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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 6E9F5C433DB for ; Tue, 2 Mar 2021 09:47:20 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 C077B64E56 for ; Tue, 2 Mar 2021 09:47:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C077B64E56 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=virtualization-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 4EED643096; Tue, 2 Mar 2021 09:47:19 +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 MBfZ_ctD0oXu; Tue, 2 Mar 2021 09:47:18 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTP id 00B9843069; Tue, 2 Mar 2021 09:47:17 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id D7B24C000B; Tue, 2 Mar 2021 09:47:17 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 88186C0001 for ; Tue, 2 Mar 2021 09:47:16 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 6A7EE43083 for ; Tue, 2 Mar 2021 09:47:16 +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 3mEP63OuNg24 for ; Tue, 2 Mar 2021 09:47:15 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by smtp2.osuosl.org (Postfix) with ESMTPS id 36B2E43069 for ; Tue, 2 Mar 2021 09:47:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614678433; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lNvLI1zsChJgnJq9MCR6chFkbHYLQrCmCIxk0IHOWi0=; b=M+dAKLZjSqu6CP/RlZHBwlHFFF16JWR3ETMKb2ZsYxhieXBUWg8rIDCBEYSJCzUXdMM6hI o10FGW6VzC2Le7C8MwuLhHI5I97PuDxRZh51qFLXAEp4/zMlj/C/B7GS235ZbkhawiOx4C wcZSA+xLooZOhZuv+IFKZ6p4xoJLtYk= Received: from mail-ej1-f71.google.com (mail-ej1-f71.google.com [209.85.218.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-363-bBSyF4tfNfmA8IAbwfvekA-1; Tue, 02 Mar 2021 04:47:12 -0500 X-MC-Unique: bBSyF4tfNfmA8IAbwfvekA-1 Received: by mail-ej1-f71.google.com with SMTP id r26so2671488eja.22 for ; Tue, 02 Mar 2021 01:47:11 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=lNvLI1zsChJgnJq9MCR6chFkbHYLQrCmCIxk0IHOWi0=; b=TtxR5q2zSw41BWZ8dqDd05V7KpWjpGVo8g6N+fLZc2IHVu1b5vg/FGUlskt0IhzWBE 4NYSr2yGI2DXK5EM5mjBHVa4bbwq9KwDcSpbKmj2irlOJ5houHXLbfE9lsJAA9DAK93a DBcNlpcY2X/RUKpSp+Ux1B4ChGhYY7Xjdd8zZq03ABrxqpNBsDzijqBuu+JatdwjjUUm zPmC902ks6panon4PtRybWaFlfZ8WDKkdSDNfhvJ8A7juTpiJSd0ZNgb3EjTeKbxuNLL cWy0m03xqAgZzcyJZA6ll1PmhIScEzmLDQ6lsT4/XIi7592KwwXo5Mqz9z4Qjrb0tgs1 AepA== X-Gm-Message-State: AOAM530UjhNU5fJIYXc/VSdowDXaLQPSehGdQ1MOxKMkf1lZl3S9xHzd OzBUK30qlWy5jLFQ1a82dH7ap1/k56txwU+rNDBitUz2xa82jH4LR7FbyRep32BHmqedWT3bAmU sI7USV8lEi2A6B0RJAXa9IeOib/9xelhpdxYtSCuU/A== X-Received: by 2002:a17:906:fcb2:: with SMTP id qw18mr3047201ejb.434.1614678431039; Tue, 02 Mar 2021 01:47:11 -0800 (PST) X-Google-Smtp-Source: ABdhPJzjMhMEgexNSVGalvHgWj2+Bk230qklneo7u70O2OErqt4IfLk29fQciTb8d95u4L7fIeXDMQ== X-Received: by 2002:a17:906:fcb2:: with SMTP id qw18mr3047184ejb.434.1614678430896; Tue, 02 Mar 2021 01:47:10 -0800 (PST) Received: from redhat.com (bzq-79-180-2-31.red.bezeqint.net. [79.180.2.31]) by smtp.gmail.com with ESMTPSA id w8sm17455053edd.39.2021.03.02.01.47.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Mar 2021 01:47:10 -0800 (PST) Date: Tue, 2 Mar 2021 04:47:07 -0500 From: "Michael S. Tsirkin" To: Jason Wang Subject: Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero Message-ID: <20210302043419-mutt-send-email-mst@kernel.org> References: <605e7d2d-4f27-9688-17a8-d57191752ee7@redhat.com> <20210222023040-mutt-send-email-mst@kernel.org> <22fe5923-635b-59f0-7643-2fd5876937c2@oracle.com> <20210223082536-mutt-send-email-mst@kernel.org> <3ff5fd23-1db0-2f95-4cf9-711ef403fb62@oracle.com> <20210224000057-mutt-send-email-mst@kernel.org> <52836a63-4e00-ff58-50fb-9f450ce968d7@oracle.com> <20210228163031-mutt-send-email-mst@kernel.org> <2cb51a6d-afa0-7cd1-d6f2-6b153186eaca@redhat.com> MIME-Version: 1.0 In-Reply-To: <2cb51a6d-afa0-7cd1-d6f2-6b153186eaca@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: Si-Wei Liu , netdev@vger.kernel.org, elic@nvidia.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" T24gTW9uLCBNYXIgMDEsIDIwMjEgYXQgMTE6NTY6NTBBTSArMDgwMCwgSmFzb24gV2FuZyB3cm90 ZToKPiAKPiBPbiAyMDIxLzMvMSA1OjM0IOS4iuWNiCwgTWljaGFlbCBTLiBUc2lya2luIHdyb3Rl Ogo+ID4gT24gV2VkLCBGZWIgMjQsIDIwMjEgYXQgMTA6MjQ6NDFBTSAtMDgwMCwgU2ktV2VpIExp dSB3cm90ZToKPiA+ID4gPiBEZXRlY3RpbmcgaXQgaXNuJ3QgZW5vdWdoIHRob3VnaCwgd2Ugd2ls bCBuZWVkIGEgbmV3IGlvY3RsIHRvIG5vdGlmeQo+ID4gPiA+IHRoZSBrZXJuZWwgdGhhdCBpdCdz IGEgbGVnYWN5IGd1ZXN0LiBVZ2ggOigKPiA+ID4gV2VsbCwgYWx0aG91Z2ggSSB0aGluayBhZGRp bmcgYW4gaW9jdGwgaXMgZG9hYmxlLCBtYXkgSSBrbm93IHdoYXQgdGhlIHVzZQo+ID4gPiBjYXNl IHRoZXJlIHdpbGwgYmUgZm9yIGtlcm5lbCB0byBsZXZlcmFnZSBzdWNoIGluZm8gZGlyZWN0bHk/ IElzIHRoZXJlIGEKPiA+ID4gY2FzZSBRRU1VIGNhbid0IGRvIHdpdGggZGVkaWNhdGUgaW9jdGxz IGxhdGVyIGlmIHRoZXJlJ3MgaW5kZWVkCj4gPiA+IGRpZmZlcmVudGlhdGlvbiAobGVnYWN5IHYu cy4gbW9kZXJuKSBuZWVkZWQ/Cj4gPiBCVFcgYSBnb29kIEFQSSBjb3VsZCBiZQo+ID4gCj4gPiAj ZGVmaW5lIFZIT1NUX1NFVF9FTkRJQU4gX0lPVyhWSE9TVF9WSVJUSU8sID8sIGludCkKPiA+ICNk ZWZpbmUgVkhPU1RfR0VUX0VORElBTiBfSU9XKFZIT1NUX1ZJUlRJTywgPywgaW50KQo+ID4gCj4g PiB3ZSBkaWQgaXQgcGVyIHZyaW5nIGJ1dCBtYXliZSB0aGF0IHdhcyBhIG1pc3Rha2UgLi4uCj4g Cj4gCj4gQWN0dWFsbHksIEkgd29uZGVyIHdoZXRoZXIgaXQncyBnb29kIHRpbWUgdG8ganVzdCBu b3Qgc3VwcG9ydCBsZWdhY3kgZHJpdmVyCj4gZm9yIHZEUEEuIENvbnNpZGVyOgo+IAo+IDEpIEl0 J3MgZGVmaW5pdGlvbiBpcyBuby1ub3JtYXRpdmUKPiAyKSBBIGxvdCBvZiBidWRyZW4gb2YgY29k ZXMKPiAKPiBTbyBxZW11IGNhbiBzdGlsbCBwcmVzZW50IHRoZSBsZWdhY3kgZGV2aWNlIHNpbmNl IHRoZSBjb25maWcgc3BhY2Ugb3Igb3RoZXIKPiBzdHVmZnMgdGhhdCBpcyBwcmVzZW50ZWQgYnkg dmhvc3QtdkRQQSBpcyBub3QgZXhwZWN0ZWQgdG8gYmUgYWNjZXNzZWQgYnkKPiBndWVzdCBkaXJl Y3RseS4gUWVtdSBjYW4gZG8gdGhlIGVuZGlhbiBjb252ZXJzaW9uIHdoZW4gbmVjZXNzYXJ5IGlu