From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C186C47247 for ; Fri, 8 May 2020 10:47:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1445208DB for ; Fri, 8 May 2020 10:47:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SJLGDbAl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726950AbgEHKrg (ORCPT ); Fri, 8 May 2020 06:47:36 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:39044 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726751AbgEHKrf (ORCPT ); Fri, 8 May 2020 06:47:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588934854; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SEDOfW/qGS5s4maaqBjklYq821EFGHUya19S5KaYYO0=; b=SJLGDbAlzbnLkLaKQx8QytJhov76Bo+KxOXQ8hvwmqvWZ/iCHwNxbwSgHK/NsTTqERStnn F5uo9nhulyOkBzduL0HuZAZUPzDgaJinjtfXUdM8svGgasBlcyl6I8yvEm4m3L10jlp9Bb RbVVY5EBreURW/NV0aG+Xid7tNHl5RM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-484-dJ3cNptYMiC7WzVScgx75w-1; Fri, 08 May 2020 06:47:30 -0400 X-MC-Unique: dJ3cNptYMiC7WzVScgx75w-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7A9E680058A; Fri, 8 May 2020 10:47:29 +0000 (UTC) Received: from gondolin (ovpn-112-144.ams2.redhat.com [10.36.112.144]) by smtp.corp.redhat.com (Postfix) with ESMTP id 12DD510013BD; Fri, 8 May 2020 10:47:27 +0000 (UTC) Date: Fri, 8 May 2020 12:47:25 +0200 From: Cornelia Huck To: Jared Rossi Cc: Eric Farman , Halil Pasic , linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org 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> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@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.