From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752720AbbC1JoV (ORCPT ); Sat, 28 Mar 2015 05:44:21 -0400 Received: from mail.skyhub.de ([78.46.96.112]:39715 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751213AbbC1JoT (ORCPT ); Sat, 28 Mar 2015 05:44:19 -0400 Date: Sat, 28 Mar 2015 10:42:27 +0100 From: Borislav Petkov To: Linus Torvalds Cc: Andy Lutomirski , Denys Vlasenko , "linux-kernel@vger.kernel.org" , X86 ML , Ingo Molnar Subject: Re: ia32_sysenter_target does not preserve EFLAGS Message-ID: <20150328094226.GC17284@pd.tnic> References: <5515686B.3080204@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit 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 Fri, Mar 27, 2015 at 01:09:34PM -0700, Linus Torvalds wrote: > I think AMD documented that the sti "interrupt shadow" shadows even > NMI. Hmm, official docs says this: "15.21.5 Interrupt Shadows The x86 architecture defines the notion of an interrupt shadow—a single-instruction window during which interrupts are not recognized. For example, the instruction after an STI instruction that sets EFLAGS.IF (from zero to one) does not recognize interrupts or certain debug traps." And I think with "interrupts" this means maskable interrupts, i.e. not NMI. STI description itself: "Sets the interrupt flag (IF) in the rFLAGS register to 1, thereby allowing external interrupts received on the INTR input. Interrupts received on the non-maskable interrupt (NMI) input are not affected by this instruction." but there might be some other documentation which I cannot find right now. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. --