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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 60B24C64EB4 for ; Fri, 30 Nov 2018 20:59:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E04B20863 for ; Fri, 30 Nov 2018 20:59:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hsb1y5qK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1E04B20863 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726752AbeLAIKY (ORCPT ); Sat, 1 Dec 2018 03:10:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:37374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725867AbeLAIKY (ORCPT ); Sat, 1 Dec 2018 03:10:24 -0500 Received: from mail-wm1-f54.google.com (mail-wm1-f54.google.com [209.85.128.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A1CC821479 for ; Fri, 30 Nov 2018 20:59:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543611590; bh=dklhLqSh/R3eawAshrdGCTAzouty0hE7j0furIEfWGM=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=hsb1y5qKkN4Q39SDlL0Ot+tNE3SGupkh0uvX/i4BHmbq/iUg5dHQ5IdYTHnwvX9p1 wPyu++1o4NKRoGRxlVoc6mmup5vHLwXttrvgvprfD7lTwn7Qn99mu7nELLkeepbF9x 7Fv/ZvPo93q4uEmK4CSu1Pp+r5rB7DeHUfrfHjRo= Received: by mail-wm1-f54.google.com with SMTP id n133so248572wmd.4 for ; Fri, 30 Nov 2018 12:59:50 -0800 (PST) X-Gm-Message-State: AA+aEWZJHUnzFcAN86tXF/ZzMj8h7DD/xV2bOOWqURVqDC8fAZlHbza1 7DH6ZivcTloMthZWppwg96UZp9daDH7X0PmSmhGc0A== X-Google-Smtp-Source: AFSGD/U+PSBW/L7TjC0EmDoLwX5Ze/kiSCujzK9KU3HVLgQgBnAMbm19mauAvcb+lDCik/iMFLMijMwC9qNFn8d0AEE= X-Received: by 2002:a1c:b1d5:: with SMTP id a204mr284175wmf.32.1543611589060; Fri, 30 Nov 2018 12:59:49 -0800 (PST) MIME-Version: 1.0 References: <20181129124404.2fe55dd0@gandalf.local.home> <20181129125857.75c55b96@gandalf.local.home> <20181129134725.6d86ade6@gandalf.local.home> <20181129202452.56f4j2wdct6qbaqo@treble> <20181130183917.hxmti5josgq4clti@treble> <20181130152852.456ce379@gandalf.local.home> In-Reply-To: <20181130152852.456ce379@gandalf.local.home> From: Andy Lutomirski Date: Fri, 30 Nov 2018 12:59:36 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64 To: Steven Rostedt Cc: Andrew Lutomirski , Linus Torvalds , Josh Poimboeuf , Peter Zijlstra , X86 ML , LKML , Ard Biesheuvel , Ingo Molnar , Thomas Gleixner , Masami Hiramatsu , Jason Baron , Jiri Kosina , David Laight , Borislav Petkov , julia@ni.com, jeyu@kernel.org, "H. Peter Anvin" 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 Fri, Nov 30, 2018 at 12:28 PM Steven Rostedt wrote: > > On Fri, 30 Nov 2018 12:18:33 -0800 > Andy Lutomirski wrote: > > > Or we could replace that IPI with x86's bona fide serialize-all-cpus > > primitive and then we can just retry instead of emulating. It's a > > piece of cake -- we just trigger an SMI :) /me runs away. > > I must have fallen on my head one too many times, because I really like > the idea of synchronizing all the CPUs with an SMI! (If that's even > possible). The IPI's that are sent are only to force smp_mb() on all > CPUs. Which should be something an SMI could do. > > /me runs after Andy According to the SDM, you can program the APIC ICR to request an SMI. It's not remotely clear to me what will happen if we do this. For all I know, the SMI handler will explode and the computer will catch fire. PeterZ?