Re: [Qemu-devel] QEMU postcopy-test failing on ppc64

[Greg Kurz <groug@kaod.org>]

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On Tue, 15 Nov 2016 14:48:30 +0000
Stefan Hajnoczi <stefanha@gmail.com> wrote:

> On Tue, Nov 15, 2016 at 01:58:38PM +0100, Laurent Vivier wrote:
> > 
> > 
> > On 15/11/2016 13:20, Dr. David Alan Gilbert wrote:  
> > > * Stefan Hajnoczi (stefanha@gmail.com) wrote:  
> > >> On Tue, Nov 15, 2016 at 10:09 AM, Greg Kurz <groug@kaod.org> wrote:  
> > >>> On Tue, 15 Nov 2016 10:53:35 +0100
> > >>> Laurent Vivier <lvivier@redhat.com> wrote:
> > >>>  
> > >>>> On 14/11/2016 21:52, Stefan Hajnoczi wrote:  
> > >>>>> I hit a failure running "make check" on ppc64 for the first time.  Ideas?
> > >>>>>
> > >>>>> Stefan
> > >>>>>
> > >>>>> commit 682df581c65ed2c1b9e77093e332214ecaa1ee93
> > >>>>>
> > >>>>>   GTESTER check-qtest-ppc64
> > >>>>> Memory content inconsistency at 5af4000 first_byte = 1b last_byte = 1a
> > >>>>> current = 7c hit_edge = 1
> > >>>>> Memory content inconsistency at 5af5000 first_byte = 1b last_byte = 7c
> > >>>>> current = 1b hit_edge = 1
> > >>>>> Memory content inconsistency at 5e59000 first_byte = 1b last_byte = 1b
> > >>>>> current = 1a hit_edge = 1
> > >>>>> **
> > >>>>> ERROR:tests/postcopy-test.c:345:check_guests_ram: 'bad' should be FALSE
> > >>>>> GTester: last random seed: R02S9d79166a1ca7e21940a0f4b0b1255d5b
> > >>>>>  
> > >>>>
> > >>>> Are you using KVM PR?
> > >>>>
> > >>>> it  was working fine with TCG and KVM HV.
> > >>>>
> > >>>> Apparently, USERFAULTFD doesn't work with KVM PR.
> > >>>>
> > >>>> I've already seen this kind of error with nested KVM on Power:
> > >>>> guest in guest with KVM PR in host.
> > >>>>
> > >>>> This problem was reported on IRC by Greg if I remember correctly (CC:)
> > >>>>  
> > >>>
> > >>> Yeah I hit this when running make check in a PPC64 BE guest which
> > >>> has kvm_pr loaded. I did not find time to investigate though... I've
> > >>> switched to run make check on bare metal POWER7 instead.  
> > >>
> > >> Right, it's POWER7 PPC64 BE with kvm_pr.
> > >>
> > >> If this should be fixed for QEMU 2.8 please add it to
> > >> http://qemu-project.org/Planning/2.8 and I'll track it (i.e. won't
> > >> release before it's resolved).
> > >>
> > >> If this is a known issue that will be in QEMU 2.8 please add it to
> > >> http://qemu-project.org/ChangeLog/2.8#Known_issues.  
> > > 
> > > I don't think it's new with 2.8 (Laurent?) and I think it's actually
> > > a kernel issue that needs fixing.  
> > 
> > I's not a regression and I think it's a kernel issue.
> > 
> > As it has never worked with KVM PR and can't be fixed at QEMU level, we
> > can't solve it for 2.8 (no tracking).
> > 
> > I'm going to update the know issues for 2.8.
> > [and I'm going to try to understand what really happens]  
> 
> Should the test be skipped on KVM PR?
> 
> It's a shame that make check fails.
> 

Yeah I agree this is lame but KVM PR isn't very cherished these days...

Since postcopy-test runs QEMU with -accel kvm:tcg, a possible workaround is
to kick KVM out of the environment you're running make check in.

> Stefan


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