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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED 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 6D0CBC43381 for ; Thu, 21 Mar 2019 18:19:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4598521874 for ; Thu, 21 Mar 2019 18:19:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553192355; bh=qrn9WlnahAiB++hZpQegMOCEejvUTf+ltmPBNYEB17k=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=bnntUJXvalffoBhZk7PzhxR7NbKmE76MfFGAfffGvsy5b8uI6TzG1ZvhFdSpSkep4 kkGZkbeg9I3GQuqxJeBJ1kdA6GIlsHrI9ZV89Ob0CjU3HAfRWuevtc0T9xsnmUcN1n iF6VwweWmrLzEZaLu9XoBtsmFBwhS4JWSLfVtDTg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728657AbfCUSTO (ORCPT ); Thu, 21 Mar 2019 14:19:14 -0400 Received: from mail-lf1-f66.google.com ([209.85.167.66]:46584 "EHLO mail-lf1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728635AbfCUSTN (ORCPT ); Thu, 21 Mar 2019 14:19:13 -0400 Received: by mail-lf1-f66.google.com with SMTP id r25so1706953lfn.13 for ; Thu, 21 Mar 2019 11:19:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=+ZotGGbR6yKUxolSVIlwFT+5L+D2RvzwYtgbxe+84DY=; b=AOPzLDXyE7w8u7Cy2G0FYuMj890Yl8kIy7jBQtaiayt5QYtmXv8Ul0U7TGDFFhP9Ex AmtYVorXJ6m428x7t8q9PwwtdTTw6jlTfodumBLqZO0KrM2pdkYnd+faxDarSYc9GJcO LO0YTdbE5SaLXpOEUptqD20r02uEYraaovBs8= 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=+ZotGGbR6yKUxolSVIlwFT+5L+D2RvzwYtgbxe+84DY=; b=SMrWkd/drAl95oRaCnge5IO8D5/2eXtWKh3a0+f0LrtzDusjeZbZi60c0trVN0i48v 2eYo27F2qbAry0NPMA42+C4hntBnTIO2pK6PSo8jpTtFsQVkKpoECNO7Pir32LPIbbfw TeeSwskAV6qG1/XUwq3nDkgIIQQ+tGIs+qA07dZy0aUebAcHiawVSEFTpp0dJN/QnhWa 5jofjRBnWHckKITqQje9zGMhaVTq+pomYg7Lkkw6UIF+OqjG1W7Q9otaoc7U2xZY9xwc IpnCR/UU6ae+8zkuR7TVJOvdRYrGVFLAYyNSOFgIcAXFDKRWPs170CawYcbE0tnlVEpW 9UDQ== X-Gm-Message-State: APjAAAWw/Hvou4jEcmgDrEHt3QskewYuy9FJpO9NQha/WdrQ2SSkY4Hb 80G/b2lg4AKWPsDawVJ7EuApvXJzqSc= X-Google-Smtp-Source: APXvYqzTNXD9Qh46eM0T45FBkZH9WfC7h0CtCfhIu9Xy2yTlHVU8fDS3OcdSb5Mq2TV6dCIUQpjSBg== X-Received: by 2002:ac2:514a:: with SMTP id q10mr2757788lfd.17.1553192350610; Thu, 21 Mar 2019 11:19:10 -0700 (PDT) Received: from mail-lf1-f44.google.com (mail-lf1-f44.google.com. [209.85.167.44]) by smtp.gmail.com with ESMTPSA id u18sm1096653lfd.15.2019.03.21.11.19.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 21 Mar 2019 11:19:09 -0700 (PDT) Received: by mail-lf1-f44.google.com with SMTP id a6so5301110lfl.5 for ; Thu, 21 Mar 2019 11:19:09 -0700 (PDT) X-Received: by 2002:ac2:4424:: with SMTP id w4mr2768854lfl.148.1553192349132; Thu, 21 Mar 2019 11:19:09 -0700 (PDT) MIME-Version: 1.0 References: <20190320221534.165ab87b@oasis.local.home> <20190321083317.GL6058@hirez.programming.kicks-ass.net> <20190321090241.GL6521@hirez.programming.kicks-ass.net> <20190321104517.GM6521@hirez.programming.kicks-ass.net> <20190321093242.4a948198@gandalf.local.home> <20190321172203.GS5996@hirez.programming.kicks-ass.net> In-Reply-To: From: Linus Torvalds Date: Thu, 21 Mar 2019 11:18:53 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC][PATCH] tracing/x86: Save CR2 before tracing irqsoff on error_entry To: Andy Lutomirski Cc: Peter Zijlstra , Steven Rostedt , Juergen Gross , LKML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Joel Fernandes , He Zhe Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 21, 2019 at 11:05 AM Andy Lutomirski wrote: > > In the long run, I think the right solution is to rewrite even more of > this mess in C. We really ought to be able to put the IRQ flag > tracing and the context tracking into C code. Tangentially about this long run thing - can we start discussing just dropping PV mode entirely in the long run? Or even not-so-long run? What are the pressing advantages of paravirt these days? Because I can point to a lot of pressing _disadvantages_, and not all of them are about more complex code as shown by this patch... Linus