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 61CB2C2BB55 for ; Thu, 16 Apr 2020 12:10:13 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 309BD20774 for ; Thu, 16 Apr 2020 12:10:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 309BD20774 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 localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id D851585FC7; Thu, 16 Apr 2020 12:10:12 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id eDgb_7a25N4M; Thu, 16 Apr 2020 12:10:08 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 042C586199; Thu, 16 Apr 2020 12:09:34 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id BDA4EC089E; Thu, 16 Apr 2020 12:09:33 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 1F74FC0172 for ; Thu, 16 Apr 2020 12:09:32 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 06117221C6 for ; Thu, 16 Apr 2020 12:09:32 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id yP8t4qjY55bc for ; Thu, 16 Apr 2020 12:09:30 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by silver.osuosl.org (Postfix) with ESMTPS id B43E8203F2 for ; Thu, 16 Apr 2020 12:09:30 +0000 (UTC) IronPort-SDR: zTR23lHozfxEjzzqXju/6rORpbY/a1U3BhizAwbXit3UcO4fMmtnyUI+yA0dxa7iUlYtiDc8HA wr5ufbDmTymA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Apr 2020 05:09:30 -0700 IronPort-SDR: 7/ajiPgfD/BuSBclgpGNfPwHnIMKHqpR58/pw/L7zRnXqSjCRTatWo3VkclArs9/eogSwWzkF+ L4fqzsXpsUIQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,390,1580803200"; d="scan'208";a="272049486" Received: from fmsmsx103.amr.corp.intel.com ([10.18.124.201]) by orsmga002.jf.intel.com with ESMTP; 16 Apr 2020 05:09:29 -0700 Received: from shsmsx152.ccr.corp.intel.com (10.239.6.52) by FMSMSX103.amr.corp.intel.com (10.18.124.201) with Microsoft SMTP Server (TLS) id 14.3.439.0; Thu, 16 Apr 2020 05:09:29 -0700 Received: from shsmsx104.ccr.corp.intel.com ([169.254.5.225]) by SHSMSX152.ccr.corp.intel.com ([169.254.6.209]) with mapi id 14.03.0439.000; Thu, 16 Apr 2020 20:09:26 +0800 From: "Tian, Kevin" To: "Liu, Yi L" , Alex Williamson Subject: RE: [PATCH v1 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE Thread-Topic: [PATCH v1 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE Thread-Index: AQHWAEUdbUtKvEWiiEiZu1SnRvWegKhl0sQAgAEuFaCAABNDAIAUHAOAgACdTsA= Date: Thu, 16 Apr 2020 12:09:25 +0000 Message-ID: References: <1584880325-10561-1-git-send-email-yi.l.liu@intel.com> <1584880325-10561-8-git-send-email-yi.l.liu@intel.com> <20200402142428.2901432e@w520.home> <20200403093436.094b1928@w520.home> In-Reply-To: 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-originating-ip: [10.239.127.40] MIME-Version: 1.0 Cc: "jean-philippe@linaro.org" , "Raj, Ashok" , "kvm@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "Sun, Yi Y" , "Tian, Jun J" , "Wu, Hao" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 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 Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" > From: Liu, Yi L > Sent: Thursday, April 16, 2020 6:40 PM > > Hi Alex, > Still have a direction question with you. Better get agreement with you > before heading forward. > > > From: Alex Williamson > > Sent: Friday, April 3, 2020 11:35 PM > [...] > > > > > + * > > > > > + * returns: 0 on success, -errno on failure. > > > > > + */ > > > > > +struct vfio_iommu_type1_cache_invalidate { > > > > > + __u32 argsz; > > > > > + __u32 flags; > > > > > + struct iommu_cache_invalidate_info cache_info; > > > > > +}; > > > > > +#define VFIO_IOMMU_CACHE_INVALIDATE _IO(VFIO_TYPE, > > VFIO_BASE > > > > + 24) > > > > > > > > The future extension capabilities of this ioctl worry me, I wonder if > > > > we should do another data[] with flag defining that data as > CACHE_INFO. > > > > > > Can you elaborate? Does it mean with this way we don't rely on iommu > > > driver to provide version_to_size conversion and instead we just pass > > > data[] to iommu driver for further audit? > > > > No, my concern is that this ioctl has a single function, strictly tied > > to the iommu uapi. If we replace cache_info with data[] then we can > > define a flag to specify that data[] is struct > > iommu_cache_invalidate_info, and if we need to, a different flag to > > identify data[] as something else. For example if we get stuck > > expanding cache_info to meet new demands and develop a new uapi to > > solve that, how would we expand this ioctl to support it rather than > > also create a new ioctl? There's also a trade-off in making the ioctl > > usage more difficult for the user. I'd still expect the vfio layer to > > check the flag and interpret data[] as indicated by the flag rather > > than just passing a blob of opaque data to the iommu layer though. > > Thanks, > > Based on your comments about defining a single ioctl and a unified > vfio structure (with a @data[] field) for pasid_alloc/free, bind/ > unbind_gpasid, cache_inv. After some offline trying, I think it would > be good for bind/unbind_gpasid and cache_inv as both of them use the > iommu uapi definition. While the pasid alloc/free operation doesn't. > It would be weird to put all of them together. So pasid alloc/free > may have a separate ioctl. It would look as below. Does this direction > look good per your opinion? > > ioctl #22: VFIO_IOMMU_PASID_REQUEST > /** > * @pasid: used to return the pasid alloc result when flags == ALLOC_PASID > * specify a pasid to be freed when flags == FREE_PASID > * @range: specify the allocation range when flags == ALLOC_PASID > */ > struct vfio_iommu_pasid_request { > __u32 argsz; > #define VFIO_IOMMU_ALLOC_PASID (1 << 0) > #define VFIO_IOMMU_FREE_PASID (1 << 1) > __u32 flags; > __u32 pasid; > struct { > __u32 min; > __u32 max; > } range; > }; > > ioctl #23: VFIO_IOMMU_NESTING_OP > struct vfio_iommu_type1_nesting_op { > __u32 argsz; > __u32 flags; > __u32 op; > __u8 data[]; > }; > > /* Nesting Ops */ > #define VFIO_IOMMU_NESTING_OP_BIND_PGTBL 0 > #define VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL 1 > #define VFIO_IOMMU_NESTING_OP_CACHE_INVLD 2 > Then why cannot we just put PASID into the header since the majority of nested usage is associated with a pasid? ioctl #23: VFIO_IOMMU_NESTING_OP struct vfio_iommu_type1_nesting_op { __u32 argsz; __u32 flags; __u32 op; __u32 pasid; __u8 data[]; }; In case of SMMUv2 which supports nested w/o PASID, this field can be ignored for that specific case. Thanks Kevin _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu