From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] Permit -mem-path without sync mmu Date: Mon, 08 Aug 2011 11:24:09 +0300 Message-ID: <4E3F9D29.2000708@redhat.com> References: <1312516970-26606-1-git-send-email-david@gibson.dropbear.id.au> <4E3B8ACA.7080104@web.de> <20110805153053.GA15083@amt.cnet> <20110808060328.GB20120@yookeroo.fritz.box> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: Marcelo Tosatti , Jan Kiszka , qemu-devel@nongnu.org, agraf@suse.de, kvm Return-path: Received: from mx1.redhat.com ([209.132.183.28]:24106 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751460Ab1HHIYQ (ORCPT ); Mon, 8 Aug 2011 04:24:16 -0400 In-Reply-To: <20110808060328.GB20120@yookeroo.fritz.box> Sender: kvm-owner@vger.kernel.org List-ID: On 08/08/2011 09:03 AM, David Gibson wrote: > Second, if userspace qemu passing hugepages to kvm can cause (host) > kernel memory corruption, that is clearly a host kernel bug. So am I > correct in thinking this is basically just a safety feature if qemu is > run on a buggy kernel. Seems so, yes. 2.6.2[456] are exploitable. We only found out after these were all released. > Presumably this bug was corrected at some > point? Is the presence of the SYNC_MMU feature just being used as a > proxy for "is this kernel recent enough to have the corruption bug > fixed"? SYNC_MMU actually fixes the bug. > In any case this test sure as hell needs a big comment next to it > explaining this context. Yes. > > > Why are mmu notifiers not implemented for PPC again? > > It's just not done yet; we're working on it. (That is, mmu notifiers > are certainly present on PPC, it's just they're not wired up to kvm, > yet). > If ppc doesn't have this issue even without SYNC_MMU, we can make the check x86 specific. -- error compiling committee.c: too many arguments to function