Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754286AbaDVSwV (ORCPT ); Tue, 22 Apr 2014 14:52:21 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53105 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750888AbaDVSwU (ORCPT ); Tue, 22 Apr 2014 14:52:20 -0400 Message-ID: <5356BA2F.2030007@zytor.com> Date: Tue, 22 Apr 2014 11:51:27 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Brian Gerst CC: Andrew Lutomirski , Linus Torvalds , Borislav Petkov , "H. Peter Anvin" , Linux Kernel Mailing List , Ingo Molnar , Alexander van Heukelum , Konrad Rzeszutek Wilk , Boris Ostrovsky , Arjan van de Ven , Alexandre Julliard , Andi Kleen , Thomas Gleixner Subject: Re: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE* References: <20140422112312.GB15882@pd.tnic> <20140422144659.GF15882@pd.tnic> <53569467.1030809@zytor.com> <5356A70A.5090907@zytor.com> <5356AF9F.4010301@zytor.com> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/22/2014 11:17 AM, Brian Gerst wrote: >> >> That is the entry condition that we have to deal with. The fact that >> the switch to the IST is unconditional is what makes ISTs hard to deal with. > > Right, that is why you switch away from the IST as soon as possible, > copying the data that is already pushed there to another stack so it > won't be overwritten by a recursive fault. > That simply will not work if you can take a #GP due to the "safe" MSR functions from NMI and #MC context, which would be my main concern. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/