Re: [RFC PATCH] vfio: add fixup for broken PCI devices

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Fri, 2012-05-25 at 17:35 +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.

I think we should create a new quirk category... call it pci_fixup_reset
or something like that, which is responsible for blasting the thing into
submission when ownership changes.

We'll need these for more than just USB I suspect.

Cheers,
Ben.

> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>  drivers/vfio/pci/vfio_pci.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 1e5315c..6e7c12d 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -88,6 +88,8 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
>  {
>  	int bar;
>  
> +	pci_fixup_device(pci_fixup_final, vdev->pdev);
> +
>  	pci_disable_device(vdev->pdev);
>  
>  	vfio_pci_set_irqs_ioctl(vdev, VFIO_IRQ_SET_DATA_NONE |