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Re: [Xen-devel] [PATCH v5 9/9] xen/pciback: Implement PCI reset slot or bus with 'do_flr' SysFS attribute

On Fri, Dec 05, 2014 at 10:30:01AM +0000, David Vrabel wrote:
> On 04/12/14 15:39, Alex Williamson wrote:
> > 
> > I don't know what workaround you're talking about.  As devices are
> > released from the user, vfio-pci attempts to reset them.  If
> > pci_reset_function() returns success we mark the device clean, otherwise
> > it gets marked dirty.  Each time a device is released, if there are
> > dirty devices we test whether we can try a bus/slot reset to clean them.
> > In the case of assigning a GPU this typically means that the GPU or
> > audio function come through first, there's no reset mechanism so it gets
> > marked dirty, the next device comes through and we manage to try a bus
> > reset.  vfio-pci does not have any device specific resets, all
> > functionality is added to the PCI-core, thank-you-very-much.  I even
> > posted a generic PCI quirk patch recently that marks AMD VGA PM reset as
> > bad so that pci_reset_function() won't claim that worked.  All VGA
> > access quirks are done in QEMU, the kernel doesn't have any business in
> > remapping config space over MMIO regions or trapping other config space
> > backdoors.
> Thanks for the info Alex, I hadn't got around to actually looking and
> the vfio-pci code and was just going to what Sander said.
> We probably do need to have a more in depth look at now PCI devices and
> handled by both the toolstack and pciback but in the short term I would
> like a simple solution that does not extend the ABI.

Could you enumerate the 'simple solution' then please? I am having
a frustrating time figuring out what it is that you are proposing.

> David

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