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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 631F2C04A6B for ; Fri, 10 May 2019 11:54:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1FCFB20989 for ; Fri, 10 May 2019 11:54:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727071AbfEJLyc convert rfc822-to-8bit (ORCPT ); Fri, 10 May 2019 07:54:32 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40956 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727144AbfEJLyb (ORCPT ); Fri, 10 May 2019 07:54:31 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x4ABqF4S088742 for ; Fri, 10 May 2019 07:54:30 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 2sd77hc72f-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 10 May 2019 07:54:30 -0400 Received: from localhost by e06smtp07.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 10 May 2019 12:54:28 +0100 Received: from b06cxnps4075.portsmouth.uk.ibm.com (9.149.109.197) by e06smtp07.uk.ibm.com (192.168.101.137) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 10 May 2019 12:54:25 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4ABsNHE60293356 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 10 May 2019 11:54:23 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 885C54C04A; Fri, 10 May 2019 11:54:23 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ADD064C04E; Fri, 10 May 2019 11:54:22 +0000 (GMT) Received: from oc2783563651 (unknown [9.145.163.252]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 10 May 2019 11:54:22 +0000 (GMT) Date: Fri, 10 May 2019 13:54:21 +0200 From: Halil Pasic To: Pierre Morel Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, Cornelia Huck , Martin Schwidefsky , Sebastian Ott , virtualization@lists.linux-foundation.org, "Michael S. Tsirkin" , Christoph Hellwig , Thomas Huth , Christian Borntraeger , Viktor Mihajlovski , Vasily Gorbik , Janosch Frank , Claudio Imbrenda , Farhan Ali , Eric Farman Subject: Re: [PATCH 08/10] virtio/s390: add indirection to indicators access In-Reply-To: References: <20190426183245.37939-1-pasic@linux.ibm.com> <20190426183245.37939-9-pasic@linux.ibm.com> <716d47ca-016f-e8f4-6d78-7746a7d9f6ba@linux.ibm.com> <20190509202600.4fd6aebe.pasic@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-TM-AS-GCONF: 00 x-cbid: 19051011-0028-0000-0000-0000036C5064 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19051011-0029-0000-0000-0000242BD606 Message-Id: <20190510135421.5363f14a.pasic@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-09_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905100085 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 10 May 2019 09:43:08 +0200 Pierre Morel wrote: > On 09/05/2019 20:26, Halil Pasic wrote: > > On Thu, 9 May 2019 14:01:01 +0200 > > Pierre Morel wrote: > > > >> On 08/05/2019 16:31, Pierre Morel wrote: > >>> On 26/04/2019 20:32, Halil Pasic wrote: > >>>> This will come in handy soon when we pull out the indicators from > >>>> virtio_ccw_device to a memory area that is shared with the hypervisor > >>>> (in particular for protected virtualization guests). > >>>> > >>>> Signed-off-by: Halil Pasic > >>>> --- > >>>>   drivers/s390/virtio/virtio_ccw.c | 40 > >>>> +++++++++++++++++++++++++--------------- > >>>>   1 file changed, 25 insertions(+), 15 deletions(-) > >>>> > >>>> diff --git a/drivers/s390/virtio/virtio_ccw.c > >>>> b/drivers/s390/virtio/virtio_ccw.c > >>>> index bb7a92316fc8..1f3e7d56924f 100644 > >>>> --- a/drivers/s390/virtio/virtio_ccw.c > >>>> +++ b/drivers/s390/virtio/virtio_ccw.c > >>>> @@ -68,6 +68,16 @@ struct virtio_ccw_device { > >>>>       void *airq_info; > >>>>   }; > >>>> +static inline unsigned long *indicators(struct virtio_ccw_device *vcdev) > >>>> +{ > >>>> +    return &vcdev->indicators; > >>>> +} > >>>> + > >>>> +static inline unsigned long *indicators2(struct virtio_ccw_device > >>>> *vcdev) > >>>> +{ > >>>> +    return &vcdev->indicators2; > >>>> +} > >>>> + > >>>>   struct vq_info_block_legacy { > >>>>       __u64 queue; > >>>>       __u32 align; > >>>> @@ -337,17 +347,17 @@ static void virtio_ccw_drop_indicator(struct > >>>> virtio_ccw_device *vcdev, > >>>>           ccw->cda = (__u32)(unsigned long) thinint_area; > >>>>       } else { > >>>>           /* payload is the address of the indicators */ > >>>> -        indicatorp = kmalloc(sizeof(&vcdev->indicators), > >>>> +        indicatorp = kmalloc(sizeof(indicators(vcdev)), > >>>>                        GFP_DMA | GFP_KERNEL); > >>>>           if (!indicatorp) > >>>>               return; > >>>>           *indicatorp = 0; > >>>>           ccw->cmd_code = CCW_CMD_SET_IND; > >>>> -        ccw->count = sizeof(&vcdev->indicators); > >>>> +        ccw->count = sizeof(indicators(vcdev)); > >>> > >>> This looks strange to me. Was already weird before. > >>> Lucky we are indicators are long... > >>> may be just sizeof(long) > >> > > > > I'm not sure I understand where are you coming from... > > > > With CCW_CMD_SET_IND we tell the hypervisor the guest physical address > > at which the so called classic indicators. There is a comment that > > makes this obvious. The argument of the sizeof was and remained a > > pointer type. AFAIU this is what bothers you. > >> > >> AFAIK the size of the indicators (AIV/AIS) is not restricted by the > >> architecture. > > > > The size of vcdev->indicators is restricted or defined by the virtio > > specification. Please have a look at '4.3.2.6.1 Setting Up Classic Queue > > Indicators' here: > > https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html#x1-1630002 > > > > Since with Linux on s390 only 64 bit is supported, both the sizes are in > > line with the specification. Using u64 would semantically match the spec > > better, modulo pre virtio 1.0 which ain't specified. I did not want to > > do changes that are not necessary for what I'm trying to accomplish. If > > we want we can change these to u64 with a patch on top. > > I mean you are changing these line already, so why not doing it right > while at it? > This patch is about adding the indirection so we can move the member painlessly. Mixing in different stuff would be a bad practice. BTW I just explained that it ain't wrong, so I really do not understand what do you mean by 'why not doing it right'. Can you please explain? Did you agree with the rest of my comment? I mean there was more to it. Regards, Halil