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 1055EC2BB85 for ; Thu, 16 Apr 2020 10:41:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E535421D92 for ; Thu, 16 Apr 2020 10:41:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2505611AbgDPKlZ convert rfc822-to-8bit (ORCPT ); Thu, 16 Apr 2020 06:41:25 -0400 Received: from mga03.intel.com ([134.134.136.65]:38453 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2505368AbgDPKkM (ORCPT ); Thu, 16 Apr 2020 06:40:12 -0400 IronPort-SDR: g2C2npSqDr9IzYjcOYzQDEV7QOdelRhOCPpKHYB/Xm4B8w2IG6yoiChLqnZ3GNjvMmrYPuMKXj 3vWbxg/myazw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Apr 2020 03:40:08 -0700 IronPort-SDR: xNHXCsemG8ocpE+IioNARwcyCC2nV/4MzsdvoKLGtCR7+CYIAKlmQEHwym/WVaKMczxdRNkkGx LTzmLvUYZQng== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,390,1580803200"; d="scan'208";a="332798286" Received: from fmsmsx105.amr.corp.intel.com ([10.18.124.203]) by orsmga001.jf.intel.com with ESMTP; 16 Apr 2020 03:40:08 -0700 Received: from fmsmsx154.amr.corp.intel.com (10.18.116.70) by FMSMSX105.amr.corp.intel.com (10.18.124.203) with Microsoft SMTP Server (TLS) id 14.3.439.0; Thu, 16 Apr 2020 03:40:07 -0700 Received: from shsmsx153.ccr.corp.intel.com (10.239.6.53) by FMSMSX154.amr.corp.intel.com (10.18.116.70) with Microsoft SMTP Server (TLS) id 14.3.439.0; Thu, 16 Apr 2020 03:40:06 -0700 Received: from shsmsx104.ccr.corp.intel.com ([169.254.5.225]) by SHSMSX153.ccr.corp.intel.com ([169.254.12.89]) with mapi id 14.03.0439.000; Thu, 16 Apr 2020 18:40:04 +0800 From: "Liu, Yi L" To: Alex Williamson , "Tian, Kevin" CC: "eric.auger@redhat.com" , "jacob.jun.pan@linux.intel.com" , "joro@8bytes.org" , "Raj, Ashok" , "Tian, Jun J" , "Sun, Yi Y" , "jean-philippe@linaro.org" , "peterx@redhat.com" , "iommu@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Wu, Hao" 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: AQHWAEUdcc1u01skwUmp6uBHREsZ66hl0sQAgACrzQCAAJWLAIAUkGLA Date: Thu, 16 Apr 2020 10:40:03 +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: <20200403093436.094b1928@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-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Thanks, Yi Liu