode=agent
> 
> Expected result:
>     As the SHUTDOWN job is after REBOOT, we expected the guest to be *shutoff*.
> 
> Exacted result:
>     After the 2 steps above, the guest got *rebooted*.
> 
> The reason to this problem:
>     1 in qemuDomainReboot(mode acpi), it sets priv->fakeReboot to 1.
>     2 after shutdown/reboot, qemu monitor IO trigged qemuProcessHandleShutdown(), which finds that priv->fakeReboot is 1, and reboot the guest.
> 
> Root Cause of the problem:
>     After further look into  the problem, We found that the design of acpi/agent shutdown/reboot seems a little chaotic.
>     -----------------------------------
>     sheet1 who sets fakeReboot
>     -----------------------------------
>              shutdown           reboot
>     acpi        Y(0)              Y(1)
>     agent       N                 N
>     It's apparently, *acpi-mode* jobs set fakeReboot.
>     -----------------------------------
>     sheet2 who needs to check fakeReboot(qemuProcessHandleShutdown())
>     -----------------------------------
>              shutdown           reboot
>     acpi        Y                 Y
>     agent      *Y*               *N*
>     Things become a little odd here. only agent-mode reboot doesn't check fakeReboot.
> 
>     We can tell from the above 2 sheets, that they're not consistent.
>     *Agent-mode shutdown checks fakeReboot(trigger by SHUTDOWN monitorIO event), while it didn't set it before.*
> 
>     The chaos is not caused by libvirtd, it's a systematic problem, including guest os and qemu. (guest os writes ACPI, triggers qemu, qemu then triggers libvirtd)
> 
> Solution:
>     A simple solution is to make the 1st sheet consistent to the 2nd sheet, which is:
>     -----------------------------------
>     sheet3 who should set fakeReboot:
>     -----------------------------------
>              shutdown           reboot
>     acpi        Y(0)              Y(1)
>     agent      *Y(0)*             N
>     -----------------------------------
>     we let agent-mode shutdown set fakeReboot to 0.
> 
> Signed-off-by: Zhang Bo <oscar.zhangbo at huawei.com>
> Signed-off-by: Wang Yufei <james.wangyufei at huawei.com>
> ---

Maybe I should have been more specific when requiring you to send the
patch. If you look at 'git log' you'll see this commit message diverges
from the rest. I've fixed it, ACKed and pushed.

Michal