From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752131AbbIKIPf (ORCPT ); Fri, 11 Sep 2015 04:15:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47069 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751908AbbIKIPd (ORCPT ); Fri, 11 Sep 2015 04:15:33 -0400 Date: Fri, 11 Sep 2015 11:15:30 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: gleb@kernel.org, pbonzini@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, cornelia.huck@de.ibm.com Subject: Re: [PATCH V4 0/4] Fast MMIO eventfd fixes Message-ID: <20150911111453-mutt-send-email-mst@redhat.com> References: <1441941457-23630-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1441941457-23630-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 11, 2015 at 11:17:33AM +0800, Jason Wang wrote: > Hi: > > This series fixes two issues of fast mmio eventfd: > > 1) A single iodev instance were registerd on two buses: KVM_MMIO_BUS > and KVM_FAST_MMIO_BUS. This will cause double in > ioeventfd_destructor() > 2) A zero length iodev on KVM_MMIO_BUS will never be found but > kvm_io_bus_cmp(). This will lead e.g the eventfd will be trapped by > qemu instead of host. > > 1 is fixed by allocating two instances of iodev. 2 is fixed by ignore > the actual length if the length of iodev is zero in kvm_io_bus_cmp(). > > Please review. I think we should add a capability for fast mmio. This way, userspace can avoid crashing buggy kernels. > Changes from V3: > > - Don't do search on two buses when trying to do write on > KVM_MMIO_BUS. This fixes a small regression found by vmexit.flat. > - Since we don't do search on two buses, change kvm_io_bus_cmp() to > let it can find zero length iodevs. > - Fix the unnecessary lines in tracepoint patch. > > Changes from V2: > - Tweak styles and comment suggested by Cornelia. > > Changes from v1: > - change ioeventfd_bus_from_flags() to return KVM_FAST_MMIO_BUS when > needed to save lots of unnecessary changes. > > Jason Wang (4): > kvm: factor out core eventfd assign/deassign logic > kvm: fix double free for fast mmio eventfd > kvm: fix zero length mmio searching > kvm: add tracepoint for fast mmio > > arch/x86/kvm/trace.h | 18 ++++++++ > arch/x86/kvm/vmx.c | 1 + > arch/x86/kvm/x86.c | 1 + > virt/kvm/eventfd.c | 124 ++++++++++++++++++++++++++++++--------------------- > virt/kvm/kvm_main.c | 4 +- > 5 files changed, 96 insertions(+), 52 deletions(-) > > -- > 2.1.4