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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable 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 AB9AAC3524F for ; Wed, 5 Feb 2020 06:19:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8AEB6217F4 for ; Wed, 5 Feb 2020 06:19:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726277AbgBEGTh convert rfc822-to-8bit (ORCPT ); Wed, 5 Feb 2020 01:19:37 -0500 Received: from mga07.intel.com ([134.134.136.100]:52004 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725385AbgBEGTh (ORCPT ); Wed, 5 Feb 2020 01:19:37 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Feb 2020 22:19:35 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,404,1574150400"; d="scan'208";a="343167986" Received: from fmsmsx103.amr.corp.intel.com ([10.18.124.201]) by fmsmga001.fm.intel.com with ESMTP; 04 Feb 2020 22:19:34 -0800 Received: from fmsmsx609.amr.corp.intel.com (10.18.126.89) by FMSMSX103.amr.corp.intel.com (10.18.124.201) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 4 Feb 2020 22:19:34 -0800 Received: from fmsmsx609.amr.corp.intel.com (10.18.126.89) by fmsmsx609.amr.corp.intel.com (10.18.126.89) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Tue, 4 Feb 2020 22:19:34 -0800 Received: from shsmsx102.ccr.corp.intel.com (10.239.4.154) by fmsmsx609.amr.corp.intel.com (10.18.126.89) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.1713.5 via Frontend Transport; Tue, 4 Feb 2020 22:19:33 -0800 Received: from shsmsx104.ccr.corp.intel.com ([169.254.5.5]) by shsmsx102.ccr.corp.intel.com ([169.254.2.126]) with mapi id 14.03.0439.000; Wed, 5 Feb 2020 14:19:32 +0800 From: "Liu, Yi L" To: Alex Williamson CC: "eric.auger@redhat.com" , "Tian, Kevin" , "jacob.jun.pan@linux.intel.com" , "joro@8bytes.org" , "Raj, Ashok" , "Tian, Jun J" , "Sun, Yi Y" , "jean-philippe.brucker@arm.com" , "peterx@redhat.com" , "iommu@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [RFC v3 4/8] vfio/type1: Add VFIO_NESTING_GET_IOMMU_UAPI_VERSION Thread-Topic: [RFC v3 4/8] vfio/type1: Add VFIO_NESTING_GET_IOMMU_UAPI_VERSION Thread-Index: AQHV1pyVzTVYYyC090Ow388f+bA35qgBzDSAgALuTFCABInhgIAC5JFQ Date: Wed, 5 Feb 2020 06:19:31 +0000 Message-ID: References: <1580299912-86084-1-git-send-email-yi.l.liu@intel.com> <1580299912-86084-5-git-send-email-yi.l.liu@intel.com> <20200129165649.43008300@w520.home> <20200203110045.1fb3ec8d@w520.home> In-Reply-To: <20200203110045.1fb3ec8d@w520.home> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-version: 11.2.0.6 dlp-reaction: no-action x-ctpclassification: CTP_NT x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiMDljNmJkZDgtYjc0Yi00MGNhLTkyZWUtOTIwMmI0ZjY2OWIyIiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX05UIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE3LjEwLjE4MDQuNDkiLCJUcnVzdGVkTGFiZWxIYXNoIjoiakkxU2NRcEg3R3NIdEM1d1JhblhWZTc5UVZqSTZaU0ZCUFFHbHlrSnhaMlc4SlBGQWFhWmZHOVFIaUliQUc5ZCJ9 x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org > From: Alex Williamson [mailto:alex.williamson@redhat.com] > Sent: Tuesday, February 4, 2020 2:01 AM > To: Liu, Yi L > Subject: Re: [RFC v3 4/8] vfio/type1: Add > VFIO_NESTING_GET_IOMMU_UAPI_VERSION > > On Fri, 31 Jan 2020 13:04:11 +0000 > "Liu, Yi L" wrote: > > > Hi Alex, > > > > > From: Alex Williamson [mailto:alex.williamson@redhat.com] > > > Sent: Thursday, January 30, 2020 7:57 AM > > > To: Liu, Yi L > > > Subject: Re: [RFC v3 4/8] vfio/type1: Add > > > VFIO_NESTING_GET_IOMMU_UAPI_VERSION > > > > > > On Wed, 29 Jan 2020 04:11:48 -0800 > > > "Liu, Yi L" wrote: > > > > > > > From: Liu Yi L > > > > > > > > In Linux Kernel, the IOMMU nesting translation (a.k.a. IOMMU dual stage > > > > translation capability) is abstracted in uapi/iommu.h, in which the uAPIs > > > > like bind_gpasid/iommu_cache_invalidate/fault_report/pgreq_resp are defined. > > > > > > > > VFIO_TYPE1_NESTING_IOMMU stands for the vfio iommu type which is backed > by > > > > IOMMU nesting translation capability. VFIO exposes the nesting capability > > > > to userspace and also exposes uAPIs (will be added in later patches) to user > > > > space for setting up nesting translation from userspace. Thus applications > > > > like QEMU could support vIOMMU for pass-through devices with IOMMU > nesting > > > > translation capability. > > > > > > > > As VFIO expose the nesting IOMMU programming to userspace, it also needs to > > > > provide an API for the uapi/iommu.h version check to ensure compatibility. > > > > This patch reports the iommu uapi version to userspace. Applications could > > > > use this API to do version check before further using the nesting uAPIs. > > > > > > > > Cc: Kevin Tian > > > > CC: Jacob Pan > > > > Cc: Alex Williamson > > > > Cc: Eric Auger > > > > Cc: Jean-Philippe Brucker > > > > Signed-off-by: Liu Yi L > > > > --- > > > > drivers/vfio/vfio.c | 3 +++ > > > > include/uapi/linux/vfio.h | 10 ++++++++++ > > > > 2 files changed, 13 insertions(+) > > > > > > > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c > > > > index 425d60a..9087ad4 100644 > > > > --- a/drivers/vfio/vfio.c > > > > +++ b/drivers/vfio/vfio.c > > > > @@ -1170,6 +1170,9 @@ static long vfio_fops_unl_ioctl(struct file *filep, > > > > case VFIO_GET_API_VERSION: > > > > ret = VFIO_API_VERSION; > > > > break; > > > > + case VFIO_NESTING_GET_IOMMU_UAPI_VERSION: > > > > + ret = iommu_get_uapi_version(); > > > > + break; > > > > > > Shouldn't the type1 backend report this? It doesn't make much sense > > > that the spapr backend reports a version for something it doesn't > > > support. Better yet, provide this info gratuitously in the > > > VFIO_IOMMU_GET_INFO ioctl return like you do with nesting in the next > > > patch, then it can help the user figure out if this support is present. > > > > yeah, it would be better to report it by type1 backed. However, > > it is kind of issue when QEMU using it. > > > > My series "hooks" vSVA supports on VFIO_TYPE1_NESTING_IOMMU type. > > [RFC v3 09/25] vfio: check VFIO_TYPE1_NESTING_IOMMU support > > https://www.spinics.net/lists/kvm/msg205197.html > > > > In QEMU, it will determine the iommu type firstly and then invoke > > VFIO_SET_IOMMU. I think before selecting VFIO_TYPE1_NESTING_IOMMU, > > QEMU needs to check the IOMMU uAPI version. If IOMMU uAPI is incompatible, > > QEMU should not use VFIO_TYPE1_NESTING_IOMMU type. If > > VFIO_NESTING_GET_IOMMU_UAPI_VERSION is available after set iommu, then it > > may be an issue. That's why this series reports the version in vfio layer > > instead of type1 backend. > > Why wouldn't you use CHECK_EXTENSION? You could probe specifically for > a VFIO_TYP1_NESTING_IOMMU_UAPI_VERSION extension that returns the > version number. Thanks, oh, yes. Thanks for this guiding. :-) Regards, Yi Liu