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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 0402BC47082 for ; Tue, 8 Jun 2021 08:55:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBEF96124B for ; Tue, 8 Jun 2021 08:55:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231256AbhFHI5S (ORCPT ); Tue, 8 Jun 2021 04:57:18 -0400 Received: from mout.kundenserver.de ([212.227.17.10]:39141 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230306AbhFHI5R (ORCPT ); Tue, 8 Jun 2021 04:57:17 -0400 Received: from [192.168.1.155] ([77.7.0.189]) by mrelayeu.kundenserver.de (mreue106 [212.227.15.183]) with ESMTPSA (Nemesis) id 1MqJZl-1l3PJU3uj5-00nR3j; Tue, 08 Jun 2021 10:55:04 +0200 Subject: Re: [RFC] /dev/ioasid uAPI proposal To: Jason Wang , Jason Gunthorpe Cc: Alex Williamson , "Tian, Kevin" , Jean-Philippe Brucker , "Jiang, Dave" , "Raj, Ashok" , "kvm@vger.kernel.org" , Jonathan Corbet , Robin Murphy , LKML , "iommu@lists.linux-foundation.org" , David Gibson , Kirti Wankhede , David Woodhouse , Gerd Hoffmann References: <20210602120111.5e5bcf93.alex.williamson@redhat.com> <20210602180925.GH1002214@nvidia.com> <20210602130053.615db578.alex.williamson@redhat.com> <20210602195404.GI1002214@nvidia.com> <20210602143734.72fb4fa4.alex.williamson@redhat.com> <6a9426d7-ed55-e006-9c4c-6b7c78142e39@redhat.com> <20210603130927.GZ1002214@nvidia.com> <65614634-1db4-7119-1a90-64ba5c6e9042@redhat.com> <20210604115805.GG1002214@nvidia.com> <895671cc-5ef8-bc1a-734c-e9e2fdf03652@redhat.com> <20210607141424.GF1002214@nvidia.com> <1cf9651a-b8ee-11f1-1f70-db3492a76400@redhat.com> From: "Enrico Weigelt, metux IT consult" Message-ID: <9a5b6675-e21a-cf62-6ea1-66c07e73e3ae@metux.net> Date: Tue, 8 Jun 2021 10:54:59 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <1cf9651a-b8ee-11f1-1f70-db3492a76400@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Language: tl Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:8kyLIALPf2tB8V1k8OkKPO+t0JzfF1nw6+qQyhnu0hXMra8y0xE 6jTMAZv9U2q49s04k9XDHsGY7Zz+zj1PbDtCUSaFUayZkcDZhg5noOdzNDTmj9H5JfgBRxU tVmITHaGAVxeS/NootJaf9Wo7ND6rbtDzVmKjhhZZB0rh/Od2LmuGKGmpZUJBOU76UkahDH qjbSLLC8JG6uwi9xeZH+A== X-UI-Out-Filterresults: notjunk:1;V03:K0:NKHch6yJ0Zc=:rOP7klmWM3f3oIrFW9VpKr BBvV9RaWe6aDGtA16XwYrQ1FvLMQJgy+7wg1T/6mpmISE3kI7YbMzFteDBiF6Bh+QSEWYoAg2 RhexYbCbDtd8B1PG7fUL8pxQhgWJUn3diCm5hVw1lAxrwI3UeyJPiFXCScCM70WacprM/ws+G UY35oxJu1qeyt7h5tbpNj6uHw2utJco6lAKKYKK4nMPQcedVrLp73PbZQEKhdQGsMHmWRhpAs ZFxgp3QPNWmGqa/0NazChPNcDsWJZ2tUuE4XMjSGHtDJfda8VdD6iQjPxZkZXA+3ouU7vRJhZ BM75tNyPemu2xLiD5SKq3Smg4DaLPhQZZgIhbXGld3sHVs5pGtZfXDHPjIyIBsYdK5Q1/4g/j szIm6tHXksp4KbolEcOf+SEjJ1dazkoNzXznRvFao7oxpSuwYV8bIJBsuTosFUdTpNck5omTL 9B1TmZUX8SAc/S3jB4aJSDDHL72Ob833jj/WG8RWmKr2lh8A7eCyv0vwsRnKHelgu92Hu+jzR upIGX+uczX+fYEzNP2pysc= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.06.21 03:00, Jason Wang wrote: Hi folks, > Just to make sure we are in the same page. What I meant is, if the DMA > behavior