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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 BDA35C2D0E4 for ; Fri, 20 Nov 2020 23:54:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77A6F2240C for ; Fri, 20 Nov 2020 23:54:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="mdmSYKuo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728197AbgKTXx7 (ORCPT ); Fri, 20 Nov 2020 18:53:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727248AbgKTXx7 (ORCPT ); Fri, 20 Nov 2020 18:53:59 -0500 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4095C061A04 for ; Fri, 20 Nov 2020 15:53:58 -0800 (PST) Received: by mail-pf1-x443.google.com with SMTP id c66so9416205pfa.4 for ; Fri, 20 Nov 2020 15:53:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/9QmQzu0viMhe1+E2AuJjw4yABAqeWJl/tuV7zSeb+U=; b=mdmSYKuoJmPQiSSZKAXRHrhaYfKRSQA9hE/wfOsOCkhwS+3+67n+lejlrZY4HtZfn/ a2ORoKHB2+RW61Vt9T9zrAHoM1RsQbsuWV47pPf93KFSlEHy1Tfio9hzAUE4BkPNXx+I YITKk0YEENSGCNohJ36jZOmfNM0ry/U9Rv8sczK8LJbtzspnCR2SDBjJ4zad2AR6UovQ Szo2WkElnVp3Pq1aFadmc5JzwZozrsYu/68ODALQuad6JmMLMpwoXKqfBusvVuclgTF+ rSwKmAgZg2oXKzT79ocvKhy7QjjLbUii5XJDdT+bt/WFOVYQqnt9FCLWzuGSaXf0zzOP TH/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=/9QmQzu0viMhe1+E2AuJjw4yABAqeWJl/tuV7zSeb+U=; b=EwqHJSUXK+kIOsI89Dk3J4E4QjHTkV7/P+ol5XiDRF+ZmvOJg+XEQIMLenLiIIax6z GrUmqVI9aBaZrkArVTL/dhUHA8QDRTA5njzMB+imVRqX2yABGKnVJmdozHB3i97g6bDg m8cL9WvlTAbPkODB1Lmb/9+KGCPJylY8T3XTxppUv+I7D6hsMFdj4doQ7YrJlbW2MU0l GOfplpGpGWr64Wu5x17oNYMWOB/MeiUaQSY/GSzsfZFfGW/uDpHWLY1YokUu+r0yJVZE 4aPBvQf71M7ESal/k1P3Jw4V08dMjgXuNDVHIvDMVtEj6nzo+jBZ9b+Kdc2Jpw6O3Rt0 mNcg== X-Gm-Message-State: AOAM5306f8MabsSyudWDhdYz4+a7g4h+n9veFdfIEGtpwUpGeqI5oFr8 7IrVMz33Mh2Tc1/OskveUSGbZXnzoZFLyKbZY8s2ig== X-Google-Smtp-Source: ABdhPJy2DGSHmfFcAh4bM/VKta4IGQmsyfxYSHlfpKnMfeL7FrQ+44E3UgsHXg0jgCwAXeN0PaduNYVMcO8diBSDC4k= X-Received: by 2002:a17:90a:6b04:: with SMTP id v4mr13286585pjj.101.1605916438104; Fri, 20 Nov 2020 15:53:58 -0800 (PST) MIME-Version: 1.0 References: <20201118220731.925424-1-samitolvanen@google.com> In-Reply-To: From: Nick Desaulniers Date: Fri, 20 Nov 2020 15:53:45 -0800 Message-ID: Subject: Re: [PATCH v7 00/17] Add support for Clang LTO To: Ard Biesheuvel Cc: Sami Tolvanen , Masahiro Yamada , Steven Rostedt , Will Deacon , Josh Poimboeuf , Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , clang-built-linux , Kernel Hardening , linux-arch , Linux ARM , Linux Kbuild mailing list , LKML , PCI , Alistair Delva Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Fri, Nov 20, 2020 at 3:30 PM Ard Biesheuvel wrote: > > On Fri, 20 Nov 2020 at 21:19, Nick Desaulniers wrote: > > > > On Fri, Nov 20, 2020 at 2:30 AM Ard Biesheuvel wrote: > > > > > > On Thu, 19 Nov 2020 at 00:42, Nick Desaulniers wrote: > > > > > > > > Thanks for continuing to drive this series Sami. For the series, > > > > > > > > Tested-by: Nick Desaulniers > > > > > > > > I did virtualized boot tests with the series applied to aarch64 > > > > defconfig without CONFIG_LTO, with CONFIG_LTO_CLANG, and a third time > > > > with CONFIG_THINLTO. If you make changes to the series in follow ups, > > > > please drop my tested by tag from the modified patches and I'll help > > > > re-test. Some minor feedback on the Kconfig change, but I'll post it > > > > off of that patch. > > > > > > > > > > When you say 'virtualized" do you mean QEMU on x86? Or actual > > > virtualization on an AArch64 KVM host? > > > > aarch64 guest on x86_64 host. If you have additional configurations > > that are important to you, additional testing help would be > > appreciated. > > > > Could you run this on an actual phone? Or does Android already ship > with this stuff? By `this`, if you mean "the LTO series", it has been shipping on Android phones for years now, I think it's even required in the latest release. If you mean "the LTO series + mainline" on a phone, well there's the android-mainline of https://android.googlesource.com/kernel/common/, in which this series was recently removed in order to facilitate rebasing Android's patches on ToT-mainline until getting the series landed upstream. Bit of a chicken and the egg problem there. If you mean "the LTO series + mainline + KVM" on a phone; I don't know the precise state of aarch64 KVM and Android (Will or Marc would know). We did experiment recently with RockPI's for aach64 KVM, IIRC; I think Android is tricky as it still requires A64+A32/T32 chipsets, Alistair would know more. Might be interesting to boot a virtualized (or paravirtualized?) guest built with LTO in a host built with LTO for sure, but I don't know if we have tried that yet (I think we did try LTO guests of android kernels, but I think they were on the stock RockPI host BSP image IIRC). > > > The distinction is important here, given the potential impact of LTO > > > on things that QEMU simply does not model when it runs in TCG mode on > > > a foreign host architecture. -- Thanks, ~Nick Desaulniers