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 ED22AC433EF for ; Fri, 22 Jul 2022 17:24:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233965AbiGVRYL (ORCPT ); Fri, 22 Jul 2022 13:24:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235739AbiGVRYB (ORCPT ); Fri, 22 Jul 2022 13:24:01 -0400 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7271A7B7A2 for ; Fri, 22 Jul 2022 10:23:54 -0700 (PDT) Received: by mail-pg1-x52e.google.com with SMTP id 12so4716382pga.1 for ; Fri, 22 Jul 2022 10:23:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=nP/kZp+cfU+PzA9FUjazEG7/eYrubq8X263Q4O4hdGA=; b=d1uA3R0qq8joJKG5RNV6d/UBGTRfMTvqMP6O7YtvO5p85K2pjIsoI4Zz1VKX4Ak519 QCGffbe+j3tWqxDWOvpLMu6q3LIkT//K257CkgOccMcDegdi2E2JgmBBLLeybYGxUOd3 59LGK7aCNaC7hB8xqLJsH6bqn4KBqOQ+N46BE+0VMs5tIk6a3jn8dDwV4w/RWViGhKjc 1+xVI6W1F8J0r9ipDTvNx/Z0w0jfVhmz2HTltC8T4nG1tr/9diqHK/IbyuF1I1gwZtJv T8XC8FvWkYORTqGvmx92kSnLMH2fbZ3BvsynLr5cr4bHmX0Q78OP/aD75I+2QOxYDhMR OK+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=nP/kZp+cfU+PzA9FUjazEG7/eYrubq8X263Q4O4hdGA=; b=KZZcywPutstOrpfzNxTjeAisoN3jlz3DMzW7o7D6bG8acxK7wjLwcq2vDEHXNmnM3Q 3N+yzAtCgVjxYMsFUn7un+wwKbjOENQSJb9Cskh1ZYbl1q/CrQUXQ012HKtLTTrk2mwD wL/b803eQApiJPppUFucqECY26NLUk+cv5103Z1cwFnHhxN2+urcnE6g+ZEoUQICE3VR JKiclpfSxoesfoIuZvmKBv9VFoO2Xq7m0S5lS4Q4n7x3ImpTKlxDy3aPdpYvEXLmLCcx 9sBJ+k0p/AOxswWiM4NOIV9WCbJbYJqsS8vtCeuVdDdmhX9hWS/nxsnVvZZI7yknqVRr dvsw== X-Gm-Message-State: AJIora/p3ZttQH8UeRIbbdLta4qa3vJ6SIjRTXVRHkvhBzbgIUdCRsCv TyC6BI9EX1d6V7JSejAezLbAOg== X-Google-Smtp-Source: AGRyM1uj5dABQna8UMODRfNQ6r1Z8LffiMru2fxqxcgGmeM9Ao43oJ9OhYnmZuxsnSMMweKJJVpbAw== X-Received: by 2002:a63:fc14:0:b0:419:d6c0:c79e with SMTP id j20-20020a63fc14000000b00419d6c0c79emr659961pgi.493.1658510633709; Fri, 22 Jul 2022 10:23:53 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id p27-20020a63951b000000b003fbfe88be17sm3770452pgd.24.2022.07.22.10.23.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Jul 2022 10:23:53 -0700 (PDT) Date: Fri, 22 Jul 2022 17:23:49 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, oliver.upton@linux.dev Subject: Re: [PATCH] Revert "KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled" Message-ID: References: <20220722104329.3265411-1-pbonzini@redhat.com> <0f8dde12-576b-1579-38c9-496306aeeb81@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0f8dde12-576b-1579-38c9-496306aeeb81@redhat.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jul 22, 2022, Paolo Bonzini wrote: > On 7/22/22 17:27, Sean Christopherson wrote: > > > So revert it, at the potential cost > > > of breaking L1s with a 6 year old kernel. > > I would further qualify this with "breaking L1s with an_unpatched_ 6 year old > > kernel". That fix was tagged for stable and made it way to at least the 4.9 and > > 4.4 LTS releases. > > > > Well, there _are_ people that use very old kernels and keep them up-to-date > with fixes for only critical CVEs (for example by, ehm, paying my employer > to do so). Heh, I'm sure that's a winning strategy. > But still it's way way unlikely for them to be used as L1 in a nested setup, > whether on their own hardware or in the cloud. > > I pushed everything to kvm/queue, but depending on what you post it may be > deferred to 5.21. Can you drop the PERF_GLOBAL_CTRL revert? I figured out how to achieve what you intended, but in a more robust (and IMO more logical) manner. If you don't drop it before I concoct the series, I'll just include a throwaway patch to revert it.