On Mon, 4 Dec 2017 19:37:26 +0100 David Hildenbrand <da...@redhat.com> wrote:
> On 04.12.2017 18:58, Cornelia Huck wrote: > > On Mon, 4 Dec 2017 18:56:00 +0100 > > David Hildenbrand <da...@redhat.com> wrote: > > > >> On 04.12.2017 18:53, Cornelia Huck wrote: > >>> On Mon, 4 Dec 2017 18:34:36 +0100 > >>> David Hildenbrand <da...@redhat.com> wrote: > >>> > >>>> On 04.12.2017 18:22, Cornelia Huck wrote: > >>>>> On Mon, 4 Dec 2017 13:55:05 +0100 > >>>>> David Hildenbrand <da...@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) > > > > 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." > Yeah, let's do that.
