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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 03248C433ED for ; Wed, 12 May 2021 07:54:02 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 74AD261370 for ; Wed, 12 May 2021 07:54:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74AD261370 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 smtp1.osuosl.org (Postfix) with ESMTP id 13DC583D17; Wed, 12 May 2021 07:54:01 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id yvKs-qb7IP2f; Wed, 12 May 2021 07:54:00 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp1.osuosl.org (Postfix) with ESMTP id 6E6D183D0E; Wed, 12 May 2021 07:53:59 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 47A77C000D; Wed, 12 May 2021 07:53:59 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id D0AF6C0001 for ; Wed, 12 May 2021 07:53:57 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id AA01E4019A for ; Wed, 12 May 2021 07:53:57 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp2.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=redhat.com 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 mhMguWROvpa4 for ; Wed, 12 May 2021 07:53:56 +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 5079340015 for ; Wed, 12 May 2021 07:53:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620806035; 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=oLqmlEuhp9K1sh6b2eNpoKDd7Zyatg2EsHuk0cVSHtk=; b=WfE4gz+wBlgT29vm0OEus9W1AYOZbdvOaW4Er6BXtkCR6kg9SSzeRSJE/piC5TkUSrXkqw cGpIqPfhtS06m2iDI1yRkz9ZNGvr8XZtaIuioQhnzf0sXkgJdCNqNDFlwwib92nBB9mkZY O/Bpe9VnPdjXdRHN3CpYWHRWbWavtMQ= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-407-fM3S8tl1MZSqwjvpwWCqQA-1; Wed, 12 May 2021 03:53:51 -0400 X-MC-Unique: fM3S8tl1MZSqwjvpwWCqQA-1 Received: by mail-wm1-f71.google.com with SMTP id o126-20020a1c28840000b0290149b8f27c99so2699239wmo.2 for ; Wed, 12 May 2021 00:53:51 -0700 (PDT) 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=oLqmlEuhp9K1sh6b2eNpoKDd7Zyatg2EsHuk0cVSHtk=; b=GEQ+BhEaguJwzTo5AbehujZYRM7V5WAM/84Cd2jHBPeEVv4fG7dfCxUiat0RE6vvRN Cbu+IxnANR1PSct2pC0Qg2BnkBJuh3G0Bn50b8Yig9+GT8GZigAmo8aULgLuxpo4H9Ca alZXggzzB0CQgO2OK67zxO4GF6XW8HJoQrJtm5cHAqNMyVNGIroiXo4Ov0V4YE1vU06A GYyOm9XeviR/rzMFyOyPAhsjWNJGxEwAjFT2EwGAPfk02Rdgo8mExXcCFErXpcaN909D ZfJMKjhqmqsT8u5HJEJ131C2ltn5lsMwniIVEtbVA79MUzq01fUtLKVH22rOIAFW1nQT R4Pw== X-Gm-Message-State: AOAM533z4FaBrXaSb79eAuIEHGkZvTE32qrWOKwGzH17tqJruVtEkeH9 jJbPGkt9hGBdLlWXEhReAzHPSLxPPbjgB/8X46B3iPpizoVwwMqLPcWdFVvtf+Rq1LTKwYykuK3 zk13epRiDUZyaWc2u8I9vccbDN6ONjDj/3DySRvD0pg== X-Received: by 2002:a5d:6687:: with SMTP id l7mr44251691wru.235.1620806030328; Wed, 12 May 2021 00:53:50 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzWcYC1ZJV5ndKMfy0hWhlyn1mCsM2dWyCgry1CQpLkZu4SNNu5gsMBIrowg+nFlYrSK1Mh7g== X-Received: by 2002:a5d:6687:: with SMTP id l7mr44251663wru.235.1620806030104; Wed, 12 May 2021 00:53:50 -0700 (PDT) Received: from redhat.com ([2a10:8004:640e:0:d1db:1802:5043:7b85]) by smtp.gmail.com with ESMTPSA id r2sm31252563wrv.39.2021.05.12.00.53.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 May 2021 00:53:49 -0700 (PDT) Date: Wed, 12 May 2021 03:53:46 -0400 From: "Michael S. Tsirkin" To: Jason Wang Subject: Re: [RFC PATCH] vdpa: mandate 1.0 device Message-ID: <20210511061740-mutt-send-email-mst@kernel.org> References: <20210408082648.20145-1-jasowang@redhat.com> <20210409115343-mutt-send-email-mst@kernel.org> <42891807-cb24-5352-f8cb-798e9d1a1854@redhat.com> <20210412050730-mutt-send-email-mst@kernel.org> <01918e14-7f7a-abf2-5864-292a32f0233c@redhat.com> <20210421035331-mutt-send-email-mst@kernel.org> <3d5754f3-c012-67ad-5f01-fc16ec53df4e@redhat.com> <529543956.24692551.1620722593826.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 In-Reply-To: <529543956.24692551.1620722593826.JavaMail.zimbra@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: mapfelba@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, elic@nvidia.com, Lingshan Zhu 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" T24gVHVlLCBNYXkgMTEsIDIwMjEgYXQgMDQ6NDM6MTNBTSAtMDQwMCwgSmFzb24gV2FuZyB3cm90 ZToKPiAKPiAKPiAtLS0tLSDljp/lp4vpgq7ku7YgLS0tLS0KPiA+IAo+ID4g5ZyoIDIwMjEvNC8y MSDkuIvljYg0OjAzLCBNaWNoYWVsIFMuIFRzaXJraW4g5YaZ6YGTOgo+ID4gPiBPbiBXZWQsIEFw ciAyMSwgMjAyMSBhdCAwMzo0MTozNlBNICswODAwLCBKYXNvbiBXYW5nIHdyb3RlOgo+ID4gPj4g 5ZyoIDIwMjEvNC8xMiDkuIvljYg1OjIzLCBKYXNvbiBXYW5nIOWGmemBkzoKPiA+ID4+PiDlnKgg MjAyMS80LzEyIOS4i+WNiDU6MDksIE1pY2hhZWwgUy4gVHNpcmtpbiDlhpnpgZM6Cj4gPiA+Pj4+ IE9uIE1vbiwgQXByIDEyLCAyMDIxIGF0IDAyOjM1OjA3UE0gKzA4MDAsIEphc29uIFdhbmcgd3Jv dGU6Cj4gPiA+Pj4+PiDlnKggMjAyMS80LzEwIOS4iuWNiDEyOjA0LCBNaWNoYWVsIFMuIFRzaXJr aW4g5YaZ6YGTOgo+ID4gPj4+Pj4+IE9uIEZyaSwgQXByIDA5LCAyMDIxIGF0IDEyOjQ3OjU1UE0g KzA4MDAsIEphc29uIFdhbmcgd3JvdGU6Cj4gPiA+Pj4+Pj4+IOWcqCAyMDIxLzQvOCDkuIvljYgx MTo1OSwgTWljaGFlbCBTLiBUc2lya2luIOWGmemBkzoKPiA+ID4+Pj4+Pj4+IE9uIFRodSwgQXBy IDA4LCAyMDIxIGF0IDA0OjI2OjQ4UE0gKzA4MDAsIEphc29uIFdhbmcgd3JvdGU6Cj4gPiA+Pj4+ Pj4+Pj4gVGhpcyBwYXRjaCBtYW5kYXRlcyAxLjAgZm9yIHZEUEEgZGV2aWNlcy4gVGhlIGdvYWwg aXMgdG8gaGF2ZSB0aGUKPiA+ID4+Pj4+Pj4+PiBzZW1hbnRpYyBvZiBub3JtYXRpdmUgc3RhdGVt ZW50IGluIHRoZSB2aXJ0aW8KPiA+ID4+Pj4+Pj4+PiBzcGVjIGFuZCBlbGltaW5hdGUgdGhlCj4g PiA+Pj4+Pj4+Pj4gYnVyZGVuIG9mIHRyYW5zaXRpb25hbCBkZXZpY2UgZm9yIGJvdGggdkRQQSBi dXMgYW5kIHZEUEEgcGFyZW50Lgo+ID4gPj4+Pj4+Pj4+Cj4gPiA+Pj4+Pj4+Pj4gdUFQSSBzZWVt cyBmaW5lIHNpbmNlIGFsbCB0aGUgdkRQQSBwYXJlbnQgbWFuZGF0ZXMKPiA+ID4+Pj4+Pj4+PiBW SVJUSU9fRl9BQ0NFU1NfUExBVEZPUk0gd2hpY2ggaW1wbGllcyAxLjAgZGV2aWNlcy4KPiA+ID4+ Pj4+Pj4+Pgo+ID4gPj4+Pj4+Pj4+IEZvciBsZWdhY3kgZ3Vlc3RzLCBpdCBjYW4gc3RpbGwgd29y ayBzaW5jZSBRZW11IHdpbGwgbWVkaWF0ZSB3aGVuCj4gPiA+Pj4+Pj4+Pj4gbmVjZXNzYXJ5IChl LmcgZG9pbmcgdGhlIGVuZGlhbiBjb252ZXJzaW9uKS4KPiA+ID4+Pj4+Pj4+Pgo+ID4gPj4+Pj4+ Pj4+IFNpZ25lZC1vZmYtYnk6IEphc29uIFdhbmcgPGphc293YW5nQHJlZGhhdC5jb20+Cj4gPiA+ Pj4+Pj4+PiBIbW0uIElmIHdlIGRvIHRoaXMsIGRvbid0IHdlIHN0aWxsIGhhdmUgYSBwcm9ibGVt IHdpdGgKPiA+ID4+Pj4+Pj4+IGxlZ2FjeSBkcml2ZXJzIHdoaWNoIGRvbid0IGFjayAxLjA/Cj4g PiA+Pj4+Pj4+IFllcywgYnV0IGl0J3Mgbm90IHNvbWV0aGluZyB0aGF0IGlzIGludHJvZHVjZWQg aW4gdGhpcwo+ID4gPj4+Pj4+PiBjb21taXQuIFRoZSBsZWdhY3kKPiA+ID4+Pj4+Pj4gZHJpdmVy IG5ldmVyIHdvcmsgLi4uCj4gPiA+Pj4+Pj4gTXkgcG9pbnQgaXMgdGhpcyBuZWl0aGVyIGZpeGVz IG9yIHByZXZlbnRzIHRoaXMuCj4gPiA+Pj4+Pj4KPiA+ID4+Pj4+PiBTbyBteSBzdWdnZXN0aW9u IGlzIHRvIGZpbmFsbHkgYWRkIGlvY3RscyBhbG9uZyB0aGUgbGluZXMKPiA+ID4+Pj4+PiBvZiBQ Uk9UT0NPTF9GRUFUVVJFUyBvZiB2aG9zdC11c2VyLgo+ID4gPj4+Pj4+Cj4gPiA+Pj4+Pj4gVGhl biB0aGF0IG9uZSBjYW4gaGF2ZSBiaXRzIGZvciBsZWdhY3kgbGUsIGxlZ2FjeSBiZSBhbmQgbW9k ZXJuLgo+ID4gPj4+Pj4+Cj4gPiA+Pj4+Pj4gQlRXIEkgbG9va2VkIGF0IHZob3N0LXVzZXIgYW5k IGl0IGRvZXMgbm90IGxvb2sgbGlrZSB0aGF0Cj4gPiA+Pj4+Pj4gaGFzIGEgc29sdXRpb24gZm9y IHRoaXMgcHJvYmxlbSBlaXRoZXIsIHJpZ2h0Pwo+ID4gPj4+Pj4gUmlnaHQuCj4gPiA+Pj4+Pgo+ ID4gPj4+Pj4KPiA+ID4+Pj4+Pj4+IE5vdGUgMS4wIGFmZmVjdHMgcmluZyBlbmRpYW5uZXNzIHdo aWNoIGlzIG5vdCBtZWRpYXRlZCBpbiBRRU1VCj4gPiA+Pj4+Pj4+PiBzbyBRRU1VIGNhbid0IHBy ZXRlbmQgdG8gZGV2aWNlIGd1ZXN0IGlzIDEuMC4KPiA+ID4+Pj4+Pj4gUmlnaHQsIEkgcGxhbiB0 byBzZW5kIHBhdGNoZXMgdG8gZG8gbWVkaWF0aW9uIGluIHRoZQo+ID4gPj4+Pj4+PiBRZW11IHRv IHVuYnJlYWsgbGVnYWN5Cj4gPiA+Pj4+Pj4+IGRyaXZlcnMuCj4gPiA+Pj4+Pj4+Cj4gPiA+Pj4+ Pj4+IFRoYW5rcwo+ID4gPj4+Pj4+IEkgZnJhbmtseSB0aGluayB3ZSdsbCBuZWVkIFBST1RPQ09M X0ZFQVRVUkVTIGFueXdheSwgaXQncwo+ID4gPj4+Pj4+IHRvbyB1c2VmdWwgLi4uCj4gPiA+Pj4+ Pj4gc28gd2h5IG5vdCB0ZWFjaCBkcml2ZXJzIGFib3V0IGl0IGFuZCBiZSBkb25lIHdpdGggaXQ/ IFlvdQo+ID4gPj4+Pj4+IGNhbid0IGVtdWxhdGUKPiA+ID4+Pj4+PiBsZWdhY3kgb24gbW9kZXJu IGluIGEgY3Jvc3MgZW5kaWFuIHNpdHVhdGlvbiBiZWNhdXNlIG9mIHZyaW5nCj4gPiA+Pj4+Pj4g ZW5kaWFuLW5lc3MgLi4uCj4gPiA+Pj4+PiBTbyB0aGUgcHJvYmxlbSBzdGlsbC4gVGhpcyBjYW4g b25seSB3b3JrIHdoZW4gdGhlIGhhcmR3YXJlIGNhbiBzdXBwb3J0Cj4gPiA+Pj4+PiBsZWdhY3kg dnJpbmcgZW5kaWFuLW5lc3MuCj4gPiA+Pj4+Pgo+ID4gPj4+Pj4gQ29uc2lkZXI6Cj4gPiA+Pj4+ Pgo+ID4gPj4+Pj4gMSkgdGhlIGxlYWdjeSBkcml2ZXIgc3VwcG9ydCBpcyBub24tbm9ybWF0aXZl IGluIHRoZSBzcGVjCj4gPiA+Pj4+PiAyKSBzdXBwb3J0IGEgdHJhbnNpdGlvbmFsIGRldmljZSBp biB0aGUga2VucmVsIG1heSByZXF1aXJlcyB0aGUKPiA+ID4+Pj4+IGhhcmR3YXJlCj4gPiA+Pj4+ PiBzdXBwb3J0IGFuZCBhIGJ1cmRlbiBvZiBrZXJuZWwgY29kZXMKPiA+ID4+Pj4+Cj4gPiA+Pj4+ PiBJJ2QgcmF0aGVyIHNpbXBseSBkcm9wIHRoZSBsZWdhY3kgZHJpdmVyIHN1cHBvcnQKPiA+ID4+ Pj4gTXkgcG9pbnQgaXMgdGhpcyBwYXRjaCBkb2VzIG5vdCBkcm9wIGxlZ2FjeSBzdXBwb3J0LiBJ dCBtZXJlbHkgbWFuZGF0ZXMKPiA+ID4+Pj4gbW9kZXJuIHN1cHBvcnQuCj4gPiA+Pj4KPiA+ID4+ PiBJIGFtIG5vdCBzdXJlIEkgZ2V0IGhlcmUuIFRoaXMgcGF0Y2ggZmFpbHMgdGhlIHNldF9mZWF0 dXJlIGlmIFZFUlNJT05fMQo+ID4gPj4+IGlzIG5vdCBuZWdvdGlhdGVkLiBUaGlzIG1lYW5zOgo+ ID4gPj4+Cj4gPiA+Pj4gMSkgdkRQQSBwcmVzZW50cyBhIG1vZGVybiBkZXZpY2UgaW5zdGVhZCBv ZiB0cmFuc2l0b25hbCBkZXZpY2UKPiA+ID4+PiAyKSBsZWdhY3kgZHJpdmVyIGNhbid0IGJlIHBy b2JlZAo+ID4gPj4+Cj4gPiA+Pj4gV2hhdCBJJ20gbWlzc2luZz8KPiA+ID4+Cj4gPiA+PiBIaSBN aWNoYWVsOgo+ID4gPj4KPiA+ID4+IERvIHlvdSBhZ3JlZSB0byBmaW5kIHRoZSB3YXkgdG8gcHJl c2VudCBtb2Rlcm4gZGV2aWNlPyBXZSBuZWVkIGEKPiA+ID4+IGNvbmNsdXNpb24KPiA+ID4+IHRv IG1ha2UgdGhlIG5ldGxpbmsgQVBJIHdvcmsgdG8gbW92ZSBmb3J3YXJkLgo+ID4gPj4KPiA+ID4+ IFRoYW5rcwo+ID4gPiBJIHRoaW5rIHdlIG5lZWQgYSB3YXkgdG8gc3VwcG9ydCBsZWdhY3kgd2l0 aCBubyBkYXRhIHBhdGggb3ZlcmhlYWQuIHFlbXUKPiA+ID4gc2V0dGluZyBWRVJTSU9OXzEgZm9y IGEgbGVnYWN5IGd1ZXN0IGFmZmVjdHMgdGhlIHJpbmcgZm9ybWF0IHNvIGl0IGRvZXMKPiA+ID4g bm90IHJlYWxseSB3b3JrLiBUaGlzIHNlZW1zIHRvIHJ1bGUgb3V0IGVtdWxhdGluZyBjb25maWcg c3BhY2UgZW50aXJlbHkKPiA+ID4gaW4gdXNlcnNwYWNlLgo+ID4gCj4gPiAKPiA+IFNvIEknZCBy YXRoZXIgZHJvcCB0aGUgbGVnYWN5IHN1cHBvcnQgaW4gdGhpcyBjYXNlLiBJdCBuZXZlciB3b3Jr IGZvcgo+ID4gdkRQQSBpbiB0aGUgcGFzdCBhbmQgdmlydGlvLXZEUEEgZG9lc24ndCBldmVuIG5l ZWQgdGhhdC4gTm90ZSB0aGF0Cj4gPiBBQ0NFU1NfUExBVEZPUk0gaXMgbWFuZGF0ZWQgZm9yIGFs bCB0aGUgdkRQQSBwYXJlbnRzIHJpZ2h0IG5vdyB3aGljaAo+ID4gaW1wbGllcyBtb2Rlcm4gZGV2 aWNlIGFuZCBMRS4gSSB3b25kZXIgd2hhdCdzIHRoZSB2YWx1ZSBmb3Igc3VwcG9ydGluZwo+ID4g bGVnYWN5IGluIHRoaXMgY2FzZSBvciBkbyB3ZSByZWFsbHkgZW5jb3VyYWdlIHZlbmRvcnMgdG8g c2hpcCBjYXJkIHdpdGgKPiA+IGxlZ2FjeSBzdXBwb3J0IChlLmcgZW5kaWFuIHN1cHBvcnQgaW4g dGhlIGhhcmR3YXJlKT8KPiAKPiBIaSBNaWNoYWVsOgo+IAo+IEFueSB0aG91Z2h0cyBvbiB0aGlz