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

From: David Vrabel
Date: Fri Dec 05 2014 - 05:30:18 EST

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.

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