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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 6C938C4321A for ; Tue, 11 Jun 2019 19:38:24 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 48E952173C for ; Tue, 11 Jun 2019 19:38:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 48E952173C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55092 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hamb9-0003PT-Fb for qemu-devel@archiver.kernel.org; Tue, 11 Jun 2019 15:38:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36788) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hama9-0002aj-PH for qemu-devel@nongnu.org; Tue, 11 Jun 2019 15:37:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hama8-0005xA-JJ for qemu-devel@nongnu.org; Tue, 11 Jun 2019 15:37:21 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:42140) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hama8-0005wX-7B for qemu-devel@nongnu.org; Tue, 11 Jun 2019 15:37:20 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5BJb65T111169 for ; Tue, 11 Jun 2019 15:37:19 -0400 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0a-001b2d01.pphosted.com with ESMTP id 2t2htnj61r-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 11 Jun 2019 15:37:18 -0400 Received: from localhost by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 11 Jun 2019 20:37:15 +0100 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08025.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5BJbDvi35389874 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 11 Jun 2019 19:37:13 GMT Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9961A7805F; Tue, 11 Jun 2019 19:37:13 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3A3D478063; Tue, 11 Jun 2019 19:37:13 +0000 (GMT) Received: from [9.56.58.18] (unknown [9.56.58.18]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Tue, 11 Jun 2019 19:37:13 +0000 (GMT) To: Cornelia Huck References: <20190607145353.2052-1-cohuck@redhat.com> <77395432-9619-1fee-4aeb-5685b8aa9be3@linux.ibm.com> <20190607170907.1d682513.cohuck@redhat.com> <20190611133716.427269b5.cohuck@redhat.com> From: Farhan Ali Date: Tue, 11 Jun 2019 15:37:12 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20190611133716.427269b5.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19061119-0012-0000-0000-000017434356 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011247; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000286; SDB=6.01216565; UDB=6.00639666; IPR=6.00997664; MB=3.00027268; MTD=3.00000008; XFM=3.00000015; UTC=2019-06-11 19:37:16 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19061119-0013-0000-0000-000057A85D1E Message-Id: <298b9c16-e4b1-16e7-6fe6-671d482c65d8@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-06-11_10:, , 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-1906110126 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 148.163.156.1 Subject: Re: [Qemu-devel] [PATCH v5] vfio-ccw: support async command subregion X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Halil Pasic , Eric Farman , qemu-s390x@nongnu.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 06/11/2019 07:37 AM, Cornelia Huck wrote: > On Fri, 7 Jun 2019 11:19:09 -0400 > Farhan Ali wrote: > >> On 06/07/2019 11:09 AM, Cornelia Huck wrote: >>> On Fri, 7 Jun 2019 11:02:36 -0400 >>> Farhan Ali wrote: >>> >>>> On 06/07/2019 10:53 AM, Cornelia Huck wrote: > >>>>> diff --git a/hw/s390x/css.c b/hw/s390x/css.c >>>>> index ad310b9f94bc..b92395f165e6 100644 >>>>> --- a/hw/s390x/css.c >>>>> +++ b/hw/s390x/css.c >>>>> @@ -22,6 +22,7 @@ >>>>> #include "trace.h" >>>>> #include "hw/s390x/s390_flic.h" >>>>> #include "hw/s390x/s390-virtio-ccw.h" >>>>> +#include "hw/s390x/s390-ccw.h" >>>>> >>>>> typedef struct CrwContainer { >>>>> CRW crw; >>>>> @@ -1205,6 +1206,26 @@ static void sch_handle_start_func_virtual(SubchDev *sch) >>>>> >>>>> } >>>>> >>>>> +static void sch_handle_halt_func_passthrough(SubchDev *sch) >>>>> +{ >>>>> + int ret; >>>>> + >>>>> + ret = s390_ccw_halt(sch); >>>>> + if (ret == -ENOSYS) { >>>>> + sch_handle_halt_func(sch); >>>>> + } >>>>> +} >>>>> + >>>>> +static void sch_handle_clear_func_passthrough(SubchDev *sch) >>>>> +{ >>>>> + int ret; >>>>> + >>>>> + ret = s390_ccw_clear(sch); >>>>> + if (ret == -ENOSYS) { >>>>> + sch_handle_clear_func(sch); >>>>> + } >>>>> +} >>>>> + >>>> >>>> do we need an extra s390_ccw_clear/halt functions? can't we just call >>>> cdc->clear/halt in the passthrough functions? >>> >>> I mostly added them for symmetry reasons... we still need to check for >>> presence of the callback in any case, though. >>> >>> (vfio is not always built, e.g. on windows or os x.) >> >> >> right, but if we are calling do_subchannel_work_passthrough, then we >> know for sure we are building the S390CCWDevice which is the vfio >> device, no? >> >> So we could just add checks for callbacks in >> sch_handle_clear/halt_func_passthrough, no? >> >> I would even like to get rid of the s390_ccw_cmd_request if we can, but >> that is out of scope for this patch. :) > > Ok, I just walked through various source files (some of which are a bit > confusingly named) again and now I understand again why it was done > that way in the first place. > > - hw/s390x/s390-ccw.c provides some interfaces for pass-through ccw > devices. It is built unconditionally, and its interfaces are called > unconditionally from the css code. > It also provides a device class where code can hook up callbacks. > - hw/vfio/ccw.c (which is not built for !KVM) actually hooks up > callbacks in that device class. > > So, s390-ccw.c (not to be confused with ccw-device.c...) provides a > layer that makes it possible to call things unconditionally, regardless > whether we have vfio-ccw available or not. Not that the code ends up > being called without vfio-ccw support; but the class indirection > enables the code to be built. > Okay, now I get it. Thanks for the explanation, I really do appreciate it! :) > There's possibly a way to make this work without the class indirection > as well, but I think we'd end up doing code juggling before ending up > with something that's not really nicer than the code we have now. > Therefore, I'd prefer to keep the class handling and hook up the > halt/clear callbacks there as well. > > Yeah I agree, given the constraints I don't think any code juggling would look any prettier. Thanks Farhan