From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:54646)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <cohuck@redhat.com>) id 1eLv0y-0002Fg-Cy
	for qemu-devel@nongnu.org; Mon, 04 Dec 2017 12:58:49 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <cohuck@redhat.com>) id 1eLv0u-0006sU-Eg
	for qemu-devel@nongnu.org; Mon, 04 Dec 2017 12:58:48 -0500
Date: Mon, 4 Dec 2017 18:58:33 +0100
From: Cornelia Huck <cohuck@redhat.com>
Message-ID: <20171204185833.64a68453.cohuck@redhat.com>
In-Reply-To: <51a752c1-994e-e57a-8fce-1e2afcc2092c@redhat.com>
References: <20171204125505.29203-1-david@redhat.com>
	<20171204125505.29203-6-david@redhat.com>
	<20171204182244.2b789717.cohuck@redhat.com>
	<8904d9e3-990f-46e1-49d1-9d37533d025e@redhat.com>
	<20171204185352.39f2b131.cohuck@redhat.com>
	<51a752c1-994e-e57a-8fce-1e2afcc2092c@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v1 for-2.12 5/5] s390x/tcg: wire up STORE
 CHANNEL REPORT WORD
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: David Hildenbrand <david@redhat.com>
Cc: qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Christian Borntraeger <borntraeger@de.ibm.com>, Richard Henderson <rth@twiddle.net>, Alexander Graf <agraf@suse.de>, Thomas Huth <thuth@redhat.com>

On Mon, 4 Dec 2017 18:56:00 +0100
David Hildenbrand <david@redhat.com> wrote:

> On 04.12.2017 18:53, Cornelia Huck wrote:
> > On Mon, 4 Dec 2017 18:34:36 +0100
> > David Hildenbrand <david@redhat.com> wrote:
> >   
> >> On 04.12.2017 18:22, Cornelia Huck wrote:  
> >>> On Mon,  4 Dec 2017 13:55:05 +0100
> >>> David Hildenbrand <david@redhat.com> wrote:
> >>>     
> >>>> We somehow missed that, new kernels require it.    
> >>>
> >>> Why _new_ kernels? I think we have unconditionally issued stcrw since
> >>> back in 2.2?    
> >>
> >> Okay, the problem is then rather related to my setup. No ccw devices ->
> >> no stcrw.
> >>
> >> How could we ever add ccw devices to a TCG guest then?  
> > 
> > Hotplug never worked before your patches. Coldplug does not create
> > machine checks and thus does not trigger the guest to do STCRW. (Only
> > STSCH, in keeping with "all channel I/O acronyms look the same".)
> >   
> 
> But booting Fedora 26/27 without any involved hotplugs (therefore
> machine checks) triggers a STCRW.
> 
> That's how I originally found it. (I started playing with machine checks
> after I had fedora 26/27 running)
> 

Confused. Do you have a backtrace? (Guest/host)