From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:38874 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726797AbgEHKre (ORCPT ); Fri, 8 May 2020 06:47:34 -0400 Date: Fri, 8 May 2020 12:47:25 +0200 From: Cornelia Huck Subject: Re: [PATCH v4 1/1] vfio-ccw: Enable transparent CCW IPL from DASD Message-ID: <20200508124725.58fb985a.cohuck@redhat.com> In-Reply-To: <20200506212440.31323-2-jrossi@linux.ibm.com> References: <20200506212440.31323-1-jrossi@linux.ibm.com> <20200506212440.31323-2-jrossi@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Jared Rossi Cc: Eric Farman , Halil Pasic , linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, 6 May 2020 17:24:40 -0400 Jared Rossi wrote: > Remove the explicit prefetch check when using vfio-ccw devices. > This check does not trigger in practice as all Linux channel programs > are intended to use prefetch. > > It is expected that all ORBs issued by Linux will request prefetch. > Although non-prefetching ORBs are not rejected, they will prefetch > nonetheless. A warning is issued up to once per 5 seconds when a > forced prefetch occurs. > > A non-prefetch ORB does not necessarily result in an error, however > frequent encounters with non-prefetch ORBs indicate that channel > programs are being executed in a way that is inconsistent with what > the guest is requesting. While there is currently no known case of an > error caused by forced prefetch, it is possible in theory that forced > prefetch could result in an error if applied to a channel program that > is dependent on non-prefetch. > > Signed-off-by: Jared Rossi > --- > Documentation/s390/vfio-ccw.rst | 6 ++++++ > drivers/s390/cio/vfio_ccw_cp.c | 19 ++++++++++++------- > 2 files changed, 18 insertions(+), 7 deletions(-) > Thanks, applied.