From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754881AbbG3Htr (ORCPT ); Thu, 30 Jul 2015 03:49:47 -0400 Received: from mail.skyhub.de ([78.46.96.112]:45944 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754776AbbG3Htp (ORCPT ); Thu, 30 Jul 2015 03:49:45 -0400 Date: Thu, 30 Jul 2015 09:49:43 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: Peter Zijlstra , Steven Rostedt , "security@kernel.org" , X86 ML , Sasha Levin , linux-kernel@vger.kernel.org, Konrad Rzeszutek Wilk , Boris Ostrovsky , Andrew Cooper , Jan Beulich , xen-devel , stable@vger.kernel.org Subject: Re: [PATCH v5 2/4] x86/ldt: Make modify_ldt synchronous Message-ID: <20150730074943.GC8984@nazgul.tnic> References: <1f1e8e0367408585694132a0e8693d157959ce30.1438061139.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1f1e8e0367408585694132a0e8693d157959ce30.1438061139.git.luto@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 27, 2015 at 10:29:39PM -0700, Andy Lutomirski wrote: > modify_ldt has questionable locking and does not synchronize > threads. Improve it: redesign the locking and synchronize all > threads' LDTs using an IPI on all modifications. > > This will dramatically slow down modify_ldt in multithreaded > programs, but there shouldn't be any multithreaded programs that > care about modify_ldt's performance in the first place. > > Cc: stable@vger.kernel.org > Signed-off-by: Andy Lutomirski I've stared a lot at this one these days, I guess a Reviewed-by: Borislav Petkov is in order. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. --