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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A8D1C32771 for ; Wed, 28 Sep 2022 09:57:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232112AbiI1J5L (ORCPT ); Wed, 28 Sep 2022 05:57:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233483AbiI1J4n (ORCPT ); Wed, 28 Sep 2022 05:56:43 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E41C1EEEB1 for ; Wed, 28 Sep 2022 02:55:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1664358927; 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=Gb2cJ+qaMdaxmKIGMGEE3usUOdY7PjedRhOx/d0j24w=; b=Wjx652WRlQHb/sHed7F6GFWgB/pVqXenjbotKSahsRMMSocjPiwsl+Q3CCnKCslCL0GEZV maNCRZlEAT/saDP1Cg2fJU/kB4bPUNwSGYyPvQLvAB28kgNobyDURKGLDLUm/vYMNdUdKH kPGVVDCUfDZZ+5/yjGqN4mi9TNhiuBw= Received: from mail-ej1-f69.google.com (mail-ej1-f69.google.com [209.85.218.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-194-1qBRVf_8NQy3hVMSf8SjzQ-1; Wed, 28 Sep 2022 05:55:26 -0400 X-MC-Unique: 1qBRVf_8NQy3hVMSf8SjzQ-1 Received: by mail-ej1-f69.google.com with SMTP id hq17-20020a1709073f1100b00782f9d252f4so4579682ejc.11 for ; Wed, 28 Sep 2022 02:55:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date; bh=Gb2cJ+qaMdaxmKIGMGEE3usUOdY7PjedRhOx/d0j24w=; b=Om5JCIOJSkdhY9/lnoauPfwSspJXni7fjFM7jai4mcFEwkMTAJtyy/jvuvReAE19xb swguHyr7WtnSOZAFiJOO8voyp6aJ8vi+rVR7FZGaNBkbcjPrgXI/wAfwFvl/6DEBwrN0 JyOEUSroV0LXglE5CFHCIL2tkDYN+SeOPI0osgMEEXoGXQ0HFoX7/26pJXrhc4Rbt0F9 u3v4Ej6fa/JVs/lxsEi1t8G2uvKKp8v5IPf/+mI10xSB3nf/xCwtSSj8ekMzGfBZNl8U hRWzysZPKr9xbrFhF4/p5Bo1Pf8SlZRblM1nluwwM/8gccceXvfz+lh8yTHr/xwTKMYQ Kucg== X-Gm-Message-State: ACrzQf12zGPmVmAm9fahSgo1xCiNzaKFliFzjg7k+uAzaoFEDRiAftxv Kisovq3SxDs9FG8jo2/KW32v14CQkJ/MFfZk8JXkYDfbaAN1RXRfuXas1OErLQaLFnJu6Nw9jC/ U5vTDxFclr7MtezrkcaEr161E X-Received: by 2002:a05:6402:5489:b0:43b:b935:db37 with SMTP id fg9-20020a056402548900b0043bb935db37mr33111978edb.347.1664358925448; Wed, 28 Sep 2022 02:55:25 -0700 (PDT) X-Google-Smtp-Source: AMsMyM5aoT98C15jrHtWaJSl4x7zl5R0lQTFlQ8XfjPs33lQ63BHlo5MahvDX4rUtn3EeusKpVq9kQ== X-Received: by 2002:a05:6402:5489:b0:43b:b935:db37 with SMTP id fg9-20020a056402548900b0043bb935db37mr33111963edb.347.1664358925220; Wed, 28 Sep 2022 02:55:25 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:2f4b:62da:3159:e077? ([2001:b07:6468:f312:2f4b:62da:3159:e077]) by smtp.googlemail.com with ESMTPSA id j2-20020a17090623e200b0078015cebd8csm2140882ejg.117.2022.09.28.02.55.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Sep 2022 02:55:24 -0700 (PDT) Message-ID: <15291c3f-d55c-a206-9261-253a1a33dce1@redhat.com> Date: Wed, 28 Sep 2022 11:55:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.1 Subject: Re: [PATCH] KVM: x86: disable on 32-bit unless CONFIG_BROKEN Content-Language: en-US To: Maxim Levitsky , Sean Christopherson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: <20220926165112.603078-1-pbonzini@redhat.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/28/22 09:10, Maxim Levitsky wrote: > I also think that outside KVM developers nobody should be using KVM on 32 bit host. > > However for_developement_ I think that 32 bit KVM support is very useful, as it > allows to smoke test the support for 32 bit nested hypervisors, which I do once in a while, > and can even probably be useful to some users (e.g running some legacy stuff in a VM, > which includes a hypervisor, especially to run really legacy OSes / custom bare metal software, > using an old hypervisor) - or in other words, 32 bit nested KVM is mostly useless, but > other 32 bit nested hypervisors can be useful. > > Yes, I can always use an older 32 bit kernel in a guest with KVM support, but as long > as current kernel works, it is useful to use the same kernel on host and guest. Yeah, I would use older 32 bit kernels just like I use RHEL4 to test PIT reinjection. :) But really the ultimate solution to this would be to improve kvm-unit-tests so that we can compile vmx.c and svm.c for 32-bit. Paolo