IGFwcHJvYWNoPwo+IAo+IE15IHVuZGVyc3RhbmRpbmcgaXMgdGhhdCBkcm9wcGluZyBsZWdhY3kg c3VwcG9ydCB3aWxsIHNpbXBsaWZ5IGEgbG90IG9mIHN0dWZmcy4KPiAKPiBUaGFua3MKClNvIGJh c2ljYWxseSB0aGUgbWFpbiBjb25kaXRpb24gaXMgdGhhdCBzdHJvbmcgbWVtb3J5IGJhcnJpZXJz IGFyZW4ndApuZWVkZWQgZm9yIHZpcnRpbywgc21wIGJhcnJpZXJzIGFyZSBlbm91Z2guCkFyZSB0 aGVyZSBhcmNoaXRlY3R1cmVzIGJlc2lkZXMgeDg2ICh3aGVyZSBpdCdzIGtpbmQgb2YgdHJ1ZSAt IGFzIGxvbmcgYXMKb25lIGRvZXMgbm90IHVzZSBub24tdGVtcG9yYWxzKSB3aGVyZSB0aGF0IGlz IHRydWU/CklmIGFsbCB0aGVzZSBhcmNoaXRlY3R1cmVzIGFyZSBMRSB0aGVuIHdlIGRvbid0IG5l ZWQgdG8gd29ycnkKYWJvdXQgZW5kaWFuIHN1cHBvcnQgaW4gdGhlIGhhcmR3YXJlLgoKSW4gb3Ro ZXIgd29yZHMgSSBndWVzcyB5ZXMgd2UgY291bGQgaGF2ZSBxZW11IGxpbWl0IHRoaW5ncyB0byB4 ODYgYW5kCnRoZW4ganVzdCBwcmV0ZW5kIHRvIHRoZSBjYXJkIHRoYXQgaXQncyB2aXJ0aW8gMS4K U28gZW5kaWFuLW5lc3Mgd2UgY2FuIGFkZHJlc3MuCgpQcm9ibGVtIGlzIHZpcnRpbyAxIGhhcyBl ZmZlY3RzIGJleW9uZCB0aGlzLiB0aGluZ3MgbGlrZSBoZWFkZXIgc2l6ZQp3aXRoIG1lcmdlYWJs ZSBidWZmZXJzIG9mZiBmb3IgdmlydGlvIG5ldC4KClNvIEkgYW0gaW5jbGluZWQgdG8gc2F5IGxl dCB1cyBub3QgZG8gdGhlICJwcmV0ZW5kIGl0J3MgdmlydGlvIDEiIGdhbWUKaW4gcWVtdS4gIExl dCB1cyBiZSBob25lc3QgdG8gdGhlIGNhcmQgYWJvdXQgd2hhdCBoYXBwZW5zLgpCdXQgaWYgeW91 IHdhbnQgdG8gbGltaXQgdGhpbmdzIHRvIHg4NiBlaXRoZXIgaW4ga2VybmVsIG9yIGluIHFlbXUs CnRoYXQncyBvayBieSBtZS4KCj4gCj4gPiAKPiA+IAo+ID4gPgo+ID4gPiBTbyBJIHRoaW5rIHdl IHNob3VsZCBhZGQgYW4gaW9jdGwgYWxvbmcgdGhlIGxpbmVzIG9mCj4gPiA+IHByb3RvY29sIGZl YXR1cmVzLiBUaGVuIEkgdGhpbmsgd2UgY2FuIHJlc2VydmUgZmVhdHVyZSBiaXRzCj4gPiA+IGZv ciBjb25maWcgc3BhY2UgZm9ybWF0OiBsZWdhY3kgTEUsIGxlZ2FjeSBCRSwgbW9kZXJuLgo+ID4g Cj4gPiAKPiA+IFdlIGhhZCBWSE9TVF9TRVRfVlJJTkdfRU5ESUFOIGJ1dCB0aGlzIHdpbGwgY29t cGxpY2F0ZXMgYm90aCB0aGUgdkRQQQo+ID4gcGFyZW50IGFuZCBtYW5hZ2VtZW50LiBXaGF0J3Mg bW9yZSBpbXBvcnRhbnQsIGxlZ2FjeSBiZWhhdmlvdXIgaXMgbm90Cj4gPiByZXN0cmljdGllZCBi eSB0aGUgc3BlYy4KPiA+IAo+ID4gCj4gPiA+Cj4gPiA+IFF1ZXJ5aW5nIHRoZSBmZWF0dXJlIGJp dHMgd2lsbCBwcm92aWRlIHVzIHdpdGggaW5mbyBhYm91dAo+ID4gPiB3aGF0IGRvZXMgdGhlIGRl dmljZSBzdXBwb3J0LiBBY2tpbmcgdGhlbSB3aWxsIHRlbGwgZGV2aWNlCj4gPiA+IHdoYXQgZG9l cyBndWVzdCBuZWVkLgo+ID4gCj4gPiAKPiA+IEkgdGhpbmsgdGhpcyBjYW4gd29yaywgYnV0IEkg d29uZGVyIGhvdyBtdWNoIHdlIGNhbiBnYWluIGZyb20gc3VjaAo+ID4gY29tcGxleGl0aXkuCj4g PiAKPiA+IFRoYW5rcwo+ID4gCj4gPiAKPiA+ID4KPiA+ID4KPiA+ID4KPiA+ID4KPiA+ID4KPiA+ ID4+Pgo+ID4gPj4+Pj4gdG8gaGF2ZSBhIHNpbXBsZSBhbmQgZWFzeQo+ID4gPj4+Pj4gYWJzdGFy Y3Rpb24gaW4gdGhlIGtlbnJlbC4gRm9yIGxlZ2FjeSBkcml2ZXIgaW4gdGhlIGd1ZXN0LAo+ID4g Pj4+Pj4gaHlwZXJ2aXNvciBpcyBpbgo+ID4gPj4+Pj4gY2hhcmdlIG9mIHRoZSBtZWRpYXRpb246 Cj4gPiA+Pj4+Pgo+ID4gPj4+Pj4gMSkgY29uZmlnIHNwYWNlIGFjY2VzcyBlbmRpYW4gY29udmVy c2lvbgo+ID4gPj4+Pj4gMikgdXNpbmcgc2hhZG93IHZpcnRxdWV1ZSB0byBjaGFuZ2UgdGhlIGVu ZGlhbiBpbiB0aGUgdnJpbmcKPiA+ID4+Pj4+Cj4gPiA+Pj4+PiBUaGFua3MKPiA+ID4+Pj4gSSdk IGxpa2UgdG8gYXZvaWQgc2hhZG93IHZpcnRxdWV1ZSBoYWNrcyBpZiBhdCBhbGwgcG9zc2libGUu Cj4gPiA+Pj4+IExhc3QgSSBjaGVja2VkIHBlcmZvcm1hbmNlIHdhc24ndCBtdWNoIGJldHRlciB0 aGFuIGp1c3QgZW11bGF0aW5nCj4gPiA+Pj4+IHZpcnRpbyBpbiBzb2Z0d2FyZS4KPiA+ID4+Pgo+ ID4gPj4+IEkgdGhpbmsgdGhlIGxlZ2FjeSBkcml2ZXIgc3VwcG9ydCBpcyBqdXN0IGEgbmljZSB0 byBoYXZlLiBPciBkbyB5b3Ugc2VlCj4gPiA+Pj4gYW55IHZhbHVlIHRvIHRoYXQ/IEkgZ3Vlc3Mg Zm9yIG1lbGxhbm94IGFuZCBpbnRlbCwgb25seSBtb2Rlcm4gZGV2aWNlIGlzCj4gPiA+Pj4gc3Vw cG9ydGVkIGluIHRoZSBoYXJkd2FyZS4KPiA+ID4+Pgo+ID4gPj4+IFRoYW5rcwo+ID4gPj4+Cj4g PiA+Pj4KPiA+ID4+Pj4+Pj4+Cj4gPiA+Pj4+Pj4+Pgo+ID4gPj4+Pj4+Pj4+IC0tLQo+ID4gPj4+ Pj4+Pj4+ICDCoMKgwqAgaW5jbHVkZS9saW51eC92ZHBhLmggfCA2ICsrKysrKwo+ID4gPj4+Pj4+ Pj4+ICDCoMKgwqAgMSBmaWxlIGNoYW5nZWQsIDYgaW5zZXJ0aW9ucygrKQo+ID4gPj4+Pj4+Pj4+ Cj4gPiA+Pj4+Pj4+Pj4gZGlmZiAtLWdpdCBhL2luY2x1ZGUvbGludXgvdmRwYS5oIGIvaW5jbHVk ZS9saW51eC92ZHBhLmgKPiA+ID4+Pj4+Pj4+PiBpbmRleCAwZmVmZWI5NzY4NzcuLmNmZGU0ZWM5 OTliNCAxMDA2NDQKPiA+ID4+Pj4+Pj4+PiAtLS0gYS9pbmNsdWRlL2xpbnV4L3ZkcGEuaAo+ID4g Pj4+Pj4+Pj4+ICsrKyBiL2luY2x1ZGUvbGludXgvdmRwYS5oCj4gPiA+Pj4+Pj4+Pj4gQEAgLTYs NiArNiw3IEBACj4gPiA+Pj4+Pj4+Pj4gIMKgwqDCoCAjaW5jbHVkZSA8bGludXgvZGV2aWNlLmg+ Cj4gPiA+Pj4+Pj4+Pj4gIMKgwqDCoCAjaW5jbHVkZSA8bGludXgvaW50ZXJydXB0Lmg+Cj4gPiA+ Pj4+Pj4+Pj4gIMKgwqDCoCAjaW5jbHVkZSA8bGludXgvdmhvc3RfaW90bGIuaD4KPiA+ID4+Pj4+ Pj4+PiArI2luY2x1ZGUgPHVhcGkvbGludXgvdmlydGlvX2NvbmZpZy5oPgo+ID4gPj4+Pj4+Pj4+ ICDCoMKgwqAgLyoqCj4gPiA+Pj4+Pj4+Pj4gIMKgwqDCoMKgICogdkRQQSBjYWxsYmFjayBkZWZp bml0aW9uLgo+ID4gPj4+Pj4+Pj4+IEBAIC0zMTcsNiArMzE4LDExIEBAIHN0YXRpYyBpbmxpbmUg aW50Cj4gPiA+Pj4+Pj4+Pj4gdmRwYV9zZXRfZmVhdHVyZXMoc3RydWN0IHZkcGFfZGV2aWNlICp2 ZGV2LCB1NjQKPiA+ID4+Pj4+Pj4+PiBmZWF0dXJlcykKPiA+ID4+Pj4+Pj4+PiAgwqDCoMKgIHsK PiA+ID4+Pj4+Pj4+PiAgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoCBjb25zdCBzdHJ1Y3QgdmRwYV9j b25maWdfb3BzICpvcHMgPSB2ZGV2LT5jb25maWc7Cj4gPiA+Pj4+Pj4+Pj4gK8KgwqDCoMKgwqDC oMKgIC8qIE1hbmRhdGluZyAxLjAgdG8gaGF2ZSBzZW1hbnRpY3Mgb2YKPiA+ID4+Pj4+Pj4+PiBu b3JtYXRpdmUgc3RhdGVtZW50cyBpbgo+ID4gPj4+Pj4+Pj4+ICvCoMKgwqDCoMKgwqDCoMKgICog dGhlIHNwZWMuICovCj4gPiA+Pj4+Pj4+Pj4gK8KgwqDCoMKgwqDCoMKgIGlmICghKGZlYXR1cmVz ICYgQklUX1VMTChWSVJUSU9fRl9WRVJTSU9OXzEpKSkKPiA+ID4+Pj4+Pj4+PiArwqDCoMKgwqDC oMKgwqAgcmV0dXJuIC1FSU5WQUw7Cj4gPiA+Pj4+Pj4+Pj4gKwo+ID4gPj4+Pj4+Pj4+ICDCoMKg wqDCoMKgwqDCoCB2ZGV2LT5mZWF0dXJlc192YWxpZCA9IHRydWU7Cj4gPiA+Pj4+Pj4+Pj4gIMKg wqDCoMKgwqDCoMKgwqDCoMKgwqAgcmV0dXJuIG9wcy0+c2V0X2ZlYXR1cmVzKHZkZXYsIGZlYXR1 cmVzKTsKPiA+ID4+Pj4+Pj4+PiAgwqDCoMKgIH0KPiA+ID4+Pj4+Pj4+PiAtLQo+ID4gPj4+Pj4+ Pj4+IDIuMjUuMQo+ID4gCj4gPiAKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fClZpcnR1YWxpemF0aW9uIG1haWxpbmcgbGlzdApWaXJ0dWFsaXphdGlvbkBs aXN0cy5saW51eC1mb3VuZGF0aW9uLm9yZwpodHRwczovL2xpc3RzLmxpbnV4Zm91bmRhdGlvbi5v cmcvbWFpbG1hbi9saXN0aW5mby92aXJ0dWFsaXphdGlvbg== 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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C0F94C433B4 for ; Wed, 12 May 2021 07:53:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B03E613BA for ; Wed, 12 May 2021 07:53:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230230AbhELHzD (ORCPT ); Wed, 12 May 2021 03:55:03 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:32954 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230188AbhELHzB (ORCPT ); Wed, 12 May 2021 03:55:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620806033; 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=oLqmlEuhp9K1sh6b2eNpoKDd7Zyatg2EsHuk0cVSHtk=; b=TQXNadPuQiaQqLydyCdtbcZO4W5V53QmSAENag9M1GRvJ0dkFmHtSPzfgMp5HuzG27c5Ub 4CAqTLxC3WHyEJ/ICYF/VvtzUURiLzr/Hjo4U7qxXIZvp4mFfwNVCOwgOfdrsvq9Xlql1x gZG+N92uDNYc7P264iiWtml4cTZBR/0= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-115-wjZ85ylWM_q98wIPx5OMZw-1; Wed, 12 May 2021 03:53:51 -0400 X-MC-Unique: wjZ85ylWM_q98wIPx5OMZw-1 Received: by mail-wr1-f71.google.com with SMTP id 4-20020adf80040000b029010cab735fdeso9785144wrk.14 for ; Wed, 12 May 2021 00:53:51 -0700 (PDT) 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=oLqmlEuhp9K1sh6b2eNpoKDd7Zyatg2EsHuk0cVSHtk=; b=ZyWtOo1WSQHlLGZQFms3sC4OGeVDyjrdd0mrF5xP7U3lytkatebf6IM1CSLgm5DMt1 dT8ceN7jcvltepml0fQDbNBFenTXko5xXO5xvm0ZH2FE2v01vMKuKosrFlVhc/fmsrHh JPtXgUb+54zRWHtxeqyHYgtauitOJJra2+RKB1kqmL0e2J9x3IUX0QbdLxbsnAu5F9bf hdquBO/mtb0rNjMYLfawe9IY8Y2JggL9CZ9cEOn//v7oGZcr+jDs2nuSLf9Q6VopCJmA gLola0I397EKQ1Llt/yi3yc6FO2wEBvMGlM6tp8k4tsw/BOaw+TZJb8r3N95CcY7GRPL xCkw== X-Gm-Message-State: AOAM531OMsNAcCTFm7iiMzDfRY8Cxuq6dUKRoli9CRyylwWclmD3tQyt FJBx9qDRbRVyhATTAcvuZpx/4hXd6OCdJaORh0VeSWq1ra1tO/a3ypA2p6SyR7SPIvyj2+gIE+T UssVf1nLnTaKf19hD7IJsRgCy X-Received: by 2002:a5d:6687:: with SMTP id l7mr44251687wru.235.1620806030327; Wed, 12 May 2021 00:53:50 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzWcYC1ZJV5ndKMfy0hWhlyn1mCsM2dWyCgry1CQpLkZu4SNNu5gsMBIrowg+nFlYrSK1Mh7g== X-Received: by 2002:a5d:6687:: with SMTP id l7mr44251663wru.235.1620806030104; Wed, 12 May 2021 00:53:50 -0700 (PDT) Received: from redhat.com ([2a10:8004:640e:0:d1db:1802:5043:7b85]) by smtp.gmail.com with ESMTPSA id r2sm31252563wrv.39.2021.05.12.00.53.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 May 2021 00:53:49 -0700 (PDT) Date: Wed, 12 May 2021 03:53:46 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, parav@nvidia.com, elic@nvidia.com, Lingshan Zhu , mapfelba@redhat.com Subject: Re: [RFC PATCH] vdpa: mandate 1.0 device Message-ID: <20210511061740-mutt-send-email-mst@kernel.org> References: <20210408082648.20145-1-jasowang@redhat.com> <20210409115343-mutt-send-email-mst@kernel.org> <42891807-cb24-5352-f8cb-798e9d1a1854@redhat.com> <20210412050730-mutt-send-email-mst@kernel.org> <01918e14-7f7a-abf2-5864-292a32f0233c@redhat.com> <20210421035331-mutt-send-email-mst@kernel.org> <3d5754f3-c012-67ad-5f01-fc16ec53df4e@redhat.com> <529543956.24692551.1620722593826.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <529543956.24692551.1620722593826.JavaMail.zimbra@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 11, 2021 at 04:43:13AM -0400, Jason Wang wrote: > > > ----- 原始邮件 ----- > > > > 在 2021/4/21 下午4:03, Michael S. Tsirkin 写道: > > > On Wed, Apr 21, 2021 at 03:41:36PM +0800, Jason Wang wrote: > > >> 在 2021/4/12 下午5:23, Jason Wang 写道: > > >>> 在 2021/4/12 下午5:09, Michael S. Tsirkin 写道: > > >>>> On Mon, Apr 12, 2021 at 02:35:07PM +0800, Jason Wang wrote: > > >>>>> 在 2021/4/10 上午12:04, Michael S. Tsirkin 写道: > > >>>>>> On Fri, Apr 09, 2021 at 12:47:55PM +0800, Jason Wang wrote: > > >>>>>>> 在 2021/4/8 下午11:59, Michael S. Tsirkin 写道: > > >>>>>>>> On Thu, Apr 08, 2021 at 04:26:48PM +0800, Jason Wang wrote: > > >>>>>>>>> This patch mandates 1.0 for vDPA devices. The goal is to have the > > >>>>>>>>> semantic of normative statement in the virtio > > >>>>>>>>> spec and eliminate the > > >>>>>>>>> burden of transitional device for both vDPA bus and vDPA parent. > > >>>>>>>>> > > >>>>>>>>> uAPI seems fine since all the vDPA parent mandates > > >>>>>>>>> VIRTIO_F_ACCESS_PLATFORM which implies 1.0 devices. > > >>>>>>>>> > > >>>>>>>>> For legacy guests, it can still work since Qemu will mediate when > > >>>>>>>>> necessary (e.g doing the endian conversion). > > >>>>>>>>> > > >>>>>>>>> Signed-off-by: Jason Wang > > >>>>>>>> Hmm. If we do this, don't we still have a problem