like (no-snoop) is device specific. There's no need to mandate > a virtio general attributes. We can describe it per device. The devices > implemented in the current spec does not use non-coherent DMA doesn't > mean any future devices won't do that. The driver could choose to use > transport (e.g PCI), platform (ACPI) or device specific (general virtio > command) way to detect and flush cache when necessary. Maybe I've totally misunderstood the whole issue, but what I've learned to far: * it's a performance improvement for certain scenarios * whether it can be used depends on the devices as well as the underlying transport (combination of both) * whether it should be used (when possible) can only be decided by the driver Correct ? I tend to believe that's something that virtio infrastructure should handle in a generic way. Maybe the device as well as the transport could announce their capability (which IMHO should go via the virtio protocol), and if both are capable, the (guest's) virtio subsys tells the driver whether it's usable for a specific device. Perhaps we should also have a mechanism to tell the device that it's actually used. Sorry, if i'm completely on the wrong page and just talking junk here :o --mtx -- --- Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert werden ! Für eine vertrauliche Kommunikation senden Sie bitte ihren GPG/PGP-Schlüssel zu. --- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287 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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 25222C47082 for ; Tue, 8 Jun 2021 08:55:32 +0000 (UTC) Received: from smtp4.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 C1F9961263 for ; Tue, 8 Jun 2021 08:55:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C1F9961263 Authentication-Results: mail.kernel.org; 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Tue, 8 Jun 2021 08:55:28 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 2D90A4018C for ; Tue, 8 Jun 2021 08:55:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Vy3LoGl3ZLKr for ; Tue, 8 Jun 2021 08:55:27 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from mout.kundenserver.de (mout.kundenserver.de [212.227.17.10]) by smtp2.osuosl.org (Postfix) with ESMTPS id 05FF340109 for ; Tue, 8 Jun 2021 08:55:26 +0000 (UTC) Received: from [192.168.1.155] ([77.7.0.189]) by mrelayeu.kundenserver.de (mreue106 [212.227.15.183]) with ESMTPSA (Nemesis) id 1MqJZl-1l3PJU3uj5-00nR3j; Tue, 08 Jun 2021 10:55:04 +0200 Subject: Re: [RFC] /dev/ioasid uAPI proposal To: Jason Wang , Jason Gunthorpe References: <20210602120111.5e5bcf93.alex.williamson@redhat.com> <20210602180925.GH1002214@nvidia.com> <20210602130053.615db578.alex.williamson@redhat.com> <20210602195404.GI1002214@nvidia.com> <20210602143734.72fb4fa4.alex.williamson@redhat.com> <6a9426d7-ed55-e006-9c4c-6b7c78142e39@redhat.com> <20210603130927.GZ1002214@nvidia.com> <65614634-1db4-7119-1a90-64ba5c6e9042@redhat.com> <20210604115805.GG1002214@nvidia.com> <895671cc-5ef8-bc1a-734c-e9e2fdf03652@redhat.com> <20210607141424.GF1002214@nvidia.com> <1cf9651a-b8ee-11f1-1f70-db3492a76400@redhat.com> From: "Enrico Weigelt, metux IT consult" Message-ID: <9a5b6675-e21a-cf62-6ea1-66c07e73e3ae@metux.net> Date: Tue, 8 Jun 2021 10:54:59 +0200 User-Agent: Mozilla/5.0 (X11; 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charset="utf-8"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" T24gMDguMDYuMjEgMDM6MDAsIEphc29uIFdhbmcgd3JvdGU6CgpIaSBmb2xrcywKCj4gSnVzdCB0 byBtYWtlIHN1cmUgd2UgYXJlIGluIHRoZSBzYW1lIHBhZ2UuIFdoYXQgSSBtZWFudCBpcywgaWYg dGhlIERNQSAKPiBiZWhhdmlvciBsaWtlIChuby1zbm9vcCkgaXMgZGV2aWNlIHNwZWNpZmljLiBU aGVyZSdzIG5vIG5lZWQgdG8gbWFuZGF0ZSAKPiBhIHZpcnRpbyBnZW5lcmFsIGF0dHJpYnV0ZXMu IFdlIGNhbiBkZXNjcmliZSBpdCBwZXIgZGV2aWNlLiBUaGUgZGV2aWNlcyAKPiBpbXBsZW1lbnRl ZCBpbiB0aGUgY3VycmVudCBzcGVjIGRvZXMgbm90IHVzZSBub24tY29oZXJlbnQgRE1BIGRvZXNu J3QgCj4gbWVhbiBhbnkgZnV0dXJlIGRldmljZXMgd29uJ3QgZG8gdGhhdC4gVGhlIGRyaXZlciBj b3VsZCBjaG9vc2UgdG8gdXNlIAo+IHRyYW5zcG9ydCAoZS5nIFBDSSksIHBsYXRmb3JtIChBQ1BJ KSBvciBkZXZpY2Ugc3BlY2lmaWMgKGdlbmVyYWwgdmlydGlvIAo+IGNvbW1hbmQpIHdheSB0byBk ZXRlY3QgYW5kIGZsdXNoIGNhY2hlIHdoZW4gbmVjZXNzYXJ5LgoKTWF5YmUgSSd2ZSB0b3RhbGx5 IG1pc3VuZGVyc3Rvb2QgdGhlIHdob2xlIGlzc3VlLCBidXQgd2hhdCBJJ3ZlIGxlYXJuZWQKdG8g ZmFyOgoKKiBpdCdzIGEgcGVyZm9ybWFuY2UgaW1wcm92ZW1lbnQgZm9yIGNlcnRhaW4gc2NlbmFy aW9zCiogd2hldGhlciBpdCBjYW4gYmUgdXNlZCBkZXBlbmRzIG9uIHRoZSBkZXZpY2VzIGFzIHdl bGwgYXMgdGhlCiAgIHVuZGVybHlpbmcgdHJhbnNwb3J0IChjb21iaW5hdGlvbiBvZiBib3RoKQoq IHdoZXRoZXIgaXQgc2hvdWxkIGJlIHVzZWQgKHdoZW4gcG9zc2libGUpIGNhbiBvbmx5IGJlIGRl Y2lkZWQgYnkgdGhlCiAgIGRyaXZlcgoKQ29ycmVjdCA/CgpJIHRlbmQgdG8gYmVsaWV2ZSB0aGF0 J3Mgc29tZXRoaW5nIHRoYXQgdmlydGlvIGluZnJhc3RydWN0dXJlIHNob3VsZApoYW5kbGUgaW4g YSBnZW5lcmljIHdheS4KCk1heWJlIHRoZSBkZXZpY2UgYXMgd2VsbCBhcyB0aGUgdHJhbnNwb3J0 IGNvdWxkIGFubm91bmNlIHRoZWlyCmNhcGFiaWxpdHkgKHdoaWNoIElNSE8gc2hvdWxkIGdvIHZp YSB0aGUgdmlydGlvIHByb3RvY29sKSwgYW5kIGlmIGJvdGgKYXJlIGNhcGFibGUsIHRoZSAoZ3Vl c3QncykgdmlydGlvIHN1YnN5cyB0ZWxscyB0aGUgZHJpdmVyIHdoZXRoZXIgaXQncwp1c2FibGUg Zm9yIGEgc3BlY2lmaWMgZGV2aWNlLiBQZXJoYXBzIHdlIHNob3VsZCBhbHNvIGhhdmUgYSBtZWNo YW5pc20KdG8gdGVsbCB0aGUgZGV2aWNlIHRoYXQgaXQncyBhY3R1YWxseSB1c2VkLgoKClNvcnJ5 LCBpZiBpJ20gY29tcGxldGVseSBvbiB0aGUgd3JvbmcgcGFnZSBhbmQganVzdCB0YWxraW5nIGp1 bmsgaGVyZSA6bwoKCi0tbXR4CgotLSAKLS0tCkhpbndlaXM6IHVudmVyc2NobMO8c3NlbHRlIEUt TWFpbHMga8O2bm5lbiBsZWljaHQgYWJnZWjDtnJ0IHVuZCBtYW5pcHVsaWVydAp3ZXJkZW4gISBG w7xyIGVpbmUgdmVydHJhdWxpY2hlIEtvbW11bmlrYXRpb24gc2VuZGVuIFNpZSBiaXR0ZSBpaHJl bgpHUEcvUEdQLVNjaGzDvHNzZWwgenUuCi0tLQpFbnJpY28gV2VpZ2VsdCwgbWV0dXggSVQgY29u c3VsdApGcmVlIHNvZnR3YXJlIGFuZCBMaW51eCBlbWJlZGRlZCBlbmdpbmVlcmluZwppbmZvQG1l dHV4Lm5ldCAtLSArNDktMTUxLTI3NTY1Mjg3Cl9fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fCmlvbW11IG1haWxpbmcgbGlzdAppb21tdUBsaXN0cy5saW51eC1m b3VuZGF0aW9uLm9yZwpodHRwczovL2xpc3RzLmxpbnV4Zm91bmRhdGlvbi5vcmcvbWFpbG1hbi9s aXN0aW5mby9pb21tdQ==