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Date: Mon, 28 May 2012 16:15:24 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20120528131524.GA22623@redhat.com>
References: <4FBF3627.3030504@ozlabs.ru> <20120528124410.GC21778@redhat.com>
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Subject: Re: [Qemu-devel] [RFC PATCH] vfio: add fixup for broken PCI devices
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To: Jan Kiszka <jan.kiszka@web.de>
Cc: kvm@vger.kernel.org, Alexey Kardashevskiy <aik@ozlabs.ru>, qemu-devel@nongnu.org, Alex Graf <agraf@suse.de>, Alex Williamson <alex.williamson@redhat.com>, David Gibson <david@gibson.dropbear.id.au>

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 <aik@ozlabs.ru>
> > 
> > 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