Re: [PATCH v3 2/3] vfio/pci: Tolerate oversized BARs by disallowing mmap

[Christoph Hellwig]

On Tue, Jun 18, 2024 at 09:51:34AM -0600, Alex Williamson wrote:
> > -		if (!resource_size(res))
> > +		if (!resource_size(res) ||
> > +		    resource_size(res) > (IOREMAP_END + 1 - IOREMAP_START))
> >  			goto no_mmap;
> >  
> >  		if (resource_size(res) >= PAGE_SIZE) {
> > 
> 
> A powerpc build reports:
> 
> ERROR: modpost: "__kernel_io_end" [drivers/vfio/pci/vfio-pci-core.ko] undefined!
> 
> Looks like only __kernel_io_start is exported.  Thanks,

And exported code has no business looking at either one.

I think the right thing here is a core PCI quirk to fix the BAR
size of the ISM device instead of this hack in vfio.