From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: [PATCH v3 9/9] kvmtool: virtio: enable arm/arm64 support for bi-endianness Date: Wed, 07 May 2014 11:39:17 +0100 Message-ID: <87ppjpootm.fsf@approximate.cambridge.arm.com> References: <1398363443-3764-1-git-send-email-marc.zyngier@arm.com> <1398363443-3764-10-git-send-email-marc.zyngier@arm.com> <20140506142807.GI30234@arm.com> <87mweuq0os.fsf@approximate.cambridge.arm.com> <87y4ydoqs2.fsf@approximate.cambridge.arm.com> <536A06C1.8010709@suse.de> Mime-Version: 1.0 Content-Type: text/plain Cc: Peter Maydell , Will Deacon , Pekka Enberg , "kvmarm\@lists.cs.columbia.edu" , "kvm\@vger.kernel.org" , Greg Kurz , Rusty Russell , Michael Tsirkin To: Alexander Graf Return-path: Received: from fw-tnat.austin.arm.com ([217.140.110.23]:40696 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932180AbaEGKj0 (ORCPT ); Wed, 7 May 2014 06:39:26 -0400 In-Reply-To: <536A06C1.8010709@suse.de> (Alexander Graf's message of "Wed, 7 May 2014 11:11:13 +0100") Sender: kvm-owner@vger.kernel.org List-ID: On Wed, May 07 2014 at 11:11:13 am BST, Alexander Graf wrote: > On 05/07/2014 11:57 AM, Marc Zyngier wrote: >> Huh? What if my guest has usespace using an idmap, with Stage-1 MMU for >> isolation only (much like an MPU)? R-class guests anyone? >> >> Agreed, this is not the general use case, but that doesn't seem to be >> completely unrealistic either. > > Yes, and once that user tries the same without idmap virtio ends up > overwriting random memory. And how different is that from the kernel suddenly deciding to use VAs instead of PAs? Just as broken. Are we going to prevent the kernel from using virtio? > It's just not a good idea and I'd much rather see us solve this > properly with virtio 1.0 really. Again, what is virtio 1.0 doing here? M. -- Jazz is not dead. It just smells funny.