Re: [PATCH kvm-unit-tests v5 13/14] pci: add msi support for 32/64bit address

[Alexander Gordeev <agordeev@redhat.com>]

On Tue, Nov 22, 2016 at 12:59:20PM +0800, Peter Xu wrote:
> On Mon, Nov 21, 2016 at 08:27:52PM +0100, Alexander Gordeev wrote:
> 
> [...]
> 
> > > +void pci_cap_walk(struct pci_dev *dev)
> > > +{
> > > +	uint8_t cap_offset;
> > > +	uint8_t cap_id;
> > > +
> > > +	cap_offset = pci_config_readb(dev->bdf, PCI_CAPABILITY_LIST);
> > > +	while (cap_offset) {
> > > +		cap_id = pci_config_readb(dev->bdf, cap_offset);
> > > +		printf("PCI detected cap 0x%x\n", cap_id);
> > > +		if (cap_handlers[cap_id])
> > > +			cap_handlers[cap_id](dev, cap_offset);
> > > +		cap_offset = pci_config_readb(dev->bdf, cap_offset + 1);
> > > +	}
> > > +}
> > 
> > Are you sure the function above is safe without range (sanity) checks?
> 
> No. :) But if something goes wrong, I guess that's possibly a QEMU PCI
> bug. I can add some check if you think is necessary, like, make sure
> the loop goes no more than a specific value?

Yes - I suppose PCI cap. list has a limit.

> Thanks,
> 
> -- peterx