Subject: Re: [PATCH v7 3/3] drivers/vfio: EEH support for VFIO PCI device

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 29 May 2014 07:58:31 +1000

On Wed, 2014-05-28 at 22:49 +1000, Gavin Shan wrote:
> 
> I will remove those "address" related macros in next revision because it's
> user-level bussiness, not related to host kernel any more.
> 
> If the user is QEMU + guest, we need the address to identify the PE though PHB
> BUID could be used as same purpose to get PHB, which is one-to-one mapping with
> IOMMU group on sPAPR platform. However, once the PE address is built and returned
> to guest, guest will use the PE address as input parameter in subsequent RTAS
> calls.
> 
> If the user is some kind of application who just uses the ioctl() without supporting
> RTAS calls. We don't need care about PE address. 

I am a bit reluctant with that PE==PHB equation we seem to be introducing.

This isn't the case in HW. It's possible that this is how we handle VFIO *today*
in qemu but it doesn't have to be does it ?

It also paints us into a corner if we want to start implementing some kind of
emulated EEH for selected emulated devices and/or virtio.

Cheers,
Ben.