Re: [PATCH 0/2] vfio/type1/pci: IOMMU PFNMAP invalidation

[Alex Williamson]

On Fri, 15 May 2020 11:22:51 -0400
Peter Xu <peterx@xxxxxxxxxx> wrote:

> On Thu, May 14, 2020 at 04:55:17PM -0600, Alex Williamson wrote:
> > > I'm not if this makes sense, can't we arrange to directly trap the
> > > IOMMU failure and route it into qemu if that is what is desired?  
> > 
> > Can't guarantee it, some systems wire that directly into their
> > management processor so that they can "protect their users" regardless
> > of whether they want or need it.  Yay firmware first error handling,
> > *sigh*.  Thanks,  
> 
> Sorry to be slightly out of topic - Alex, does this mean the general approach
> of fault reporting from vfio to the userspace is not gonna work too?

AFAIK these platforms only generate a fatal fault on certain classes of
access which imply a potential for data loss, for example a DMA write to
an invalid PTE entry.  The actual IOMMU page faulting mechanism should
not be affected by this, or at least one would hope.  Thanks,

Alex