From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [Qemu-devel] [RFC PATCH] vfio: add fixup for broken PCI devices Date: Mon, 28 May 2012 16:15:24 +0300 Message-ID: <20120528131524.GA22623@redhat.com> References: <4FBF3627.3030504@ozlabs.ru> <20120528124410.GC21778@redhat.com> <4FC3740A.4060801@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Alexey Kardashevskiy , Alex Williamson , kvm@vger.kernel.org, qemu-devel@nongnu.org, Alex Graf , David Gibson To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:3872 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751667Ab2E1NPc (ORCPT ); Mon, 28 May 2012 09:15:32 -0400 Content-Disposition: inline In-Reply-To: <4FC3740A.4060801@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, May 28, 2012 at 02:48:10PM +0200, Jan Kiszka wrote: > On 2012-05-28 14:44, Michael S. Tsirkin wrote: > > On Fri, May 25, 2012 at 05:35:03PM +1000, Alexey Kardashevskiy wrote: > >> Some adapters (like NEC PCI USB controller) do not flush their config > >> on a sioftware reset and remember DMA config, etc. > >> > >> If we use such an adapter with QEMU, then crash QEMU (stop it with > >> ctrl-A ctrl-X), and try to use it in QEMU again, it may start working > >> immediately with previous config when pci_enable_device() is called > >> on that PCI function. > >> > >> To eliminate such effect, some quirk should be called. The proposed > >> pci_fixup_final does its job well for mentioned NEC PCI USB but not > >> sure if it is 100% correct. > >> > >> Signed-off-by: Alexey Kardashevskiy > > > > Won't current kvm device assignment be affected by this? > > Would be surprising if not. > > > If yes need to address that not just vfio. > > A reason to solve this at PCI level? > > Jan > Sure, and I think this is what Benjamin Herren was suggesting. I just wanted to add another reason. -- MST