From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751055AbdLaOOS (ORCPT <rfc822;w@1wt.eu>);
        Sun, 31 Dec 2017 09:14:18 -0500
Received: from Galois.linutronix.de ([146.0.238.70]:35507 "EHLO
        Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1750936AbdLaOOR (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Sun, 31 Dec 2017 09:14:17 -0500
Date: Sun, 31 Dec 2017 15:14:12 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
cc: linux-kernel <linux-kernel@vger.kernel.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@suse.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Hugh Dickins <hughd@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: Review of KPTI patchset
In-Reply-To: <513331052.45894.1514729355641.JavaMail.zimbra@efficios.com>
Message-ID: <alpine.DEB.2.20.1712311513230.1899@nanos>
References: <2080549061.45775.1514659556107.JavaMail.zimbra@efficios.com> <alpine.DEB.2.20.1712302043070.1899@nanos> <1311401854.45816.1514666587545.JavaMail.zimbra@efficios.com> <alpine.DEB.2.20.1712302232320.1899@nanos>
 <513331052.45894.1514729355641.JavaMail.zimbra@efficios.com>
User-Agent: Alpine 2.20 (DEB 67 2015-01-07)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
X-Linutronix-Spam-Score: -1.0
X-Linutronix-Spam-Level: -
X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required,  ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Sun, 31 Dec 2017, Mathieu Desnoyers wrote:
> > Granted, it's not obvious and ideally we convert those this_cpu_read/writes
> > to __this_cpu_read/writes() to get the immediate fail reported on the first
> > access.
> 
> Indeed, if this function is expected to be called from non-preempt context,
> the __this_cpu_*() would be appropriate.
> 
> Moreover, clear_asid_other() could use a "static" definition, given that it's only ever
> used from arch/x86/mm/tlb.c:choose_new_asid(). Otherwise nothing prevents other users
> from unrelated areas of the kernel from calling it, and then we should document that
> preemption needs to be disabled around its invocation.
> 
> While we are there (discussing preemption and migration), I'm puzzled about the
> preempt_disable/enable in __native_flush_tlb(). First, it should cover the
> invalidate_user_asid() call too. Also, if the __ prefixed functions in this header

You're late to that discussion. That has been fixed already....

Thanks,

	tglx