linux-kernel - Re: [Xen-devel] [PATCH v5 9/9] xen/pciback: Implement PCI reset slot or bus with 'do

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Message-ID: <20141208160402.GF7745@laptop.dumpdata.com>
Date:	Mon, 8 Dec 2014 11:04:02 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	David Vrabel <david.vrabel@...rix.com>
Cc:	Alex Williamson <alex.williamson@...hat.com>,
	Sander Eikelenboom <linux@...elenboom.it>, bhelgaas@...gle.com,
	linux-pci@...r.kernel.org,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org
Subject: Re: [Xen-devel] [PATCH v5 9/9] xen/pciback: Implement PCI reset slot
 or bus with 'do_flr' SysFS attribute

On Mon, Dec 08, 2014 at 10:38:09AM +0000, David Vrabel wrote:
> On 05/12/14 17:22, Konrad Rzeszutek Wilk wrote:
> > 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.
> 
> I've posted it repeatedly.

Are you referring to http://lists.xenproject.org/archives/html/xen-devel/2014-07/msg01270.html
which is still waiting for your feedback?

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