From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756015AbbCCKG6 (ORCPT ); Tue, 3 Mar 2015 05:06:58 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:25196 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755593AbbCCKG4 (ORCPT ); Tue, 3 Mar 2015 05:06:56 -0500 X-IronPort-AV: E=Sophos;i="5.09,681,1418083200"; d="scan'208";a="240867074" Message-ID: <54F587BD.8010606@citrix.com> Date: Tue, 3 Mar 2015 10:06:53 +0000 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.4.0 MIME-Version: 1.0 To: "Luis R. Rodriguez" , Andrey Ryabinin CC: Jeremy Fitzhardinge , Rusty Russell , "linux-kernel@vger.kernel.org" , Andy Lutomirski , Chris Wright , , Boris Ostrovsky , , Alok Kataria Subject: Re: [Xen-devel] kasan_map_early_shadow() on Xen References: In-Reply-To: Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/03/15 09:40, Luis R. Rodriguez wrote: > Andrey, > > I believe that on Xen we should disable kasan, would like confirmation Why? This is the first of heard of this. > from someone on xen-devel though. Here's the thing though -- if true > -- I'd like to do it *properly*, where *properly* means addressing a > bit of architecture. A simple Kconfig slap seems rather reactive. I'd > like to address a way to properly ensure we don't run into this and > other similar issues in the future. The CR4 shadow issue was another > recent example issue, also introduced via v4.0 [0]. We can't keep > doing this reactively. > > Let's go down the rabbit hole for a bit. HAVE_ARCH_KASAN will be > selected on x86 when: > > if X86_64 && SPARSEMEM_VMEMMAP > > Now Xen should not have SPARSEMEM_VMEMMAP but PVOPs' goal is to enable Why? Again, this is the first I've heard of this as well. FWIW, all the Xen configs we use have SPARSEMEM_VMEMMAP enabled. David > distributions to be able to have a single binary kernels and let the > rest be figured out, so we can't just disable SPARSEMEM_VMEMMAP for > Xen alone, we want to build Xen.. or part of Xen and perhaps keep > SPARSEMEM_VMEMMAP, and only later figure things out. > > How do we do this cleanly and avoid future reactive measures? If the > answer is not upon us, I'd like to at least highlight the issue so > that in case we do come up with something its no surprise PVOPs is > falling short for that single binary pipe dream right now. > > [0] https://lkml.org/lkml/2015/2/23/328 > > Luis > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel >