Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754905AbbKSMIY (ORCPT ); Thu, 19 Nov 2015 07:08:24 -0500 Received: from mx2.suse.de ([195.135.220.15]:47563 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750782AbbKSMIX (ORCPT ); Thu, 19 Nov 2015 07:08:23 -0500 Date: Thu, 19 Nov 2015 13:08:09 +0100 From: Borislav Petkov To: Andy Lutomirski Cc: Boris Ostrovsky , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , David Vrabel , Konrad Rzeszutek Wilk , Andrew Lutomirski , "linux-kernel@vger.kernel.org" , "xen-devel@lists.xenproject.org" , Linux Virtualization Subject: Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Message-ID: <20151119120809.GC5953@pd.tnic> References: <1447877179-2775-1-git-send-email-boris.ostrovsky@oracle.com> <1447877179-2775-2-git-send-email-boris.ostrovsky@oracle.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 Content-Length: 785 Lines: 24 On Wed, Nov 18, 2015 at 12:21:56PM -0800, Andy Lutomirski wrote: > Could we make this a little less subtle: > > ALTERNATIVE "testl %eax, %eax; lz .Lsyscall_32_done", "jmp > .Lsyscasll_32_done", X86_FEATURE_XENPV > > Borislav, what do you think? I don't mind either. I would've said your version doesn't touch %eax so the result in there might be useful for callers but all paths do overwrite it, AFAICT. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) -- -- 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/