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From: Laurent Vivier <lvivier@redhat.com>
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Date: Thu, 17 Nov 2016 21:22:33 +0100
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Subject: Re: [Qemu-devel] [PATCH] tests/postcopy: Use KVM on ppc64 only if
 it is KVM-HV
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To: Greg Kurz <groug@kaod.org>, Thomas Huth <thuth@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>, David Gibson <david@gibson.dropbear.id.au>, qemu-ppc@nongnu.org, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org, Andrea Arcangeli <aarcange@redhat.com>, Eric Blake <eblake@redhat.com>



On 16/11/2016 15:17, Greg Kurz wrote:
> On Wed, 16 Nov 2016 14:17:47 +0100
> Thomas Huth <thuth@redhat.com> wrote:
> 
>> On 16.11.2016 13:37, Greg Kurz wrote:
>>> On Wed, 16 Nov 2016 12:24:50 +0000
>>> "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
>>>   
>>>> * Greg Kurz (groug@kaod.org) wrote:  
>>>>> On Wed, 16 Nov 2016 09:39:31 +0100
>>>>> Thomas Huth <thuth@redhat.com> wrote:
>>>>>     
>>>>>> The ppc64 postcopy test does not work with KVM-PR, and it is also
>>>>>> causing annoying warning messages when run on a x86 host. So let's
>>>>>> use KVM here only if we know that we're running with KVM-HV (which
>>>>>> automatically also means that we're running on a ppc64 host), and
>>>>>> fall back to TCG otherwise.
>>>>>>     
[..]
> The changes to the code look ok and I prefer to spend time chasing the
> KVM PR issue rather than arguing on a comment...

For the problem itself, it seems to appear only after a
BOOK3S_INTERRUPT_SYSCALL interrupt for an KVM_EXIT_PAPR_HCALL
(H_PUT_TERM_CHAR). In this case, KVM has to exit to QEMU to manage the
output. The following interrupt is always an BOOK3S_INTERRUPT_PROGRAM
with an emulation failure.

Laurent