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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 27430CA9EBD for ; Fri, 25 Oct 2019 15:52:46 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 E811B21D82 for ; Fri, 25 Oct 2019 15:52:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E811B21D82 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 9E969CA8; Fri, 25 Oct 2019 15:52:45 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 1EBA0C6A for ; Fri, 25 Oct 2019 15:52:44 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id B32B987E for ; Fri, 25 Oct 2019 15:52:43 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Oct 2019 08:52:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,229,1569308400"; d="scan'208";a="282292991" Received: from fmsmsx105.amr.corp.intel.com ([10.18.124.203]) by orsmga001.jf.intel.com with ESMTP; 25 Oct 2019 08:52:41 -0700 Received: from fmsmsx156.amr.corp.intel.com (10.18.116.74) by FMSMSX105.amr.corp.intel.com (10.18.124.203) with Microsoft SMTP Server (TLS) id 14.3.439.0; Fri, 25 Oct 2019 08:52:41 -0700 Received: from shsmsx153.ccr.corp.intel.com (10.239.6.53) by fmsmsx156.amr.corp.intel.com (10.18.116.74) with Microsoft SMTP Server (TLS) id 14.3.439.0; Fri, 25 Oct 2019 08:52:41 -0700 Received: from shsmsx104.ccr.corp.intel.com ([169.254.5.166]) by SHSMSX153.ccr.corp.intel.com ([10.239.6.53]) with mapi id 14.03.0439.000; Fri, 25 Oct 2019 23:52:39 +0800 From: "Tian, Kevin" To: Lu Baolu , Jacob Pan Subject: RE: [PATCH v7 03/11] iommu/vt-d: Add custom allocator for IOASID Thread-Topic: [PATCH v7 03/11] iommu/vt-d: Add custom allocator for IOASID Thread-Index: AQHViqRVDFt/7gHf3E+EfuPtxXQ8nKdqHQYAgAAk/YCAAKNMUIAAA0iAgACaPUA= Date: Fri, 25 Oct 2019 15:52:39 +0000 Message-ID: References: <1571946904-86776-1-git-send-email-jacob.jun.pan@linux.intel.com> <1571946904-86776-4-git-send-email-jacob.jun.pan@linux.intel.com> <20191024214311.43d76a5c@jacob-builder> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ctpclassification: CTP_NT x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiMmFmZjZmYjctOTM0NC00NDg5LWIxMzMtMDRmYjJmZTY1OTA4IiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX05UIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE3LjEwLjE4MDQuNDkiLCJUcnVzdGVkTGFiZWxIYXNoIjoibTRTM1RTWTlRN20zYmtjSDI0OStFVnFUNnkzNW5ucU83YUxoUGlzM05CbWgwdEtsc0J1UkR1SnJlSkkreXNBRCJ9 dlp-product: dlpe-windows dlp-version: 11.0.400.15 dlp-reaction: no-action x-originating-ip: [10.239.127.40] MIME-Version: 1.0 Cc: "Raj, Ashok" , David Woodhouse , "iommu@lists.linux-foundation.org" , LKML , Alex Williamson , Jean-Philippe Brucker , Jonathan Cameron X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org > From: Lu Baolu [mailto:baolu.lu@linux.intel.com] > Sent: Friday, October 25, 2019 10:39 PM > > Hi, > > On 10/25/19 2:40 PM, Tian, Kevin wrote: > >>>> ioasid_register_allocator(&iommu->pasid_allocator); > >>>> + if (ret) { > >>>> + pr_warn("Custom PASID allocator > >>>> registeration failed\n"); > >>>> + /* > >>>> + * Disable scalable mode on this > >>>> IOMMU if there > >>>> + * is no custom allocator. Mixing > >>>> SM capable vIOMMU > >>>> + * and non-SM vIOMMU are not > >>>> supported. > >>>> + */ > >>>> + intel_iommu_sm = 0; > >>> It's insufficient to disable scalable mode by only clearing > >>> intel_iommu_sm. The DMA_RTADDR_SMT bit in root entry has already > >> been > >>> set. Probably, you need to > >>> > >>> for each iommu > >>> clear DMA_RTADDR_SMT in root entry > >>> > >>> Alternatively, since vSVA is the only customer of this custom PASID > >>> allocator, is it possible to only disable SVA here? > >>> > >> Yeah, I think disable SVA is better. We can still do gIOVA in SM. I > >> guess we need to introduce a flag for sva_enabled. > > I'm not sure whether tying above logic to SVA is the right approach. > > If vcmd interface doesn't work, the whole SM mode doesn't make > > sense which is based on PASID-granular protection (SVA is only one > > usage atop). If the only remaining usage of SM is to map gIOVA using > > reserved PASID#0, then why not disabling SM and just fallback to > > legacy mode? > > > > Based on that I prefer to disabling the SM mode completely (better > > through an interface), and move the logic out of CONFIG_INTEL_ > > IOMMU_SVM > > > > Unfortunately, it is dangerous to disable SM after boot. SM uses > different root/device contexts and pasid table formats. Disabling SM > after boot requires changing above from SM format into legacy format. You are correct. > > Since ioasid registration failure is a rare case. How about moving this > part of code up to the early stage of intel_iommu_init() and returning > error if hardware present vcmd capability but software fails to register > a custom ioasid allocator? > It makes sense to me. Thanks Kevin _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu