From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37037) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eLvcX-0004Rs-93 for qemu-devel@nongnu.org; Mon, 04 Dec 2017 13:37:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eLvcQ-0000CW-Ql for qemu-devel@nongnu.org; Mon, 04 Dec 2017 13:37:34 -0500 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> <20171204185833.64a68453.cohuck@redhat.com> From: David Hildenbrand Message-ID: Date: Mon, 4 Dec 2017 19:37:26 +0100 MIME-Version: 1.0 In-Reply-To: <20171204185833.64a68453.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US 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: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck Cc: qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Christian Borntraeger , Richard Henderson , Alexander Graf , Thomas Huth On 04.12.2017 18:58, Cornelia Huck wrote: > On Mon, 4 Dec 2017 18:56:00 +0100 > David Hildenbrand wrote: > >> On 04.12.2017 18:53, Cornelia Huck wrote: >>> On Mon, 4 Dec 2017 18:34:36 +0100 >>> David Hildenbrand wrote: >>> >>>> On 04.12.2017 18:22, Cornelia Huck wrote: >>>>> On Mon, 4 Dec 2017 13:55:05 +0100 >>>>> David Hildenbrand 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) > Unfortunately not. Strange, I just tried to reproduce but can't trigger it. Maybe aside effect from the other BUGs I have been fixing :) So I'll just rephrase this to "CRW machine check handling requires STCRW." -- Thanks, David / dhildenb