Re: [Qemu-ppc] [PATCH v4 0/6] spapr/xics: fix migration of older machine types

[Nikunj A Dadhania]

David Gibson <address@hidden> writes:

> On Tue, Jun 13, 2017 at 01:59:29PM +0530, Nikunj A Dadhania wrote:
>> Greg Kurz <address@hidden> writes:
>> 
>> > On Sun, 11 Jun 2017 17:38:42 +0800
>> > David Gibson <address@hidden> wrote:
>> >
>> >> On Fri, Jun 09, 2017 at 05:09:13PM +0200, Greg Kurz wrote:
>> >> > On Fri, 9 Jun 2017 20:28:32 +1000
>> >> > David Gibson <address@hidden> wrote:
>> >> >   
>> >> > > On Fri, Jun 09, 2017 at 11:36:31AM +0200, Greg Kurz wrote:  
>> >> > > > On Fri, 9 Jun 2017 12:28:13 +1000
>> >> > > > David Gibson <address@hidden> wrote:
>> >> > > >     
>> >> > > > > On Thu, Jun 08, 2017 at 03:42:32PM +0200, Greg Kurz wrote:    
>> >> > > > > > I've provided answers for all comments from the v3 review that 
>> >> > > > > > I deliberately
>> >> > > > > > don't address in v4.      
>> >> > > > > 
>> >> > > > > I've merged patches 1-4.  5 & 6 I'm still reviewing.
>> >> > > > >     
>> >> > > > 
>> >> > > > Cool. FYI, I forgot to mention that I only tested with KVM.
>> >> > > > 
>> >> > > > I'm now trying with TCG and I hit various guest crash on
>> >> > > > the destination (using your ppc-for-2.10 branch WITHOUT
>> >> > > > my patches):    
>> >> > > 
>> >> > > Drat.  What's your reproducer for this crash?
>> >> > >   
>> >> > 
>> >> > 1) start guest
>> >> > 
>> >> > qemu-system-ppc64 \
>> >> >  -nodefaults -nographic -snapshot -no-shutdown -serial mon:stdio \
>> >> >  -device virtio-net,netdev=netdev0,id=net0 \
>> >> >  -netdev 
>> >> > bridge,id=netdev0,br=virbr0,helper=/usr/libexec/qemu-bridge-helper \
>> >> >  -device virtio-blk,drive=drive0,id=blk0 \
>> >> >  -drive 
>> >> > file=/home/greg/images/sle12-sp1-ppc64le.qcow2,id=drive0,if=none \
>> >> >  -machine type=pseries,accel=tcg -cpu POWER8
>> 
>> Strangely, your command line does not have multiple threads. Need to see
>> what is the side effect of enabling MTTCG by default here.
>> 
>> >> > 
>> >> > 2) migrate
>> >> > 
>> >> > 3) destination crashes (immediately or after very short delay) or
>> >> > hangs  
>> >> 
>> >> Ok.  I'll bisect it when I can, but you might well get to it first.
>> >> 
>> >> 
>> >
>> > Heh, maybe you didn't see in my mail but I did bisect:
>> >
>> > f0b0685d6694a28c66018f438e822596243b1250 is the first bad commit
>> > commit f0b0685d6694a28c66018f438e822596243b1250
>> > Author: Nikunj A Dadhania <address@hidden>
>> > Date:   Thu Apr 27 10:48:23 2017 +0530
>> >
>> >     tcg: enable MTTCG by default for PPC64 on x86
>> 
>> Let me have a look at it.
>
> Is this crash fixed by the patch from Thomas I merged yesterday?

No, it doesn't. Moreover, in Greg's scenario there is only one cpu.

Regards,
Nikunj