with > > >>>>>>>> legacy drivers which don't ack 1.0? > > >>>>>>> Yes, but it's not something that is introduced in this > > >>>>>>> commit. The legacy > > >>>>>>> driver never work ... > > >>>>>> My point is this neither fixes or prevents this. > > >>>>>> > > >>>>>> So my suggestion is to finally add ioctls along the lines > > >>>>>> of PROTOCOL_FEATURES of vhost-user. > > >>>>>> > > >>>>>> Then that one can have bits for legacy le, legacy be and modern. > > >>>>>> > > >>>>>> BTW I looked at vhost-user and it does not look like that > > >>>>>> has a solution for this problem either, right? > > >>>>> Right. > > >>>>> > > >>>>> > > >>>>>>>> Note 1.0 affects ring endianness which is not mediated in QEMU > > >>>>>>>> so QEMU can't pretend to device guest is 1.0. > > >>>>>>> Right, I plan to send patches to do mediation in the > > >>>>>>> Qemu to unbreak legacy > > >>>>>>> drivers. > > >>>>>>> > > >>>>>>> Thanks > > >>>>>> I frankly think we'll need PROTOCOL_FEATURES anyway, it's > > >>>>>> too useful ... > > >>>>>> so why not teach drivers about it and be done with it? You > > >>>>>> can't emulate > > >>>>>> legacy on modern in a cross endian situation because of vring > > >>>>>> endian-ness ... > > >>>>> So the problem still. This can only work when the hardware can support > > >>>>> legacy vring endian-ness. > > >>>>> > > >>>>> Consider: > > >>>>> > > >>>>> 1) the leagcy driver support is non-normative in the spec > > >>>>> 2) support a transitional device in the kenrel may requires the > > >>>>> hardware > > >>>>> support and a burden of kernel codes > > >>>>> > > >>>>> I'd rather simply drop the legacy driver support > > >>>> My point is this patch does not drop legacy support. It merely mandates > > >>>> modern support. > > >>> > > >>> I am not sure I get here. This patch fails the set_feature if VERSION_1 > > >>> is not negotiated. This means: > > >>> > > >>> 1) vDPA presents a modern device instead of transitonal device > > >>> 2) legacy driver can't be probed > > >>> > > >>> What I'm missing? > > >> > > >> Hi Michael: > > >> > > >> Do you agree to find the way to present modern device? We need a > > >> conclusion > > >> to make the netlink API work to move forward. > > >> > > >> Thanks > > > I think we need a way to support legacy with no data path overhead. qemu > > > setting VERSION_1 for a legacy guest affects the ring format so it does > > > not really work. This seems to rule out emulating config space entirely > > > in userspace. > > > > > > So I'd rather drop the legacy support in this case. It never work for > > vDPA in the past and virtio-vDPA doesn't even need that. Note that > > ACCESS_PLATFORM is mandated for all the vDPA parents right now which > > implies modern device and LE. I wonder what's the value for supporting > > legacy in this case or do we really encourage vendors to ship card with > > legacy support (e.g endian support in the hardware)? > > Hi Michael: > > Any thoughts on this approach? > > My understanding is that dropping legacy support will simplify a lot of stuffs. > > Thanks So basically the main condition is that strong memory barriers aren't needed for virtio, smp barriers are enough. Are there architectures besides x86 (where it's kind of true - as long as one does not use non-temporals) where