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 D04F5C433FE for ; Tue, 4 Oct 2022 18:22:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229513AbiJDSWP (ORCPT ); Tue, 4 Oct 2022 14:22:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229451AbiJDSWK (ORCPT ); Tue, 4 Oct 2022 14:22:10 -0400 Received: from mail-oo1-xc36.google.com (mail-oo1-xc36.google.com [IPv6:2607:f8b0:4864:20::c36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46E6458154 for ; Tue, 4 Oct 2022 11:22:09 -0700 (PDT) Received: by mail-oo1-xc36.google.com with SMTP id z9-20020a4a4909000000b0047651b95fbdso9317445ooa.5 for ; Tue, 04 Oct 2022 11:22:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=pjPqPtWhi1XRi39ewNA3ilgZVEPOXvL7Gk41mzKrCKc=; b=qlUzFD59c5iepU8YIIkyWn198JUABfqxyCGoBSEcQyq1q0/EpPAAIDlrbRdAzf/nEV ZG3j4siZlQc3qVQ4MttYi+dagV0zdFz5dzh+CnVoz4ptytRUkiq3C/h1x/T5cpyDgjUL MZTWvN806z0IoQotFx4pJlDwKtxFcByBhcfWZ7aKeEXi6H6WZck6lI/Szs8oMA21zcid 3bLExwLhqelYkCsnfzP1cM8XDWo3ygIMHxwPbOaz5uq9UQYFYW+nl/4GQUaD1x+gcZBB 7RhrtxViMBK4ULtWL+EqGgz9/wpX+hfCZBVzCEaQIZE+Qa2WQg2uttlOAxMXMue/n4kJ cD2Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=pjPqPtWhi1XRi39ewNA3ilgZVEPOXvL7Gk41mzKrCKc=; b=gg62n3Mq4hafW86dcsi1ItTyagvGBke/3UwinSLgFrEYVPPBia5J/W2f8cJz+zWLAB YB0SMEil51U+6Sy+/pR2XI+/xSEoCiOSWt6DbjNqf9/oWtEGE03jeeL3um1hgQk5LvnL s6aAYSda5lyP3WoA9apg9xO2lUOXFAlWW288lb2NtuOrOoOTW2fDmMNR/JoIjULo7hAK /zBUUu7kcfM2+cFofIKThICnYEw7rtLpxsrYmAXXHsA0hhJGA8BEQ4yJ4Cm2wBDgiS11 6mMLYZwM+VaPwgsrMfeSaKoXUEaWfJ0qAZhYbkuuZyz+R4l5+bTbtkiaGfNXlx1o3YZU N0jw== X-Gm-Message-State: ACrzQf2h/iT79Oq3Du8UQ9DtgL1jn2DeHB/DEf0k8VPFBrep2jy/ZAch 85fVA+ng9fGV5DFqwuPFDtA/P4fQ+OIVKTJkDMA7Ag== X-Google-Smtp-Source: AMsMyM4am+nVPEHPqmOdvpPpMnN46oy1DA1DJItnPfIOgT4WdacXo476dek5DVbFcztiC7Kk6fed6vhYc90uIFURkQ0= X-Received: by 2002:a05:6830:2705:b0:659:ebb0:ecad with SMTP id j5-20020a056830270500b00659ebb0ecadmr10055063otu.75.1664907728427; Tue, 04 Oct 2022 11:22:08 -0700 (PDT) MIME-Version: 1.0 References: <547a1203-0339-7ad2-9505-eab027046298@intel.com> In-Reply-To: <547a1203-0339-7ad2-9505-eab027046298@intel.com> From: Jim Mattson Date: Tue, 4 Oct 2022 11:21:57 -0700 Message-ID: Subject: Re: Finish removing MPX from arch/x86? To: Dave Hansen Cc: Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Arjan van de Ven Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 4, 2022 at 10:45 AM Dave Hansen wrote: > > We zapped the userspace MPX ABIs and most of its supporting code in here: > > 45fc24e89b7c ("x86/mpx: remove MPX from arch/x86") > > But, the XSAVE enabling and KVM code were left in place. This let folks > at least keep running guests with MPX. > > It's been a couple of years and I don't think I've had a single person > opine about the loss of MPX. Intel also followed through and there's no > MPX to be found on newer CPUs like my "Tiger Lake" 11th Gen Intel(R) > Core(TM) i7-1165G7. > > Is it time to zap MPX from arch/x86/kvm/? Until Google Cloud retires all of our MPX-capable hardware, we will require MPX support in KVM. Removing that support would leave VMs with MPX enabled in XCR0 with nowhere to go.