From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:47240) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QqL8B-00051C-UC for qemu-devel@nongnu.org; Mon, 08 Aug 2011 04:24:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QqL8A-0000wY-NV for qemu-devel@nongnu.org; Mon, 08 Aug 2011 04:24:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:8417) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QqL8A-0000wL-DM for qemu-devel@nongnu.org; Mon, 08 Aug 2011 04:24:14 -0400 Message-ID: <4E3F9D29.2000708@redhat.com> Date: Mon, 08 Aug 2011 11:24:09 +0300 From: Avi Kivity MIME-Version: 1.0 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> In-Reply-To: <20110808060328.GB20120@yookeroo.fritz.box> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] Permit -mem-path without sync mmu List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Marcelo Tosatti , Jan Kiszka , qemu-devel@nongnu.org, agraf@suse.de, kvm 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