IHRoaXMKPiBjYXNlPwo+IAo+IFRoYW5rcwo+IAoKT3ZlcmFsbCBJIHdvdWxkIGJlIGZpbmUgd2l0 aCB0aGlzIGFwcHJvYWNoIGJ1dCB3ZSBuZWVkIHRvIGF2b2lkIGJyZWFraW5nCndvcmtpbmcgdXNl cnNwYWNlLCBxZW11IHJlbGVhc2VzIHdpdGggdmRwYSBzdXBwb3J0IGFyZSBvdXQgdGhlcmUgYW5k CnNlZW0gdG8gd29yayBmb3IgcGVvcGxlLiBBbnkgY2hhbmdlcyBuZWVkIHRvIHRha2UgdGhhdCBp bnRvIGFjY291bnQKYW5kIGRvY3VtZW50IGNvbXBhdGliaWxpdHkgY29uY2VybnMuIEkgbm90ZSB0 aGF0IGFueSBoYXJkd2FyZQppbXBsZW1lbnRhdGlvbiBpcyBhbHJlYWR5IGJyb2tlbiBmb3IgbGVn YWN5IGV4Y2VwdCBvbiBwbGF0Zm9ybXMgd2l0aApzdHJvbmcgb3JkZXJpbmcgd2hpY2ggbWlnaHQg YmUgaGVscGZ1bCBpbiByZWR1Y2luZyB0aGUgc2NvcGUuCgoKLS0gCk1TVAoKX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KVmlydHVhbGl6YXRpb24gbWFpbGlu ZyBsaXN0ClZpcnR1YWxpemF0aW9uQGxpc3RzLmxpbnV4LWZvdW5kYXRpb24ub3JnCmh0dHBzOi8v bGlzdHMubGludXhmb3VuZGF0aW9uLm9yZy9tYWlsbWFuL2xpc3RpbmZvL3ZpcnR1YWxpemF0aW9u 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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 C23F6C43332 for ; Tue, 2 Mar 2021 10:11:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA20A60240 for ; Tue, 2 Mar 2021 10:11:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349526AbhCBKEf (ORCPT ); Tue, 2 Mar 2021 05:04:35 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:20840 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379111AbhCBJto (ORCPT ); Tue, 2 Mar 2021 04:49:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614678433; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lNvLI1zsChJgnJq9MCR6chFkbHYLQrCmCIxk0IHOWi0=; b=M+dAKLZjSqu6CP/RlZHBwlHFFF16JWR3ETMKb2ZsYxhieXBUWg8rIDCBEYSJCzUXdMM6hI o10FGW6VzC2Le7C8MwuLhHI5I97PuDxRZh51qFLXAEp4/zMlj/C/B7GS235ZbkhawiOx4C wcZSA+xLooZOhZuv+IFKZ6p4xoJLtYk= Received: from mail-ej1-f69.google.com (mail-ej1-f69.google.com [209.85.218.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-18-DUXavz2jPAG6EBxC7dYO8A-1; Tue, 02 Mar 2021 04:47:12 -0500 X-MC-Unique: DUXavz2jPAG6EBxC7dYO8A-1 Received: by mail-ej1-f69.google.com with SMTP id au15so2760583ejc.8 for ; Tue, 02 Mar 2021 01:47:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=lNvLI1zsChJgnJq9MCR6chFkbHYLQrCmCIxk0IHOWi0=; b=Lt4AhefzdyZGP/qOCkhZWKoJUS0ZsUrr/qudk1uL2XY6Sp5k46Dp9Dtc8bHRFT2UWg 6SNJ5xTT12gMtPXlojCBOdTPTgwZNbszsu+8t0e3V6aVVzuVuKO1V2qCpYLbhzpFGYsH 8U1+HZsEgAtAHiccyKMtxP29UO+q4OQ914OCGXfh+cOsB5WX9STt0f/oH2iZap2p+8vT zS2lwRwGP0vlRK8EAQQXQKr3wjQE6NZYNOOkFPwlY1JxxLPT+UOFjmGlcUdjp1DGJzM6 bEraRzQa2KRL1L/MqdCAWgLEn8SUPsJal7mNVeSyxPZtmSuC2byIx0L0tQBkSgk3nc6f QsOw== X-Gm-Message-State: AOAM533pj7sePNfShwFEeDv4Ew4yXdrdZyripdPv2gHKQjlcdOiiCgXe A8lI6zKBsFR/p2LM5ooMCjcvwSGaleoFJH3lAnML/IVRZ4bbbKvjernk55tsx5YzfoTfbFnUNoI dGC5vWxkAyw5n+lKBh1AOO87E X-Received: by 2002:a17:906:fcb2:: with SMTP id qw18mr3047200ejb.434.1614678431039; Tue, 02 Mar 2021 01:47:11 -0800 (PST) X-Google-Smtp-Source: ABdhPJzjMhMEgexNSVGalvHgWj2+Bk230qklneo7u70O2OErqt4IfLk29fQciTb8d95u4L7fIeXDMQ== X-Received: by 2002:a17:906:fcb2:: with SMTP id qw18mr3047184ejb.434.1614678430896; Tue, 02 Mar 2021 01:47:10 -0800 (PST) Received: from redhat.com (bzq-79-180-2-31.red.bezeqint.net. [79.180.2.31]) by smtp.gmail.com with ESMTPSA id w8sm17455053edd.39.2021.03.02.01.47.