that is true? If all these architectures are LE then we don't need to worry about endian support in the hardware. In other words I guess yes we could have qemu limit things to x86 and then just pretend to the card that it's virtio 1. So endian-ness we can address. Problem is virtio 1 has effects beyond this. things like header size with mergeable buffers off for virtio net. So I am inclined to say let us not do the "pretend it's virtio 1" game in qemu. Let us be honest to the card about what happens. But if you want to limit things to x86 either in kernel or in qemu, that's ok by me. > > > > > > > > > > > So I think we should add an ioctl along the lines of > > > protocol features. Then I think we can reserve feature bits > > > for config space format: legacy LE, legacy BE, modern. > > > > > > We had VHOST_SET_VRING_ENDIAN but this will complicates both the vDPA > > parent and management. What's more important, legacy behaviour is not > > restrictied by the spec. > > > > > > > > > > Querying the feature bits will provide us with info about > > > what does the device support. Acking them will tell device > > > what does guest need. > > > > > > I think this can work, but I wonder how much we can gain from such > > complexitiy. > > > > Thanks > > > > > > > > > > > > > > > > > > > > > >>> > > >>>>> to have a simple and easy > > >>>>> abstarction in the kenrel. For legacy driver in the guest, > > >>>>> hypervisor is in > > >>>>> charge of the mediation: > > >>>>> > > >>>>> 1) config space access endian conversion > > >>>>> 2) using shadow virtqueue to change the endian in the vring > > >>>>> > > >>>>> Thanks > > >>>> I'd like to avoid shadow virtqueue hacks if at all possible. > > >>>> Last I checked performance wasn't much better than just emulating > > >>>> virtio in software. > > >>> > > >>> I think the legacy driver support is just a nice to have. Or do you see > > >>> any value to that? I guess for mellanox and intel, only modern device is > > >>> supported in the hardware. > > >>> > > >>> Thanks > > >>> > > >>> > > >>>>>>>> > > >>>>>>>> > > >>>>>>>>> --- > > >>>>>>>>>     include/linux/vdpa.h | 6 ++++++ > > >>>>>>>>>     1 file changed, 6 insertions(+) > > >>>>>>>>> > > >>>>>>>>> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h > > >>>>>>>>> index 0fefeb976877..cfde4ec999b4 100644 > > >>>>>>>>> --- a/include/linux/vdpa.h > > >>>>>>>>> +++ b/include/linux/vdpa.h > > >>>>>>>>> @@ -6,6 +6,7 @@ > > >>>>>>>>>     #include > > >>>>>>>>>     #include > > >>>>>>>>>     #include > > >>>>>>>>> +#include > > >>>>>>>>>     /** > > >>>>>>>>>      * vDPA callback definition. > > >>>>>>>>> @@ -317,6 +318,11 @@ static inline int > > >>>>>>>>> vdpa_set_features(struct vdpa_device *vdev, u64 > > >>>>>>>>> features) > > >>>>>>>>>     { > > >>>>>>>>>             const struct vdpa_config_ops *ops = vdev->config; > > >>>>>>>>> +        /* Mandating 1.0 to have semantics of > > >>>>>>>>> normative statements in > > >>>>>>>>> +         * the spec. */ > > >>>>>>>>> +        if (!(features & BIT_ULL(VIRTIO_F_VERSION_1))) > > >>>>>>>>> +        return -EINVAL; > > >>>>>>>>> + > > >>>>>>>>>         vdev->features_valid = true; > > >>>>>>>>>             return ops->set_features(vdev, features); > > >>>>>>>>>     } > > >>>>>>>>> -- > > >>>>>>>>> 2.25.1 > > > >