From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laszlo Ersek Subject: Re: [PATCH 3/3] arm, arm64: KVM: handle potential incoherency of readonly memslots Date: Sat, 22 Nov 2014 11:26:42 +0100 Message-ID: <547064E2.4070904@redhat.com> References: <1416236333-9378-1-git-send-email-ard.biesheuvel@linaro.org> <1416236333-9378-3-git-send-email-ard.biesheuvel@linaro.org> <546A146E.1020804@redhat.com> <546A1905.6080607@redhat.com> <546D288F.1040107@samsung.com> <20141121111936.GA1785@cbox> <546FEBF3.6030401@samsung.com> <20141122101835.GJ3401@cbox> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Paolo Bonzini , Ard Biesheuvel , kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com, drjones@redhat.com, wei@redhat.com, kvm@vger.kernel.org To: Christoffer Dall , Mario Smarduch Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34539 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750761AbaKVK10 (ORCPT ); Sat, 22 Nov 2014 05:27:26 -0500 In-Reply-To: <20141122101835.GJ3401@cbox> Sender: kvm-owner@vger.kernel.org List-ID: On 11/22/14 11:18, Christoffer Dall wrote: > On Fri, Nov 21, 2014 at 05:50:43PM -0800, Mario Smarduch wrote: >> But virtio writes to guest memory directly and that appears to >> work just fine. I read that code sometime back, and will need to revisit. >> > In any case, that's a QEMU implementation issue and nothing the kernel > needs to be concerned with. (Let's call it "qemu implementation detail" -- there's no "issue". The reason virtio works is not by incident, it has a known cause. As confirmed by Peter, there's no problem with the virtio buffers because the guest doesn't mark them as uncacheable, so *all* accesses go through the dcache.) Thanks Laszlo