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Mar 2021 01:47:10 -0800 (PST) Date: Tue, 2 Mar 2021 04:47:07 -0500 From: "Michael S. Tsirkin" To: Jason Wang Cc: Si-Wei Liu , elic@nvidia.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero Message-ID: <20210302043419-mutt-send-email-mst@kernel.org> References: <605e7d2d-4f27-9688-17a8-d57191752ee7@redhat.com> <20210222023040-mutt-send-email-mst@kernel.org> <22fe5923-635b-59f0-7643-2fd5876937c2@oracle.com> <20210223082536-mutt-send-email-mst@kernel.org> <3ff5fd23-1db0-2f95-4cf9-711ef403fb62@oracle.com> <20210224000057-mutt-send-email-mst@kernel.org> <52836a63-4e00-ff58-50fb-9f450ce968d7@oracle.com> <20210228163031-mutt-send-email-mst@kernel.org> <2cb51a6d-afa0-7cd1-d6f2-6b153186eaca@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2cb51a6d-afa0-7cd1-d6f2-6b153186eaca@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 01, 2021 at 11:56:50AM +0800, Jason Wang wrote: > > On 2021/3/1 5:34 上午, Michael S. Tsirkin wrote: > > On Wed, Feb 24, 2021 at 10:24:41AM -0800, Si-Wei Liu wrote: > > > > Detecting it isn't enough though, we will need a new ioctl to notify > > > > the kernel that it's a legacy guest. Ugh :( > > > Well, although I think adding an ioctl is doable, may I know what the use > > > case there will be for kernel to leverage such info directly? Is there a > > > case QEMU can't do with dedicate ioctls later if there's indeed > > > differentiation (legacy v.s. modern) needed? > > BTW a good API could be > > > > #define VHOST_SET_ENDIAN _IOW(VHOST_VIRTIO, ?, int) > > #define VHOST_GET_ENDIAN _IOW(VHOST_VIRTIO, ?, int) > > > > we did it per vring but maybe that was a mistake ... > > > Actually, I wonder whether it's good time to just not support legacy driver > for vDPA. Consider: > > 1) It's definition is no-normative > 2) A lot of budren of codes > > So qemu can still present the legacy device since the config space or other > stuffs that is presented by vhost-vDPA is not expected to be accessed by > guest directly. Qemu can do the endian conversion when necessary in this > case? > > Thanks > Overall I would be fine with this approach but we need to avoid breaking working userspace, qemu releases with vdpa support are out there and seem to work for people. Any changes need to take that into account and document compatibility concerns. I note that any hardware implementation is already broken for legacy except on platforms with strong ordering which might be helpful in reducing the scope. -- MST