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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id C5EE2C433EF for ; Tue, 3 May 2022 14:52:02 +0000 (UTC) Received: from localhost ([::1]:48822 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nltsf-0002hR-Rv for qemu-devel@archiver.kernel.org; Tue, 03 May 2022 10:52:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48612) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nltrK-000164-5W; Tue, 03 May 2022 10:50:38 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:33726) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nltrH-00063E-Hf; Tue, 03 May 2022 10:50:37 -0400 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 243Dh2ho002072; Tue, 3 May 2022 14:50:30 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : from : subject : to : cc : references : in-reply-to : content-type : content-transfer-encoding : mime-version; s=pp1; bh=UwgTh5QOcMbfmV9n+HGuKkuoRjZtv3LKIv4WmbpVBD8=; b=ci7Fo6y2ZPrUSCpE0CehUCAGDNdW7B910moh4AwuU00n8pXuYi0cj6oaPlyLS27vb2XT y8qq025W54XVft280SCTepbxoM1W50SMV/ZmFmjnBvDSOKc56hfGZVgjuMw5+Vn/1DOU fn8Hwhdg+Iw//o3PgWC57FmsOSI9Zzp5hmMgrZvN5YnbMd/clvncWuOig4qsqPV5ZSfx Mhe+nLu1hdjBLIhNGYSFjUkG+nHqxGTNEWp64K1cT+TpSRCceYGHwFNfbnor1bhOiHfK 4BHjiydyt3aTvHX0nhqod9h4a7gKAtLGoD9dhBZJ0LMe7U+Jy59KoHng5m909R/eq9od sQ== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3fu2v6mjrt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 03 May 2022 14:50:30 +0000 Received: from m0098394.ppops.net (m0098394.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 243EncdE010633; Tue, 3 May 2022 14:50:29 GMT Received: from ppma04fra.de.ibm.com (6a.4a.5195.ip4.static.sl-reverse.com [149.81.74.106]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3fu2v6mjqx-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 03 May 2022 14:50:29 +0000 Received: from pps.filterd (ppma04fra.de.ibm.com [127.0.0.1]) by ppma04fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 243EmEGh004610; Tue, 3 May 2022 14:50:26 GMT Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by ppma04fra.de.ibm.com with ESMTP id 3frvr8uf70-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 03 May 2022 14:50:26 +0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 243EoNWE40173992 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 3 May 2022 14:50:23 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6815B42045; Tue, 3 May 2022 14:50:23 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A66564203F; Tue, 3 May 2022 14:50:22 +0000 (GMT) Received: from [9.171.15.97] (unknown [9.171.15.97]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 3 May 2022 14:50:22 +0000 (GMT) Message-ID: Date: Tue, 3 May 2022 16:53:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 From: Pierre Morel Subject: Re: [PATCH v5 7/9] s390x/pci: enable adapter event notification for interpreted devices To: Matthew Rosato , Niklas Schnelle , qemu-s390x@nongnu.org, alex.williamson@redhat.com Cc: cohuck@redhat.com, thuth@redhat.com, farman@linux.ibm.com, richard.henderson@linaro.org, david@redhat.com, pasic@linux.ibm.com, borntraeger@linux.ibm.com, mst@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org, kvm@vger.kernel.org References: <20220404181726.60291-1-mjrosato@linux.ibm.com> <20220404181726.60291-8-mjrosato@linux.ibm.com> <31b5f911-0e1f-ba3c-94f2-1947d5b16057@linux.ibm.com> <9a171204-6d71-ee1d-d8bd-cd4eac91c3d5@linux.ibm.com> <2df134498bf60e4878bdb362a28c56ec32d902f8.camel@linux.ibm.com> <8ad9f2c8-9fb8-cb47-fd1e-f9a33eced548@linux.ibm.com> Content-Language: en-US In-Reply-To: <8ad9f2c8-9fb8-cb47-fd1e-f9a33eced548@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: f9dffIdHfqUMsOPAG0OREyI-oZgCpAZa X-Proofpoint-GUID: wFTMgtS3unEA3n949KIqy-eadB9kmS56 Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-03_06,2022-05-02_03,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 mlxlogscore=999 adultscore=0 priorityscore=1501 suspectscore=0 bulkscore=0 spamscore=0 lowpriorityscore=0 mlxscore=0 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2205030104 Received-SPF: pass client-ip=148.163.156.1; envelope-from=pmorel@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 5/2/22 21:57, Matthew Rosato wrote: > On 5/2/22 7:30 AM, Pierre Morel wrote: >> >> >> On 5/2/22 11:19, Niklas Schnelle wrote: >>> On Mon, 2022-05-02 at 09:48 +0200, Pierre Morel wrote: >>>> >>>> On 4/22/22 14:10, Matthew Rosato wrote: >>>>> On 4/22/22 5:39 AM, Pierre Morel wrote: >>>>>> >>>>>> On 4/4/22 20:17, Matthew Rosato wrote: >>>>>>> Use the associated kvm ioctl operation to enable adapter event >>>>>>> notification >>>>>>> and forwarding for devices when requested.  This feature will be >>>>>>> set up >>>>>>> with or without firmware assist based upon the 'forwarding_assist' >>>>>>> setting. >>>>>>> >>>>>>> Signed-off-by: Matthew Rosato >>>>>>> --- >>>>>>>    hw/s390x/s390-pci-bus.c         | 20 ++++++++++++++--- >>>>>>>    hw/s390x/s390-pci-inst.c        | 40 >>>>>>> +++++++++++++++++++++++++++++++-- >>>>>>>    hw/s390x/s390-pci-kvm.c         | 30 +++++++++++++++++++++++++ >>>>>>>    include/hw/s390x/s390-pci-bus.h |  1 + >>>>>>>    include/hw/s390x/s390-pci-kvm.h | 14 ++++++++++++ >>>>>>>    5 files changed, 100 insertions(+), 5 deletions(-) >>>>>>> >>>>>>> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c >>>>>>> index 9c02d31250..47918d2ce9 100644 >>>>>>> --- a/hw/s390x/s390-pci-bus.c >>>>>>> +++ b/hw/s390x/s390-pci-bus.c >>>>>>> @@ -190,7 +190,10 @@ void s390_pci_sclp_deconfigure(SCCB *sccb) >>>>>>>            rc = SCLP_RC_NO_ACTION_REQUIRED; >>>>>>>            break; >>>>>>>        default: >>>>>>> -        if (pbdev->summary_ind) { >>>>>>> +        if (pbdev->interp && (pbdev->fh & FH_MASK_ENABLE)) { >>>>>>> +            /* Interpreted devices were using interrupt >>>>>>> forwarding */ >>>>>>> +            s390_pci_kvm_aif_disable(pbdev); >>>>>> >>>>>> Same remark as for the kernel part. >>>>>> The VFIO device is already initialized and the action is on this >>>>>> device, Shouldn't we use the VFIO device interface instead of the KVM >>>>>> interface? >>>>>> >>>>> >>>>> I don't necessarily disagree, but in v3 of the kernel series I was >>>>> told >>>>> not to use VFIO ioctls to accomplish tasks that are unique to KVM >>>>> (e.g. >>>>> AEN interpretation) and to instead use a KVM ioctl. >>>>> >>>>> VFIO_DEVICE_SET_IRQS won't work as-is for reasons described in the >>>>> kernel series (e.g. we don't see any of the config space notifiers >>>>> because of instruction interpretation) -- as far as I can figure we >>>>> could add our own s390 code to QEMU to issue VFIO_DEVICE_SET_IRQS >>>>> directly for an interpreted device, but I think would also need >>>>> s390-specific changes to VFIO_DEVICE_SET_IRQS accommodate this (e.g. >>>>> maybe something like a VFIO_IRQ_SET_DATA_S390AEN where we can then >>>>> specify the aen information in vfio_irq_set.data -- or something >>>>> else I >>>> >>>> Hi, >>>> >>>> yes this in VFIO_DEVICE_SET_IRQS is what I think should be done. >>>> >>>>> haven't though of yet) -- I can try to look at this some more and >>>>> see if >>>>> I get a good idea. >>>> >>>> >>>> I understood that the demand was concerning the IOMMU but I may be >>>> wrong. > > The IOMMU was an issue, but the request to move the ioctl out of vfio to > kvm was specifically because these ioctl operations were only relevant > for VMs and are not applicable to vfio uses cases outside of > virtualization. > > https://lore.kernel.org/kvm/20220208185141.GH4160@nvidia.com/ I absolutely agree that KVM specific handling should go through KVM fd. But as I say here under, AEN is not KVM specific but device specific. Instruction interpretation is KVM specific. see later---v > >>>> For my opinion, the handling of AEN is not specific to KVM but specific >>>> to the device, for example the code should be the same if Z ever decide >>>> to use XEN or another hypervizor, except for the GISA part but this >>>> part >>>> is already implemented in KVM in a way it can be used from a device >>>> like >>>> in VFIO AP. > > > Fundamentally, these operations are valid only when you have _both_ a > virtual machine and vfio device.  (Yes, you could swap in a new > hypervisor with a new GISA implementation, but at the end of it the > hypervisor must still provide the GISA designation for this to work) > > If fh lookup is a concern, one idea that Jason floated was passing the > vfio device fd as an argument to the kvm ioctl (so pass this down on a > kvm ioctl from userspace instead of a fh) and then using a new vfio > external API to get the relevant device from the provided fd. > > https://lore.kernel.org/kvm/20220208195117.GI4160@nvidia.com/ ^------ This looks like a wrong architecture to me. If something is used to virtualize the I/O of a device it should go through the device VFIO fd. If we need a new VFIO external API why not using an extension of the VFIO_DEVICE_SET_IRQS and use directly the VFIO device to setup interrupts? see following ----v > >>>> >>>> @Alex, what do you think? >>>> >>>> Regards, >>>> Pierre >>>> >>> >>> As I understand it the question isn't if it is specific to KVM but >>> rather if it is specific to virtualization. As vfio-pci is also used >>> for non virtualization purposes such as with DPDK/SPDK or a fully >>> emulating QEMU, it should only be in VFIO if it is relevant for these >>> kinds of user-space PCI accesses too. I'm not an AEN expert but as I >>> understand it, this does forwarding interrupts into a SIE context which >>> only makes sense for virtualization not for general user-space PCI. > > Right, AEN forwarding is only relevant for virtual machines. > >>> >> >> Being in VFIO kernel part does not mean that this part should be >> called from any user of VFIO in userland. >> That is a reason why I did propose an extension and not using the >> current implementation of VFIO_DEVICE_SET_IRQS as is. >> >> The reason behind is that the AEN hardware handling is device >> specific: we need the Function Handle to program AEN. > > You also need the GISA designation which is provided by the kvm or you > also can't program AEN.  So you ultimately need both a function handle > that is 'owned' by the device (vfio device fd) and the GISA designation > that is 'owned' by kvm (kvm fd).  So there are 2 different "owning" fds > involved. Yes GISA is a host structure, not device specific but guest specific and exist very soon during the guest creation, there should be no problem to retrieve it from a VFIO device IOTCL. > >> >> If the API is through KVM which is device agnostic the implementation >> in KVM has to search through the system to find the device being >> handled to apply AEN on it. > > See comment above about instead passing the vfio device fd. > >> >> This not the logical way for me and it is a potential source of >> problems for future extensions. >> > > > ^------ There are three different things to modify for the Z-guest to use VFIO: - IOMMU - device IRQ - instruction interpretation, feature negociation For my opinion only the last one should go directly through the KVM fd. This should be possible for all architectures. If it is not possible for Z, the failing path must be adapted it should not go through another path. Giving the right IRQ information to the host can be done with a dedicated IOCTL through the VFIO device fd, just like we need an extension in the other direction to retrieve the Z specific capabilities. I am quite sure that other architectures will need some specificity too for the interrupt or IOMMU handling in the future with increasing implementation of virtualization in the firmware. Having a dedicated IOCTL command means it can be called from QEMU and for guest virtualizuation only then let unused for other userland access. Regards, Pierre -- Pierre Morel IBM Lab Boeblingen