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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 6A669C43387 for ; Fri, 18 Jan 2019 13:51:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40F1B2087E for ; Fri, 18 Jan 2019 13:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727602AbfARNv3 (ORCPT ); Fri, 18 Jan 2019 08:51:29 -0500 Received: from foss.arm.com ([217.140.101.70]:57386 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727134AbfARNv3 (ORCPT ); Fri, 18 Jan 2019 08:51:29 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 866BBEBD; Fri, 18 Jan 2019 05:51:28 -0800 (PST) Received: from [10.1.196.128] (ostrya.cambridge.arm.com [10.1.196.128]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2C0623F5C1; Fri, 18 Jan 2019 05:51:27 -0800 (PST) Subject: Re: [PATCH v1] iommu/s390: Declare s390 iommu reserved regions To: pmorel@linux.ibm.com, Robin Murphy , gerald.schaefer@de.ibm.com Cc: linux-s390@vger.kernel.org, walling@linux.ibm.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, alex.williamson@redhat.com References: <1547573850-9459-1-git-send-email-pmorel@linux.ibm.com> <3cd790d6-aa6f-e817-27ce-56d7a9b6b6e5@linux.ibm.com> From: Jean-Philippe Brucker Message-ID: <668fe734-e4bf-0342-ab8c-df54d9022db4@arm.com> Date: Fri, 18 Jan 2019 13:51:11 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <3cd790d6-aa6f-e817-27ce-56d7a9b6b6e5@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pierre, On 18/01/2019 13:29, Pierre Morel wrote: > On 17/01/2019 14:02, Robin Murphy wrote: >> On 15/01/2019 17:37, Pierre Morel wrote: >>> The s390 iommu can only allow DMA transactions between the zPCI device >>> entries start_dma and end_dma. >>> >>> Let's declare the regions before start_dma and after end_dma as >>> reserved regions using the appropriate callback in iommu_ops. >>> >>> The reserved region may later be retrieved from sysfs or from >>> the vfio iommu internal interface. >> >> For this particular case, I think the best solution is to give VFIO >> the ability to directly interrogate the domain geometry (which s390 >> appears to set correctly already). The idea of reserved regions was >> really for 'unexpected' holes inside the usable address space - using >> them to also describe places that are entirely outside that address >> space rather confuses things IMO. >> >> Furthermore, even if we *did* end up going down the route of actively >> reserving addresses beyond the usable aperture, it doesn't seem >> sensible for individual drivers to do it themselves when the core API >> already describes the relevant information generically. >> >> Robin. > > Robin, > > I already posted a patch retrieving the geometry through > VFIO_IOMMU_GET_INFO using a specific capability for the geometry [1], > and AFAIU, Alex did not agree with this. On arm we also need to report the IOMMU geometry to userspace (max IOVA size in particular). Shameer has been working on a solution [2] that presents a unified view of both geometry and reserved regions into the VFIO_IOMMU_GET_INFO call, and I think we should go with that. If I understand correctly it's currently blocked on the RMRR problem and we're waiting for Jacob or Ashok to take a look at it, as Kevin pinged them on thread [1]? [2] https://lkml.org/lkml/2018/4/18/293 Thanks, Jean > > What is different in what you propose? > > @Alex: I was hoping that this patch goes in your direction. What do you > think? > > Thanks, > Pierre > > [1]: https://lore.kernel.org/patchwork/patch/1030369/ > >> >>> >>> This seems to me related with the work Shameer has started on >>> vfio_iommu_type1 so I add Alex and Shameer to the CC list. >>> >>> >>> Pierre Morel (1): >>>    iommu/s390: Declare s390 iommu reserved regions >>> >>>   drivers/iommu/s390-iommu.c | 29 +++++++++++++++++++++++++++++ >>>   1 file changed, 29 insertions(+) >>> >> > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Philippe Brucker Subject: Re: [PATCH v1] iommu/s390: Declare s390 iommu reserved regions Date: Fri, 18 Jan 2019 13:51:11 +0000 Message-ID: <668fe734-e4bf-0342-ab8c-df54d9022db4@arm.com> References: <1547573850-9459-1-git-send-email-pmorel@linux.ibm.com> <3cd790d6-aa6f-e817-27ce-56d7a9b6b6e5@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <3cd790d6-aa6f-e817-27ce-56d7a9b6b6e5-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: pmorel-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org, Robin Murphy , gerald.schaefer-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org Cc: linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, walling-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org, alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org SGkgUGllcnJlLAoKT24gMTgvMDEvMjAxOSAxMzoyOSwgUGllcnJlIE1vcmVsIHdyb3RlOgo+IE9u IDE3LzAxLzIwMTkgMTQ6MDIsIFJvYmluIE11cnBoeSB3cm90ZToKPj4gT24gMTUvMDEvMjAxOSAx NzozNywgUGllcnJlIE1vcmVsIHdyb3RlOgo+Pj4gVGhlIHMzOTAgaW9tbXUgY2FuIG9ubHkgYWxs 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