From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753560AbcEWSXb (ORCPT ); Mon, 23 May 2016 14:23:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48309 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753476AbcEWSXa (ORCPT ); Mon, 23 May 2016 14:23:30 -0400 Subject: Re: powerpc/pseries: start rtasd before PCI probing To: Greg Kurz , Michael Ellerman References: <146399210850.26372.5857516772891352049.stgit@bahia.huguette.org> Cc: Michael Roth , linux-kernel@vger.kernel.org, qemu-ppc@nongnu.org, Paul Mackerras , linuxppc-dev@lists.ozlabs.org, David Gibson , kvm-ppc@vger.kernel.org From: Thomas Huth Message-ID: <57434A97.90501@redhat.com> Date: Mon, 23 May 2016 20:23:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <146399210850.26372.5857516772891352049.stgit@bahia.huguette.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 23 May 2016 18:23:24 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23.05.2016 10:28, Greg Kurz wrote: > A strange behaviour is observed when comparing PCI hotplug in QEMU, between > x86 and pseries. If you consider the following steps: > - start a VM > - add a PCI device via the QEMU monitor before the rtasd has started (for > example starting the VM in paused state, or hotplug during FW or boot > loader) > - resume the VM execution > > The x86 kernel detects the PCI device, but the pseries one does not. > > This happens because the rtasd kernel worker is currently started under > device_initcall, while PCI probing happens earlier under subsys_initcall. > > As a consequence, if we have a pending RTAS event at boot time, a message > is printed and the event is dropped. > > This patch moves all the initialization of rtasd to arch_initcall, which is > run before subsys_call: this way, logging_enabled is true when the RTAS > event pops up and it is not lost anymore. > > The proc fs bits stay at device_initcall because they cannot be run before > fs_initcall. > > Signed-off-by: Greg Kurz > --- > arch/powerpc/kernel/rtasd.c | 19 ++++++++++++++----- > 1 file changed, 14 insertions(+), 5 deletions(-) By the way, same is true for device UNplugging: When unplugging devices in QEMU while the firmware is still running, they are never properly removed from the guest. I've checked it, and your patch fixes this problem as well! Great :-) Tested-by: Thomas Huth