Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758145AbaGWPXP (ORCPT ); Wed, 23 Jul 2014 11:23:15 -0400 Received: from mail.skyhub.de ([78.46.96.112]:59759 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752877AbaGWPXO (ORCPT ); Wed, 23 Jul 2014 11:23:14 -0400 Date: Wed, 23 Jul 2014 17:23:11 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: "H. Peter Anvin" , Linus Torvalds , "linux-kernel@vger.kernel.org" , X86 ML Subject: Re: STI architectural question (and lretq -- I'm not even kidding) Message-ID: <20140723152311.GC21707@pd.tnic> References: <20140723104917.GB23102@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 Wed, Jul 23, 2014 at 08:12:32AM -0700, Andy Lutomirski wrote: > How are we supposed to survive two machine checks in rapid succession? > The second will fire as soon as the first one is acked, I imagine. > Unless we switch stacks before acking the MCE, the return address of > the first one will be lost. Oh, that might not fly but in that case the box probably deserves to die anyway. I was adressing what you said earlier: "But here's the problem: what happens if an NMI or MCE happens between the sti and the lretq? I think an MCE just might be okay -- it's not really recoverable anyway." An MC Exception can be recoverable and we can recover. The fact that we raise an exception doesn't always mean we die. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- -- 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/